I bought a FAST intake and a LS2 TB to install on my H/C C5. I can't affort to get them ported right now, so I had planned on doing some porting to the TB and installing.
Now I am hearing guys say that the LS2 TB is a little "lazy" at part throttle. I have an auto with stall and gears, but it has GREAT part throttle response now (almost like stock until you nail it) which makes it a ball to drive around town. I don't want to adversly affect that in any way. Should I rethink the LS2 or do some porting on it and take a chance.
It seems odd that Chevy is using them on the new C6s if there is a "drivability' Issue.
What is the feedback of those who have installed them?
Thanks

 

There was a second of hesitation on my unported fast90/ gm 90 combo. But it was mainly if stabbing it from like 1300-2000 rpm's. Drove like a pissed off banshee after that

 

Were you able to get that tuned out, or did you try porting the TB?
That type of hesitation would drive me CRAZY

 

Have you contacted any porters? The TB porting is usually not much.

 

There is nothing wrong with the LS2 T/B. I think It's taking the rap for bad tuning... I have a FAST/LS2 T/B on my road race stroker and I love it. It performs flawlessly and is easy to tune, especially at idle. I would not port the T/B as you have a high risk of making it perform worse than before and there is little benefit. It's way bigger than you need already. Porting the manifold will yeald some flow improvement with less risk... Start there first.
Shirl Dickey
SDRE

 

comparing the LS2 TB with the TPIS 90, for example, there is a difference. The TPIS 90 is more crisp and has easier graduations of power. I don't know how to better state it than that. You would have to drive the two to notice the difference. The characteristic only is experienced at 0-20 mph , or part throttle, and then after that, there is no difference. I don't think "lazy" is a good term, because it is not a bog sensation, but rather a harder pedal if that makes any sense.

Many tuners prefer the LS2 TB to tune, but, any 90 TB can be tuned well from a competent tuner.

The LS2 TB has the advantage of an OEM look and has that neat stealth factor that the TPIS unit cannot offer. If you were to paint your FAST/LSX intake black, even Corvette enthusiasts might not pick up the mod.

 

Thanks for the input guys

That is how the guy that posted a few days back described it. Tony Mamo (Who really seems to know his stuff) replied that the issue was not anythng more than the TB needing a "clean up". He stated that all of the LS2 TBs seem to have that issue stock, but ported they were just as crisp as any of them, but at an obviously lower price.
I know what you mean by more throttle, and that's what has me concerned. I have a SY3500, and it seemed to take "a little more throttle" aftre I installed it. After I installed my Dart heads, it was like a different car. It seemed all I had to do is "brush" the petal for it to re-act. I REALLY don't want to lose that if possible.

 

My LS2 TB does have a lazy, hard off idle feal to it. Before with the LS6 in and ported shaner TB, it was crazy fast. It is not slow now, just needs more firm presure off idle. My tuner is awesome, and we will get it a little more crisp. I am happy with the looks, I just hoped I would gain more on top, as I am stuck @ 460 it seems:o
Dave

 

Mine works great but I'm not sure if it was ported. And I had it tuned before I drove it.


DH

 

The LS2 TB in stock trim has ALOT of extra aluminum in front of the throttle blade. Just examine one closely and it's plain as day to see. Then slowly open the throttle blade and see just how much you need to move it to start seeing a significant "window" of airflow that the engine is capable of ingesting. End result....you need more gas pedal travel to finally get to the point that the engine becomes responsive (finally responding to the extra air and of course fuel the injectors provide). That is why some have noted the pedal as lazy. A properly ported TB will remove alot of the restriction and extra material allowing the blade to uncover additional air sooner increasing throttle response as well as picking up 3-6 additional RWHP because the more streamlined TB now flows alot more air in total which is beneficial at high RPM when the engine has its largest appetite for airflow. You can ruin a TB by overporting it so there is a balance that has to be met. I just ported one for a guy with a stock C6Z06 and he really liked the crisper throttle response and also found 6 additional HP to the tire with no other changes. A very good gain in HP per dollar (less than a couple of hundred spent) but the increase in "seat of the pants" and throttle response is the larger benefit you get to experience every day. It's a no brainer in my opinion and makes the much larger dollars you just spent converting alot more worth it (assuming you stepped up and bought a FAST 90 / LS2 set-up). Bottle Fed....I will send you one with a money back guarantee....I know I wont be seeing it again....LOL

Hope this helps paint a clearer picture of whats going on....

Tony

 

I just had a new FAST 90/LS2 Shaner ported 90 combo installed and tuned on my C5 H/C, Lvl 5 A4 w/3200 Vig, & 3:73 gear application.
Absolutely no HP gain whatsoever, and in fact lost a little rwhp on the dyno. No problem I said, take it to the track...get the real numbers.

Although I have traction issues(Nitto DR's)...they are the very same traction issues I had before I installed this setup.
I will say the Fast 90/90 setup gives you SOTP feel, and seems more torquey/responsive, at first. Because of that feeling, and in spite of the dyno, I was expecting to see a drop at the track in my e.t.(I was hoping for a tenth) and maybe even a slight increase in trap times...wrong.
Absolutely no increase whatsoever, in any dept. All of my times, which always remained pretty consistant, showed no significant change after the install.

As always...I ran my usual 11.9x...7.6x...& 1.7x's. Didn't lose any, but didn't gain any either, unfortunately.

I had always heard this setup worked best on strokers/big cubes...guess I had to find out the hard way. I let a friend, who said he gained 24hp on his H/C 346, m6 sway my judgement.

Good news is...I got what I paid for...the tuner never promised a gain of any kind, though I asked him for a real world avg(now I know why he wouldn't answer me)...and I have what I need for a future stroker setup one day.

Good luck with yours though...you never know.

 

Can't say that I wanted to hear that.
I'm wasn't expecting any hugh hp increases, but that's a lot of money to spend for NO GAINS I've heard that most of the big gains come on the larger cube motors, but there are a lot of stock cube guys posting some nice dyno #s with the 90/90 swap over on LS1tech...

 

Yes...it is a LOT of money for no gains. Live and learn I guess.
All I can say is, the install and tune was done by one of the best tuners in the DFW area.
And yes, I know about LS1tech. My *friend* I told you about, is a regular over there, and he is one of the posters stating a nice HP gain with the Fast 90/LS2 90 setup. Maybe it was his post you read?

 

Sorry to hear that....Your results are very much the exception, not the rule as they say. I can only guess there are some other issues at work here because while the gains certainly vary based on all the factors involved, a FAST 90 set-up, even unported, consistantly shows gains usually to the tune of 10-15 RWHP (5-10 more with the manifold and TB ported). I have personally been involved in at this point close to a dozen "A-B" dyno tests against the stock LS6 and the LS2 intakes and even a bonestock 346 showed about a 12 HP improvement (over an LS6). The last test I was involved in on Westech's engine dyno showed a 27-28 HP improvement going from an LS2 to a ported FAST 90....what's crazy is that was with the SAME TB. The LS2 is definately weaker than an LS6 intake....about 5-7 HP or so.

Anyway....it seems you have covered your bases regarding the install and tune but there is definately something amiss with the combo (or the intake) if it has not provided you with any gains. Saying the FAST isnt a better piece because of your results is like saying bolting in an aftermarket cam wont provide any additional power gains....while for some reason your combination might not have picked up in that hypethetical scenario, too many others have done the same with very much the opposite results....its no different with the FAST. I might even be inclined to contact Comp if your that sure you cant find any additional ponies....maybe there is a problem with your intake although I think that is highly unlikely.

Good luck either way...

Tony M.

 

Hi Tony. I've seen your posts over on LS1tech, so I know you're a knowledgable person, on this stuff.

I don't know what it is, except depressing, but it is what it is. Seen several others on here post about no gains also...not sure of their individual circumstances, and am certainly not knocking the product, only saying that on my car, no evidence could be produced to support any increases.
Real Performance Motorsports, who is known to provide some great tuning, especially on A4's around here, did the install and the tune, and could not get anymore out of it.
I provided them with a 21MC dyno showing 400+ rwhp with my old LS6/ported LS1 TB combo, but when I left there, the best they could muster was approx 385 rwhp...and you can see that I have taken it to the track for the real world numbers...not to mention I had just been to the track the month before, the install, and had run an 11.93...then went right after the install, and ran an 11.94...so very insignificant changes there also. I don't know what the answer is.

I have about 15,000 miles on my H/C install...and about 10,000+ miles between the 21MC dyno and the Real Performance Dyno. Don't know if that is enough to explain this or not.