800+rwhp 13B PP

[forcefed7]

Originally Posted by RETed

Actually, the video label says semi-PP, so it's not a full PP...

Am I the only one disappointed with the *torque* graph?
Although the X-axis is not labelled in RPM's, if we assume 4.10 rear end, standard gearing on a stock FD trans...looks like 5th gear pull?

Assuming tires are close to stock rolling diameter...
2,000 = 50mph
3,000 = 75mph
4,000 = 100mph
(Wow, works out nice for 25mph per 1,000RPM's?)
5,000 = 125mph
6,000 = 150mph
7,000 = 175mph
8,000 = 200mph

Assuming + or - 500RPM's due to different tire size, etc...
Peak torque ~4,800RPM?
Redline ~7,100RPM?

Torque drop from peak torque to redline just about 100 lb-ft???
Something doesn't jive...
With the semi-PP, I would think the peak torque would be a lot higher?
Also, the torque drop wouldn't be as drastic with the semi-PP?
20% drop in torque over 30% of it's rev range (actually more like 50% over it's usable rev range) is a lot to me...

Am I way off base here???


-Ted

Hey Ted,

The torque curve looks strange because of two things.

-Tire/clutch slippage when the vehicle comes into boost

-Boost dropping off at higher rpms.

Dyno runs were done in 4th gear using a stock FD trans. Tire circumference is about 79"

The graph in the middle shows calculated gear ratio, this line is fairly straight if there is no slippage. Peak torque output is actually in the 530-560 range.

The bottom graph is the boost, near the end of the run the boost is only about 28psi. The wastegate being a 66mm unit with a 12-13 psi spring has a lot of surface area, and once you get up in the higher revs/power output the exhaust back pressure starts to go a little over 1:1 and pushes the valve open, limiting the boost.

If you were to calculate the average acceleration rate (now that you know the engine rpm) I don't think you'd be too disappointed