For S's and Giggles - Any way to raise 993 rev range?
10-30-2010, 03:57 PM
#16
Rennlist Member
What's the realistic life expectancy of the ultra-modified large bore/stroke air cooleds? Quite happy with my meager ~315HP 3.8L that stays within the factory rev range. When I want to go rev happy, the 10.5K of the Hayabusa in the Radical is satisfactory.
10-30-2010, 04:24 PM
#17
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Stock heads, intake and exhaust systems pretty much restrict HP to about 7K. RS cams simply bolster the existing RPM range,... 
. $25K is acccurte.
With an ITB or slide-valve system, the right cams, better heads, lighter pistons, all the above mods (plus the oiling mods), and an appropriate exhaust setup, you're good to 8200+. All that takes is a bunch of $$$$$,.... I know of one 3.9 litre race engine making 460BHP+, but that was quite expensive to do.
. $25K is acccurte. With an ITB or slide-valve system, the right cams, better heads, lighter pistons, all the above mods (plus the oiling mods), and an appropriate exhaust setup, you're good to 8200+. All that takes is a bunch of $$$$$,....
I know of one 3.9 litre race engine making 460BHP+, but that was quite expensive to do.So, hardware, we are looking at:
Rods/bearings - $1500
Pistons and cylinders - JE and Nickies - $4000
reworked heads with RS valves and high RPM springs, retainers, etc.- ??? $4000 (guess - please correct)
Improved Oiling - No idea what you would do here - would you need to crack the block?
Bob
10-30-2010, 04:40 PM
#18
Rennlist Member
Look, Kim spent $30K+ with Steve in '03 to take the stock tired ~120K '95 engine into what it is now. Along the way, it dumped a crank, so a 964 one went in later. This is a 7K RPM engine, at best.
I have no idea how serious you take autocross. For the kind of money that's being discussed to properly and comprehensively take these engines into the 99.9th percentile, a 911 is one of the last places I'd look for ultimate speed.
11-01-2010, 11:15 AM
#20
Racer
Thread Starter
yeah I would rather have a fully built 993 motor than retro fitting the GT3 water pumper. I agree with bob, another 1k rpm would be great in atuox and on the track.. I'll probably end up going the re-geared tranny route to improve accelaration but, would love to have the combo.
11-01-2010, 12:22 PM
#21
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yeah I would rather have a fully built 993 motor than retro fitting the GT3 water pumper. I agree with bob, another 1k rpm would be great in atuox and on the track.. I'll probably end up going the re-geared tranny route to improve accelaration but, would love to have the combo.
11-01-2010, 12:33 PM
#22
Racer
Thread Starter
Bob - I know you did, which is awesome. for some reason I want to stay naturally aspirated, I dont feel like at my skill level I need much more power (probably dont need any) the rev question was just because I love a high revving NA motor.
I think if I ever go with a regear it will help with autox and on the track it shouldnt hurt either!
I think if I ever go with a regear it will help with autox and on the track it shouldnt hurt either!
11-01-2010, 01:10 PM
#23
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Bob - I know you did, which is awesome. for some reason I want to stay naturally aspirated, I dont feel like at my skill level I need much more power (probably dont need any) the rev question was just because I love a high revving NA motor.
I think if I ever go with a regear it will help with autox and on the track it shouldnt hurt either!
I think if I ever go with a regear it will help with autox and on the track it shouldnt hurt either!
Bob
11-01-2010, 01:43 PM
#24
Rennlist Member
11-01-2010, 05:47 PM
#25
compare that to the /30 Cup, /32 RS/CS or /31 RS street
The 2 I like the best are the /30 Cup and the regear that Chris Cervelli did for Leland
the /31 and /32 are going to be better for the guys that also use them on the street, though I think mine /30 is fine there too, the others have the higher 6 for fuel
economy cruise
11-01-2010, 06:34 PM
#26
Nordschleife Master
That just shows how little differences in ratios can make a big difference on track. Zonker actually uses the same 4th and 5th gear that the factory recommends as the optimum stack for Laguna Seca, but 3rd is shorter and 6th is taller. Porsche suggests the following:
1st 3.154
2nd 2.000
3rd 1.571
4th 1.307
5th 1.094
6th 0.941
1st 3.154
2nd 2.000
3rd 1.571
4th 1.307
5th 1.094
6th 0.941
11-01-2010, 06:43 PM
#27
11-01-2010, 07:03 PM
#28
Rennlist Member
That just shows how little differences in ratios can make a big difference on track. Zonker actually uses the same 4th and 5th gear that the factory recommends as the optimum stack for Laguna Seca, but 3rd is shorter and 6th is taller. Porsche suggests the following:
1st 3.154
2nd 2.000
3rd 1.571
4th 1.307
5th 1.094
6th 0.941
1st 3.154
2nd 2.000
3rd 1.571
4th 1.307
5th 1.094
6th 0.941
11-01-2010, 07:08 PM
#29
Rennlist Member
And I just noticed on the chart that the universal tire OD is 24.6". I've been generally running a 275/35-18 or 275/40-17 RA1 during my ownership. Subtle difference.
11-01-2010, 07:20 PM
#30
Nordschleife Master
The other thing is the original topic of this thread, the redline. I posted GT3 suggested ratios, which obviously has a higher redline than all but the most crazy 993 based air cooled motors. So those ratios will come up too short for the 993. I'm just guessing without charting it, but something like a 0.866 6th gear is probably better for a 993 car, as would be a 1.895 2nd and maybe a 1.521 3rd. Basically something closer to the Chris Cervelli ratios that Bill said he likes...