Upgraded engine lost speed any help?
 

Hello everybody,
I am back again after having misfortune this spring with engine problems. Good news is the engine is running great exept for top end. I am running a 1994 Baja 236 with Cuddy 4000 lb Dry. Mirage plus 25 pitch lab finnish with more cup for more bow lift. Bravo 1 Drive with propshaft centerline 8" below the bottom of boat (I know way to deep). I realy have to air out the prop to get max speed. I changed the heads, cam and plugs.

Here is what I had before.

65 MPH GPS 4600 RPM
489 Stroker engine
Forged Crank, rods & pistons
Holley MPI with 42 lb injectors, 1000 cfm throttle body
Crane Cam "241" hydraulic flat tappet with 226/236 duration @ .050 .534/.553 lift
GM penut port heads with manley valves 2.065 int 1.725 exh
8.6 to 1 comp 91 octain E10
EMI exhaust with long stainless risers
Electronic HEI ignition with Bosh platnum +4
36 deg of timing

Here is what I have now.

63 MPH GPS 4400 to 4500 RPM
489 Stroker engine
Forged Crank, rods & pistons
Holley MPI with 42 lb injectors, 1000 cfm throttle body
Lunati EFI "30219" hydraulic flat tappet with 230/235 duration @ .050 .540/.550 lift
GM Large oval port heads "820's" with valves 2.19 int 1.88 exh
EMI exhaust with long stainless risers
Electronic HEI ignition with NGK plugs gaped at .0425
9.3 to 1 comp 91 octaine E10
34 deg of timing

The engine seems to run better with less timing than before.

I have a ton of money in this thing and for right now I am looking for a little input on why I did not pick up the 4 or 5 MPH I was looking for.

Any input would be appreciated.

Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

Cam not degreed correctly?

Re: Upgraded engine lost speed any help?
 

Machine shop installed the cam this time. I would assume it is correct. I will call the shop tomorow and ask him details.
Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

I left off a couple of details about the engine but they were the same before and after.

Comp Cams Roller Rockers
Double Roller Timing Chain
K&N Air Filter

Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

Rev limiters not moved up??????

Re: Upgraded engine lost speed any help?
 

Are us using the same efi program with both engines? Does the Holley efi system use an O2 sensor?

Only 2 major diferences are the heads and the cam.

If I was to guess I would say the camshaft is the problem, but I do not know anything about this cam.

Re: Upgraded engine lost speed any help?
 

OK, Good questions

The rev limiter is set to 5200 RPM.
I am using the same PCM on both setups.
I am using an O2 sensor.
I did some extensive tuning on the cool mornings over labor day. I got all I could get with laptop programing. I actually felt pretty good because before that I was getting 55 MPH. I do think it may have to do with the cam but I want to see what everyone else thought. The reason I swaped the cam was because of failure, probably due too oil breakdown. I have a EMI oil cooler now. I thought this cam would be better because is was made for EFI. Most people are familiar with the Crane but here are some more details on the Lunati.

EX CLOSED ADTC 1.5*
EX OPENS BBDC 53.5*

IN OPENS BTDC 3*
IN CLOSES ABDC 47*

LOBE SEPARATION 114*
CENTER LINE 112*
THE ABOVE CENTER LINE WILL MAKE THIS CAM 2* ADVANCED

I no longer have the cam card for the Crane but I can find the info if anyone needs it.

Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

At the RPM you are turning you're probably making less HP than your old setup. Reprop it to allow it to turn at least 5000 RPM and it will wake up a lot.

Re: Upgraded engine lost speed any help?
 

I agree, you need more rpm, try a lower pitch prop and see what it does at some more rpm. The head work and cam probably won't see improvements below 5k.

Re: Upgraded engine lost speed any help?
 

Sure a lower pitch prop would turn more RPM's, but I am looking for more speed. I would have thought this setup would have given me the 5000 RPM @ 70 MPH with the 25 pitch prop. If I turn 5000 RPM's with say a 23 pitch prop that would still only give me 65 MPH? It does not make sense to me that I should make an upgrade and loose speed. My next upgrade will be to raise the drive height but that will have to be done later. For now I need to find out if this cam is not a good one for a Boat. If anyone is a cam expert please take a look at the cam card.

HERE IS THE OLD ONE
http://www.cranecams.com/?show=brows...tType=camshaft

HERE IS THE NEW ONE
www.holley.com/30219.asp

Thanks,
Jeff