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Open Roads Forum  >  Class B - Camping Van Conversions

 > 5.7 L Chevy engine vs the 7.4L Chevy engine

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Atlee

Mechanicsville, VA

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Posted: 06/19/11 04:43am Link  |  Print  |  Notify Moderator

Anyone have any idea what the mpg penalty is between the 7.4 and 5.7 engine. I know Roadrek, for a long time, offered RT's with the 7.4L engine as an option.

I would assume a 7.4 would function better in the western mountains, but I don't live in the western mountains, and don't expect to spend a lot of time there, relatively speaking.


Erroll, Mary, Duffy the Badger Dog plus "Ollie"
"The Traveling Koala"
2012 Koala 21CS
2005 F150 Supercab 4x4, w/ 5.4L
And Equal-i-zer WDH/Sway Control

Golden_HVAC

Fulltime, CA, USA

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Posted: 06/19/11 05:31am Link  |  Print  |  Notify Moderator

Hi,

I was not aware that GMC was putting in 454 engines in the vans, at least not during 1985 - 1996. I think they did start putting the big blocks back in the vans for a while, when they put 8.1L 502" engine in the vans, same one they put in the class A motorhome chassis at that time.

With the Ford chassis, you could always get the 460" engine, and after 1996, then the V10 6.8L engine. 5.8L 351 engine was around up until 1996, then the 5.4L engine replaced that, as the standard Ford E-250/ E-350 cargo van engine.

The 350" engine always made a great choice, and I had one in my 1985 class C motorhome.

Fred.

Atlee

Mechanicsville, VA

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Posted: 06/19/11 06:15am Link  |  Print  |  Notify Moderator

Golden_HVAC wrote:

Hi,

I was not aware that GMC was putting in 454 engines in the vans, at least not during 1985 - 1996. I think they did start putting the big blocks back in the vans for a while, when they put 8.1L 502" engine in the vans, same one they put in the class A motorhome chassis at that time.

With the Ford chassis, you could always get the 460" engine, and after 1996, then the V10 6.8L engine. 5.8L 351 engine was around up until 1996, then the 5.4L engine replaced that, as the standard Ford E-250/ E-350 cargo van engine.

The 350" engine always made a great choice, and I had one in my 1985 class C motorhome.

Fred.


I'm looking at the 1997 to ca. 2002 time frame. The chevy based 200 could be had with a 7.4L engine. Sometime in early 2000's Chevy went to the 8.1 engine.

Handbasket

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Posted: 06/19/11 06:35am Link  |  Print  |  Notify Moderator

My Tiger sits higher with more frontal area & less streamlining than most B's, and it's 4x4, but the weight is close to the same. With the 8.1 & six-speed Allison, I get a bit over 13 at ~60. When I push it up to 65-70+, it drops to 12.5 or less. I have seen over 14 for one slow downhill / level trip.

Jim, "Mo' coffee!"


'06 Tiger CX 'C Minus' on a Silverado 2500HD 4x4, 8.1 & Allison (aka 'Loafer's Glory')

VintageRacer

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Posted: 06/19/11 06:00am Link  |  Print  |  Notify Moderator

Not an exact comparison but I used to tow with a pickup with a 5.7 (a 1996 as I recall), and got around 11 mpg. My buddy towed with the same truck but the 454 and got between 6 and 7 mpg. He loved it, but then he could afford it too...

Brian


2005 F250 Supercab, Powerstroke, 5 speed automatic, 3.73 gears.
20 ft race car hauler, Lola T440 Formula Ford, NTM MK4 Sports Racer
1980 MCI MC-5C highway coach conversion
2004 Travelhawk 8' Truck Camper

McK

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Posted: 06/19/11 08:07am Link  |  Print  |  Notify Moderator

I have a 454 TBI in my '96 Chevy 3500 flatbed truck. It gets 8 mph when not towing or carrying a load. That's why I only drive it when I really, really need it. I put only a 1000 miles on it last year.


Robert
2006 Sportsmobile Sprinter


Gene in NE

Omaha

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Posted: 06/19/11 08:36pm Link  |  Print  |  Notify Moderator

Atlee wrote:

Anyone have any idea what the mpg penalty is between the 7.4 and 5.7 engine....
Rather difficult to provide you with an exact comparison, but poster "Daniel C." in this posting B+ Motorhomes indicates his 2002 Chevy van has a 7.4 L engine. In this posting a few postings later, he claims to be getting 10 miles per gallon.

I own an identical RV unit only with the 5.7 L engine. I am averaging 12.1 mile per gallon. The 2.1 MPG difference could be attributed to driving style and roads traveled.


2002 Trail-Lite Model 211-S w/5.7 Chevy (click View Profile)
Gene

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Posted: 06/20/11 03:01pm Link  |  Print  |  Notify Moderator

Atlee wrote:

Anyone have any idea what the mpg penalty is between the 7.4 and 5.7 engine. I know Roadrek, for a long time, offered RT's with the 7.4L engine as an option.


Can not speak for the 7.4L but I have been driving a 5.7L Chevy 190P for over six years. When lightly loaded I have gotten up to 17.4MPG driving across AZ, NM and TX. Loaded with a weight of about 9,000 lbs driving the mountains in CA I get about 14.6 to 15.4MPG.

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Open Roads Forum  >  Class B - Camping Van Conversions

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