BOLO

iTrader: (40)

Jeff, I was going through the wallaceracing calculator, and it seems even a 4.56 gear will get the car thru the lights at around 6700+rpm. Mike V(Quick95), if I recall uses this gear combo with his 4L60.

quik95lt1

iTrader: (7)

thats correct butch.......i run a 4.56 gear with a 29" tire on the 4l60e however you also must factor in coverter slip to the equation which will be different from one to the next........136mph puts me at around 8000-8100 coming through the traps.......as for the when to shift where to cross deal here is what i go by........

you want to shift the car where the power when it leaves the gear is the same as the power when it enters the gear.......you need to think about this in a acceleration vs. time not just acceleration.......you want to have the highest average power the whole trip down the track......

for example check out the graph below........this is my LS2 GTO with the T-56 trans in it and stock gear........i know my 3-4 shift drops 1350rpm @ ~6500rpm..........you can see where i marked off my shift position on the graph......i shift at 6800 with 400rwhp and come into 4th gear at 5500 with 400rwhp as well even though the car makes a 422rwhp peak at 6300 rpm.....notice how if i connect the two dots where i shift the line is flat.......this is optimal.......this gives me the highest "average" power through out the pull.....



now if i lower my shift point to 6300 i will go from 422rwhp down to ~5000rpm where i only make 375ish rwhp......now if i connect my two dots they are no longer straight........my average power is hurt because i didn't shift high enough.....so me going 500rpm past my peak power for my shift is my optimum point.......

the same issue will be encountered if you shift it too high.........you need to do the above calculations based off of your power band and figure out what is best for YOUR application......this is why i am constantly preeching dynos are a tuning tool only and peak power doesnt mean squat......sure i made 422rwhp but im faster than 420rwhp cars that are lighter than me.......why? because through my shifts my average power/torque is fantastic, i never drop below 400rwhp.........and this is what i do with my camaro as well......from the instant that motor goes above 6500rpm i make within 5rwhp all the way down the track, im essentally at peak power ALL the time........with my current converter i drop out of it a little im still not optimized.........my new converter being built by ATI right now should it hit right on the nose...........i make peak power at 7450 with my LT1.......flat power to 8000....right now my situation is this....

1>2 @ 7900 yields 6600 in 2nd
2>3 @8200 yeilds 6500 in 3rd (im over reving to compensate for the low shift rpm in the next gear aka i make the same power at 8200 that i do at 6500)

my new converter should put me here which is right in the butter zone for me
1>2 @7900 yields 6900-7100 in 2nd
2>3 @ 7900 yields 6900-7100 in 3rd
cross traps at 8000 at hopefully ~140mph


hope this helps!!!!!!!!!!!

now go get fast and get that tank to the shootout!!!!!!!

good luck
Mike

BAIN

iTrader: (5)

Thanks quik95lt1!

Someone has finally explained the importance of shift extension with data. I have searched so many times and there never seemed to be a real answer how this works. I have been trying to explain this to my converter builder the since the converter was built. I'm on my 2nd restall now and hopefully they got it right this time. They kept telling me that loosening the converter won't help.

My cam makes peak HP @ 6500-6600 and shift at 7000 with 6 hp difference. The original converter dropped back to 5200 which lost 40 HP from peak. The first restall I went through this information with them again to loosen it up. What they sent me was a converter that dropped back to 5600 which lost 30 HP from peak.

The last restall hopefully they got it right! I told them I wanted the shift rpm to drop back to 6000-6100 where I only loose 8 HP from peak. I think this will pick up some ET staying in my powerband from 6100-7000. I haven't had time to test it yet, but I will post results when I do. I will only be able to test in the 1/8mi though

quik95lt1

iTrader: (7)

yea i had a huge change when i reflashed mine........i had a 4000 stall and the car just hit a wall at 10.7 @ 128......just wouldn't go any faster didn't wanna hear it........then i realized it one day, i was on the highway watching a friend race with a 135mph car.......i put my foot in it following them and started reeling him in on the high end.......said holy **** i have horsepower lol.......reflased it to a 4800 and straight off the trailer went 10.38 @ 131...hoping to see 9.7x's with the new converter.......

BOLO

iTrader: (40)

Thanks Mike for chiming in, and thank you for explaining this more clearly, and showing it in a graph makes it even easier to see and understand how it works. And Jeff, you gotta check this out.

BAIN

iTrader: (5)

Quik95lt1 what were your 60's with the 4000 and 4800?

BADHAWK51

iTrader: (1)

I have been wanting to do this for a while. I need someone to go to the track with me a log some runs it's to hard to watch the tach during wide open blasts to see the rpm drop between shifts.

quik95lt1

iTrader: (7)

no problem!!!


4000 went 1.43-1.45's with the front wheels
4800 goes 1.30-1.32 on the rear wheels
im hoping my new one will go 1.24-1.26's

heres a video of the 4000 converter........car just didn't have it......you can hear it wake up at 6700 or so......then fall way out when it shifted......as well as on the launch it just wasnt there.....
http://www.youtube.com/watch?v=eMudv...2&feature=plcp

heres a vid of the 4800 ......
http://www.youtube.com/watch?v=c_OYv...eature=related

now add a 29" tire to take care of the overrev situation on the top end and you get this.....
http://www.youtube.com/watch?v=sC42B...4&feature=plcp

data logger!!!!

Wicked94Z

iTrader: (26)

hey mike, a 1.30-1.32 on the back tire is around a 1.22-1.24 on the front tire. I think a 1.26 on your current motor setup with a better converter would bring 9.70s. Get a TH350 too

quik95lt1

iTrader: (7)

the goal is 9.60's i hope ur right......plus i got another 15-25hp in the works lol

BOLO

iTrader: (40)

Very impressive Mike. I think you have one of the fastest naturally aspirated LT1 in the country. Definitely up there with the big dogs like Rick Abare, Ed Wright, and Joe Overton to name a few.

LS6CamaroA4

Approximately 200 rpm past peak would be optimal. Same on shiftpoints.

Yullose

iTrader: (1)

Sorry to dig up this old thread, but given your excellent detailed explanation and dyno graph... I wondered how best to target shift points and gearing with a graph that looks like this:
The rev limiter is at 6600 so there was no point in pushing it beyond what was logged on the dyno.
The car is a '05 Vette with 4L65 / 3.15 gears and 27" tires.

Wicked94Z

iTrader: (26)

need to get rid of the limiter before you need to worry about optimizing shift points

StraightTimeStirrups

What is your guys opinion on a bolt on car gearing for the 1/8 mile? My local track is an 1/8 mile and I dont imagine hitting a 1/4 mile track for awhile. I would like to know what you guys would think would be a good rear end gear for this car? I am going to be building a 9" for the car so I will have a separate third member for a 1/4 mile if I ever get the chance to run at one.

For a Bolt On Track ONLY Car, what Rear Gear would you run for each track?

1/8 Mile Gear

1/4 Mile Gear

Mighty Whitey

What have you changed since your 11.04@122 pass?
If nothing has changed, and you know your rpm at 122mph, then you can directly relate that to what the fear change will do, just give yourself a little extra room to play with considering the converter will act a little different with more/less gear.
But yes, if you trapped 122@6700, and your motor pulls to 7200 then peters out, then I would try gearing it to run as close to 7100 as possible)

BTW, that website with the calculator's is a little off. Says my car with a 3143 race weight and 344 rwhp would only run 12.17@111mph. Over a full second, and 9mph off. Lol

deerslayinrednek

iTrader: (8)

All of the calculators I've saw use flywheel HP and not RWHP

BOLO

iTrader: (40)

If I can recall on my 11.04@122 run. With 4.10 gear/4000 stall and 28" tires, it was crossing the traps at only 61-6200 rpm. I think there's alot more if can gear the car to cross the traps at 7000-7100 rpm.