Daveinet wrote: Yes, this is a wine about my MPG. I did my first real mileage test with the new engine and fully calibrated MPFI. Even changed my gearing so my engine would turn 500 RPM less at cruise. Kept it under 70 mph, and tried to aim for 65 mph most of the time. This is about 5 mph slower than I normally travel. My mileage was 7.6 which is around .8 mpg less than with the old 454. I really tried to do everything right, bought an engine with a higher compression ratio, added multi-port fuel injection, lowered my gearing and some how I came out with less mileage. Doesn't really make any sense, but sure is frustrating, especially for the money and time spent. Ironically during my test runs, I used the old gear ratio and had my foot into it, cruised at much higher speed, and really didn't get any worse mileage. Grrr, not sure what else to do other than to wine about it. Yes, there is gobs of available power, but that really was supposed to enable the lower gearing, which it did, but there is no advantage.
I have been following your efforts to rebuild your coach for some time. I find it very interesting and at one time may have joined you in doing simething similar. However, old age takes it's toll and has.
I doubt that your fuel mileage will get much better - although it likely will after the engine becomes broken in better - it shouldn's take but 2 or 3 thousand to start seeing an incrimental increase though.
Maybe you should start doing some "drag" racing agains a few of these local teens - you just might smoke a few.
Just enjoy your coach - it's so good to watch someone work as hard and smart as you.
God Bless
Bill
Bill W. Trammell
Wife - Judy
2001 Monaco Dynasty Chancellor
2008 Malibu 2LT toad
Deen wrote: Wine = fermented grapes
Whine = complain
Wonder if you should throw some more money at it. Sounds like the bigger engine takes more fuel. But you'll be the first to the top of the hill, if you can make it before running out of fuel. Sometimes stuff happens. Maybe you should have gone with just a Banks SYSTEM that is already proven to work. Although, to be truthful, I'd have probably done what you did.
I think it fits more in the realm of carping... But that's really not too bad of mileage depending on driving style. I would suggest buying a vacuum gage and try driving while trying to get the highest vacuum level. You would be amazed at the mileage gain you can get...
Dave Head
Oviedo FL
95 Foretravel U320C SE
M11, HD4060
Deen wrote: Wine = fermented grapes
Whine = complain
Road Runners wrote: Should we whine about our wine. Or, should we drink the wine while be whine about our MPG.
Thanks gentlemen. I knew it was misspelled, but couldn't make it look right.
I never really thought I would recoup the cost of the engine, but it was partial justification for fuel injection.
As far as slowing down and changing driving habits, for this trip I slowed down 5 mph from how I drove with the old engine. I was not trying for some pie in the sky, but was looking for an improvement over my previous engine. Comparing the two, this one did worse under easier driving. That is really the frustrating part.
Per the comments about Banks, my current exhaust is the same with both engines. My complaint is the new engine is doing worse than the old engine. So the exhaust should not be a factor when comparing the two. Banks does not make headers that will fit my motorhome, so it is not a choice anyway. The old 454 did very well with the current exhaust, so its probably OK.
My real frustration is that compared to my old engine, I'm doing worse instead of better, even though I've so many things that should have made it better. A job worth doing is worth doing right. But did we? That is the kicker.
The other half the equation was at some point, I was planning on going to a 4L85E when my pocket book recovered. The gearing change I made last week, and now the end result suggests it may not be worth it. Incidentally, with the gearing change, I can't get rubber off the line, except on rare occasions, but that really is OK. It still has plenty of pull on hills in high gear. Now I'm wondering if I should switch it back. The one advantage of the gear change is that the cabin noise is reduced. There was a resonance that came in around 3K RPM, which now I would rarely hit. (3K would be over 80 mph) The gear change takes less than 3 hours, so it is pretty easy to do. It involves swapping the transfercase gear positions (FWD) Before the gear swap, it was a little touchy off the line. It would break loose even up to 15 mph.
* This post was
edited 06/24/08 08:05am by Daveinet *
v8q wrote: I would suggest buying a vacuum gage and try driving while trying to get the highest vacuum level. You would be amazed at the mileage gain you can get...
Actually it has a factory installed vacuum gauge, but so far, I have my laptop hooked to the ECM, so I read manifold pressure and injector pulse width. I hit a really strong headwind for about 5 miles. Really could not tell by throttle position, but I could see the treas bending over. I looked over at the pulse width, and it had jumped from ~2.3msec to over 3msec.
What about a Banks? About 3100 instaled, should get you another .8.
Systems the improve performance in general do nothing to improve mileage. Bigger engines like the 502 c.i. take more fuel to operate as they are designed for higher performance and you have to feed the ponies.
You mentioned lowering your diff. ratio, you should raise the ratio for lower RPM at a given speed as lower ratios will cause the engine to turn more RPMs at the same speed.
Slower speeds and easy acceleration are the keys to improve fuel mileage a long with lessening your GVW, i.e. lessen the overall wt. of the MH by removing those items you don't use and travel with less water/empty gray/black water tanks.
Arnie
2003 Travel Supreme MH
38KSO1 Cummins ISC 350HP
Car Dolly w/1996 Toyota RAV4 2WD
1963 Pontiac Grand Prix
Hey Dave,
As others have mentioned, I would give a try at slowing down into the 55/60 mph range if for nothing else, experimentation. See what happens there. You might find a sweet spot for that engine somewhere in there.
mtrumpet
2000 Southwind Storm 30H
Ford Triton V10 6.8L
F53 Chassis
Davis Tru-Trac
Henderson Rear Trac Bar
Carquest/Moog Steering Damper
Monroe RV Gas Magnums
Goodyear G670 RV's
I would be looking at the exhaust system, especially since you say it is the same. Maybe, there is back pressure, that is too much for the larger engine. Just a thought.
My mileage complaint is not about over all mileage, but is a complaint about the comparison from the old motor to the new. Maybe too if, once the engine is broken in, if I pick up a half mpg, I'll break just about even with the old engine.
One very interesting thing, I was going over a data sheet print out from a Desktop Dyno software analysis of this setup. It shows that air fuel mix quality does not reach 100% until the engine is turning 2500 RPM. My test cruise, the engine was below that. I wonder if that is a factor.
Nomadac wrote: You mentioned lowering your diff. ratio, you should raise the ratio for lower RPM at a given speed as lower ratios will cause the engine to turn more RPMs at the same speed.
Just for clarification, I probably stated it wrong. The engine RPM decreased by 500 RPM at 60 mph by swapping the gears in the chain case/transfercase (FWD). The gear size difference is 1.11, so the diff ratio is either multiplied or divided by 1.11, depending on which way you install the chain gears. Its a fairly easy swap.... No, there is no way I'd be changing diff gears, yikes I had the diff out once, it was not an easy task.
* This post was
edited 06/24/08 11:32am by Daveinet *
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