Ported OEM 990's by ET Performance
4.600 bore x 4.375" stroke
9 to 1 Compression
Dart Intakes with prepped 850's
2 inch Spacer
Custom Hyd rollers 251/259 .680/.630 lift on a 113
34 degrees timing
93 Chevron

Best engine
680HP @6000 rpm
655#/ft @ 5000

2nd Engine
671HP @6000 rpm
652#/ft @ 5000

The torque curve was within 7% of peak for a 1000 rpm on either side.

Should make for a nice ride in a 32 ft boat.

What a waste, put them in two Chevelles :D

I agree with Bob :P

Why such low compression?

It is fairly common to run relatively low compression in gasoline marine engines, because they are expected to run on crappy 87 octane pump gas and be run hard between peak TQ and peak power for extended periods.

That just shows how streetable these things can be!!

Also neat that two identical engines are that close on HP at that level...neat stuff!

Good post!

JIM

Good job Chris

Am I reading that right??.....4.375" bore and a 4.600" stroke?!!!

Your boat should be able to keep up with Ron's (owner of ET Performance)Formula. From what I hear it's pretty fast. He does some excellent port work.

Ported OEM 990's by ET Performance
4.600 x 4.375" bore
9 to 1 Compression
Dart Intakes with prepped 850's
2 inch Spacer
Custom Hyd rollers 251/259 .680/.630 lift on a 113
34 degrees timing
93 Chevron
Best engine
680HP @6000 rpm
655#/ft @ 5000
2nd Engine
671HP @6000 rpm
652#/ft @ 5000
The torque curve was within 7% of peak for a 1000 rpm on either side.
Should make for a nice ride in a 32 ft boat.

Hi Chris, not doing many marine units here by choice, you've got me curious about a few items here. We recently delivered a 540", 9.75:1 C.R., Comp retro-hydraulic (252/262 @ .050" x .720"/.714" x 114LS), C.I. Pro-Topline 360's, and a 4500 Holley. Numbers came in at 740+ HP @ 6300 and 662 Torque @ 5000.

The fact you see iron heads should be a clue it's a "salt-water" cooled unit runs at 145 constantly normally. What we did test on the dyno is that water temp. You'll find yourself "down" 15/20 HP at those temps. Most likely from the oil. The numbers above are at normal operating temps, 180/185.

Back to my curiousity, first, fresh or salt-water cooled, second, race boat or cruiser, and last, is the unit "comfortable" way below the torque band, maybe with a few passengers on board?

All these units need the "props" custom built from the dyno sheet, this customer sends the sheet down to a custom "prop" builder in Florida, when he fist installed the unit it wouldn't "fall-out-of-a-tree" till they did the prop!
All his speed and acceleration rates are checked using GPS, he doesn't rely on the boat's "guages".

My customer wants more "all-around", when he's carrying 4 people he has a problem getting up on "plane" due to the high torque numbers in the upper RPM range. We just delivered this for this season, he's already on the "board" to return it when it ends. As I said, he wants more! We already know he will end with a "blown" unit for the best of both worlds! Thanks, Gary in N.Y.

P.S. One very important answer we gained from this particular unit is the fact with the water temps so low, even the 9.75 C.R. should have been much higher. When we opened this unit up after the first build using 9:1 originally, we found we had too many "deposits" built up on the pistons. This was the reason for "upping" the ratio to the 9.75 number the second time. Now we opened it again in March this year and the same deposits were present. What we realize is the C.R. is still too low for the operating temps. It needs more to help "burn" the deposits away. Plug ranges didn't help. This is ONLY on salt-water units! If fresh water cooling is used the C.R.'s would be fine.

Hi Chris, not doing many marine units here by choice, you've got me curious about a few items here. We recently delivered a 540", 9.75:1 C.R., Comp retro-hydraulic (252/262 @ .050" x .720"/.714" x 114LS), C.I. Pro-Topline 360's, and a 4500 Holley. Numbers came in at 740+ HP @ 6300 and 662 Torque @ 5000.

The fact you see iron heads should be a clue it's a "salt-water" cooled unit runs at 145 constantly normally. What we did test on the dyno is that water temp. You'll find yourself "down" 15/20 HP at those temps. Most likely from the oil. The numbers above are at normal operating temps, 180/185.

He runs 160 degree stats in the engines and a stat controlled oil cooler on each engine. I've not seen oil temps on a boat in the 180 to 185 range ever if I am understanding you correctly. Boat engines operate in higher constant rpm all the time. My BBC in my boat cruises at 3600 rpm for 20 minutes at a time. It's 100% stock except for Morels and an air gap intake. With a heat gun the pan is 240 degrees after a run. Most of these modified engines that I have cammed are having oil temp issues on the high side not on the low side.



Back to my curiousity, first, fresh or salt-water cooled, second, race boat or cruiser, and last, is the unit "comfortable" way below the torque band, maybe with a few passengers on board?

fresh water. The guy was on a budget and wanted to keep the stock heads. It is a pleasure boat, 32 Active Thunder V. He has stock Bravo's and we were worried about torque loading the drive so I moved the valve events around on the cam to move the powerband up.

All these units need the "props" custom built from the dyno sheet, this customer sends the sheet down to a custom "prop" builder in Florida, when he fist installed the unit it wouldn't "fall-out-of-a-tree" till they did the prop!
All his speed and acceleration rates are checked using GPS, he doesn't rely on the boat's "guages".

My customer wants more "all-around", when he's carrying 4 people he has a problem getting up on "plane" due to the high torque numbers in the upper RPM range. We just delivered this for this season, he's already on the "board" to return it when it ends. As I said, he wants more! We already know he will end with a "blown" unit for the best of both worlds! Thanks, Gary in N.Y.

P.S. One very important answer we gained from this particular unit is the fact with the water temps so low, even the 9.75 C.R. should have been much higher. When we opened this unit up after the first build using 9:1 originally, we found we had too many "deposits" built up on the pistons. This was the reason for "upping" the ratio to the 9.75 number the second time. Now we opened it again in March this year and the same deposits were present. What we realize is the C.R. is still too low for the operating temps. It needs more to help "burn" the deposits away. Plug ranges didn't help. This is ONLY on salt-water units! If fresh water cooling is used the C.R.'s would be fine.

Your front cylinders will run very cool since you have water hitting them constantly. Your better off to run about 6 to 8 piston to wall on the front do to the cold water.