Why Inline 5 Engines Can't Be Carbureted and Why They're So Rare
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- Опубликовано: 23 сен 2023
- Here we have a inline five or straight five engine, now gasoline or petrol versions of this engine configuration are very uncommon despite offering some very interesting benefits. But what’s more interesting than their rarity is the fact that they were not made before 1976?
We made gasoline engines in pretty much every configuration imaginable many many years before 1976. Singles, all kinds of twins, Inline three, inline four, inline six, v4, v6, v8, v10, v12, everything was made and mass produced decades before the inline five. We even made oddball stuff like VR engines long before the inline five. In fact the inline five is the youngest gasoline engine configuration, it’s the last to enter mass production.
The question is why? Well the reason is that fuel injection technology didn’t mature before the mid-70s. What does fuel injection have to do with it? Well, the inline five doesn’t really work with carburetors. How come? We carbureted everything else very successfully. From singles to v12s. Is it because it has an odd number of cylinders?
Well we successful carbureted many different inline three engines so why not the inline five.
To understand it we have to visualize it.
So here we have our inline five engine. Let’s start by trying to make it work with a single carburetor. Logic dictates that we should place the carburetor in the middle. Now let’s connect the carburetor to the engine via an intake manifold. Do you see the problem?
It’s the very different length of the intake manifold runners. Because we have both a long engine and an odd number of cylinders we are forced to have a great difference in runner length which can lead to unequal performance of individual cylinders resulting in a rough running engine.
Ok let’s try to fix this by using two carburetors. That’s obviously a waste of time because we end up in a scenario where one carburetor feeds two and the other three cylinders, again we have unequal fueling between cylinders and a rough running engine. We could try distributing the two carbs on a single manifold so that each carb somehow feeds 2.5 cylinders? Well this is no different from a single carburetor setup because we can’t “tell the fuel” where it should go, because it’s all the same fuel in the same intake manifold, in this scenario the middle carburetor gets the most fuel, as both carburetors feed it nearly directly. As long as we have a single intake manifold for all the cylinders the number of carburetors doesn’t matter because we can’t tell the fuel from a particular carburetor to go into a particular cylinder.
How about this. We use one large and one small carb each with its own intake manifold. The larger one feeds three and smaller one two cylinders. If you know a bit about carburetors you probably know that getting this to run right would be extremely difficult and even if you could get it to run smoothly for the particular environment and altitude of the factory, tuning this setup in a different climate or as the engine ages would be nearly impossible because all the adjustments on one carburetor would not be proportional to the adjustments on the other and you would end up with a tuning nightmare and a scenario where two cylinders perform differently from the other three leading to a rough running engine.
So the only way out is to use five individual carburetors. In a way that inline four motorcycle engines use. Yes, this would work and would lead to a smooth running engine but the associated costs and tuning complexity simply make sense in a mass produced passenger vehicle.
Ok, but here’s a counter argument to everything I just said. There have been plenty of single carburetor single intake manifold inline six cylinder engines over the years, and some had very long and successful production runs. And if you look at their intake manifold you can observe a massive difference in length between the individual runners. As you can see the difference in length is pretty much the same in an inline six and an inline five, the only distinction is that in the inline six there’s two cylinders in the middle whereas is the inline five there’s only one.
So why does a single carb single manifold work for the six and not the five? The answer lies in the firing order.
A typical inline six has a firing order of : 1-5-3-6-2-4
Whereas a typical inline five has a firing order of: 1-2-4-5-3
As you can see in the inline six adjacent cylinders never fire one after but in the inline five they do. 1-2 followed by 4-5.
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If possible, please watch at least half the video before commenting about individual carbs, inline 6 single carb and carbed Audi i5. It's all in the video. After making the video I discovered, thanks to commenter "user-ox7lg4tp9s" that the carbed Audi i5 actually has a special intake synchronizing device or similar inside it that makes it work. I haven't yet dug much deeper but info is hard to find. I might try getting my hands on the physical manifold if possible and interesting.
Tottaly unrelated but can you stuck an vaccum to an exhaust to imprve scavenging? For small displacement, and totally real here 😢
YES, Audi 100 C3- 1.9 WH engine code, also Audi Coupe B2-1,9 WN engine codes, both carb, one is Keihin, one is zenith carb, that might make it easier finding the inlet manifold.
The "device" inside the manifold for a carbureted engine is probably just rational runner routing... but it would be interesting to see, and I'm certainly not buying an obscure old Audi and pulling the carb off to look. 🙂
Was just about to correct when i saw this message .being an owner of a audi 500se 2.3 10 valve carburated engine
😀 Thank You, Very Special, Quite Charming Middle Child!! 😃
2:38 This was the solution to straight eights in the 50s that had problems with cylinders 1 and 8 getting so little fuel they barely even fired on a single carb. They just put two carbs on a common manifold, one between cyls 2 and 3, one between 6 and 7. This solved the fuel distribution problems and the engines ran like clockwork.
50s? are you sure? most I8s disappeared before WW2
wow
@@igortchelzoff3736Buick straight 8 until 1953
@@igortchelzoff3736Maybe it was only the solution that arrived in the 1950s. The solution to a 30 year old problem 😅
They got twin carbs because that was the cheapest way to get a bit more power output to keep up with the competition. the reason why straight-8's were phased out in favour of V8's was not any problem with unequal cylinder charge. it was because a V8 is shorter - less issues with crank tortional resonance and wind-up, less weight, and less friction. And no need for a great long ugly bonnet. Pre-war a long bonnet was a marketing advantage as men perceived it as a statement of power, but post war, women buyers considered it ugly and unwieldy.
8 cylinders inline or 16 in V is the limit as far as crankshaft tortional resonance and windup is concerned - that's why you never see longer engines in large industrial engines - except that Caterpillar do make a V20 gas engine (the 3520) - but its power output is limited to the same as their diesel v16 in the same range, so that the long crank is not over-stressed.
I had a series of Audi 5 cylinders over the years, and they were all great. The major advantage in my opinion was that they had 6 main bearings, which made them pretty much indestructable. I ran all of my old Audis for several hundred thousand miles each without an engine failure. Of course you need to change the oil, and they would eat power steering pumps every 70K or so, but they were great cars.
I love the 5 cylinders. They are getting hard to find these days but you can do some epic turbo builds, and they sound so good
I don't know if it was because Audi 5 cylinders with Solex carbs were in my first two cars, but I have never driven anything that sounded as good. By modern standards they were a bit slow, my diesel Jeep has more than twice the power and over three times the torque, but if I could have my Audi 100 Avant GL5S today I would.
I loved the Audi 80, 5000 Turbos of the 1980’s but the turbos and water pumps would keep failing. They were all great to drive but not to own.
I know it's a v6 not a 5, but this also makes the dodge v6 magnums crazy strong. They are V8s with a shortened block. So they have 1 main bearing per cylinder. Whereas the v8 has the same 6 for 8 cylinders. Eventually I am going to build and boost the piss out of one to prove my theory.
I owned 2 '80s VWs with the Audi 5 cyclinder 1.9L, the first was carburettor, both did 200k miles with no major mechanical issues (first needed a new head gasket when I bought it at around 100k), both were great, reliable engines, just a couple of new water pumps. If I could still get hold of one I would be very tempted.
I used to have a 1990 Audi 80 Quattro with an inline 5. I got it really cheap because it wouldn't start when it got below 45 degrees F. If anyone has that issue check the fuse box, there were 4 fuses positioned in a manner that made it look like they were spares. The one missing was labeled timing. That car was a beast in the snow.
jesus christ i like the 80. but nearly none available with the 5cyl
@@clemenszink9909 It was my favorite car, until I hit a deer and immediately after a weird wind gust blew a portable basketball hoop onto the windshield. Like fate didn't want me to have her.
@@wesKEVQJ thats sad to hear. i really like the shape of the coupe!
As an owner of a Volvo 2.5 fivezylinder powered car i enjoy every trip on the Autobahn. The stock exhaust kills most of the sound but you can feel it. Gettig above 4000rpm gives me a smile. Audi RSs are more rude. The Volvo is kinda gentleman in this case..😂So sad that there will be no more fivers on the road in the future.
I had a Volvo S40 T5 2.5l 5 Zylinder Turbo. I still remember it very fondly... I loved that car.
Why would you have a stock exhaust, though?
uhhh, one of my dream is a Volvo C30 T5, it's just so unique
@@negativeindustrial Approved/legal exhausts are expensive in Germany...
@@MrNordsturm
Ah, got it. I always forget because as long as you have a converter it’s legal here in Texas. After 25yo nothing at all is required.
VW/Audi had two carburetted inline 5-cyl engines. The 1.9 was made 1980-82 while the 2.1 was made 1978-82. The former were available outside the US on VW Passat/Santana and Audi 80 variants while the latter was available, also outside the US, on the Audi 100 5S variants.
Yes, you are right. Here in my country the 5 cyl VW Passat and Santana and also some Audi 80 ran with a so sophisticated Pierburg carb.
Very well done, well organized, laid out and presented. A great overview of the drawbacks without getting bogged down in the minutiae. Bravo.
It was a lot of information I didn't even know I wanted.
As a mechanic since the 80's with various 5 cyl cars, I never thought that there was a reason why there was always injection on the 5 cyl.
Thanks for an interesting video.
The counter argument to the firing order issue is the same as the runner length issue found in all carburated engines, and was solved. With a mixture of runner pathing and runner diameter adjustment, you can terminate all the runners right under the carb such that the amount of fluid resistance is equal across all runners. This has been the stock design of v8 intakes.
Yes, but a v8 is not an inline 5. You have two opposed banks which changes things. As far as I know the intake manifold of the actual carbed inline 5 has something more complex to compensate and make the engine run acceptably, unfortunately it's impossible for me to find verifiable info on this and I never got one in my hands.
@@d4a but the two banks don't help, and actually make the problem worse because cylinders on opposite banks must be routed to the same carb barrel to work properly. Look at dual plane V8 intake manifolds(where are many illustrations online) to see how (with a normal cross-plane crank) the end cylinders from one bank are combined with the middle cylinders from the other bank to form a four-cylinder group which fires at even intervals. Runners pass over and under each other to achieve this.
To understand the dual-plane V8 manifolds for four-barrel carbs, it helps to realize that a 4-barrel is functionally two separate carbs in a shared housing, with each side being a progressive 2-barrel. That's one 2-barrel carb for each group of four cylinders... and those four cylinders are not all in the same bank.
The runner from any cylinder can arrive at the plenum with the same path length as the runner for every other cylinder, and in any position relative to the others that is desired.
@@brianb-p6586 Just adding that it's the vacuum signal of a 4 cylinder engine that the V8 carburetor is "seeing".
I'm guessing that on the 5 cylinder and "log" manifold the center cylinder would run rich.
Yes, @@peterdarr383 in the V8 4-bbl case the induction system works as two 4-cylinders.
The fix to carb issues with a "log" manifold on an inline-5 is to not use a "log" manifold... just as they are not used for properly designed 4's or 6's.
@@d4a mistake/missed the 3-carb/mechanically-injected options the outside use the jag-style-twin-casting-carb and the central/middle odd-child use a single-barrel as your 1st drawings had with a equaliser-pipe for all 5 cylinder's to balance air intake-manifolds ( exhaust manufacturing/manifold is probably okay with being casted-5L-cyl as 1-peace, but L6 in my experience/pro-mechanic 👨🔧🇺🇸 markets cracking in the middle and requires 2 or more parts/castings ) being casting as 1-peace not-3, not covered the mechanical-injection as there's lots of different ways to do it/design
on a mopar slant-6 1970 220CI~ or jeep-2006-LWB i still wouldn't use a central 4 barrel ( i own a 2g-charger + 1960-75 hemi-heavily-moded + EFI plus 7-speed-manual-transmission-ect for reference ) as it really wants ( IGT/6-carbs or ) 3-carbs ( and exhaust-L6 side 2X separately-casting 3cylindered murged the 3's-manifold down to one back/final-tailpipe vs my v8 hemi needing duels-tailpipes's but bank is 4-1 collator or 2 into 1 then down to 4-1/main-pipe ) or PFI/EFI the later of the 2 is my general preferences nowadays as im not into carbs anymore really but the video was something different/entertaining to me
It's easy to carburete that engine, just change the volume of the runners on the inner ones to reduce the engine side vacuum. Bernouli's formulas are thankfully easy to simulate, especially these days. It can also be tuned by using a shorter or longer tubing whip coming off of a nipple odd of the runner. There were plenty of 5cyl engines in the radial aircraft world and this was how they balanced them. Multiple cylinders pulling from one carb is no big deal as long as its consistent and repeating every 4 cycles.
Yea or put five carbs on it😂😂
I agree.
possibly ; exhaust pressure - dependant intake adjust
or just accept that runner length doesnt have to be the same. look at V8 dual plane intakes, or straight 6 intakes. their runners werent the same length. i figured this would be his reason when i clicked on the video, and sure enough, it was.
furthermore, the cross plane v8's also fire adjacent cylinders on the same bank, and have MORE overlap between intake strokes. they seem to do just fine.
Love this video, thanks! I wondered if at any point there was going to be suggestion than an equal-length intake manifold might cure the carb-fed inline 5 issues, but obviously it's pointless when fuel injection does it much better. We've got a Volvo inline 5 in a Ford S-Max and the first thing I noticed about it was how smooth it is and how it will pull cleanly almost from tickover, almost in any gear! Really underrated power delivery.
I used to drive a slant six engine and and thankful you brought it up. It was so funny to see such a large engine with a tiny simple little carburetor.
I’m a retired mechanical engineer and I really enjoy this channel immensely. Excellent content and fantastic explanation. Love it ❤
Yeah, this guy expains things so well without ueing jargon or advanced tech language.
@@partymanau Pity half of it is bs...like this vid, in which he himself admits that inline 5s CAN be carbed...lol, your standards must be pretty low
@@TheChzoronzonyou must be fun at parties
@@jkk916 I don't think you know when to apply that sentence properly... but ey, if that makes you feel smart, go ahead buddy ;)
@@TheChzoronzonAll I see from your end is criticism. Where are the videos where you explain how things work, and that is beyond reproach?
The carbureted Audi 5-cylinder actually had a long production life. After making its debut in the C2, the carb 5 continued to be available until 1988's C3 facelift. It was also used in the same 1.9 and 2.1-litre displacements in the B2 VW Passat, with the 2226 cc injected engine eventually also becoming available as that Passat's performance offering. The 1.9 in the Passat was pretty impressive in its day,.and gave up to 85 kW with the Pierburg twin-choke carb.
Exactly
Correct, I did my apprenticeship at VW, we had a Passat 5 cylinder with a carb as out test vehicle tolerance on, carb was a Pierburg 2B5
The carbed engine continued its life only in markets that had little or no emissions control legislation at the time, such as certain countries in Africa, some parts of South-Eastern Europe etc.
Yep, but that didn`t mean it couldn`t be carbed @@d4a
Yes. My dad had a 1980s B2 VW Passat with a carbureted 1.9 litre I5 in the UK. It was a good car.
Your explanation is phenomenally good. I was going to comment that a straight 6 has a similar intake runner problem to a 5, then you explained about the firing order. You are brilliant!
Wow. I was only going to watch part of this, but I had to finish. Fascinating! Great use of the graphics. Thank you.
Individual intake tubes of equal length should solve a lot of these issues.
Same concept as long used with exhaust header tubes.
Was thinking the same thing.
Could the fire order be changed in inline 5?
Yes, but I think the aim is always to reduce the length of the intake headers, to improve power at high rpm
@@davidrikelv9529 of course, but it will be even more shaky
I agree, I had a straight six with a carburetor. I don’t see a significant difference where the compression stroke occurs, either in 1,2 cylinders or 1,5. Nothing prevents us from solving the issue of filling in the same way as a manifold for a 6-line engine, with the only difference being that instead of the fifth we will connect the pipe to the second cylinder and so on.
A single carburetor for every cilinder works very well and no peak torque at all, you could fix that with changing the bore/stroke ration. My Yamaha XJ650J (4 cilinders) runs very well and from 2500-3000rpm (slightly above idle) pulls away nicely, could go to 9500 if I want to. Maximum torque is at 7200 but you have more than enough between 2500-7000 (I mostly stay below 6000) but the torque rises gradually between tose RPM,s no peak at all! Yes, the coniguration will be bulky, but that should be a bigger problem with motorcycles. I have to remove a lot to remove the carbs an fitting them in place afterwards is a hell of a job. But in the "carburetor" days most car engines were mounted longitudaly with a lot of space left and right of the engine, even the spare wheel was mostly mounted in the engine bay. Yes, 5 inline with carbs is probably not an economical or logical configuration (the history of ICE's is filled with uneconomical and/or unlogic configurations), but it could work. Definitely if you give it a YICS (after the carburetors intakes are linked to eachother before they go to the cilinders, improving emissions) like my '82 Yamaha which I run almost daily these days, if it had "peak torque" it would be a hell of a ride every day to my work (+/75km's a day). The Honda CBX had an inline 6 with 6 carbs.
I was going to say the same. My 1981 Kawa has one carb per cylinder. A bit of a pain but effectively it´s like 4 single cylinder engines connected at the crankshaft. Other than practicality, you could add a fifth cylinder. Honda had a six in line with six carbs. Imagine synching them…
I drive a Honda GL1500 Valkyrie. 6 carbs 6 cyl boxer. Except for gear 4 and 5, the power unfolds smooth. 5th has a clear spike at around 3k rpm (6,5k max).
A long runner between the carb and block will bring the torque back down from the stars a bit especially with a nice smoothe bend. Like a c shaped intake runner from the side of the block up over the top with side drafts over the valve cover. Surely your hood won't mind the extra ventilation!😂
I really enjoy your videos. You always cover interesting topics and have a very natural, engaging style of delivery. Your animations are also effective and concise. Thank you for the entertaining and informative content.
Always wanted to learn about engines and you are a one stop shop of quality education. Thanks!
I had a VW Passat (B2) with the 1.9 L I5 from 1981 in Germany. That engine had a carburetor and 115 PS. It was a blast running on the Autobahn and listening to the sound of the engine. The car was pretty fast for the time (and you were still able to drive fast). BTW, the 5 cylinder Diesel engine from Mercedes is also a child of Ferdinand Piéch. He worked for Mercedes as a consultant after his time at Porsche and before going to Audi.
exactly, the guy is putting out misinformation on technical information as well as the history.
@@thegenrlI think he's making valid points. It's not that the issues could not be solved, just that the solutions are too expensive for mass production.
@@getwellgetfitgetlaid3514 solved by making runners equal length. Lots of inline sixes have similar challenge.
The reason why 5s were very rare wasn’t carburetion - it was roughness. And lack of need. The advent of transverse fwd larger cars couldn’t fit an I-6.
@gordtulk Which in turn reqires more space and more expensive intake manifold. One of the main benefits of V-engine over inline is the short intake manifold.
Everybody says the inline 5 sounds great until the inline 7 walks in the room
Followed by the inline 9
@@d4a weak, we make a W9 for that
Followed by the straight 8!@@d4a
Your videos are fantastic! Have learned so much watching them. Thanks👍
You are so appreciated! Thanks for everything u do.
Rover built a inline 5 in 1963, it had 3 carburettors, 2 big and 1 small. The project was scrapped due to the purchase of the Buick 215
decent chunk of useless knowledge :D
I’ve worked on many 5 cylinder carbureted marine engines. They had 3 carbs.
Hello
It was gasoline or diesel engine ?
Two stroke gasoline. Force 150 outboard.
I had an Audi 100 5s. That was a carburated inline 5. It was a great running engine.
Awesome D4A content as per usual! I got a 3.5 Colorado I5 I’m modifying, such cool motors and cool sounding 😎
Thank you for your support, I highly appreciate it.
How is this not top comment
Slight correction, Audi mounted the I5 longitudinally, not transversally, but space was the reason - Audi has whole engine in front of the front axle due to concept of their 4wd system.
Small correction,audi did that not because of four wheel drive ...but because it traditionally had that arengment of engine and transmission for front wheel drive ..
@@vasopel true that, 4wd came after the I5.
@@Papinak2 ;-)
…and awful handling.
@@808bigisland - If you don't know how to drive.
I owned a 115 hp 5 cylinder VW Passat with a two barrel carburator. Great engine.
My dad had a 1985 Passat 5 cylinder. I think it was a Pierburg twin barrel carb that it used.
During WWII there were predictions that Chevy was working on an inline five.
It seems to me that the cross section of the runners on a cast manifold could vary enough to even out the flow, although getting the velocity to be equal throughout the RPM range could be tricky.
In any case, a snake farm of welded tubing would absolutely work.
Great video, thank you for taking the time to post it
The I5’s used by Audi in the 2.5 (both iron and aluminum blocks, and same for the NA 07K engines) don’t have balance shafts. You should do a video on how they get it to run so smooth and well without balance shafts.
Sometimes I forget the car is running 🤣
@@CarelessGamer15 I have stiffer drive train mounts in my TT RS for performance benefits, which transmits the vibrations from the engine a bit more than stock. Ironically, I notice the engine most when sitting still idling. Once driving, especially over 3k RPM, it’s very smooth.
The main crank is weighted and balanced, Volvos don't have balance shafts either. Go to Speedkar99 he has great videos of both Audi/VW and Volvo i5 engine teardowns.
@@JustinBoneGotta love that poly bushing life. "I'm not revving because I want to race you, I'm just trying to make my change stop buzzing in the cup holder."
I am pretty sure the Volvo white block I5 engines do not have balance shaft(s) either.
Just for clarification, first 5 cyl. diesel was mounted first time in W115, not W123 as seen at the end of your movie. It was OM617 engine, first version was signature OM617910, 3005ccm displacement and 79hp of power. W123 was produced from November 1975. Writing that because it may be a little misleading ;). I had that one in my W115, it was my first car.
It was fuel injected.
@@jamesgeorge4874 Yes, it was diesel.
Lancia built an inline 5 diesel in 1938, for a military truck.
The Mercedes engines are legendary, though.
240D 3.0❤my first car too
@@petrhencl8822240 should have been a 2.4l 4 cylinder.
That's interesting. Never thought of it that way. Ill have to look up the inline 5 diesel. Great stuff as always
Excellent video. If anyone is interested, the reason why the i5 can't just change the firing order to overcome the fueling issue is to do with balancing. You're spot on about the 5 cylinder diesel - VW's version was astonishingly smooth, piles of torque and a pleasure to drive.
Fantastic video. The best internal combustion channel on the internet imo.
Few things to add. Audi made a lot of i5 engines with carbs on c2 and c3 platforms in europe. And the power is 85kw on some models. The same as kjets.
Other thing - one fot the most popular vag engine produced i think for more than 30yrs is i5 diesel. From audi c3/c4 and mostly vw t4-t5 use the same diesel i5 base. So it has its own big market
Interesting video and very well explained 😃👍👍
Thank you for this very informative video, I now realise why my Landrover TD5 engine had such a special soundtrack, I always knew it did but was never sure why.
Have driven 5 cylinder Audis a few times, I really like these engines for their sound, smoothness and relatively good fuel economy (better than most V6 engines anyway). Always been a bit surprised they are not more common as the counter argument to 4 & 6 Cylinders doing the job sufficiently is that you could replace both 4 & 6 cylinder engines with a 5 cylinder (maybe with performance turbo option) for some car models.
Yeah, it’s a shame we’re now stuck with boring I4s and V6s with very very few 5cyl left.
It's a Renault engine,early versions had the Renault name cast on firewall of the Mitsubishi FWD platform....which Volvo engineers/ marketing folks, consumers would claim it was Swedish engineered....a complete lie. Engine wave pattern exhaust is annoying,even the Honda 5 pot makes the same annoying exhaust notes.
Or you could say that it is an unnecessary intermediate step without the advantages of either side. Fuel economy OR power. It is an inherently unbalanced system. 6 inline are naturally perfectly balanced. 4 inline or V6 can be perfectly balanced with easy compensation. 5 bangers can not. They need two sets of mass compensators for the same smoothness.
You can make enough power for any daily driver car with a 4 cylinder engine. If you want more and you can't squeeze it out a 4 banger: Go a significant step and 6 are your friends! When using I6 you even can recover some added complexity by not needing any mass compensators at all.
Amazing, i didn't know that firing order played such a huge part in why some engines can or can't by carburated. I adore the Inline 5 a lot. i got introduced to it by the Audi Quattro(especially the Group B varient]. i love the v10 like sound. a true automotive symphony
They can be carbureted check out Alan milliard hand makes modified motorcycles he has built at least two Kawasaki motorcycles that has turned from triples into five cylinders and both are carbureted
@@malcolmwhite6588 he uses one carb/cylinder, right? And that solves the issue.
@@malcolmwhite6588one has to speak in generalities in the tagline to get views, sure it’s possible, he even says that Audi made one, but it just runs poorly.
On the automotive side you really should look into the Ram Chargers of the 60's. They were Engineers from Chrysler who raced on weekends and brought that tech to the Masses. They did some interesting stuff with intake pulses and plenums and runners. It's how Chrysler ended up with the Cross Ram on the 413/426 Wedge engines back in the mid 60's.
Necessity is the mother of invention. And as you mention, the I4 and I6 were able to cover all the needs with existing known methods. If there had been some regulation reason - like and added tax per cylinder - I could see somebody tackling the I5 issues before fuel injection. An equal length intake runner design where the posts at the carb are swapped so no consecutive firing cylinders have a neighboring port at the carb could resolve those issues. But long intake runners tend to hurt throttle response and add low end at the cost of high rpm breathing.
I've got a v10 audi, it kinda sounds like two inline 5:s together. Love it
The 5 cylinder VW Jetta has a beautiful exhaust note when she's running down the highway. The cold air intake system just compliments the music.
Stock 07k engines roar..... on a cold day not bothered by heat soak, the intake sound wakes up the neighbors.
Audi made a 5E and a carbureted 5S
Great explanation. While fuel distribution in the manifold my be a contender, it's that firing order having more effect than manifold runner length in the case of a I5. Radial 5 cyl aircraft engines worked well with a single carb, placed at the bottom of the engine between #3 & #4 The carburetor typically place low, between the #3 & #4 cylinders resulted in unequal fuel mixture paths. With a 1-3-5-2-4 firing order, every other cylinder fired in the sequence. Just from personal observation, Packard, Buick, and Pontiac had I8 engines until 1954. And maybe some others that I don't know of. Thanks.drivingforanswers, your content always hits a bullseye every time.
Superb content as always
Also the VW Passat b2 1.9 5 cylinder. It had a carburetor. We had one. 1982
Fantastic video🎉
Small correction: As far as I know, Audi didn't mean to use the 5 in transversal lay out initially. They just couldn't use an inline 6 in its cars longitudinally, so they went to the 5.
Ferdinand Piech is the father of this beauties.
I was wondering about that as I seem to remember all those late 70s and early 80s Audi Quattro, Audi Coupe and Audi 100 were longitudinal. The first transverse Audi 5 cylinder car, must have been a couple of decades later.
but today, I suspect they do everything thinking in the possibility of sharing it with VW cars and such. So I think they think how to fit it in both longidinal and transvesal ones.
Thinking about it, all Audi's were longitudinal engines, and they made their fame with the 5 cyl in performance aplications. I think the modern tranversal configuration was just for nostalgia of the 5's era, and not techinical terms. The TSI's 4cyl would pretty much do this job in the RS's.
@@alexjenner1108 My first car was a 198x Audi 80 Quattro 5cyl. I loved that car.
@@alexjenner1108and Audi 200
I had one in my GMC Canyon, Chevy also had one in the Colorado. I never had any problems with it. A radial engine is sort of like an inline engine with all cylinders on the same place on the crankshaft. That arrangement has equal spaed intakes. They were usually in 5, 7, and 9 cylinder rows..
4 stroke radial engines can only be an odd number of cylinders. Each time a cylinder fires, the next cylinder is on the exhaust stroke. So in 2 revolutions, each cylinder gets to fire. A 2 stroke wouldn't have that problem, and there is at least one example of of a 2 stroke radial with 2 banks of 4 cylinders.
Interesting video. Thanks, and happy Christmas!
Excellent presentation. My first Audi was a GT5S with a carbureted 2 litre engine. I did have problems with the carb but they weren’t related to the issues discussed here. I think balancing shafts went a long way to compensating for the roughness. The I5 is a fantastic engine. I had many other fuel injected 5 cylinder Audis since. Beautiful noise!
Diesel I5s were pretty reliable too.
Very tough engine too. Well maintained they lasted forever. And were tuned to outrageous power levels in the S1 versions of the Quattro. I still drive Audis but I so miss my Ur Quattros.
@@alwoolhouse6255those 70s/80s Audis were fantastically over-engineered mechanically. There is a video on RUclips of a chap who uprated his B2 80 Quattro from its standard 136hp to over 600bhp using the standard running gear.
Audi introduced the Inline 5 with carburator in Europe in 1978 in the Audi 100 B2 (Type 43). It was the offered as the highest engine option for the Volkswagen Passat B2 (Type 32B) from 1980 till 1983 before it was succeded by the version with fuel injection with the same power output (in 1982 for the Audi with ID "WB", in 1983 for the Passat with "WN") but with different displacement (1921ccm to 2144ccm in the Audi). So the I5 with carburator was pushing the same power output as the later fuel injection versions (85kW/115HP) and the reason for having it was simply cost. The mechanical fuel pump though was directly placed above the spark plugs between cyl 4 and 5 and in case of any leakages... the enigine was notorios for engine burns.
The Audi fuel injected versions in the US had similar power output to the carb versions due to emission regulations, but in Europe the fuel injected versions were 130/136hp.
My first car was an 1977 Audi 100 5E (2144 ccm, 5 cyl, 10 valve, Bosch K-Jetronic fuel injection)136 hp. My brother had at the same time an 1978 Audi 100 5S, same engine but with a Zenith carburetor and 115 hp. The carbureted one had the best sound! Great engines except for the use of the water pump as the timing belt tensioner = bad idea.
Always a pleasure to listen to your superb videos sir. ❤❤❤❤
It'd be a more complicated to make, but you could cross over the intake runners for cylinders 2 and 4, then at the carburettor, the 1-2-4-5-3 order becomes 1-4-2-5-3. The runner for the middle cylinder is still a lot shorter than the others, but it wouldn't be much worse than some of the straight-six intakes shown.
Would not work. The crankshaft would be unstable
1-3-5-2-4?
@@NikolaTesla-nb5nm he specified that change *the intake runners* (snake them around the third) but do not change the firing order.
It's a shame the I5 never really made it mainstream in more cars/trucks, it's such a cool sounding engine. That moment when you think you hear a Viper but it's a Chevy colorado, lol
So it's not just me who thought it sounded like a V-10 lol
Had my 20v Fiat Coupe Turbo for 20yrs...the engine's power delivery and the sound is intoxicating.
The Mercedes OM617 is one of my favorite diesel engines and a childhood favorite at that! Well done.
The VW 2.5 TDI is one of the most reliable engines out there. And it sounds good :P
Well, here's the unasked question then... why wouldn't you be able to redesign the firing order of the i5? I'm sure something like 1-3-5-2-4 would fix the breathing issue on the carb at the expense of engine vibration, but if you have a balancing shaft anyway?
As someone who had never worked or seen an i5 engine in real life, I always thought the firing order would be 1 4 2 5 3, thinking that would keep the best of balance and keeping fires away from adjacent cylindres. My logic is, 4 is almost on the opposite side of 1, but that couple would be countered by 2 and 5, then 3 is in the middle of the engine so it wouldn't do that much of a rocking effect.
Maybe I'm not an engineer for a good reason. xD
@@rata536 Exactly! It's like when tightening lug nuts; you skip every other lug until they're all snug.
great vid and explanation.
Interesting.
I would like to see a similar video on V4 engines or the lack of them.
If it runs with fuel injection, it can run with a carburetor. Since a carb is a draw-through device, as long as there is negative pressure in the intake (intake stroke) it will pull fuel through with the air. It may not be optimal, but it WILL work.
The old heads who actually use science to do carb stuff put stuff like deflectors inside the intake manifolds to get equal flow and distribution. Kind of cringing at some points in this video.
I agree! But that's not quite how carburettors work. It's the air *flow* that causes fuel to be drawn in, not directly pressure or suction.
I seriously doubt that the proliferation of fuel injection had anything to do with the production of straight 5s. Probably nobody thought there was a good reason to build one. Nobody builds a straight 7 either.
I would have thought adding some baffles to the intake so the 3rd cylinder didn’t have such a direct shot from the carb would have solved the fuel balance issue.
45 years ago, I drove cab in an upscale city. The fleet had lots of big Cadillacs and Lincolns, and one lowly Mercedes, 5 cylinder diesel. I loved it and it was speed daemon. Pulling on to freeway, if you weren't careful, in seconds you were 20-30% over the limit, it was so smooth and powerful. Fine car and a great engine.
Diesels are fuel injected and very torquey
Thank you SO MUCH for these videos, you really break the subject down into an easy to understand sections. Even my pea sized brain can understand the subject thanks to you!
Fuel injected I5 would also benefit from equalizing the effective intake lengths.
As always, great video. I love the 3D CAD rendering, along with your very effective use of language. Your explanations are excellent! I wish the world had more people like you.
It wouldn't matter because you have 5 indivudual injectors and each one is located at an individual cylinder. There has never been a throttle body injected i5. Only sequential injection.
They actually can be run off a carbie, I know because I used to have a 5 cylinder carbie running off nos. Just need an intake that has equal length and a perfect centered split point in the intake piping to each intake port. All it takes is a mig welder.
The irony is that along with EFI, we now have the ability to make a computer designed carb manifold for anything with near-perfect mixing and flow.
And an EFI manifold that works properly.
We can also make the most powerful, most efficient steam locomotives to grace the rails, but our technology has 'unfortunately' superseded such needs.
@@jonathanrees3765 fuel doesn't travel through the manifold. Fuel is injected at the intake port of the head, not the intake opening of the manifold.
Exactly, so fuel injection CANNOT correct for bad airflow. Carbs (and throttle body injection) mix fuel air at intake so "correct" mixture (which DOES flow through manifold) will get to each cylinder - just at different volumes. Manifold with these problems using port or direct injection WILL give incorrect AFR to cylinders not getting enough, or to much air. So whole argument of this video is BS.@@threynolds2
@@threynolds2 Not necessarily right, and in fact, mostly wrong. Excluding Direct Injection cases, the majority of multi-port fuel injection has the injectors positioned at the intake manifold, not the engine head.
i like that you stepped back and looked at it from multiple perspectives and angles
Kubota M4700 tractors had an inline 5 diesel for many years. I believe it was the F2803. I always liked the sound of them too.
This was actually pretty informative! I didn't even realize that gasoline inline 5's were never mass-manufactured before 1976. Also, that SOUND is exactly the reason why I want an older Volvo wagon with a 2.5L B5 engine swap. 🥰
I like the graph where the I5 fits. It’s a small niche and explains why it’s wasn’t mass produced.
the rs3 is such a cool car, audi's rs division has evolved so much in the last decade
Very informative, nicely narrated. 💯
A simple solution that was used was intake designed so all runners to each cylinder were the same LENGTH, they kind of looked liked a tangled garden hose.
My dream engine/chassis combo would be an naturally aspirated, 2.5 liter, inline 5 with around 220 HP in an MX-5 or S2000 chassis.
That exact thing is the blue vehicle towards the end of the vid. Has ITBs too.
@@d4a I thought it was a Fiat coupe
@@d4a so why can't the engine be designed to fire 1-3-5-2-4 so that no adjacent cylinders are firing one right after the other on a carburetorated inline 5 engine .
@@craigalston2208 MAYBE it would make power distribution too much asymmetric along the revolution. MAYBE the weight distribution of pistons would be a problem.
But I also want a better answer.
Yet another fantastic video 👍😎
I was the glad owner of an Mercedes 250 from 1985, with an 5 cylinder D engine. A piece of art. Have been driving this car up to 686000 km from 150000 km that it had on the dashboard, when I bought it as used. Not a single problem with that car in this time. The engine was running exactly like the day I bought it.
Amazing car!
Have you seen the iconic direct sales letter Mercedes used to sell it?
Well worth the time to look that up, it is used ias an example in product marketing education.
You must have really kept up on the maintenance. Timing chain replacement, injectors serviced, etc.
This is so interesting to watch...big thnx
I loved my vw rabbit with the 2.5 liter straight 5. 2 door 5 speed manual.
Audi had multiple inline 5s with single carburetor, not sure how they dealt with the problem, but I am sure the engines worked fine. Check WN, WH engines with Keihin carb.
Exactly.. Audi 80/100 and CoupeGT 5S!
Aaah... to watch the video before commenting
@d4a individual carburetor? For the 5 banger?
As the former owner of a 1992 Force 150 outboard motor with a carbureted 5 cylinder engine, I can attest that its three separate carburetors had some crazy linkages to drive them all. Never had an issue with the carb tuning though.
Probably because it's a 2 stroke , the cylinders are usually feed via the crankcase and ports in the cylinder wall
Great video as always. I have a question: why do engines have the firing order that they do? Is it a hold over from the carbureted days? Is it the most efficient? Heat reasons? Do you already have a video on this subject and I missed it? Thanks to you or anybody else kind enough to elaborate 🤓
Great question. I'm not an expert in this, but I believe it has to do with applying torque to different parts of the crankshaft fairly evenly.
Additionally, the piston motion needs to be arranged in such a way as to minimize vibration - this video touches on that (primary/secondary balance).
Adhering to this balancing regimen informs when pistons are gonna be at TDC and thus even available for firing (if on the power stroke)
my folks had an 1976 Audi 100 LS with the 5 cylinder. To the ears of this 8 year old, nothing sounded sweeter than that engine. And it was a 5 speed, to maximize the fun sounds.
Wow such a great video again! Im honestly astonished at the sheer amount of videos that explain concepts about engines that no one has talked about! Thank you for always producing such original content! I hope you know that it is not going unseen, great work and story telling
For a while Rover was trying to develop 5- and 6-cylinder versions of the 4-cylinder engine in the P6. The 5 had one carburetor feeding 2 cylinders and one feeding 3.
Rover managing director William Martin-Hurst stumbled onto the Buick 3.5-liter aluminum V8. It was only slightly heavier than the existing 4 but much more powerful, so the proposed 5 and 6 were abandoned. It’s not clear that the issues you discuss couldn’t have been dealt with.
Having said that, fuel injection is a good thing regardless of the number of cylinders.
I was just about to write a similar comment so good minds think alike... Although Rover did initially have fueling issues it was generally considered that this would be overcome as progress was being made, until the V8 was found. Well before 1975 date as per this video!
Thanks for this ive always wondered why
The 2.4 20v jtd engine is a true gem. It's easily modified over 400bhp on stock engine parts. Sounds very nice as well
ok 400hp is too much, but to 275 hp it's only remap
According to a wonderful Jason Cammisa video highlighting inline-5’s, the reason for their melodic exhaust notes is that they produce a “perfect fifth”, which is the basis for a musical chord. I agree that inline-5’s and V-10’s have the sweetest sounding exhausts ever…even though I also adore the offset rumble of a V-8!
Minor nit to pick: Volkswagen also made a few I5s over the years, including the EA855 (in use until 2014 in the US market).
You mentioned the OM617 by everything but name there at the end, I see. One of the most well-regarded engines of all time.
617 is fuel injected, doesn't quite fit with his premise about carbs.
Inline five is an orphan for regular folks. Inline six is naturally balanced, quieter and the longer crankshaft gives more torque for the cubes. Even most semi tractors use them.
It would interest me how many manufacturers made inline 5 diesel engines.
You gave us the information for the gasoline inline 5, it would be nice if you also told us about who builds the diesel ones.
On a Sidenote: i enjoyed the inline 5 diesel in my w124 t model with every cell of my Body.
Thank you. Having owned a few of the MB Diesel 5 cylinders, I actually did wonder why it was not more common!
What did you Make The animations in?
Fusion 360 + paint net + premiere pro
@2:56 Honda did something kind of similar with the RA272 V12 in the 1960's. Before modern variable length intake runners, variable cam timing and variable valve lift they tuned the V12 engine as three separate four-cylinder "units" running different length intake stacks, cam profiles and timing on each of the different "units" on the same engine in a attempt to widen the power of the 1.5 liter V12 engine.
Dont forget about the VW I5 Jetta engine. It was a really good engine in its days. Equipped with VVL, VVT and variable intake length, it was extremely efficient, reportedly having a fuel consumption of about 5l/100km, even though its a 2.5l engine with over 100kWs.
Mine isn't too terribly efficient tbh. I get about 30mpg on the highway, not bad but not great.
I love my charming middle child. It's a volvo C30 T5. I had an Audi 100 ten valve 16 years ago and it was one of the most finiky engines I have ever owned.
Of course you can use a carb?! Audi 100C2 had a 5cyl with a Zenith 2B3 carb.
Watch the video
I owned a vw santana gl5 it had a single pierburg twin choke carburettor it ran nice
We owned a 2.5L I5 half-a-lambo-Gallardo engine powered VW Jetta for several years, which was pretty reliable, save for the crappy swashplate AC compressor I replaced. I always thought it sounded better than a V6 when you got on it hard, and while weird, it beat the 4 cylinder option. I always figured the reason we didn't see more was the lack of need, given existing I4, V6, and I6 engines. I had no idea it originated from the overlapped power stroke and sequential firing order. Cool and interesting watch my dude, as always.