Help/recommendations for a HP 500 EFI
 

I have a 2000 HP500EFI in a 29 foot Velocity, the engine is stock except for Eddie Marine exhaust with the long stainless risers, it has a set of Canfield Alu. heads that have been CNC ported along with the combustion cambers,the heads have been milled .030 to bring the compression up to a little over 9 to 1, the CMU has be recalibrated by Tyler Crocket and it has a K&N flame arrestor. The port size is 319 if I remember right. The boat runs about 73 GPS now, would like to run close to 80 as most 29's Velocity's do with 525's in them.

Are the Eddie Marine exhaust hurting my performance that much as compared to the stock tube exhaust that comes on a HP 500 EFI. Do I need to try and find a set of these exhaust somewhere to replace my current set up?

The 2000 tech manual says the cam in the engine has: 211 degree duration intake and 227 degree duration exhaust with a .581 lift for both valves. Would a cam change be worth the time and money?

Any other recommendations from anyone other than a blower or supercharger. I do not want to go that rout yet. Thanks in advance for you help.

Re: Help/recommendations for a HP 500 EFI
 

I thought HP500EFI's came with CMI exhaust? If anything, they look much better that the Eddie Marines. Your speed sounds low. It sounds like you may not be putting out the 470HP that the 500's are rated at. I've read posts from other 29 Velocity owners that are going that fast with a 496HO.

Re: Help/recommendations for a HP 500 EFI
 

Thanks Dave for you response, I think that the HP 500 EFI engines do not come with exhaust on them, you have to purchase them extra. At least mind didn't come with exhaust.

Re: Help/recommendations for a HP 500 EFI
 

I was thinking the first 500efi's came with the gils????? like the carb hp 500's

After that they came with the CMI's

Re: Help/recommendations for a HP 500 EFI
 

500 EFI cam specs are
230*/236*
.598/.610"

I'd be looking at the exhaust.

Re: Help/recommendations for a HP 500 EFI
 

If you're running the stock HP500EFI cam, I would not think the ECU would need to be recalibrated with just better flowing heads and a small bump in compression. You may want to ask Tyler if just a little more fuel pressure would be a better way to go.
The headers would help some but I'd also be looking at other areas of your setup.
What kind of prop slip #s are you seeing?
To run close to 80, you will need like 5200+ motor rpm, 28p+ prop, 1.5 drive.

Re: Help/recommendations for a HP 500 EFI
 

Jay thanks for the response, but the 2000 HP 500 EFI tech manual I have says that the cam specs are as written above.
Maybe the carbed engines have this cam or the older engines. I am really confused now.

Re: Help/recommendations for a HP 500 EFI
 

Pat the prop is a out of the box bravo 28 pitch with a 1.5 outdrive. The engine rpms' are about 5100 to 5200 with the speedo say around 77 to 78 and the GPS at 73.6. I thinks this is slow for this set up.

Re: Help/recommendations for a HP 500 EFI
 

The slip is a bit high but not horrible. Have you asked others that have your boat what prop they run?

Also, I edited my post. Did you get that part about the ECU?
I had an ECU reprogrammed 3 times and the stock calibration was still the best on my modified engine... :rolleyes:
If the calibration is not done on a dyno, it's a crap shoot.

Re: Help/recommendations for a HP 500 EFI
 

I will give Tyler a call and see if maybe the stock settings other than the RPM limiter should be reprogramed back into the computer, the engine stumbles and runs rough between 1200 rpm and 2000 rpm, after that it cleans itself out and runs fine. The CMU might be the problem. Other 29 Velocity's with 525's are all running 27 pitch, 5 blade Hydro. props and are running 82 to 83 GPS @ 5200 rpm.

Re: Help/recommendations for a HP 500 EFI
 

You do not know what engine you really have. To call it a 500EFI would be a miss statement. Sounds like a engine that was assembled and used some EFI parts but started off something else. The stumbling to 2000 RPM sounds like it could have a cam with tight lobes or too large of a cam. The engine cant respond until enough vacuum is established. That also might be why it has a slow top speed. Either way, can you find out who built the engine & what is really in it?

I have had Velocity's in the past. They run very consistant from hull to hull with the same HP. If a 525 EFI runs 82MPH, you are under 500HP by a good amount.

Re: Help/recommendations for a HP 500 EFI
 

Remember that Merc HP525's produce about 540HP at the flywheel and have a much better set of headers. I don't think exhaust alone would give you much more that 25HP over the Eddie Marine manifolds and at about 1 mph per 15HP you are probably not going to see more than 1-2 mph max. If your cam specs are right you are a little short on what you need to make 525HP plus in that motor. I would look at lets say 230 to 236 intake and about 240 - 244 exhaust with about the same lift you are showing now. Use a 114 to 116 lsa for the efi. Make sure the cam is degreed in at straight up. The stumble problem sounds like a little fat in the fuel curve at that point and maybe not enough timing at that point. This issue will most likely disapear with more programming and Tyler is an expert in this area and I am sure he can correct that. Without a better cam , better exhaust and a 5400rpm rev limit I don't think you will see the eightys. Just takes a bunch of careful tweaking and the required horsepower and torque.

Good Luck,
Ray @ Raylar

Re: Help/recommendations for a HP 500 EFI
 

Thanks everyone for the replies, the engine is a true 2000 HP 500 EFI, it was a complete engine(take out) except for the heads. Everything for the engine and off the engine was there right down to the head bolts. I took the engine ID number and ran it by Mercruiser and they told me the history on the engine. The cam specs that I quoted came out of the 2000, 500hp service manual. The cam looks to be very mild for a 500 but maybe thats how Mercruiser detunes a 525 down to a 500. What do you think.

Re: Help/recommendations for a HP 500 EFI
 

These are the spec for the HP500EFI.
Your manual is wrong.
The HP500EFI came before the HP525EFI...
The 525 has a bigger cam and aluminum heads.

If the stock 500EFI cam is in the engine, I would ask Tyler to remap back to the stock calibration. I bet the stumble would go away.
I believe that your engine will make peek power at about 5200rpm with a 500EFI cam, so 5400 rev limit is perfect.

If you have the time and $$, the HP525EFI cam and headers would really wake up your engine. The Eddie Marine manifolds are probably negating the extra flow of your nice aluminum heads.

Re: Help/recommendations for a HP 500 EFI
 

Ray why would you want the 114-116 ls with a EFI. Would you mind explaining it to me please. Does it have to do with overlap?

Thanks
Rob

Re: Help/recommendations for a HP 500 EFI
 

Good Question Rob, my guess is that the engine will make more vacuum at low rpm...

By the way, I just received some HP500 fuel injectors. The cam and other goodies I got from you may be going in my engine soon. I'm getting closer to having everything... :D

Re: Help/recommendations for a HP 500 EFI
 

EFI motors generally need a more stable vacuum signal at low rpms because they use a map sensor to run the fuel system program. If the cam has a lower LSA like a carbed cam lets say 106 to 112 and its in a EFI motor, the idle quality and control will be a problem.

Ray @ Raylar

Re: Help/recommendations for a HP 500 EFI
 

Kinda of making it hunt around? making it rich?

I am running the 741 Crane with the 112LS . It actually idels pretty smooth. You can barley tell it from the stock cam but the Whipple could be covering it up. I am thinking the only reason I could run it up to 9.65lb boost on pump gas was because of the overlap. Had some blow thru :D


Rob :D