What revs do the 2.5 boys pull?

[Taz]

Burty roofer etc etc what revs do u go up to? i know the efis have a limiter dont they 8200rpm?

[Wacky Racer]

8500 if not pulling a skier, 7800 with

[HydroT20]

..On the 2.5 EFi.

With the A49 chip, the rev-limit is 8250 Rpm, and with the A48 chip it is 11500Rpm.

There are a couple other chip`s out there also...(A-5 I think, old stuff..)

[Taz]

is there a safe realible limit?

[BluFin]

Originally posted by Taz
is there a safe realible limit?

Idle

[HydroT20]

..is the safest of course, but this an all race engine so it requires alot of "attention" anyway you look at it.

when using the A48 chip(11500), I think you really should have a lightened and ballanced rotating assembly -it keeps the bearings of the crank/rods happy.

Watch the compression and use 3% good fully synt. oil and it will hold up..Or att least mine did..think it has alot of hours.(before I tore it down)

Edit: saw now that you had a 2.5EFi, thought you had a XR2 and was thinking of getting an Efi..sorry about that-my bad..)

[JamesM]

Originally posted by HydroT20
..On the 2.5 EFi.

With the A49 chip, the rev-limit is 8250 Rpm, and with the A48 chip it is 11500Rpm.

There are a couple other chip`s out there also...(A-5 I think, old stuff..)

The A5 isnt an older chip its for the 849849 ECU the later type for the 2.5. The A36 is the older version and like the A48 and A49 fits the older 11350 ECU.

For ECU's and Chips see here .

[JamesM]

Originally posted by HydroT20
and use 3% good fully synt. oil

Think you ment 32%

As for revs depends what been done to the motor. For a standard 2.5OS in good order high 7's should be okay!!!

[roofer]

Rev it to the limit, its gonna go bang anyway, so you might as well enjoy it while it lasts

[Burty]

You want to rev to the limit dude cus thats where all the power is.
try around a 22" prop that should be about 8000rpm running bullet level

[HydroT20]

Originally posted by Johnny Boat Dude
The A5 isnt an older chip its for the 849849 ECU the later type for the 2.5. The A36 is the older version and like the A48 and A49 fits the older 11350 ECU.

For ECU's and Chips see here .

Ok, thanks-I should have checked the biggerhammer-site first, I`m new to the 2.5 EFi-Mercury thing

[roofer]

Taz your engines got an 11250 chip in.

[Burty]

Originally posted by roofer
Taz your engines got an 11250 chip in.

i wish to edit my statement then.
20" prop get her screaming dude. only thing is you will need a bigger rev counter

[Taz]

Originally posted by roofer
Rev it to the limit, its gonna go bang anyway, so you might as well enjoy it while it lasts

I dont want her to go bang though thats what im worried bout , rather take her dwn to hutchy to be rebuilt then pay for a new block!! ive seen the trouble you and burty had!! weep. ......

I was bombing along at just under 80 sog and looked at the rev counter just under 8000rpm was pulling lovely just was scared bout the expensive rebuild or worse no boat for summer!

[roofer]

If your worried about it get a set of rings fitted.

[Taz]

Yeh sounds a good idea, My compression is all even though so id like to get through the summer a little before i spend loads of dosh.
Do you know rougthly how much rings are ?
After putting a new reed in and cleaning injectors ive havent had a prob, Touch wood

[roofer]

Rings aren't cheap about £500 ish for genuine merc hipo i think.

[kiwiracer]

ive got two 2.5 ROS on my boat
we like to run them at 7800 to 8000 during a race, anything lower and the power is not there and they hate being loaded
make sure they have good water pressure and good volume
i run a fully synthetic oil and mix it at 40:1
these are a full blown race motor and probably not all that suited to recreational boating
we rebuild them after 25 hours

well, thats how we run them down here anyway

[Burty]

40:1 I was told by Jay Smith that if you are running at anywhere near 8000 rpm then you need 32:1

[roofer]

I always run mine at 30/1 fully synthetic, not that its done any good