I bought an Accel super ram and it came with 24 lb injectors and a 58 MM Accel throttle body. I've been told the 58 MM is too big for my stock head/ cam 91 GTA 350. Is this true? Should I use a 52 MM one until I put my ZZ4 cam and 1.6 ratio rockers in, then slap the 58 MM on?

Any knowledge on this would be appreciated. Thanks.

 

Even with rockers and cam it'll be more than you need, but you have it and it wont hurt anything to put it on so go for it.

You'll need a lot more cubes or lots of RPM's to get to the point that a 52mm TB becomes a serious restriction, either way you'll need serious heads too.

 

The only issue with bigger TBs is that the Accell Enrichment routines are setup for roughly the amount of opening of the stock TB.
Basically you may get a lean spike when tromping it open because there will be less added fuel Vs the TPS position and the throttle blade opening.
(More opening for air per TPS movement than before)
Tuning in the chip can correct for this if it is too much of a problem on the setup.

 

That makes sense to me. I do plan on having a chip made by pcmforless FYI, I assume that will fix any issues and I should able to run the 58 mm TB I already have then, correct?

 

If it was tuned for your car (via recorded data and not just a guess), yes it should be fine. You'll know if its not ok, it'll be sluggish on acceleration when you first step on it from a stop or steady cruise.

 

Yes, I would prefer a dyno tune but every dyno tuner within 2 hours of me is out of business it seems.

 

The 52mm is overkill imo.

 

FWIW
I did back to back testing of a stock vs BBK 58mm TB ; over 30 runs on same day
Stock TPI L98 w/ ZZ4 cam / intake mods / headers.
There was no difference in performance. 60ft times ( 1.7X ) were identical indicating no loss of bottom end.
Definately not a good bang for $$$ investment but also did not kill engine perf as some claim

 

"also did not kill engine perf as some claim"

That has been my experience as well.

 

I've got a 58 on my stock lb9 (i got it from a junkyard for 20$ when my orig. stoped returning to closed) and it threw my tune way off. I have to turn up the fuel pressure so that it's horribly rich at idle just to get a reasonable a/f at high rpm. Yes i know i seriously need to quit bs'ing and learn to tune.

 

Thanks for the responses guys. I am going to stick with the 58 MM my super ram came with and I am having a custom chip made as we speak by pcmforless.

 

good choice with pcmforless....used them many times with great sucess. I would agree that 58mm is probably too big for stock engine/heads...wll cause slow throttle response compaired to the 48mm, but it will run with it on there, probably won't see any performance gain from it though...I probably wouldn't worry too much about it.

 

As I noted above , absolutely no difference in throttle response with 58mm
I drove home from track with 58mm on and only comment I will make is, off idle tip in was harder when tickling the throttle , say to move forward in traffic like when at lights because of the heaver spring BBK use on their TB's.
Hard to apply just enough pressure on pedal without going too far . Other than that could not tell any difference over stock TB .Have that TB on my 480Hp 383 and still gives the same problem

 

I noticed difference on a stock motor with throttle response, but on my built motor I did not. and I've not had any problems with the the BBK, that's the same one I have, no issues with mine....

 

Yours has the improved throttle linkage arrangement where the cable pulls on a quadrant giving better pedal "feeL"
The early TPI cars have a straight pull at the linkage like on a carb