Turbo V Engine - Exhaust Manifold Design

[Brandnew]

Looking for insight on designing/routing exhaust manifolds for a single turbo on a V6/V8 engine.

Lately the trend has been to go with parallel twin turbo but I'm looking to go to a single turbo in this application. Unfortunately, due to the twin turbo trend I'm having trouble finding infomation on the common methods of routing the EM to the turbochargers.

I'm looking for information on the common routing. Do you try to make the two EM's the same length??

I'm planning on modifing the existing EM's for this project if the sizing turns out to be approptiate. Existing EM's are the "collector style" (not seperate pipe "header style&quot. What can be done to increase viability of this type of EM?

Any links/books/information you can provide on the common routing of V6/V* EM's for single turbo's would be greatly appreciated.

 

[furious70]

how much power are you trying to make? If this is a relatively low boost, low hp deal (15psi, 1.25-1.5hp/cu in) then I don't know if it matters that much. Obv. you need a balance tube connecting the 2 sides. I would think trying to get the turbo close to the middle would make the most sense? That way it can 'see' all the cylinders more equally.

This may be one of those deals that unless you're really trying to wring out a lot of hp for a race application, it won't matter a great deal.

I'm interested to see what others have found in real world testing

http://pentastarpower.com

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[Brandnew]

Thanks for the reply.

Planning to run the car in two settings: street and track. Street will run about 5psi; track will run around 12psi. At the highest boost it should be around 2.0-2.1 hp/cu in.

Can you expound the on the balance tube (cross-pipe)?? I've seen them referred to (and even shown) a few times but I haven't seen a lot of detail on them.

FYI: This will be on a 2.8L V6. I already have a twin turbo so I understand the in's and out's; but a single turbo's on V-engines is a new direction I wanted to go.

 

[furious70]

well, just thinking out loud, but I think most single turbo systems applied to street cars just hack a flange onto one of the exhaust manifolds, and then run a cross pipe about the same diameter as the tailpipes used on the car over to the other side along the bottom of the tranny. This would be the worst way to do it IMO, as the turbo won't see the other bank very well at all.

A full on race car will usually put a thumper up front and have piping similar to a twin turbo, just that the 2 banks merge before going into the turbine. I would try to do it this way if possible. Fittment into a street car might be impossible however.

http://pentastarpower.com

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[SMOKEY44211]

Take a peek under the hood of a Buick Grand National. Factory turbo'd V6. May give you some ideas.-----Phil

 

[turbododge]

For the boost and output levels you are looking at, I think the actual design of the manifolds is not going to make a huge difference. For many years tha standard method of doing a single turbo on a V engine was to use the standard exhaust manifolds and use a "crossunder" pipe to connect them between the stock outlets. Usually you would put in an expansion joint in this pipe. You then weld on a tube and turbo flange to either manifold, wherever you want it. The most common location is in the center top of one of the manifolds. Wastegate(s) can go on another weld on location wherever you want. You have to be in a very sophisiticated, high boost and output, situation before you need to start worrying about equal length/diameter etc, as exhaust scavenging does not really exist in this type of situation. For street stuff, I have found that keeping things short and insulated to save heat is, by far, the best optimization you can work on.

 

[hotrodwrx]

You may also want to look at the Subaru WRX / STi for a similar situation. As it is a flat 4 2.0/2.5 Liter engine you have the same feed from 2 wide spaced cylinder banks problem you do with a V-8. The stock engines make 227 - 300 hp, but the big boys are pushing 750+ hp on the drag cars. The cross over pipe in this application goes around the front of the oil pan, and attention needs to be paid to good insulation on that long section of pipe. The handful of folks running after market equal length headers usually loose more low end torque than they gain in top end flow. Don't make the runners too large in dia or your low end performance goes in the dumper. The long runners and large diameter result in slow spool on the turbo. Several of the big players are running lightly ported stock manifolds, with a single turbo at about 20 - 30 psi boost.

Larry

 

[Brandnew]

Thanks for the replies. Looks like I don't have to worry about the collectors too much.

I know Grand Nationals have this set-up but I don't know of anyone locally with one. A search of the internet prior didn't turn up any good EM pictures.