Throttle bodies

[SapphireGTS]

I did a search, but knowing you guys opinions change.

Who has done throttle bodies. Im looking to do something to tie my mod urge over until I do NOS or S/C.

And suggestions for some good ones to replace these
Italian jobbies?

 

[JonB]

There was a long and passionate debate on the OLD BOARD a couple yeasr back. Hi-brow talk of Velocicty, CFM, cross-section, honing, pooling, stratification, etc etc. The consensus was:

T/Bs by themselves will do little. They are best chosen with roller rockers and/or headwork. Even then, DONT go larger than 65mm unless you are approaching 600HP. Then go 68mm.

Without serious flow mods, you will simply rob low-end grunt and relocate it higher. That is, move your power band peak from lower to higher RPMs. Numerous anecdotes here of 70mm TBs seriously disappointing those who only added that mod w/ headers.

Just hone the TBs you have ! ORECA ran 50mm restrictors, and 35mm in some races !

1.7mm RRs w/ 65mm TBs are a big bang SOTP improvement on G-2

 

[RockyTop]

Jon B knows of what he speaks. I installed headers, 3" exhaust w/ stock cats (since changed to high flow), modified stock air box and 67 or 68mm throttle bodies. I now realize I just wasted my money on the TBs without further mods. (which I may do when the waranty expires). While the dyno said I did not lose any low-end grunt at the 2,200-2500 level (which is where the dyno began sampling), my seat of the pants impression was that from 1,000-2,000 I lost some jump. As I do no straight line driving (twisties and daily street only)it's not that big a deal. If I decide not to do more mods, then I'll just re-install the stock ones.

If lap times is what you are after and you have the budget, get a well sorted out brake system. The Viper days racers et al swear by the Stop Tech system. Wish I had the jack.

I can honestly say that the best mod I have done to my car was to adjust the nut behind the wheel. Apologies to Fred "Driving School" Kinder for stealing his thunder ! The Panoz school at RoadAtlanta, the Justin Bell school, Skip Barber are just a few. VCA members get discounts at some. Check it out !

 

[MES]

Anyone try and port the stock TB? results? I'm thinking of getting a stock set ported by David Wilks to go along with some new heads. He claims good results from them, but don't know if I should.

 

[kARLUG]

I sent my t/b's to David Wilkes and had them ported and polished. He did a nice job and my throttle response
is better. I didn't do any before and after dyno's but I
would recommend this inexpensive mod. good luck!

 

[King GTS]

65mm Billett should hold you over.

 

[Gavin]

I have 65mm, 1.7 rollers, headers and all the good pipes
Not much difference in performance until the revs get up - then she hauls - 60mph and above I pull away from the stockers.
Example Laguna Seca - stock Viper was maxing out at 119mph down the straightaway - me 130mph.

My belief is, if you are not putting the car on the track,with the aforementioned modifications,then forget about it.

Hope this helps.

 

[varanus]

Gavin- I think you just drive better than the rest of them!

 

[Fred(DrivingSchool)Kinder]

Throttle bodies show no HP or torque gain on motors with the the stock (except for being extrude honed), Heads ported and polished By Caldwell, More aggressive cam, T&D roller rockers.
After the motor engine duno break-in Dan Cragin removed the stock TB's with larger TD's result 1 HP change on the engine dyno.

 

[WCKDVPR]

Gavin,

130 - that's it?

 

[9 seconds]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>ORECA ran 50mm restrictors, and 35mm in some races !

<HR></BLOCKQUOTE>

[small rant]I see this comparison from time to time and it means nothing. What compression ratio do they run? Also, they use a different intake, different heads, different engine management, turn more rpm's.....I'm sure there's others. [/small rant]


OK.

Don't change the TB's unless you do serious MOD's. That mistake has been made many times already.

 

[Gavin]

Varanus - thanks for the compliment - horsepower is what gets you down the straightaways - doesn't take much driver ability.

Mike - that was 130 thru the corkscrew !!!

 

[WCKDVPR]

A bit of data on the effect of restrictors - I spent some time last year crewing for the American Viper Racing team. During that time I had a lengthy discussion on the horsepower their cars make, the two different intake systems they were running (the long and the short runner 10 throttle body), and the influence of restrictors. This discussion included John Caldwell as he was around from time to time while trying to develop the long runner intake.

The prototype long runner 10 throttle body setup made approximately a 10-20 hp and a peak of 50 lb-ft of torque over the familiar short runner setup (which has approx 650 hp and 650 lb-ft) that we are used to seeing on the GTSR's. This is with the ALMS restrictors in place. Without the restrictors, the short runner engines make in the neighborhood of 800 hp. The restrictors accounted for a loss of at least 150 hp - on these cars.

This doesn't mean go put big throttle bodies on your car as I agree with the other posts here that the stockers are your best bet until you get really deep into the modifications (heads, etc.) or go stroker.

Gavin, of course we were talking about the corkscrew, where else would you go that slow?

 

[Wolf]

I was thinking of getting the larger throttle bodies myself last year, but I found out through this forum and also from my Viper tech that there really isn't any gains from the larger throttle bodies. In some cases, if your engine isn't heavily modified (roller rockers, ported and polished intake, etc) you can loose horsepower and torque by putting in the larger throttle bodies. However, there are gains to be made by re-machining the stock throttle bodies. There is a small lip in the throttle bodies that cause turbulence in the intake track, if you have a chance, take a look inside and you will see where the throttle necks down and there is a lip there that opens back up after the throttle plates.
After my throttle bodies were remachined, I took it out for a drive and definately noticed an improvement in throttle response and the whistle that normally comes with the smooth tubes got louder....which is good/bad depending on who you are.

If you are in the California Bay Area, drop by Ted May's shop and he will show you what I mean.

 

[SNKBYT]

I had my stock throttle bodies polished by David ***** . I installed 1.7 arrow rockers and the polished throttle bodies at the same time. I gained 38rwhp. I have Edelbrock headers,Sean Roe hi-flo 3" cats, Borla exhaust, Modified K@N airbox w/BTR intake tubes,and modified computer. Now 479rwhp/525lb.tq Definately makes a difference if you have good air/exhaust flow thru the whole car. *THIS POST WAS EDITED BY THE MODERATORS*

 

[99 R/T 10]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
*THIS POST WAS EDITED BY THE MODERATORS*
<HR></BLOCKQUOTE>
Just curious as to why? Bad word?

 

[MadMaxx]

I don't think the guy is well "taken" on the site

James