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The worlds Fastest Comanche


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The worlds fastest Comanche is currently located at a Chrysler building in Michigani. It was built to show the performance of the new 4.0L engine in 1987. It set a land speed record at Bonneville of 141mph and had a top speed of 146 MPH. GM did not take this lying down and hired Gale Banks to set a record with a S15 pickup in 1989. In the 240-261 cid class, the Banks truck went 183 MPH, totally blowing away the Jeep record. Banks continued to compain trucks and came back in 1990 with the Syclone, and set a record of 201 mph with a normally aspriated V6. I believe this was in the 261-305CId class.

 

So who cares? why is this important? Well I don' think it is right that a Chevy V6 holds a land speed record over a Jeep I6. This is one of those things that just puts the universe a little more out of wack. I think the situation needs to be rectified. To this end i have purchased a 1989 Comanche, LWB 2wd ( 4.0 of course) AX15 trans, and Dana 44 rear axle. I am collecting parts, and am looking to build the engine, It will not be easy to compete with the Banks organazation. The record is 20 years old, and technology has improved during that time. So i think a 4.0 can be competitive. I will be building it in my garage, with money out of my pocket, and help from anyone who wants to lend a hand.

 

Here is a some information on the engine restrictions.

 

The rules state that you can run a engine form the same engine family, but it must have the same deck height as the engine that came in the vehicle originally. The

E P/MP class is limited to about 261CID, so a 258 falls in good with the rules, but a 4.0 with a larger bore and a little stroke would probably out perform a 258. Some input from the group would be appriciated. You need a whole lot of HP to go 185 MPH

 

I want the worlds fastest Comanche to be parked in my driveway, and the second fastest Comanche to be in Auburn hills MI.Peter Lechtanski

The worlds Fastest Comanche Prroject

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Problem is, the customary way to stroke a 4.0L engine is to use a 258 crank. Even with NO overbore that brings it to 4.5L, which is 274.5 c.i.d. So you're really stuck with either using a 4.0L at maximum overbore and as much offset as you can grind into the crank, or starting with a 258 and running minimal overbore to stay under the maximum displacement.

 

The 4.0L has by far the stronger rods and better breathing head and manifolds, so IMHO that's the way to go, even if you're under the maximum displacement. Anyhoo, a smaller bore and longer stroke is not the optimum setup for maximum horsepower and RPM. I'd recommend staying with a standard-stroke 4.0L and a maximum bore of .060 over. You might get more on the bore, but it'll reduce cooling efficiency and exponentially increase the likelihood of an engine failure -- if you don't punch through the walls while trying to bore it.

 

Although I like the Renix setup, the newer heads and manifolds flow better and the HO puts out more HP (in stock trim) than the Renix. So I'd suggest perhaps converting to an HO ignition and injection. Among other things, I believe you can get power chips for the HO -- they aren't available for the Renix.

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The worlds fastest Comanche is currently located at the Chrysler Museum in Auburn hills Mi. It was built to show the performance of the new 4.0L engine in 1987. It set a land speed record at Bonneville of 141mph and had a top speed of 146 MPH. GM did not take this lying down and hired Gale Banks to set a record with a S15 pickup in 1989. In the 240-261 cid class, the Banks truck went 183 MPH, totally blowing away the Jeep record. Banks continued to compain trucks and came back in 1990 with the Syclone, and set a record of 201 mph with a normally aspriated V6. I believe this was in the 261-305CId class.

 

So who cares? why is this important? Well I don' think it is right that a Chevy V6 holds a land speed record over a Jeep I6. This is one of those things that just puts the universe a little more out of wack. I think the situation needs to be rectified. To this end i have purchased a 1989 Comanche, LWB 2wd ( 4.0 of course) AX15 trans, and Dana 44 rear axle. I am collecting parts, and am looking to build the engine, It will not be easy to compete with the Banks organazation. The record is 20 years old, and technology has improved during that time. So i think a 4.0 can be competitive. I will be building it in my garage, with money out of my pocket, and help from anyone who wants to lend a hand.

 

Here is a some information on the engine restrictions.

 

The rules state that you can run a engine form the same engine family, but it must have the same deck height as the engine that came in the vehicle originally. The E P/MP class is limited to about 261CID, so a 258 falls in good with the rules, but a 4.0 with a larger bore and a little stroke would probably out perform a 258. Some input from the group would be appriciated. You need a whole lot of HP to go 185 MPH

 

I want the worlds fastest Comanche to be parked in my driveway, and the second fastest Comanche to be in Auburn hills MI.Peter Lechtanski

The worlds Fastest Comanche Prroject

 

Just curious, are you TallPeter from the strokers forum?

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No, I am not Tall peter From the strokers forum, but I am tall (6' 6" ) and my name is Peter, and i did also post on the strokers forum. What better place to find out about engine stuff. Serach is cheaper then research.

 

I am looking to use some new technology to go for the record, for example a aftermarket efi controller, distributor less ignition, a timing belt drive for the cam, an external oil pump, a T56 ( 6 speed trans) Etc. I will document the modifications on the forum. Some things like the timing belt drive may have comercial viability.

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Some things like the timing belt drive may have comercial viability.

God, I hope not.

 

No offense, but I simply cannot see any advantage to the buyer in a timing belt that has to be replaced every 80,000 miles compared to a timing chain that goes 300,000 without a whimper.

 

But I know I'm old-fashioned.

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If you want to go those kind of speeds with ~4 liters of displacement, you will need to build a high revving engine, with torque near the top end. This will probably mean a custom designed cam, heavily ported and customized manifolds and heads. And just think of the kind of rods, pistons and even crank you need just to handle the rotationally forces at high rpms.

 

To go those kinds of speeds, you're probably looking at 600-700hp, for a minumum. Think nascar engine with less displacement (nascar limit is 358 ci, or 5.9l), but the same kind of HP.

 

I hope you have deep pockets, as I think you're gonna be looking at at least $30,000 under the hood.

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No offense, but I simply cannot see any advantage to the buyer in a timing belt that has to be replaced every 80,000 miles compared to a timing chain that goes 300,000 without a whimper.

 

The timing Belt will give you 10 more HP, and will help with the Cam harmonic problem when going high RPM, to set the record i only have to go 8 miles, to life cycle of the belt doesnt bother me. On the street, i would give you more power and better gas mileage.

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A Jeep 4.0L will run 10,000 RPM, too ... if you can get beyond the 6,000 to 6,500 RPM vibration range without self-destructing.

 

The 99 and up blocks were reinforced around the cam bearing area to help with this problem, I don't know anybody with any experience though. Hopefully by by removing the distributor and oil pump, and running a timing belt on a 99 and up block, the engine will perform better.

 

as for some of the comments about the hoursepower required, their are truck with even smaller displacment engines ( normally aspirated) that have exceded 180 mph. The fastest truck i saw was a Jessell 2003 (talk about a brick) with a 360 cid motor that went about 227mph.

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