How in the hell are stock twins making over 400 whp? lol

More than power, I mostly bought a single car with a v-mount because I didn't want to have to deal with the complexity of the stock twins or the inadequacy of the stock cooling system.

The car was actually tuned very conservatively (11.6 psi) to keep things from breaking.

 

Pretty crazy power with just bolt ons/porting.

Tom ran 10.8et in the 1/4 mile too!

https://www.rx7club.com/time-slips-d...turbos-954861/

 

22 psi... that's a lot, right? lol

I kind of figured porting was involved.

My low-end torque is so bad I wouldn't even dream of porting. I practically have to floor it to get it loaded on the transporter...

 

harder you push those stock turbos, the shorter they will last.

 

Put this cammed 436rwhp LS2 dyno in-




With the stock M12 T56 gearing and stock (this was 6.0 GTO) 3.46 rear you can see the torque at the wheels is really low.

But, in auto-x (2nd gear) the LS2 would have better acceleration than the rotaries in 2nd gear from 65mph to 70mph, but it is really getting worked over under 65mph.




I did the LS2 with T56 and 3.9 rear to give it more torque.

For auto-x 2nd is now too short ending at 60mph, but you could extend revs to 7krpm if you threw some valvetrain in there when you did the cam and ECU tuning. Probably still too short and you would have to use 3rd gear too.

Good news is now the LS would accelerate better 45mph to 60mph than the rotary and at no point does the stock twins make more torque (single is still making more torque under 45mph and then again over 60mph, but hey that **** is going to blow up soon.) Of course 60mph to 70mph now has much less torque than either rotary because 3rd gear.




Now I see why the V8s hook up so well in 1st on slicks at the drag strip- they have much less torque in 1st gear!

 

I'm loving these Torque at wheels charts. I imagine 3.9 gears should let the single turbo rotary deliver more power to the ground between 30-70mph than the other two setups, assuming you don't get stuck needing to shift into 1st on low-speed corners.

 

Hey Ian, wanna post up your 7670 with a 4.56 FD ratio and 23.75" or 25" rear tire height and see how the overlay is? :P

 

Not sure exactly what you want to compare, so here is a variety.

Here is the
419rwhp EFR 7670 w/ S5/S6 USDM trans & 4.10 & 25" tire in Black
419rwhp EFR 7670 w/ S5/S6 USDM trans & 3.46 & 25" tire in Orange
436rwhp Cammed LS2 w/ M12 T56 & 3.46 & 25" tire in Blue



Here is the
419rwhp EFR 7670 w/ S5/S6 USDM trans & 4.10 & 25" tire in Black
419rwhp EFR 7670 w/ M12 T56 & 3.46 & 25" tire in Orange
436rwhp Cammed LS2 w/ M12 T56 & 3.46 & 25" tire in Blue



Here is just the
419rwhp EFR 7670 w/ M12 T56 & 3.46 & 25" tire in Orange
436rwhp Cammed LS2 w/ M12 T56 & 3.46 & 25" tire in Blue


As you can see, the higher rpm you can make torque the more torque at the wheels with gearing.

That is why Horsepower is the factor affecting acceleration (Horsepower is simply a function of Torque and RPM).

 

Here is an interesting one.

P.A.R dog gears in FD stock case with 4.77 final drive.



Doesn't alter max acceleration line much at all (that is an arc drawn along the outer Right side of graph), but it would be very forgiving for what gear you are in (lots of torque overlap).

 

Basically, for optimum acceleration, you should shift when the wheel torque in the current gear drops off to match the wheel torque in the next gear.

And that will definitely change based on modifications.


I've seen very few Dyno charts that showed an engine that should be shifted at 9000rpm, power drops off too much that high.

 

agree completely.