mercury ECU program upgrade
 

I'm looking to re-bulid my 502MPI's into a mid'ly cammed, stroked 540's. I own a 370SS Formula and I'm looking for more mid-range torque motors to pick up my cruise speed. Does anybody have a good knowledgeable ECU programer that can tweak my computers to handle the changes they would need. My stock ECU'S have already been fattened up, raised rev limiter and had all the EPA regs taken out of them by Arizona speed when I put Stainless Marine Exhaust on my stock 502's. It took Arizona a couple of try's to get my computers right. So I don't really want to use them again plus I recently read all the negative threads about that place .It sounds like they don't know what the "F" their doing out there anymore !! Who out there knows a "REALLY GOOD" computer guy that can handle my project needs ??

From what I've read, Mark at Precision Marine does very good work on retuning ECM's.

That being said, I don't think your current EFI will flow enough.

Mark at Precision was good to me when we built 540's out of my 500EFI's.
Your 502 intake's won't flow enough air to make full use of all those C.I. (my 500 intakes don't either). We did make 700/TQ full dressed on the dyno though!!!! Which brings me to my next recommendation.....don't send anyone your computers.... send them the ENTIRE ENGINE to be tuned!!!!

Eric Betty at EB Marine in Nashville reprogrammed my ECU's on my 500 efi's after the upgrades in the boat.

I've got a great engine builder already (Tony,CMS Racing, in MD) and we were planning on running the motors on the dyno. As far as the the EFI system.I was told if I mill and extrude honed the intake manifold runners to shorten the length they would give me enough airflow ? Can anybody confirm that ??

I checked on the extrude honing. Will cost you roughly 500.00 per motor/manifold and will only remove 40-50 thousands of material. That is not enough for a significant change in flow. Cutting the runners shorter might help. I am going to try that this winter and see.

I would recommend just going 30 over to 509 CI and just call Bob Madera and have custom cams made specific to your appl.

Bob is the best when it comes to the valve train of a motor. Call him at 585-654-8583

Smitty

I also agree with Griff. Mark at Precision is the best out there that I know of.

http://pmefi.com/
504.469.7463

Don't even think about going elsewhere.

Can a 502 mpi system support a 540 cu in engine,yes and no. Yes you can make decent power with the correct mods,it just won't be quite as much as if every thing was absolutely ideal. I built a 540 with a handported mpi intake with the runners cut down and a bored out throttle body,it made 657 hp at 5400/665 ft lbs of tq. The compression was only 8.3-1 and cam was a big hyd roller blower cam,with a little more compression and a little different cam the same set-up should make a little better tq and maybe a little less hp. Smitty

Call Tyler Crockett 810-531-1809. He is the man.

We're building the engines concentrating on making alot more torque . My boat is a stepped hull 14k pound 37SS Formula 10.5 beam. I'm not really concerned to much about top end. The motors my engine guy wants to build are only going to be making about 560/575 hp but alot more torque at lower (cruising) RPM then my current 502's which are making about 460hp with there upgrades which is what a boat like mine needs to get full use of the step hull and move 14k pds worth of boat at good cruising speed. I'm cruising now 43.2 mph (gps) at 4000 RPM. I'm looking for 48 to 50 mph around 3500/3800. It's night an day the way the boat performs when it's running 48/50 but in order to cruise at those speeds now I'd have to run around at 4500 which is too hard on the motors and "too" hard on the gas tanks !!!

I'm no builder but had some buddies that really hooked me up. Your right about TQ, max HP isn't what most of us need. I wanted a good cruise speed in our 382 Formula. We only made 630hp at 5,200.....but made 700 TQ at 4,300. With 5 blade props I'm now running 55-57 at 3,500!!!!! :) (best test pass of 58.5)

what did you finally end up doing to your intake manifolds to get them to flow enough air ??

I have/had 500EFI's so they already flow better than yours, but still don't flow enough. We didn't change the intakes at all. Went with ported 308 heads and the ASM monoblade throttle body to move as much air as possible. Again, all this was my builders recommendations..... Precision Marine dyno'ed these in full dress (seawater pump to wet CMI's). As I understand it, this combination resulted in lower HP than expected, but higher TQ than expected. (I had no idea what to expect).


Basic info:
540's
ported Iron Eagle heads
9.75 compression (93 octane)
ASM monoblade TB
cam a "little bigger than" the 741 crane

Tyler Crockett all the way, on a dyno fully dressed 468 ProCharged 720 HP 727 TQ

I'd suggest building those into 540s, go with a large oval port head and mild cam. You'd have real torque monsters. They'd probably lay down about 4500 RPM, but that sounds like what you are looking for. I doubt intake mods would help any in the 3500-4000 rpm range you're concentrating on. Get someone to program the ecm's in the boat. They can get the fuel curve and timing optimized for best cruise. You cannot really duplicate that on the dyno. I've been able to get significant mileage increases at cruise by tuning on the water.

Where are you located? There are several of us that can get it dialed in correctly. But you're not going to get what you are looking for by shipping the ecm off to someone unless you can provide them all the data needed to make the changes.

I'm out of Maryland. I already had a conversation with Mark at Precision. He said it sounds like I'm heading in the right direction. He suggested going with aluminum heads for better flow. He also suggested that after the motors are built ship one down to him along with both my ECU's and have him perform the dyno and calibrations. I'm tossing that idea around............

That is EXACTLY what I did 2 years go.....the man knows what he's doing!!!

You can't go wrong with Mark at Precision!!! I have a Procharged 502 down there right now. He does a great job and he has done work for people I know from all over the country. He treats his smaller lower horsepower jobs with as much care as his crazy high horsepower no expense spared jobs. I had my engine and my boat at a different shop all year but never got it right. Mark is a class act!!

http://www.donzi.net/forums/showthread.php?t=55279

who did you use for shipping ? What did it cost you ? How long did Mark have your motor ?

I can't remember for sure.....Mark probably had it 1.5-2 weeks. I own a printing company and had my shipping dept ship the motor with one of the LTL carriers we contract with.....I think it was in the $300 price range each way????