roots blower

[Duke901]

I was wondering how much compression is to much to run a blower. Because i found a blower i can get really cheap but my pistons are rated at 11.5

[techinspector1]

carbureted, 8:1 to 8.5:1

[Duke901]

Well i guess i cant use it then lol, thanks

[pat mccarthy]

i have buit them with 9.5 and 10 to 1 try to get it to10to 1 watch the boost get a msd box6 btm box.this will work no problems run good gas. try a cam on no more than 112 to 110 centers

[Duke901]

Well the pistons are rated for 11.5, so with the head gastet i should be about 10.5 or 11, i think that would still be to much for a blower and my cam is the magnum 294s.

[pat mccarthy]

you can cut some of the dome off and run a set of cometic head gaskets or open the cc up on the heads . i do not know how much you are runing this? and if you want more hp?

[Duke901]

Its not going to be a daily driver. i think i will just stick to NA

[38_chevy_hotrod]

I want to hook in on this, what is the compression of an 350 Chevy engine from about 1980.
I also can buy an blower, it is an 4-71 Weiand. Completely rebuild.

Could I run that on an stock engine?
I am going to build an high performance engine, but I was wondering if I could play with this thing on my standard one.

What may such an blower cost?

[t0oL]

if you are running 11.5:1 pistons you would have to "underdrive" the blower and it could work, maye someone @ weiland or BDS (blower drive service) would have a program that could advise you more.

10-20% underdrive- smaller pulley on blower

if i had 11.5:1 i wouldn't WANT a blower, except that it will be a really nice conversation piece/artwork on your endtable

[techinspector1]

Look at the blower boost chart, compression ratio down the left side and boost psi across the top. This will tell you how much boost you can run on pump gas and on racing gas.....
http://www.blowerdriveservice.com/techcharts.php

[38_chevy_hotrod]

According to my specs, i should have an ratio about 8:1
So i can use a blower, but can my pistons handle it.

And the question remains what should be a normal price for it.
It comes with a intake manifold a carb. he wants to have about $1800,- for it(1500 euro), i think it is to much.

[Swifster]

Originally posted by techinspector1
Look at the blower boost chart, compression ratio down the left side and boost psi across the top. This will tell you how much boost you can run on pump gas and on racing gas.....
http://www.blowerdriveservice.com/techcharts.php

And, as always, your mileage may vary . As mentioned, only use that chart as a guide. Final boost pressure will vary by engine and will depend on what other modifications have been done to increase breathing. Increasing the engine's capability to breath will decrease boost pressure due to decreasing the back pressure built into the engine.

A supercharger sized to a stock SBC with 5 psi boost, may in fact only produce 2 or 3 psi boost after porting the heads with larger valves and increased exhaust breathing, but increase power due to the ability for the engine to breath better.

[Duke901]

Cool thank you for the chart
Mike