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I've been looking at turbocharging a 3.0L block using a stock 2.7L head. From what I've learned so far, the 2.7L head is compatible (bolt on) with the 3.0L block and also the 2.5L Turbo hardware. I've been told (understand so far) the 2.7L head requires the Turbo exhaust valves in that configuration, I was only looking for confirmation.
You'd want the turbo exhaust valves there to deal with the heat, but they are the same size/flow potential as the stock 944 2.7 exhaust valves.
If you do go ahead with the build please share it here...the 3.0 stuff is certainly monstrous in power/torque output.
Longer duration makes for the nice lumpy idle in 60's muscle cars. I had a .550 lift and 320 degree duration Crane cam in a 396 Chevy. Longer duration loses you some low end torque, even more with a very free flowing exhaust system (open headers) in return for more higher RPM power. Trick is finding more usable power where you need it, be it high, low or mid-range. The 968 addressed this issue with variable cam timing.
Spencer, thanks for the lesson in valve lift in relation to valve size. I think the intake valves on the 396 were 2.12 inches so your formula is smack dab on for my old Crane cam.
Based on my testing, experience, and the fact that a stock 944 engine has so many other hinderances to airflow - additional lift is the last thing it needs.
I realize you are looking for "free" horsepower, but it just isn't there in this motor.
If you want more power, you are going to have to change components. Air flow meter is the #1 start. Then Muffler. If you want to play with your powerband, you can mess with the cam, but the stock cam has a great street /daily driver profile.
When I first read your thread title, I thought you were going to talk about machining the cam box for a solid lifter conversion. This will allow a more aggressive ramp profile to the cam, which will help airflow.
Remember, peak lift will help high rpm breathing, but, this is a 2 valve head. High rpm and breathing physically aren't possible due to space constraints, when compared to a 4 valve head.
If you are thinking high rpm in relative terms(for example, if you want the engine to make power to 6500) this is possible with just a cam and exhaust change (recommended to replace air flow meter for maximum gains).
Interesting idea's, ......There is Horsepower to be had with this motor
I've had built a short stroke 8 valve 3.0 Engine with the stock AFM, different Cam and a lightweight smaller bore exhaust system which has achieved very good results
- 205 bhp @5799 rpm
- 205 ft lbs @4500rpm
it even has 190 ft lbs @ 2850rpm!
Interesting idea's, ......There is Horsepower to be had with this motor
I've had built a short stroke 8 valve 3.0 Engine with the stock AFM, different Cam and a lightweight smaller bore exhaust system which has achieved very good results
- 205 bhp @5799 rpm
- 205 ft lbs @4500rpm
it even has 190 ft lbs @ 2850rpm!
You'd want the turbo exhaust valves there to deal with the heat, but they are the same size/flow potential as the stock 944 2.7 exhaust valves.
Thanks for the confirmation, that's the plan I was working to. I'm still collecting parts for the build, the 2.7L head was a little hard to find but the fellow I bought it from tossed in the turbo valves with the head. I was pretty happy about that.
Originally Posted by V2Rocket
If you do go ahead with the build please share it here...the 3.0 stuff is certainly monstrous in power/torque output.
I most certainly will. I plan to start a 3.0L build thread once I get going. That's "Phase II" of my S2 restoration and I'm still not sure I'll do it, I need some track time with the mostly stock car before I do anything really exotic. In fact I'm thinking about buying a separate 3L short block and starting from scratch so I can keep the stock S2 engine as a spare, but I've gone ahead and beefed up the power train regardless. It will be ready for a turbo if/when I do it though.
I'm almost finished with "Phase I", which is to build the car to Firehawk specs. Maybe the end of this month I'll have it on the track.
Indeed there is more duration with both the Jon Milledge bumpsticks. You can see the curvature is not as flat towards the toe (point) on his cams & the nose appears more rounded which will keep the valve at maximum lift longer. As I mentioned before, the stage 2+ (my term, JME calls this "3/4 race" also has more lift). As a daily driver the milder cam was far superior to live with.
10-02-2016, 11:17 AM
