944 S head prepared for 2.5liter turbo engine
12-02-2008, 06:21 AM
#17
Rennlist Member
The head is aesthetically very nice. Did you flow test it before and after?
12-02-2008, 09:02 AM
#18
Three Wheelin'
Thread Starter
No, I did not, because we didn't make any significant changes that affect flow. I guess that power/torque numbers will tell how good this head is after we have been on the dyno and/or some top speed challenge 
I plan to dyno the car on 0.7 bar also to see what stock 951 would approximately produce with 16V head. Of course, turbos are different etc but it gives some food for thought I hope.
I plan to dyno the car on 0.7 bar also to see what stock 951 would approximately produce with 16V head. Of course, turbos are different etc but it gives some food for thought I hope.
12-03-2008, 01:00 AM
#22
Drifting
It's been a while and the progress is kinda slow on my project car, but here's a little update.
Finally received the 944 S 2.5liter head, new stainless steel valves, full radius cut (not 3 angle etc) and machined seats, new guides, new stems. Exaust ports ceramic coated and intake ports and valve seats got small improvement in flow.
Photos are taken with a cell phone, so some are semi-decent quality, some are crappy quality
Head just before installing the valves:
Combustion chamber:
Generously flowing intake port, these are HUGE on Porsche 16V heads:
Ceramic coated exaust port:
And here's the head with valves installed:
This is the turbocharger for this engine, meet Holset HX40:
Finally received the 944 S 2.5liter head, new stainless steel valves, full radius cut (not 3 angle etc) and machined seats, new guides, new stems. Exaust ports ceramic coated and intake ports and valve seats got small improvement in flow.
Photos are taken with a cell phone, so some are semi-decent quality, some are crappy quality
Head just before installing the valves:
Combustion chamber:
Generously flowing intake port, these are HUGE on Porsche 16V heads:
Ceramic coated exaust port:
And here's the head with valves installed:
This is the turbocharger for this engine, meet Holset HX40:
12-03-2008, 02:12 AM
#23
Looks good. Which head gasket are you using and do the stock tq-settings on bolts still apply?
Do you plan to use the stock chain tensioner or do you have custom intake cam and run it off the belt?
1bar seems a good 'limit' so "don't blow it - literally.
Do you plan to use the stock chain tensioner or do you have custom intake cam and run it off the belt?
1bar seems a good 'limit' so "don't blow it - literally.
12-03-2008, 03:16 AM
#24
Three Wheelin'
Thread Starter
I'm not going to make to some high-revving monster, redline will be around 7000. This turbo will get positive pressure with this engine around 2500 and by 3500-4000, I expect full boost. So 3500-4000rpm of full boost is enough.
All 944S head torque settings apply, what should cause otherwise?
My grand plan is to use two exaust cams as I don't like multiple weak links. With two cam sprockets, there's only one, the belt itself. And this way I can dial the best cam timing/overlap for my needs also.
All 944S head torque settings apply, what should cause otherwise?
My grand plan is to use two exaust cams as I don't like multiple weak links. With two cam sprockets, there's only one, the belt itself. And this way I can dial the best cam timing/overlap for my needs also.
12-03-2008, 07:16 AM
#26
Drifting
Join Date: May 2006
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well I bet your new manifold blows the drawback is exhaust cams are smaller I'm thinking about pushing the valves up 20 to 60 tho so you have some base rad to regrind a bit more from them and to lower my compression a little as well you cant go to far because it eats port flow as the bend starts to shorten
12-03-2008, 09:25 AM
#27
Three Wheelin'
Thread Starter
Exaust cam has exactly the same profile as intake cam, I compared them side by side.
I think stock cams are sufficient for the goals I'm aiming, remember, Markus had 495rwhp 1.3bars on his turbocharged 968 engine with stock cams. True, 968 cams are a bit different but nothing major.
And just for information. My machinist told that stock 944 S valve pockets have enough meat to go bigger valve sizes. Safe maximum is +1mm on each valve.
I think stock cams are sufficient for the goals I'm aiming, remember, Markus had 495rwhp 1.3bars on his turbocharged 968 engine with stock cams. True, 968 cams are a bit different but nothing major.
And just for information. My machinist told that stock 944 S valve pockets have enough meat to go bigger valve sizes. Safe maximum is +1mm on each valve.
12-04-2008, 04:36 AM
#30
Formula One Spin Doctor
Rennlist Member
Rennlist Member
Got dat ting running yet ?
