8-71 Blown 540 questions

**Fast9SecChevelle** · 03-05-2012, 05:52 AM

Hello, It seems that I have to turn to the boat guys again for some motor info. I'm close to finishing the build, and am concerned that I may not make the power I want. The combo is: 540 short block (8.5), total seal rings, ported RHS 320 heads 390 intake, 298 exaust @.800 lift, Super Chargers USA H.A. three point teflon stripped 8-71, two 1000 HP boost referenced Holleys,solid roller 736-727, 276-285 @.050 114 lobe sep, 2 1/8 headers with 4" exaust. Boost will be whatever it will take on race gas. Looking for somewhere near 1200 hp around 7200 rpm. Back up plan is of course an F2 procharger, but the hood already has the hole, and the blower is setting on the bench.

Looking for, and appreciate, any and all info or comments, combos or "I gotta buddy with a motor close to that that makes XXX horsepower" stories.

**gn7** · 03-05-2012, 09:04 AM

Originally Posted by Fast9SecChevelle

Hello, It seems that I have to turn to the boat guys again for some motor info. I'm close to finishing the build, and am concerned that I may not make the power I want. The combo is: 540 short block (8.5), total seal rings, ported RHS 320 heads 390 intake, 298 exaust @.800 lift, Super Chargers USA H.A. three point teflon stripped 8-71, two 1000 HP boost referenced Holleys,solid roller 736-727, 276-285 @.050 114 lobe sep, 2 1/8 headers with 4" exaust. Boost will be whatever it will take on race gas. Looking for somewhere near 1200 hp around 7200 rpm. Back up plan is of course an F2 procharger, but the hood already has the hole, and the blower is setting on the bench.

Looking for, and appreciate, any and all info or comments, combos or "I gotta buddy with a motor close to that that makes XXX horsepower" stories.

On race fuel, you could hit that number easier than shoving the thing off a tailgate.

I take it you meant 309^o intake.
What is the H.A. after Super Chargers USA?

I would have gone with 1050 dominators, and a 10-71. I think you run out of blower before you run of fuel. With the right fuel, you can easily go 25 psi with that compression ratio. getting there with a 8-71 on a 540 will be spinning the piss out of the blower. But you'll get to your goal before that much pressure.

**Fast9SecChevelle** · 03-05-2012, 02:22 PM

Originally Posted by gn7

On race fuel, you could hit that number easier than shoving the thing off a tailgate.

I take it you meant 309^o intake.
What is the H.A. after Super Chargers USA?

I would have gone with 1050 dominators, and a 10-71. I think you run out of blower before you run of fuel. With the right fuel, you can easily go 25 psi with that compression ratio. getting there with a 8-71 on a 540 will be spinning the piss out of the blower. But you'll get to your goal before that much pressure.

Thats 390 cfm intake flow, and the H.A. is "Hard anodized". I fiqured I would have to turn the boost up, Tim set it up tight it takes 11 ft lbs just to turn it on the bench. Hope it loosens up a little after it warms up.

**gn7** · 03-05-2012, 04:26 PM

Originally Posted by Fast9SecChevelle

Thats 390 cfm intake flow, and the H.A. is "Hard anodized". I fiqured I would have to turn the boost up, Tim set it up tight it takes 11 ft lbs just to turn it on the bench. Hope it loosens up a little after it warms up.

DUH!

Don't let that thing idle long if the blower is that tight. You will smoke the stripping right out of it. They usually loosen up right away, but would keep close tabs on the case temps anytime you let it idle or even run unloaded for very long until it turns fairly freely.
Alky and nitro deals can run much tightr than gas deals and not burn the stripping. Gas just doesn't cool them enough at idle.

Spray it down with this and your blower will love you for it.
[URL="http://www.dmpeinc.com/superchargers/index.php/supercharger-parts/supercharger-accessories/supercharger-gel-lubricant.html"]LINK: Supercharger gel spray

**Fast9SecChevelle** · 03-10-2012, 07:00 AM

Why is it so hard to find dyno numbers, or proven combinations that involve a Blower? Roots blowers have been around forever compared to Centrificals, however there is 10 times the information on the net comparitivley. Trying to find a proven, dyno backed combination is impossible. I thought for sure with the number of blown motors in performance boats, especially the "Hot little speedies", there would be twenty replies to this. Somebody has to know the little secret of their buddy's motor........There has to be thousands of blown jet boats out there, someone has to have some dyno numbers laying around for a hot 540 combo.

**Gearhead** · 03-10-2012, 07:47 AM

See PM

**racinjason65** · 03-10-2012, 11:29 AM

Originally Posted by Fast9SecChevelle

Why is it so hard to find dyno numbers, or proven combinations that involve a Blower? Roots blowers have been around forever compared to Centrificals, however there is 10 times the information on the net comparitivley. Trying to find a proven, dyno backed combination is impossible. I thought for sure with the number of blown motors in performance boats, especially the "Hot little speedies", there would be twenty replies to this. Somebody has to know the little secret of their buddy's motor........There has to be thousands of blown jet boats out there, someone has to have some dyno numbers laying around for a hot 540 combo.

Here is my roots set up; 565ci 9.8 deck 8.5:1 255/262 @.050 .652/.652 solid roller, heads flow 410cfm on the intake 14-71, dominators, hogan's intake with lee intercooler. overdiriven 10% it makes 11.1 lbs of boost. Dyno never captured peak torque but it was on it's way down losing 10 ftlbs every 100 rpm and made 1,020ftlbs at 4,600 rpm and made 1,049.4 hp at 6,200 rpm, uncorrected.

**gn7** · 03-10-2012, 11:38 AM

Originally Posted by racinjason65

Here is my roots set up; 565ci 9.8 deck 8.5:1 255/262 @.050 .652/.652 solid roller, heads flow 410cfm on the intake 14-71, dominators, hogan's intake with lee intercooler. overdiriven 10% it makes 11.1 lbs of boost. Dyno never captured peak torque but it was on it's way down losing 10 ftlbs every 100 rpm and made 1,020ftlbs at 4,600 rpm and made 1,049.4 hp at 6,200 rpm, uncorrected

What does the "C" on the two main needle gauges stand for? Just curious?

**steelcomp** · 03-10-2012, 11:48 AM

I did a 489 a couple years ago with a BDS 871, little hydraulic roller, made 853 @ 6700, less than 10# boost on a little race gas/pump gas blend.
Last year did a blown 540/1471, solid roller, made 1021 @ 6500 on straight 91oct, again less than 10# boost. Both engines ran Canfield 310's...the 489, they were unported right out of the box, the 540 were ported with 2.300 intake, flowed about 385. I have dyno sheets for both. Currently building a 588/1471/Canfield combination that should make well over 1K on pump gas.
Your HP goals shouldn't be a problem.

**racinjason65** · 03-10-2012, 11:57 AM

Originally Posted by gn7

What does the "C" on the two main needle gauges stand for? Just curious?

my understanding was that the 1.051 in the lower right hand corner was the correction factor and that the stppwr and stptrq on the dyno sheet meant that it was uncorrected

**steelcomp** · 03-10-2012, 12:49 PM

Originally Posted by gn7

What does the "C" on the two main needle gauges stand for? Just curious?

"corrected"

**steelcomp** · 03-10-2012, 12:51 PM

Originally Posted by racinjason65

my understanding was that the 1.051 in the lower right hand corner was the correction factor and that the stppwr and stptrq on the dyno sheet meant that it was uncorrected

Power on your dyno sheet is corrected. Clb-ft / CHp

**gn7** · 03-10-2012, 12:51 PM

I could be wrong, but if you look that is the STP correction and was figured into the STPtrq and STPpwr. You would have to multiply your numbers by .949 or .95 to get your uncorrected Trq and HP

**racinjason65** · 03-10-2012, 01:09 PM

I think you are "correct"...

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8-71 Blown 540 questions

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