Mistress repower #2 begins....
12-10-2014, 11:08 AM
#51
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Location: Olmsted Falls,Ohio Marblehead,Oh
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76-78 mph = 650+ and if it goes over 78 I will chit myself and then pull the RH drive since I will probably have smoked a gearset lol
12-10-2014, 11:48 AM
#52
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twin Holley HP850s, the new design / compisite bodies they came out with. They are a little on the small side for my application, but have proven themselves on the dyno as "adequate". I would think carbs and heads are limiting factor on my setup, more so the carbs I would think.... Can always change out if needed.
https://www.holley.com/products/fuel...rts/0-80804HBX
Comparable flow numbers to 950s is what I understand. I couldn't tell you what the limit is, but we have reached our goal.
https://www.holley.com/products/fuel...rts/0-80804HBX
Comparable flow numbers to 950s is what I understand. I couldn't tell you what the limit is, but we have reached our goal.
I would think you'd need a minimum of 950cfm. My current ones are 850cfm and it works fine... so it'll be interesting to find out what changes they make.. Hard to overcarb a blower motor.
I was considering dominators .
Last edited by ICDEDPPL; 12-10-2014 at 11:53 AM.
12-10-2014, 12:54 PM
#54
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I've decided on the 1050cfm Quick Fuels, boost referenced blower carb, ready to go. Got any pics of the black carbs on the motors? I was considering going with those... With black manifolds might look kinda cool.
I would think you'd need a minimum of 950cfm. My current ones are 850cfm and it works fine... so it'll be interesting to find out what changes they make.. Hard to overcarb a blower motor.
I was considering dominators .
I would think you'd need a minimum of 950cfm. My current ones are 850cfm and it works fine... so it'll be interesting to find out what changes they make.. Hard to overcarb a blower motor.
I was considering dominators .
Sorry ICED, my computer with pics went down so I do not have pics of carbs. Will try to locate.
Here:
post #2766 & #2793
http://www.offshoreonly.com/forums/c...ee-em-277.html
12-10-2014, 05:13 PM
#56
Registered
I've posted this before, but, just for conversation sake.
On my little blown 468's with 420 blowers, I have twin 850 Holleys. This past summer, I had changed the jets in the driveway on the trailer. Took boat up to traverse city for a fun run that next weekend. I noticed while on the fun run, one engine was down about a full pound of boost. Both would be exactly at 6psi on the gauge at wot normally, but port engine this time was at 5psi. . I thought I had a belt slipping, or maybe the blower was hurt, or something going on. Got back to the marina later that day and checked things out. No belt dust, nothing visual i can see. Then I pulled the flame arrestors off, and put the throttles to WOT. Went back and looked at the butterflies. DAM! 1 carb the secondaries were just barely cracking open. I had pinched the accelerator pump arm when installing the bowl, and it was keeping the secondary on that ONE carb from opening.
Point of the story. While the so called "calculator" says my little engine only requires about 1150CFM, I had 1275CFM of carb flow, but it was still costing me 1lb of boost, and about 200RPM on that engine. Probably 30-40HP. Now, I could run a pair of 650's on that blower, and "Make it work", by pulleying the blower faster to make the boost. But, just because it "works" doesnt make it better. Most guys will say "750's" are plenty for that build, etc, but the only real way to tell, is swap carbs back to back, prefereably on a dyno. Just because you make XXX HP with a certain carb, doesnt necessarily mean its the best carb for the application. Roots blowers push air pretty good, they are not good at drawing air in.
I would like to think Mercury back in the day, when doing some R&D, found their to be some sort of advantage to running a pair of 1050 dominators on a 900sc engine. It wasnt cost, fuel economy, or driveability thats for sure, so something had to make them choose dominators on that engine, while the 800SC (700HP at the prop) engine, utilized twin 850CFM carbs.
On my little blown 468's with 420 blowers, I have twin 850 Holleys. This past summer, I had changed the jets in the driveway on the trailer. Took boat up to traverse city for a fun run that next weekend. I noticed while on the fun run, one engine was down about a full pound of boost. Both would be exactly at 6psi on the gauge at wot normally, but port engine this time was at 5psi. . I thought I had a belt slipping, or maybe the blower was hurt, or something going on. Got back to the marina later that day and checked things out. No belt dust, nothing visual i can see. Then I pulled the flame arrestors off, and put the throttles to WOT. Went back and looked at the butterflies. DAM! 1 carb the secondaries were just barely cracking open. I had pinched the accelerator pump arm when installing the bowl, and it was keeping the secondary on that ONE carb from opening.
Point of the story. While the so called "calculator" says my little engine only requires about 1150CFM, I had 1275CFM of carb flow, but it was still costing me 1lb of boost, and about 200RPM on that engine. Probably 30-40HP. Now, I could run a pair of 650's on that blower, and "Make it work", by pulleying the blower faster to make the boost. But, just because it "works" doesnt make it better. Most guys will say "750's" are plenty for that build, etc, but the only real way to tell, is swap carbs back to back, prefereably on a dyno. Just because you make XXX HP with a certain carb, doesnt necessarily mean its the best carb for the application. Roots blowers push air pretty good, they are not good at drawing air in.
I would like to think Mercury back in the day, when doing some R&D, found their to be some sort of advantage to running a pair of 1050 dominators on a 900sc engine. It wasnt cost, fuel economy, or driveability thats for sure, so something had to make them choose dominators on that engine, while the 800SC (700HP at the prop) engine, utilized twin 850CFM carbs.
12-10-2014, 08:11 PM
#59
May, what are you talking about, if it is May when they are done, cum on man, summer is half over by then.
