Inliners International Forums General Discussion Hi Performance Turbo exhasut manifold

if i was to turbo my 250, would it increase performance significantly to use headers vs the stock exhaust manifold?

You would have to use custom made headers. The headers sold by clifford for example are long tube headers and what you want are short headers. You want to keep the exhaust gasses as hot and quick moving as possible to stir up the turbine. Long tube headers slow down the gasses and lower their temperature. So if you are going to turbocharge the inline six either go with short custom headers or go with the stock exhaust manifold. If it's a street car with less than 10 psi of boost then the stock manifold works fine.

Clifford also has shortie headers But they to would not work as well as a set made Just for the turbo. Because all after market headers are split 3&3 you want all 6 into one Then tied to the turbo.
Like Tatao said the stock will work good for less then 10 psi. And it would be good to either make them from Stain. steel And have them ceramic coated inside and Out They will last Much Longer that way. Hope this helps }[oooooo]

I've thought about doing this before (and still want to, so I'm paying attention). It would depend what kinda of fabrication talent you have and wether you have access to the right stuff. It would be better to use a header type manifold for the exhaust, but you have to ask yourself if the time and money wouldn't be better spent elsewhere. If you are set up to make a manifold go for it. To have built though........I have a feeling it would get prohibitively pricey pretty quick.

What kind of induction are you using with your turbo? Draw through carb, blow-through carb, throttle body injection, port injection? And for boost controls? or are you even using boost controls? Intercooling/aftercooling? Size of turbo? I've done a bit of research and I kinda wanna know what you're planning.

Here's a good site for ideas:
http://www.megasquirt.info/

go to the page on turbocharging your megasquirt, the ideas apply to any engine.

more to come when I have a few more minutes.....

Unfortunatley,cast iron manifolds may not offer as good of flow as tube headers,but the fact is that they retain heat better, which actually makes them better for turbo use.Another problem with tube headers( they get red hot with a turbo)is they do not support the weight of the turbo as well, so they are prone to bend, leak and crack. Having a good flowing exhaust system after the exhaust leaves the turbo is more benifical.Paul

Having read responses I have to say,
yeah but.....
If the stock manifold is as bad as it's made out to be why use it for any application, turbo or not?
How about the cast iron headers Tom Langdon sells?
http://www.stoveboltengineco.com/acartpro/product.asp?productid=89
or
You can buy flanges and make a set of headers?
or
There's those old (63?) 292 manifolds, but they must be hard to find. I've never even seen one except in pictures.
I have a truck manifold with a larger outlet, 21/2" I beleive, that I thought I'd use if I ever try a turbo but frankly it's no beauty either.

I vote for the stock manifold for milkd boost applications. You can have the manifold extrude honed can't you. It's durable, cheap, easy to find, and hardly any fabrication required for a turbo to work with it. Seems logical to me. Good luck. John.

thanks for the advise. due to the ease of install and cost im gonna go with the stock manifold. i mean its only for street use so i wont ever exceed 15lbs boost anyway.

I'm going to vote for the stock manifold after thinking about it. You wanna keep the projects small after all. Get that turbo the easiest way first, stock manifold. Get used to the turbo, and so on. and maybe later upgrade. But yeah, stock sounds good to me.

i'm doing the same project right now and am going to use a truck 3 bolt 2.5 manifold. the other issues such as boost ,timing and fuel are much more important. give me a shout i've got alot done with mine, with planning and parts. tom

i was thinking of using a truck manifold as well, but the last time i tried to use a 292 manifold with my offenhauser intake, i couldnt get them to mate up properly and i ended up grinding through the exhaust manifold and even after that they still didnt mesh together. what intake are you using?

Originally posted by tlowe:
[QB] i'm doing the same project right now and am going to use a truck 3 bolt 2.5 manifold. the other issues such as boost ,timing and fuel are much more important. give me a shout i've got alot done with mine, with planning and parts. tom [/QB

That's the same manifold I have, I think.
You want to use that because it seems like it would work well bolting up to a turbo?
I'm not sure about it being a good piece as far as flow charactoristics but I'd probably end up using it vs having something made.

i'm using a clifford intake. i had to modify the bottum of the intake to clear the exhaust manifold. i also bolted in a home made plate to cover the heat exchange hole on the exhaust man. tom

Has any one considered sending off stock exhaust manifold to Extrude Hone? They pump an abrasive media through the manifold and it polishes the inside. Then maybe get it coated.

I looked that up and it sounds like it would be a great thing to have done. That being said it isn't cheap. I haven't heard of it being done here but maybe someone has.

Is the 2 1/2 sized manifold any better flow wise then the stock 250 type? I am asuming that to use the stock manifold for a turbo you would have to cut off the lower half and weld on the turbo mount.

The 2-1/2" truck manifold is a good start but kinda thin and will eventually crack in a million places. There is a cast iron turbo manifold available from Innovative Turbo in Simi Valley, CA. Try www.innovativeturbo.com, ask for Justin. I have one, it is bullet proof. good luck.

Inliner #3795 that is really interesting. What did this manifold go for? pics? The turbo manifold looks to be the hardest part of a turbo conversion.

i looked at their web site and did not see a manifold for a chevy inline six. 3795, is that what your working with? tom

making a turbo manifold isn't hard(if you're handy with a welder.)my son-in-law has a holden "red" six(like a scaled down version of the chev 292)and he got an old set of headers from a swap meet,cut the pipes off around 4"-5" from the head(give enough to clear the inlet manifold)and then welded a 3"X3" steel box tube (3mm thick) section on to them.cut the hole for the turbo and then welded another 3mm plate over the hole(cut ot of course)to give some more meat to drill and tap stud holes(3/8") to bolt down the turbo.made the entire manifold in a few hours, with a total cost of less than $60.still on the motor and still making 15lb's of boost!

sounds cool and cheap buickroadster.
i talked with innovative, they do have an inline chevy six manifold. they sent me a picture. i'd post it but don't know how. the turbo is mounted dirrectly below the carb. priced at 595.00. they are also going to send me a engineering drawing of it. i want to see if it will fit my chassis. tom

Think you could send me the stuff you get tlowe? I know how to post pics and I'm in engineering so the drawings will be useful to me. It may be a touch expensive for me, but it is a pretty cool idea and I'd like to know more.

Pic of the turbo manifold available from Innovative.

It looks solid and well done just from the pic. I'm not sure I like the location of the wastegate. I think that's it to the rear of the manifold (so unless I'm mistaken). Corky Bell's book indicated a good wastegate should be able to vent pressure from all the cylinders and this one wouldn't be able to. So I'm not sure.

I think this manifold would work fine & it is not too involved to fabricate a down pipe for it. I think a lot of us should buys these & teach those V-8 thingys some lessons :-)
tlowe .... got any updated pictures of your progress???