hey anyone know how much mph i can get out of my current setup

currently i have 4:10 rear gears and a 28 inch tall tire.
last time out the car was trapping in 3rdgear at 104.65 & 6,550 rpms.
redline is between 7,400-7,600 rpms

how many more mph can i squeeze out of this thing with with 4:10's

im looking to go about 118-120 when all is said and done,should be just enough to go my goal of 10.90's

 

i also want to be 300 rpms shy of my redline when i hit my goal

my motor makes all its power from 4,000-7500, so keeping it close would be best,even if that means going back to a 26 inch tall tire

 

something doesn't sound right because my car used to trap 117-118 with 4.11s and 28" slicks and I think I was around 6100 rpm-ish. Your converter must slip a lot more than normal. This was an old nitrous 305 engine.

6500 should be good for 132 with no slip, so take off 5-8% of mph for converter slip.

 

i traped 105.99 and was teching 6800 with 4.10 and 28in slicks.

 

What is your 1/8th mile et and MPH?

 

8.3 & 83.29

 

Many years ago with a 383, I had 26" tires, 3.27 gears and ran 117-118 mph at 12.0 shifting at 7000. It wasn't geared properly as I was crossing the finish line around 5000 rpm.

What's the converter's stall speed?
What's the camshaft's advertised duration?
What rpm do you shift at?

You don't shift at the red line. The red line is where the valves start to float. You shift at or just past where the engine makes the most HP. Going past that point and the car isn't accelerating any faster.

Doing a quick check on your converters slippage based on the numbers you've given.

Tire diameter 28"
Finish line rpm 6550
Finish line mph 104.65
Gear ratio 4.10

Calculated converter slip = 21.39%

That's terrible. You need that to be below 10% to make MPH. The converter in my car stalls at 6000 rpm and I have a calculated slip of only 4.5%. There's either something wrong with your numbers or you probably have a bad or wrong torque converter.

I just noticed you have a turbo. That may be part of the problem.

Bugga, I don't read sigs. 700R4 and 4.10 gears is probably too much first gear. The 4500 stall converter might be OK but I still need the advertised duration and the turbo may skew the numbers. You're also trying to do this with a tiny turbo'd 3.1 V6. Even with a turbo, it's probably having a hard time breathing at the top end.

 

was originally a tci 3k stall that i sent back and had them lossen supposed to stall at 4,500 now. but i can tell u its looser then that cause it goes over 5k soon as i come off the footbrake.

the cam is 268/272 adv
been shifting the car at 7k rpms.ive had the motor to 7,800 already it didnt float the valves but i do not want to be reving this thing that high. the pone time i did take it that high was an accident.

this thing does pull right till around 7,500 so it is making power up there
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im gonna go back over a few data logs in order and see if maybe the trans is starting to let lose in the car as well

 

At what rpm does the motor make peak hp and whats the safe rpm limit of the valvetrain?

Looks like you have enough engine power for 106MPH as it stands now.

changing to a 5.13 gear would put you at just under 7000rpm thru the traps at 106 ish.
5.57's would have you traping at 7500+rpm @106 ish. probabily a bit too much.
A 5.38 would get you up there and leave some rpm room for more horsepower (engine improvments) that will raise the trap MPH and rpm.

Once the car is geared properly the converter will be much more efficient.

What shift point creates the lowest et?

is this a 10" street converter behind a V6? I would have started with a custom 7" or 8" converter for a V6.

 

I was hoping that was a misprint. With 268/272 advertised duration, you have WAY to much stall. That's probably why it's slipping so much. You need a converter that stalls no more than 3000 rpm for that mild cam. If those cam specs were at .050" lift, it would probably be better.

That converter needs a cam with 290-305 advertised duration.

 

i havent dynoed the car yet, im actually still tunning it, im just about ready to throw an aditional 12 psi of boost at the motor

and its a 9.5 inch converter

 

ok last 2 data logs 1st pass 13.4xx@101.xx


car came out of the hole at 3k flat off the foot brake with 5 psi
within .300 of a second the motor went to 5,520 with the 1-2 shift at 6,600

bottom rpm of the shift was 4,440 and again within .300-.400 the motor went to 5,400 it holds for a brief period that climbs to 6,500 for the shift

2-3 shift bottoms at 5,541 and within .200 goes right to 6,200 and holds till the throttle is lifted


run 2 data log 2 13.00 @ 104.xx

out of the hole at 3,600 and right back to 5,200 within .400 of a second
shift at 7,100 with the shift bottoming out at 4,600

the intresting thing in this datalog is befor the motor hits 7k it went from 6,100 right to 7,100 within .200 of a second
im starting to think its flaring on the shifts and possibly slipping

after the shift bottoms it goes back to 5,200 and extends fo rthe rest of 2nd gear shiftds at 6,300 (2-3 shift) and bottoms at 4,300

then again within .200 its back up to 5,400 were it holds and then climbs out to just under 6,500 in the traps

 

Sounds like tire spin to me. What are you using for tires?

If you're going to add that much boost I'd switch to 110 octane race gas
or your gearing/converter will be the least of your problems.

 

i highly dobt its tire spin the car has a set of 28x10.5x15 mt drags on it

fbird i can get 21-23 psi out of it on pump gas,but i am installing some meth injection in the next few days,im just waiting for my nozzle to come in
i run a very limited amount of ign timing in the motor 10-12* once i get the meth in i should be able to bump it to 16-18*,hell my friends with the gn's run upto 23* with 23+ psi of boost