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Can I supercharge my 964

I have a fresh built 3.8 motor and would like more power if poss.
It started as a top end re build as follows
New je pistons 10.5:1
Existing motorsport heads, valves and cylinders.
On initial starting the right cam failed destroyed the timing gear and filled the case with debris.
We have totally striped the motor and are replacing all bearings etc.

Can I install a supercharger with this compression ratio?

Old 08-27-2011, 01:33 AM
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well you would have to do a low boost anything pass 7 lbs will not be good. ideal compression i was told is 9.5:1 or less
Old 08-27-2011, 03:21 AM
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10.5:1 is really high for supercharging. It would require a really efficient intercooler, fairly moderate boost pressure, and the most modern fuel injection you can get with lots of safeguards built in. Meth injection would be a must too IMO.

If everything was done above, you'd have a great motor on and off boost I'd imagine.
Old 08-27-2011, 05:56 AM
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Quote:
Originally Posted by 911 wide View Post

Can I install a supercharger with this compression ratio?
No
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Old 08-27-2011, 07:16 AM
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Supercharging or turbocharging with that high a compression ratio is not good. The boost you could add would be so small that it is not worth the time or effort. You stated you weren't happy with the output of a 3.8 at 10.5 compression. If you list what HP goal you are shooting for, there are very good people here that can tell you how to get there.
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Old 08-27-2011, 09:15 AM
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Thanks for all of your advice.
It seems that the general opinion is that the compression ratio is to high.
The motor is a 964 built to carrera cup spec, I think.

Mahle cylinders 102mm
Je 10.5:1 pistons
Heads and cylinders have a 4.5mm sealing ring
Valves are motorsport 49.5 inlet 51.5 exhaust
That is about all I know
What else can I do to improve power?
John
Old 08-27-2011, 01:13 PM
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Your stuck at around the 300-320is hp without spending major $$$. Remember, these aren't SBC motors and Porsche didn't leave a hole lot on the table which is why they cost so much. The usual exhaust/chip enhancements are about the biggest bang for your buck that you'll get. Anything beyond that and the cost per hp is significantly higher. Trust me, I went over this in my head a million times and decided I would keep my 3.2 and turbo it.
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Old 08-27-2011, 01:29 PM
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Quote:
Originally Posted by 911 wide View Post
I have a fresh built 3.8 motor and would like more power if poss.
It started as a top end re build as follows
New je pistons 10.5:1
Existing motorsport heads, valves and cylinders.
On initial starting the right cam failed destroyed the timing gear and filled the case with debris.
We have totally striped the motor and are replacing all bearings etc.

Can I install a supercharger with this compression ratio?
Yes you can, albeit a low boost 0.45 bar setup. Contact Protomotive. They are the experts on these aftermarket systems.

BTW, too much parasitic losses with superchargers. They rob engine power to make power. Turbo'ing is far more efficient

Old 08-28-2011, 03:24 AM
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