Compression Myths - How much compression can you run on pump gas? Questions Answered
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- Опубликовано: 6 окт 2024
- This is a follow up video to, to selecting the right camshaft to match your compression.
Can you run your SBC 350 on 11:1 pump gas? Should you run it on pump gas? I take a deeper dive into the subject and discuss methods how you may be able to do so if you follow some precautions. Who killed the muscle car era? Maybe it’s not who we think.
Well explained.
I have a 66 pontiac starchief executive à little resto-mod old school myself with a factory 10:5 compression 389ci 389ci 4bbl 325hp and 425fp/Torque with 2.73 gear. I can run regular 87 gas but i can't have the same timing. I can ear the pinging as soon as i push the Torque at 2500 rpm. Before i understood fully how to be to be able to advance the timing, to be more snappy throttle the way i wanted the 4400 pounds car to be, i had to put supreme gasoline and a little shot of Lucas gasoline additive. Its the only way i like it to be snappy and roaring at pedal to the metal way. Pinging from pre-ignition is bad for the piston top i was told and my 389ci likes it like that. Maybe not yours but if you want to run higher compression engines, be sure your aware of what to do and not to do when it come to engine gasoline cocktails. You could ruin an engine in no time if you don't know the basics. Heat, octane, gas additive, ring gaps, blowby, cylinder compression, and fuel ratio " too rich or too lean".
Nice content. Well explained!
Sounds like you know how to manage it. I would use the best pump gas you can get! AG
Bring in a discussion on knock sensors and water injection and other ways to deal with detonation And the effect of fuel additives
Thanks for the suggestion. We will try to address it in future videos. AG
I was surprised to learn that when chemists formulated the leaded gasoline chemistry, they factored in deaths it would cause as one variable. Maybe the public didn’t know, but the people responsible did.
Where are you getting this information from?
Trolls be trollin'
Google it, I’ve posted a couple of sites but the responses got deleted.
@@ehb403
Screenshots are less likely to be deleted.
There has been much, much evil, wicked stuff going on for decades and they/them are blazingly ramping their evil deeds.
And now they/them are flat out telling you what their doing and get away with it because people have been mentally conditioned to believe the crap.
People have been conditioned to disbelieve the truth and real facts.
@@ehb403sounds like I have to wear my tin foil hat when looking for that...
I made 620hp on a 388 with 11.2 to one on 93 octane on dyno with amsoil fuel additive and so far in the car no problems 🙌
Thanks krista, that is a lot of power, can you tell us more about what went into the build?
My 399ci. with 10.7 to1 with 17* heads makes 641@6400 on 89 pump.
@@heshtesh Did it croak already?? Why risk it with 89 octane?? lol..
Thank you for your time and knowledge.
A lot about what the problems are, but not a lot of how to get around them.
Like changing carburetor boosters to change atomization. Cold versus hot inlet manifolds. Ignition curves. Combustion chambers, quench, headers, etc.
Again, thank you for sharing.
Happy building.
Thanks Julian. Your comments are giving me ideas for future video content. I will get to it eventually. AG
And to think aviation is still using lead.
I had exactly same scenario, engine and compression..
Easy fix, just lowered cylinder pressure by picking cam with late intake closing time..
Ended up with 165psi, was able to put a good amount ignition timing in it. Ran on 92 in the dunes for many years perfectly.
Thanks for sharing your experience Terry! 165 is a very safe pressure. AG
You should discuss quench/squish in relation to how high a CR can be run on 91/93 octane pump gas. It plays a big factor in avoiding lean pockets of mixture in the cylinder.
BTW: I never understood running 87 octane piss in an expensive, high compression engine.
Thanks Joseph. I did intend to do that in the last video. I guess I should make a script. Anyway, I will fit that in a future video. Thanks for the input/AG
I agree on the quench topic.
I thought we were going to be talking about Cam shaft's here. A good cam tuner can reduce you compression. I was told my 427 LS having 12 to 1 compression is a good place to be for 93 octane on the street with a good cam and quench number like .040. I'm in florida and my car runs fine except for the hottest days in the summer with the air on. I can tune it down to 22* timing in the summer and it's fine. There is always different blends of alcohol too, haven't tried that yet.
Thanks for your comments. AG
That is a gorgeous 427. I love the orange and black paint
Thanks for the nice compliment Hugh. AG
I’ve always been under the opinion that the air pump’s purpose was to also help with any unburnt hydrocarbons in the exhaust. Not sure if they were onto intake/exhaust reversion yet. 🤷♂️
Thanks Lujin, you are probably right about that. Thanks for your input. AG
I think most people confuse high compression with piston to deck height. Increased compression isn’t nearly as important as having your piston to deck height as close to 0 as possible. This in itself helps with detonation tremendously. Not to mention, every point in static compression increase is about a 3% increase in horsepower. That’s all well and dandy but 11.0:1 compression, you should be running e85 on the street anyway, not 87 pump gas. In my case, my static is 9.0:1, my piston to deck height is 0.015, my dynamic lowers overall compression down to 8:5, and the turbo brings it back up to 20:1 depending on boost pressure. So yeah, out of boost with wastegate locked open I can run 87 octane. With boost, it’s either e85 or 93 with alky. You’d have to be a fool to run 87 octane in any engine, and if it’s all you have in your area, at least add some VP octane booster.
Thanks Street. Lots of good technical information. i appreciate your input. AG
Love it! Great video. Looking forward to the 400 projects.
Thanks 100, glad you enjoyed it. Please keep watching! AG
Nice explanation of the area of the piston and the psi pushing on the piston. I ran across an old Buick ad from the late 50's and their Nailhead V8 - they called it the B-12000 - it had 12000 pounds pushing on every stroke.
The end of high compression V8's from Detroit - I don't know, but it seems like all 3 of the big automakers were doing pretty good financially around 1970, but none of them invested in better cylinder head and camshaft tech that would have helped keep HP decent even with the lower compression. Instead we got 190 HP 455's and 460's. A 190 HP Cadillac 500 engine. Even if they stopped using these big engines in mid size cars, their huge cars they made at the time would have benefitted from some investment.
Thanks John, that is interesting about the Buick ad. OEM's are driven by ROI, return on investment. They just want to make money! Good comments.
Emissions regulations killed hp as well.
Car manufacturers definitely gave in to pressures from big insurance and EPA. What's really interesting is if you look at hp numbers throughout the 70's, 80's & 90's they were dismal in comparison to hp #'s from the 60s. Then something really great happened, between Ethonal, forced induction and nitrous the hp has returned in a big way and now we can really go FAST. LONG LIVE THE HOT ROD!!!!!!
Thanks Zl, I agree it took the OEMs more than 20 years to learn how to make power again. Computers helped. AG
Always worth noting that right as the EPA regulations were killing power manufacturers were also required to start reporting horsepower with all the accessories and exhaust attached. (a '60's car with a SAE gross 350hp might only rate at 315hp or whatever under 1970's SAE net standards)
nice videos very detailed and understandable
Thanks Roger. AG
Hey Mr. Gold, I'd like to share additional experiences with you and the viewers with my 11.6 to 1 stroker project car. We spoke before about my running 93 on the street with good success as long as I stay out of the secondary's (tunnel ram 600 vac). Race gas needed for WOT, (drag strip). Another problem with this setup is not getting what you pay for. Not all gas stations pump 93 from the 93 tanks. I've had multiple experiences with what seemed to be 87 from a 93 pump, as well as more than the 10% limit ethanol fuels (causing sever lean condition). There's a financial incentive from wholesale to retail to cheat with this. That can be a disaster for those of us trying to push the limit of compression. Then there's also the possibility I won't hear the preignition causing damage over time. So for the customer builds and those who want reliability don't push it. I only did for the pure gear head itch to see "what if". My car is a rolling experiment to satisfy the mind. My next experiment is a methanol/water injection set up that will be triggered with secondary opening. I believe this will allow WOT on 93 octane. Now that you you stoked my interest with these compression facts and theory I'll go back and enjoy your previous video's.
Great comments Bobby, I wish I had thought to mention the issue about the risk of not getting the octane you are paying for. Thanks so much! AG
Welp. Guess I'm going to leave well enough alone at 10.5 static (~9.5 dynamic). Never even considered I might pump 87 octane into my tank without realizing it.
I’m wondering how much of a difference “chamber softening” or polishing and spark plug selection make on an engine’s resistance to knock and pre-ignition. Have you ever quantified that for your engines? Great video by the way!
Thanks Nate. spark plug selection sure does, I meant to mention it in the video but it slipped my mind so thanks for reminding me. I also missed discussing quench, I will try to correct that in future videos. I have looked at chamber softening info but never applied it. Good points. AG
@@goldsgarage8236 What is quench exactly?
Any and all of those factors will and can cause major swings in a max effort engine build exercise caution and diligence you should have a good time
@@seanmclaughlin7415 - quench is the area between the piston and the cylinder head surface that get very close together with the piston at TDC. From what I’ve heard, it is very critical on a Small Block Chevy style engine but not as critical on an LS. I’ve heard that a tight quench is a free boost to compression ratio but never have seen it quantified or measured versus knock/pre-ignition. Would be an awesome Richard Holdner or Engine Masters episode.
@@natez0690 Thanks for responding. I saw a video that Steve Morris did on quench and how they approach this. Basically, it is more trial and error more so than math, but math is involved. Steve designs a conical shape with the combustion chamber on the side where the piston meets the flat of the head into the combustion chamber. Also, he gets the the piston to actually touch the flat safely to maximize quench. Obviously the DIY’er doesn’t have the equipment to do what he does, or maybe there are other ways to achieve this.
If you are running that static, then you have to adjust the valve timing events and match those events to the crank shaft degrees to where you are lower than 8:5.1 dynamic compression., run richer, timing, etc. which negates running it in the first place.
Good point Sean. That is why I stay within my 160-180PSI for my street engines. Thanks for the input. AG
I built an ls6 1970 model 454,it preferred better fuel than pump gas but it was fine with 100 octane prop plane fuel but it finally melted a piston due to detonation.
Thanks Dave for sharing your real life experience. AG
I'm a new subber, try to like and comment on all vids I like. Cheers from Calgary Canada.
Thanks for subscribing John, Cheers back and watch for more content. AG
I delt with this all through the 80s and 90s
Advancing the timing is just creating the same pressure at tdc. What someone running high dynamic compression really should look at is mitigating heat spots even with higher octane.
Thanks for the comment Jar. AG
got a good set of world cast heads with the 72cc chamber with the steam holes for $500
Thanks ve3, viewers can contact you through my channel if they are interested. AG
Using a cam with the correct amount of overlap should help, light car with maybe 2500 stall tight converter, 350 to 370 gears ? More overlap bleeds off compression at low rpm, where most problems occure !
Thanks for your input Peggy. Actually the later IVC of higher duration cams bleeds off compression. AG
I have a 440 12.5;1 mopar been running 104 plus with 93 for many years no problems. For hard racing I run race fuel and still have steel heads.
Thanks for sharing your experience Mopar. All good info. AG
I call engines "motors" all the time so that I can see who is a newbie and corrects me. Are you doing the same with your "steel" heads? Because I can assure that all classic American water cooled engines had Cast Iron block, cylinder heads, exhaust manifolds, ets. Steel has pure iron in it and 1,2,3,4,5% carbon blended homogeneously in it. Cast iron is pure iron with more than 5% carbon, a bunch of impurities, and silicon. Silicon makes it so the "excess" carbon precipitates like rain out of humid air - after the iron is poured/cast. So it's like tiny chocolate chips of pure graphite throughout the part. Some car crankshafts are forged steel to resist breakage. Most truck engines have cast iron crankshafts because the connecting rod journals are way harder and resist wear 10X better than forged steel .Lastly when you melt cast iron it gets really fluid and fills out a cheap sand mold exactly. Steel kind of has to made into giant rods called "blooms" and either some bitten off and hammered into a part or else the whole thing gets made into a battleship gun barrel or bridge part.
Thanks Patrick lots of good information here. I am guilty of using the wrong terms too even though I know better. A motor is an electrical device. An engine turns chemical energy (fuel) into mechanical energy and heat via combustion.
I haven't heard some of the steel terms in a while.
In my corporate career I worked for an integrated steel company (Algoma Steel) for 34 years and retired as a General Manager in 2004, then consulted in the industry for many of the major steel companies in the world including US Steel until a few years ago.
At Algoma we made about 3 million tons of steel per year via the integrated process, pelletized iron ore, coal (refined as coke) and limestone produced raw iron in a blast furnace, also known as pig iron, about 3% carbon. The pig iron was then transferred to the steelmaking shop and mixed with about 20% scrap and refined in 350 ton BOF (Basic Oxygen furnace) a batch process using 27,000CFM of pure oxygen for about 20 minutes. That reduced the carbon content to about 0.10-20% depending on the application, further refined in an LMF, (Ladle Metallurgy Furnace) and prepared for continuous casting and subsequently rolling down to
@@goldsgarage8236 Ah, good - you know the deal, then. I am a genetic hillbilly and I hereby grant you license to say "My Mopar Motor has Steel Heads" with a straight face 1) because it sounds cool 2) impresses women and kids. 3) Creative lying is a time-honored hillbilly art form : )
thanks Patrick AG
Get good cylinder heads with good combustion chambers, that helps in being able to run less timing, today's fuel releases its energy alot sooner.
Your turning strategy with high compression engines must mirror that of an engine running forced induction.
What does a 700 hp Hellcat run for fuel???...91-93 pump!
Remember 14.7 to 1 is not the right AF ratio to tune with any more, you must take into consideration that Ethanol content, and make the overall tune richer.
All good points, thanks Duane and sorry I missed your comment until now. AG
Good info.!
Thanks for commenting Rick.AG
Very well explained! Thank you!
Thanks William, glad you enjoyed the video. AG
I've seen other similar video's, and each time one of the most critical issue's that neglected all together is cam timing. Without that, the conversation is mute.
Thanks for your comment Chris. AG
It's not just in your compression ratio, at least 30% of it is in your cam timing, with overlap and duration - and is overlooked by a good percentage of people. I guarantee you could take an 8:1 compression ratio engine and put too much cam in it and have it ping.
True,,a low duration or stock cam too far advanced so the intake valve closes too early will build more dynamic compression
@@rodfonda3248 all the talking about static and finally someone bring dynamic thank you sir
Thanks Chuck, you are right on. I remember hearing many engines ping if the conditions were right. Thanks for your comment. AG
E.p.a definitely set us back , go from 11.5 to 1 compression in late sixtys to 11 to 1 in the 2000 .
Thanks John, do you remember service stations had two sets of pumps for a few years, finally the leaded pumps were gone.AG
@@goldsgarage8236 Wish we could still have leaded. Remember the long lines during the oil crisis?
Certain days you could or couldnt get gas . Couldnt give away a BB car
Great discussion!
Thanks Chris. More to come. AG
How do you feel about fuel additives that increase octane? And is there any you can suggest I ran sunoco 102 octane when I lived in Florida I could get it at the gas station I'm back in Louisiana now and all I can get is 93 octane I would go E85 but they are few around where I live. The closest is about 30 miles away
Boostane is a quality octane boost. All the better tuner shops I know swear by it. Tuning 1000rwhp modern muscle cars.
@@pockets5628 thanks for the info
Sorry Richard, I don't have much experience with octane boosters myself but it looks like Pockets does. AG
Thanks for the info Pockets. AG
@@goldsgarage8236 I use VP or Torco additives..store bought stuff is snake oil.
That sounds great but in Ohio cam2 12.00 dollars a gallon for 110 in my 572 r Chevy I’m getting 3-4 miles a gallon
Sounds like an expensive ride. Thanks for the comment. AG
Pretty sure u can run 12.5-1 compression if u do these 3 things . Crank Trigger, Camsharft Specs & Coil near Plugs. And perfect tuning
Thanks Robert. AG
@@goldsgarage8236 my pleasure. Phone froze last nite . So reposted this morning. Enjoy your weekend
I'm fairly sure Chevy had Serious 100 octane minimum Warning sticker on the High compression 12 :1 L88 427 even with that Outrageous long Overlap/Duration solid Camshaft....How do you get Around that 93 octane problem ??
Thanks Tom. You would have to mange it for sure, less timing, driving style, keep the RPM up etc. It might not be worth the trouble, but it is probably doable. AG
We ran 11.1 aluminum heads, 402 and 454 bbc on 93 pump gas through the 80s.
thanks for the info Paul! AG
The hot rods back in the day were killed by the EPA and government. Now, they tax our property that we own free and clear. I guess we need taxes for certain things, but it's way overboard, in my opinion. What do I know? I'm just a hard-working American trying to do good for myself. It's sure seems to me that they take a lot more than is needed.
Thanks for your thoughts IronMike. I think most of us would agree. AG
"𝘊𝘢𝘯 𝘺𝘰𝘶 𝘳𝘶𝘯 𝘺𝘰𝘶𝘳 𝘚𝘉𝘊 350 𝘰𝘯 11:1 𝘱𝘶𝘮𝘱 𝘨𝘢𝘴?"
Iron head/domed piston L46 or Lt-1? No likely. Been there done that, didn't work if you put any timing to it.
Small chamber Aluminum head/near zero deck flat tops? Absolutely.
We built a 357 with a hair over 11:1 compression for my friends 1980 Z28. The heads are ported big valve L98 113's with 58cc chambers. He's been driving it hard and auto-crossing on 93 octane for almost 6 years now with zero issue. We tried some Sunoco 100 octane when we were tuning it on the chassis dyno but power still fell off above 34 degrees total timing.
Thanks Czech, all good information. The 406 that i am currently building has 11:1 Static Compression but the cam with 68 degrees IVC ABDC bleeds off enough compression so that the cranking pressure is 180 PSI. I think we will be OK, watch for the dyno day coming soon.AG
@@goldsgarage8236
In my experience a 406 will often fair a bit better at 11:1 than a 350 would if running the same heads because you don't need domed pistons to get there. Depending on gasket thickness, deck and quench height, you usually end up running a slightly dished piston. With Vortech heads it's almost a cake walk. The chamber design actually likes less ignition timing.
So the actual data shows. Delayed combustion timing DOES NOT MAKE MOREPOWER. Optimised combustion timing for the fuel, compression ration, fuel air mix, and combustion chamber geometry. Will produce the most power. With modern fuels which burn faster, more completely and cooler then the old leaded fuels this optimal timing is much earlier than the old leaded fuels. Moving the timing out of this optimal range (up or down) will frist lead to less power and ultimately engine damge if you take it too far. Now power is produced fundamentally from the explosion produced by the combustion of the fuel air mix, the more efficient and the more potential energy in the fuel air charge the more power can be obtained. So more compression on the other hand means a more efficient burn and thus more available power (up till you run into pre-ignition problems
Thanks for watching my video and commenting. AG
Basically what's going on in any motor is timing. The camshaft controls that . But at the end of the day , cranking psi will determine what octane rated fuel you need . The rest is preference. I recommend finding a reputable engine builder ,
Thanks for your comment. AG
Sure you can run a pump gas at 12.5:1, plenty of e85 out there at 105oct. Build the system to that and you can run it no issue
Thanks for your comment doomman. E85 is one solution for sure. AG
I like the videos I like real tech . Why is it that no one talks about crevice lose
Thanks for your comment evilj, not sure what you are asking? AG
@Gold's Garage crevice loss , in the combination chamber .. sorry auto correct
Thank you for your knowledge and video's USA 🇺🇸
And thank you for watching and subscribing, it is what keeps me going. AG
There is a big difference in using this type of engine at the dragstrip do a burnout run the car drive to the pits and shut it off compared to running the same engine with the same fuel on the street in traffic and stop and go in say 95 degree heat for a hour or more with idling at traffic lights
Thanks Gloria, good point. My good friend Dave Seabrook once coined the phrase, " you don't drive these cars, you manage them". I think it applies. AG
@@goldsgarage8236 l can tell you l have a 2011 Camaro SS with a new GM Performance LS3 495 crate engine with milled and CNC ported LS3 heads 11.1 compression ratio that runs on pump E85 it has a load of upgrades and l do treat the E85 with Lucas safeguard ethanol fuel conditioner and stabilizers 2 ounces to every 5 gallons it only requires 1 ounce for 5 gallons but you can't over treat it just to be safe l do not miss buying expensive 100 octane fuel and mixing it with expensive 93 pump
Thanks Gloria, you are deep into the science of fuel management. Please continue to share your knowledge and experience. AG
@@goldsgarage8236 E85 is cheaper than 87 octane about 20-30 cents a gallon but burns faster so it doesn't last as long less miles to the gallon E85 burns cleaner with less carbon build up in cylinders and on pistons tail pipes tips have a yellow gold color at the tip not like gasoline that is dark brown or black engine runs slightly cooler on E85 also pump E85 is 99-103 octane but the summer blend E85 is on the higher end winter blend on the lower end winter blend is 67-72 percent ethanol summer blend is 75-78 percent at the pumps tested at Gate gas station at SR 56 just east of interstate 75 in central Florida on the west coast seems to have a higher ethanol content than Thornton on US 19 in Palm Harbor Florida by 6-8 percent according to my friend who tests it when he gets it and ethanol is what they use to increase pump gas octane so if you took pure none ethanol 91 octane gasoline and mixed it with 10 percent pure ethanol it would raise the octane to 92-93 octane calling pump E85 is a misconception because my friend that tests it has said he has never had a ethanol reading above 78 percent ethanol has had ethanol readings as low as 66 percent ethanol the only way to truly get 85 percent ethanol is to buy expensive 5 gallon cans from a race fuel company and it should be 105+ octane but its expensive vs pump E85
More valuable info, thanks Gloria. AG
I run a sbc on pump gas with 13.7 to 1 it's cam timing not ignition timing
Thanks for the comment Tom. AG
My car is VW 1.0 TSi 3 cylinder, turbo-gdi, it says minimum octane rating - 91 octane, recommended - 95 octane (EU Standards). Am I ok with 91 octane if I drive very sedately and not go above 2.5K RPM's?
ps - the engine has compression ratio of 10.5:1. Thanks!
Thanks for the question Saul. I am not an expert on this type of engine but typically modern engines use a knock sensor to detect detonation, then the computer will adjust the timing accordingly. I think you are safe, however with reduced timing it might lose a bit of power with the lower octane fuel. Hope this helps. AG
I do have a question I have a 498 Big Block chevy I have about 12.5 comp.with a lock out Dist.with iron heads .if a have a 11.5 air fuel ratio what should the timing be to run 100
Thanks Mark, That sounds like a race engine. I think that is something you would have to test for, preferably on a dyno. Start on the conservative side. Looks like you are rich enough. AG
On the dyno, I would hazard 35 to 39 degrees would give the best power curve, but I wouldn't expect much more than a 10 HP difference between those numbers, and quite possibly an inverse relation as the timing moves up to the best peak number. (trades losses at the start of the run for gains at the end)
Additionally, you'll be losing everywhere with that rich an air/fuel unless it's an octane deficiency requirement. 12.8 to 13.2 is a normal "best numbers" ratio.
@@yarrdayarrdayarrda 36 t0 38 degree of timing I really can tell any differnamts the ets were the same .
If I go to a 12.8 to a 13.2 are thete going to be some lean cylinders like in the 14s ?
Static compression means nothing, dynamic compression does. If the cam timing, combustion chamber shape, piston crown shape, ignition and knock control ( if equipped ) are correct you can run pump gas with a lot of static compression. Ferrari currently runs 14.5 to 1 static compression in their 812 Superfast, a 6.3 liter V12.
Thanks Hoost, good points. AG
If it's running Aluminum heads they lower the compression because they are an effective heat sink
Thanks for your input Chief. AG
E85 not always worth it, Not all e85 are equal either. 2 gallons of e85 equals 1 gallon of gas.
Thanks for your comment Paul, sorry I missed it from a month ago. I don't have much experience with E85. AG
30% more ,, not 100%
Ok try paying 12. Dollars a gallon for cam 2 110 octane
Hello, may I ask your opinion on ethanol fuel on carb’d engines. I always used premium ethanol free gas. Now ALL gas in Canada has been mandated to 10% ethanol (as of Jan 2022). I was told on a casual cruiser that eventually, the ethanol would degrade performance and eventually destroy the carb. What are your thoughts? In your experience, is this true? Are there any additives that you’ve found that actually combat ethanol issues? Also, if all grades of fuel have 10% ethanol, is there any point in running premium? Thanks
Thanks for the information J.R_, I did not know that. Prior to that there was a sign right on the pump for Shell 91 that it contains no ethanol. Now I know why the sign is no longer there.
Also, Shell now has 93 Octane?
There mist be a technical explanation why fuels with the same ethanol content have different octanes, but you have to use the higher octane fuel if your engine needs it.
I think that some of the negatives about ethanol are overstated and I don't think it will destroy your carburetor.
One of the negatives that is real is that it evaporates over time and so if a car is stored for long periods the engine has to crank over for a while to refill it before it starts.
This is a problem for our hot rods which are typically stored during the winter.
Lets keep the conversation going, if anyone ahs more information on this subject, please weigh in. AG
@@goldsgarage8236 Thank you very much for your opinion. I've been using aviation fuel since they added 10% ethanol at the pumps to all fuels in Canada as of Jan 2022. Aviation fuel is high octane and with added lead. I think it may be well suited for high performance carb'd engines (not sure about the added lead which all aviation fuel has.?.?). Our local airstrip will sell av gas to classic car enthusiasts. But at $2.55 a liter, cruising gets pretty pricey. So that's why I've been wondering about using the pump gas with the 10% ethanol. Only thing I can think of, may be to drain the fuel in the tank if the car sits over winter. Thanks again for your opinion. I really appreciate it.
I have had no issues with my carb about 40k miles with the 10% ethanol fuel. I’ve even ran mix at times with regular pump gas and 1/4 tank or 1/3 tank of ethanol. Holley carb in matching numbers 68 RS/SS Camaro 350 Muncie 4 speed 115k original miles.
Does octane boost in cans really work ?? Does it do harm to carburetors and fuel pumps ??
Thanks Richie, I don't have much experience with octane boosters. I build engines that don't need them.
I think they do work if you are diligent about mixing etc. They are also not cheap. AG
If you buy the good stuff. Auto parts store octane boosters, no . Garbage,
I have a 427 12.5 cr do you think VP octane booster mixed with 93 octane pump gas would be safe to use they claim 10 numbers in octane increase, that would be 103 if it's true thanks just subscribed
Thanks Anglia. I don't have much experience with octane booster. I have a recent video about thinks you should do to run high compression on pump gas. you might find it helpful. AG
Thanks, maybe you could do a video on centrifugal advance vs lock-out on detonation on high-compression engines using pump gas.
Yes VP in fine, used thiers for 20 yrs. TOrco isnt bad either. Bought a 6 pack last yr, 120. Worth it as I dont drive much
@@gordocarbo Sounds good thanks for the info.
I've noticed when using the Wallace Racing calculator to figure cranking compression they show gauge pressure & cranking pressure. Which figure is best to use? Mopar engine shop Hughes Engines recommends 165 psi for iron heads & 195 psi for aluminum heads. Any comments on that?
Thanks Ragingbull. Dynamic Compression Ratio is a theoretical number. Compression pressure is an actual number. I would go with cranking pressure. AG
@@goldsgarage8236 Thanks for replying.
The reason they give two pressure numbers on this calculator is one is gage (not corrected for atmospheric conditions which includes the absolute pressure). If your around sea level / below 1K feet altitude and ambient / under hood temperatures are not super high then the gage value can be trusted / used against the norm values people speak about for safe DCR / safe CCR values.
Something that these calculators do not consider well is the “VP”-index value (below the Wallace calculator they added a clickable link that describes VP calculation and how this needs considered separately from just DCR / CCR or measured cranking pressure.
If you decide to make another video on this topic you may want to research the “VP”-Index (YT won’t let me post a link but, there is a clickable link on this topic under the Wallace cranking compression calculator)….theres multiple sources that talk about VP-index but, I’ve not seen any of the common calculators people use to estimate DCR / CCR or cranking compression include it.
If my SBC TRW L2311 pistons says 13.4 compression with 64cc heads what will the compression be with 76cc heads?THANKS
If you know the other factors like bore, stroke, dome volume etc you can just recalculate it with the Summit online calculator. 10 cc should be about one compression ratio go my best guess it about 12:1. AG
@@goldsgarage8236 ok Thanks
@@goldsgarage8236 great videos
You can get away with 11.1 with aluminum heads old school. 93 octane
100 octane might do it.
You won't make alot more power going from 10.5 pump gas to 12.5 1 like maybe 20 hp for loss of pump gas.
I agree, thanks Paul! AG
9.1 aluminum headed 496 87 octane much more HP and tq.
Thanks more gear. That is a good and safe way to go, there is no substitute for cubic inches. AG
E85
Thanks Allan, it is definitely an option. AG
Count me in
Thanks Jim. AG
With a lazy combustion chamber design on a BBC, sure, you can run it on pump gas...
Thanks for your comment Dave. AG
Nice Name. :-)
Thanks Allan. AG
Nobody runs 87 octane that I know of because it has that S(#(t ethanol in it that completely wrecks anything with a carburetor and because of fuel separation of ethanol/ fuel and then the water.. One minute your running ethanol and the next low octane fuel because they actually use the Ethanol to bump up the octane and when it separates its bad bad bad! Every hot rod guy I know runs 91+ octane fuel non ethanol and that is perfectly safe for 10.5;1 and some 11;1 cars that are light! Yes weight of vehicle makes a difference in spark nock!
Thanks for your input Larry. Weight of the car is an issue for sure. I wish I had remembered to mention that in the video. AG
Need more gear.
No you can't run it on pump gas of old days
Race fuel is for poor tuners
Thanks for your comment Tom. AG
@@goldsgarage8236 old ridge runner race truck my S10 not ben dynoed but I'd say likely over 500 hp
Great channel Allan 👨🏽🔧👍🏽
Thanks so much Paul. Please keep watching and commenting. AG
Where u from. And how old are you ?
originally Sault Ste. Marie Canada. Now living in London Canada. Born in 1948. AG