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What rev limit for 2.7 rebuild
I have just done a rebuild of my 75 2.7.We put in new RS Mahle P&C's,with an E-Grind cam port and polished heads ,new valves ect..The motor is fully broke in now and pulls hard right to its pervious rev limit of 6300.Should this motor rev to the E specs of 7000 or so or should I just keep the current rev limiter in it.
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Brent Lineker 1975 911S weber conversion. |
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02-28-2009, 01:10 PM
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Join Date: May 2003
Posts: 3,346
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The limiting factor is the valve train. There might be different seat pressures for the valve springs but if it was built with the specs for a 2.7 RS or 2.4 E or S engine then you can safely rev it to the 7000 limit for the 2.4 E. Check with your head rebuilder to see what spec. he set the spring heights to.
-Andy
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72 Carrera RS replica, Spec 911 racer |
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02-28-2009, 07:11 PM
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Join Date: Dec 2001
Posts: 9,569
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6800, same as the stock E. You can rev higher but the engine just makes noise, not power, until the expensive noise at around 7500.
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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03-01-2009, 05:30 AM
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Max Sluiter
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But if you are racing, you can rev beyond the peak power, provided it does not fall off too steeply, and then when you change to the next taller gear the RPM drop will put you right back in the powerband.
It mainly depends on the shape of your powerband- how flat is it before or after the RPM in question. This is for racing, though, not time between motor refreshs. 
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1971 911S, 2.7RS spec MFI engine, suspension mods, lightened Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance |
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03-01-2009, 10:58 AM
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1971 Porsche 911S
