Rick252

I've read all the pros and cons on 7.4 MPI's. Talked and recieved the specs from Procharger now for the real truth. Who has a Procharger on a 7.4 MPI ?. How long have you ran it ? Any problems ?

Rick

pantera133

I would recommend that if you wish to supercharge a 7.4, look at the whipple system. Their fuel delivery system is superior to that of pc. I had a pc on a 2000 7.4 and only got one season out of the motor before needing re-build. Not because the motor couldnt handle the power, but because the way pc set up fuel delivery by bumping up fuel pressure to compensate for not reprogramming ecu. Excess fuel in the oil, excess fuel pressure washed down cylinder walls and caused ring failure and main bearing failure. Motor was still running but there was so much backpressure in the crankcase that the dipstick would blow out of its tube during speed runs. Hindsight being what it is and having done the research after the fact, I recommend whipple ove pc.
Mark

Turbojack

Have close friend that had one for 2 seasons, ran the hell out of it. I was surprised he had no problems. He then bought another boat with twin 454 (efi -365hp) & has now run the hell out of it for 3 seasons & boat still running same top speed as when was new.

After seeing his results & reading this board, would I go with procharger on that motor? Yes!

Offshore Addiction

well as we all know they have there pros and cons,they learn as much as we do along the way,I learned most of the cons on a triple set up,right down to the boat almost burning down due to there fuel pump relays not being able to carry the amps needed and they started on fire...I would install another one if I was asked,but only with the proper work to a motor.....some motors are in better shape than others even with more hrs on them.....just my opinion.....

Turbojack

offshore-How did relay almost start on fire? When I got mine it had a 30A fuse before relay & relay was rated at 30 amps

Offshore Addiction

it didnt almost,it did....had the same fuse,thats the same question that PC had......

blown formula

Ok, here is the deal.......

PC's are great for several reasons.....
1. I have never heard of anyone blowing an outdrive using a PC !! that's because the PC builds power on the mid to high range of rpm, not coming out of the hole where maximum stress is on the drive !

2. Requires less expertise to install than whipples.

3. intercooler is more effective than Whipples cooler

4. extremely reliable

5. less stress on the engine at low boost.

6. probably 70 % of the time, the PC will not even be in boost mode in normal driving, so there is minimal additional stress on the engine.

I have owned 2 boats with PC's..... A 650hp full roller 454 with 5-7# boost, stainless marine exhaust..... great!!

Now a 312 Formula twin 454 Mag mpi with PC's......never an issue with the PC>

Now the only negative I have for PC installation is: NOT PC"S fault !!

1. AEROMOTIVE fuel pumps manufactured BEFORE May 15, 2002
used epoxy to attach the magnets in the pump. Aeromotive will rebuild any pump still in warranty for free to one with mechanically attached magnets. If not in warranty conversion is $189.00. This defect was NOT discovered until April 2002.
Be sure to install a 100 micron filter AFTER the pump to input of regulator (provided by PC>).
2. This is MANDATORY- install the regulator ON THE ENGINE!!!! Also install a mech gauge, make lines short to fuel rail from fuel reg. If the regulator is installed on a bulkhead and then fed to the fuel rail you WILL experience a rapid fluctuation 20# in fuel pressure to the rail and then engine will be starved for fuel....meltdown time!!! This is true even IF you have a Whipple !! It is the end result of Mercruiser using BATCH or BULK firing of injectors causing the fuel to "hammer" in the line because of the firing of the injectors..... this problem is unique to MPI/injected engines ONLY!!
3. The Aeromotive roblem can & will meltdown even stock engines!!! The bits of epoxy stop-up the injector screens slowly, leaning out one or more cylinders.....that's what happened to me.
.... See "it's for certain...meltdown!!".

NineLives

I have a whipple on my 1999 7.4 mpi. The install was easy and since it replaced the whole ugly stock manifold the engine looks so much better. Only downside is getting the ecu programmed correctly(in my case). Whipple will advise you to change the L-29 heads due to the "widows peak" in the chamber causing hot spots. After all was done with I swapped my heads for the older style 7.4 (peanut port, cause I got them free) and the rest of the engine is as stock as the day I bought it. Went from 61 mph on GPS to 77.4GPS and I think with a bit more tuning I can break over 80(still seems overly rich). I havent had a single problem all season and I run the boat pretty hard most of the time. No blow-by or speed loss yet. The whole install took about 8 hours including the head swap. The ecu programing was the only thing that held me up from hitting the lake as soon as it was reassembled.

On a side note, The whipple kit replaces all of the stock injectors with 6 high flow injectors. These sit before the blower and fire 3 at a time back to back. the stock setup fired 4 (left than right banks) at a time. The stock pump remains and the stock regulator gets modified(not replaced) to an adjustable type, all this is included in the kit. Modifing the regulator is the hardest part due to where it is located(under the port engine mount inside the cool fuel box). It all plugs right into the stock lines. I have no lean fuel problems with the whipple system and I was very anal about making sure of this. The whole system is a very impressive looking unit IMO.