2.5 efi pistons

[roofer]

Originally Posted by scooby_hugh

so would a promax 225 be able to be tuned to 250hp or a 280 efi be detuned to 250hp (probably just by limiting rpms) which would last the most hours roughly?

You could get 300 +hp out of a Promax if you spent enough money on it . I know of one that will try and take a Phantom over 100 mph at Coniston this year .Why would you de tune a Merc 280 efi , they are the best performance engine Mercury ever made .

If you left the Promax standard and maintained it properly it should last for 100's of hours.

[scooby_hugh]

the reson for detuning would be to make it last longer but thats probably a b ad idea, i think the promax would be a better choice for me, whats a rough price for a decent one?

[roofer]

Originally Posted by scooby_hugh

the reson for detuning would be to make it last longer but thats probably a b ad idea, i think the promax would be a better choice for me, whats a rough price for a decent one?

3/4k depending on gearbox and mid section, good luck finding one you don't see many for sale.

[Jay Smith]

Big HP can be extracted from most any behind the liner fed 2.5. Steel or aluminum sleeved engine ( except IMO exhaust relief sleeved motors ) ... The "issues" are not the rotating assembly it can be machines to duplicate any block port mapping than comes in a 2.5 bore configuration ( 260, Drag etc.. ) The issues now becomes feeding this new found HP with proper fuel / air mixture to make it live.. You can't feed a racehorse with a pony diet. I have built many Prop Max from mind to wild ( in fact I am building one this morning ) If the builder gets over zealos with a grinder and tries to over power the fuel system the engine will fail. With the wilder Pro Maxs that I build I use Brucato ACU ( ECU ) and their SVS air induction with great success. I also use the Wizard forged racing pistons with the proper clearance forged to steel application ( .008" ) .. This motor that runs equal to his brothers Drag motor on the same hulls has been running successfully on a bass boat for over 2 years and has many many trouble free hours logged...

Jay

[scooby_hugh]

Originally Posted by roofer

3/4k depending on gearbox and mid section, good luck finding one you don't see many for sale.

why is it there arent many for sale then? i might have to get a 2.5 efi after all then!

Jay, ideally a decent promax built by you would be my choice but i dont think i would be able to afford it, just out of curiosity how much would one like you mentioned cost? and what is the price for a std used promax over there?

[scooby_hugh]

Also whats the difference between the 200 and 225 promax?
cheers

[Jay Smith]

200 Pro Max is a 5 petal front half and a 225 Pro Max is a 7....

Jay

[scooby_hugh]

Originally Posted by Jay Smith

200 Pro Max is a 5 petal front half and a 225 Pro Max is a 7....

Jay

is that all? is all the porting the same? i would assume they are mapped differently do they have the same ecu? what would be required to turn a 200 into a 225 promax?
cheers

[Jay Smith]

The difference between a 5 and a seven petal front half is VERY noticeable... The 5 petal has more bottom end torque and turns less rpms but has more bottom grunt the 7 petal is for lighter boats and turns more RPMS and has less bottom torque but will breath better on top..

Jay

[scooby_hugh]

so the only difference between the 200 and 225 is the front half?