Planning to hit the 1/4 on Wed. It looks like the weather and temp should be about the same as the last time I went and ran 15.6.
This time I am planning to split gears (2.74,2.13,1.54,1.20,1,.78 ) and see how much I gain. Ofcourse I'll go through the traps using the 1.2 ratio (2nd over) I plan to run the GV without opening up the exhaust cutout to see where the gains are coming from. Then opening the exhaust also.
Current ET 15.6
Gear spliting. ? (-.4)
Exhaust cutout ? (-.3
New ET 14.9
Do you think I'll make it?


PS rear gear 3.07:1, 26.1" tire

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

If you shift at 6000 RPM you'll go through the traps the top of 2nd gear. I would guess you'll only see a 0.2 sec gain from gear splitting. You really need 3.91s to use 2nd over with the trap speeds you've been running.

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Joshua

If I shift at 6000 I'll run slower. The power falls off at 5000.
What about open exhaust gains?

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

You only get 5000 RPM out of your engine? I used to shift my Comp 264° (only 224°@ .050") cammed 225 at 5500 RPM. When I had the 4.10s and regular 1:1 4-speed for one race I ran it up to 5800 on the back straight at PIR. I did lose an oil pump gear that race though.

Again, you'll probably only see 1/2 the gains you're predicting (hoping for) from these changes. We can guess all day long so go get some time slips.

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Joshua

If that cutout is after your Y-pipe, you'll see nothing there.

0.1-0.3 is realistic. Course the air will be better?

Lou

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Home of Slant6-powered fun machines since 1988

+.10 to .00 from splitting the GV
-.10 to -.20 from opening the cut-out

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Slant Cecil