Originally Posted by supermx96

I am in rebuilt now of mine, I have swap the rod for Callies Compstar H Beam, .030 oversize with block valve notch, Speed Pro forged piston, new aluminum Hedelbrock Performer RPM head 45 cfm more than the stock head, Crane costom grind 114lsa with less overlap 67 deg than the stock one 74 deg to keep the boost in the cylinder, estimate comp ratio at 7.5:1 - 7.6:1.

I will possibly get a porting job on the head for an extra 30 cfm or so.

I estimate at least 650HP possibly 700hp if i am lucky.

I think i will be able to keep the boost at 5.5 with the stock pulley due to less overlap on the cam and smaller intake runner 315cc instead the 325 or 335 stock.

The stock cam is very not good for this surpercharger setup.

I keep the comp ratio low for a bigger blower in future and boost arond 7 with a 250 or 671 blower.

Originally Posted by korvetkeith

7.5? Get some turbos or a centrifugal supercharger and blow 20psi on those babies.

Originally Posted by MILD THUNDER

7lbs of boost with a aluminum head is not a problem at 8.5:1, using the right blower. Add a chiller and get even more. Aluminum heads are superior in that they dissapate the heat so much better than cast iron.

You are actually better off running a bit higher static compression with a small blower. You wont have to drive it so hard to make decent boost.

If your running the 7" drive pulley, with a 2.85" upper, thats 2.45:1 blower ratio. If your propped for 5500RPM, , thats 13,500 blower rpm. I believe weiand stated no more than 13000 rpm with those blowers, and thats mainly on the street. 13500rpm for sustained wot runs in a boat, i'd be nervous about it.

Originally Posted by supermx96

Now it is time to chose between keep comp ratio at 7.5:1 or put it at 8.5:1 and keep the 177 turn at 2:1. But do you think with a 250 blower with cr at 8.5:1 and 7lb boost on 91 octane will be ok with no chiller ?
I want to built it for a future bigger blower like a 250 or 671...

I am looking for a msd ingnition box which is the best? What's about the programable ing curve box?

Also where do you suggest to set the timing advance ?

Thanks for the help!

Originally Posted by James

I have a similar blower set up. I'm switching to MSD programable this year. The programable will let you run a complex curve based on many factors including weight of the boat etc... Unlike a boost retard this will allow you to run more inital timing. The timing adjustments may provide more farvorale EGT temps while cruising or in non boost conditons, and a sweet spot for starting and idle conditions. And if all this makes no difference I can still watch porn on the laptop

Originally Posted by JD33

Anybody happen to have 1 or 2 of the stock upper pulleys for the 177 blower used on the 525sc engines?
There not the same as the street versions of this blower; different splines.
I need at least 1.....

Originally Posted by Itsallgood995

I have a 2.75 old style splined off a 250B&M. Think it takes the same pully as the 177.

Originally Posted by MILD THUNDER

The 250 Blower at 7lbs, with aluminum heads, will be ok. I did it. Just be up on your a/f ratio and timing. It will run strong. Timing 30-32* max.

I would definitly get the compression up to .75-1.0 point from where you are now.

The 177 to 250 blower is a nice upgrade. I did that. Now I am installing 420 blowers, in the hopes of gaining a little more. But its all in how much power you wanna make. I would say the 250 is good for up to 650HP or so on a 454CI. 177 about 600. In general.