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Pat RUFBTR Pat RUFBTR is offline
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Join Date: Aug 2014
Location: France (Paris)
Posts: 354
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Quote:
Originally Posted by kenikh View Post
I just had a long conversation with John Dougherty about 993SS cams in a 3.4L 930. Per his recommendation, 993SS are generally not recommended for turbo engines under 9.0:1 (no typo) static CR at book cam timing. He said that if you advance the cams 4 degrees, 8.5:1 will work. Although he's never tried it, he expects that it might be a little laggy, especially if you're running a slower spooling turbo.

Once you're on boost, it all changes, of course.

Based on my calcs, at-idle static CR (on book timed) 993SS cams is even lower than for GT2 cams, meaning you can expect lazy performance off idle. Advancing the timing will net you a little more dynamic compression at idle, but you still shouldn't expect anything better than somewhere between 964 and GT2 performance off the line.

The OP stated he wants more off the line grunt at the expense of top end power. 993SS cams are not the solution for his problem. From his initial post, it sounds like he is running DC15 cams, which although nice, will give up a little off idle grunt compared to an SC cam.

In reality, the OP is probably best off emailing with John Dougherty to get a custom ground cam - ideally something with near stock overlap to maximize off-idle compression, with a little more lift dialed in to allow a little more top end power than the stock cams. A DC 10/12/13 may be a good option in this pursuit.

FWIW, my CIS 8.5:1 CR, 3.4L motor is now coming together with 993SS cams, K27-7006, 40I/38E ports, knock control and twin plugs. Knock control means I'll be able to run a sharper advance curve which should mitigate some of the off idle laziness. Cams will be timed w/ 4 degrees of advance. I'd of course be best served with fast spooling ball bearing turbo, but budget isn't accommodating right now. I'll let you guys know what they are like once I do.
Hello,
It is strange, in a conversation with my friend, Dougherty told him that of the good about acc 993ss. Compared with those of Gt2/ Gt2evo they are better in the bottom and at the middle regime and then our power is not situated in 7500tr / mn.
I would be very curious to have more precision about acc Edelweiss Motorsport, I found nothing on their Web site.
Old 10-10-2014, 12:09 AM
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