More RPM, destroked 6.0?
11-22-2010, 11:38 AM
#1
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More RPM, destroked 6.0? I was reading on another thread about a guy wanting more rpm out of his LS1 and someone mentioned destroking. I don't want to argue about sacrificing power for rpm. But I was just wondering... Has anyone built a destroked 5.3 out of a 6.0 block and 4.8 crank? Stock 6.0 bore of 101.6 with the 83mm stroke of the 4.8 crank would give you 328ci. I think this would be pretty cool to build, as you could use all factory parts. Any thoughts/opinions?
11-22-2010, 12:30 PM
#4
Didnt make the power to justify the cost of it really. It did not make much power at all IIRC.
When a stock CI engine can do 7200 rpm with a proper heads/cam setup, is there really a reason to question that?
These newer engine do not abide by the old school laws that once governed all.
The idea now is, how much air can you bring in and push out? Meaning the bottom end is not the limiting factor. It is the top end, namely cyl head wise and valve train wise, that will dictate how high that engine can go.
When a stock CI engine can do 7200 rpm with a proper heads/cam setup, is there really a reason to question that?
These newer engine do not abide by the old school laws that once governed all.
The idea now is, how much air can you bring in and push out? Meaning the bottom end is not the limiting factor. It is the top end, namely cyl head wise and valve train wise, that will dictate how high that engine can go.
11-22-2010, 12:30 PM
#5
Didnt make the power to justify the cost of it really. It did not make much power at all IIRC.
When a stock CI engine can do 7200 rpm with a proper heads/cam setup, is there really a reason to question that?
These newer engine do not abide by the old school laws that once governed all.
The idea now is, how much air can you bring in and push out? Meaning the bottom end is not the limiting factor. It is the top end, namely cyl head wise and valve train wise, that will dictate how high that engine can go.
Case in point for a stock engine would be the LS7. 4" stroke (longest of the LS engines in a car from gm) is rated at a max RPM range of 7k. That is per GM ratings, and they are fairly conservative on their ratings/estimates. Of course they do use a lighter rod, but IF your engine can breathe that well, then you can do that with a 346 even.
When a stock CI engine can do 7200 rpm with a proper heads/cam setup, is there really a reason to question that?
These newer engine do not abide by the old school laws that once governed all.
The idea now is, how much air can you bring in and push out? Meaning the bottom end is not the limiting factor. It is the top end, namely cyl head wise and valve train wise, that will dictate how high that engine can go.
Case in point for a stock engine would be the LS7. 4" stroke (longest of the LS engines in a car from gm) is rated at a max RPM range of 7k. That is per GM ratings, and they are fairly conservative on their ratings/estimates. Of course they do use a lighter rod, but IF your engine can breathe that well, then you can do that with a 346 even.
11-22-2010, 12:33 PM
#6
The Cadillac Racing Team (CTS-V platform) destroked and bored its LS6 based engines to gain rpm (7,600 rpm) and horsepower while retaining the same total cubic inches. That racing program was successful. Later when the platform moved to LS2 engines they did not do this.
Since, LS engines are already oversquare, destroking is rarely called for except to meet artificial constraints such as racing regulations.
On the other hand, if you are going road racing rather than drag racing or daily driving, stroking an LS rarely makes any sense either.
Since, LS engines are already oversquare, destroking is rarely called for except to meet artificial constraints such as racing regulations.
On the other hand, if you are going road racing rather than drag racing or daily driving, stroking an LS rarely makes any sense either.
11-22-2010, 12:48 PM
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Didnt make the power to justify the cost of it really. It did not make much power at all IIRC.
When a stock CI engine can do 7200 rpm with a proper heads/cam setup, is there really a reason to question that?
These newer engine do not abide by the old school laws that once governed all.
The idea now is, how much air can you bring in and push out? Meaning the bottom end is not the limiting factor. It is the top end, namely cyl head wise and valve train wise, that will dictate how high that engine can go.
Case in point for a stock engine would be the LS7. 4" stroke (longest of the LS engines in a car from gm) is rated at a max RPM range of 7k. That is per GM ratings, and they are fairly conservative on their ratings/estimates. Of course they do use a lighter rod, but IF your engine can breathe that well, then you can do that with a 346 even.
When a stock CI engine can do 7200 rpm with a proper heads/cam setup, is there really a reason to question that?
These newer engine do not abide by the old school laws that once governed all.
The idea now is, how much air can you bring in and push out? Meaning the bottom end is not the limiting factor. It is the top end, namely cyl head wise and valve train wise, that will dictate how high that engine can go.
Case in point for a stock engine would be the LS7. 4" stroke (longest of the LS engines in a car from gm) is rated at a max RPM range of 7k. That is per GM ratings, and they are fairly conservative on their ratings/estimates. Of course they do use a lighter rod, but IF your engine can breathe that well, then you can do that with a 346 even.
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11-22-2010, 01:02 PM
#8
Solid roller right? Definitely not an average build. But VR also did a build that does well north of 8k out of an LSX block and a 4" crank. 427 ci. It only did 8.92 though. That was with some nitrous also though.
The point is, you can go back and forth on that issue if you wish, but big Ci engines are still proven to quite a bit of RPM in the LS world more and more.
None of them are average builds, but I am guessing it would cost alot less to use a crank that is more common than a 1 off.
The point is, you can go back and forth on that issue if you wish, but big Ci engines are still proven to quite a bit of RPM in the LS world more and more.
None of them are average builds, but I am guessing it would cost alot less to use a crank that is more common than a 1 off.
11-22-2010, 02:49 PM
#11
If you want to pull alot of RPM, just make sure you have the manifold/cyl head/cam to breathe that high, and the rest will work itself out. Alot of people add ARP rod bolts to the bottom end for more assurance, which is a good idea. Maybe some better bearings as well for crank and rods.
11-22-2010, 04:09 PM
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Destroking You could do whatever you like. You get what you pay for, and if one were to spend some money and get a set of good flowing heads, a good cam, and a quality valvetrain to support said cam and work with the heads, then that person would be rewarded with greater high-end power and extended RPM range, more so than by simply destroking an engine. In addition, one might become acclimated and comfortable with a smaller inch motor and want more power relatively quickly, so it would have to be disassembled and sent back to the machine shop for another expensive overhaul. If a higher-rpm capable valvetrain, high flowing heads, a nice cam and more efficient intake setup are used, that same engine could be overhauled in the future to displace more volume and would have the top end already in place to make more high rpm power.
