What's it worth? 103mm Throttle body on a factory LS3 Intake Manifold
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- Опубликовано: 30 сен 2024
- We recently tested a 103mm throttle body on a factory LS3 intake manifold to evaluate a question we are often asked - does it add any power. The simple answer is no, not even a little bit.
Here is the write on our website if you want to read about it: gwatneyperform...
Thank you.
Thanks for the money saving info👍
I’m sure if you added heads it would be different.
I just installed a Katech ported throttle body on my gen5 ls3 with SW 2" long tubes, Corsa 3" back, VR "tune" intake. Logged 2.6% increase in airflow at WOT 6000ish rpm. HP gain is debatable, but adding more air is always the goal. I could not feel the difference with my butt dyno at WOT, but low end throttle response increased bigtime. Not impressed with Katech quality...The throttle plate was acid stained and mounted upside down. At first I thought... oh well, no one will see the stained ugliness or upside down etching once the VR CAI gets reinstalled. BUT, I noticed the plate was catching the edge of the body since it was installed upside down so I rotated the plate 180 degrees and it fit perfect. Katech has a fancy website and videos, but quality control is poor.
Glad you got it squared away. That's really the gain to be had with an aftermarket or factory ported throttle body - that response down low. If you look at the factory TB there is a huge step behind the blade that pinches airflow at low blade openings. This is done by the OEMs to make everything nice and gentle, but it sure is boring. TB porters, or aftermarket TBs reduce that step, which makes that early blade opening area extremely sensitive.
Sorry to hear about the less that desirable issues with your Katech. We sell those routinely and I can tell you that as a whole, they are good quality and we have minimal come-backs, no more than any other brand. I can also agree that quality on parts in a very general sense isn't what it used to be, and that surely is frustrating.
Thanks for the info
Do you think you'd have the same results if it was running E85
Yes, it wouldn't change a thing about the airflow.
Shoulda used aftermarket heads and intake manifold.
Well - that wasn't the test. The test was pretty specific criteria - is there value in adding a 103mm throttle body to a factory intake manifold. For that, you obviously need the factory manifold. We've done a lot of intake testing (see below) which left us confident that the intake would become restrictive before the heads, so they were a non-factor. The fact that we picked up zero power and zero change in manifold vacuum is strong evidence that the flow limits of the 103mm on the factory manifold are not the throttle body itself, and the modification is not worth the effort and cost.
However, we also did a big square port intake test a few years back that has a number of different manifold combinations on a heads/cam setup that was designed to really push the manifolds to their limits of performance. Here is the link if you're interested: gwatneyperformance.com/the-ultimate-ls3-intake-manifold-dyno-shootout/
Do you ever figure out what was causing the air restriction? I’m going throught this at the moment.
It's not something we pursued further. This was already a modified and ported manifold, so it's likely just the design of the manifold itself. I don't think you're ever going to overcome that. It's still one of the best Factory intake manifolds to be offered on a late model car, and even untouched they work quite well
Great info!
i am running the GPI SS4 cam and the GPI heads, CAI intake. I have NOT done the GPI intake manifold yet. Do you think with the larger cam and the heads it would make better use of the 103mm TB if I did the intake or should I just do the intake? Intake being the port and rod mod from GPI.
I think this test pretty clearly shows that there is restriction in the intake, but it is not the throttle body. I would expect a 103 mm to gain zero power on the setup you described based on what we found in our testing. The intake porting and Rod mod is definitely worth doing, that will add some Peak power and really stand up the mid-range.
I have a 2014 camaro SS running stock throttle body. With Gpi rod mod intake mangold. I also have heads, cam n e85. Which 102mm or 103mm work better for my setup?
Maybe re-watch the video - we proved that there is NO gain with a larger than stock throttle body with the factory manifold.
@@andrewcammer2535 the 103 and 90 have the same bolt pattern? looks like it just claifiying.
@@TheDevin918 correct