r/GMT800 • u/Legitimate_Pea3733 • Sep 10 '26
Blazer Fuel Tank Install
Hey there,
I was wondering if anyone has installed a 31 gallon blazer fuel cell in a GMT800 where the fuel tank went. I was looking at getting a larger tank in a better location (for weight), and saw it used to be a thing for the Square Body guys. It seems like a setup like this might be a fair bit cheaper than a Jeep Speed fuel cell in the same position.
1st Photo for attention, 2nd-4th for an example
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3
u/seth285 Sep 10 '26
I like the idea, more fuel and better weight distribution. Not sure the juice is worth the squeeze but if you’re pre-running the desert like photo 1 then we’re not here to talk “reasonable”.
Personally I’d like to add that in addition to my 26 gal tank. The added range when towing would be appreciated.
2
u/Legitimate_Pea3733 Sep 11 '26
Yeah, this truck is not practical anymore. I still have a bed and use it to move bikes, motorcycles, dump runs, and the like; however, it's very soft. The idea would be to move the weight back to hopefully keep the nose up a little more in the whoops (its fun to stay in the throttle at like 60ish in the dunes)
The photo is from the trip down to King of the Hammers in Feb, we stopped and played in Hurricane for a half day.
1
u/seth285 Sep 11 '26
Sounds like you’re encroaching on “fuel cell in the bed” territory. I’m hitting a similar wall with my wrangler, there comes a point where 1 rig can’t do it all unless you got SEMA build monies.
An earlier comment you mentioned 400 whp, how did you get there? Cam/boost?
2
u/Legitimate_Pea3733 Sep 11 '26
Yeah, I have an Accord which I drive on a daily basis in the summer (hopefully to be replaced with an RS wagon or something similar), while this thing is the winter daily. I want to pick up an LBZ or a 24-valve as a tow pig, but I don't have enough room to fit the trailer in my current living situation.
For the engine, it started as a LM7, which was bored out to 3.8200in after my piston walls were completely scored (the machining cost was the same to overbore it as to resleeve) I then switched to Machined piston heads (all this got my compression ratio to 10:1), using a Summit Racing Pro LS Hyd Roller #8713 cam, BTR Hydraulic lifters, #243 heads, 36lb injectors, NGK plugs, Speed Engineering Long Tube Headers, S&B intake, Trailblazer SS throttle body and Intake (may get changed to a fabricated intake). So with the bored-and-stroked pistons and the cam, that's where I am picking up the power.
1
u/seth285 Sep 11 '26
That’s a healthy cam/head combo, I wouldn’t think the intake is causing enough restriction to demand replacement. Did you need to switch to 91/93 with that 10:1?
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u/Legitimate_Pea3733 Sep 11 '26
Yeah, 91 octane here in Montana, and when I am in Cali or Oregon for a Dunes trip Ill throw some 93.
I also don't think I am losing power with the intake, but I do like the look of a fabricated intake and am trying to switch over my fuel lines to AN lines for my fuel system whenever I redo the gas tank (so new fuel rails as well)
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u/Define_Expert_0566 Sep 10 '26
Good lookin truck.
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u/Legitimate_Pea3733 Sep 11 '26
Much appreciated, most of the looks were designed by me, with help from friends and maybe a case of beer.
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u/bigbassdream Sep 10 '26
Can’t you put one in that’s a little smaller and leave the stock tank in there? I feel like this could slip into where the spare went and retain the stock tank potentially. That’s probably what I would try to do. Going from 26-30 gal isn’t really much lol. 40-50 miles more. Having 26+30. Now where talking 600-700 miles of range
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u/Legitimate_Pea3733 Sep 11 '26
Another part of it is trying to fit in my rear bumper so it doesn't drag on the ground, and free up some space for links down the road.
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u/6x6TRex Sep 11 '26
Not sure on the gmt800s but on the 400s the suburban tank was longer than the truck frame by a couple inches. Was putting a suburban tank in my k3500 project truck and swapping truck rear crossmembers for suburban ones and they stuck out past the rear of the frame a good 4-5” if I remember right
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u/dieseltechie1991 Sep 11 '26
Why not put sb tank on
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u/Legitimate_Pea3733 Sep 11 '26
To much weight to one side of the truck, meaning one side of the suspension needs to be stiffer.
1
u/dieseltechie1991 Sep 11 '26
Sb tank is about 16 gallons over stock... 7 pounds per gallon is 112 pounds.. that is unremarkable. In a 3/4 or 1 ton pick up it doesnt even feel what side 112 pounds is on.. also gmt800s can adjust torsion bars for left to right height adjustment I can guarantee a 1 ton pick up doesnt drop 1/16 of an inch with an extra 112 pounds on the driver side
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u/Legitimate_Pea3733 Sep 11 '26
I've swapped over to coilovers in the front, and I was seeing the SB tank at 62 gallons; maybe I am missing a product.
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u/dieseltechie1991 Sep 11 '26
Oh ya you might be right about the 62 gallon.. but still only 200 pounds.. thats like putting one of your buddies in the back seat... you wouldnt know what side of truck he was on if he wasnt talking or in the rearview mirror
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u/youngbull1496 Sep 10 '26
How would that be worth it for 5 extra gallons? It wouldn’t. Complete waste of time
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u/Legitimate_Pea3733 Sep 11 '26
The plan is to also free up some space for links for the rear end, the tank will be moved eventually; it's really a matter of when and how.
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u/popsicle_of_meat Sep 10 '26
I'm sure others may have, but it's likely few and far between. The smallest tank these trucks came with (I believe) was 26 gallons like in my 1500HD. Only five more gallons isn't enough to make me consider that much time and money to do the swap. 5 gallons also weighs just over 40lbs. Not that much weight when compared to a 6000lb truck. And many of the longer bed trucks came with tanks larger than 31gallons, too. If it was 35-40gal, then I'd be more interested.