Considerations for a truck pull engine?

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Considerations for a truck pull engine?

Post by EngineTech1 » Fri Nov 03, 2017 8:59 pm

For anyone that has built engines for this application in the past, how does your approach vary from say a drag race application in the types of components or the approach to setting clearances and tailoring the power curve of the engine?

I'm looking specifically at NA big block stuff in the 500-540 cid range with conventional style heads, cast manifold, single dominator, wet sump, solid roller etc. 16-20 seconds worth of pulling with tire spin and a steadily increasing load. Lots of mass to get moving at the beginning, lots of load on the engine, and a sustained rpm for the majority of the pull.

I've got some things in mind that seem worth considering in this application but the majority of my experience has been with drag race and endurance circle track engines. Lots of on off throttle stuff or 1/4 mile passes that last less than half the time of these pulls.

Input is appreciated.

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Re: Considerations for a truck pull engine?

Post by In-Tech » Fri Nov 03, 2017 10:22 pm

Randy331 said he learned alot compared to his drag racing stuff, I'm sure he could be of some help. Keep in mind his team won EMC this year too.
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Re: Considerations for a truck pull engine?

Post by Walter R. Malik » Fri Nov 03, 2017 11:27 pm

EngineTech1 wrote:
Fri Nov 03, 2017 8:59 pm
For anyone that has built engines for this application in the past, how does your approach vary from say a drag race application in the types of components or the approach to setting clearances and tailoring the power curve of the engine?

I'm looking specifically at NA big block stuff in the 500-540 cid range with conventional style heads, cast manifold, single dominator, wet sump, solid roller etc. 16-20 seconds worth of pulling with tire spin and a steadily increasing load. Lots of mass to get moving at the beginning, lots of load on the engine, and a sustained rpm for the majority of the pull.

I've got some things in mind that seem worth considering in this application but the majority of my experience has been with drag race and endurance circle track engines. Lots of on off throttle stuff or 1/4 mile passes that last less than half the time of these pulls.

Input is appreciated.
Do you have a brand in mind and are there any specific rules which need to be followed ...?
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Re: Considerations for a truck pull engine?

Post by EngineTech1 » Fri Nov 03, 2017 11:39 pm

Walter R. Malik wrote:
Fri Nov 03, 2017 11:27 pm
EngineTech1 wrote:
Fri Nov 03, 2017 8:59 pm
For anyone that has built engines for this application in the past, how does your approach vary from say a drag race application in the types of components or the approach to setting clearances and tailoring the power curve of the engine?

I'm looking specifically at NA big block stuff in the 500-540 cid range with conventional style heads, cast manifold, single dominator, wet sump, solid roller etc. 16-20 seconds worth of pulling with tire spin and a steadily increasing load. Lots of mass to get moving at the beginning, lots of load on the engine, and a sustained rpm for the majority of the pull.

I've got some things in mind that seem worth considering in this application but the majority of my experience has been with drag race and endurance circle track engines. Lots of on off throttle stuff or 1/4 mile passes that last less than half the time of these pulls.

Input is appreciated.
Do you have a brand in mind and are there any specific rules which need to be followed ...?
Well specifically I'm talking about a 540 BBC. I have a friend that has started truck pulling and had a 540 built for it. Talking to him has got me thinking about how I'd approach a build like that. I'm thinking of specific mechanical things that might be different. Seems to me that on a long, high load pull like that there's the potential for getting some heat in the exhaust valve and chamber but besides that it just seems that getting the compression up and picking a cam and cylinder head/intake manifold design geared towards a more broad power curve than I would do on a drag race engine would be about it.
I'm just wondering if there are other things I might not be considering from a machining or parts selection perspective.

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Re: Considerations for a truck pull engine?

Post by RevTheory » Sat Nov 04, 2017 7:15 am

What about oil drainback from the heads?

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Re: Considerations for a truck pull engine?

Post by Walter R. Malik » Sat Nov 04, 2017 9:34 am

I won't get into specifics but, use high velocity, good flowing heads with a large camshaft and a bulletproof valve train.
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Re: Considerations for a truck pull engine?

Post by rebelrouser » Sat Nov 04, 2017 9:56 am

I have built a couple, for the lower 4x4 truck classes, pump gas, cast iron heads and some required iron stock intake manifold, As mentioned the Tommy Boy thread has lots of good info. My experience is that the pullers many of them think the engine is the whole determining factor in winning. But the guys that worry about suspension and wheel speed do most of the winning. In watching the local pulls, the guy that gets the sled moving the quickest the soonest is usually the winner. Once the box moves toward the end of the sled it stops you. If you have the HP, you spin out, If not enough HP you lug down and kill the engine. I try and pick a cam with a broad torque curve, and the best flowing heads they can afford. Rest is buying good parts to keep it together at the RPM's they want to pull. Again with many drivers its monkey see monkey do, if the other guy is spinning 9,000 rpm then that must be the only way to win. I have seen several guys get the engine capable of spinning the high RPM and making big HP, only to watch them wheel hop down the track, and destroy clutches trying to get the sled moving. You need to sit down with the owner and review the total gearing and suspension of the truck and then build an engine to match the truck. One way truck pulling is a challenge is you have no time trials, you get one or two hooks a night. If the combination is not right it takes a lot of hooks and destroyed parts to sort it out.

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Re: Considerations for a truck pull engine?

Post by Frankshaft » Sat Nov 04, 2017 9:58 am

I won't get into specifics either, but I will say this. This ISN'T a semi, don't think about low rpm tq. Think gear and wheel speed. Here we go again.

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Re: Considerations for a truck pull engine?

Post by Frankshaft » Sat Nov 04, 2017 10:49 am

rebelrouser wrote:
Sat Nov 04, 2017 9:56 am
I have built a couple, for the lower 4x4 truck classes, pump gas, cast iron heads and some required iron stock intake manifold, As mentioned the Tommy Boy thread has lots of good info. My experience is that the pullers many of them think the engine is the whole determining factor in winning. But the guys that worry about suspension and wheel speed do most of the winning. In watching the local pulls, the guy that gets the sled moving the quickest the soonest is usually the winner. Once the box moves toward the end of the sled it stops you. If you have the HP, you spin out, If not enough HP you lug down and kill the engine. I try and pick a cam with a broad torque curve, and the best flowing heads they can afford. Rest is buying good parts to keep it together at the RPM's they want to pull. Again with many drivers its monkey see monkey do, if the other guy is spinning 9,000 rpm then that must be the only way to win. I have seen several guys get the engine capable of spinning the high RPM and making big HP, only to watch them wheel hop down the track, and destroy clutches trying to get the sled moving. You need to sit down with the owner and review the total gearing and suspension of the truck and then build an engine to match the truck. One way truck pulling is a challenge is you have no time trials, you get one or two hooks a night. If the combination is not right it takes a lot of hooks and destroyed parts to sort it out.
I agree, but disagree. The part where you say the monkey see, monkey do part and they wheel hop and break stuff. My answer, don't detune the engine because of this, but FIX the truck so it doesn't do that anymore, and pull farther. No different than drag racing, road racing, circle track etc. WAY more to it than just the engine. Everything from the front bumper to the rear bumper and everything in between plays a part. And the guys that understand that concept and really take it to heart, are the fastest and pull the farthest. And a lot of them don't even have the most power.

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Re: Considerations for a truck pull engine?

Post by EngineTech1 » Sat Nov 04, 2017 10:53 am

RevTheory wrote:
Sat Nov 04, 2017 7:15 am
What about oil drainback from the heads?
That's a good point. The length of time those things spend at full song allows for a lot of oil to be pumped up top.

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Re: Considerations for a truck pull engine?

Post by EngineTech1 » Sat Nov 04, 2017 11:04 am

Frankshaft wrote:
Sat Nov 04, 2017 9:58 am
I won't get into specifics either, but I will say this. This ISN'T a semi, don't think about low rpm tq. Think gear and wheel speed. Here we go again.
Yeah I'm not thinking about it like it's a semi.

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Re: Considerations for a truck pull engine?

Post by RevTheory » Sat Nov 04, 2017 11:25 am

EngineTech1 wrote:
Sat Nov 04, 2017 10:53 am
RevTheory wrote:
Sat Nov 04, 2017 7:15 am
What about oil drainback from the heads?
That's a good point. The length of time those things spend at full song allows for a lot of oil to be pumped up top.
I don't know if rules allow it or if it's possible with iron but maybe you can do an external drain straight to the pan to help reduce the chocolate smoothie, horizontal tornado effect.

I can imagine quite a power loss swinging a long stroke around at 7,500+ rpm.

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Re: Considerations for a truck pull engine?

Post by EngineTech1 » Sat Nov 04, 2017 11:50 am

rebelrouser wrote:
Sat Nov 04, 2017 9:56 am
I have built a couple, for the lower 4x4 truck classes, pump gas, cast iron heads and some required iron stock intake manifold, As mentioned the Tommy Boy thread has lots of good info. My experience is that the pullers many of them think the engine is the whole determining factor in winning. But the guys that worry about suspension and wheel speed do most of the winning. In watching the local pulls, the guy that gets the sled moving the quickest the soonest is usually the winner. Once the box moves toward the end of the sled it stops you. If you have the HP, you spin out, If not enough HP you lug down and kill the engine. I try and pick a cam with a broad torque curve, and the best flowing heads they can afford. Rest is buying good parts to keep it together at the RPM's they want to pull. Again with many drivers its monkey see monkey do, if the other guy is spinning 9,000 rpm then that must be the only way to win. I have seen several guys get the engine capable of spinning the high RPM and making big HP, only to watch them wheel hop down the track, and destroy clutches trying to get the sled moving. You need to sit down with the owner and review the total gearing and suspension of the truck and then build an engine to match the truck. One way truck pulling is a challenge is you have no time trials, you get one or two hooks a night. If the combination is not right it takes a lot of hooks and destroyed parts to sort it out.
Yeah, I've been thinking over the concept of the truck pull engine since a friend of mine has gotten into it and been getting his truck sorted out. I have no involvement in it other than listening to him about his trials and experiences. I have no customer in mind; I'm just doing this as a mental exercise trying to think of how I'd approach it from a durability and reliability standpoint. I'm not really asking for cam specs or port designs.

So far as I can tell from a machining and build standpoint it's not much different than building any other race engine except with an eye towards crankshaft strength and considering oiling and exhaust side heat during the pull. I'm thinking skip the light weight crankshaft, set up the bearings like an endurance engine, run slightly larger exhaust guide clearance and maybe stick to stainless exhaust valves.

I have a pretty good idea how I'd approach the port and manifold work and build the heads.

I've seen some of the other factors like chassis setup play out with my friends truck as he's progressed. He's got his truck set up pretty well now I think. It pulls straight and loads the tires well and he's gotten rid of all the hop. He's still not winning pulls like he wants to and thinks he's down on power. I think theres more in his tune up and gearing that could be done.
He's got a 540 BBC that made about 970hp @ 7500 when it was dyno'd but I think it's down on power because it was dyno'd in cold dry air at around 800 ft elevation in the winter time and then he took it back to an area where most of the pulls are at 1100-1300 ft. elevation during the summer in high heat and humidity and never changed the tune. When he pulls it gets to that 7300-7500 range and flattens out and just won't pull any higher. He's looking for more wheel speed and want's to turn it to 8000 or higher. In my opinion it's a tune issue and probably running too rich and too little timing for conditions but I'm not the engine builder or tuner.

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Re: Considerations for a truck pull engine?

Post by Frankshaft » Sat Nov 04, 2017 11:58 am

They are pretty much steady state rpm engines. Other than the beginning where they are slipped to get going without blowing tires off. Otherwise, once rugged, they pretty much stay at max rpm the whole time until the sled drags it down. The good ones just dig a trench and don't go anywhere once the weight comes down on them, but the engine is still screaming.

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Re: Considerations for a truck pull engine?

Post by Abbottracingheads » Sat Nov 04, 2017 11:59 am

Truck pull engines are very similar to drag race engines.Dont need the super light cranks, but everything else needs to be, because you need to be looking for 9000 rpm instead of 7500. You need titanium exhaust valves because of cam and rpm if you want to run up front. Big bores and shorter strokes win. It has to move a lot of air to make big power.
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