454 Mag MPI Hop-Ups - Will this work ??
08-28-2003 | 09:12 PM
#1
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454 Mag MPI Hop-Ups - Will this work ??
Okay, I'm tired of hearing that I have to ditch my fuel injection for a carb to make any real power. How about this?
-Get rid of the MPI
-Replace heads with a good set of aftermarket heads, professionally prepped, ported, etc.
-Stock compression (maybe up to 9:1)
-Whatever cam would work good with this combo and still idle well (probably no more than 610 lift) with matching lifters, springs, etc.
-Holley Commander 950 multi-port fuel injection (I don't wan't to give up the easy starts and smooth idle)
Would this work and make some serious (but reliable) power? Are there many good marine mechanics that know how to make the Holley systems work?
(Okay, before anyone mentions it, I know all about the blower option and how it's the best bang for the buck, etc., etc.)
-Get rid of the MPI
-Replace heads with a good set of aftermarket heads, professionally prepped, ported, etc.
-Stock compression (maybe up to 9:1)
-Whatever cam would work good with this combo and still idle well (probably no more than 610 lift) with matching lifters, springs, etc.
-Holley Commander 950 multi-port fuel injection (I don't wan't to give up the easy starts and smooth idle)
Would this work and make some serious (but reliable) power? Are there many good marine mechanics that know how to make the Holley systems work?
(Okay, before anyone mentions it, I know all about the blower option and how it's the best bang for the buck, etc., etc.)
08-29-2003 | 07:31 AM
#2
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Joined: Oct 2000
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From: Western Michigan
I'm not sure the Holley Commander computer program (software) is the way to go, but they have decent hard parts. I could be wrong but last time I checked into their system they had bought the old Hirel (spelling?) program for throttle body fuel injection systems that didn't work very well unless Holley has gotten all the bugs worked out of it. I heard Speed Pro has good software while using the Holley Commander hard parts, i.e. intake manifold, throttle body, fuel rails, etc. I was originally going to go with this set-up/system until I felt like I couldn't see the light at the end of the tunnel and all these people wanted BIG $$$ to set it all up and then have to rely on them for support all the time----NO WAY! I saved myself a TON of headaches and $$$ by just bolting on a carb.
Unless you have LOTS of $$$ and patience my suggestion to you is, I would either stick with the same stock fuel injection hardparts that already comes on that 502MPI engine and have the engine modified with slightly larger hyd roller cam, cut the heads .020", put a GOOD aftermarket free breathing exhaust on it like CMI elbow tops or a Stainless Marine exhaust system, K&N air filter, larger 2.25" intake valves, roller rocker arms and reprogram the computer system. Tyler Crockett did these mods on a 502MPI like you have in a nice article for HOT BOAT magazine a few years ago. I think I have heard it said that Crockett even dyno'd some of the stock Merc 502MPI's and the average he has seen is about 375hp----which is way below the advertised horsepower level that Merc claims. You will spend A LOT of money for the parts and labor for the mods I have mentioned and you may see 100hp increase according to Crockett. Or you can totally remove the fuel injection system and bolt on an intake manifold and carb set-up and make more hp for less $$$. If you were to add all the parts to that engine as I had described earlier and lose the fuel injection and go with a carb instead you will be much better off and beyond 100hp for sure. Just my .02----have fun.
Unless you have LOTS of $$$ and patience my suggestion to you is, I would either stick with the same stock fuel injection hardparts that already comes on that 502MPI engine and have the engine modified with slightly larger hyd roller cam, cut the heads .020", put a GOOD aftermarket free breathing exhaust on it like CMI elbow tops or a Stainless Marine exhaust system, K&N air filter, larger 2.25" intake valves, roller rocker arms and reprogram the computer system. Tyler Crockett did these mods on a 502MPI like you have in a nice article for HOT BOAT magazine a few years ago. I think I have heard it said that Crockett even dyno'd some of the stock Merc 502MPI's and the average he has seen is about 375hp----which is way below the advertised horsepower level that Merc claims. You will spend A LOT of money for the parts and labor for the mods I have mentioned and you may see 100hp increase according to Crockett. Or you can totally remove the fuel injection system and bolt on an intake manifold and carb set-up and make more hp for less $$$. If you were to add all the parts to that engine as I had described earlier and lose the fuel injection and go with a carb instead you will be much better off and beyond 100hp for sure. Just my .02----have fun.
08-29-2003 | 09:28 AM
#3
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Install an Edelbrock intake manifold, Performer Square Bore marine carb and Comp Cam and see how you like the way the engine runs. If you don't like it you can always switch it back and sell the parts. You won't be out anything but a few bucks and some time.
I would be willing to bet that with the right camshaft and the Edelbrock carburetor (not a Holley) you won't be switching back to the EFI anytime soon.
The Comp Cam will give you a 20 to 25 horsepower increase over the mild stock marine cam.
Good Luck
Dennis Moore
www.mooreperformance.org
I would be willing to bet that with the right camshaft and the Edelbrock carburetor (not a Holley) you won't be switching back to the EFI anytime soon.
The Comp Cam will give you a 20 to 25 horsepower increase over the mild stock marine cam.
Good Luck
Dennis Moore
www.mooreperformance.org
08-29-2003 | 09:38 AM
#4
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From: Spicewood, Texas USA
It's the 7.4L MPI system that is junk, you can get well over 500 HP with the Merc Magnum MPI system. It makes tremendous low end torque. Just set the engine up to not run much over 5000 RPM. If you want more power than that then go with aftermarket MPI or a carb. I once built a 540 with the Merc MPI. The engine ran great up to about 5000 RPM. Thinking the MPI was killing it, we switched to a Dart intake and Holley. The boat picked up maybe 1-2 MPH and about 150 RPM on top, but lost a ton of low end. Overall, it worked best with the MPI.
08-29-2003 | 03:58 PM
#5
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Originally posted by bobl
. . . you can get well over 500 HP with the Merc Magnum MPI system. It makes tremendous low end torque. Just set the engine up to not run much over 5000 RPM. If you want more power than that then go with aftermarket MPI or a carb. I once built a 540 with the Merc MPI. The engine ran great up to about 5000 RPM. Thinking the MPI was killing it, we switched to a Dart intake and Holley. The boat picked up maybe 1-2 MPH and about 150 RPM on top, but lost a ton of low end. Overall, it worked best with the MPI.
. . . you can get well over 500 HP with the Merc Magnum MPI system. It makes tremendous low end torque. Just set the engine up to not run much over 5000 RPM. If you want more power than that then go with aftermarket MPI or a carb. I once built a 540 with the Merc MPI. The engine ran great up to about 5000 RPM. Thinking the MPI was killing it, we switched to a Dart intake and Holley. The boat picked up maybe 1-2 MPH and about 150 RPM on top, but lost a ton of low end. Overall, it worked best with the MPI.
I don't mind spending some money to swap the cam, work the heads, or even replace them with better heads. I just have not heard of anyone doing that with an MPI system.
Last edited by Ric232; 08-29-2003 at 04:03 PM.
08-29-2003 | 04:00 PM
#6
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Originally posted by Dennis Moore
Install an Edelbrock intake manifold, Performer Square Bore marine carb and Comp Cam and see how you like the way the engine runs. The Comp Cam will give you a 20 to 25 horsepower increase over the mild stock marine cam.
Good Luck
Dennis Moore
www.mooreperformance.org
Install an Edelbrock intake manifold, Performer Square Bore marine carb and Comp Cam and see how you like the way the engine runs. The Comp Cam will give you a 20 to 25 horsepower increase over the mild stock marine cam.
Good Luck
Dennis Moore
www.mooreperformance.org
08-29-2003 | 05:41 PM
#7
I hate the winter!!
Joined: Jul 2001
Posts: 2,707
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From: long island, new york
Rick,
I fell your pain!! I too am in search for answers that don't seem to exist. I am always thinking of stepping up in power. The thoughts of coming up with an engine combination that works is not the problem. The thought of having the heart of the engine re-mapped by someone half across the country, with only your cam card and flow numbers to go by, is the problem. I wish that there was a system out there that we could program ourselves on our boat or dyno. To date, I have not found a system that I have seen that is tried and tested. As far as I know the best way to do this is to send the motor to someone you can trust who has the capabilty of running the motor on a dyno , monitor the EGT's and re-map the ECU accordingly. Although I have not seen him post here lately, I know of one guy here on the board who does this with success. Rod at RPM in Wisconsin. I have heard that he has a first class operation there.
I fell your pain!! I too am in search for answers that don't seem to exist. I am always thinking of stepping up in power. The thoughts of coming up with an engine combination that works is not the problem. The thought of having the heart of the engine re-mapped by someone half across the country, with only your cam card and flow numbers to go by, is the problem. I wish that there was a system out there that we could program ourselves on our boat or dyno. To date, I have not found a system that I have seen that is tried and tested. As far as I know the best way to do this is to send the motor to someone you can trust who has the capabilty of running the motor on a dyno , monitor the EGT's and re-map the ECU accordingly. Although I have not seen him post here lately, I know of one guy here on the board who does this with success. Rod at RPM in Wisconsin. I have heard that he has a first class operation there.
08-30-2003 | 09:56 PM
#8
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Posts: 1,382
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From: Spicewood, Texas USA
Ric232, yes I am the one that did the 6.2. I did not use the Holley ECU though. It was the Speedpro - FAST system with wide band 02 sensor.
The MPI on the small blocks and the 7.4 is not good to build on. The mag. engines have a decent system. Not as good as some of the aftermarkets but OK for 500-550 HP. They have 42 lb. injectors so you just need to do a mild remap on the ECU, add an adjustable fuel pressure regulator and tweak some. There are several shops that have done a lot of dyno testing on these packages. I know Tyler Crockett has a 500 HP package that he's got pretty well sorted out. There's no reason(other than cost) you couldn't switch to an aftermarket ECU and wide band 02 sensor for the merc system if you wanted to be able to program it yourself.
The MPI on the small blocks and the 7.4 is not good to build on. The mag. engines have a decent system. Not as good as some of the aftermarkets but OK for 500-550 HP. They have 42 lb. injectors so you just need to do a mild remap on the ECU, add an adjustable fuel pressure regulator and tweak some. There are several shops that have done a lot of dyno testing on these packages. I know Tyler Crockett has a 500 HP package that he's got pretty well sorted out. There's no reason(other than cost) you couldn't switch to an aftermarket ECU and wide band 02 sensor for the merc system if you wanted to be able to program it yourself.
Last edited by bobl; 08-30-2003 at 10:00 PM.
08-30-2003 | 10:31 PM
#9
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Maybe I misunderstood what you did. Was the 6.2 buildup an ECU upgrade only and not a full replacement of the EFI system? Or are you just recommending that for my application?
Would you recommend the FAST system for my application if I chose to upgrade the ECU?
Would you recommend the FAST system for my application if I chose to upgrade the ECU?
