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Okay, moving the efficiency island by having less "backpressure" on the turbo outlet makes sense to me. But if at the same boost before and after I'd expect the car with the ported inlets to have more heat - the turbo is spinning faster to create the same boost gauge reading as it's moving more air right? Certainly higher power too I'd expect. Still a little confused I guess!
Personally I'd lean towards CNC porting. Setup correctly it should mirror a known port job and be easier to do. I'm a fan of repeatability I guess...
Just did mine here. Was in a time constraint so not quite as perfect as I'd do for a customer but came out pretty well. I can tell you that overall the stock heads are designed well and the runners are very consistent. You can really open them up though with porting. Hopefully this will help me hit my 900whp goal with my tiny little turbos. We will see.
Looking good!
Do you flow test also? Any idea how much you picked up with this porting?
Nice EGR blockoff Do oyu use a little gasket maker to seal the EGR blockoff?
Looking good!
Do you flow test also? Any idea how much you picked up with this porting?
Nice EGR blockoff Do oyu use a little gasket maker to seal the EGR blockoff?
I do not have a flow bench. I'd guess I pickup up 15-20% though for sure. I'm guessing on my car I'll pick up 50whp over stock heads.
the block off just has the stock gasket underneath it
Flow work is the same as dyno testing. Trying to compare the results without understanding how the tests were performed just brings in alot of misdirect.
From some results I have, the flow numbers for a stock 996 Turbo head show a raw flow number of 239 CFM (Intake @ 0.400"/25") before any test leakage was subtracted. It also shows it was done with only an inlet bell on the Intake port. The Intake and Exhaust flow numbers seem to mirror one another fairly close as well.
But flow numbers mean nothing if the total inlet system is not factored in. If the Intake manifold and Tbody increase the restrictions what good are head numbers. It can compare head to head, but the whole system has to be tested to see if the work on any head is worth while. The results I have show the same approx flow numbers @ 0.400" through the complete Intake system up to and including the Tbody with ported Intake.
In my case it was worth while as I have the same flow numbers now with the whole Intake system flowed.
The same test done with an Inlet bell, matched lower manifolds on ported heads @ 0.400" lift/25" show numbers in the 255 CFM. What is very clear and easy to see is the head flow becomes choked due to the valve size. From the head work I had done, I have not seen flow numbers in the 280 CFM region. Max flow numbers on my ported heads was in the mid 260's x 25" but at the higher lifts.
let me ask this then. is it worth the cost to increase the size of the t/b and y pipe and plenum if your not porting or polishing the heads? ie: its much easier to do this during the mod process unlike taking the motor apart to do the heads
01-10-2017, 09:21 AM
Do oyu use a little gasket maker to seal the EGR blockoff?
