A friend is rebuilding his 575sci and we've been discussing possible mild upgrades. One thought has been to raise the compression ratio to 8.5:1 when buying the new pistons. The questions are how much power would it be worth and would remapping the ECM be required? He runs 93 octane gas now and boats in water that normally is less than 80 deg. F. Also, he does not wish to run an intercooler for a number of reasons. Any input would be appreciated. Thanks

Search 575sci there are several threads about this motor. I have 2 of them with Arizona Speed and Marine upgrades. Consists of smaller top pully,ecu reprogram and msd. Picked up about 5MPH in my cat

Yes, programming is necessary with any changes you make. Adding compression is a good plan. Most opt to change the pulley on the sc to up the boost. The problem is the blower itself. They are prone to failure with increased speed. A slight change in boost may be ok, but any more than a pound or so and you will need an intercooler and run the risk of tearing up the blower. A billet 256 blower from the Blower Shop would be a nice, albiet expensive, upgrade.
Let me know if I can help.
Eddie

Change the pistions, cam (from flat tappet to hyd roller), port the heads or switch to aluminum, re-map the ECM...

Thanks guys, I guess he will be going back stock. We were exploring the idea of gaining a few ponies without the hassle of messing with the ECM. THIS IS WHY I LIKE CARBS!

You may want to consider upgrading the blower (671 or 871) and possibly keep the stock pistons (they are JE forged). The throttle bodies/adapter bolt rite on a 871. I opted for a whipple low profile intercooler/intake. I added an adjustable fuel pressure regulator and increased my fuel pressure and did not remap. Teague does this with his supechiller kits and does not remap. Not the best way to tune but it can and has been done. If you are changing the cam I would not recommend it.

All that being said...I have two blower carbs/adapter/linkage/lines/arrestors that need a new home. They came off of the blower package I bought. I would be willing to work out a trade for your throttle bodie setup.

Thanks, but the motor isn't mine

I don't know about the 650 HP Teague upgrade but he does remap on the 750. My 575 was built by Teague and he remaped my ECU and modified my throttle bodies from 650 to 700 cfm.

The blower shop 250 billet blowers look like really nice pieces. I wouldnt mind replacing my B&M 250's with them. Not sure how much i would gain HP wise, but i am sure they are of much better quality, and look awesome being Billet and all.