More drive spacer results
04-17-2006 | 11:44 AM
#41
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From: Layton, Utah
Re: More drive spacer results
Originally Posted by Raylar
NordicFlame:
Your thread here seems as though you are upset, Chill dude! The 496Ho is Mercruiser engine not a Mercury Racing engne. GM powertrain supplies Mercruiser, Volvo, etc. with the same identical engine. The engine is rated at 42HP at the crankshaft, not at the propshaft as Mercury Racing meausres their horsepower. The HP525 Mercury Racing engine is rated at 525HP at the prop and on dynos it seems to produce about 550HP.I am curious what it would produce on Bob's propshaft dyno. Most of us in the industry have measured stock 496HO's at the crankshaft and the results seem to support GM's rating. I have not heard of anyone measuring a stock 496HO at the propshaft. The 496H0 would most likely produce about 390HP or so at the propshaft if it is measured on a calibrated propshaft dyno. Not to many of those around. I am sure that Bob's measurement of 492 or 493 at the propshaft on our kit was a good number based on his dyno, but without measuring a stock 496HO on Bob's dyno there is no way to measure a base comparison number under the same conditions. I understand Bob is a good friend of yours, perhaps you would be willing to get him a stock 496HO that he can run on his propshaft dyno.
Ray @ Raylar
Your thread here seems as though you are upset, Chill dude! The 496Ho is Mercruiser engine not a Mercury Racing engne. GM powertrain supplies Mercruiser, Volvo, etc. with the same identical engine. The engine is rated at 42HP at the crankshaft, not at the propshaft as Mercury Racing meausres their horsepower. The HP525 Mercury Racing engine is rated at 525HP at the prop and on dynos it seems to produce about 550HP.I am curious what it would produce on Bob's propshaft dyno. Most of us in the industry have measured stock 496HO's at the crankshaft and the results seem to support GM's rating. I have not heard of anyone measuring a stock 496HO at the propshaft. The 496H0 would most likely produce about 390HP or so at the propshaft if it is measured on a calibrated propshaft dyno. Not to many of those around. I am sure that Bob's measurement of 492 or 493 at the propshaft on our kit was a good number based on his dyno, but without measuring a stock 496HO on Bob's dyno there is no way to measure a base comparison number under the same conditions. I understand Bob is a good friend of yours, perhaps you would be willing to get him a stock 496HO that he can run on his propshaft dyno.
Ray @ Raylar
Just stating the facts which you just confirmed
05-25-2006 | 01:55 PM
#42
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From: Spicewood, Texas USA
Re: More drive spacer results
Just finsihed dynoing a somewhat stock 496HO on my prop shaft dyno. This engine is installed in a Nordic Rage. It was a 375 HP engine that I rebuilt. It has stock configuration forged pistons .005 oversized with file fit rings. 496HO cam, stock exhaust with turbulators removed and some exhaust porting based on Raylar's recommendation ,and a Whipple stage 1 PCM recalibration. I would expect this engine to make about 15-20 HP more than a stock 496HO. Sooooo, with that said.....drum roll please....It made 409.9 PSHP at 5000 RPM corrected using the "standard" correction method. Raw uncorrected HP was 368. Air temp was 100 degrees, 40% humidity and about 1000 ft. elevation. The final correction factor was 1.079. Unfortunately I was not able to dyno this engine before I modified it.
Bob
Bob
05-25-2006 | 02:52 PM
#43
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From: Missouri
Re: More drive spacer results
Originally Posted by bobl
Just finsihed dynoing a somewhat stock 496HO on my prop shaft dyno. This engine is installed in a Nordic Rage. It was a 375 HP engine that I rebuilt. It has stock configuration forged pistons .005 oversized with file fit rings. 496HO cam, stock exhaust with turbulators removed and some exhaust porting based on Raylar's recommendation ,and a Whipple stage 1 PCM recalibration. I would expect this engine to make about 15-20 HP more than a stock 496HO. Sooooo, with that said.....drum roll please....It made 409.9 PSHP at 5000 RPM corrected using the "standard" correction method. Raw uncorrected HP was 368. Air temp was 100 degrees, 40% humidity and about 1000 ft. elevation. The final correction factor was 1.079. Unfortunately I was not able to dyno this engine before I modified it.
Bob
Bob
05-25-2006 | 02:54 PM
#45
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From: Layton, Utah
Re: More drive spacer results
Originally Posted by Rage
I take it that the Whipple stage 1 PCM recalibration is to thank for the 15-20 additional HP over the stock 496HO or.......what?
Dave
.............
05-25-2006 | 05:01 PM
#47
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From: Spicewood, Texas USA
Re: More drive spacer results
Steve, My engine will have to wait until the winter rebuild. For a couple of reasons. The maximum my dyno will measure at the prop is 800. So my engine would be on the ragged edge. I also don't have an adequate water supply to load the dyno at that much prop shaft HP. The problem is RPM. Since it is being gear reduced, the dyno is really turning a lot lower RPM, and is holding more torque at that RPM. Thus the lower capacity. It will hold 2000 HP when run on flywheel. So, I will dyno it on the engine stand this winter. The other concern is load on the drive. You open the throttle WOT and the dyno pulls the RPM down to what you preset. Say 4000. That's like slamming the throttle wide open out of the hole. Not sure the drive would survive.
05-25-2006 | 05:10 PM
#48
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From: Spicewood, Texas USA
Re: More drive spacer results
I've dyno'd a couple of other boats just to gather some data. I did a 300HP 7.4. It measured 307 at 4600 RPM. I'd say that is pretty accurate. Next I did a 7.4 that I built up a couple of years ago with Edelbrock heads, small cam, intake and carb. It made 401 HP at 5000 RPM. I also just finished running a couple of HP500's that I modified. I did a bowl blend on the heads and switched cams to a Crane 731 grind. They made 510 PSHP at 5600 RPM...up from the stock 470. Yeh, I'm having fun and actually starting to bring in a little $$$.
05-26-2006 | 11:34 AM
#49
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From: Missouri
Re: More drive spacer results
Originally Posted by bobl
You open the throttle WOT and the dyno pulls the RPM down to what you preset. Say 4000. That's like slamming the throttle wide open out of the hole. Not sure the drive would survive.
Bill
05-26-2006 | 01:14 PM
#50
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From: Spicewood, Texas USA
Re: More drive spacer results
My main concern would be with a roots or whipple supercharged engine. The torque output is incredible at low RPM. I wouldn't worry about a naturally aspirated engine. Your engine for example probably doesn't make much more torque than stock below 4000 RPM.
