Anyone bump their rev limiter up?
02-17-2008, 11:22 PM
#1
Safety Car
Thread Starter
Anyone bump their rev limiter up?
Car was at the tuners for an update with meth. Never got the meth running because it kept bursting the cheap plastic hoses. Ordering the stainless steel tomorrow. Anyway, I sent the head unit to Procharger for refurbishing and had it re installed. Car is making 8 lbs of boost and is at 551 rwhp now without the meth. Tuner says there is plenty left, almost to the point of questioning whether or not the heads are stock(?), but that is another thread. Anyway, the power is still climbing at 6400 rpms and I have heard these engines were ok at 7000 rpms if the power was there. Just curious if anyone has bumped theirs up? If it is there, why not use it. Thoughts?
02-18-2008, 10:08 AM
#2
Melting Slicks
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I have bumped the limiter up, but I have a built motor. If your heads are stock than no, I wouldn't touch the limiter. The biggest concern I would think would be the valvetrain. If/when you completely upgrade the valvetrain, then I would say you could look into raising it, although at your power level, if you starting revving higher and making more power, I would think your bottom end would be on borrowed time. Hope this helps 
02-18-2008, 10:21 AM
#4
Safety Car
Thread Starter
I guess it would be best to leave it like it is. This power thing makes you greedy. 528 rwhp has been enough for me, but now I am thinking 600
. I must not be greedy, I must not be greedy, I must not be greedy . . . that is until I go forged
.
Thanks.
. I must not be greedy, I must not be greedy, I must not be greedy . . . that is until I go forged .Thanks.
02-18-2008, 10:47 AM
#5
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I have bumped the limiter up, but I have a built motor. If your heads are stock than no, I wouldn't touch the limiter. The biggest concern I would think would be the valvetrain. If/when you completely upgrade the valvetrain, then I would say you could look into raising it, although at your power level, if you starting revving higher and making more power, I would think your bottom end would be on borrowed time. Hope this helps
550 h.p. and 6500. you are just asking to have a new motor put in. And for some reason. #7 cylinder is weak in this motor. a # of guy have had # 7 go out. And like above vavle train on stock will not take to much of this on the springs. If by what you are saying just pull a vavle cover and look and see what is there...
02-18-2008, 01:53 PM
#6
Racer
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R.P.M. = R.I.P. for engines. While valve float is a concern, piston speed is also a major concern.
The force exerted on bearings, rods, etc. increases exponetionaly with psiton speed. Even if nothing catstrophic happens, the amount of wear on your internals will increase greatly.
The force exerted on bearings, rods, etc. increases exponetionaly with psiton speed. Even if nothing catstrophic happens, the amount of wear on your internals will increase greatly.
02-18-2008, 10:03 PM
#8
Melting Slicks
I have bumped the limiter up, but I have a built motor. If your heads are stock than no, I wouldn't touch the limiter. The biggest concern I would think would be the valvetrain. If/when you completely upgrade the valvetrain, then I would say you could look into raising it, although at your power level, if you starting revving higher and making more power, I would think your bottom end would be on borrowed time. Hope this helps
I myself have not & will not raise the rev limiter unless I wen't with a forged 346, heads & cam. Wow that would be nice Maybe one day
02-19-2008, 10:44 PM
#15
Tech Contributor
I changed to 2-bar tune and didn't set the rev limiter properly. Took it to the dyno and the guy held it to the floor up to 7700rpm on my Lingenfelter built 346. No problems, but I told him not to do it again!
02-19-2008, 10:50 PM
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02-20-2008, 01:13 PM
#17
Melting Slicks
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St. Jude Donor '08-'09
Car was at the tuners for an update with meth. Never got the meth running because it kept bursting the cheap plastic hoses. Ordering the stainless steel tomorrow. Anyway, I sent the head unit to Procharger for refurbishing and had it re installed. Car is making 8 lbs of boost and is at 551 rwhp now without the meth. Tuner says there is plenty left, almost to the point of questioning whether or not the heads are stock(?), but that is another thread. Anyway, the power is still climbing at 6400 rpms and I have heard these engines were ok at 7000 rpms if the power was there. Just curious if anyone has bumped theirs up? If it is there, why not use it. Thoughts?
02-20-2008, 03:51 PM
#19
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CI 3-5-6-7-8 Veteran
Mine is set at 7000, but I shift just past 6500 when I'm screwing around on the street (haven't been to the drags w/ the cam). For HPDE use I shift by ear which was generally a hair north of 6000 rpms... no need to wind it out everytime when not racing.
I will say though that the motor really sounds incredible that last 500 rpm from 6500-7000
The rear pistons are not weaker... the manifolds on these cars allow a straight shot to the rear pistons and the air moving at highspeed is rammed back there. The result is that the #7 and #8 can, and do, run leaner than the rest and they break. If you tuner has you uned on the ragged edge by metering at the tail pipe, chances are that your rear two cylinders are going leat at WOT.
That is why I have my car tuned to 12.5:1 (remember I'm NA) vs. 13.0:1 and I have conservative timing.
If you have a built valvetrain... it's not that you need to worry about... it's the rod bolts. If you have oem rod bolts pre-2001 they are only tested to 6400 rpm sustained. I've seen a few LS1s throw rods at VIR from being continually spun up over 6200 rpm. 2001+ LS1/LS6s received stronger sleeved rod bolts and are tested at 6900 sustained. Many suggest not spinning a motor w/ these much over that 6900 sustained limit.
HTH,
Brian
Oh and the other thing to watch is oil pressure at super high rpms... sometimes a stock pump can't keep up... I have the LS4 hight volume pump and it's a non-issue.
I will say though that the motor really sounds incredible that last 500 rpm from 6500-7000
The rear pistons are not weaker... the manifolds on these cars allow a straight shot to the rear pistons and the air moving at highspeed is rammed back there. The result is that the #7 and #8 can, and do, run leaner than the rest and they break. If you tuner has you uned on the ragged edge by metering at the tail pipe, chances are that your rear two cylinders are going leat at WOT.
That is why I have my car tuned to 12.5:1 (remember I'm NA) vs. 13.0:1 and I have conservative timing.
If you have a built valvetrain... it's not that you need to worry about... it's the rod bolts. If you have oem rod bolts pre-2001 they are only tested to 6400 rpm sustained. I've seen a few LS1s throw rods at VIR from being continually spun up over 6200 rpm. 2001+ LS1/LS6s received stronger sleeved rod bolts and are tested at 6900 sustained. Many suggest not spinning a motor w/ these much over that 6900 sustained limit.
HTH,
Brian
Oh and the other thing to watch is oil pressure at super high rpms... sometimes a stock pump can't keep up... I have the LS4 hight volume pump and it's a non-issue.
02-20-2008, 04:31 PM
#20
Safety Car
Thread Starter
I think I will leave it where its at for awhile. The more I stay in the FI Section, the greedier I get. For RR it is probably not that big a deal. When I start running out of rpms on the backstrecth at VIR , I will re-think this.
Consensus seems to be that it would be OK.
, I will re-think this.Consensus seems to be that it would be OK.
