What is the fascination with deep gears and compression? Another rant.

[A/Fuel]

My calculations are based on Tire size, RPM, and rear gear ratio.........it has nothing to do with the power the motor makes..........

Thats not what I ment, your confusion was in the 8971 so called rev limiter set at 8250. It is obviously defeated

[TC]

Thats not what I ment, your confusion was in the 8971 so called rev limiter set at 8250. It is obviously defeated

Go here, put your numbers in, the car isn't going to go any faster than what it's going to tell you, unless something changes......

http://www.wallaceracing.com/calcmph.php

You said 8250rpm, 36" tire, 3.20 rear gear, the equates to 276.23 mph........So how are they going 50 mph more than they are geared for?? Your math doesn't add up........... And even at 9000rpm the max speed would only be 301 mph.............Now if you add in tire growth and make the tire size 40", then we're getting in the ball park, but I already stated that earlier.......

[A/Fuel]

Again, the rev limiter is obviously defeated....

[A/Fuel]

The tires probably grow a little more than 4" also.

[TC]

Maybe an easier way to look at, is to look at ET and MPH, we all know if you want to run in the 9's you have to run around 150mph, so knowing that you have to figure what your redline rpm would be, how tall your tires are and then you would find the gear ratio that allows you to go 150mph with the rpm and tire specs that you have..........Now that you know your car is capable of going 150mph its your job to build a motor powerful enough to propel it to 150mph by the end of the quarter mile.........

[Beagle]

I think Squirrel and TSB are probably closest to this subject and have said kind of what I expected to hear. If you're making a pile of torque, you don't necessarily need a lot of gear for a cruiser. Todd's point is kind of taken, so is Autohack's. Bruab's comment on application is exactly on the money in my mind - it's all about what you are gonna use it for.

I think what Todd is saying is why all the cookie cutter advice, and overlaying Small Block / Small engine thinking on top of a 400 cube mill built for torque. Overdrives help a lot, but even with 30" tires, my first gen lightning w/ 4.10's and a .7 od is buzzy at 75. The second gen's (RIP) 3.55's and blower made first gear a lot more usable, and it was pleasant at 80+. Since first gear is primarily what you are sixty footing in, it will impact the ET.

[yellomalibu]

Wow, one tooth makes that much difference? What if you tried a longer crank set and the taller gears?

Changing to a longer or shorter crank makes a big difference.
This memory is going back over 20 years, but when I switched from 170mm cranks to 172.5mm cranks, it took me a long time to adjust.
You're correct in theory though. Longer crank should be able to accellerate a tall gear quicker... but it's harder to spin that longer crank at the same rpm you could turn the shorter crank. It could cause you to lose 5 - 15 rpms, and that's a decent amount of speed (please don't make me do the math or dust off the old 'Merckx to find out how much).

[SuperBuickGuy]

I dunno, the 70 GTO is heavy, like 4100-4200 heavy, and it had 2.93 gears in it for a while. That thing was still a beast and ran traction limited 13.50s@101 with a stock converter and a Th400. It ran the same with a 2004R and a stock converter. It had an additional issue of weak valve springs that limited RPM to about 4500 too. 60fts were around 1.90 with slicks, and its main problem wasnt the gears, it was the nose being so heavy. The front bumper is over 90lbs. It just wouldnt rotate and plant the rear tires. Not exactly a handling vehicle either despite big swaybars on it. That is a bit quicker than the 13.80s the 98 LS1 Formula with 2.73s did completely stock, and the LS1 isnt a deep grunt engine, though the 4L60E has a deep first gear and that has to be taken into account.

Make the grunt and it will still move.

Bikes are a bit different, I could climb steep hills faster than some of the guys I rode with, and I got moving quite a bit faster despite being 100lbs heavier than they were, probably due to the muscle mass I have. A lighter guy without as much muscle is going to have a harder time and need more gear to compensate being weaker, though he will have to work less to move the mass it wont be as easy in some situations. I wish I could still ride my MTB like I used to, as it is I can only go five miles before I hurt too much to continue.

I'm surprised the car ran the same since the 200r4 has a far lower first gear than the t400....

it's the short, fat guys who do best on the track because they have short legs, leverage, and can cheat the aero by tucking behind the skinny guys.... on the road I slaughter pretty much all comers on hills, all 200 lbs of me - my wife refers to me as that "ever vanishing dot in the distance." Still, if I weighed high school weight, I'd be 10x faster because I was 45 lbs lighter.... and weight is the great equalizer because my wife on her racing bike keeps up with me when I'm riding my mountain bike with my 100 lb lab in the baby trailer.... although we don't do hills in that configuration, because that truly defines the term "traction limited"

[SuperBuickGuy]

Changing to a longer or shorter crank makes a big difference.
This memory is going back over 20 years, but when I switched from 170mm cranks to 172.5mm cranks, it took me a long time to adjust.
You're correct in theory though. Longer crank should be able to accellerate a tall gear quicker... but it's harder to spin that longer crank at the same rpm you could turn the shorter crank. It could cause you to lose 5 - 15 rpms, and that's a decent amount of speed (please don't make me do the math or dust off the old 'Merckx to find out how much).

I can answer the 1 tooth difference - it's 3.5 rpm. (but don't let that be an excuse for you not to get out on your bike... it misses you - and the Cannibal monitors these pages and might just make you get out)

the problem is with longer cranks on banked tracks bad things happen when the pedal contacts the track; most track cranks are 165mm....

(laughing) and it's not just a theory. consider it this way - the best bicyclist make 1/10th of a hp, so we spend a great deal of time trying to maximize/idealize what we've got.... but the theories about gearing are far easier to see in that venue

last night with the 51 I did a lot better - now to get some more time on a bike to get my muscle back to racing shape (it's been a tough spring).

[squirrel]

Try a unicycle.....my kids have lots of fun figuring out tire size, crank length, speed, etc. And they still don't seem to be able to keep up.

it's good to see we're all staying on topic here.

[SuperBuickGuy]

it's related
it's about keeping the power in a specific rpm range - on my fixed gear race bike, I have to set my gear for how I feel, wind, track speed (track length and corner bank determine this), and who the competition is.... thus, setting your gear, compression ratio and strength of the block all are similar (spoken like a true lawyer, huh?)

[SpiderGearsMan]

thumpin is into street cruisers and sensible shoes

The Pro stock engines are only 15 to 1 static, but the dynamic compression ratio is about 17.5 to 18 to 1

[mike343sharpstick]

One nice thing about racing motorcycles is changing the rear gear is pretty easy, LOL.
When it comes to drag racing I have no information, but switching one or two teeth on the rear sprocket can sure make or break you day

[Bob Holmes]

Wow, one tooth makes that much difference? What if you tried a longer crank set and the taller gears?

Nah, he needs to be sucking on a leaf blower.

[Bob Holmes]

(please don't make me do the math or dust off the old 'Merckx to find out how much).

Damn you had a Merckx!! I wanted one bad. Had to make do with a Bianchi Campion Del Mondo.

And I certainly know what happens when a pedal hits the ground, still have two broken front teeth from the bike launch. I was fortunate enough to use my face to break the fall, nothing too important there.