Moroso Speed Calculator 89650

[steve cowan]

I am a fan of the slide rule,it is something to work towards. With my own combos it is usually 15hp or so relevant.
As been discussed previously if you are not using the potential power of the engine work on the rest of the car and leave engine alone.
This is another chart worth looking at
20220815_160601.jpg

20220815_160601.jpg



I just had another look at this chart.
Some of it I can match almost to the number. But I'm trending towards more top speed than the chart predicts.
Case in point: From 2009. (uncorrected)
Chart calls for a 1.70 60', and a 12.75 ET. Very close to my time slip.
12.78 @ 105.1 8.088 @ 83.94 1.71 60’
But I'm trapping several MPH higher in the 1/4. 105.10 vs 102.30.
What's the take away from that. Gearing?
Actually, all of my dragstrip passes, even as the car got more powerful, would always show more MPH than the ET would suggest. Eventually my 60' started going away (tires) so it became even more skewed. Adding more rear gear, which I did, 3.73 vs 3.27 made the 60' worse as the tires (and suspension truth be told) just weren't up to it.
12.77 @ 106.58, 8.130 @ 83.75, 1.78 60'. (also uncorrected). There's a half second missing there by my reckoning.

Years ago with a 500hp 383 combo with my 9" 4200 rpm converter I was running 11.4s @ 123mph
A week later I run with a new 8" converter and picked up 3 tenths in the 60ft which carried incremental entire run but was down nearly 2mph.
11.10 @ 121.30mph
A few guys said converter slip but I just figured I got to the finish line quicker .
I still run the same converter today and for me it was a game changer.
I have done dozens of passes testing between 9" and 8" converters and 8" wins every time regardless of power output.
430 hp - 600hp
The gearshift drop has changed in rpm with power output, at the moment it falls back to 6000rpm on the shift, with my upgrade of the dart block and the engine should make 650hp hopefully the drop on shift will be 6500rpm with same converter/ gears and tyres

[steve cowan]

I forgot to mention
I have talked to guys over last couple of years at the track who have changed rear gear ratio with no other changes and expected ET improvements.
All have said the only thing that happened was rpm increases with no ET gain.
My opinion is gear/ tyre diameter go hand in hand and also what does there engine combinations do after peak hp,I think most street car guys stuff falls off a cliff quickly.

[skinny z]

Years ago with a 500hp 383 combo with my 9" 4200 rpm converter I was running 11.4s @ 123mph
A week later I run with a new 8" converter and picked up 3 tenths in the 60ft which carried incremental entire run but was down nearly 2mph.
11.10 @ 121.30mph
A few guys said converter slip but I just figured I got to the finish line quicker .
I still run the same converter today and for me it was a game changer.
I have done dozens of passes testing between 9" and 8" converters and 8" wins every time regardless of power output.
430 hp - 600hp
The gearshift drop has changed in rpm with power output, at the moment it falls back to 6000rpm on the shift, with my upgrade of the dart block and the engine should make 650hp hopefully the drop on shift will be 6500rpm with same converter/ gears and tyres

Something I'm hoping the new spec converter will address.
You mentioned the S/S guys. One of our own here, vortecpro, had a few enlightening things to say about that subject in particular.

I forgot to mention
I have talked to guys over last couple of years at the track who have changed rear gear ratio with no other changes and expected ET improvements.
All have said the only thing that happened was rpm increases with no ET gain.
My opinion is gear/ tyre diameter go hand in hand and also what does there engine combinations do after peak hp,I think most street car guys stuff falls off a cliff quickly.

One thing I discussed with Mike Jones was the power past peak. Like the converter, I'm hoping that the cam will give that bit needed at the top of each shift. Sims (for what they are) are showing table top flat for power past peak. Peak at 6k, flat 6000-6500. It'd be the goal to run in about a 2000 RPM window. 4500-6500. Initial talks with a couple of converter companies are suggesting the little engine might not be stout enough to realize 4500 stall and keep the lockup function which I still wish to maintain. That said, the 4L60 isn't exactly a dragstrip star so there are compromises made already.