Looking for some input please.
Getting ready to replace the original 256 blowers with either the blower shop replacement or dyers 8-71 replacement.
If I go dyers and up the boost to 7 do I need to reprogram ecu as it already runs rich.
I read that the 8-71 will still run cooler than the 256 even with the added boost.
Was also wondering if I should keep running a NGK 7 spark plug with more boost or go back to an 8.
Would like to keep engine cooler with out a chiller so what about changing thermostat to 120

Thank you for the help

I cant answer all your Questions , but an NGK heat range gets colder as the number increases , so a 9 is COLDER than a 7 .
I would be running at least 8's in any blower motor.

Im in the same boat as you - haha

im going with a dyers 8-71 kit and cranking the boost up. you'll want to reprogram the ecm no matter what, especially if you want to run the 120* thermo. should be a nice gain with just those few things

you will want the ECU's re-calibrated. Have you considered an inner cooler?

The Blower Shop replacement is a great upgrade considering the TBI.

Have the injectors flow tested - they are an oddball injector, no longer available and no aftermarket available. Eddie Young makes a replacement setup for the 575. I did the TBS blowers when I had my top gun, they already had the whipple MOAC intercoolers with the reprogrammed ECUs when I purchased the boat.

And I'd call Eddie Young for that. He did great work on my old 575's.

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First, let me say that you should reprogram the ECUs matter what, even if you leave the motors stock. At idle they run so rich the cylinder walls wash down and will wear the bores smooth. If you have not replaced the head gaskets I would be hesitant to crank the boost in the first place, they are garbage, increase heat and cylinder pressure you are looking for problems.

So, while you have the motor/s out to replace the head gaskets, change the cams to hydraulic rollers, rering, and then go with the bigger blowers.