454 build for towing

[coolchevy]

after 200.000 mls it is time to rebuild my 454 TBI engine. At same time I will get rid of that crappy TBI setup and change to a full sequentiell EFI using Vortec parts, distributorless ignition with coils and PCM from a LS1 which I can easily programm myself to my liking.

I need torque not hp for my heavy race trailer and if mileage increases at same time even better.

in stock trim it only got 8.5:1 CR and measly peanut port oval heads with need refreshing.

I have 10.4:1 Icon piston lieing around, one of Mikes torque cams and a used but OK set of oval ort Procomp with 300cc runners here. I know about Procomp, but that ain't a race car just to get the race car from A to B and they don't cost me anything. Can't be worse then the peanut heads either. The idea was to add a Edelbrock Pro flow-X intake in combination with an LS1 throttle body. Not sure about headers if they would gain me something or not. Will still run on out lowest octane fuel with is 95 octane (about 91 your rating)

would that be an OK setup for towing or are heads to big ? I really don't want to throw too much money on those peanut port heads as there are no intakes which match.

[Alan Roehrich]

You'll find that a tow vehicle will be at least as likely to have the valve seats fall out of a set of heads as a boat is, and a lot of people had valve seats coming out of those heads on boats. It's a tow vehicle, you spend enough time working on what you tow with it, the last thing you need to spend time and money on is the tow vehicle. I'd be looking at a set of the 100cc chamber Edelbrock oval port heads if it were me.

Headers and a good exhaust system will be a big help.

Honestly, I think you'd be better off stroking it, and using a good rotating assembly with a set of pistons that take really low drag rings. That's where you'll see the most torque gained, and that will allow you to use a higher gear to keep the RPM down, and keep the throttle closed further, the two best ways to keep fuel consumption down.

[coolchevy]

points well taken. If I use those pistons I can't use the Edelbrock heads as compression will be way to high. Will look into other heads choices then.

what do you consider a good compression ratio for a towing engine anyway? I mean higher then the piss pour 8.5.1 ? how far would you go?

I do have the 4l80e 4 speed, that already helps a lot keeping rpm down. I am around 2200 rpm @ 70mph towing speed which is pushing the legal limits already a bit. Germany 68mph, Austria 50mph

[Alan Roehrich]

points well taken. If I use those pistons I can't use the Edelbrock heads as compression will be way to high. Will look into other heads choices then.

what do you consider a good compression ratio for a towing engine anyway? I mean higher then the piss pour 8.5.1 ? how far would you go?

I do have the 4l80e 4 speed, that already helps a lot keeping rpm down. I am around 2200 rpm @ 70mph towing speed which is pushing the legal limits already a bit. Germany 68mph, Austria 50mph

With EFI, you can push the limits on compression. If you use a closed or semi closed chamber with a flat top piston and a tight deck clearance that will make it even better.

Figure the compression ratio on a flat top 4.310" bore 4.50" stroke engine with a 110cc chamber, 0.0" deck height, and a 0.042" x 4.350" bore head gasket. I'm thinking it's about 9.7:1. That would be a 1.120" compression height piston, a 6.385" rod, and a 9.755" deck height. That may be close on the counter weights, so check into that. You might have to step back to a 4.375" stroke, it'll only cost you about 15 cubic inches and a little torque.

That much stroke with relatively small heads and a reasonable hydraulic roller will make monster torque really early, around maybe just 500-1000RPM above cruise/towing RPM. It'll pull like a diesel.

If you do that, you're going to want to have that 4L80E and converter beefed up considerably, meaning Alto Red Eagle clutches, Kolene steels, a valve body kit, and a good converter.

[HDBD]

I had a very strong running tow rig a 94 dually with a TBI 454. I found a set of heads off a 366 truck engine that had a more compact chamber and true oval ports. Used a larger intake valve and some mild bowl work only. Used a mild Crane cam. Picked up 2mpg and noticable torque.

[Alan Roehrich]

I had a very strong running tow rig a 94 dually with a TBI 454. I found a set of heads off a 366 truck engine that had a more compact chamber and true oval ports. Used a larger intake valve and some mild bowl work only. Used a mild Crane cam. Picked up 2mpg and noticable torque.

One of the local Super Stock racers, Mike Lynch, was one of the first, if not the first, to take a stock carbureted 454 truck, add a mild cam, a set of headers, and the intake and heads off of a 67 396/350. It was like a whole different animal, the truck would pull any trailer you put behind it back then, never ran hot, and got decent fuel mileage.

Later, I built a 0.040" over forged flat top 454, same heads as Mike head, with 2.19 and 1.88 valves, some porting, a Weiand dual plane, 1-3/4" Hedman Camaro headers, and a Comp 268 cam. It made 450HP and 480 foot pounds of torque, it got 12 MPG with a 28' all steel goose neck trailer with 10,000 pounds of cabbage on it, there was maybe 2500 pounds of cabbage on the truck. It was an older truck, all steel, steel flat bed, steel wheels, 3.73 gears, and 3 speed automatic with no over drive. It went 200,000 miles before a guy ran him off the road and totaled it.

[gnicholson]

in a towing application the 96 and later vortec heads would be hard to beat. they have a 100 cc fast burn chamber to get the compression up.a small ft cam around 260 adv on 106to 108 would make the best torque in the rpm you need assuming the overlap would work with the pcm tuning you use

[cfm]

Not sure about headers if they would gain me something or not.

Even in the stock tbi form, headers pick up quite a bit of power on 454's. I consider it quite mandatory on anyone lookinf for more power from their 454's.

[DaveMcLain]

Running too high of a compression ratio is a real mistake in any sort of towing or heavy truck engine. 8:1 is about where it needs to be to keep the engine out of preignition during long periods of hard running with typical regular pump fuel. I know higher compression would help performance and lower EGT's but that's the way it is with a truck engine.

[Alan Roehrich]

Well, 8:1 compression leads to glowing exhaust manifolds, with cracks, excessive coolant temps, with the attending coolant system damage, low power, and poor fuel mileage. As soon as I got mine up above 9:1, all those problems went away. I didn't have detonation, because I was no longer lugging the engine to death at high temperatures for extended periods of time. I wouldn't give a thin dime for a low compression gasoline engine in a tow vehicle, I've seen what compression will do, and it is great.

You don't need a lot of timing, you don't need a lot of fuel, and you don't need to run those "RV cams" with such short valve timing that all you get is detonation and an engine that is sucking wind at 3000 RPM while you're stuck in second gear trying to pull a hill at 30 MPH with a line of traffic behind you cursing your very existence. Even GM finally wised up and quit building those sick 8:1 454 truck engines with 220cc intake ports and flat intake manifolds.

Build one right and you can also say good bye to burned thrust bearings, blue and/or ballooned torque converters, and trails of white smoke from boiled transmission fluid.

[coolchevy]

Alan,

why does all that sound so familiar to me...........

[DaveMcLain]

So what you're saying is that GM didn't know what they were doing when they designed the 366 and 427 truck engines?

[Alan Roehrich]

So what you're saying is that GM didn't know what they were doing when they designed the 366 and 427 truck engines?

I'm saying for a 30 or 3500 series tow vehicle, they figured it out, and called it a Vortec, we towed with one yesterday. A Super Stock racer figured it out about 1986 or so. Since the one I built went 200,000 miles, got 10MPG with no overdrive, with a total vehicle weight including the trailer of over 20K, and was still running strong as a tow vehicle with a heavy trailer when it was totaled, from personal experience, I can say it worked, really well. Mine was a cheap one, too, no fuel injection, no aluminum heads, no computer ignition control, flat tappet cam, old design intake manifold, and a 30 year old Rochester Q-Jet. The most hi tech piece on it was an MSD 6A with an MSD distributor. It didn't even have roller rocker arms.

I've never known an OEM to be perfect, and the 366/427 40, 50, and 60 series truck engines were designed in the late sixties. I figure technology and knowledge changed in the next 40-50 years. Just a little maybe.

[DaveMcLain]

The reason I recommend staying with a low compression ratio is because in this sort of application you're going to be running it right in an area where detonation is most likely(below 3500rpm) 99% of the time. 8-8.5:1 compression with about 205 at .050 on 110 sep in on 104-106, headers, Q jet, factory iron tall intake, oval port 454 will pull the hell out of a trailer and get respectable economy for such an engine.

[Alan Roehrich]

If you'll add a little camshaft, you can run over 9:1 compression for more torque without the excessive cylinder pressure from the small RV cams, and when you have to pull at 3/4 throttle up a hill at 3500 to 4000 RPM, you'll have a lot more torque to do it with.

The problem with those small cams and low compression is you can't make mid range power, so when you need to drop back to second gear to pull a hill, you stay stuck there, because you have torque dropping rapidly above 2500 RPM because it can't breathe through 205 degrees duration @ 0.050 tappet lift, and then the low compression becomes no compression at 3500 to 4000 RPM, your EGT goes through the roof, because your combustion temperature is out of sight, and then you're pinging the rings out of it. You can't put any timing in it at all to make up for lacking compression, because you're already detonating it to death. Then you'll be wondering why you're stuck with "all big block Chevy engines use a little oil" because you've beaten the rings, ring lands, and valve guides to death.

It's a 454, or bigger, it's not a 350, trying to make it breath through 205 degrees @ 0.050 is like feeding it through a straw. With a 205 @ 0.050" flat tappet and 8:1 compression, especially on 110 with 6 degrees advance, torque is over with at 3000 RPM, and there simply is not HP. So when you drop back to the next gear, and turn 3500 RPM to pull that hill, it just lugs and surges.

I've tried it your way, and tried it mine. My way I top the same hill going 65MPH instead of 45MPH, my headers aren't warped, my coolant temperature is 190 instead of 210, and everything under the hood is happy.

I stopped trying to make my big block Chevy think it was a Detroit Diesel years ago. It's a gasoline engine, it needs to rev freer, it despises being lugged at low RPM, it's the nature of the beast.