I can't really see what you're getting at there Sin. Please elaborate, specifically on the mechanical limits you mentioned
But I will make the following post to show you what I understand of gearing, power delivery, and what I tihnk you were getting to.
What I can say is engines with broad torque curves (diesel-powered drag cars & big V8 drag cars) can use 2 and 3 speed transmissions (Powerglide, for example) because they have the available torque to turn long gears. Not to mention these types of transmissions don't really multiply torque like a transmission with 5+ gears. I see the Mazworx/Micks Motorworks "S15" uses a G-force 5speed clutchless transmission. To me, that translates into the SR20 they're using simply doesn't have the available torque to run a long gear set with a minimal amount of gears. They need more gears to keep the engine in it's peak power range for maximum acceleration. Nothing wrong with that, it's just what is needed for the application. If you had a 1800ft/lb diesel engine and have it geared to go 200mph, you don't need the lower gears for torque amplification to get moving (this is the reason 18-wheels have 17 gears- not because they always need it, but to super amplify the torque to move heavy loads). If anything, in theory it would be easier to make a 18-wheeler spin tires because of how much the short gears amplify torque, but they run out of RPMs too quickly. An unloaded 18-wheeler cab can accelerate just fine with skipping/splitting gears. I'm sure QD can elaborate on just what/how many gears can be skipped when driving a cab. Point of that is, without the [heavy] load, the usable range of RPM, is longer because the amount of torque required to accelerate is less. With a heavy load, the usable RPM range is reduced because more peak torque is required and shortening (splitting and hi/low range) the gears keeps the engine in the usable RPM range. This is a direct relationship to the SR20 powered car using/needing 5 gears because it doesn't have a broad enough RPM range when making peak power to use long gears.
Going on that you said "if you were to put [a diesel engine] in a real car chassis, it would probably spit axles", is kinda void IMHO because you wouldn't use X engine on Y driveline or Y enigne on X driveline- X engine with X driveline, Y engine with Y driveline. I understand what you're getting at with shock load though- sending 1000+ft/lbs through the driveline at launch and using torque to accelerate vs 400ft/lbs at launch and using RPM generated horsepower to accelerate as available torque decreases (your statement about "the stress transferred through the body lightens and during the course of acceleration"). But the shockload might not be as bad as you're thinking because the gears aren't really multiplying the torque output through the transmission- the powerplant makes enough torque to accelerate. Shorter gears/multiple gears are used for amplifying/multiply power output because the powerplant itself does not make enough to do all the work on its own to start accelerating. I don't think there is much to get into when talking about driveline loss and required equipment to handle power either because it works both ways....if you're making big power, you need the parts that can handle it. But the less moving parts you have on the driveline, the less loss there is.
Like I said, I don't mind a civil discussion at all, nor do I mind being corrected. Heck, while typing that up, I skimmed over a few builds of drag cars, watched a video to completely understand how a semi-truck's transmission works (I knew the basics, but seeing the high range and low range being used with the splits was helpful) and saw pictures of really cool engine builds and turbo setups.
Originally Posted by Doppelgänger
I can't really see what you're getting at there Sin. Please elaborate, specifically on the mechanical limits you mentioned
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