There is a lot of debate about whether the higher compression ratio significantly affects spool time. The short answer is, not really. The long answer is, higher compression will give you better off boost performance until you hit boost. Also the extra heat from compression causing additional pressure in the exhaust manifold to spool the turbo has to be significantly higher from a pressure ratio standpoint to make a significant difference, but that doesn't happen to that extent.

I agree there are a lot of technical mumbo jumbo that can be thrown around, but from personal experience going from the stock 10.3 CR on my 350Z to 8.8 CR on the built engine my butt did not notice any change in efficiency, boost kicks in hard and early breaking tires lose in 1st through 3rd gear and still scary in 4th

20G's are used all the time on the 350Z. We've run even larger turbos on the VQ37 VVEL, and I promise you spool up and powerband isn't going to be an issue. Keep in mind, all of these turbos kits are using very small T25'ish sized flanges, so exhaust gas velocity isn't much of an issue.

I would much rather take the larger 20G over the more restrictive 18G. Compressor charts only tell you so much, but power output and spool vary drastically based on the application you are putting the turbocharger on.

How do the more turbo savy people here feel about the 20G and its journal bearings? I'm no expert, but people have convinced be that ball bearings are always better for turbos.

Thoughts?

ball bearing is always going to be faster on spool up but is more expensive than journal bearing...it all comes down to how much more do u want to spend for minimal performance gains..ball bearing will give you more of a crisp spool

The spooling benifets of BB vs. journal are vastly overstated, IMHO. It's the size and structure of the turbo, and the displacement of the engine that has a much greater impact on turbocharger spoolup characteristics.

We just had a BB turbocharger on XKR's car take a dump after 3000 miles. Garret could not determine the cause of the failure. With Greddy, I have had modified turbos go bad, but haven't had any factory Greddy turbos go bad.

I am not suggesting that journal is more reliable than BB, but I am stating my experience to show that textbook discussions, can vary wildely from practical experience and application.

Sharif if people want a SC set up why argue? just build them one!

http://i524.photobucket.com/albums/c...ormance/SC.jpg

i agree i would personally rather have a turbo set up, but nothing wrong w/ a good supercharger.

Thank you for that reply!

anymore news or updates on these?

I'll second this as a current M3 owner now perusing a Z site...

just finished initial dyno tuning of the twin TD06-20G Tuner Turbo kit. 450hp 370! The test drive feels good too!!!

about 3 hours ago from web (Greddy Twitter)

Good find.

Here's more info about it: http://greddy-usa.blogspot.com/2009/...0z-coming.html

"On SP's dyno the base Tuner Kit with the optional pre-programed emanage Ultimate fuel kit and full dual 70mm Turbo Ti-C exhaust the Z put down a healthy 449.5whp! at just 0.45kg/cm2, on a conservative 91 pump gas tune.

Not only is it great on the dyno for a stock VQ37HR engine, but its also a great ride on the road. We have been breaking in our new GTR in stock form and we think this Tuner Turbo kit for the Z feels even more fun!"

Finally a video! I'm really liking how the FI market is panning out for the Z.

The Ti-C sounds mean :stirthepot:

Very good initial results. Sounds like they are starting to make some good progress. :)

Is 0.45kg/cm2 6-7 lbs. of boost?

Finally a full throttle video, and a Dyno sheet For a 370z TT :tup:

http://4.bp.blogspot.com/_1agu36yXDm...g_370Zdyno.jpg

I'm a great example of this...I liked the Cayman S (but it was out of range), and was in the market for a sports car. The Mustang GT500 was on my list as well - basically I was looking at 30K-55K. The Z came out...I saw the lines of the Cayman S in the car, and it's pricing starting at half as much. I can't imagine myself a Vette owner, or a BMW owner...

Modding it wasn't even in the picture, even when I bought it a few months ago - but, if a SC kit comes out, I may have to reconsider. It's a great debate between warranty coverage if something goes boom or, chasing that idea of having more power, or, leaving it all until my debts are paid off, which, including the Z, might be a couple years....which timing-wise, might be a good thing as all the kinks and bugs should be long gone by then and prices come down...lol...time will tell...lol

Yeah, not to mention the oil being used to cool the turbos themselves, and this car already had a tiny oil heat "issue"

A cooler would be manditory, if you happen to track the car, you might need two oil-cooler cores and chain them together.


one other thing I don't like about turbos is that you have to give them time to cool/spin down after driving so that they aren't screaming and their oil supply shut off, roasting the oil...etc.

I think the key is controllable power. One nice thing about SC's is that it's instant, both with on and off throttle - no spool up time (granted, turbos are getting better spool up times, but, still not as quick!)

I'm suprised at the Dyno graph.. with most turbo cars the tq. comes on real strong and then tappers out at the end. It looks like with the vvel it some how even with the turbos kicking in keeps the tq flat and straight.

It's changing the duration/lift - it makes sense in a way...it'd restrict the amount of boost the engine will allow in the cylinder...and the rest would be blown off?

That said, I don't like how the dyno starts at around 3.5K, and given that, it'd show a lower low-end torque.

heres a pic of an EVO X with upgraded turbo.. I was expecting the Z to have peak HP and TQ closer to the same numbers, with a kick your *** tq curve like this

If a turbocharged car has a flat torque-curve, it means the turbos are too small. :)

450 RWHP on ~6.4 PSI with I'm assuming only their turbo-kit, exhaust, and a tune is not too bad.

It sounds INSANE!

I think 6-7 lbs seems like a good spot to keep things tame enough for the street and still have a little added fun.

I found this pressure unit conversion tool and table. So basically, the Greddy kit is running 6.4 PSI, as some have already mentioned.

Pressure Units Online Converter

now we just need a price!!

Last time i spoke to the GM at greddy, it would be around $8900 retail

That's a :tup:good price

Not to mention that graph is off a dynapack so just lop off 10%

Awesome news! The Ti exhaust sounds tits and the results look promising. 450hp@6.4psi is pretty impressive with that torque curve. GTM pulled about 470whp @7.5psi on their TT kit but I dont recall what type of dyno. 500whp seems almost too easy on the VHR

Here is a picture of the engine bay from their Facebook group...
http://hphotos-snc1.fbcdn.net/hs242....4_686424_n.jpg

Another one from their Twitter...
http://img59.yfrog.com/img59/7079/uif.jpg

Agreed. My friend's GReddy TT on his G35 hauled *** at only 6lbs boost. Not to mention sounded like a damn rocket.

Latest images included. Note the Greddy BBK and Type-S suspension.

http://img27.yfrog.com/img27/6501/v92.jpg
http://img27.yfrog.com/img27/3579/p9du.jpg
http://2.bp.blogspot.com/_1agu36yXDm...og_GPP370Z.jpg

GTM or Greddy? Both around same price. Output close. Suggestions?

GTM! just my 2 cents though. Bigger turbos and much more room for improvement.

I don't think you can go wrong with either, IMO.

I'm leaning towards Greddy myself.

im also leaning Greddy, thoses Mitsu turbos just last so long.. i went through 2 garretts in 2 yrs compared to 1 Greddy 20g that lasted 3 cars and 5yrs and could be still going for all I know.