This decision I have to make about what route to take with a manifold is killing me!
The price difference is negligible.

First up:

1)Stock Exhaust manifold - ported and ceramic coated

Positives: Stock reliability (from cracking)
Negatives: Not much of a power gain as DC

2)DC Sports Manifold

Positives: Power gain (but how much? Turbo mag showed 11whp at 1psi less boost!)
Negatives: Possibility of it cracking, especially since I plan to run aftermarket 02


Basically, I can get the stock one, not worry about anything cracking (especially when using aftermarket 02 such as Helix). Or I can get the DC which will most likely make more power for around the same price but Id have to have the possibilty of it cracking.... I need some GOOD opionions here!

 

there was a big thread on this last week.. but my opion is go with the tube header, my prefence, dnp, and get it coated... cause stainless is a b1tch to keep clean... i ran dnp for 2 years no probs.. with the header i had, big o2, and 3 inch pipe i could hit 22 psi at 3100 rpm, from a rolling idle..

 

Anyone that buys a header I have an offer for you. Bring the car to our shop with the stock manifold, we will dyno it. Then install the header and dyno again for free.

I want to find a header that works, if we do we will sell it. As of now, I have seen nothing but losses.

David Buschur
www.buschurracing.com

 

BTW, the dyno runs are free, not the install of the header.

David Buschur
www.buschurracing.com

 

Personally, I havent seen any dynos of ANY headers what-so ever, other than the DC one... however I would definitely get it ceramic coated like the stock one. Dafarmer, what 02 did you have?

David, is it possible to send you a stock EVO manifold and you JUST port it, no jet coat?

 

That's a nice gain for just swapping out the manifold. I'll go with the tubular for sure....isn't it possible to prevent it from cracking under the weight of the turbo by welding it with more bracings?

 

For me I would get the stock ported and ceramic coated. I feel that DC or any aftermarket manifold, all you'll save is a little weight. Also if you get pulled over, having the stock ceramic coated is more believable to the cops that it's stock. But if you have something shiny, then they know that it's not smog legal.

 

Thats not an issue around here. Thats a Cali thing from what I know. We dont have to deal with that BS here in NJ.

 

bump for some more answers, i am in the same boat as you Soon2BEVO

 

+1

 

Here is something else to consider:

(I'm not saying any of this to throw a wrench into anyones plans, just providing food for thought)

In an exhaust system on a turbocharged application (including the Evo), there is a certain amount of backpressure inside the exhaust manifold before the turbocharger. (TIP - Turbine Inlet Pressure)

An ideal scenario would be to have this backpressure equal exactly the amount of pressure that the intake manifold sees. (same as boost pressure measured from the intake manifold) (which is a pain in the butt to achieve as often as people change their boost pressure)

This scenario provides for the most ideal spool and intake/exhaust flow conditions to allow for the most power.

A larger volume within the capacity of an exhaust manifold can decrease the amount of TIP too much and create a loss of power. Too much TIP within the exhaust manifold can also limit power.

Weight each of your options carefully and find a system that will provide the closest amount of TIP to that of the amount of boost pressure you intend to run, if that information is available (which it may not be).

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A separate yet equally important point:

On a naturally aspirated vehicle, there needs to be a specific amount of backpressure within the entire exhaust system to maintain the highest level of torque as well as horsepower. Using an exhaust system that is too open can result in higher horsepower, but at the sacrifice of some torque.

This is not the case on a turbocharged application, however, where there is no reason to have backpressure in the exhaust after the turbo. Having too open of an exhaust will create additional noise and possibly fitment issues, which need to be considered for the areas that you live and drive in, but on any turbocharged application, the highest flowing exhaust possible is ideal. (after the turbo)

 

Thanks for the info!

Well I decided for now Im going to go with the DC manifold. It looks like much better quality to me than the Megan, SS, Pro-1, Maxford, etc. Those all look EXACTLY alike and I have hard of them breaking and Ive yet to see a dyno on them. However, since the DC has a warranty against cracking, priced well, AND has an independent dyno of it via Turbo Mag, I chose it. Im going to have it HPC coated as well!

Tom

 

David, why not cordinate with Ron and have him build and test a header to sell? I'll commit to the first purchase if you can make some hp and/or torque w/o loss of boost pressure.

Dave

 

I personally dynoed the GT Spec header and it made pretty nice power for just a manifold with no tune.



Ben

 

Actually, that's a very common misconception. In reality, backpressure never created anything but pumping losses.

The primary reason why one too large of an exhaust system in a N/A app reduces efficiency is because exhaust gas velocity is reduced to a point that it takes a toll on the inertia effect that helps to draw the intake charge into the cylinder. On the other hand, where backpressure is concerned, if you're seeing something like 2psi or greater in a N/A exhaust system, you're losing power. It's a tradeoff, and the best compromise comes with competent planning.

A turbo system is a bit different, as exhaust tuning is most significant between the exhaust port and the turbine inlet. As you mentioned, this directly affects the pressure ratio between the intake and exhaust. As always, you give up something to gain something else.

A tubular manifold, with equal length runners tuned for best efficiency in the same rpm range as the intake runners, with a very efficient collector, will outperform anything else. The variability of aftermarket manifolds makes this somewhat of a crapshoot. Furthermore, things like the size of your turbo, the tuning of your cams, etc., all weigh into the equation heavily enough to make individual experiences subject to variability.