L98IROCZ89

It's been a long time since I've been on here and I need some advice. Within the last two years, I swapped my L98-MAF/700R4 for a ZZ4TPI/T56. I kept most of the stock TPI except added SLP runners and SuperRam base. I had several SES codes and got a custom chip burnt which makes the car run pretty well.

I am thinking about changing the top portion of the TPI to Superram upper, many tell me it won't matter since I have a super charger. True or not true? Is this a pretty easy swap that me and a buddy can change?

Also, do these stock throttle bodies get "worn out" over time? I am having trouble getting the throttle return to idle when I am not pressing the gas pedal. I've tried all kinds of tight return springs with no luck, it just makes it that much harder to get to WOT. Should I try to do something with the current throttle body or swap it out for a new? In that case, stay with a 48mm or upgrade?

Would either of these changes require a new chip? I just paid $350 to get this one a couple months ago and now I am thinking of the above changes.

Any advice on either or both would be appreciated. I hope I am not violating any forum rules since I was on here last (it's been awhile).

Thanks!!!

IROCWPB

What's in the way of your butterflies closing all the way? I had my plenum/throttle body off the other day and cleaned out the area where the butterflies sit in their closed position and got them to sit a lot tighter.

pandin

Check the bushing area of the thorttle body. A little looseness and a little carbon on the back of butterflies can hang it open.

As to the plenum Callaway twin turbo used stock plenums.

L98IROCZ89

That is interesting information. Thanks, I'll start with trying to take the throttle body apart and clean it before spending money on a new.

As for the plenum, you don't think there is benfit to a SuperRam upper as opposed to the stock plenum with SLP Runners and SuperRam base? I figured I'd get: bigger plenum, shortner runners for more high end HP and little low end TQ loss based on user feedback, port matched upper and lower. Your thoughts on that?

My tune is pretty good at the moment... if I changed to a SuperRam upper do you think I would need to tweak the tunning?

pandin

In theory: A bigger air box takes longer to fill. SC is filling box and engine at the same time. Might cause a little lag at snap throttle open. When throttle snaps shut. Takes a little longer to rev down (bleed pressure from box).
Stock plemuns are usally equal in size to the cid of the motor. So the time would be very short, at higher rpms. The time it would take to go from say, 10 psi boost to 10 in hg. Just a few turns of the crank.

Air in a box will tend to lower peaks and fill holes as the pressure or vacuum pulses up and down. A smoothing filter so to speak.