Z_U_NVYN

iTrader: (1)

Here's some numbers from an old thread to give you an idea of what system gives you the most gains in RWHP + torque. I am in the same boat as you in my decision but Jason @perfromance said either to get the Stillen(heavier than stock) or the NISMO. I was leaning towards the Borla but now....I don't know anymore:

Borla (car 2) = 8.2 Hp - 2.7 ft/lbs torque (peak values)
A top end system. Little HP increase until the 5600 rpm to 6500 rpm range. Lost HP & torque below 1800 rpm. 60mm (error actually 58mm). Weighs 52lbs. 1 million mile warranty. Installation - Hard (17 pieces)

5Zigen (car 2) = (-3.4) Hp - .02 ft/lbs torque (peak values)
Lost Hp, no real torque gain. Most expensive. Loudest. 58mm pipe. Lightest @ 25lbs. 1 year Warranty. Installation - Medium

Stillen (car 1) = 8.1 Hp - 7.3 ft/lbs torque (peak values)
Hp and torque increase starting at 3000 rpm to redline. Lost a little HP & torque below 1800 rpm. 60mm pipe. 74lbs - 10lbs heavier than the stock system. Lifetime Limited Warranty. Installation - Easy

Injen (car 1) = 7.6 Hp - 5.1 ft/lbs torque (peak values)
Small torque loss at 2800 rpm. Torque gain starts at 3300 rpm. Small Hp increase starts at 3300 rpm, max Hp from 5800 rpm to redline. Major loss in Hp and torque below 2200 rpm. 49lbs.
1 year Warranty. Installation - Easy

Nismo (car 1) = 6.3 Hp - 4.5 ft/lbs torque (peak values)
Torque increase starting at 3000 rpm. HP increase 4800 rpm to redline. No power losses below 1800 rpm. 54lbs. 3 years,
all this is from the sport z dyno tests a while back

Z1 Performance

iTrader: (564)

that 5 Zigen was a preproduction piece IIRC

my points were made exactly though 0- if you think you can tell the difference between a 6.3 hp gain and an 8.5 hp gain, more power to you

go for what you like the looks and sound of

zectasy

iTrader: (2)

its a hard decision but as of right now im leaving towards the one that i think looks the best...which is the rsr...it seems like a 2-3 hp difference is not gonna make a difference

mdmike

Has anyone looked at this Muffler? I saw it on 2 guys garage and it looked pretty good.
http://www.aero-turbine.com

Might be a bunch of hype.

adanande

5 zigen pro racer x tube and the new JIC dual branching exaust that is compatible with the y-pipe thats it, but I will not get either untill someone builds a rear diffuser assay that will emulate or exeed stock specifications for drag reduction. i will vounteer my car for R and D please someone make me an offer, i will donate my ar to make a diffuser, that will mean i can buy and exaust, % zigen pro racer z tube. 30 horse power to the wheels with reprogram. also I would nee tilton flywheel to say goodby to the new 350 hoserpower supra coming out. " I am not afraid" of Supra.

Z BOY

iTrader: (41)

Is "downpipe" the same as headers?

zectasy

iTrader: (2)

downpipe is usually something associated with turbos and what not...usually its like the cat right before the header...a big restriction on turbo cars..

PoWeRtRiP

wth are you talking about plz enlighten us on this 350 hp supra


why do you need a diffuser on the exhaust to make drag coefficients similar to stock? do you race pro or commonly exceed 100mph?

30whp would be nice but be wary of some of the claims that you hear about performance numbers. all the exhausts out there are basically the same why would one get so much more than all the others?

UsafaRice

I bought that copy of Hyper Rev while I was in Japan a while back and read through the article. It's buried somewhere right now because I just moved, but the dyno refered to is not the manufacturer's (Powerhouse Amuse) but Hyper Rev's. It was close to 30 HP from what I remember. They actually tested the straight pipes as well as the 2 different Y-pipes that are used for manual and automatic cars.

Resolute, if you lose exhaust gas or intake charge velocity, you will lose torque. This is part of the trade-off in "shorty" vs long-tube headers. It is a tradeoff that is made on turbo cars with huge exhaust setups to make lots more power higher in the RPM range. And finally, if you hog out your ports (intake or exhaust), you're going to get lazy flow and then engine will lose power down low. I guarantee you that if you yank your exhaust system from the headers back and leave it off or replace it with 4" or larger tubing, your Z car will not be driveable on the street. I would pay money to see a dyno done like this.

You are correct about the backpressure. The only thing back pressure can do is close the exhaust valves faster. Each cylinder contributes a single pulse of exhaust every 2 revolutions. The trick with very well designed headers or an exhaust is to time the convergence of these pulses so that flow and velocity are maximized.

Resolute

iTrader: (2)

well.. you're half right. It is all about velocity, as you said, but the key to making power in a given rpm range is resonance. The exhaust pulses' velocity can be increased by tuning the pipe diameter to the speed and mass of the exhaust passing from the exhaust valves to the ideal resonance, this increases the velocity of the pulse by creating a strong vacuum behind it which helps scavenging in the combustion chamber, as well as drawing in intake charge during overlap. Various diameters of exhaust pipe, like headers, and length of the exhaust pipe, like shortys, change the ideal frequency of the resonance so that it will be more effective at certain rpm than others. This is the myth that a smaller exhaust makes more lower-end torque by increasing back pressure. The fact is, without any exhaust at all after the manifold, there is extreme backpressure from the gass being expelled in a disrought manner. With a small exhaust after the manifold, the gass can be expelled in a higher velocity with the peak velocity being at the key resonance point for the exhaust pulses, but because of the diameter and length, will usually be at the lower rpms. With a larger, shorter exhaust after the manifold, velocity will still be higher than with an open manifold alone at low rpm, but again, the increase in velocity will be greatest when at the key resonance for the larger size and increased number of exhaust gass pulses found at higher rpm. The higher the number and larger the pulse of exhaust gass, the larger and shorter the pipe to achieve the key resonance that will increase the pulse velocity. Take a look at a pipe organ, it is the same concept. Changing the diameter and length of the pipe will change the velocity of the air charge moving through it. In every case though, it is about designing a system that maximizes velocity at certain rpm to improve power, whether it be at 3000rpm or 13000 rpm.
The same concept goes for headers as well. As for turbos, there is no such thing as a tradeoff to make power in the higher rpm range that has anything to do with the exhaust. The power curve on a turbo car is the result of the turbo, not the exhaust. All one can do with engine breathing mods is improve the upon the inherent size and design of the turbo, but not change the charecteristics of it. Make an engine breath better and the turbo will make more power, but in the same range as before. The only way to change that is to change the turbo's specs. As far as resonance goes with a turbo, it is generally not a consideration. Find the biggest damn exhaust you can and put it behind the turbo. The only serious consideration is made to the manifold design, so that each individual exhaust pulse can enter the turbine individually if possible. This is done to slightly improve lag, not boost threshhold, but lag, and is accomplished via a split turbine inlet design and manifold runners seperated by firing order.
And a downpipe is the portion of the exhaust attached to the turbine outlet that leads to either a cat or muffler, or just an open pipe used as the rest of the exhaust. Since the engine's exhaust pulses get whipped to hell by the turbine, which naturally increases backpressure, the downpipe and ensuing exhaust need be as large as possible to ease the resistance the turbine has to evacuate the gasses against.

Resolute

iTrader: (2)

Check out www.nissanperformancemag.com, IIRC, Kojima's got an article on this that is explained in pretty hefty detail. It might also be on www.Sentra.net, he writes some articles there as well. If anyone's really interested.

GY-Z

so u back from jap?
any news on the amuse dry carbon door and hatch?

UsafaRice

No, I'm in North Carolina right now. The trip to Japan is during August and September. Don't worry, I'll have pictures and all the info I can find!

GY-Z

thanks agian then!

sausage5000

omg the z's instead of s's thing is so annoying.