First 2.5 mods

[DangerNewb]

You're gonna need an extra 100hp to get 10mph. Spacer plate, reeds, stuffers, cut heads, tune etc will get you about 3 or 4 mph with a high performance modvp hull. Just get it running like it's supposed to run and be happy.

[Merc 2.5]

120 -130 is stock compression. Just get everything else straighten out and u mite b surprised, last boat I worked on 18ft skeeter with 150 gained 9mph by just making it run like its suppose to ,didn't change nething else except reeds

[CHEVYMAN434]

Ok,thank you..I had one more question for you guys though..So when you run 93 octane fuel do you worry about the ethanol in it? They dont sell ethanol fee in premium here..

[JCSmile]

Tighter heads to 34 cc, most guys change to a shorter exhaust tuner for the rpms, you might consider changing to a longer one for the torque (maybe use a 150 tuner?). If you really want to tune you can get a Brucato ACU or PCU which are ECU replacements that are fairly use friendly to change fuel delivery. Keep in mind these are 2 strokes so you don't have AFR, get a pyrometer and read plugs/piston wash. Experimenting with props is usually where the biggest gains are seen.

[CHEVYMAN434]

You have any idea how many thou i would take off the heads to get to 34cc?

[nitro_rat]

34cc heads work great on a high performance hull where there isn't nearly as much load as pushing a big toon. So does 24° of timing advance. Your toon will probably be into detonation and melt down at those figures! I'd really leave it alone. Is it really worth spending thousands of dollars and burning it down to go 52 mph as opposed to 51 mph?

I doubt you will see a significant difference in performance running an XR6 150, 200, or even a 225 pro max on the toon. Infact, the lower hp motor will probably have better take off!

As a hot rodder surely you understand that the 502 in the drag car has different heads, cam, carb, timing, etc from gthe 502 in the crew cab pulling the trailer? You are talking about putting the motor out of the drag car in the tow pig. It might get you home after the race but the 500 hp motor won't pull the trailer as good as the 250 hp truck motor did...

To answer your question, usually .060-.065" has to be shaved to get to 34cc. Each head is different. You have to check the cc's as you go...

Most guys cutting boat heads are using a mill. If your automotive machinist has a rotary broach it's easeir to cut 2.5 heads that way.

[FMP]

Or this
https://www.screamandfly.com/showthr...-250-EFI-2500&

[Merc 2.5]

Take Nitros advice and don't cut heads , the load ur gonna b pushing with tite heads will melt down ur motor, just to much load , everyone wants more speed and that's fine but do it safely , that motor on another hull will do really well with those mods but u won't c a difference on the toon. Not trying b negative just trying save a motor

[CHEVYMAN434]

Ok awsome..Thanks guys..So flywheel,reeds,stuffer,injectors cleaned and flowed and ecu checked over it is..Will post results when i get em..

[Merc 2.5]

R u changing from black 40 amp to red 40?

[Merc 2.5]

Same thickness? They make a red 16 amp that wont work with 40

[tlwjkw]

leave tha "black" one on it.. pushin' a turd tha little motor needs all tha help it can get!

[FMP]

Build a bigger motor, sell the little motor?

[CHEVYMAN434]

Yeah..the guy i got here doing it says it is just lighter and help it get up out the hole..

[CHEVYMAN434]

Well damn,i thought this engine i have is a big motor.lol...Went from a 2 plus 2 125..What else would i use? A 3 litre 300 plus?