*7M Crank RPM Limit*

Clifton

Clifton

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Apr 5, 2005
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Stock valve springs don't loose seat oe open pressure. I measured mine (180K+ miles) when I was putting in CompCam springs, was using a Rebic LC to increase revs. I checked seat and open pressures. I don't have the specs on hand but they were within 2 lbs from stock pressures. I really doubt you can kick out a shim with the stock cams.

Airflow through the head, or lack of it is what will make revving to 8K worthless. I have yet to see a 7M dyno that made power over 7k with any turbo. Straight 6 cranks do have greater harmonic vibrations. Unless it's a roadrace car held near redline for long periods of time I don't think it would be a problem. 8K would put more strain on the rods though.
 
group a supra

group a supra

SPAWNING AN INTERCEPTOR
May 5, 2005
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learning to weld :) in the united kingdom
well ian inregards to the 6m crank i suppose i'm cheating as mine is a group a one but i will let you know how far to rev her when she runs again
but had use to spin her up to 7.5-8k on the last one which was 6m again group a crank you know spare one in my garage i showed you
so who knows it felt ok to me but my power band wasnt set up for it then so it was a pointless excersise from a certain point of view lol
 
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Fuzz420

Fuzz420

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Apr 30, 2005
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IJ. said:
Funny when mine was NA I can't remember hitting a limiter at all!
(don't even know if NA's have one)
Click to expand...
yea we have one, but how ofter will u see it :dunno:
I hit mine a few weeks ago for the first time in 2nd @ about 6500rpm.I have a 90 ecu and red line is 6200. Ill be honest it seemed like i got the most power just before the rev limit
 
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figgie

Supramania Contributor
Mar 30, 2005
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Clifton said:
Stock valve springs don't loose seat oe open pressure. I measured mine (180K+ miles) when I was putting in CompCam springs, was using a Rebic LC to increase revs. I checked seat and open pressures. I don't have the specs on hand but they were within 2 lbs from stock pressures. I really doubt you can kick out a shim with the stock cams.

Airflow through the head, or lack of it is what will make revving to 8K worthless. I have yet to see a 7M dyno that made power over 7k with any turbo. Straight 6 cranks do have greater harmonic vibrations. Unless it's a roadrace car held near redline for long periods of time I don't think it would be a problem. 8K would put more strain on the rods though.
Click to expand...

harmonics need to be damped. I have the part to do the damping so I have no worry ;)
 
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IJ.

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Mar 30, 2005
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Clifton: It would be good if you can dig up the specs as mine were something like 30 lbs at installed height when it was disassembled.

Steve: You've got me all wrong on this I'm NOT saying a 6M crank can't do it just that a 7M Crank is smoother for me at the same RPM so this should equate to better bearing life over time.

Fuzz: LOL I can't remember ever hitting mine and I wasn't shy about revving it! (What does the stock limiter do?)

Figgie: mmm yes you do! ;)
 
Fuzz420

Fuzz420

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Apr 30, 2005
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IJ. said:
Clifton: It would be good if you can dig up the specs as mine were something like 30 lbs at installed height when it was disassembled.

Steve: You've got me all wrong on this I'm NOT saying a 6M crank can't do it just that a 7M Crank is smoother for me at the same RPM so this should equate to better bearing life over time.

Fuzz: LOL I can't remember ever hitting mine and I wasn't shy about revving it! (What does the stock limiter do?)

Figgie: mmm yes you do! ;)
Click to expand...

Well The car screams like a bat outta hell up top, but the rpms are barely climbing. But when u hit it , the car sputters likes its not gettin fuel.I didnt know what it was at first until i looked at my tach and relized i was pass 6200:naughty:
 
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chevyeater

wastegate hose is pulled
Mar 30, 2005
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Is it making any power Ian?

The mildly cammed 7M I tuned didn't make much past about 7k (began dropping off @ 6500). My car however, with CAMS, likes it up top, when it is in the mood to pull clean.
 
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IJ.

Grumpy Old Man
Mar 30, 2005
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Kurt: The ports are +2>3mm

Brian: .351"/9mm lift 280 degrees duration 226@50thou

I think a lot of my success is the 1.06 AR on the GT3540R it's letting it breathe up top and limiting the hit at mid range making it drivable.
 
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IJ.

Grumpy Old Man
Mar 30, 2005
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It seems to be a really good combination that under full throttle/18 psi is right on the limit of what the tires can cope with but even in the wet I can use up to 14 psi with no loss of traction!

I think anything over 20 psi will easily over power the tires making it hard/dangerous to drive.

Pretty damn happy how it's come out not to mention the 28 mpg cruising! :)
 
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