What is a reasonably safe RPM for this engine?
Thread Starter
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Joined: Aug 2010
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From: Ann Arbor, MI
What is a reasonably safe RPM for this engine? I have a moderately built aluminum block 2008 LS2 with stock rotating assembly.
Patriot Extreme Dual valve springs
New LS7 lifters
New Comp push rods
Comp 231/239 cam with .617/.624 lift
243 heads ported by Livernois, ARP head bolts
ATI balancer
SFI flexplate, 4l65e built for high RPM
4150-style Holley intake
2002 PCM for drive-by-cable
I am very comfortable and experience with HP Tuners and log every run for wideband A/F, etc.
I started at 6500 rev limit but determined that every 200 extra RPM was lowering my ET by 1/10th. I now shift at 7000.
So, is 7000 pretty much the safe limit, or are people going higher with similar parts?
Thank you. I look forward to any and all replies.
Patriot Extreme Dual valve springs
New LS7 lifters
New Comp push rods
Comp 231/239 cam with .617/.624 lift
243 heads ported by Livernois, ARP head bolts
ATI balancer
SFI flexplate, 4l65e built for high RPM
4150-style Holley intake
2002 PCM for drive-by-cable
I am very comfortable and experience with HP Tuners and log every run for wideband A/F, etc.
I started at 6500 rev limit but determined that every 200 extra RPM was lowering my ET by 1/10th. I now shift at 7000.
So, is 7000 pretty much the safe limit, or are people going higher with similar parts?
Thank you. I look forward to any and all replies.
Joined: Jul 2007
Posts: 1,502
Likes: 177
From: ELSA, South TEXAS (956) 802-7700
I think 7k rpm is really pushing it especially if you dont have stronger than oem connecting rod bolts like arp, katech...
The more abuse like that will require more frequent oil changes and i would run a thicker oil. I was recommended 15 40 but chose to run 10 30 and feel engine is smoother...
My builder is almost identical except ls3/l92 top end
The more abuse like that will require more frequent oil changes and i would run a thicker oil. I was recommended 15 40 but chose to run 10 30 and feel engine is smoother...
My builder is almost identical except ls3/l92 top end
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I use that cam in our LS3 with shift points set at 6,500rpm and cross the line at 6,800rpm.
Fitted a slightly larger 235 243 .620 .624 113 to friends LS2 and before changing to 4.1 diff gears I ran it out to 114mph in third gear, which is close to 7,200rpm.
Fitted a slightly larger 235 243 .620 .624 113 to friends LS2 and before changing to 4.1 diff gears I ran it out to 114mph in third gear, which is close to 7,200rpm.
Thread Starter
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Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
I don't recall if it has ARP rod bolts. I did a lot of experimentation with oil pans (all documented in the insanely long oil pan thread) but don't have enough pics of the crank area to tell if ARP. Engine was rebuilt for performance by the previous owner - 24x reluctor for drive-by-cable, ARP head bolts, cam etc. Perhaps they did upgrade the rod bolts.
Engine has less than 10K on it total, be happy if it goes another 10K. I use Mobile1 5-30 and change it every 2000 miles.
BTW - I changed to the current cam - a Comp 54-459-11 cam. Piston-to-valve clearance is only .045.
Sounds like multiple "votes" not to go any higher.
Engine has less than 10K on it total, be happy if it goes another 10K. I use Mobile1 5-30 and change it every 2000 miles.
BTW - I changed to the current cam - a Comp 54-459-11 cam. Piston-to-valve clearance is only .045.
Sounds like multiple "votes" not to go any higher.
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Verdad Gallardo Joined: Jul 2007
Posts: 1,502
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From: ELSA, South TEXAS (956) 802-7700
You say youve dropped a 10th by increasing shift points. Eventually you wont improve due to being out of the cams powerband for your particular combo, and youll possibly lose or blow the motor. Once you aint improving, best to scale back down to best shift rpm combined with best et.
The LS2 has the gen 4 rods correct? They are for sure superior to the gen 3 parts.
Personally, I would leave it where you are and not worry too much about chasing that last tenth.
That engine will last another 150k miles.
Ron
Personally, I would leave it where you are and not worry too much about chasing that last tenth.
That engine will last another 150k miles.
Ron
How can you say that when you do not know what his bearing clearances are? Putting 10-60 in a stock clearance engine is probably not the best idea. 5-30 is what gm recommends from the factory and it seems to be working out well for them.
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Joined: Jul 2007
Posts: 1,502
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From: ELSA, South TEXAS (956) 802-7700
GM may have recommended 5 30 but GM never recommended modding the motor as described by op, dyno junkie, myself or others either.
Joined: Mar 2007
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From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
Throw it on a dyno to see where it makes power, then do the math for shift points/rpm drop against the rest of your drivetrain. It is the only way to know for certain what you are working with.
And don't race anything that you can't afford to push off a cliff. Give 'er!
And don't race anything that you can't afford to push off a cliff. Give 'er!
Thread Starter
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Joined: Aug 2010
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From: Ann Arbor, MI
Thanks for all the feedback.
I probably will switch to a 10W-40 synthetic oil. Car companies are going to 5W-30 or even 0W-30 to eek out a bit more gas mileage.
I fully understand that too, but I wish I knew where the RPM-of-no-improvement is. If it is well past 7000, I might rebuild the engine next winter with a Callies forged kit.
Says the man who I know was chasing "tenths" all last year with his Vette until he reached (an excellent!) 10.99. 
I'm going to rebuild or sell the engine within the next 10,000 miles anyway.
I may get it dyno tuned soon, but I consider that "cheating" as I like to design, build and tune as much as reasonably possible.
I agree about only racing cars you can afford to break.
However, I have blown one engine so far - an SBC which split the crank, block and transmission case - and don't really want to repeat that. For your entertainment: http://www.nastyz28.com/forum/showthread.php?t=196932
So, if the engine is rebuilt with a Callies forged crank, h-beam rods and pistons, what is then a reasonable RPM limit?
Something like this: http://www.summitracing.com/parts/cp...8-32/overview/
Thanks again.
I probably will switch to a 10W-40 synthetic oil. Car companies are going to 5W-30 or even 0W-30 to eek out a bit more gas mileage.
You say youve dropped a 10th by increasing shift points. Eventually you wont improve due to being out of the cams powerband for your particular combo, and youll possibly lose or blow the motor. Once you aint improving, best to scale back down to best shift rpm combined with best et.
I'm going to rebuild or sell the engine within the next 10,000 miles anyway.
Throw it on a dyno to see where it makes power, then do the math for shift points/rpm drop against the rest of your drivetrain. It is the only way to know for certain what you are working with.
And don't race anything that you can't afford to push off a cliff. Give 'er!
And don't race anything that you can't afford to push off a cliff. Give 'er!
I agree about only racing cars you can afford to break.
However, I have blown one engine so far - an SBC which split the crank, block and transmission case - and don't really want to repeat that. For your entertainment: http://www.nastyz28.com/forum/showthread.php?t=196932
So, if the engine is rebuilt with a Callies forged crank, h-beam rods and pistons, what is then a reasonable RPM limit?
Something like this: http://www.summitracing.com/parts/cp...8-32/overview/
Thanks again.
For whatever reason, I see lots of LS2's spin rod bearings. I have never figured out why it's LS2's, since they have the same crank as a lot of other stuff, and rods as well. Maybe it's due to guys in search of that last 1/10th, and willing to spin a bearing for it. I can't see taking it over 6800 without knowing FOR SURE it has good ARP rod bearings in it. Just my .02.
Thread Starter
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Joined: Aug 2010
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From: Ann Arbor, MI
Looking through receipts provided by the previous owner/builder I see it does have APR rod bolts. I recall seeing them when I last has the oil pan off.
BTW - Also have an ATI balancer and TCI SFI rated flexplate.
CURIOUS - If the bottom is rebuilt with the Callies forged crank/H-rod/pistons kit with good ARP bolts, what is then the "reasonable" rpm for the engine?
Thank you again for the continuing replied and info; it is much appreciated and hopefully useful to many others.
BTW - Also have an ATI balancer and TCI SFI rated flexplate.
CURIOUS - If the bottom is rebuilt with the Callies forged crank/H-rod/pistons kit with good ARP bolts, what is then the "reasonable" rpm for the engine?
Thank you again for the continuing replied and info; it is much appreciated and hopefully useful to many others.
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i have clevite bearings, callies crank, rods, weisco pistons, and run jo gibbs ls30 5w-30 oil... my limiter is 6700-6800... no reason to spin it higher unless you are using an intake that makes power that high... all the composite fast style intakes die at 6500 anyway... i peak ay 5800 and it just goes completely flat till redline
I shifted my cam only motor at 7400rpm and it went a best of 6.38@104.5mph at 3000lbs. like that.
I even shifted it at 7200-7300 on a .93 jet when I started spraying it after I ran it N/A.
Stock 2002 LS1 bottom end with Katech bolts and a 239/247 110 custom grind.
He has a 2008 bottom end with floating wrist pins, beefier rods and way better rod bolts than my factory motor did.
I had a composite Fast 92mm manifold as well. My boss Jonathan used to turn his stock bottom end LS1 7800rpm. He had a Super Victor with a 4150 TB, our Polluter cam, LS6 sodium filled valves, 475psi of open pressure, 3/8" push rods and roller rockers. He had a T56 trans with a 5.00 rear gear and went 10.50's and 130mph at 3050-3100lbs.
He used to literally launch it off the rev limiter.
Both cars are well documented and lived a long life without breaking parts. I'd spin that thing up 200 more RPM each time until it quits picking up.
I even shifted it at 7200-7300 on a .93 jet when I started spraying it after I ran it N/A.
Stock 2002 LS1 bottom end with Katech bolts and a 239/247 110 custom grind.
He has a 2008 bottom end with floating wrist pins, beefier rods and way better rod bolts than my factory motor did.
I had a composite Fast 92mm manifold as well. My boss Jonathan used to turn his stock bottom end LS1 7800rpm. He had a Super Victor with a 4150 TB, our Polluter cam, LS6 sodium filled valves, 475psi of open pressure, 3/8" push rods and roller rockers. He had a T56 trans with a 5.00 rear gear and went 10.50's and 130mph at 3050-3100lbs.
He used to literally launch it off the rev limiter.
Both cars are well documented and lived a long life without breaking parts. I'd spin that thing up 200 more RPM each time until it quits picking up.