MC X-45 RPM stop??????

(sinisalo) · (sinisalo) **Join Date: Nov 2006** 04-07-2009, 6:34 AM

My friend has a x45 -07 8.1 crusader.
When we reach about 5500 rpp- 6000 rpm.
The engine turns off almost lika an rpm stop on a car, but in slow motion...

Does someone else has this problem?
Or is normall???

(rbeckei) · (rbeckei) **Join Date: May 2007** 04-07-2009, 6:38 AM

Can you explain a little more?

(rallyart) · (rallyart) **Join Date: Nov 2006** 04-07-2009, 7:04 AM

You are way past the rev limit on that boat.
My guess is you are floating the valves and it will explode if you keep doing it.
Someone with the specs could chime in, but I think the Maximum RPM they recommend is 4800. (I might be wrong)
I've never seen a big block factory engine designed to run 5500.

(rallyart) · (rallyart) **Join Date: Nov 2006** 04-07-2009, 7:33 AM

On Crusader's website the Max RPM spec for the 8.1 HO 425hp engine is 5200 and it's supposed to have a rev limiter. Maybe your tach is wrong and you feeling the rev limiter but it MUST bet checked.

(roughrivermike)

Has he changed the prop?

(talltigeguy) · (talltigeguy) **Join Date: Sep 2003** 04-07-2009, 9:27 AM

Is he running it out of the water?

(sinisalo) · (sinisalo) **Join Date: Nov 2006** 04-07-2009, 9:58 AM

I doulbe checked with him, and we think it´s when it speed up util about 5200 rpm...
I have have had many wake boats and been around many, and I have never heard this before....
And yes it is when the boat is in the water, when we reach max speed.
if a car rpm limiter sounds like this U know
baobaobaobaobao

this is more like

baaooooobaaooooooobaaooooo
Sounds and feels realy wierd....

(rio_sanger) · (rio_sanger) **Join Date: Apr 2007** 04-07-2009, 10:06 AM

sounds like rev limiter

But the bigger question is why is he running that big block up to those RPMs?

How fast is the boat going at that RPM?

(sinisalo) · (sinisalo) **Join Date: Nov 2006** 04-07-2009, 11:19 AM

The boat is from 07, and has been in sweden since then, but he bought it 2 months ago from a (don´t) know the word for it, but the mastercraft company had to close and then the gouverment sold it to him.
So today was the first time we had it in the water... then he tested full throttle and then this started to happen...

(rallyart) · (rallyart) **Join Date: Nov 2006** 04-07-2009, 12:01 PM

Jens, it's probably just bumping on the rev limiter. It is not good to run on the rev limiter so you want to throttle back before you get to that speed.
The X-45 is a big heavy boat so it may well have had a lower pitch propeller put on it to get better acceleration. Normally you prop the boat so that it won't hit the rev limit but wakeboarding works better if the prop gives you that acceleration and control at wake speeds. So the prop you have should help there.
It is likely good for what you want and there is probably no engine damage. Some rev limiters just work slower.

(guido) · (guido) **Join Date: Jul 2002** 04-07-2009, 12:24 PM

Yup... Def hitting the rev limiter. Our 8.1 did that with the stock prop. It needs to be re-propped. That boat has plenty of power to turn a bigger prop. You should be able to go wide open without it bumping the rev limiter.

I've never seen one of those motors grenade, but I've seen plenty of headgaskets fail from prolonged high RPM's. If I were him I'd get that changed pretty quick.

Otherwise, great boat with a great motor.