Wondering on a turbo or twin turbo build how big of gain you see with headers compared to manifolds. I know there are many guys out there making huge power with manifolds and they would work well do to the fact the hug the block but i dont want any restrictions at 1000+HP or something that will be short lived!

 

The turbine housing is the choke point in most cases.
Manifolds will do the job with room to spare.

 

Well thats good to know! Anyone know what the best flowing manifolds are and what the port sizes are?

 

Use whatever fits your chassis. The C6 manifolds "look" the most restrictive and I used them on a 1000rwhp car.

 

How about LS7 heads what ones work? I was looking at the cast Hookers and they say LS7's excluded!

 

LS7s have a different port location and style, the C6 Z06 manifolds would be the only factory ones to fit.

 

I did a search and found that the LS7 ports are in the same location just D shaped and a bit larger . Anyone use any other type manifold on LS7 heads besides C6's?

 

Another added bonus of manifolds... There ability to hold more heat in which leads to faster spooling.

 

Yes that is a added bonus now if i can find some mani's like the truck style to fit the ls7 heads!

 

Any reasonable design can be made to work and achieve 1000hp. No question. But there is a lot of misinformation about this on the net.

Fact: Tests on Honda's found 10% power gains over the best logs by going to proper headers and merge collectors. i.e. the best headers always beat the best logs/manifolds/shortys.

The key is good flow, so turning a header system too tight under a hood can sometimes be counter productive if the headers end up as restrictive as a decent manifold. Think CFM. Yes you need velocity too, but not at the expense of excess backpressure.

CFM = Gas flow which turns the turbine - not heat. Aim a gas torch to your turbine and see if it starts spinning faster! The biggest gains from tight and hot and short is for the fabricator who has less to do and it is easier and cheaper.

Yes there is some energy in heat but the difference is not great and anyone that has experienced a well set up rear mount turbo knows this for a fact. They are typically 400 degrees cooler yet power some of the quickest turbo cars on the planet.

Now for the final myth to bust - just because the turbine is the most restrictive part of the exhaust system does not mean adding more restrictions has no impact on power. If everything else is capable of flowing maximum cfm for the power level required with the least backpressure and pressure drop then the turbine acts like a vortex much like a collector that steps down (except it uses the increased speed of that vortex/restriction to spin a turbine). Adding more restrictions hurts not helps.

But again - if the aim is 1000hp - anything will work. It is just a really good header with merge collector will make more and have less back pressure, therefore less pressure drop assuming equal attention to the intake side.

The difference in power is far greater and of more use than any quicker spool time from the shorter hotter setup. Does not make manifolds wrong, I just don't like to see myths repeated when back to back dyno results have been clear. Good headers win.

 

Truck manifolds have been 200mph in the 1/4 no need to get technical as above, if it ain't broke don't fix it myth or not...

 

um............ false.

ALL LS ports are in same location. a LS2,3 manifold will work on a LS7 and vs versa. just like some one said the LS7 has a D port.

 

So as long as they are D port and not round port they will work on ls7 heads?

 

no. example. APS was cheap. they used the same manifolds on the C5 vettes and the LS7 z06 vettes.

it is round on the manifold. it doesnt need to be round. you just need to make sure the exhuast manifold is begger then the exhuast port on your head. so nothing inner fears with the flow

 

The holes are in the same location but the ports ar slighty raised.

you have 3 basic configurations-

Stock LS1/2/6
LS3/L92 port is raised .060
LS7 is raised .125.

You should have no issue, just check the port match, and it may take some grinding.

 

Thats what I was trying to say, I couldn't think of raised though.

 

That approach works but it does not answer the posters question.

The question was how much power is gained by proper headers vs manifolds/logs etc.

The answer is up to 10% gain is possible.