Ive noticed others complaining about this. including tony mamo talking about it

Is there a fix for this?

It just feels like it doesnt open AS fast as the old 78's we had...

Opinions?

 

What?!?!?! Man I hope not, my new build includes a ported LS2 TB by the Mamo man himself. But then again, the rest of the motor is sized and prepped accordingly.

Steve

 

I'm thinking flow velocity for the specific application is in play here.

 

I've read the throttle blade ref voltage is slighly higher for the C6 than the C5. This causes the throttle blade to not open as fast or to 100% with full throttle on the pedal.

I'm pretty sure Tony does a port job that takes this into account and puts back the full flow and throttle response, but he'd be the one to answer that.

I use a late model Nick Williams TB with no problems. BLACKTOP2000 uses an unported LS2 and is quite happy with it's response and power. Of course we did a full tune on his car from the throttle body to the VE table and spark, along with mine.

If you want to check, take the airbridge off and with the motor off and ignition on, have someone press the gas pedal slowly from 0 to 100% while you look at the blade, or set up a mirror to watch it.

 

I believe Tony Mamo stated in a recent thread that the 90mm throttle body actually gave a much better throttle response than the stock 75mm units? He said that a ported FAST 90 didn't give up a great deal of power to a port FAST 78, but the throttle response of the 90 made it feel like it made a lot more power?

 

Hope some tuner might chime in, to correct me ? u need to change some kind of parameter in tune to work properly 90mm in C5, something reading like .52 or .225 something, i read it long time ago i totally forgot, use search function.

 

 

ive read about changing a parameter in the tune also.... can anyone chime in on this?

 

 

Guys,

Relax....a STOCK LS2 TB sucks for throttle response (and hurts power), but properly ported they are very crisp and offer more SOTP than any ported 78.

BUT....in stock trim they are horrible....extremely lazy for lack of a better word. You need to push the pedal to almost a third of its travel before the engine wakes up and responds.

A ported LS2 TB will make your car feel like you picked up 100 cubic inches based on the additional responsiveness over a stock unported version (mainly because the unported version is weak-suck).

The reason this is the case is due to the design of the housing surrounding the TB blade which is essentially buried in aluminum (very small air gap) for the first 20% or so of the throttle angle....then you finally start uncovering some air which feeds the engine and allows it to respond. They did that for the conservative folks to detune the throttle a bit making it more progressive if you will (less responsive) in the lower portion of your throttle positions where you spend the bulk of your time driving. Problem is they got waaay to aggressive with that situation IMO killing half the fun for the performance related crowd (but employ the right guy with the grinder and all your problems thankfully fade away....LOL).

A properly ported TB removes alot of that excess material which in turn allows alot more air in the engine at much lower throttle positions but you can easily go too much (ask me how I know....LOL) and the throttle response can almost be a hair trigger....fun sometimes but a PITA long term. There is a fine line and only experience and experimentation will get you there.

Hope this helps

Tony

PS....Steve, you have nothing to worry about!

 

Whew!!!!

The only thing I have to worry about is my wife finding out how much I am spending on my "project". LOL!!!

 

That I would have to agree with you on!

(And I cant fix that situation with a grinder )

 

How much to port an LS2 tb?

 

I went from a TM ported 90 to a completely stock TB on my H/C Z. With respect to Tony, he's overstating the difference. It IS noticeable, but very slight;not 1/3 throttle like stated above, more like the first 1/4 INCH of gas pedal travel. I got used to it, then got tired of it, and mildly ported my new TB myself. I don't notice it at all anymore, and I hardly removed any material.

 

Did you just polish the rough casting at the inlet of the throttle body?

 

Zee...

I disagree and Im not saying that to try and bolster my porting revenues....I have experienced the difference as have many others. Its quite noticable, especially with an optimized car and a lightweight driveline that immediatly snaps to attention (my car has a clutch/flywheel combo that weighs 20 lbs less than stock).

In fact here is a quote direct from you last year (and the link) when you did the initial swap to the ported TB....

http://forums.corvetteforum.com/show...119&highlight=

I know you had some tuning gremlins later on that unfortunatly you never resolved, but I have countless dozens of ported LS2 TB's out there working flawlessly. The right tune is paramount for seamless drivability when stepping up into a more effective larger diameter TB.

-Tony

 

Tony have you done any testing with the TPIS modified LS6 intake where they cut the snout off and epoxy a 90mm opening on the LS6?

 

Just put my FAST combo on today and there is no slugging... It is ported along with my 92mm Intake though.

With a little 224/228 114 a.k.a. the Tony Mamo special and all boltons it made 469/432

 

The problems inherent in a stock unmodified LS2 TB would still exist (lazy throttle response)....it doesn't really matter which style intake you bolt it to. The FAST with its larger plenum and bigger runners will make more peak power than the modified LS6 intake, but concerning the TB and throttle response, all of the parameters I described above still apply. If you want the snappy throttle response, porting the TB is an absolute must.

-Tony

 

Yeah, the tuner never could get it right. To exacerbate the problem, after adding the FAST combo, the clutch started to go. Kind of the straw that broke the camel's back. He couldn't do a full throttle dyno run without burning up the clutch, and a previous local kid with a HP "Live" program had locked up the PCM. Tom Wong over in Vancouver, WA. did the best he could, but he did say the TB was ported too much; whatever that means. It did run great at everything but hot idle. Pulled super strong, and was more sensitive than stock. I do stand by the minor difference, with the caveat of "once you get used to it".