I was just having a little fun with the calculator when considering transmission options for my car. So, I thought I would share a point about gear ratios. This exercise demonstrates how a small block can produce more rear wheel torque than a big block if geared properly with an overdrive transmission. Here is was we use for a format: Big block assuming 510 ft lbs of torque using a TH 400 trans with a 2.48 first gear and a 3.42 rear axle ratio. Here is the math: 510 ft.lbs. X 2.48 X 3.42 = 4,326 ft.lbs. or rear wheel torque Small block assuming 410 ft lbs of torque using a TH 200-4r with a 2.74 first gear and a 3.9 rear axle ratio. Here is the math: 410 ft.lbs. X 2.74 X 3.9 = 4,381 ft.lbs. or rear wheel torque So, there you have it. A properly geared small block with an 200-4r OD trans will have more rear wheel torque than a big block with over 100 ft lbs more torque than the small block. From a practical standpoint, this does assume that the small block is capable of more RPM than the big block which in most cases will be true but not necessarily for Buicks. Not to be overlooked but the 70 mph cruise RPM for the small block with an OD tranny is 700 rpm lower too. The subsequent fuel mileage is worth noting also.
While true, it's a bit like trying to understand the height of a tree by looking at a leaf. Taking a broader look at the area under the torque curve of each engine and what will happen in all forward gears will tell a bigger story. Devon
4575 lbs, 3.07:1 gears. With the cam timing I'm running, low rpm torque is a thing of the past. The converter gets the engine to about 3200 rpm immediately and off we go. Devon
I want to play this game. Procharged big block, 200-4r, 3.73 6643 ft # at the rear wheels. oops no rear tires! This is just like Calvin Ball.
One factor to consider is what I experience with my 4.10 geared small block, although it's not a Buick 350. Then again, the numbers posted aren't brand specific. Anyway, we only have an 1/8 mile track close to us and many times I have beat cars in the 1/8 that would clearly beat me in the 1/4 because my small block doesn't pull as hard as a big block does for the second half of the track. I've had quicker ET's in the 1/8 against cars that have had 5mph on me in the traps. The big block guys really hate me for this, especially the trailered ones with open headers and slicks :laugh:
No question about it Bill. That is why I set all my cars up properly before the hot motor ever goes in. There is nothing more pitiful than a car with a hot motor that can't make a good number at the track because it is not set up properly. Except for maybe the cavalcade of excused offered by the owner.
You have some interesting numbers and fun to ponder. I have been on both sides of this topic. 350 4sp with 3.08, 3.36, 3.42, 3.90, 4.56 gears. Also 455 4sp 3.42, 3.90, 4.56. These combos were all in the same car over a 30 year period. I had the same thought in the late 80s and put together a 350 hp buick 350 with 4.56s and 4sp of course. It was pretty quick and very "bullit proof". Then about 6 years ago the 455 went in . The 455 with 3.42s wasted every ET the 350 had put up. This is why we dont race on paper.....
If I pull 4 plug wires off my 455, yes, a small block can make more torque. Anyone can stuff a potato in a tailpipe. Set the 2 up the same, and I'm pretty sure the results will be different.
two good postings there! I really like the part about we don't race on paper. ( or in my case I don't currently race:laugh: )
You have to look at the actual Tq/Hp numbers over the entire rpm range and not just the rated torque from the factory at one rpm which is the basis for the calulation that kicked off this thread.
There are a ton of factors the influence the eventually ET and MPH of a drag car. In the end, it is all about the horsepower to weight ratio. That is just the way it is. The reality is that a high winding small block with the same horsepower as a low RPM big torque big block will run the same numbers as long as it is geared to take advantage of it's extended RPM capability. When it comes to big block Buick compared to small block Buick, this just doesn't work because the big Buick heads flow more air than the small block heads. So, the small block Buick will never be able to produce as much horsepower. Either way, it is a fun exercise to show what the right gear set up can do for performance.
That is the key! Picking a combination to work together... The 3.07 gear is fine since you get your torque multiplication from your 3200 stall torque converter letting the cam get into its "power-band".
