Stroked 5.3
When you start moving up beyond 7K rpm, the required attention to detail increases exponentially. Hard to utilize lightweight parts in such a harsh environment that sees very high temperature and pressures. Its always easier to increase displacement and keep the RPM's down...That being said, document whatever it takes to build a reliable 1000hp+ high revving 7K RPM monster. I would much rather have a high revving LS in my opinion.
Where is the weak link on the LS when it comes to high high revs? The oiling system mostly? I am speaking to built bottom ends, not SBE.
The valvetrain can be resolved using rather conventional methods...
Where is the weak link on the LS when it comes to high high revs? The oiling system mostly? I am speaking to built bottom ends, not SBE.
The valvetrain can be resolved using rather conventional methods...
I think a lot of the stability/reliability has to do with the cam’s lobe profile. Nice gentle ramp rates and moderate lift seem to make high RPM possible with very little in the way of aftermarket parts. A stable/reliable 7k redline seems easily attainable these days with VERY little investment in an LS. Aftermarket cam companies usually had super high ramp rate snappy lobes for NA applications. Seems they are only now learning (in the past few years anyway) That a lazy stable lobe goes a long way with a turbo engine.
Capazzi is a great example. He took a literally stock 5.3 short block. Installed a cam, springs, push rods, and spun past 8k RPM for a season. All on factory lifters/rockers/heads making lots of power. Capazzi even tore down the engine for us after a season of bouncing off the 8300rpm rev limiter and dipping into the 7’s. Engine/valvetrain looked great. Pretty hard to believe… but it happened. I don’t see how increasing displacement is easier than the “capazzi method”.
Adding displacement isn’t really easier on anything. I think people just use better parts when they go that route. Larger pistons are heavier. More stroke adds additional side loads and bumps up the mean piston speed. A 4” crank also hangs the piston out of the bottom of the block which leads to rocking and increases wear/tear a ton.
Last edited by Forcefed86; Apr 11, 2017 at 09:44 AM.
When I say easier, I mean its a more common avenue and takes less thought. As far as reliability, there are many concerns, some of which you stated.
Cam lift profiles are extremely important and your right...off the shelf cams are very aggressive. Because of this I designed my own lift profiles on my cam, which took a very long time. I made sure the acceleration and jerk profiles were reasonable and there were no undesirable changes at the start and close of lift, as well as on the nose. Ramp rate can be slow, and you can still screw these up and cause all kinds of undesirable valvetrain dynamics. A lot of the off the shelf cams with light ramp rates do not have this figured out.
Additionally, the rocker ratio is not constant...it is always changing. I took a bunch of measurements of this based on a couple valve heights and plotted it. The rocker ratios were integrated into my calculations to further refine the cam lobe profile. This cam should make the power and be EXTREMELY stable.
Cam lift profiles are extremely important and your right...off the shelf cams are very aggressive. Because of this I designed my own lift profiles on my cam, which took a very long time. I made sure the acceleration and jerk profiles were reasonable and there were no undesirable changes at the start and close of lift, as well as on the nose. Ramp rate can be slow, and you can still screw these up and cause all kinds of undesirable valvetrain dynamics. A lot of the off the shelf cams with light ramp rates do not have this figured out.
Additionally, the rocker ratio is not constant...it is always changing. I took a bunch of measurements of this based on a couple valve heights and plotted it. The rocker ratios were integrated into my calculations to further refine the cam lobe profile. This cam should make the power and be EXTREMELY stable.
Another consideration when choosing a high rev motor is the intake manifold. Unfortunately for me a stock LS car intake or low profile style is all that I can fit. IIRC none of the Car intakes do all that well past 6500?
Would the Holley midrise fit? Or even the china cheapie short runner sheet metal deals? They seem to do fine past 7k. Same with some of the fast stuff.
I know this has been linked to death.. but here it is again!
http://www.hotrod.com/articles/20-ls...ifolds-tested/
I know this has been linked to death.. but here it is again!
http://www.hotrod.com/articles/20-ls...ifolds-tested/
Originally Posted by Forcefed86
Would the Holley midrise fit? Or even the china cheapie short runner sheet metal deals? They seem to do fine past 7k. Same with some of the fast stuff.
I know this has been linked to death.. but here it is again!
http://www.hotrod.com/articles/20-ls...ifolds-tested/
I know this has been linked to death.. but here it is again!
http://www.hotrod.com/articles/20-ls...ifolds-tested/
TECH Veteran
Joined: Sep 2014
Posts: 4,893
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From: Mississippi
When using a 4 inch or more crank... a real engine builder go use the CORRECT pistons and rods.
I've heard of guys with 408s going with 75k miles with no problems... and the 6.0 blocks have one of the shortest sleeves in the LS family.
I've heard of guys with 408s going with 75k miles with no problems... and the 6.0 blocks have one of the shortest sleeves in the LS family.
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Verdad Gallardo OSCS - Considering your going bigger and faster this go around, have you considered charge plumbing through the firewall with water/air IC inside? If so then you could place the throttle body towards the firewall which may gain you more hood clearance where it counts.
Originally Posted by roastin240
OSCS - Considering your going bigger and faster this go around, have you considered charge plumbing through the firewall with water/air IC inside? If so then you could place the throttle body towards the firewall which may gain you more hood clearance where it counts.
Yeah, that should definitely help with skirt wear. Making sure the bottom of the cylinders are deburred is extrememly important too. The anodizing won't help much if the cylinders are razor sharp.
You had your last engine built by HKE right?
You had your last engine built by HKE right?
It's popular in Top Fuel. I have a piston on my bookshelf from almost 5 years ago and it's completely anodized. The OEM's are even anodizing stock pistons, but usually just around the ring grooves; LS engines included.
I didn't know it was done for skirt wear. Here's all the fancy ad on's JE offers. They list anodizing for the ringland and wrist pin bore.
http://www.jepistons.com/TechCorner/PistonCoatings.aspx
http://www.jepistons.com/TechCorner/PistonCoatings.aspx
I didn't know it was done for skirt wear. Here's all the fancy ad on's JE offers. They list anodizing for the ringland and wrist pin bore.
http://www.jepistons.com/TechCorner/PistonCoatings.aspx
http://www.jepistons.com/TechCorner/PistonCoatings.aspx
Originally Posted by KCS
Yeah, that should definitely help with skirt wear. Making sure the bottom of the cylinders are deburred is extrememly important too. The anodizing won't help much if the cylinders are razor sharp.
You had your last engine built by HKE right?
You had your last engine built by HKE right?