Beach Bum vs BBA: The answer
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Drifting
Joined: Jun 1999
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From: Garden Grove CA
Beach Bum vs BBA: The answer
Although some parts of it got a little testy, the recent topic http://forums.corvetteforum.com/zerothread?id=374695 contained some thought provoking ideas on horsepower, e.t., torque converters, and 60' times at the drags.
Let me gently step past the bumpy parts of the replies to that topic, which although they strayed from the original posters question, still covered good material - however, there was a bit of it that was like two ships passing in the middle of the night. To that end, BOTH Beach Bum and BBA were correct.
Let's consider the case of Holeshot, the lucky forum member getting 12.1x e.ts. out of a 383 lower end using an amazing amount of factory L98 parts. The issue under fire seemed to be how much horsepower was being made since he was still running the stock 1,400 rpm stall torque converter. Normally we might expect that a low stall rpm torque converter would make for a slow 60 foot time. If the 60' time were 2.0x or 2.1x seconds then yes indeed, it would take serious horsepower to make the rest of that run into a near 12 flat e.t. As it is Holeshot actually gets excellent 1.6x second 60' times, and thus he ends up with the near 12 flat e.t.'s.
So let me state the obvious: 60 foot times predict more about your e.t. potential than anything else, that includes torque converter stall rpm, or maximum dyno horsepower, etc.
The interesting thing is how a particular combo can be optimized, and its not always the way many would think. Confused about how Holeshot gets 1.6x second 60' times with a low 1,400 rpm stall converter? - I'm not. Sixty foot times are all about laying as much torque to the ground as possible off the line. Many people presume that they must increase the stall rpm to do this. However, what no one knows is just how much off idle torque Holeshot's combo of a stroker engine using the L98 parts creates. What he has done is the same thing Beach Bum, Corkvette, Ralph, and others have done, simply to properly match components. Consider that an L98 is known for down low torque, and everyone knows that low to mid range torque is increased when a 350 is stroked (and bored) out to 383. So what he has done is to pile torque upon torque, which makes the stock ~ 1,400 rpm stall converter the right choice in his unique combo. One note should be made: when you increase an engines low rpm hp and tq, the stall speed on any given converter will actually happen at a slightly higher rpm. It is interesting to note when Holeshot asked in another topic about changing his stall rpm, several replies cautioned that would probably slow him down by hurting his 60' times.
So yes, if your 60' times are slow, you will need more horsepower to make a strong e.t. But if you work your combo right and get great 60' times, then quicker e.t.'s can be had with less horsepower. Kudos to Corkvette for getting darn close to the 10's with *only* 370 ish dyno proven horsepower - must be the ram air effect!
Who knows where this will lead, I hope others will stop to think more about how to optimize a performance combo rather than assuming some things, like the need for a higher stall converter if it would end up wasting a strong part of your powerband.
Thomas
Let me gently step past the bumpy parts of the replies to that topic, which although they strayed from the original posters question, still covered good material - however, there was a bit of it that was like two ships passing in the middle of the night. To that end, BOTH Beach Bum and BBA were correct.
Let's consider the case of Holeshot, the lucky forum member getting 12.1x e.ts. out of a 383 lower end using an amazing amount of factory L98 parts. The issue under fire seemed to be how much horsepower was being made since he was still running the stock 1,400 rpm stall torque converter. Normally we might expect that a low stall rpm torque converter would make for a slow 60 foot time. If the 60' time were 2.0x or 2.1x seconds then yes indeed, it would take serious horsepower to make the rest of that run into a near 12 flat e.t. As it is Holeshot actually gets excellent 1.6x second 60' times, and thus he ends up with the near 12 flat e.t.'s.
So let me state the obvious: 60 foot times predict more about your e.t. potential than anything else, that includes torque converter stall rpm, or maximum dyno horsepower, etc.
The interesting thing is how a particular combo can be optimized, and its not always the way many would think. Confused about how Holeshot gets 1.6x second 60' times with a low 1,400 rpm stall converter? - I'm not. Sixty foot times are all about laying as much torque to the ground as possible off the line. Many people presume that they must increase the stall rpm to do this. However, what no one knows is just how much off idle torque Holeshot's combo of a stroker engine using the L98 parts creates. What he has done is the same thing Beach Bum, Corkvette, Ralph, and others have done, simply to properly match components. Consider that an L98 is known for down low torque, and everyone knows that low to mid range torque is increased when a 350 is stroked (and bored) out to 383. So what he has done is to pile torque upon torque, which makes the stock ~ 1,400 rpm stall converter the right choice in his unique combo. One note should be made: when you increase an engines low rpm hp and tq, the stall speed on any given converter will actually happen at a slightly higher rpm. It is interesting to note when Holeshot asked in another topic about changing his stall rpm, several replies cautioned that would probably slow him down by hurting his 60' times.
So yes, if your 60' times are slow, you will need more horsepower to make a strong e.t. But if you work your combo right and get great 60' times, then quicker e.t.'s can be had with less horsepower. Kudos to Corkvette for getting darn close to the 10's with *only* 370 ish dyno proven horsepower - must be the ram air effect!
Who knows where this will lead, I hope others will stop to think more about how to optimize a performance combo rather than assuming some things, like the need for a higher stall converter if it would end up wasting a strong part of your powerband.
Thomas
