Pulling vac @ wot on blower motor.
07-17-2013, 10:52 PM
#12
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Griff, To funny...... If I were checking at the manifold then no I would not see vac. Below the carb/top of the blower yes.Thanks SFO for the heads up. I talked to the guys at Quick Fuel today. They said that what I'm seeing is ok. They think even with a 1050 I might see slight vac. They mentioned if I were in the 3 range then I should be concerned. At that point the carb would be a big restrictor plate. Others say I should see 0 vac. A 920 cfm carb "should be able to feed a 600hp motor" but I was just concerned when I saw the vac being that I never had a blower before........
07-19-2013, 07:38 AM
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Nope. Its a SMALL 174. Merc Had a rev limit of 5200 with that blower (from what I can find out). I don't want to push my luck with running it at 5600/5800. If I had a 250 I'm sure I could spin a 30. CP, how much did you velocity weight and what kind of speed were you hitting? 77/78 feels great. Im sure 85 ish would fell better...lol
07-19-2013, 10:09 AM
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I think you have a small restrictive heat pump on that engine. It might be hurting you more than helping.
Last edited by Rookie; 07-19-2013 at 10:12 AM.
07-19-2013, 01:56 PM
#18
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Running so little timing will cause the EGT's go way up and increase the risk of detonation. I would bump the timing to 30*.
The blower is also small for for a 496. What size pulleys are you running and how much boost????
The rev limiter on a 525SC was 5350rpms and the blower was overdriven at a 2:1 ratio for a blower rpm 10,700rpms.
The max rated rpm for the 177 blower was 13,500rpms.
The blower is also small for for a 496. What size pulleys are you running and how much boost????
The rev limiter on a 525SC was 5350rpms and the blower was overdriven at a 2:1 ratio for a blower rpm 10,700rpms.
The max rated rpm for the 177 blower was 13,500rpms.
Last edited by Griff; 07-19-2013 at 01:59 PM.
07-21-2013, 05:50 PM
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The plugs show no signs of detonation and the burn on the plugs electrode look good. (mark is on the bend). I have about 30 hrs or so on this setup. I was going to bump up the timing up to 30 but the plate on the blower (Hawk Marine/ old blower/new Teflon/ great shape) listed timing at 25. I am learning as I go with a blower setup. I am one size smaller from stock on the top pulley to compensate for the Supper Chiller. Temp gun on blower intake is about 130 and I want to say the manifolds are about 170 at the base and warm on the riser. Engine temp never over 120. Run hard and have never lost boost due to heat. Griff, If you were to run 30 would you keep the V6 module (14 total) with 16 base or go back to the V8 (24 total) and base @ 6.
07-21-2013, 06:44 PM
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You want to keep the V6 module. But keep in mind it does not provide 14* of advance on a V8. I forget, but I wanna say it's like 8-10* when used on a V8. Just set the total and let the initial fall wherever it does.
Big block Chevys love ignition lead. Back in the early days of supercharging marine engines, guys thought it was being safe by retarding the fuk out of the timing. The #1 reason engines with superchargers fail is lack of fuel. Make sure you have a safe AFR, then give it some timing. This is where a dyno comes in handy.
I like to get the AFR where it needs to be, then add/subtract timing and watch the EGT. Just a FYI , mercury ran 35* total on the 525sc, and 33* total on the 600sc. Granted they were low static compression. Going from say 30 to 32 might pick up a measly 5-10hp, but it's about keeping the exhaust valves cool and cylinder temps down
Big block Chevys love ignition lead. Back in the early days of supercharging marine engines, guys thought it was being safe by retarding the fuk out of the timing. The #1 reason engines with superchargers fail is lack of fuel. Make sure you have a safe AFR, then give it some timing. This is where a dyno comes in handy.
I like to get the AFR where it needs to be, then add/subtract timing and watch the EGT. Just a FYI , mercury ran 35* total on the 525sc, and 33* total on the 600sc. Granted they were low static compression. Going from say 30 to 32 might pick up a measly 5-10hp, but it's about keeping the exhaust valves cool and cylinder temps down
