Skip to main content
Topic: 86 GV 454 Chevy Gas Mileage (Read 1076 times) previous topic - next topic

86 GV 454 Chevy Gas Mileage

We have just returned from a 2000 mile round trip holiday journey to the Hill Country of Texas..  first time we were able to get an accurate reading of our gas mileage based on speed and RPM's....    at 68-70 mph ( 3100 rpm) just a 6mpg... but at 64-66mph ( 2800-3000 rpm)  we bumped up to 7.5...  what a difference.. no tow vehicle.  Just half tank of fresh water on board for the 18 hours each way from Boulder CO to nearby Fredericksburg TX. 

Lost an alternator and a battery on this trip.    The Ford pick up external regulator for the original equipment alternator ( 1971 Chevy) overheated one of the 4 connections and failed...  and let the alternator speed and lock up the bearings...  stuck in Winters Texas on Sunday evening at truck stop.  monday 7am CarQuest autoparts and nearby truck and auto shop came to our rescue and replaced on site.... a few hours after breakfast and on our way home....  replaced with the upgraded ONE wire alternator and by passed the old regulator .. replaced the now dead Interstate battery and all good for the remaining 13 hours home to Boulder. 
1986 Grand Villa, 454 Chevrolet, 33 SBI tag axle
Build # 2658
2nd owner, original owner was Newman/Freeman Racing, racer Bill Freeman and actor/racer Paul Newman

Re: 86 GV 454 Chevy Gas Mileage

Reply #1
Do you have a DIODE-BASED ISOLATOR?

If so, the "one wire" will not get adequate voltage to the batteries.

What is voltage at the batteries with  the engine running-- say around 1,200 RPM?
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 86 GV 454 Chevy Gas Mileage

Reply #2
Do you have a DIODE-BASED ISOLATOR?

If so, the "one wire" will not get adequate voltage to the batteries.

What is voltage at the batteries with  the engine running-- say around 1,200 RPM?

12.5 at idle ( 600 rpm) and 13.5 - 14 at high rpm highway speed.    Not sure about the Diode...  i will do some homework.  We are at 3000 rpm's for 65 mph...  much higher than all of the FT diesels... 
1986 Grand Villa, 454 Chevrolet, 33 SBI tag axle
Build # 2658
2nd owner, original owner was Newman/Freeman Racing, racer Bill Freeman and actor/racer Paul Newman

Re: 86 GV 454 Chevy Gas Mileage

Reply #3
13.5- 14 is just fine.  No need to dig further.

Sounds like you do not have a diode-based isolator as found on most Foretravels.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 86 GV 454 Chevy Gas Mileage

Reply #4
13.5- 14 is just fine.  No need to dig further.

Sounds like you do not have a diode-based isolator as found on most Foretravels.

We are finding that we like the uncomplicated early versions of FT....  a Chevy engine you can find replacement parts in a CarQuest store in a 2100 population Texas town...  no HD consumer electronics on board...  we seem to be driving a big old Chevy truck with no flash and glam...  thanks Brett for the follow up... i will dig a little bit for my own knowledge..
1986 Grand Villa, 454 Chevrolet, 33 SBI tag axle
Build # 2658
2nd owner, original owner was Newman/Freeman Racing, racer Bill Freeman and actor/racer Paul Newman

Re: 86 GV 454 Chevy Gas Mileage

Reply #5
I've seen more than one 454 get 4 mpg in a pick up truck and I was buying the gas.. I've had a couple mh owners quote 10 mpg with that engine and my reply was ,if it makes you feel better believing that then good for you. If I were you I would be pleased with the 6.
Dub McBride 1996 270

Re: 86 GV 454 Chevy Gas Mileage

Reply #6
I've seen more than one 454 get 4 mpg in a pick up truck and I was buying the gas.. I've had a couple mh owners quote 10 mpg with that engine and my reply was ,if it makes you feel better believing that then good for you. If I were you I would be pleased with the 6.

LOL.... i cant imagine getting 10mpg...  what we did find over the last 2000 miler trip that ended yesterday that if i backed off the pedal and let it cruise at 65ish... and not charge up the rolling hills of Texas i could get the most efficient mpg... the last segment ( 7.5 mpg) from Lubbock to Colorado Springs was " uphill" referring to the altitude change to 5000 ft altitude

1986 Grand Villa, 454 Chevrolet, 33 SBI tag axle
Build # 2658
2nd owner, original owner was Newman/Freeman Racing, racer Bill Freeman and actor/racer Paul Newman

Re: 86 GV 454 Chevy Gas Mileage

Reply #7
I was a Chevy dealer truck manager 40 years ago and remember ordering a one ton 454 4x4 truck for a construction company.  Low geared tow setup,

Took  it for a drive before delivery.  OMG fast.

Had a buddy take out a vette to run with it.  Truck was as fast,

Guy later told me it was the fastest truck he had ever driven,  4-5 mpg
"Riding and rejoicing"
Bob & Susan
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: 86 GV 454 Chevy Gas Mileage

Reply #8
My friend lent me his 90's, four door 4X4 stick Chevy 454 dully for a week. He told me it got like 14 MPG. I laughed.
I went through 2 tank fulls with it. I was shocked, it got 15 MPG, I didn't baby it either
My 1990 2 wheel drive with it's fresh 454 (RV cam), throttle body injected, auto, gets easy 10-12 empty. But it's got 3:90 gears.
Chris
Chris and Tammy White  CDA Idaho
Previous owners 1997 U295 36' 3126 Cat 300 HP Build # 4998
Former Foretravel tech & RVIA certified tech
Former owner Custom Satellite home/RV satellites 
Former owner Vans LTD  van conversions
Unemployed, panhandler, drag racer NHRA #6348

Re: 86 GV 454 Chevy Gas Mileage

Reply #9
My friend lent me his 90's, four door 4X4 stick Chevy 454 dully for a week. He told me it got like 14 MPG. I laughed.
I went through 2 tank fulls with it. I was shocked, it got 15 MPG, I didn't baby it either
My 1990 2 wheel drive with it's fresh 454 (RV cam), throttle body injected, auto, gets easy 10-12 empty. But it's got 3:90 gears.
Chris
My only experience with the 454 was with a 4 bl carb.. I'm sure not saying I wouldn't buy a 454 because I would have a 70 Chevelle or Vette gladly with 454. I wouldn't give a rip what it got for mpg. I always liked the 396, 427, 454.
Dub McBride 1996 270

Re: 86 GV 454 Chevy Gas Mileage

Reply #10
My only experience with the 454 was with a 4 bl carb.. I'm sure not saying I wouldn't buy a 454 because I would have a 70 Chevelle or Vette gladly with 454. I wouldn't give a rip what it got for mpg. I always liked the 396, 427, 454.


Nice..  one of the reasons we chose our 86 454 Front Engine Gas coach was the entry price.. we are not fulltimers and we are not crisscrossing the US putting thousands of miles on our new to us coach...

We like the fact we can readily get parts when the time comes....  point of fact.  We had a external regulator fail and subsequent alternator.    Stuck overnight in a 2100 person small texas farm town .... at 7am we purchased a replacement Alterntor from the local CarQuest Auto Parts store and a local truck/auto tech installed by 10am and on the road we went...

6-8 mpg for our coach sounds much better when you can find Chevy parts and keep going on our trip... versus NO mpg because your stuck in a highly complicated diesel bus coach...

LOL

1986 Grand Villa, 454 Chevrolet, 33 SBI tag axle
Build # 2658
2nd owner, original owner was Newman/Freeman Racing, racer Bill Freeman and actor/racer Paul Newman

Re: 86 GV 454 Chevy Gas Mileage

Reply #11
If you keep it at 63  or lower you can get almost 8 in flatlands. Drag squares vs velocity.
  Those  went through fuel filtrs and  alternator belts. And exhaust manifolds. And front airbags.
 Still a cool cruiser , use it up.

Re: 86 GV 454 Chevy Gas Mileage

Reply #12
Our old SOB had a Dodge 440 and with the Carter AFB, got only 4 mpg after we bought it but improved to about 5.5 after the AFB was fixed. The change to a 7.3 turbo diesel and manual trans almost doubled the MPG. The rear axle ratio was pretty short so even with the overdrive 5th, it still turned lot of revs on the highway.

You make a good point about the ease of maintenance with the 454 as you can find used engines most anywhere and an overhaul is relatively cheap. The front engine keeps the engine compartment clean and it's pretty easy to replace simple items like water pumps, alternators, etc.

Your fuel mileage is excellent and when you consider the cost of diesel today, especially in California where it's about $4.00/gal, any advantage in diesel engine mileage is partially offset in the cost of the fuel.

For more reliability and better mileage, a DIYer could install a truck 5 speed manual transmission. It made a big difference in ours.

Mercedes has done a great job through the years with their front engined vans with the Sprinter taking the honors today.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: 86 GV 454 Chevy Gas Mileage

Reply #13
Our old SOB had a Dodge 440 and with the Carter AFB, got only 4 mpg after we bought it but improved to about 5.5 after the AFB was fixed. The change to a 7.3 turbo diesel and manual trans almost doubled the MPG. The rear axle ratio was pretty short so even with the overdrive 5th, it still turned lot of revs on the highway.

You make a good point about the ease of maintenance with the 454 as you can find used engines most anywhere and an overhaul is relatively cheap. The front engine keeps the engine compartment clean and it's pretty easy to replace simple items like water pumps, alternators, etc.

Your fuel mileage is excellent and when you consider the cost of diesel today, especially in California where it's about $4.00/gal, any advantage in diesel engine mileage is partially offset in the cost of the fuel.

For more reliability and better mileage, a DIYer could install a truck 5 speed manual transmission. It made a big difference in ours.

Mercedes has done a great job through the years with their front engined vans with the Sprinter taking the honors today.

Pierce

We found the GasBuddy app and used the searches for gas in Lubbock, Amariilo, Fredericksburg Tx and Colorado Springs.... we paid a low of 1.99 up to 2.59 along the way....  Diesel was always 3.19 and more...
1986 Grand Villa, 454 Chevrolet, 33 SBI tag axle
Build # 2658
2nd owner, original owner was Newman/Freeman Racing, racer Bill Freeman and actor/racer Paul Newman