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454 vs. 402 vs. LT1 Opinions?

Gorillajeep

Gorillajeep

1/2 ton status
Joined
Sep 7, 2006
Posts
240
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Location
Myrtle Beach, SC
Here is what I have. I have three options on what to do with my Burban.
'86 Chevy Suburban, 4" lift, 4.56 gears, 700r4. I love this truck and I am gonna keep it regardless. I have thought about possibly diesel too. . . . but know nothing about were to start with the diesel, and I have the three gas motors now. . . . Anyway. . . . I know the tranny will need to be replaced or seriously upgraded. I just want to focus on the motors.

What do you guys think would be the best all around option? I may be asking to much of a 25 year old truck. . . but I want it to be a jack of all trades, light wheeling, comfortable roomy road trips, tow rig for my K-5 from time to time,

The 454 (currently in the Suburban)
'87 454 that has been switched to a carb. It runs pretty well but it's a thirsty piggy. I am guessing about 8 to 10 miles to the gallon on a good day. I don't want to have to take out a loan to toss the kids in it and take a 8 plus hour road trip. Tow's the K-5 pretty well, but not like the 402.
If it's at all possible to get this motor in the mid to high teens what is it gonna take? Also it doesn't like the heat, when I am running it on hot days it acts like it's not getting enough gas. Possible evap. problem?

The 402 (needing machine work sitting in the shop)
It was a '70 402. Had a matching carb, intake, cam kit from Eledbrock on it. It ran great until it had a serious mechanical failure. (not sure what happened, kinda scared to look) It was getting in the high teen fuel mileage wise though.( I could live with) Towed the K5 a few times like a champ! The ports on the head are huge compared to the 454.
Down side it's gonna cost me to fix it. Machine work for sure.

The LT1 (sitting in the shop on motor stand)
It's a 90's some motor out of a police interceptor. Ran great not sure on gas mileage was in a buddies truck but did not seam to be half as thirsty as the BB's ran really strong. Already has multi port FI.
Down side has about 100k police interceptor miles on it. Will probably need a rebuild to be a good reliable motor for years of service.

What do you guys think? If possible give your opinion and why. Thanks.
James

2011-03-23 18.11.50.jpg
 
mid to high teens,, I personally don't think it's ever gonna happen without the Diesel. My Burb with a fresh 350tbi and new trans, 4" lift, 35" tires and 4.10's will only get MAYBE 14 or so on the freeway, that's being lucky though. Usually around the 12-13 with normal driving around town with a very light foot.

the '05 Avalanche I have here now, according to the computer is only averaging 15.2, it's mostly city driving though and has a 5.3 in it.
 
Out of the 3 engine choices you have and considering that you tow with this burb....

The 454. It's already in there. You want better mileage? Make it fuel injected. But, you won't see high teens. Low to mid teens at best.

The 402... not much to gain over the 454.

The LT1... you'll hate it. Especially towing a K5. Again, mid teens at best.

Or you could just go crazy, sell all three of those engines, and swap in a 6.0 from a newer truck.
 
Just keep in mind, you won't see high teens from a 6.0 either. But will be better than any of the other 3 choices, all around, for how you use the truck.

Seat of the pants big block feel with small block mileage would be one way to describe it.
 
You would see mid teens I bet with the LT1

If you want high teens, think about a turbocharged 6.2, still won't tow like the big block but pretty close

for a bolt in.

If you want high teens and still want it to tow awesome than look at a cummins swap
 
I few years back, when Shawn (supersize) still used his 2wd work truck,with the 6.0ltr (when it was still 2wd) as a tow rig, I was amazed at the power that thing had, We had stopped side by side at a stoplight on the way to a trail run, I was in my Burb, by myself, just the truck, he was pulling his then trail truck on a trailer, his truck out accelerated mine like I was in a little 4 banger racing a street/strip type car, and I WAS trying to keep up with him...

blew me away...
 
lt1 is a p.i.t.a to install also . every thing specific to lt1 and to fit in truck not easy job. and opti spark in front for offroad and water = bad idea.
 
Estimate your MPG with your motor choices, then plug in the mpg numbers here and see how much money you'll save on gas.
Then factor in the cost of the 6.0 swap, and decide if it is worth the swap costs.
http://www.fueleconomy.gov/feg/savemoney.shtml

I was really contemplating a 6.0/4l80e swap to replace my 454/TH400. Even at 4mpg more I don't think it would have been worth it after all swap costs were considered, plus downtime and whatever expected or unexpected problems are encountered. With my 39" TSL's I don't think there is much fuel economy potential. I think a diesel would be the only way to get some good mpg (relatively speaking) but that comes with a price tag.
Keep us posted what you decide and why.
 
Whatever engine you decide on, needs an overdrive behind it. That's where you will gain the most mileage without a Cummins swap. Even a Cummins needs the overdrive.

That's would I would consider before an engine swap.

There are some things you could do to add a little mileage to the 454. But it will still be a 454

sell the 402. Worthless for your situation. I would build a 383 striker instead and save a hundred pounds

no on the lt1 for the same reasons sweetk30 said
 
sweetk30 said:
lt1 is a p.i.t.a to install also . every thing specific to lt1 and to fit in truck not easy job. and opti spark in front for offroad and water = bad idea.
Click to expand...

Yea that opti spark does not like water what so ever. Not a cheap fix and definitely not something you want to do out on the trail.
 
RollinKaos said:
Yea that opti spark does not like water what so ever. Not a cheap fix and definitely not something you want to do out on the trail.
Click to expand...

Not to mention a power steering pump that is definitely meant for a car.

I daily drive an LT1 and it's awesome, great power and economy (with a 6 speed anyway). I wouldn't consider one for a truck, really just based on the weak PS pump and water failure prone electronics.

I like my 383 lots too, but I built that when the 5.3L's and 6.0L's were still only in brand new trucks. Today, I'd run with a take out LS motor no question.
 
How about a later 8.1 with EFI...if your gonna get louy mileage anyway,you may as well have 500 cubes to feed!...
 
I would opt for the 6.0/4L80 combo. Deals can be had. Maybe swapped in a little bigger cam for more towing power and you're set. For the price of a good rebuild on the 454 you would be better off with the newer 6.0. Towing with the 454, I'm sure the mpg numbers are low teens at best
 
Wow, you guys are really just a plethora of information. It really is a great old Suburban (and my first) It was a show rig back in it's hay day. The interior has all been redone too. It was a forestry service truck so bare bones, but I like that. It has the "dealer installed" AC on it, kind strange looking. I added the orange flames to beak up the Green a little. The first thing I thought when I got it was it kinda "looks like" an ORD truck.

Thank you Ned for the link.

I added a few pic's of the interior.

The LT1 is out, maybe save that for something else. I have some ideas for it though.

P1020432 (Small).JPG

P1020433 (Small).JPG
 
I have gotten so lazy in my older age, I can't handle driving a vehicle without power windows anymore.. :D :doah:
 
diesel4me said:
How about a later 8.1 with EFI...if your gonna get louy mileage anyway,you may as well have 500 cubes to feed!...
Click to expand...

I had an 04 2500HD with the 8.1 in it (hence my screen name). At best it could muster 12mpgs with an ext cab short bed pick up. And most of the time it was unloaded just driving to/from work. But damn that thing could tow effortlessly.

Estimate your MPG with your motor choices, then plug in the mpg numbers here and see how much money you'll save on gas.
Then factor in the cost of the 6.0 swap, and decide if it is worth the swap costs.
http://www.fueleconomy.gov/feg/savemoney.shtml

I was really contemplating a 6.0/4l80e swap to replace my 454/TH400. Even at 4mpg more I don't think it would have been worth it after all swap costs were considered, plus downtime and whatever expected or unexpected problems are encountered. With my 39" TSL's I don't think there is much fuel economy potential. I think a diesel would be the only way to get some good mpg (relatively speaking) but that comes with a price tag.
Keep us posted what you decide and why.
Click to expand...

And with an LS swap, I would never swap one in place of a good working engine based on mileage gains alone. Other factors all add up to make it worthwhile. For me, the truck would need an engine replacement to begin with. After that, the power and driveability and the increased mileage potential all add up to make it worth doing.
 
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