What are your opinions on it. I am seriously interested in it but lately I am hearing more and more negative like not having a linear powerband and it being very noisy. In a good or bad way? Just voice your opinions on it as a whole. Thanks!

 

define "linear"

i'll let other people field these questions cause I probably answer them once every other day, but my conclusion is this:

every FI kit sucks in at least a few ways

and I think the vortech kit is fine

 

somw people complain that centrigual SCs don't make alot of torque, but when you are getting on it, what rpm range are you most likely in? 5000-7000. that's where mine is due to the close ratio tranny in our cars.

if you race a turbo car from 3000, you'll lose. BUT, why would you start a race a 3000 rpm???? you won't. he won't.

Another interesting thing to look at is the dyno graph of most turboed Gs and Zs. The power seems to drop off significantly at high rpms. WHY??? I have a feeling that it may be due to too much exhaust restriction in the turbo manifolds and piping to the turbine housing. It seems very strange. Let me try to locate some of those dyno graphs.........

 

here's one:

http://us.st11.yimg.com/us.st.yimg.c..._1901_93928177

tHis graph is froma greddy kit. his power curve is plateauing at around 5500 rpm. I have seen other greddy dynos like this, too.

The dyno graphs on the JWT kits that MRC is doing seem to follow the natural powerband of our cars. Maybe the JWT is better design. not sure, I've never seen it.

 

here's a TN kit:

http://www.my350z.com/forum/attachme...6&d=1152318592

It is just very odd to see a huge shift in the power curve like that. by 5700, the power is falling off quickly!!! Why is there so much loss in the upper rpms. That is where these engines are designed to be efficient. My only thoughts are that it must be a huge restriction on the exhaust side of things (between the heads and the turbine housing.)

 

here's a typical vortech graph:



It just keeps on pulling!

I have had 3 turbo charged cars over the years, and I have had 2 centrifugal SC cars also. The feeling is very different.

The turbos are fun at part throttle , mid rpm jabs at the throttle. lots of torque. turboed AWD cars are really fun. I used to have a Typhoon. That was awesome. jam the brakes, spool the turbo, and launch! ( of course, I got an equally impressive launch by putting nitrous on a V8 AWD explorer )

The sc'ed cars are much easier to modulate the power, more predictable when getting on the power (especially in curvy driving!!) THe SC cars are fun, too because you don't want to shift. They just keep pulling harder and harder and harder, the higher you go in the rpms!!!!

 

another reason the torque plummets is becuse it's a fixed PSI.

actually the boost hits peak boost at around 3500-4000 rpms usually, then will gradually drop as it hits redline - a small drop as in only losing 1 or less PSI from 4000 rpms to redline

a centrifugal on the other hand keeps increasing boost so you end up with a very very flat torque curve from about 4500 or 5000 to redline

 

sentry, if the psi is fixed, the torque curve should mimic stock stock curve (once the turbo(s) are fully spooled up) only at much elevated levels. What I see in alot of the turbo graphs looks like a choking point in the exhaust side of the engine at high rpms.

Do you have a graph of your power curve? it would be interesting to see!!!

 

yeah single turbos are really choked up top

the midrange is still where the engine is the most efficient. High rpms is always never as efficient as where the peak torque is - this is why VTEC works pretty well cause it makes the engine suddently more efficient at high rpms.

I'll have to find one of my graphs and post it

 

the log-style manifolds on the greddy don't look too hot either.

here:s a nice looking turbo header!!!!

 

Most of the kits do use a manifold like that... Logs allow for quicker spool times.

 

hehehe.... That is My DynoComp Dyno


Needless to say I LOVE MY VORTECH

Check this clip out


http://s24.photobucket.com/albums/c4...G35vs350Z2.flv

 

I love my vortech. I think the power was suprisingly linear when I first got it.
I do have to say it is kind of loud but you get used to it real fast and then its addicting.

 

how many of you are using the stock pulley?

what out the oil return? spacer or tap the block?

 

I've owned both. I've replaced my Vortech SC with a Greddy TT. There is no comparison. Turbo is by far a better product. Low end torque is incredible!! The Vortech was as loud as hell and sounded like a cement mixer. Turbo is nice and quiet until it spools and then sweet music!!

Of course you will get people with the Vortech kit defending their expensive purchase. This is to be expected. I used to defend the SC as well.

I suggest that you contact companies that install these kits and get their opinions. I would predict that the majority of people who had a chance to compare the two would choose a ST or TT over a SC.