On a stocck 87 TPI 350 with 3.73 gears and flowmaster system with no cat. Would the motor make more power with a 52mm throttle body. It also has the air box gutted, home made ram air, and the screens cut from the MAS. A hypertech thermomaster chip has also been installed.

Thanks and Regards,
G

 

Kind of overkill if you ask me. The stock 48mm TB will do just fine until you start making more internal mods

 

very little difference. I think your money maybe better spent on a good set of headers at this point

 

No.

 

What size TB would you guys recommend for a 383?

 

if you have nothing done to your engine....that it probably won't do to much. I installed one on my car when I installed headers, full length exhaust and ram air..and it made a pretty noticable difference. There are people on here that will tell you that you don't need a 52MM unless your pushing 1 million horsepower though.

 

The throttle body shouldn't be your biggest concern for the induction. Runners, plenum, base manifold porting will yield you more power. Also, you could get headers for nearly the same price and get a very noticable difference.

I would go for headers then fix the induction.

 

What was your before and after e/t or dyno #s?

I ran a 48MM tb on my aftermarket TPI setup well into the 12s before I finally got sick of TPI. I might have pulled off a few high 11 second passes, but I wanted to sell out while I could.

-- Joe

 

I never said I dynoed it...but for the butt dyno, throttle response was much quicker...I'm glad I went with the 52MM

 

48mm is more than fine for what you got.

Spend the funds on something else.

I still run a 48mm unit on my 385 motor.

I could use a bigger TB for sure, but it still runs like a ***** ****@, so maybe one day when I got some free cash I will burn it on a TB.

Until then I will need slicks as a first priority.

 

I think on the TPI setup its a waste of money. I tried all sorts of porting, tb's, airfoils, etc. Nothing seems to help improve over the immediate 90d turn the air takes into the runner, then the long journey down around and over to the head.

IMO, 48MM is fine for any TPI setup. Perhaps on a miniram, lt1, i'd say otherwise.

-- Joe

 

Thanks for the info guys.

The stock 48mm body only flows 635 cfm. The 52mm folws 750 cfm. So it looked as though you could build a litte more power in the upper rpms 4000 - 6000 range.

I am planning on a set of Hooker shorty headers. I'll probably do that next month.

Eventually, I'm going to add a stealth ram, better heads, and bigger cam.

Any recommendations on heads and cam for the L98?

Regards,
G

 

This is similar to the opinions I received and decided to stick with my twin 48 mm throttle body. I seem to remember on Horse Power TV on weekend mornings they bolted a larger throttle body on a car with a small block and dynoed it before and after with no appreciable differnece in horsepower. Somebody else may be able to remember that episode.

 

according to a CFM calculator for a carb.. a 350 at 6000 rpm at 95% VM you only need: 577 cfm obivously going to be a little differnent depending on the exact setup.. but I would say there would be no need for a larger TB on your current setup.

 

yep, I do!

No big difference.

....allthough some people will tell you a stock TPI needs a million CFM throttle body.

hehe, just kidding 84!

 

52mm is good if your stock tb is worn out. Just remember that to really work properly the tps tables in the prom need to be updated. this will cure any tip in throttle problems from the larger TB. when I went to a 52mm occasionally I would get a code ( highor low pressure/voltage or something ,I think code 32 or 33) this can be cured with upping the tps voltage (backyard fix) but once my chip was tuned throttle response improved significantly, I know seat of the pants doesn't count with this crowd, but the mid range did feel beefier, and there was a little more top. But, of course this was on a car with L98 home port heads/intake +a XE264HR cam car ran strong. beat a few stock tt supras on the street and freeway. 52 mm worked for me. But this was by no means the first mod, probably the last mod I would do in a build up.

 

I guess the consesus is that it does make a difference, but not worth the money.

I'm fortunate to have a machinist friend who bored my stock TB to 52mm for free.

 

If I use everything else the same on my 383 with DesktopDyno2000, the differences come up as follows for the 3 "standard" TB sizes:


48mm (635cfm): 406HP @ 5000, 504TQ @ 3000

52mm (750cfm): 410HP @ 5000, 506 @ 3000

58mm (930cfm): 415HP @ 5000, 508TQ @ 3000


Not much difference, and almost all only the very top end.

Hope this helps a little bit.....



- Ye Old Phat Phart, Vern

 

Thanks again guys. The plan for the winter is to add headers, 1.6 rockers, the 52 mm throttle body, and nitrous.

I got the 52 mm body from ebay for $ 170.00, so I thought it wasn't too bad.

Regards,
G

 

I bored mine out to 52MM when I still used TPI.. I can say my 70MM monoblade has me hooked now..

-- Joe