4.10's & 150 shot Update
 

i have a 87 rx7 with a 95 lt1/t56 swamped in , it goes 13.0's with a bone stock not even headers lt1, the madza has 4.10's from the factory stock and the tallest tires i can fit under it are 26" , how high do lt1's rev on a 150 shot ? I know now the factory rev limiter is around 6100 tagging that on nos wouldnt be very good , am i fucked or can i just get it rev limiter raised and let it rev too 6500 ? i dont think shifting into 5th would help much

You don't want to shift into 5th on the Track.. you pretty much don't want to get out of your 1:1 Gear..that is where you are putting the most power down.
At 6500 RPM's with a 4.10 Gear and 26" tires you are goin to be at roughly 122mph..how fast do you think you will be crossing the line with the Shot?

Here is a Calculator..
http://www.idavette.net/tech/ratioc.htm

I ran 120mph in the 1/4 with a T56, 4:10, 26" tire combo...but my rev limiter was set to 7K and as said before I was turning 6500+ through the traps.

I would suggest at least swapping in a good set of valve springs before turning big RPM on a stock motor

Spinning it above 5800 would be completely pointless if the motor is otherwise stock. I mean you dont even have headers on the thing. Nitrous adds more power but it doesnt actually change the power band itself. You would be putting uneccesary wear on the motor.

And if the only reason you are even thinking about revving that high is because of the 4.10's then i would suggest you reconsider you gear selection.

ran the car last night new best 12.83@108 , stared at the tach and it was around 5800 crossing the stripe , hmmm looks like im best off looking into a cam ,headers and tune instead of going cheap with just a shot

70velle: theres no (that im aware of) other gears for the rx7 rear

my bolt on car made power till 6...peaked i think at 5500...headers do infact change the powerband as its unrestricted above 5200 or so anymore...

and it doesnt matter if you go past you 1:1 gear as long as the tranny car take it and youve got enough fuel do it...mightymoouse does it in his car making 900 through an auto and 12 bolt...

a stock motor should get valvesprings first though...id also do pushrods i hear simply doing them can add 10 hp...

I think you mean 1.6rr, valve springs will allow bigger lift of a cam, 1.6rr will increase the lift of any cam vs 1.5

Better valve springs would help prevent valve float at higher rpms, but would not gain you any power.

any1 else ? maybe a just a 100 shot I want a 11.xx timeslip and I dont have much $$$$ invested in the car and im trying to keep it that way :)

Auto RX-7's had a 3.90 gearset I think from what I've read over on v8rx7forum.

Yeah, limit the shot until you can rev higher with better flowing components. If you do spray big then shifting into 5th would be better than tagging the limiter.

How can you tell if you get valve float or not?

Your right, the only other gear available for a t2 rear is a 4.30. If you had a non-turbo rear though, you could put in the 3.90s that came in autos.

Do they not make other gear options for the RX-7 ? A nice set of 3:73's would be a good choice with the 150 shot. I shift at 6100, using 4:11's with full bolt-ons.




You will know when the engine has valve float and then it's to late, shift :D

i have a turbo II they only came with 4.10's , a 373 would be lovely :(

Hmmmm thanks for the replys. I think im going to
just spray a 75/100 shot + 27" tires should keep me just under the limiter unless it goes over 119 mph

Well I've been doing alot of testing,tuning and abusing, went with a HSW wett kit 100 shot, TR6 plugs,mail order mad tuner tune,235/60/15 bfg drag raidals , 5900 shifts ,shifting into 5th around the 900' mark my best pass was

60' 1.784
1/8 7.706@93.31
11.891@117.52

Good springs prevent the loss of power that comes from valve float. So they can "add" power, it is just power that was lost to worn out components.

My Head/Cam 150 shot car had 4.10s at first and I didn't like having to shift into 5th gear in the 1/4. I changed the gears back to 3.42 and although it crossed the line at 5800 in fourth and trapped higher, I never could get the car to ET as fast. It just wouldn't come out of the hole. Keep in mind this is a daily driver that I only wanted to run drag radials at near stock tire size with so my options were limited. For my particular situation I think shifting into 5th wasn't a bad option considering the outcome.

I would rather shifts gears more. and narrow the power band then widen the power band to shift less gears.