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502 FI bigblock

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prairie

1/2 ton status
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Found an 91 Suburban for sale, 502 FI bigblock, one ton overdrive tranny, 3/4ton 4x4, diff gears?. Supposedly only 86k original miles.
What tranny should this have?
What kind of gas mileage could this possibly get? Guy says 13 mph on highway/interstate.
Need something for a grocery getter, Girl/Boy Scout bus, and ocassionally hauling loads in back or on a car trailer.
 
As in a 502 Ramjet??

A '91 could possible have a stock 4l80e, but I would bet it didn't. Most likely had the 4l60(700r4). If it truely has a "one ton" OD trans it would be the 4l80e. If the P.O. swaped in a 502 I would not be supprised if he swapped the trans too.
 
If it is a stock 3/4 ton burb that is a 1991, then it would have the heavier 4L80E trans from the factory. Sounds like a stock burb, except for a 502 that was swapped in. Gears are either 4.10's or 3.73's if they are also still original.

13mpg sounds a little high for a motor like that, but I guess if it had no lift, stock tires, 3.73's, and 60-65mph, it could be possible I guess.
 
My 95 K2500 originally came with a TBI 454. A little smaller than that 502 you're looking at, but I could get 14-15mpg on the highway. I took several cross country trips in it before I swapped the cummins in, and I would check the mileage every time I filled up. I figured it by hand, so I know it was accurate.

It had 4.10 gears and 315/75 tires and a 4L80e.
 
prairie said:
Found an 91 Suburban for sale, 502 FI bigblock, one ton overdrive tranny, 3/4ton 4x4, diff gears?. Supposedly only 86k original miles.
What tranny should this have?
What kind of gas mileage could this possibly get? Guy says 13 mph on highway/interstate.
Need something for a grocery getter, Girl/Boy Scout bus, and ocassionally hauling loads in back or on a car trailer.
Click to expand...
Get the VIN from the Sub.

If its a V2500 rig, it'll be the factory 4L80E tranny.

The stock V1500 will have the 4L60 tranny and 10 bolt axles.

Always go by the VIN and the RPO sticker to decode a truck.
 
Also, if the fuel injection is not a ramjet style I would make him prove (ie; receipt) it's a 502. If a selling point is the 502 then he's got to prove it since it would never have come in the truck from the factory.
 
You guys ever hear of the early 502s what looked just like 454's. They had the
Big plugs in the heads, like the older big blocks
 
t0mills said:
My 95 K2500 originally came with a TBI 454. A little smaller than that 502 you're looking at, but I could get 14-15mpg on the highway. I took several cross country trips in it before I swapped the cummins in, and I would check the mileage every time I filled up. I figured it by hand, so I know it was accurate.

It had 4.10 gears and 315/75 tires and a 4L80e.
Click to expand...
With absolutely crazy-ideal conditions that might be possible, but there's no way that's a normal/average reading. I've got a '94 K2500 Burb, TBI 454, 4.10 gears, 4L80E with lots of cross-country highway miles. I could get around 12MPG unladen on a normal non-windy day with no significant grades. I've talked to plenty of other FI big-block owners, and my numbers fit right in with theirs.

Did you re-pin your DRAC for the 315/75-16 tires?
 
63chevyll said:
You guys ever hear of the early 502s what looked just like 454's. They had the
Big plugs in the heads, like the older big blocks
Click to expand...

rjfguitar said:
Huh?
Click to expand...

longbedder said:
Uh, no.
Click to expand...

63chevyll said:
Crate engines only,
I have a friend who bought on in the early to late 90's and put it in his street
Rod.

I think the 1st style 502s were 454 replacements. I spose someone could have
Put one in a tbi truck as a replacement
Click to expand...
I was waiting for others to comment about this "early 502" comment.

The only 502's I know of from earlier years were probably the bored and stroked engines. The true 502 crate didn't come out until when, early 2000's? Its the Mark V and VI generation so I know for sure they never had them back in the earlier generations. At least not in a crate form that came out as a brand new engine like from GM Performance Parts.
 
63chevyll said:
You guys ever hear of the early 502s what looked just like 454's. They had the
Big plugs in the heads, like the older big blocks
Click to expand...
I wonder if you may be confused for the tall-deck motors of which the bigger trucks got back in the day?
 
thatK30guy said:
I was waiting for others to comment about this "early 502" comment.

The only 502's I know of from earlier years were probably the bored and stroked engines. The true 502 crate didn't come out until when, early 2000's? Its the Mark V and VI generation so I know for sure they never had them back in the earlier generations. At least not in a crate form that came out as a brand new engine like from GM Performance Parts.
Click to expand...


what he said... :waytogo:

the marine industry has always been an easy watch for this stuff... for as sucky as my job is, I guess thats one aspect that rocks... I play with V8 Cheby stuff all day and don't work on 4 banger minivans! :eek1::doah::waytogo::haha:


any 502 that's pre "crate 502" is not factory.... a hotrodded 454...

I remember how surprised I was when they came out with the 496.... the 502's had been such excellent performers, I thought "why change?"
 
The 502 chevy was first used in motorhomes and then later became a GM Performance crate engine. I don't know the exact year the 502 was being used in the motorhomes but it was long before 2000.
 
thatK30guy said:
I was waiting for others to comment about this "early 502" comment.

The only 502's I know of from earlier years were probably the bored and stroked engines. The true 502 crate didn't come out until when, early 2000's? Its the Mark V and VI generation so I know for sure they never had them back in the earlier generations. At least not in a crate form that came out as a brand new engine like from GM Performance Parts.
Click to expand...

hey K30, I know of one being bought in 97 as a GM crate, and another from GM before that, maybe it was a tall deck, ill have to ask, i think they both still have them, well the one is still in my friends street rod

found this, not sure how accurate it is but here ya go, i found it intereseting

"Beginning in the late-1970s Chevrolet brought out the 502 V-8. Its job was not to be used as a performance engine but as a workhorse. It was placed in fleet vehicles, such as large trucks and vans, and some police cruisers like California Highway Patrol chase vehicles. These engines stayed under the radar, but quickly garnered the attention of performance auto customizers who saw the 502 as the ultimate street fighting powerhouse. Production of the factory 502 ended in 1995."
 
longbedder said:
With absolutely crazy-ideal conditions that might be possible, but there's no way that's a normal/average reading. I've got a '94 K2500 Burb, TBI 454, 4.10 gears, 4L80E with lots of cross-country highway miles. I could get around 12MPG unladen on a normal non-windy day with no significant grades. I've talked to plenty of other FI big-block owners, and my numbers fit right in with theirs.

Did you re-pin your DRAC for the 315/75-16 tires?
Click to expand...


That's not what my everyday average was. Around town I would get between 10-12mpg.

I never changed anything for the speedometer, but that wasn't used for my mileage calculations. The speedometer was off (slow), and I always used my Garmin. If it wasn't accurate, then I don't know what is...

Mods done to it when it was still a 454:

Intake
Flowmaster
Good tune up

Engine ran like a top. Sold it to a local guy after I swapped in the 6bt, who wanted to build it up for his 70s model chevy. Engine shop tore it down, and said everything looked like it was new. It had almost 200k on it.


IIRC, 1995 was the last year for the TBI 454, and I believe it used a high pressure fuel system, similar in PSI to the vortec motors? Could be talking out of my rear, but maybe that had something to do with the bit better mileage?

Either way, the 6bt was a huge improvement in both power and mileage. I drove from home (northwest arkansas) to New Orleans, to Pensacola and part way back home before having to refuel. I could also easily make it from home to Vail on a tank, and did so twice before I sold it.
 
t0mills said:
That's not what my everyday average was. Around town I would get between 10-12mpg.

I never changed anything for the speedometer, but that wasn't used for my mileage calculations. The speedometer was off (slow), and I always used my Garmin. If it wasn't accurate, then I don't know what is...

Mods done to it when it was still a 454:

Intake
Flowmaster
Good tune up

Engine ran like a top. Sold it to a local guy after I swapped in the 6bt, who wanted to build it up for his 70s model chevy. Engine shop tore it down, and said everything looked like it was new. It had almost 200k on it.


IIRC, 1995 was the last year for the TBI 454, and I believe it used a high pressure fuel system, similar in PSI to the vortec motors? Could be talking out of my rear, but maybe that had something to do with the bit better mileage?

Either way, the 6bt was a huge improvement in both power and mileage. I drove from home (northwest arkansas) to New Orleans, to Pensacola and part way back home before having to refuel. I could also easily make it from home to Vail on a tank, and did so twice before I sold it.
Click to expand...
Interesting.

My engine runs like a top as well, and has a Whipple supercharger on it. As part of that package, it received a HP fuel pump (OEM from a 'Vette). It went from about 10-11 highway MPG to 12-13 with the blower.

Funny thing, I've got a 12V Cummins sitting in my garage that's going in the Burb :waytogo:
 
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