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In another thread a few of use have been discussing our cars going into safe mode. One solution which seems to have helped at least a few people is to install the LS3 throttle body. It is a direct swap for the LS2 version and seems to be more reliable and is definitely less expensive by far. I've had intermittent P2135 codes and safe modes and nothing else has made it go away for good so I tried the LS3 throttle body.

Today I drove the car with the new LS3/gold throttle body on it. It started and idled very well. The throttle tip in from idle was decent, maybe just barely less aggressive than my ported LS2 TB. It ran and drove just great. I still have an AC low idle issue which was a side effect of the new tune that the tuner needs to fix. It doesn't die, but when it is warmed up and the AC is running it tends to idle too slow (about 500-600) and surges just a touch. So, that is an issue with the tune, not the TB (which I kind of figured).

I blasted through the gears (1-4) three or four times, hitting redline in each gear and I never got a code or reduced power mode. The LS3 TB whistles just a bit at full throttle, kind of sounds like an old Quadrajet when it is first opened up (which isn't an entirely bad thing).

Now my dilemma is deciding whether to have the LS3 TB ported or not. If I do decide to have it ported, I'm going with one of the companies who does them by CNC. The ported LS2 TB I have was done by hand and while it was done well, it really doesn't look like they took off as much material as they could have.

But, I was looking at going with VMax for the porting and it looks like they entirely take out the lip that is in front of the blade. Isn't that usually a problem, doesn't that potentially cause idling issues and can't it make the off idle tip in become very aggressive? Or does that only happen if you start porting into the section where the blade comes to rest?
 

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I hate to say it but it's not worth porthing... You will feel no-difference. I'd raise the idle to 800 rpm and you'll be good to go.
 

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if you port it, the only difference you will will is quicker response on throttle tip in because the lip will be removed. You wont see a power increase because the the hole size and throttle blade stay the same size.
 

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Discussion Starter #4
Is that all that lip does, delay/soften the off idle tip in?

And I don't know about a power increase, but by removing the lip you ARE increasing the size of the opening. I just know that when I went from my stock LS2 TB to my ported TB I noticed a nice improvement to throttle response. Though, to be fair, I did also install a ported LS2 intake at the same time and I'd suspect the ported intake had more to do with the improved overall feel of the engine, but I'd suspect the improved throttle response was due to the TB.
 

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Is that all that lip does, delay/soften the off idle tip in?

And I don't know about a power increase, but by removing the lip you ARE increasing the size of the opening. I just know that when I went from my stock LS2 TB to my ported TB I noticed a nice improvement to throttle response. Though, to be fair, I did also install a ported LS2 intake at the same time and I'd suspect the ported intake had more to do with the improved overall feel of the engine, but I'd suspect the improved throttle response was due to the TB.
Everyone that "ports" their TB claims to "feel" or "notice" a difference. That's a placebo. No matter how wide you manage to make the opening, it will still be bottlenecked to the engineered size of the throttle body blade. (LS1 = 78mm) (LS2 = 90mm)

The only way to get a performance gain is to increase the size of the bottleneck, but in doing so you will create a vacuum leak since the blade will be too small for the enlarged opening.
 

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supposedly it is a dyno-backed modification.

i would imagine having a smoother transition helps somewhat. you may get a few more CFM of air. but, not much compared to an actual increase in bore size.

all the same, extra CFM flow with a throttle body may net you absolutely nothing if your engine doesn't need it.
 

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This is completely anecdotal with absolutely no scientific/engineering backing, but I think porting actually hurts performance after my recent experience. As much as people like to say these cars aren't tuned for max performance, there are thousands of hours on engineering and research done to them. I'd assume there's a very good reason that "lip" exists. I had my previous TB ported thinking the same ... it's gotta help since you're allowing more air in by removing that lip, seems to make perfectly reasonable sense, right? Since switching back to a stock LS2 TB with the lip, the car idles better, has better response while driving around town, have much more audible intake noise and have seen no difference in SOTP feel during WOT pulls.

If I were you, I'd do back to back drives with the ported TB vs the LS3 one to really see if you feel a difference. See if you really feel a difference or if it's just in your head. For me, I'm leaving it alone as I honestly feel the car runs far better with the lip.
 

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Everyone that "ports" their TB claims to "feel" or "notice" a difference. That's a placebo. No matter how wide you manage to make the opening, it will still be bottlenecked to the engineered size of the throttle body blade. (LS1 = 78mm) (LS2 = 90mm)

The only way to get a performance gain is to increase the size of the bottleneck, but in doing so you will create a vacuum leak since the blade will be too small for the enlarged opening.
this. The placebo effect is the fact that the lip is gone, that block air in the low throttle percentage regions, and allows more air in with less throttle input....making it more responsive feeling, at first throttle press. overall power is not gained. They have shown anywhere from 0-10hp gain. you can dyno a car back to back and do nothing and see that much difference.

Do I do it? yes, for two reasons:

1) its a free mod for me because I do all my own work, including porting heads and building my transmissions. so porting a tb is easy for me.
2) I welcome the extra throttle response.
3) and if for some magical reason theres a gain...well i have it automatically. I really dont think you gain and hp....but i'd still do it. I do not count that as power added. How bout someone go to the track and test it?

yea, I added one more. oops. last minute.
 

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this. The placebo effect is the fact that the lip is gone, that block air in the low throttle percentage regions, and allows more air in with less throttle input....making it more responsive feeling, at first throttle press. overall power is not gained. They have shown anywhere from 0-10hp gain. you can dyno a car back to back and do nothing and see that much difference.

Do I do it? yes, for two reasons:

1) its a free mod for me because I do all my own work, including porting heads and building my transmissions. so porting a tb is easy for me.
2) I welcome the extra throttle response.
3) and if for some magical reason theres a gain...well i have it automatically. I really dont think you gain and hp....but i'd still do it. I do not count that as power added. How bout someone go to the track and test it?

yea, I added one more. oops. last minute.
I don't like the idea of weakening the structure of the throttle body to gain supposed throttle response and no performance gain. Different strokes for different folks.

(And I know, its not a significant structural weakening, especially not one I should personally care about because my GTO is still NA.)
 

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Discussion Starter #11
Well, I threw my stock LS2 TB back on (not ported) and it definitely feels more sluggish off idle than the LS3 TB. At the very least, the LS3 TB is an upgrade to a completely stock LS2 TB. At least to my butt-o-meter at least as far as throttle response is concerned, I seriously doubt it adds any power.
 

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Maybe i should weld a lip in my nick williams 102. :scratch:

Nope.
Legend says Nick Williams didn't put a lip on his throttle bodies because it would generate too much power.

:wall:

Maybe there was something seriously wrong with my ported TB, but with no other changes, I'm getting a lot more audible intake noise. More intake noise (without any other changes) to me is a good sign that more air is getting pulled in and making more power. Either that or the new LS2 throttle body has a leak somewhere letting in unmetered air, lol.
 

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Discussion Starter #17
Legend says Nick Williams didn't put a lip on his throttle bodies because it would generate too much power.

:wall:

Maybe there was something seriously wrong with my ported TB, but with no other changes, I'm getting a lot more audible intake noise. More intake noise (without any other changes) to me is a good sign that more air is getting pulled in and making more power. Either that or the new LS2 throttle body has a leak somewhere letting in unmetered air, lol.
Well, yeah, if you were having idle problems whomever ported it probably ported into the section of the opening where the throttle blade comes to rest. THAT area is really sensitive to alterations and removing material (thus opening up the amount of air getting in at idle) will most definitely jack with your idle and consequently your off idle tip in.

Honesly, my new LS3 TB feels as responsive as my LS2 ported TB so I'm not sure porting the LS3 would even be worth the time and effort. Maybe.
 

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I remember closing my LS2 TB blade and marking where it sat around the bore with a sharpie, and then again with it the resting position. I was careful not to port in the lines.
 

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I have a V MAX ported LS2 throttle body that I have been running for a few months and just changed to a ported LS2 Manifold. The tip in was much better with the throttle body and more responsive and better throttle response and it pulls harder above 3500-4000 to 6500 rpm.
 

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I had Mamo motorsports port my ls2. I did a dyno test with no changes and it was 8 to 15 hp depending on heat soak and air temp. So anyone saying there’s no data dosent know what there talking about. Don’t get me wrong it’s not much at all but it is more of a crack on tip in and there is a benefit. But there is no way your butt dyno will notice that little of gain.
 
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