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Old 12-16-2007, 11:57 AM
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Blower or No Blower, That is the question

I am planning to build a 400 SBC with the following specs.

BME Forged Pistons
4.165 Bore - 1.368 CH - Bisecting Oil Holes - Forced Pin Oiling - Anti Detonation Grooves - Lateral Gas Ported - CNC Balance Contour

Steel Crank - Stock Stroke
AFR or Dart Heads - 64cc or Larger
Cam - Not sure yet
850 Demon Carb


This is just the bare bone basics but my question is what do you guys think of adding a Weiand 177 Blower to this combo. I know that engines running blowers should have "blower pistons" and lower compression but since this is a small blower with boost of only around 7 - 10 psi, is it necessary?

What about adding NO2 to this combo? Can you run NO2 through a blower with a nitrous plate under the carb?

What rod length do you think I would benefit from the most?

Thanks

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Old 12-16-2007, 12:53 PM
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What gas are you planning on running? I have a 9.7:1 350 that I bolted a 142 on as an after thought. From the factory the blower was supposed to create about 6 psi on a stock 350. Mine has aftermarket heads with 200cc ports and the boost ended up at around 4 psi. It ran fine and didn't have any problems with 92 octane gas. However, when I put on a smaller pulley and brought the boost back up to about 6 psi it would detonate badly under load with 92 octane. It sounded like marbles in a tin can. I now mix 80% 92 and 20% 114 when I fill it up. As long as I keep my foot out of it I can get away with 92 though.

If I would have built the engine for a blower in the first place I think I would have gone for about 8.5-8.75:1 compression.
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Old 12-16-2007, 01:07 PM
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Thanks Blazin72
This will be a "Race" only engine in an 89 S10. I am building it for my son as a father/son project for the 1/4 mile strip. Fuel will be either 110 or 114 octane, nothing under. I am new to the blower thing so I wanted to ask questions before I ended up with a scrap pile. The blower came with a 6" crank pulley which I assume is their "standard" size for the 177.
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Old 12-16-2007, 02:22 PM
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youll have better luck and results by running alcohol and ditching the demon and get a holley blower carb.
(demons need alot of tweaking to run right on top of a blower)
at least for your setup
running NOS with the above spells disaster without proper pistons and rings.
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Old 12-16-2007, 07:55 PM
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You did not provide enough info to really offer solid advice. We have no idea what the compression ratio is. I doubt you will be able to make 10lbs of boost with a 177 on a 400+ cubic inch engine. If it is going to be race only then I agree you should build it to run on alcohol. If you go that route you can have decent compression and still run boost. You will be able to make good power and still be safe. The draw back is you will have to change the oil frequently.

If you are dead set on gas, it can be done and you can run nitrous with a blower.

Before you ever bolt a single part together I suggest you but the book called "Street Supercharging" by SA Designs. This will give you a good foundation of forced induction and you can build on that. There really is more to making power with a blower than bolting it on and hoping for the best.

Royce
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