Contour Enthusiasts Group Archives Forums Modifications Duratec Performance P&P heads

Ronan a 15hp increase is a good increase on these cars short of FI or a 3.0 swap. Did you cut in 3.0 valves or stay with stock. I have a knack for overdoing things. I am just wondering if the valves and porting would be to much for a 2.5.

P&P is definitely something you don't want to do over-do on your n/a motor. as for the NO2, try N2o, it might work a little better... Also, if you are considering a turbo....please don't consider a high compression route....that's kind of a bad thing to add a turbo to....are you sure you're up for tinkering around with this stuff?

3L exhaust valves are 30mm and the 2.5L exhaust valves are 26mm.
The intakes are 35mm and 32mm on 3L and 2.5L respectively.

I played with my dyno simulation program many times on this and I also have practical experience on these motors both 2.5 and 3.0.
If you stay 2.5L my opinion would be to have new 30mm exhaust valves cut into the heads but stay with the 32mm intakes with heavy porting. This may cost you a tad torque below 3500 rpm, but it will give you the breathing capability you will need about 5500-6000 rpm where you will end up making your 200 fwHP. Then when you decide to put those heads on a 3L it will perform just as well as any 3L with 3.0 valves. I have already ran the simulations for the 3L with 32mm intakes and 30mm exhaust versus 35mm intakes and 30mm exhausts and it makes little difference in overall power. In fact the torque remains higher in the midrange with the 32mm intake valves on a 3L. This is all based upon indirect assumptions from many engine projects and the computer simulations, but it is a good enough assumption that I would use it if I were doing a two stage project later on. That includes 2.5L N/A -> 2.5L turbo or 2.5L N/A -> 3.0L N/A.
It would still work fine if you went three steps from 2.5L N/A -> 3.0L N/A -> 3.0L turbo.

war......

Well I didn't explain my self very well. If I put in a 3.0 it will be of the high compression variety with the exrta power via a bottle. If I can raise the cash for a turbo it will be a 2.5. Which ever route I go I think that the headwork would be a benefit. What my main question is what are the pros and cons of a P&P, deshrouding, and 3.0 valves on a NA 2.5 SVT. The reason I ask is my car is put away for the winter. I have plenty of mods on the self for this winter. I have plenty of down time and cash for the headwork, but anything else is going to have to wait for a while. Will I see any worthy benefit from the headwork or should I save the 1500.00 for something else

Thanks War, I was hoping that you would pop up soon. I knew what I was planning was an ok start. Just wanted to hear a positive second opinion before I dropped the cash. Well sorta I pulled the heads last night. Had to clean the Uppers and Lowers anyway. Thanks Rob

Hey Rob, just to answer your question, I used the standard 2.5L valves on my head job, and got those figures I posted. I do have pics of the heads after the work if you want them to have an idea of what was taken off etc.
Mostly the guy just de-shrouded the edges, and smoothed the surface. They looked so good, I wanted to frame them. But then that wouldnt give me much whp

Ronan thanks for the response. I'm going to take it a little further. 3.0 exh valves, 2.5 int, deshrouding and some P&P on the passages. We'll see what happens. I'm sourcing some of the better design 2.5 pistons also. Should be fun.........

Best of luck with it Rob, I am sure you will at least get the gain that I got, and hopefully more for your efforts.

I think because I was running with headers, no cat, and twin pipes (only 2.5" diameter, restrictive?) it may have helped a bit with the breathing too.

Looking forward to seeing the results when you get it done!

We can run any valve combiniation you want. If we only need to cut in two valves per chamber versus all 4 I can lower the price some. BTW check the GB pricing, best I have be able to do since starting this.