Gearing, Power & Tire Size Combo
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Author:  pyrOman [ Tue May 06, 2014 5:37 am ]
Post subject:  Gearing, Power & Tire Size Combo

So, I just saw this pix in thedrambadotcom's gallery and inmediately brought to mind the thought of power to weight ratio and the often talked about issue of RGBs vs IRS or straight axle conversions, and the need for a more powerful engine and the like. Back when I did the IRS'ing on the Dormy, I first bolted on the same tires I had with the RGBs which were very TALL. Took it for a spin and for the engine to be "happy" at around 3500 rpm, the Dormy was literally flying at 95mph!!! :shock:

That was the main reason why I swap them for the rim/tire combo from the Benzo which were much smaller in diameter and on 14" rims. That made a world of difference! So it then ran at a more comfortable 75mph @ the same 3500rpm. Still can do the 95mph but that's over 4000rpm. :razz:

Anyway, the deal is that while it could achive the same with the RGBs, the tires had to "match" the gearing. I had to put the TALL tires while having the RGBs. But then run smaller juans with the IRS. However, for it all to run smoothly, the engine had to produce more power to push the bus weight. This is where the stroker crank comes in as it produces more torque. Yes, of course more horsepower too but torque is what we all need for a bus. :-k

Now, look at the pix:


That could be a very fun vehicle to enjoy in the desert, but even around town, you will need some serious power in order to roll them GIGANTOMOUS tires!!! And of course the gearing on that transaxle has got to match the tires as well! That would be a perfect use for a phatchick early transaxle like the juan in the Plump Truck, which does well with the tall tires it has but tops out at around 70mph. :neutral:

Author:  pyrOman [ Tue May 19, 2015 5:51 am ]
Post subject:  Re: Gearing, Power & Tire Size Combo

Just stumbled unto this pix in thedrambadotcom's forum showing power/torque per rpm on a stock 1500 bus engine. :neutral:


Notice how peak power is at around 4000 rpm. :-k

I cruise the Dormy at around 3500 rpm = 70+ mph. At 4000 or over, it'll be going well over 80mph!!!! 8-[

So again, the engine/gearing/tire size combo is vital in order to have a comfortable long lasting set up for a happy bus driving experience. :cool:

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