24 bolt wheels with BFG Bajas - Runflat or No Runflat

[Autonomy_Lost]

I don't think the top speed is neccessarily about power, more about not exceeding max RPM's and overspinning the engine. More power would just help get you there faster.

 

[Hammer]

What’s the design margin? 50%? Higher?
Does anyone know? Has anyone boosted it higher with safe results?

Basic engine design for these motors means they have a more limited amount of boost because the heads tend to 'lift', then you get the blown head gaskets.
How much difference with ARP head bolts, etc. not sure. I know you can make more power, but at a fairly high price.
If you want to push those limits, put in a duramax with a 6 spd allison. Much better conversion with power and reliability.

 

[Hammer]

I don't think the top speed is neccessarily about power, more about not exceeding max RPM's and overspinning the engine. More power would just help get you there faster.

Above 80 mph, power really IS needed because of the wind resistance. Above 70 mph it is noticable.

 

[Action]

Above 80 mph, power really IS needed because of the wind resistance. Above 70 mph it is noticable.

Then make it more aerodynamic....

 

[Mullaney]

Then make it more aerodynamic....

View attachment 853531

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I rarely talk bad about somebody and their toy - but DAMN that is UGLY!

 

[TOBASH]

I think I threw up in my mouth, a little bit.

 

[Maxjeep1]

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I rarely talk bad about somebody and their toy - but DAMN that is UGLY!

I think it’s for sale, at least it was awhile back. 99,000 asking price

 

[T9000]

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I rarely talk bad about somebody and their toy - but DAMN that is UGLY!

Lol, but it still doesn’t beat the Pontiac Aztek

 

[T9000]

Basic engine design for these motors means they have a more limited amount of boost because the heads tend to 'lift', then you get the blown head gaskets.
How much difference with ARP head bolts, etc. not sure. I know you can make more power, but at a fairly high price.
If you want to push those limits, put in a duramax with a 6 spd allison. Much better conversion with power and reliability.

I did think about it, but for some reason something doesn’t feel right about modifying it that much, I would rather be passed by a Prius than change the engine, I love the way it sounds now that it runs well and how it feels, and it’s history.

 

[T9000]

I don't think the top speed is neccessarily about power, more about not exceeding max RPM's and overspinning the engine. More power would just help get you there faster.

Air resistance/ drag increases as you go faster by the square cube law, where if you double your speed the air resistance quadruples, therefore it takes a lot more power to go faster…or go more aerodynamic like Action pointed out with that beauty

 

[Mullaney]

I did think about it, but for some reason something doesn’t feel right about modifying it that much, I would rather be passed by a Prius than change the engine, I love the way it sounds now that it runs well and how it feels, and it’s history.

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Dang Right!
I am with you 100%

Cummins in my M-936 (with a new muffler) sounds pretty sweet to me. Makes a lot of noise, but it just sounds tough. Then my contractor neighbor up the road comes by with one of his tractors. Big 4 axle trailer and a big Cat engine under the hood. He rides the Jakes around the curve out at the end of our lot and THAT sounds REALLY TOUGH!

 

[Autonomy_Lost]

Air resistance/ drag increases as you go faster by the square cube law, where if you double your speed the air resistance quadruples, therefore it takes a lot more power to go faster…or go more aerodynamic like Action pointed out with that beauty

But your still limited to the max rpm of your engine, for a given transmission and gearing right? Point being...on an M998 with a 3 speed, you shoudn't exceed 55-60mph I'm told. If you were to add a turbo to the engine but keep the same transmission and gearing, wouldn't it still be a bad idea to exceed 55-60mph? By adding horsepower you havent actually increased the max rpm of the engine right?

I'm not trying to argue or make a point, just trying to learn.

 

[T9000]

I am not a mechanical engineer and I just transpose from electrical engineering, where Power = Volts x Amps (and there could also be a time component if the two are time/ phase displaced, but to keep it simpler we can eliminate that). That translated to the mechanical engineering would be Power = Torque x RPM, therefore you can increase power by only increasing torque with the RPM staying the same. In our case we are not talking about doubling the speed to 150mph, but increasing maybe by 20mph so most of it could be overcome by fighting the losses.
More torque will accelerate the car faster and more power can overcome the things that try to slow down the car like like air drag, friction, going uphill, etc.

In reality, rarely there is a silver bullet solution and usually there is a multi-prong approach in order to reach best results, like in this case could be changing the pinion and ring ratio, in addition to increasing the torque plus maybe even increasing the tire size or another combination of similar things.
I just said this very quickly as my kids are waiting for me to go on a road trip and I apologize if it's not clear, maybe someone with mechanical engineering or engine design background can help further. I personally enjoy this forum very much and I am very thankful with all the help you guys provided.

 

[Hammer]

Honestly, my M1123's gearing, motor, transmission combo works great!
I don't have the turbo, and like I said, wind gusts when pushing the higher speeds can be felt. But it really doesn't bother me.
I tend to drive in the 65 mph range more, and the engine sounds and feels nice in this range. Has enough power to still accelerate and pass someone on the freeway. And still does real well off road.
I think this combo is a really good middle ground setup.
Unless I had heavy armor and towed trailers a lot, then the turbo would be a nice addition. But gearing and tires, they are great as is!

 

[gringeltaube]

If you were to add a turbo to the engine but keep the same transmission and gearing, wouldn't it still be a bad idea to exceed 55-60mph?

Correct. Red line for rpms is there for a reason; to keep things on the safe side. If you wanted to go higher for extended periods, rebuild the engine and do something the military doesn't care about, that much: have every rotating part perfectly balanced!
Actually, that goes for every engine in this world...

 

[Sjoconnor]

Read this thread as I was about to research new tires for my M998. Called CSM army tire and inquired about what they had. On Monday 1/3 onorder 4 new BFG tires on 24 bolt rims. With run flats. They arrived today!! Brand new tires. Can’t wait to get them on.

Kudos to CSM. Great deal and prompt shipping.

 

[T9000]

Read this thread as I was about to research new tires for my M998. Called CSM army tire and inquired about what they had. On Monday 1/3 onorder 4 new BFG tires on 24 bolt rims. With run flats. They arrived today!! Brand new tires. Can’t wait to get them on.

Kudos to CSM. Great deal and prompt shipping.

What is the manufacture week/ year, it should be on the side of the tire, next to DOT, something like 34/20 (34th week of 2020)?

 

[frauhansen]

yes, you can balance them out with runflats, and then safely run them at highway speeds.
Getting a set of Centramatics or Balancemasters does help, because even being just a little out of balance makes things feel worse the faster you drive.

I've run Wrangler MT and MTR tires on both 12 and 24 bolt rims at 70+mph with the runflats installed and only occasionally get noticeable shaking, and that is with doing the tire work myself, no balancing, and centramatics.

Here in Europe we use something we calles "balance sand" or "balance powder".
the advantage is that the tire thus virtually balances itself. From about 15mi/h the sand is automatically distributed to where the imbalance occurs.
Whether this still works with runflat / is safe I do not know.
And because it is redistributed each time it does not bother that the tire wears out and changes over time.

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www-hofmann--powerweight-com.translate.goog

I could not find it directly in the us so i used google translate.

 

[gringeltaube]

Whether this still works with runflat / is safe I do not know.

It does not...! The powder (beads, pellets, etc.) would stick to the RF-lubricant and make a big mess.

The military uses external, stick-on lead weights on these.

 

[frauhansen]

Thats what i expected.