52mm vs 58mm TB

[rrubel]

I have a chance to get a package deal with an Accel Super Ram (with or without base; I'm not decided) and a 58mm throttle body. Would the 58mm be overkill for this intake without cam/porting changes? Would the 58mm be a good investment to put on now for when I *did* do more mods, or would it actually adversely affect performance? The price is such that buying this guy's new 58mm would be cheaper than buying another new 52mm.

I need to know this soon because others are lined up for the same deal...

Anyone want to trade a 58 for a 52?

Thanks.
[RICHR]

 

[vader86]

I dont think you need it for a 350, you dont even really need it for a 383. A 52mm will work just great for the 383, but even then some people have reported idle issues.

 

[Ken]

52 will suit you fine Rich, until you get up to around 500 hp, then the 58 will be necessary. That engine would have to breathe very deeply to take advantage of the 58. Too large of a throttle body could actually hurt your performance.

_ken

 

[rrubel]

Thanks, guys. This is what I was looking for. As my goal right now is ~320 HP and ~400 lb-ft, this would be overkill.
[RICHR]

 

[sothpaw]

Can't say if the 58mm would actually hurt. But I know from
following this that it won't help, as the others said. In fact,
I'm convinced that the 52mm won't help until you do the cyl.
heads.

 

[Vettelt193]

sothpaw, the 58mm can hurt performance because the blades are so big they can get in the way and hinder the flow. This is only true because of the lack of airflow through them on an underpowered engine... if you have an engine that can handle the 58mm, it certainly wouldn't hurt

 

[Mad-Mic]

a 52 would help on a stock motor. it would help it rev faster and breath better than the 48. the 58 is too big it flows over 1100 cfm where the 52 is about 750cfm and the 48 about 600 cfm

so in all honesty if you had a quadrajet on your motor and you stepped up to a 750 double pumper that would improve alot but if you put a twin 600 holley on a tunnel ram what would it do? fall on it's face.

so the 58 unless the motor is spinning fast enough and hard enough it will just fall on it's face. pressure is only as good as it is pushing and or pulling which a motor does both. if you think about it this way if you open your mouth as wide as you can and inhale as fast as you can is that comfortable? not really but if you take a nice deep breath thru your nose (smaller cfm) and that feels natural and more healthier. now if you did the same with a little straw like a twizzle stick you'd turn blue in the face. this is just like a motor in our vettes got to have the right application to achieve the goals set forth. you have to have pressure balance on both sides of the motor.

heads will not just warrent a 58 mm tb with out cam, intake, and more less a total rebuild with higher compression.

 

[WhalePirot]

My 52mm BBK breathes my 406 just fine; to red-line. The engine puts out about 550hp.

If the deal is so good, buy it and swap the 58 for a 52 from some guy who is impressed by the numbers or one who has figured he needs it.

 

[Mad-Mic]

rich sorry i got tied up today lets get together some day this week just let me know.

Mic

 

[rrubel]

'sawright, Mic... I got busy as well. It's probably moot anyway as I won't be selling my TB to anyone - it'll be sent back as a core.
[RICHR]

 

[grumpyvette]

a 52mm throttle body will effectively handle most sbc combos,now , don,t get me wrong, they even use a stoch 48mm TPI throttle body from the TPI corvettes on the 502 bbc with factory EFI, so even a stock 48mm will work, but also keep in mind that EFI is FAR less effected by changes/increases in air flow that a similar change in carb. size. now that being said its not at all unusual for a corvette to get BOTH a slight INCREASE in hp and a SLIGHT LOSS in throttle response when swapping from a 48mm to a 58mm throttle body. but also keep in mind that MOST intake systems runner flow rates and EFI M.A.F. sensors are so restrictive that the engines cant use the extra airflow!
the HOLLEY STEALTH RAM (especially if its ported and used on aftermarket cylinder heads) is one of the few that can use the extra airflow that a 58mm throttle body provides