Tuners ! Throttle body question for a Gen I. Why the Taper?

[viperrt96]

I've been looking for some minor mods to do to my 96 RT10. I already have Roes high flo cats and a borla catback exhaust (roes smooth tubes and KN filter). I'm going to do a light weight flywheel this winter. I need to know if this mod is either value added or NON-value added. I have in the past bored out a few throttle bodies (GM LT1/LS1). Can't give any dyno numbers but they seem to help my ETs in the past. Didnt hurt anything anyway. I pulled my throttle bodies off and measured them. They are 60mm at the inlet and taper to aprx 55.8mm at the intake side. Why the taper? Only reason I can think of is possibly a sound requirement or ? We all know what and how a lesser restricted airbox will sound when you are at WOT versus stock. I know the older Vipers had that reverb box or? air inlet attached to the intake assy. I have access to a machine shop so machining these are not a problem. I even went as far as buying a extra set off Ebay. I feel comfortable boring these out to 62mm each. I dont want to go any bigger for two reasons. There will not be much material leftover if I go any bigger and really what will I gain. Anyone done this? I know they make bigger throttle bodies but if you dont do the other mods (heads,cam,headers,ETC)why waist your money. This Mod is a little bit more than a 10% increase in airflow versus stock so I would think it would be a gain. Just wondering if anyone had done this. Thanks

 

[joe117]

I've never used larger TBs. I have seen more than a few posts about it. You could do a search and read about it.

What they say is that if you go to larger TBs with a stock engine, you will lose power at the low end and not make up for it at the top end.

 

[viperrt96]

I did a search before posting. All were about installing 70mm TB's. Most post were also for the Gen II. I know 70MM is overkill for most including me. If smooth tubes are a 10hp gain I'm pretty sure going from a TB that is(stock) 111.6mm (total) displacement to a 124mm(total)thats over 10% gain. I'm sure it would make a difference. I just want to know if anyone has done it. I've wrenched on many a cars and seen many a TB's. I've never seen one choke down like these are. It's enough to me that might make a difference and at the same time not be overkill. Never know, you may still be able to have both. (low end torq/ top end)

 

[99 R/T 10]

I have a set of 62mm TB's I was going to put on my car along with a set of RR, but changed my mind(went with a newer car). I was going to go with TB's and a set of Arrows. I have seen the HP increase(dyno slip) of 44RWHP and 41 RWTQ. If your interested in the TB's let me know.

 

[joe117]

"I'm pretty sure going from a TB that is(stock) 111.6mm (total) displacement to a 124mm(total)thats over 10% gain."

I'm not getting the numbers. Can you help me follow you?

 

[Torquemonster]

Joe I think he's doubling them because there are two... so stock would be 55.8 and the 10% gain would be going to 62 (x 2 = 124)...

But I could be wrong

 

[viperrt96]

You are right Torguemonster. I was putting the numbers together x 2. (2 TB)

96 R/T 10 - 44rwhp and 41rwtq for 62's and RR. Sounds like a good gain. What type of RR are people using? Ratio and vendor type?
Thanks

 

[99 R/T 10]

The numbers are from a Gen II, did it with T&D's and 65mm. Results will vary, but I would guess the pick ip in HP and TQ would be somewhat close, just not as much.

 

[jp]

I would not do the TBOs unless yre doing the heads and cam. You will loose bottom end. I'm still running with stock TBOs on my modified engine, and my engine pumps out 643hp and 664 ftlbs.

 

[MaxedGTS]

I would not do the TBOs unless yre doing the heads and cam. You will loose bottom end. I'm still running with stock TBOs on my modified engine, and my engine pumps out 643hp and 664 ftlbs.

Have you ever tried bigger TBOs and see if you pick up any hp?

Max

 

[jp]

No, I've worked with the air flow (speed) through them instead of the area.
Airbox, cones etc. That's were you find hp.
/JP



[/QUOTE]Have you ever tried bigger TBOs and see if you pick up any hp?

Max

[/QUOTE]

 

[CAS]

Use stock TB's unless head/cam work is included with it - you will not gain and stand to potentialy lose power on a stock motor.