legacycentral bbs

any one bored out your throttle body for some more air?

greg

I've looked into it, and it may help, but how much.....not really sure. I think it would be more beneficial on a turbo then a n/a........

what size(s) are the Legacy stock throttle bodies?

I think that, given how restrictive the rest of the intake system is, a bored out throttle body probably won't give you noticeably more power. It would probably make you feel like there's more power, though, since throttle response would change (it would become more "touchy"). That's because a bored out throttle body lets more air through when only partly open than a stock one does. That's how the throttle feels on my girlfriend's Saturn SL2. It's jumpy at low throttle, but 50% throttle and 100% throttle feel almost exactly the same.

A couple companies, like Cobb used to offer these for the EJ25, but stopped because they found it really didn't do much. On the NA engines, the weak link is the intake manifold. Getting an intake and free flowing exhaust make a big difference, but you will hit a point of restricted air flow through the manifold at some point, but this requires headwork and cams before that happens. I wouldn't bother with changing or boring the throttle body.

Saturn SL2 - Throttle body's around 50mm in diameter. Does anyone know how large ours are? With my old Saturn, a 52mm TB helped and a 55mm TB helped even more, especially after I tapered it to an edge and thinned the butterfly plate for better flow. I understand we've got a restriction in the intake manifold that will ultimately be the weak link in the chain but I'm still curious. What size did the Cobb TB's used to be, and how much larger than the stock size? I suppose I'll measure it when I check for linkage adjustment, but anyone know off hand?

Wait, you're saying that a larger throttle body helps on Saturn SL2s? Then maybe my girlfriend's air filter is clogged or something... Better check it. Thanks.

Yeah, the TB helped a great deal with WOT, dropped the Saturn's quarter mile time by 3 tenths going from the 52mm to the 55mm with the taper, n/a. Then again, Saturns have a different intake manifold and cylinder configuration. I had an SC2, same dohc engine different body... did your girlfriend's Saturn lose the resonator and airbox yet? -- because that makes the tb bore more noticable.

lol... send her to www.xtremesaturn.com, bbs just like this one for saturn enthusiasts. I used to be one

Cool, thanks for the pointer, Chris. We haven't done anything on the Saturn yet; she just got it a few weeks ago. I didn't realize the SL2 and the SC2 had the same engine. I think I may go and pop in a new air filter and pull out the resonator...

The biggest restriction on the EJ22T when reaching into higher powers is the heads before the "throttle plate box" becomes a problem.

Now if your talking about the 4 legged intake runner then realize you would have to cut the monster open and reweld. The small increase in CFM wouldnt be enough to matter.

In doing research for my project I found information about flow rates for EJ20 heads and EJ25 heads and associated parts. They basically said the same thing, the money to cut them open and make them flow more would be better spent on some head work (the heads they measured flowed extremely well BTW). Ill try to find the link.

Ciper,
That flow information is posted on the Cobb site. One more than one occasion Josh has said just what you did about cutting the manifold. There is one tuner looking into the new composite manifolds for the EJ25 to see if they flow better. I am anxious to hear how the new composite manifold flows because that may be a short term solution for my needs...

Also, Cobb is working on an ITB solution as well. I will likely be using that on my NA build that they are currently working on. But expect it to be a very expensive, race only, custom option and at least a year off...

Lastly,
Dcoty and his brother are designing a custom manifold this winter for Dan's car. he hasn't said anything about selling them, but if the design works on his car, his arm might be twistable...

but if we are talking about EJ22-T's, the manifold is kind of a non-issue. As mentioned the heads are really the restriction and poor flowing manifolds do allright when you boost a bunch of air through them...