kennyo

You need a new builder.......

larby

Quick update...

My motor is actually 8.81:1, so pretty close to 9:1.
According to the PDF linked earlier, this only equates to below 12:1 effective CR at below 5 psi boost, so not much.

I'm only looking to make 600hp max, as my bravo definately won't cope past that. Is it really worth me bothering with the blower and any potential issues, or am I better off buying a set of stelling headers I can get, a decent cam and building a mild N/A motor, which would also be kinder on my drive?

Cheers, James

blownhammer2000

iTrader: (1)

you are gonna have to baby that bravo if its a stock setup, i think there only good to around 400hp, with 600 its a ticking bomb, if you have the coin to at least upgrade the internals on the drive and do the blower, go for it, don't forget external steering comes into play aswell, if not i would go with the mild n/a build until you can do it right

Griff

Bravo's can handle 600hp if driven right. The Merc 600SC used to be paired with a regular Bravo, as was the 500HP and 525SC.

Griff

Get some mild port work done. It will add about 2cc of volume to the chambers and lower the static Comp ratio to about 8.7 and will also flow better. Then use a .040 Cometic head gasket. Run 4-4.5# of boost and call it good.

blownhammer2000

iTrader: (1)

i stand corrected, i'm learning alot from you lately griff!

Boat1

One clarification may be needed. Most vovlo penta engines use the GM Vortec style cylinder head. If this is the case the combustion chamber is very prone to detonation. If it has standard GM style heads, I agree with everything said previously. Thanks.

Raylar

Volvo DP high performance engines in the big block family do not use the GM Vortec (454) style head and combustion chamber but use the GM performance BBC rectangle port standard BBC combustion chamber and are not more prone to detonation.
Iron heads under big boost with low octane fuel, lean burn or to much timing will tend to detonate no mater what the combustion chamber size and type and tend to do so quicker than an aluminum head of the same type does.

Best Regards,
Ray @ Raylar

Boat1

Thanks Ray, I just bought a take-off intake and injection set-up and was expecting it to fit the GM heads but it is for the GM Vortec style. Do your aluminum heads have this bolt pattern to accept this manifold. I cant even find donor steel heads to put an engine together. Thanks.

FIXX

iTrader: (2)

what does the intake look like?? Sounds like you have a 8.1l(496) intake then and not the 8.2 l (502) how mant ports in the lower manifold including the water ports,if theirs only 8 ports then it may be a 8.1 liter intake set up.