Outlaw00024

I have had this engine built.. it is a 515 CI, was told it was 600hp. origionaly had a 454 thunderbolt 300hp running a 23 mirage plus at 4300 rpm 54mph.. now running this supposid 600hp with a 22p 4 blade at 4800rpm at 61mph.. the boat is a baja outlaw SSt 1996. bravo 1X upper and bravo XR lower 1.5 ratio... Thought it would be turning at least a 25 3 blade or a 26 4 blade. at 75 to 80 mph.... I am also running CMI SPORT TUBES.. didnt mention that earlier.. jetting is set at 84 secondary and 84 primary.. max timing setting is at 34..

please any one with any input would be greatly appreciated.




Build Sheet 515 CID
Base Engine 502 Chevy/Mercruiser
Component Description of Modification Parts Used
Block
Line hone, square deck bore and hone to matt 500 grit
finish. Install Campro sealed power cam bearings. Tap
and fit all threads and install all block plugs.
502 Gen V
Crankshaft
Stress relieved, radiused micro-polished to upper limits
to allow proper rod and main clearance. Cross drilled
and champhered oiling holes. Fit main bearings to
0.0028 and rod bearings to 0.0025. Rear main bearings
@ 0.0035.
GM forged 4.00” stroke, premium sealed
power bearings
Connecting Rods
Shot peened, size corrected for proper bearing fit. Fitted
with boron super alloy bolts.
GM forged 7/16” “Dimple Rods”,
premium sealed power bearings
Pistons and Rings
Pistons fitted to bore with 0.0058” clearance. File fit
rings to individual bores. Top gap fitted 0.024’. Second
gap fitted 0.026”
JE SRP premium forged aluminum
pistons p.n. 139483, sealed power
plasma hellfire rings 1/16, 1/16, 3/16
Cylinder Heads




~
Square surface correct chamber cc Fully port and
polished. Modify valve seats to accept oversized valves,
Intakes at 2.300 and exhaust at 1.880. Install bronze
valve guide liners and fit for positive seals. Set valve
heights intake and exhaust at 1.930 © 140 psi / 1.250
@39Opsi.
GM cast iron hi-performance ractangular
port. Manley stainless steel intake valves
p.n. 11530-8. Manley inconel exhaust
valves p.n. 11730-8. Comp cams valve
springs p.n. 930-16
Cam Shaft
Duration @ 0.050 lift mt - 236deg. ext - 242deg. Lobe
lift mt - 0.360, ext - 0.370. Lobe separation mt - 1 lOdeg,
ext - 1 IBdeg. Installed ~ I lOdeg mt ATOC.
Custom ground hydraulic roller p.n. HRT-
3001-3002-14-4R with matching
hydraulic roller tappets. Comp cams
retrofit push rods p.n. 7815-16.
Rocker Arms
Set at 0.00 plus 1/2 turn.
Procomp 1.7 ratio aluminum roller rocker
arms with posi-stop lock nuts.
Engine Oiling
Install oil pump and pickup to achieve proper clearance
in sump of pan.
~
Mellings hvfhp oil pump and pickup.
Dooley offshore 12 quart oil pan with
windage tray and trap door system.
Fuel System
Carburator fitted with 6.5 primary power valve and 6.5
secondary power valve. Factory primary jettiRg, 0.084
Intake manifold - Weiand team G rect
port. HP 850 CFM.DP performance

Notes: Optimum operating range 3200-4800 rpm. MAX 5200 rpm. does this sound correct

Maximum total ignition timing not to exceed 36 degrees before top dead center.


Any help on this would be greatly appreciated as this has been a total nightmere for 5 months now.

also will my stock 454 fuel pump be suffecient fuel delivery for this application.

thanks in advance.

jeffswav

First off I am not a camshaft expert I used RMbuilder for my cam and very satisfied. I would guess 525 HP. That seems like a low target RPM for that size cam and CI. Do you have aftermarket exhaust? That is needed if you do not have them. Since it looks like you did not get a dyno tune I would install a wideband O2 gage for tuning. That will let you know if you are getting to much or little fuel. Did you remove the check valve at the fuel tank, it is designed to let fuel out but not back in, it is a restriction. I have aftermarket MPI and I adjust mine with my laptop on the fly with wideband. I am running 500HP with a 24' Baja at 69 MPH. I would think you should be in the 70+ MPH range with proper tuning.

jeffswav

I just noticed you went from a 300HP engine. Did you change out the oil cooler to a larger aftermarket one? Also if this is a automotive engine you need to remove the valve in the center of the oil pad and change the outer one to the 30psi valve. The oil lines and fittings should also be improved. I am not sure about the fuel system but a O2 gage would help with that. Some of these things are to make the engine live not performance related.

niceguy

With the lower compression, I'd go with Jeffswav and maybe a tad more like 550hp... but I think 600hp would be tough with the lower compression, not impossible.

I am no cam guru either, but the operating range doesnt seem like it jives with what you've got. I would think max rpm would be around 5500-maybe higher. That is a fairly decent sized cam. Just keep this in mind: The HP500 carb'd motors are almost identical to what you have with a couple exceptions.... non-ported heads (worth maybe 20-30hp), you've got ~ 3/4 of a point more of compression (about 10-12hp) and a slightly bigger cam (with headwork maybe 20hp). Other than that, you have a Mercury HP500 and those things are rated at 500hp.

So: 500hp base, add ported heads 520-530, added compression 530-540, and a bigger cam = ~550hp.

Now, if you had a true 300hp before and you added a true 550hp, you should be able to swing a bigger prop, thus moving faster.

Will the motor turn higher than 4800? Can you run it to the rev limiter?

HTRDLNCN

why did you go to a smaller prop / Did you try the engine withe prop you had before?

PatriYacht

The Mirage prop is a fast prop. Generally good for a couple of mph more than a Bravo.

PatriYacht

From the mph increase, it would seem that the hp output is low. If you are running stock exhaust, you are likely loosing 50 hp right there. Tuning issues can cause an engine to lose a lot of hp. Make sure the ignition timing is at 34-36 total. Do plug checks to make sure mixture is correct. A new high perf. fuel pump and larger lines are a good idea also. You may be starving the engine at higher rpms. The fuel tank check valve and pickup are usually modified for more flow at this hp level also. If all else fails, at the end of the season, get your engine on a dyno and fix it from there.

JaayTeee

Try a mirage prop on that.

The drive's going to be deep on that
vintage of boat, and is not going to
perform well with a 4 blade.

If you have decent exhaust on it, I'm
guessing that combo should make 500+
hp easy.

That boat with 400 hp will generally run
right at 60, so something is amiss.

Griff

If its a 24 Outlaw and only running 61 mph at 4800rpms, then you are only making about 375-400hp.

My 24 OL had about 420 hp. I could spin a 23 mirage plus to 5400 and run 65-66mph. I could spin a 24 Bravo to 5100 and run 63-64mph.

jeffswav

I just noticed the prop change. Put your 23 Mirage plus back on it and see what that does. Bajas with deep drives like Mirage 3 blades. If that gets you up to 5200 then have it lab finished and double "Baja" cupped.