got a new gear 3.15 was 3.73 - manual transmission needs it

[petersen302]

My car is at the performance shop having a stage 2 Roush TVS installed. The owner drove the car and noticed not only the 3.73 while, but also some interesting noise. Ended up needing bearings throughout, and had metal shavings evident. Since he was there, I decided to go to a 3.31. I can't wait to get my car back. The blower will be fun but I am expecting better drive-ability with the 3.31 gear change too!

 

[pufferfish]

The car was useless in first before.. even with DR's.. 7600 rpm is like 42mph with my tires and the 3.73 and the crazy mt82 first gear. now, when i come off the light i can actually use first - sure if i try to launch hard it still melts down the tires but at least i have a first gear now. second is the same way, under 3500 its usable, over 3500 its simply not and you need 3rd to put down power.

mods are simple.

cj cams, boss heads, cj intake and tb. stock GT short block with mmr gears. makes 489hp 413 tq on a mustang dyno. i gained 41tq from the boss mani setup, combined with a retune of my cams by Shaun. i shut it down at 7400 on the dyno to save it. there is no peak in the curve, its still gaining HP at 7400.

are you shitting me?! you managed to keep over 400ftlbs of torque with a cj mani AND cj cams AAANNNNDDD did it on the "heartbreaker" mustang dyno? that by itself is friggin voodoo stuff. it just kills me you aren't able to see where peak hp would be!

can you send me your dyno graphs? i have been dying to have boss mani rpm with gt mani torque. adam at rev aout said its not going to get there with the cj mani, but maybe its cams that makes the difference?

 

[pufferfish]

saw your video on youtube when i searched. the answer is E85...bummer. Its not a viable option for me.

 

[twistedneck]

E85 didn't do much. i actually lost a touch of HP with E85 even with 2 degrees of timing and a touch leaner lambda. The biggest changes from 372 torque was the intake, tb, cai (drew), and Shaun's retune of the intake cams.

I've attached the final overlay showing the difference before and after cam tuning.

http://checkja.com/images/dyno-aed-vector.jpg

 

[Voltwings]

I'd say Shaun knows what the hell he's doin with these CJ set ups. I raced my friends Boss last night and was dead even with him on the hit (which is the only part we'll focus on since we're talking about torque) and i feel this tells us a few things.

*Granted there are many differences, our cars are both essentially "fully bolted" with shorty headers.
1. Both cars have the same(ish) style manifold, so both should be at a torque deficit, with it being known the CJ has a slight edge.
2. His 3.73 gears put him higher in the powerband than my 3.31's on the hit, so i would essentially need more torque to match him

from 2nd gear 45 and 3rd gear 60 though, we were both dead even. I suppose the real test would be a 3.31 or 3.73 gear GT to really see...

Edit: Actually, now that i think about it... Wouldnt a longer gear lead to more load, AKA more torque? Dont we see the same thing going from 3.31 to 3.73?

 

[twistedneck]

My car is at the performance shop having a stage 2 Roush TVS installed. The owner drove the car and noticed not only the 3.73 while, but also some interesting noise. Ended up needing bearings throughout, and had metal shavings evident. Since he was there, I decided to go to a 3.31. I can't wait to get my car back. The blower will be fun but I am expecting better drive-ability with the 3.31 gear change too!

331 with 600+ HP you are talking power what tire size?

 

[twistedneck]

I'd say Shaun knows what the hell he's doin with these CJ set ups. I raced my friends Boss last night and was dead even with him on the hit (which is the only part we'll focus on since we're talking about torque) and i feel this tells us a few things.

*Granted there are many differences, our cars are both essentially "fully bolted" with shorty headers.
1. Both cars have the same(ish) style manifold, so both should be at a torque deficit, with it being known the CJ has a slight edge.
2. His 3.73 gears put him higher in the powerband than my 3.31's on the hit, so i would essentially need more torque to match him

from 2nd gear 45 and 3rd gear 60 though, we were both dead even. I suppose the real test would be a 3.31 or 3.73 gear GT to really see...

Edit: Actually, now that i think about it... Wouldnt a longer gear lead to more load, AKA more torque? Dont we see the same thing going from 3.31 to 3.73?

i'm sure the cj intake is worth more than the heads.. not heads and cams though.. both cars making power so your 3.31 was reducing the applied torque to the tire his 2nd was shorter than yours... his advantage until you go for top speed. extra resistance i.e. taller gear does make nitro and turbo cars perform better due to the boost building and dynamic cylinder pressure.

 

[dead man walkin]

Ok. With nearing 500 hp at the tires I understand moving from a 3.73. Stock the 3.73's are awesome. Mild bolt ons like I have and tires 3.73's are still awesome. Nearing 500 that's time to move gearing. I still feel a 3.55 or 3.31 would be a better choice but. I've never felt the torque curve with boss heads and the cj intake. And cams... my car wakes up at 3,000 and above. If yours is south of that yeah. You'll roast tires. Nice set up

 

[twistedneck]

Ok. With nearing 500 hp at the tires I understand moving from a 3.73. Stock the 3.73's are awesome. Mild bolt ons like I have and tires 3.73's are still awesome. Nearing 500 that's time to move gearing. I still feel a 3.55 or 3.31 would be a better choice but. I've never felt the torque curve with boss heads and the cj intake. And cams... my car wakes up at 3,000 and above. If yours is south of that yeah. You'll roast tires. Nice set up

with the boss setup and the old 85mm tb, jlt intake i made peak toruqe starting about 3600 rpm.. although the new intake / tb / cai has a higher torque number at those same rpms, it does not get to its torque peak zone until 5000 rpm now. torque also holds until about 6200 before dropping off vs. 5600 w boss setup.

 

[Highway Star]

[AndonTE]

I don't know how a boss is doing 180 miles an hour in 1 mile. if so they're definitely not doing it on 3.73's because I'm turning out 522 rear wheel horsepower at 7800 rpm on 3.73's & a 28 inch tire And I'm topping out at approximately 165 miles an hour.

I did the Mojave Magnum and within approx 1 mile I hit the Rev limiter in 5th and the car stalled at that speed for a couple seconds and I cruised in at 149 just under the 1st timers 150 my limit.
Second run: I pulled to 7700 in 5th (approximately 160 ) so rather than manage the Rev limiter for a half mile, I put her in 6th at 7700 and it felt like 6 fat chicks jumped in the trunk. I pulled across the one and a half mile mark at an embarrassing 159. You want to go 180; at the very least you need 3.31s. Better would be a Tremec with 4th 1/1 and 5th at around .81. The drop between 5th and 6th in a MT82 is too much.

 

[69camaro...]

why change gears, change your tire size and type. Gear swap, tadaaah

 

[twistedneck]

I could not be happier. the car is much more fun to drive and a lot more capable above 100mph.. I stomped a Tesla S pretty easy winding out 4th going into 5th gear.. he was pissed! and that car did look good.

However, i paid the price last night got popped going a little too fast and now i have a court date. live and learn.

 

[twistedneck]

i totally agree Highway Star - and the Boss that did 180+ mph in the mile i think was wbt, and he changed gears iirc and had a larger tire. i think he hit 7800 rpm like you.. my car would throw a rod at that rpm in the long mile distance and long time at w.o.t.

 

[kingnut]

315 would be nice for 700+ WHP. i think 331 would do just fine for 700 and under. my 373's were a beast NA.