How would this throttle body relocation affect performance?

This cold air intake for Ecotec engines relocates the throttle body from on top of the manifold, pointing up at the hood, to a few inches away, pointing forward. It seems to me like this would do two things:

• Increase plenum volume, which is probably good
• Increase the distance between the throttle body and intake ports, which is probably bad

Anyone have a more concrete analysis? I think the elbow looks kind of cool, but it just strikes me as one of those things that if it was a great idea, more people would be doing it.

Generally with these things I point out that if it made an appreciable impact then the OEM would have done it that way.  But it depends on why you want to install it as sometimes the OEM doesn't design vehicles for the uses we put them through 

My question with these items is simply this:

Are there repeatable and verifiable results with this item being the only change?

Unless they provide that (by actually performing proper dyno testing as well as real world tests), I'm generally not interested.

Mr_Asa said:

Generally with these things I point out that if it made an appreciable impact then the OEM would have done it that way.  But it depends on why you want to install it as sometimes the OEM doesn't design vehicles for the uses we put them through 

Usually I fall into this camp but it may have been done this way because this engine had most of its usage as transverse and this looks like a longitudinal application? Cheaper to make one intake fit both than to optimize and have different?

It increases plenum volume but it does so in a way that is not really beneficial, I don't think.  A larger plenum allows the air to slow down more between the throttle body and the runner, slow air is high pressure, non directionally specific air.   Normally larger plenums need smaller throttle bodies and vice versa because of this effect.

  With the throttle wide open there should be no difference, and if the throttle is not wide open there is an easy avenue for more power 

I don't think that was done for more plenum volume, what it does do is allow a larger radius turn down to the intake manifold by eliminating the throttle body's height.

Pete. (l33t FS) said:

I don't think that was done for more plenum volume, what it does do is allow a larger radius turn down to the intake manifold by eliminating the throttle body's height.

That's what I assume as well. If so, that probably has a bigger impact than anything else. FWIW I've driven a car with much more tubing than that added between throttle body and intake manifold, and the throttle response change was barely noticeable.

In reply to dps214 :

You've rallycrossed with Detroit guys... Armstrong's Miata had the throttle body on the supercharger inlet... and the supercharger was mounted over the exhaust manifold, ducted to the original intake manifold.

Extreme example, I know, but you could hear the severe throttle lag when he'd let off and the engine took a while to use up the high pressure air in all the plumbing.  Not the best throttle response for a chassis that demands precise power control.  He'd be halfway into the corner when the engine finally started to decelerate!

iansane said:

Mr_Asa said:

Generally with these things I point out that if it made an appreciable impact then the OEM would have done it that way.  But it depends on why you want to install it as sometimes the OEM doesn't design vehicles for the uses we put them through 

Usually I fall into this camp but it may have been done this way because this engine had most of its usage as transverse and this looks like a longitudinal application? Cheaper to make one intake fit both than to optimize and have different?

Correct. In a FWD application, the throttle body faces up and forward, and attaches directly to the air box. RWD applications need some kind of elbow and tubing to reach the front of the car. This elbow looks nicer than most, but relocating the whole throttle body seemed like an odd choice to me.

I think Pete is on the right track that getting the throttle body out of the way allows a larger radius bend. That was probably the idea behind the design.

I don't think I'd worry about much of a change from adding distance or volume.  If you're really looking at the nitpicky details in a razor-edge race vehicle, it might be worth exploring, but it's not nearly as important as if you had a carbureted induction where the air is carrying significant mass of fuel with it.

I'm more concerned that it might direct more air to the back cylinders and less to the front cylinders.

Either way, red was a horrible choice for color. That should be semi gloss black considering the rest of the enginebay.

MadScientistMatt said:

I'm more concerned that it might direct more air to the back cylinders and less to the front cylinders.

There's a decent-sized, symmetrical plenum tucked under the runners. Distribution between cylinders shouldn't be affected at all.

iansane said:

Either way, red was a horrible choice for color. That should be semi gloss black considering the rest of the enginebay.

Well, this picture is from a Slingshot--they're not really known for subtle, tasteful mods.

I don't understand why they didn't do an elbow off the stock placement of the throttle body like the Solstice CAIs do with the same engine setup. Unless hood clearance is ridiculously tight?

EDT (Forum Supporter) said:

I don't understand why they didn't do an elbow off the stock placement of the throttle body like the Solstice CAIs do with the same engine setup. Unless hood clearance is ridiculously tight?

Yeah, maybe hood clearance is really tight there on the Slingshot, I don't know. Maybe they just did it this way to be different, and charge more. The elbow is an aluminum casting, so it's not a cheap part.

I've seen the air distribution issue crop up with elbow intakes on four barrel carbed manifolds that had been converted to EFI - even with a large plenum, the runners on the long-radius side get more air. A divider in the middle of the elbow can help a lot.

Assume that is the DDM Works conversion. Dave knows what he is about - I expect that it works as advertised and that moving the TB has no negative effect.

The big risk I see is less about airflow and more about cantilevering a very heavy, bouncing object off a plastic manifold that was never intended to be loaded as such. I obviously can't say that it will or won't fail like that, but I'd personally be keeping an eye out for cracks if I did that mod.