454 Mag MPI Hop-Ups
 

For those of you with experience, what should my next move be on my 1998 Gen VI 454 Mag MPI motor? So far, I've done:

1. Gil wet exhaust
2. Vortech flame arrestor
3. ECU reprogrammed by Arizona Speed & Marine
4. Adj. Fuel Pressure Regulator (set at 48 psi)

So far, my results have been zero at WOT. The engine runs great, but no more power.

Where should I spend the next chunk of my life savings?

The following are not options:

1. Supercharger (maybe later)
2. Dry exhaust

Thanks,

perf
 

Push your timing up about 3 deg.

Hot boat has done that on every EFI test they have published. You want your WOT timing around 36 deg BTDC - maybe a little more if you run good gas. Also, IF your system is working as it should - if you have too much timing - your ECU should bake your excessive timing back - if you experience any preignition KNOCK.

My 502 seem lame last year, and in the fall I pushed the timing up the 3 deg. and this past season the boat ran better than ever before.

Good luck

MAV

Gotta Have It,

My ECU has already been remapped by ASM, so I'm not sure I'm safe increasing timing. They told me the remap is calibrated to work off of stock timing. I'm not sure I have much comfort in the knock sensor . . . they sure as hell don't work in any of the American cars I've owned.

Mav,

I'm running at 5000 - 5050 with a 1.5 gear and 23P Mirage Plus. My reprogrammed ECU increased the rev limiter, so that is not the problem. I tried running a 25P Mirage Plus but gained no speed and lost too much acceleration.

Anyone have other suggestions?

That's what I figured. A cam swap does not seem to be an effective way to go at this point.

A Procharger will work wonders on a mag engine. Just keep it at a reasonable boost, 5lbs or less. My 502 puts out 620hp with similar mods to yours and a stage 1 Procharger. There were some good deals on them in the classified section.

Scarab22 look at this one.

Re: 454 Mag MPI Hop-Ups
 

I have a 454 in my 96 27' Power Quest its heavy modded with the following

Conversion to carburetor

Dart Alumn. Cyl heads
Dart Intake manifold (hi riser)
Holly Carb
JE pistons 9:6:1 Compression
Cranks Cam Hydrolic camshaft
Hydrolic rollers and lifters
new valve covers
blue printed and balanced

Dyno at 514hp :) hehe

If you want to see pics of the engine, you can check out the pics on my website

[IMG]www.customtints.com/454/done1.JPG[/IMG]

www.customtints.com/454.done2.JPG

Re: 454 Mag MPI Hop-Ups
 

It will not allow me to edit the top message those URLS again are

www.customtints.com/454/done1.JPG

and

www.customtints.com/454/done2.JPG

hehe

Re: 454 Mag MPI Hop-Ups
 

Modifying a fuely motor has not worked too well for me.
I changed the cam, exhaust, and had some head work done.
AZ Speed re-calibrated 3 times for me and still didn't get it right.
I have been using the stock calibration and have gained about 300rpm and 4mph with the same prop. So what is that? 40-50HP?

If you want real gains N/A, modify and use a carb.
or
Buy a blower...

Good Luck,

Re: 454 Mag MPI Hop-Ups
 

I gave up on my 454 Magnum. I am building a 540 carb motor.
At least I will be able to tune this motor myself.

Re: 454 Mag MPI Hop-Ups
 

I think the upgrades didn't help because you are at the max for the components you have.

Roby

Re: 454 Mag MPI Hop-Ups
 

a used procharger or whipple with 5-6lbs of boost will make a world of diff.

Re: 454 Mag MPI Hop-Ups
 

I did all the mods you did on my 502 mag efi and I didnt really notice any difference at all. I bought a set of Lightning stainless headers and it made a world of difference. About 400 rpm. I used to run a 22 pitch bravo at 5000 rpm, now I can pull it about 5400 with a gain of 4 or 5 honest mph. It still wasn't enough so I'm putting a vortech blower on it, Im lucky enough to live 20 minutes from Az Speed and Marine, they are supposed to be the best. I should have it back any day now (its been three weeks). Back to the subject at hand, I would invest in a set a headers because they will give you some real bang for buck and it will help with any future mods. Not only that they are about 100 pounds lighter (or they seem to be) and they look cool. Try and find a used set of CMI's, Lightnings or Imco's. Dont waste your money on the cheap Eddie Marines (no offense to the guys who have them) but I think you get what you pay for.

Re: 454 Mag MPI Hop-Ups
 

This thread is depressing!

I'm at the begining of this path with a totally stock 454 Mag MPI and have been contemplating many of the mods just discussed (exhaust, cam, headwork) and would be VERY disappointed with no improvement.

It sounds as if the EFI is the limiting factor. Possibly a larger throttle body, larger injectors, some extrude honing would make a significant difference? Sombody must have had this motor on a dyno and checked the A/F ratio. Anbody have any insight?
I would hate to go back to the world of carbs.

Re: 454 Mag MPI Hop-Ups
 

The EFI is not the limiting factor. You can modify the engine in anyway you want and just like a carb upgrade will be needed an EFI upgrade will be needed. A properly set up EFI system will always be better than a properly set up carburetor any day.

As far as extrude honing Have the intake honed as smooth as possible down to the injector. From the injector on through the intake port it should have a slight texture to promote proper fuel atomization.

Roby

Re: 454 Mag MPI Hop-Ups
 

Roby,

I am puzzled by the unresponsiveness of the 454 Mag MPI. The lower HP motors usually respond very well to upgrades ... it's the already close to max motors that are more difficult (costly) to improve.

I agree 100% that EFI should produce more power while remaining more docile than a carbed engine.

What is the big restriction on these motors that is making the external mods irrelevant?

Leo

Re: 454 Mag MPI Hop-Ups
 

how do you bump up fuel presher

Re: 454 Mag MPI Hop-Ups
 

junk the factory ecm and get a motec or similar system, then you can map your ecm on a lap top computer at your house, you might call Dustin at Whipple he is great on the ecm recal.

Re: 454 Mag MPI Hop-Ups
 

I am with formulaz583 on this one...
For those of us that like to tinker or do our own work to save some money, a carb is the way to go.
I believe robyw1 has a lot of experience working with MPI systems so it is different for him.
There are some engine builders that do have dyno proven combinations that will add 80 to 100HP to a 454 or 502MPI. Problem is that they cost like $4,500 and you need to tare the engine down.
For that kind of money, you may as well buy a blower and bolt on 160HP.

Re: 454 Mag MPI Hop-Ups
 

Correct the 454 EFI engine is useless unless you go carb like i did. While the engine was out heavy mods were done I can list detail parts and include dyno plots if you want, I have 515hp not bad for a 454! The boat will cruise at about 74MPH top speed GPS. Thats as fast as some TWIN ENGINE BOATS!

Lots of love for the 454 :) hehe Now go out and start modding the thing! If you want to take another look at my pics here

www.customtints.com/454/done1.JPG