tomas_wallin

Yes I know that his engines are good and reliable, but it's still about 6 years old and there are some other cams etc on the market today, I will of course have the engine dynoed before it goes in the boat again so I will not loose anything by changing any parts.

This engine has pushed my Pantera to at most 89mph when new and today I cannot get anything more than 78mph out of it. I beleive it should do at least 85 in our conditions over here.

We never started it before the test just ran it on the starter for a total of a couple of minutes. So the leak down might be a bit off (but still nowhere near acceptable).

Leak Down
1: 25% | 38%
2: 19% | 21%
3: 80% | 80%
4: 53% | 55%
5: 60% | 60%
6: 27% | 38%
7: 42% | 48%
8: 23% | 34%

Compression (not the static comp...)
1: 10,1 psi | 10,7 psi
2: 10,8 psi | 10,9 psi
3: 07,0 psi | 08,0 psi
4: 10,7 psi | 11,0 psi
5: 09,4 psi | 10,0 psi
6: 10,6 psi | 10,6 psi
7: 10,5 psi | 10,9 psi
8: 10,3 psi | 10,4 psi

PatriYacht

Use the 525 efi cam. It's 236/246 at .050, .610 .630 lift, 114. Put a 4.25 stroke crank in it. Can't beat cubic inches.

Linster

6 years on a blower motor is pretty long. It probally needs to be freshened up. If you are going to do that, Rings and bearings are a must. A new oil pump, I like the Melling 10770. Look at the cam, a blower beats the exhaust valve so bad, I have seen it work hard on the lobes as well. I dont think I would do a hydraulic roller in a blower. I think a hydraulic flat tappet is more reliable on a blower motor. A blower overcomes cam timing. In my opinion, I think you do not gain much from Hydraulic rollers with blowers but you put a l lot of strain on the roller. That increases failure and rebuild times. We have used just the larger B&M cams here for years on blower motors and they seem to work great. Getting too much cam blows the charge out the exhaust. It looks like the cam you have is very close to that B&M cam. Heads are toss up, how much to you want to spend. A good freshen up would do fine on what you have. The exhaust port in the GM head sucks, but it has a lot of push coming out of it. I would up the boost to 7psi with the intercooler on the engine. Might go up a round of jets if you do that. Good Luck

tomas_wallin

Thanks alot Linster!

What cam would you recommend if I was to replace it for some reason?

tomas_wallin

Yes, I will change all bearings, piston rings, valve springs and (reatiners etc) and get the block honed and a valve job. Probably will get a set of new intake and exhaust valves as well since one of the intake valves has a fine hair crack in it. If one is about to retire then how long before the others are due...

tomas_wallin

I talked to Crane Cams and they adviced me to go with one of the following two cams:

Mech flat tappet: 131271 F-252/3574-2S-14
288º/296º @ .020"
252º/260º @ .050"
.608"/628" lift valve

Mech Roller: 138791 SR-254/374-2S-14 IG
304º/312º @ .015"
254º/262º @ .050"
.636"/636" lift valve

Pat McPherson

Boy those are real big cams for a 509...
I thought the 525EFI cam was a good idea...

Linster

I agree with Pat, way too big.

525 Hyd roller would work well with Hyd Roller

Hyd Flat Tappet is Crane 134561

tomas_wallin

This is what I got from Crane about the 525 EFI cam (16HR00004):

"but the cam you want with the cubic inch you have it may give less rpm.
every time you go up in cubic inch the duration on a cam goes away so to make the motor fill like it has a cam in the engine and have the rpm you want we have to go up in duration, but as you go up in duration the lift will go up.
all you can do is to try this combination and see if you like the cam"

jdnca1

We run Crane 651 in several blown 502/509 and they work awesome....244/[email protected] .632/.632" on 114. Peak power is ~6100 with stock GM 088's and in the 840HP range with 8# of boost, no chiller and 93 Octane....