LS7 = 8500 rpm
LS7 = 8500 rpm OK, OK a little hyperbole in the thread title. But as I sit here watching the Autorotica show with Dennis Gage and Jon Moss going thru GMs special vehicle collection some interesting things seem to come together. They are showing the Tiger Shark concept now. Remember the yellow C5 with the 7.0 Liter supercharged motor making 780 hp at 8.5 lbs of boost. Jon makes some interesting commments.
He describes the SB motor using the C5R heads and block and describes it as an exercise in "pushing the envelope" to see what can be driven on the street. He mentions "exotic materials" in the parts in the motor. Dennis mentions that it has a revlimiter set at 7000 rpm. Jon Moss replies that without the rpm limiter the motor is good to "about 8500 rpm". Well they won't warranty that ever I suspect (until we get 48 volt electrical systems and camless electronically actuated valves) but I am really anxious to see someone with LS7Edit take the rev limiter off their C6 Z06 and put on some mondo springs and see how fast that titanium can spin. What an interesting time for the true gear head.
Perry
He describes the SB motor using the C5R heads and block and describes it as an exercise in "pushing the envelope" to see what can be driven on the street. He mentions "exotic materials" in the parts in the motor. Dennis mentions that it has a revlimiter set at 7000 rpm. Jon Moss replies that without the rpm limiter the motor is good to "about 8500 rpm". Well they won't warranty that ever I suspect (until we get 48 volt electrical systems and camless electronically actuated valves) but I am really anxious to see someone with LS7Edit take the rev limiter off their C6 Z06 and put on some mondo springs and see how fast that titanium can spin. What an interesting time for the true gear head.
Perry
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
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From: Texas
My understanding is that the engineering of the motor is such that it COULD go that high, but will pass GM durability tests @ 7000 safely. That means a pretty fair margin of safety...
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Teching In
Joined: Jun 2004
Posts: 26
Likes: 0
Originally Posted by Gloveperson
I think 8500 would be pushing it as well. 8000 is as high as I would think it could go, even with some superman like springs.
Originally Posted by BiggerJ
Why is that? NASCAR revs to 9000-9500 using similar(if not inferior) parts. The aluminum pistons and titanium connecting rods keep the bob weight in check. The only other places to reduce weight/inertia would be the rockers, pushrods, and lifters. Don't know how much could be saved there?
TECH Resident
Joined: Jun 2003
Posts: 862
Likes: 1
From: Los Angeles, CA
Originally Posted by BiggerJ
Why is that? NASCAR revs to 9000-9500 using similar(if not inferior) parts.
how long do NASCAR engines last?
someone here must know.
i think 800 miles or less.
Winston cup motors have 3.5" stroke or less. Not 4" like the LS7.
The valvetrain on a cup car is nasty too. Ever seen a welded cam from Comp ( who supplies all but 1 cup team with cams
) Those will run you a grand or more in order to work with the flat tappets.
Comparing apples to oranges IMO. Besides, why would you want to spin an LS7 that high anyway?
The valvetrain on a cup car is nasty too. Ever seen a welded cam from Comp ( who supplies all but 1 cup team with cams
) Those will run you a grand or more in order to work with the flat tappets.Comparing apples to oranges IMO. Besides, why would you want to spin an LS7 that high anyway?
Teching In
Joined: Jun 2004
Posts: 26
Likes: 0
Originally Posted by Stone0fFire
how long do NASCAR engines last?
Launching!
Joined: Aug 2003
Posts: 216
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From: Phoenix, AZ
Old 4 bolt 454's with factory forged cranks and 7/16 rods are good to 7500 rpm on the bottom end. I don't see a little 8500 rpm action from time to time as that big of deal for the bottom end of this motor but I doubt the valvetrain could handle that kind of rpm's it without some work.
Launching!
Joined: Jan 2002
Posts: 275
Likes: 0
From: Bardonia, NY
Originally Posted by Stone0fFire
how long do NASCAR engines last?
someone here must know.
i think 800 miles or less.
someone here must know.
i think 800 miles or less.
4in===8500 completely doable with the right parts my old drag boat motor .30 454 7200rpm all duy long on a factory crank turned 10-20 --3/8 dimple rods--(the 7/16 rods come apart) and forged pistons. my 540 ci 4.5 bore-4.25 stroke turned 7500 OFF the 500 hp fogger. and this aint no car engine that ever comes off of full load (shifting or rpm drop) i held the 454 and 540 across the lake many times with no problems the 454 lasted 6 summers before it was rebuilt and all it needed was a set of valves and brngs/ rings. btw both were roller motors 454= 650 hp @7000 rpm 540= 850 hp@7300 rpm on a very conservitive dyno (thomas racing eng in cumming ga) he was also the eng machinist.
