650 Hp in Cafe

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11-21-2007, 10:44 AM

#21

jmeng

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Quote:

Originally Posted by jeff1000man

You might do a little more checking with Merc, but I think 525's actually make close to 600 hp all ready. They make 525 at the prop. Just a little food for thought.

You sure about that? The 500 efi's were 470 at the prop. When did Merc Racing stop rating them at the crank?

11-21-2007, 10:58 AM

#22

ktron

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JeffC, I saw your boat at the Marriot and I love the paint! I have seen so many white Cafe's it was a very cool change of pace for that boat. Sorry you had motor trouble. Good luck with your engine rework.

DK

11-21-2007, 12:11 PM

#23

Havasu Hangin

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Quote:

Originally Posted by SKRAMER

Hey Havasu did you put the shorties on or did the boat come like that? If you put them on what kind of gains did you get with them? How short are they? Thanks Scott

I was lucky. It had the 2" shorties on, but with 2" spacers installed, so I got to drive the boat with both X's.

I feel I did pick up a couple MPH on the top end, and the boat seems to take a better set above 75MPH.

The only downside was quite a bit of blowout getting out of the hole, but if I want the drives to live, I really don't want them hooking up hard out of the hole, anyway.

11-21-2007, 12:46 PM

#24

SKRAMER

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Quote:

Originally Posted by Havasu Hangin

Thanks for the info. I've been thinking about shorties and didn't know what to expect!!

11-21-2007, 03:07 PM

#25

jeff1000man

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Quote:

Originally Posted by jmeng

You sure about that? The 500 efi's were 470 at the prop. When did Merc Racing stop rating them at the crank?

I actually just read that on one of the insurance threads here. Ihave never seen dyno sheets on one.

I know the hp500 was 470hp though. You are correct on that.

I also read about the prop rating hp on the 525 from a tech on the tech forum. Don't remember where though.

11-21-2007, 05:05 PM

#26

JeffC

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I thought that the most you could get was a 540 or 550 out of a 502 block!

11-21-2007, 11:17 PM

#27

jeff1000man

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Quote:

Originally Posted by JeffC

I thought that the most you could get was a 540 or 550 out of a 502 block!

A 5.25 inch crank gets you a 540 with a 4.50 inch bore. Standard 502 is 4" crank with a 4.5" bore. A 4.25 inch crank with a 4.60 bore gets you a 565.

A 4.375 or 4 3/8 crank gets you a 572. if you bore it to 4.60 you get a 582". I have a couple of them in my shop right now.
I have one going out in a couple of weeks.

If you use a standard bow tie block or a later model gen V or Vi it requires the machine shop to grind out some extra clearance for the crankshaft so it can rotate. The 2 I built out of Dart blocks required crank clearancing also.

11-24-2007, 08:07 AM

#28

Magic Medicine

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Quote:

Originally Posted by jmeng

You sure about that? The 500 efi's were 470 at the prop. When did Merc Racing stop rating them at the crank?

When I was at Mercury racing they were dynoing a few 525's, the pull I saw made 543hp. The dyno operator said they make a consitent 540 plus hp. I think at some point they started to under rate the power on all the "blue" motors.