Optimax to EFI power head question

[moldman]

I have a 2006 2.5 175 Optimax that is down in one cylinder. Can I mount a 2.5 200 EFI motor on that midsection? Would the adaptor plate and tuner need to be changed? Thanks, Jim.

[Fishinmymission]

yes you can very easily. Some people say swap the tuner to get an exact match to the power head some say it doesnt make a huge difference, I would swap it to the correct part number for the efi 200. You can use your plates just need to plug the coolant line that goes to the compressor pump. Routing thermostat water back into exhuast plates varies slightly between models but all this is easily mended even if its after you drop the powerhead on. Remove the powerhead and plates and if you don't damage the plates in the process feel free to reuse the plates. Feel free to come back with the specifics and pics of the power head and exhaust plates once you have the efi power head and the opti powerhead removed.

[TEXAS20225]

Jim i would change whole exhaust plate as it has some stuff on it that does not work on efi power head or figure out a way to cobb the probe thats in the plate and plug the air exhaust hole if need be that drops into the can stand plate is plugged up via casting

[moldman]

Thanks Fishinmymission and Texas20225 for your input. It is appreciated. I have extra 2 piece 2.5 EFI exhaust plates so I will go with them. The 200 block I'm building is an FF block and I was wondering how much I could open up the exhaust at the bottom without compromising the block or the adaptor. This is just a fishing motor but if there is a little more there I would like to get it. Thanks again.

[TEXAS20225]

get a225 promax gasket use it as a template and start grinding a bobs tuner goes good with it or a stock bridgeport which looks almost just like it and remember ALL 2.5 bottom plates are the same on standard motors only top is different

[moldman]

Thanks for that info.