14 liter Series 60 in 1988 Prevost

[Hard Headed Ken]

Clifford my 8V was 475 HP DDECII and after cooled. I guessed there were several things I could have done to help the fuel mileage. I owned buses for several years with two strokes. A 4104 with a 671 then I installed a 6v92 in that and my Prevost with the 8V92. I don't why, but I just never loved them, even though that 671 was about bullet proof. The 8V in my Prevost had plenty of power and I'm reasonably sure it would out run any 4 stroke bus I've been in at least in drag race. I would not have changed it except it started leaking coolant around a liner o-ring. If I had known how many hours it was going to take to do the swap, I don't know, I'm just out of the delivery room and the birth pains are fading but I still remember the pain clearly. I say today "I'm never having sex with another bus". Check with me in a few weeks, maybe I could be persuaded.

As for the fuel mileage it will take a few fill ups and at $4 a gallon those fill ups are just about out of reach right now. I'm going to see where I am on MPG then I have one more thing to try, advancing the cam about 4 degrees. I have a friend claiming at last extra mile per gallon with that modification on trucks pulling 80,000 lbs. I'm always skeptical, but I have some experience degreeing cams and I know the general effect it's going to have and since I'm turning 1400 RPM at 70 MHPH I think it could work.

Ken

[Don Fairchild]

Ken, one of the things you will find is that the timing retard is in the camshaft profile and not the gear timing. We experimented with a couple of offset TRS sensors to try and find a better way of advancing the timing, we did make the engine run a lot better and use less fuel and also lowered the emissions but could not keep the sensor from leaking oil once we modified it. If you have a buddy that can modify the ecm you will be better off than trying to advance the camshaft. Maybe Clifford can help you a little. He does know the guru on the ecm's.

Good luck

Don

[Seangie]

Ken,

I have zero experience with buses or rebuilding engines. Seeing all the work you put into this is absolutely amazing.  What an incredible experience and payoff. Almost too much to process.

-Sean

[Hard Headed Ken]

Don,
I understand what you are saying because the cam provides the injection pressure and the ECM controls the exact injection timing. Inside the ECM program that is called the BOI table "Beginning of Injection". I can change that table, Im trying to find at what point in the stroke of the injector is there enough pressure for a correct spray pattern. Advance the timing too much and there may not be enough pressure. The injectors in this 14 liter are different from the 12.7, there is no injector height to set. Rotate the engine until the injector is at full stroke, bottom it out with the adjuster, back off ¾ of a turn and tighten the lock nut.

Sean,
Thanks for you complements. It was a challenge and I had enough experience to know better but I did it anyway. Payoff?? Maybe, hopefully I'll be able to get some use out of this in the future. One thing I just recently noticed about myself, "I can do anything but I don't know nothing". I know there is a conflict in that statement but I think it fits me.

Ken