The Project

iTrader: (6)

I was wondering which 58mm throttle body is better...the Holley or the TPIS. The Holley goes for $350 and the TPIS for $500.

What is the difference in performance between the two?

Thanks...........

Fast92RS

iTrader: (2)

There both over priced. You can get a summit one for under $300 and its just as good.
http://store.summitracing.com/partde...5&autoview=sku
or one from tpiparts.net
http://tpiparts.net/inc/sdetail/8042

87zjeff

iTrader: (4)

are you using this on that 305? if so, that 58mm throttle body is way to much. a stock one flows enough for the 305 or you could get the 52mm version.

The Project

iTrader: (6)

I'm collecting parts for my next motor (383) Just trying to see if the Holley or TPIS is better.

19redbird89

what about the BBK? I too am looking into the 58mm tb but I have 355 to push it.

87zjeff

iTrader: (4)

that's cool. i was looking at some on e-bay recently and saw some with decent prices(don't remember brand). iwould think the holley or tpis would both be good parts. i have a bbk myself and have had it for about 10 years with no problems.

LT1FUN

As others have already stated, a 58mm throttle body on a TPI 305 is completely overkill. I can pretty much guarantee you won't get anything out of it (performance wise).

I picked up a Holley 52mm a few days back for my L98 and while I did feel a pretty substantial improvement over the stock 48mm, it's only because I've already completely upgraded my TPI system. Ported Edelbrock/Lingenfelter intake base, Big Tube AS&M runners and a fully ported TPI plenum. The largest you can port the plenum area just behind the throttle body by the way, is 52mm. If you try to grind it out to 58mm, you'd end up breaking through the plenum wall itself because the aluminum is not thick enough. Then you'd have to weld up additional aluminum to seal it all up which is time consuming and definitely requires someone with welding experience...

I can't comment on the TPIS T.B.'s but I can on the Hoolley. The Holley unit is expensive for sure, but it's also truly a Grade "A" piece. Easily the best looking T.B. on the market but performance wise, I highly doubt it's better than any of the other throttle body's on the market of the same size. Your basically paying for looks pretty much, since all throttle bodies are basically built to perform the same.

Personally, I'd spend my money on something else if I were in your position. You'd need to upgrade the rest of your intake first before you'd need a larger throttle body. Otherwise, it's just money being wasted. You may even lose some performance if your bolting on a larger throttle body to a stock plenum 'cause all the air entering the larger opening of the throttlebody will basically be hitting a "wall" once they reach the smaller ports of the plenum thereby causing air turbulence.

Upgrade the rest of your intake first. Once that's out of the way, I'd recommend you go with a 52mm.

If you'd like to see pictures of the Holley up close, check out this post:

https://www.thirdgen.org/forums/tpi/...-throttle.html