whoa you are right! i miss read the dyno plot at first thinking it was the blue line that was the "after" run but in fact it was the "first" run. there is a considerable amount of meat lost between 3750 and 4500 rpms. this WILL hurt when shifting up a gear from redline as it would bring you right into this range. it really does take off after 4750 though. that's why i think it would be perfect if the redline was increased to 8200, like the gt3, so an upshift would put it around 5000

SEE, it's from plots like these you can get valuable tuning data. even YOU looked at the graphs .

 

maybe you mean you shift TOO SOON. that would bring you into that torque dip.

 

you gonna keep it a secret then? please tell us how Dog can minimize the TQ/HP dip before 4500 AND kep the TQ/HP beyond 4500.

what the correct setup?

 

Hehe with that light weight flywheel and smaller pulley somehow I think you're doing more than alright Perhaps a strict diet for the car is in order:P

 

depends on the application. like you said earlier, if you keep it about 4500 then everything is dandy. so for your average street light drag race this is not good but for the track this IS a good increase.

 

smaller pulley? LWF? i don't know what you are talking about .

diet sure. i can lose about 25lbs around the midsection

how the hell can you lose weight in the rear? i went with the composite decklid and that helped but throwing on the SC did not. i can go muffler bypass but it's too loud (dreaming up a prototype bypass/muffler combo though). i guess i can get a carbon hood but it'll make the car front end light. hmm... i can get rid of the sunroof and cover it with a carbon top.
ya don't think i've been thinking of it, do you?

 

Had to go do some road testing. My 1st to 2nd shift at 7k rpm puts me right at 4.2k rpm. Certainly in the soft spot of DDogs graph. Couldn't this be compensated for with a LWF to minimize time in that soft spot? Also, isn't performance gain (on a dyno graph) gaged by the increased area under the curve?

I already have some softening of the lower rpms from the my gheto fabspeed copy airbox.

I'm very curious to see how the header will affest my NA car. Might even have to make a b4 and after dyno apt. to compliment the road tests.

 

The loss of bottom end will be even greater in an NA engine. The result will be the same as if you increased the valve lash in the engine. With the more free flowing exhaust you will have a smoother feel to the car and better breathing at the higher rpm's. Even though it won't perform better in the lowend this setup is sometimes more fun to drive as you have a longer time range in each gear. Best way to get your second gear into a better part of the power band is to replace your first gear with a taller gear. First gear in the 996 is the weakest part of the drivetrain. IMO.

 

You got me curious and I just had to know; so I went out for a short drive. I needed to get some gas anyway...

I ran it about 5 times, full throttle from first to second and second to third. I couldn't safely go any faster than that.

I'm not sure if the gearing or the software is different on the 3.6 liter, but when I shift I'm consistently at 4.9 or 5K rpm's every time I engage the next gear, going from first to second and second to third.

 

These headers were designed for the track. He goes to Sebring quite a bit. He had them tuned for what he thought would be beneficial on a road course.

 

If you shift at 7300 rpm from a gear that is 3.82:1 into a gear that is 2.20:1, your engine speed drops to 4200. If you shift at 7200, your engine speed is only 4150. You cannot go by your tach reading as it cannot adjust fast enough.

Take you car slowly up to 7300 in 1st gear and note your speed. Then take the car up to that speed in second gear and note your engine speed.

Software plays no part in this fact.

 

The headers for Suncoast were designed for a gain in the mid range and with a better top end charge. This will help exit speed and top speed. Also, they were not just tested on a dyno, but the drag strip, comparing mph #'s which show realistic on the road gains. As 1999 Porsche 911 stated above, the rpm drop from 1st to 2nd will put the engine torque in a not optimum spot. HOWEVER, this is not true in the higher gears. The gear spaceing will tighten and better optimize that header under real racing or high performance driving. Also, very little real time is spent in that area under accel. Because of the low speed, gearing and aerodynamic drag the car moves through that rpm quickly even though the power is down very slightly. The 2nd to 3rd and 4th to 5th shift will show a much smaller rpm drop and put the power in the sweet spot. this is where the gains really start to shine. If your driving on a road course or the drag strip and you data log where the engine spends most of it's time you will likely find it's above 4500 almost the entire time! So, under full throttle conditions those headers will out perform the stock headers everytime. The car WILL be faster than the stock setup. I think this is what we're all looking for when we spend our money?

Joe R

 

did the same test today.

from 1st to 2nd rmp dropped to ~4250
from 2nd to 3rd rmp dropped to 5000.

anyone know what the reprogrammed redline is for the evo SC? seems like it goes to a soft limit around 6750~7000 in first gear. definitely doesn't go to stock redline in 1st.

 

so hey, what is your MAGICAL setup? really interested.

 

I'm damn ignorant about closed loop systems, but on my sport bikes (open loop) dips in the curve created by changing headers can usually be cleaned up by adjusting the fuel map. Is it not the same with our cars?