Building a 500hp 454

[Kay86K5]

Meh, I have thought about it and ran the numbers over and over and over. Everytime the numbers don't compute. The high purchase price of a diesel doesn't pay for ME with the amount that I need a diesel. Now with that my next "new" truck will be a Duramax. Because it's what I want. Not what I need. But pen to paper the cost of a conversion or the buying a new one for the average guy like me. Doesn't work. I can buy lot of 4 dollar gas for the extra money to buy a dmax.

I literally couldn't have said it better myself

These days that seems to be dwindling with the DI gas motors and the added DEF, etc.

On the way to the dunes a year or so ago when I pulled a 32 ft enclosed trailer weighing ~10k lbs with my 2016 L86 6.2L DI motor I got 9.5 MPG. My friend with his 2016 2500HD duramax pulling a 28 ft enclosed weighing about ~9k lbs got....... 9.5 mpg. Total rig weight was similar and both trailers had extra height for taller vehicles. So how much fuel did that ~$10k upgrade save him? I know I used zero DEF fluid which is probably negligible.

Granted that wasn't an old big block (nor was it an old cummins) and if you start towing over ~12-13k you kind of need the diesel. But for most of us the diesel will never pay for itself (especially at zero fuel savings) and you don't have to deal with the sticky smelly fuel pump every time you fuel up.

I love your comparison here. I had a similar comparison when I owned a 99 24v dodge last year. When I towed with it, I would get 9 mpg's. When I tow with my 8.1, I get 9 mpg's. Sure empty I get 11 with the 8.1 and the cummins empty would get 18, but I don't know about everyone else, but I never daily drove the trucks (I have a little commuter for that). So for me they only get used when I need to hook up a trailer and haul something. So mpg's don't mean a darn thing to me with these trucks. But I guess others have different opinions where they daily their truck, and drive it to the mall with the mirrors flipped out as much as possible (oh, and don't forget the bitch rims on there too). So if that's what their looking for, then yeah, the diesel empty is going to get way better mileage than a BBC empty, so go for it (). Oh, and I sold that dumb dodge as fast as I could because these idiots paid me so much freaking money for it, I couldn't say yes fast enough. And guess what I did, turned around and bought a BBC suburban for less than $3000 and pocketed $7000, bahahahahaha

I'll also note my thought to buy a dmax is because they don't make a 8.1 anymore. And finding a lower milage one has been less productive then looking for hens teeth.

If you hold off for a while longer....the rumor is GM is coming out with another BBC. The rumor is larger displacement than the 8.1 with direct injection (to compete with the new big block 7.3 gas that ford released). I know it's still rumor, but as the months go on, it's starting to sound more and more likely. I'm very interested to see if this plays out. If it does, I may break my rule of never purchasing a new truck, and actually get one. Then just plan to never sell it for as long as I live.

 

[beags86]

I literally couldn't have said it better myself



I love your comparison here. I had a similar comparison when I owned a 99 24v dodge last year. When I towed with it, I would get 9 mpg's. When I tow with my 8.1, I get 9 mpg's. Sure empty I get 11 with the 8.1 and the cummins empty would get 18, but I don't know about everyone else, but I never daily drove the trucks (I have a little commuter for that). So for me they only get used when I need to hook up a trailer and haul something. So mpg's don't mean a darn thing to me with these trucks. But I guess others have different opinions where they daily their truck, and drive it to the mall with the mirrors flipped out as much as possible (oh, and don't forget the bitch rims on there too). So if that's what their looking for, then yeah, the diesel empty is going to get way better mileage than a BBC empty, so go for it (). Oh, and I sold that dumb dodge as fast as I could because these idiots paid me so much freaking money for it, I couldn't say no fast enough. And guess what I did, turned around and bought a BBC suburban for less than $3000 and pocketed $7000, bahahahahaha



If you hold off for a while longer....the rumor is GM is coming out with another BBC. The rumor is larger displacement than the 8.1 with direct injection (to compete with the new big block 7.3 gas that ford released). I know it's still rumor, but as the months go on, it's starting to sound more and more likely. I'm very interested to see if this plays out. If it does, I may break my rule of never purchasing a new truck, and actually get one. Then just plan to never sell it for as long as I live.

I would guess it would just be a another big inch LS. I could be wrong.

 

[Kay86K5]

I would guess it would just be a another big inch LS. I could be wrong.

You very well could be correct, but a 500+ cubic inch LS sounds pretty biznitchin to me .

I would think from the factory you would be close to 450 hp and at least over 500 ft lbs (and that's held back from the factory, as that's what GM has always done with their motors), plus with direct injection and an 8 speed tranny (or whatever their putting in the newer trucks nowadays), I would think realistically you could still get in the low to mid teens on mpg's empty. For 500+" gas motor, that would be pretty freaking fantastic in my book

 

[beags86]

You very well could be correct, but a 500+ cubic inch LS sounds pretty biznitchin to me .

I would think from the factory you would be close to 450 hp and at least over 500 ft lbs (and that's held back from the factory, as that's what GM has always done with their motors), plus with direct injection and an 8 speed tranny (or whatever their putting in the newer trucks nowadays), I would think realistically you could still get in the low to mid teens on mpg's empty. For 500+" gas motor, that would be pretty freaking fantastic in my book

I guess if they wanted to bring out a 550 cube LS who would I be to judge. Lol

 

[Kay86K5]

I guess if they wanted to bring out a 550 cube LS who would I be to judge. Lol

 

[folkenheath]

I love your comparison here. I had a similar comparison when I owned a 99 24v dodge last year. When I towed with it, I would get 9 mpg's. When I tow with my 8.1, I get 9 mpg's. Sure empty I get 11 with the 8.1 and the cummins empty would get 18, but I don't know about everyone else, but I never daily drove the trucks (I have a little commuter for that). So for me they only get used when I need to hook up a trailer and haul something. So mpg's don't mean a darn thing to me with these trucks. But I guess others have different opinions where they daily their truck, and drive it to the mall with the mirrors flipped out as much as possible (oh, and don't forget the bitch rims on there too). So if that's what their looking for, then yeah, the diesel empty is going to get way better mileage than a BBC empty, so go for it (). Oh, and I sold that dumb dodge as fast as I could because these idiots paid me so much freaking money for it, I couldn't say yes fast enough. And guess what I did, turned around and bought a BBC suburban for less than $3000 and pocketed $7000, bahahahahaha

Actually my 6.2DI with the 8 speed auto averages 19 - 21 MPG without a trailer depending on what type of driving.(not city driving) Granted this is not beating on it but it does very well, I don't think an empty Dmax is going to do better, but they do weigh another 1,000 lbs or so too being the HD. Although these days the standard 1/2, 3/4, and 1 ton aren't what they used to be. My NHT 1/2 ton has a payload of over 2,000 lbs, or 1 ton. And some of the 1 tons are now over 6,000 lbs payload. So it's more like 1, 2, and 3 ton trucks these days. Granted, I did need a distribution hitch for my half ton over 7,000 lbs. But it's also a sway control hitch, so when the crosswinds hit and your driving the sail down the road that's 10 ft tall and 32 ft long that sway control was helping, because I could feel the trailer moving around and I had to slow down to about 72 MPH to be comfortable in traffic. Well, I asked my friend how his 2500HD did, and he said, "it was bad, it was changing lanes on me it was so windy!". I remember thinking, damn, it wasn't that bad and my trailer is 4 ft longer. Maybe he could use the sway hitch anyway. I've pulled 18k lbs before with a Dmax myself, but it was an open goose neck trailer, so wind wasn't an issue.

You very well could be correct, but a 500+ cubic inch LS sounds pretty biznitchin to me .

I would think from the factory you would be close to 450 hp and at least over 500 ft lbs (and that's held back from the factory, as that's what GM has always done with their motors), plus with direct injection and an 8 speed tranny (or whatever their putting in the newer trucks nowadays), I would think realistically you could still get in the low to mid teens on mpg's empty. For 500+" gas motor, that would be pretty freaking fantastic in my book

Did you see the new 6.6L DI gas motor for 2020? Its a direct injected variable valve timing LS thats 6.6L (about 400 cid), and makes 400 hp and 460 lb-ft. If you saved the 10k diesel upgrade and spent $7k on the eaton (edelbrock or magnuson, etc) supercharger you could be approaching 700 hp for less money than the diesel.

The only downfall is it comes with the 6L90, not even the 8L90 or 10 speed(in the 1/2 ton trucks) or the new HD 10 speed allison. But thats still better than the ole 4 speeds.

 

[kgblazerfive]

I really enjoyed driving my, not towing anything, 99 Burb home from Bear lake pulling the hill at like 70 mph. Passing all the cars and other trucks uphill in the passing lane.

 

[mrk5]

I was unaware big block owners thought about MPGs

...but their wives do.

Towing the camper I got about 7mpg. Only reason I was really paying attention was because the fuel stops are further apart in eastern Wyoming so when I had to switch tanks at 120 miles instead of 150 like I had anticipated I started doing the math because I was worried I'd messed up my plans.

I also ended up running different speeds and didn't see a difference in consumption. I ran as slow as 55 on one tank and as fast as 68. With the truck weighing 8000lbs, I figured the GVW with the camper all loaded up for the trip I'm around 13k.

I really think with the 4l80e I have now, I would probably be better served with slightly higher gearing; like 4.56 instead of 5.13. I'm shooting for 65mph on the highway which puts the RPMs around 2300 and I'd like that to be a little lower. There were a lot of grades that required a down shift to 3rd and the truck would get back up to 65 pretty easily but then its running 3000RPM or more until the hill finally tops out. I feel like it could still pull those grades at say 2700 or 2800 which is where it would be with 4.56 gears. Then I would be running the flats at around 2000RPM. With the Magnum box, I wouldn't be losing as much gear on the trail dropping to 4.56 gears.

This is where my thought about needing more power at 2200-2500 RPM came from. It would be great if I could pull a lot of those grades in OD running 65mph at 2300RPM if I keep the 5.13 gearing.

I've also thought about just getting another truck, like an early 2000's GM with an 8.1L or 6.0L that has AC. Hell even a Dmax truck. I could get an SAS kit from ORD and pretty much swap all the good stuff from the crew cab to that truck. But then I realize it's still cheaper to keep the 89 crew cab and hop up the motor and add aftermarket AC.

 

[kgblazerfive]

Stay away from the 6.0L.

You can convert you 454 to a 8.1L injection and ignition and stuff, or at least that is what the internet is telling me.

Why not just do a factory ish A/C set up ? Guess depending on how much the aftermarket stuff is it may not be worth it.

 

[folkenheath]

You can convert you 454 to a 8.1L injection and ignition and stuff, or at least that is what the internet is telling me.

That's what I did with the BBC in my regal, except I converted it to 10.4L before I converted it to DIS ignition with 8 coil packs.

I planted the seed in @Greg72 's might was well build to convert to DIS it works so well. (Hopefully he does it, time will tell) Mine was a Mark IV block, but if you have a Gen VI block you can buy a ~$600 kit to put cam and crank sensors in the timing cover, and then it's even easier, you just get an LS EFI system and plug everything in. You just need to swap firing order in the computer or at the wires.(or get an LS firing order cam for your big block)

 

[mrk5]

Stay away from the 6.0L.

You can convert you 454 to a 8.1L injection and ignition and stuff, or at least that is what the internet is telling me.

Why not just do a factory ish A/C set up ? Guess depending on how much the aftermarket stuff is it may not be worth it.

Mostly because it's a non-A/C cab so I figure it would be a lot of work converting it. But I really have no idea. I also thought a newer aftermarket system might be better technologically. At the very least work better with the refrigerants available today.

 

[beags86]

That's what I did with the BBC in my regal, except I converted it to 10.4L before I converted it to DIS ignition with 8 coil packs.

I planted the seed in @Greg72 's might was well build to convert to DIS it works so well. (Hopefully he does it, time will tell) Mine was a Mark IV block, but if you have a Gen VI block you can buy a ~$600 kit to put cam and crank sensors in the timing cover, and then it's even easier, you just get an LS EFI system and plug everything in. You just need to swap firing order in the computer or at the wires.(or get an LS firing order cam for your big block)

Got a link?

 

[kgblazerfive]

Mostly because it's a non-A/C cab so I figure it would be a lot of work converting it. But I really have no idea. I also thought a newer aftermarket system might be better technologically. At the very least work better with the refrigerants available today.

Having pulled apart a bunch of these and done the reverse conversion hardest part is making the hole in the firewall.

The one benefit would be the readily available stock parts for it, at least for now. The system will run fine on R134 you could even do some mods to the mod and run a compressor from a later year ie 99 or so that still uses a BBC so all the accessorizes will bolt up but you may have to get fancier and add the one belt system.

 

[mrk5]

I figure if I went that route a donor vehicle would probably make that job the easiest.

 

[beags86]

...but their wives do.

Towing the camper I got about 7mpg. Only reason I was really paying attention was because the fuel stops are further apart in eastern Wyoming so when I had to switch tanks at 120 miles instead of 150 like I had anticipated I started doing the math because I was worried I'd messed up my plans.

I also ended up running different speeds and didn't see a difference in consumption. I ran as slow as 55 on one tank and as fast as 68. With the truck weighing 8000lbs, I figured the GVW with the camper all loaded up for the trip I'm around 13k.

I really think with the 4l80e I have now, I would probably be better served with slightly higher gearing; like 4.56 instead of 5.13. I'm shooting for 65mph on the highway which puts the RPMs around 2300 and I'd like that to be a little lower. There were a lot of grades that required a down shift to 3rd and the truck would get back up to 65 pretty easily but then its running 3000RPM or more until the hill finally tops out. I feel like it could still pull those grades at say 2700 or 2800 which is where it would be with 4.56 gears. Then I would be running the flats at around 2000RPM. With the Magnum box, I wouldn't be losing as much gear on the trail dropping to 4.56 gears.

This is where my thought about needing more power at 2200-2500 RPM came from. It would be great if I could pull a lot of those grades in OD running 65mph at 2300RPM if I keep the 5.13 gearing.

I've also thought about just getting another truck, like an early 2000's GM with an 8.1L or 6.0L that has AC. Hell even a Dmax truck. I could get an SAS kit from ORD and pretty much swap all the good stuff from the crew cab to that truck. But then I realize it's still cheaper to keep the 89 crew cab and hop up the motor and add aftermarket AC.

The only time when my wife realized how shitty of gas mileage the big block was is when she had to DD it while her car was broke. We lived in DTC and she worked in Broomfield. Lol she was complaining in 2 days how she had no gas left and she just filled up. Lol.

I wouldn't change anything until you build the engine. All that may change with a new engine with a different powerband. Then afterwards you may need to change gearing.

 

[mrk5]

Yeah I was thinking the same about gear changing.

My wife was asking about mpg because I had messed up my figuring on this trip. If I had planned correctly, it wouldn't have come up.

 

[folkenheath]

Got a link?

https://www.jegs.com/i/Chevrolet-Performance/809/19260247/10002/-1

 

[sweetk30]

https://www.jegs.com/i/Chevrolet-Performance/809/19260247/10002/-1

looks like stock 8.1 parts from the stuff i have seen on 8.1

 

[folkenheath]

looks like stock 8.1 parts from the stuff i have seen on 8.1

It kinds of is except the timing cover is not the same on the 8100, I don't think the 8100 timing cover will bolt up to a Gen VI block? At least it wouldn't when my father rebuilt a couple 8100 prototypes back before they were even available in trucks. Also, the 8100 I believe had the crank sensor in the back of the block, because we used to make them at Honeywell where I used to work.

 

[ZooMad75]

Just to add on the coming big block rumor... It may not be a GM engine. Might be the psi 8.8L with di and variable timing. Which is is an newer version of the 8.1 GM sold to PSI. A version of the 8.8 is already in production and in use in school bus applications.

What I've heard is the big block won't come in any light duty truck. Strictly medium duty. The 6.6 is what we get for now. It's about as big as the gen 5 will take for bore, so stroking will be the only way they get bigger without a new design with a bigger bore spacing.

Then again this is a rumor and in 6 months to a year I might turn out to be all wet.