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Ls rpm preferences and expierences

90chevy396

90chevy396

Well-known member
Currently turning a 5.3 lm7 with a 2.68 and 3 blade R at 5850 WOT on the water and cruise is around 3500 with a 16X8 JB hull and it runs great so far with 3 people on the boat it is a point and shoot kind of ride but curious if there is any other guys running stock ls engines and what rpm have their engines liked.

Open to all options knowing I was turning 6200 first time I took it out and pushed good but when I held it back to 5850 it pushes so much better 16C53115-BC84-434F-8C69-B249F8494599.jpeg
 
If it's an 81.5" prop I would try 5,500 which puts the tip speed around 500mph the sweet-spot for that prop.

I have a 2.55 run an 81.5" 3 blade R and turn it 5300 its the happy medium between good cruise and still have snap with limited HP lol.

I took my tools headed to lake and spend a few hours changing the pitch and riding and 5300 is where I ended up

Just my 2 cents good luck
 
One Eyed Gator said:
If it's an 81.5" prop I would try 5,500 which puts the tip speed around 500mph the sweet-spot for that prop.

I have a 2.55 run an 81.5" 3 blade R and turn it 5300 its the happy medium between good cruise and still have snap with limited HP lol.

I took my tools headed to lake and spend a few hours changing the pitch and riding and 5300 is where I ended up

Just my 2 cents good luck
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I added 6 degrees and it dropped 400 rpm last time so next time I take it out I might just GPS it at cruise and record the rpm and bump it up 3 degrees at a time and see what it does.

I know there is some sticky green by buzzards roost probably take it back there again and test it out
 
It is a 2004 Silverado LM7 pull out nothing done to it running 24.4lb stock injectors only thing I did was go to junk yard and find a 3 bolt mechanical throttle body
 
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Little more info it is 100% stock besides throttle body it is running on a terminator x platform with wallbro 255lph fuel pump fed through -6an braided line with a sump on bottom of the tank
And the blade is cut down to 80”
 
I would run the engine at or below 5500 RPMs. The red line on that motor is 5500. Also the HSP fell off after 5300. So you aren't getting any additional thrust by running it 5850. This is why it pushed better at 5850 than 6200. 5850 made more HSP. If you want to run it 5850 or higher, I would put a bigger cam and upgraded valve springs in it.
 
CarMotorBarge said:
I would run the engine at or below 5500 RPMs. The red line on that motor is 5500. Also the HSP fell off after 5300. So you aren't getting any additional thrust by running it 5850. This is why it pushed better at 5850 than 6200. 5850 made more HSP. If you want to run it 5850 or higher, I would put a bigger cam and upgraded valve springs in it.
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Thanks
That makes sense once again this is my second boat and first gearbox boat so this is the info I have been overlooking.
 
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