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dyno'd boat engines /now im disapointed

dmaxx3500

dmaxx3500

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chicago,
just talked to the eng dyno guy and he's run in 2 of the 3 588'' 750 hp engines and he says they run great ,but they only make 739 and 735 hp ,he's going to run the 3rd one when i get there tomorow,,im disapointed as i thought they would run better then when they were first built in 1991,,as eng cyl heads have come a long way since then,,

eng specs
588'' cu in,4.5 stroke x 4.560 bore
carilio h-beam rods
cola cranks
gm tall deck bowtie blocks
venoilia 9.6 to 1 comp pistons
solid roller cam.734 lift,274/286 dur
dart pro 1 heads 340 cfm/rech prots 2.350in/2.19exh
edlbrock single plane intakes
1250 dom holley carbs
thundervolt 4 ings with v6 modules

engs make good power up to 6500rpm
any ideas why these don't make 800+hp,thats what i was told to expect
 
oh that sux, ONLY 735 HP, lol. i think it is time to upgrade than to ones that put out over 750.
 
Don't know. It sounds like it should be there.
I'm running a tall deck in mine too. That .250" longer rod helps dwell time and makes lot's of torque. My only guess would be possibly the cam. You could go with a little more lift and duration. With that many cid and carb on it, it might wake it up more. I'm not that familiar with those dart heads either, I'm running Brodix bb2+ in mine. But I am running a Dart intake.
 
i watched the 3rd one run yesterday and im going to just put these in the boat and give up,everyone and everything ive read says these should make 800+ hp
 
dmaxx....735hp is a lot of horses! Sounds like you are disappointed that you didn't get 800hp............I guess now it's going to be all about how fast the boat/boats go.........Good luck I hope they go as fast as you want them too!:)
 
Congrats on your 2 engines!:hurray:

The horsepower numbers might seem a little bit shy of your goal.

I don't thin the numbers are too bad considering the compression ratio.

I do think that the camshaft looks to be way to small for top horsepower numbers with an engine of that displacement. Talk to another engine builder or call a good cam company.

BTW, what kind of torque numbers and curve did they produce?

Sometimes big horsepower numbers don't always produce the best speeds.
 
dmaxx3500 said:
i watched the 3rd one run yesterday and im going to just put these in the boat and give up,everyone and everything ive read says these should make 800+ hp
Click to expand...
I don't know what I was thinking when I typed that, it's a .400'' longer rod. Don't :banghead:. You're getting close to your goal. I'd have guessed that they would have made it as well.
 
torque was about 720 on all 3, yes i was hoping for 800,all 3 were within 10 hp and 5ftpds of torque,i talked to the eng builder and these are going back to try again next week,[dif cams and or timing,diff carbs or more rpms ,etc],,and blowers work great if you need more power on these [upwords of 1000hp-1400hp],ill keep you guys posted
 
dmaxx3500 said:
torque was about 720 on all 3, yes i was hoping for 800,all 3 were within 10 hp and 5ftpds of torque,i talked to the eng builder and these are going back to try again next week,[dif cams and or timing,diff carbs or more rpms ,etc],,and blowers work great if you need more power on these [upwords of 1000hp-1400hp],ill keep you guys posted
Click to expand...

I feel like the cam is going to be the secret. It might be the weak link in the setup. More duration and lift should help you take advantage of the inches and heads. But then again I'm not an engine builder.
 
Get some hours on those badboys and I can almost guarantee they'll loosen up with 10-15 more horses!
 
we talked to comp cams today and they want us to retard the cams 4 degs,and run 4 degs more timing,they think it will unlock 30-50hp,but ive never seen that from these small changes,,but since im not paying for it ill try anything
 
How much overall timing are you running? Retarding the cam should move you up in the RPM range right?
 
there going in a 42' cigarette revolution that weighs 12,500 lbs,,there are 3 of these and it should run 100+ mph,,the yellow and blue one in the first pic is a 35' mistress that has 2-454 efi engines and it should go 65-70 mph
 
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