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

Re: Upgraded engine lost speed any help?
 

Say your engine makes 400hp at 4800 rpm, but at 5400rpm it is making 450hp....where would you want to be propped for ? 400hp or 450hp ?

What if your old motor made the same 400hp at the same 4800rpm ?

Exactly......That's why same prop is doing same rpm at WOT. Note: saying this to my example, possibly not yours, I need to run some brain functions to try to compare the two engines to see what else may be causing you power issues. I'll be back with MY comparisons on your two builds later.

Re: Upgraded engine lost speed any help?
 

I see were you guys are going with that. I assume if I were propped correctly with the first scenario I may be seeing a different result. A friend loaned me his 24 pitch hydromodive 4 blade. But I have not tried it because I heard 3 blades work better on deep props. I appreciate every ones input. If this were an exact science none of us would have anthing to talk about. Any more input would be appreciated.
Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

Are you using Ethanol gas blend. I have heard from others that you can get more power out of straight Gasoline. Just a thought

Re: Upgraded engine lost speed any help?
 

You cannot get anything but E10 in Illinois or Missouri. It sucks for boats. I store it NO longer than 3 weeks.

Re: Upgraded engine lost speed any help?
 

I still want to say it is the cam. Just would hate to have you change it out to prove that I am right or wrong. I agree with your reasoning about going to a smaller prop will not gain you anything.

I do think you need to try a smaller pitch prop to at least see if the motor will turn more rpm's. You might have some problem that is causing the motor to turn more rpms and not be the cam.

When I was doing motor upgrades I could not get the motor to rap up. I could break the prop loose at 2500 rpm, rap to 4200 almost as soon as I went wot, but when the motor hit some point (do not remember the rpm) it would not rap past that point. I ended out changing the plugs, wires, coil, and sill no inprovement in the RPM. Once I changed out the MSD box I had the rpm's I was looking for.

Can you run a computer log on a run. That may give us an idea as to what may be wrong.

Re: Upgraded engine lost speed any help?
 

I have a dataloger on the program but I have not used it. I usually make the adjustments on the fly. I may try it next time I go out. I am not going to change the cam anytime soon but I am just aggrivated when I don't see results. Every upgrade I have made I have seen a 1 to 3 MPH gain. I have done all of my changes one step at a time and has given me encouragement. But when you loose MPH that sucks!!!

You make a good point with the MSD box. I am using ACCEL HEI electronic modual, Cap, Rotor and Coil, with 8.8 300+ wires. I used to run Bosch Platnum plugs but I now am using NGK BR6. Do you see any proplems here? However the only change from before are the plugs.

Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

Check the valve spring tension. You can check the seat pressure without taking them off the head. This happened to some of my motors. Very basically, the cam lift caused the springs to bounce and killed them. After two sets went dead, I went to a milder cam and the problem was gone.

This is just a thought! Since after adding 100 hp per motor, my boat went slower. It took two years to get it right.

JB

Re: Upgraded engine lost speed any help?
 

I just had the heads rebuilt with new springs & retainers. They were set up at the machine shop to cam specs. I don't think that is the problem. When you did your upgrades had you done any head work or was that part still stock?

Re: Upgraded engine lost speed any help?
 

I finally got the chance to do the cam comparisons. The lunati only shows valve events at .050" so I could only compare those.

Then.......A bell rang in my head which was 'That cyl head casting # is one I don't know of." So, I checked it out at mortec.com and found this:

3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports

Unfortunately, I have no experience with this head so I don't have anything to report to you. No experience stock and no experience with what it takes to mod them to make more power.

I just have experience with the typical 118cc / 122cc open chamber 049 and 781 large oval ports.

I apologize. i really like to help people in these dilemma's. I don't always have an answer but sometimes my brainstorming help's the person find it.

Sorry dude. I'm bummed I can't help brainstorm with you further.

Re: Upgraded engine lost speed any help?
 

BTW: since everyone's mentioning valvesprings and you mentioned your other cam wore out, are we sure this new cam is not going flat ?

This is a huge possibility with any flat tappet cam if not broken in corect (as we all know) but even more importantly now is if normal oil is used. Normal oil no longer has the % of ZDDP that keeps flat tappets alive. there are only a few oils now that do have it - some diesel, motorcycle, and racing oils. I wrote a huge thread (okay a few threads) about this over the past year os so elsewhere. if you want me to dig the threads up and provide you links to follow and read feal free to let me know.

As a side note to this: many companies don't use proper cam cores and lifters to help keep this away also.

Ton of odds against the unknowing and unfortunately, the knowing too. It suggs and really has kicked the industry on it's azz. Thus why all the Hyd rollers you see now.

Sorry for rambling.

Re: Upgraded engine lost speed any help?
 

Thanks for the input SB,
I am sure the cam went flat because of oil breakdown. I was using the stock 330 oil cooler which is about the size of a beer bottle. I am now using a 3" EMI oil/ps cooler combo. I always us Castrol GTX strait 30 or 40. I used to use 40 but since I put on the oil cooler on the oil pressure is the same with 30. I ported & pollished the heads, had larger valves & hardend seats installed, also had them milled down slightly to get the combution chamber to 110cc. Before I bought them I found some info about them on this website.

http://www.mopar1.us/headflow.html

Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

By chance what ratio roller rockers did you use and which cranes? Also what size pushrods did you change to with the new cam?

Re: Upgraded engine lost speed any help?
 

3 flat tappet wear threads from the other site:

http://www.speedwake.com/upload/show...lat+tappet+oil

http://www.speedwake.com/upload/show...lat+tappet+oil

http://www.speedwake.com/upload/show...lat+tappet+oil

Re: Upgraded engine lost speed any help?
 

Comp Cams 1.7 Roller Rockers, oversized pushrods stock length.

Re: Upgraded engine lost speed any help?
 

OK
I was not worried about any mechanical problem till now. I still have the filters from my last 3 changes. I am so paranoid after 3 engine failures in 3 years that I changed the oil 3 times in 30 hours of use. I may open the filters up just to make sure.

Re: Upgraded engine lost speed any help?
 

Some of you recomended I switch props, thinking that I am not in the correct range for the engine to reach peak RPM. I just got the boat out of storage and installed a 23 pitch 4 blade Hydromodive. I will test it tomorow and let you know the results.
Thanks for everyones input.
Jeff

Re: Upgraded engine lost speed any help?
 

This may be a dumb question, have you varified the spark plug wiring with the timing order? I drove around for a month with 2 wires reversed. Twin engines, it ran OK but one was down on power, Daa. You may want to pull the plugs and see if they are reading the same. Someone may have accidently broken one of your spark plug wires.

Re: Upgraded engine lost speed any help?
 

I assembled all of the accessories myself. I am sure the wires are not reversed I alway double check. I may pull the plugs and take look just to see if they look different. I also thought I might put my old bosch plugs back in and see if that makes a difference.

Re: Upgraded engine lost speed any help?
 

I tried the prop yesterday. The Hydrodive prop did not work well at all. I could not get enough bow lift, porpoised all over the place. If I aired out the prop I could get the RPM to 4800 but lost speed. I put my mirage 25 back on today. I am pretty sure at this point it is the cam that made the difference. Thats what I get for listening to the Tech Line for advice. I should have bucked up and went with a bigger roller cam.

Re: Upgraded engine lost speed any help?
 

jeffswav -

I checked my Holley catalog and did not see an MPI intake for the peanut port heads. Do you have one or is it for the large oval port heads ?

Where your large oval ports modified correctly for the larger valve installed ? Meaning - chamber, bowl, and throat porting ? Not modifying the chamber and bowls when installing larger valves can actually decrease airflow. Although I have not dealt with closed or semi-opne chambers, however I would think that larger valves would come closer to the as cast chamber walls and cut some airflow. Some relieving would be necessary. Again, check with head person since I have no experience with these heads.

Re: Upgraded engine lost speed any help?
 

Aren't Hydromotive's stern lifters ?
This may not have been a good prop for you to evaluate since it sounds like your boat likes bow lifters ?

I have a Mirage Plus 23" sitting on the shelf you can test if you pay shipping. It's not for sale so I need it back - before the snow flies would be fine.

Re: Upgraded engine lost speed any help?
 

Holley has oval or rectangular, I have the oval. The oval is larger than penut but smaller than large oval. I gasket matched the intake and heads and blended in. I also did the bowls and chambers. Send me your e-mail and I will send you detailed pictures.
Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

SB
I have pictures of the heads on speedwake under Cam & Head question.
Thanks

Re: Upgraded engine lost speed any help?
 

I just looked at them.
http://www.speedwake.com/upload/show...threadid=41376

The chambers look very odd.

But what I just said means schit because, again, I have no experience at all with these heads and 'looks' mean squat, especially with lack of knowledge.

Your best to talk to someone who may have intimate dealings with these castings such as Jim V or etc. Until you do I would never assume 'ported and reworked' heads mean good performance.

Re: Upgraded engine lost speed any help?
 

Crane134241..............Lunati 30219

Seat .004" 286°, 296° .....N/A
Seat .006"...N/A..........279°, 284°

.050":..... 226°, 236°......230°, 235°
Lift 1.7: ...534", .553".....540", .550"
Installed ICL.107°...............112°
Installed ECL.117°...............116°
LSA..............112°...............114°

Installed events at seat: can't really compare. Crane published at .004" and this Lunati at .006". Let's move to .050"

Installed events at .050 :
IVO...........6° BTDC...........3° BTDC
IVC..........40° ABDC..........47° ABDC
EVO.........55° BBDC..........53.5° BBDC
EVC.........1° ATDC...........1.5° ATDC
overlap ....7°....................4.5°

Re: Upgraded engine lost speed any help?
 

Thanks for helping me with the reserch. How did you figure the overlap? Could this be part of the problem? The engine does perform very well with this cam, good hole shot, midrange and idle. But the top end falls short. If anyone can tell be any more about the heads & cam I would sure appretiate it.
Thanks,
Jeff

Re: Upgraded engine lost speed any help?
 

I found some more information on the 820 heads. There is not a lot of detail, but if they put them on the Vette they must be pretty good. They were put on LS-5 & LS-3

The heads 3993820 are 1971 454 OC 365Hp and are Corvette in my book and may have other applications.
Heads were used on '71 454 Vette and '71-'72 400/402/454 applications on both trucks and all car lines.
The first cast iron open chamber head was the GM casting #3993820. This head was used for all 1971 big block applications except Corvette LS-6. It is a 2.06/1.72 valve size head with the large oval ports