Oversized throttle bodies... REALLY worth it?

[TheSh111t]

I posted this on another DSM board tonight, but have not had any replys to it yet. I would also like your guys openions on the matter. Here goes:

I was wondering about oversized throttle bodies. I know people say that the 60mm 1G TB is a good upgrade from the little 2g 52mm throttlebody, but is it REALLY that big of an improvment over the stock 2G TB? I still have the sorry little T25 (For now) but watching the boost guage (Autometer ultralite) when I am at freeway speeds cruising at no boost and I punch the throttle, the boost goes up litterally faster then I can count. My boost guage is fed right off the intake manifold (After the TB, so I am reading true manifold pressure like I should). So if the boost goes up as quickley as it does, is the stock 52mm TB really that big of a restriction? What about boring a 1G TB to 64mm, or even an aftermarked 70mm TB or something? I am planning a FP green or ETE32 earley next year (February I hope) with all the required suporting mods, but should I really consider the TB upgrade? By the way, I have a spare 2G head in my garage, and will be sending it to BG cylinder heads next month for a 1G intake match port, bowl work, 3 angle valve job and a street port job. I will also be running an Extreem turbo 3inch turbo back exhaust and extrude honed 1G intake (Already have it). With the mods listed should I consider the TB swap, or even an aftermarked TB all together? What are the negative side effects of running an oversized Tb, it any? Thanks everyone, I realize this post got kinda long.

 

[larryd]

the 1st gen throttle body is supposed to increase your top end just a lil but but nothing huge and I really cant imagine noticing any difference with the lil T25.

 

[TheSh111t]

So what are your thoughts about aftermarket TB's? Are there any direct replacment TB's that are larger then 60mm and bolt right on? If not, how hard if it to make a 70mm TB fit? What cars should I get the parts off of? Like I said before, I am stil running a T-25, but will soon be upgrading to a larger turbo, I'm sure that if I'm going to see any REAL increase in performance, that is when I'll see it. Thanks for everyones help so far. Please keep the suggestions comming.

 

[echo]

in theory it will help, but i'm not to sure that it will be that big enough of a difference. maybe if you are looking for every little bit of help you can get it will be worth it.

 

[larryd]

hee ya go.. read this

http://www.dsmtuners.com/forums/showthread.php?s=&threadid=12988&highlight=throttle+body

 

[paul s]

www.imagestation.com/picture/sraid20/p778afc5071219714bd865b2257f14558/fdbfc2e4.jpg
www.imagestation.com/picture/sraid20/p50aaf8ff888eeae707ddd3f0532c2a3c/fdbfc2e2.jpg
There is two pics of a 1G T/B bored out to 64mm(RC) on a 2G extrudehoned intake. I noticed little more top end and better throttle responce..

 

[CraigB]

Paul S:

The 1st picture you posted looks like your intake is not matched to the TB. Did you match it? Or was this picture taken before it was done?

 

[TheSh111t]

If I'm understanding this correctly, Accufab makes a direct bolt on TB? I can't seem to find the TB you talked about on there site. Could someone post a link to the TB in question? Would going with a 70mm TB really be worth it, considering most intercoolers have a 2.5 inch inlet and outlet? 64mm is just over 2.5 inches, so maybe I should just go with a bored 1G TB. Where can I go to get a 1G TB bored? Thanks for everyones input. Please keep up the good info.

 

[DSMu4ia]

The aftermarket TB's do NOT just bolt on. The bolt pattern is different than stock.

You guys are nitpicking when there are WAY better mods to waste your time on than a bigger TB.

1g TB/Intake Manifold is fine, just rebuild the TB first, and get the intake hot tanked. Be sure to remove all the EVAP/EGR stuff so the intake doesn't end up all gummy again.

There are people doing well over 500whp on a stock 1g TB, and unless you have 3" UICP, I don't see a reason for a larger one.

 

[paul s]

Craig. B
The T/B, intake, elbow and the UIP are 2.5 inches, in the picture the gasket was not enlarged yet plus nothing was tighten up it looks off.

 

[CraigB]

Paul:
What turbo do you have on your car. I put 64mm TB on my friends laser with a 20G and it helped out. Pulled alot harder down low.


I just had 3 TB's bored out to 64mm I going to put new shaft seals in and the sell them.

 

[JET]

A larger TB should only help up on the top end, not down low. I do think a larger TB would benefit up top though. Even though the 1g TB is 60mm, you have to remember that it isn't a smooth shot like the IC pipe. I am sure the butterfly valve causes quite a bit of restriction. The only problem going with larger TB's is that your fine throttle control gets worse. I wouldn't think it would be a big problem up to 70mm, but over that you might start to notice it.

 

[CraigB]

Oh ok I guess you would not have more airflow with a 64mm TB opened to let say 25% over a 60mm at 25%

 

[paul s]

Craig B
Until last month I had 18G, now sold and going little bigger(t3/4), the engine is getting fully build as we speak. I'm hoping for low 11's..the shaft on my T/B is filed down a little..

 

[CraigB]

I have had shafts milled down pretty thin on N/T TB's. But I don't know about milling them on one for a turbo car. I have heard of shafts breaking on the after market TB's

What T3/T4 are you going to run? I have a 60 trim with a 63 AR stage 2 exhaust wheel. I like it, Spool up is not to bad. Plus I have a FWD I don't need a quick spool up.

 

[paul s]

Actually it's an ETE 32 or 42, I will decide when the engine is done in a week or so. Most likely the 50 trim, I don't want too much lag.

 

[CraigB]

Here is a picture of my non turbo 1st gen big bore TB.It is bored out to 64mm and polished and also has new shaft seals that will hold the boost. I still need to clean the outside.

http://www.imagestation.com/mypictu...7bf5c738c4f174/fceadfa4.jpg&caption=photo0021

 

[paul s]

I did my seals last year, they were leaking boost and I didn't know it untill I replaced them and had to turn my boost down. The T/B looks good..

 

[Cody Morris]

Can a 2g elbow go onto 1g TB?