throttle body upgrade?
 

Well, like the title suggests, I'm curious if there are any throttle body upgrades. I would assume that there is nothing "off the shelf" but I'm wondering if anyone has ever gone to the trouble to bore out the stock throttle bodies and put in larger butterflies. Plus, I haven't looked too closely yet, but do the butterflies sit striaght up and down, or are the plates an ellipsis? Also, what IS the diameter of the stock TB's?

Just curious, because I'm planning on doing some work on the intake side of things to help the motor breathe a little easier. I'm planning on sending a spare intake manifold to Extrude Hone to have them polish the inside, and I'd like to see if I can get ahold of a set of phenolic spacers.


Anyways, just curious if anyone has looked into this yet. I realize that they are already generously sized for how big the motor is, but maybe there is an improvement to be had.

If no one has looked into this yet, I would spearhead something myself to see if we could get something done.

Thanks for any help!

got a price from Extrude Hone on doing the intake yet?

I just emailed them the other day, and I'm waiting for their response.

I don't really care how much it costs though, I just want it done. I don't think I've heard of anyone doing it on an SVX yet, but I know it's shown worthwhile gains on other cars. I think if I did phenos, IM, and something with the TB's (possibly also extrude hone) and an intake like myxaplyx, I think I would have some noticeable gains.

The throttle body twin intake throttle plates are 60mm and capable of flowing 900 CFM*.
Our 202 CID engines can only flow 420 CFM at 100% volumetric efficiency
at 7200 RPM.

That said, there are some slight gains to be had, at least theoretically, with some mild porting/port matching.

However, depending on your applications, the exhaust is where you should look.

* Paraphrazing Terry McClain in The Subaru SVx FAQ.

Ok, yeah I figured that they would be more than enough. Seemed like plenty of throttle body for our small motor. Anyways, that's good to know!

I'm still planning on checking out extrude hone though, and seeing how that turns out, and doing before/after dynos.

If it works out how I'd like, I see they do group buys, and I would be willing to organize one if there was enough interest!

When I checked with Extrude Hone they wanted, what I concidered to be a huge amount for their services.:o
And I pass their place on my way to Pgh!
Another Racer also spoke with them and decided against going that route, but we both went with ceramic coatings and Outlaw Engineering phenolic spacers.:)
Tom

I have a set of outlaw spacers on my probe, and I absolutely love them, and I saw in your signature that you had some, so I at least figured they were an option. Looking at their website, I don't see the SVX listed, so can I get something through you Tom, or should I just email them?

"we both went with ceramic coatings and Outlaw Engineering phenolic spacers"
Are there specific reasons other than $ for this decision?

If you speak to Sean at outlaw he can hook you up.
you only need to decide whether you want all five spacers or just the top three.

Is the 3rd the throttle body spacer?

Everyone who is on a budget has to make decisions.:(
It was much easier for me to port and coat the intake manifold than to pay about $200 or so to "hone it".
And when I was done with it it mached.
Throttle body to manifold.
Manifold to stacks.
stacks to ports.:)
I know that the ceramic coating with the spacers lowered my intake manifold temperatures.
Many people have felt my intake manifold and can vouch for how cool it was.:cool:
As I remember Extrude Hone wanted about $300.00 to do both exhaust manifolds, the honing that is, and that was approaching the parts bill, of my headers!
I wish I had unlimited funds and time, then I would have had Burns Stainless built my headers.
For about $2000.00:o
Not the labor, just the parts.
Tom

Yes, and the fourth and fifth are for under the stacks.

FYI,
You get the inside of the intake and stacks glass beaded when you have the thermal coating done as they put the pieces in a giant vibrating tank for the final "finishing" stage of the coating. So, +1 for everything OT has said in this thread!:cool:
-Bill ("Father" of the intake thermal coating mod;):D)

I just figured that I would get the outside of the manifold coated and get the inside honed. While glass beading certainly wouldn't hurt anything, it wouldn't make things nearly as smoothe as the extrude hone process would.

Also thought about getting the outside chromed. That would just look flippin' sweet.

Why dont you take a walk through my locker.
Engine pictures shows the silver ceramic coated manifold. and there are three sections on porting, plus several on the Outlaw Engineering phenolic spacers.:)