GTM 370z supercharger 550bhp/400 ft of Torque: The Masterpiece
 

Firstly let me just say that from what I have seen on here for the past 18 months, I'm a big fan of GTM.

Just 2 questions out of curiosity in relation to the car in these videos.

1. Why was there no build thread for this car?
2. Why have these figures not been repeated on other stage 1 builds?

YouTube - GTM 370Z SUPERCHARGER 550BHP/400 FT OF TORQUE 460 RWHP 360 RWTQ.THE MASTERPIECE

YouTube - GTM 370Z SUPERCHARGER STG1 8PSI 550BHP/400 FT OF TORQUE 460 RWHP 360 RWTQ. TEST DRIVE

I would be happy to address your questions.

1) There is in fact a build thread for that exact car: http://www.the370z.com/forced-induct...s-release.html

2) This was part of the R&D process. Those numbers were made with a one-off race intake, GTM 2.5" cat-back exhaust and STOCK CATS. It is also an extremely aggressive tune on 93 octane gas. Mainly this was to demonstrate the supercharger's capability. Our off the shelf tune is conservative to ensure that everyone that buys and installs it will be able to achieve the advertised 500bhp (or very close to it depending on many variables) without undue risk to their engines.

The other main reason why we are showing such a graph is because we were able to achieve those numbers with this supercharger unit. Also, this is a strong validation that the supercharger unit is capable of more power with a better tuned VVEL tuning solution.

Here is the same supercharger unit making 490whp on a 350Z (VQ35HR with tuned dual CVVT) with 100 octane gas:


This shows very clearly how VVEL adversely affects power output with a supercharger. I cannot overstate that enough.

Again, we were able to make 460whp on the 370Z with STOCK CATS. The reason for that is because, quite simply, the back pressure generated by the stock cats keeps air from blowing through the engine. This means more air stays in the cylinder to be combusted. Once we are able to tune VVEL, we will be able to reduce the overlap and thus make more power on supercharged cars.

Thanks for the quick and detailed answer, much appreciated.

:bowrofl:

i need one :)
is there a kit ready for shipping :D

And probably NA too.

How is the progress coming on this project? Any updates? :tiphat:

We are making great progress so far, Also we are applying everything we have learned from stage 1 to the stage 2 so we can utilize all the 91 potential. The 91 supercharger has been on and off the car hundred times do far. It is a very time consuming process ...

Sam

Any estimate on a release date for stage II?

I've got the money just burning a hole in my pocket!!

We should be done by the end of this month, FYI we could have been done much sooner if we stuck to just fitting the bigger charger instead we are focusing on maximizing the potential of the 91 with this engine .

Sam

Thanks for the update. If I recall correctly that's about when you said it would be done when I spoke to you a few weeks ago.
I have no doubt that you are going to make sure it is the best it can be.
I wouldn't want it any other way.

Once it is released, how long will it take to ship from when the order is placed?

We are hoping right away, We already have a good size list of people that have prepaid and have been waiting for a while for the stage 2, so those order will be shipped out first.

Sam

:yum:

Reading this thread makes me want that Stg.2 even more than I already did :yum:

Waiting for the stage 2. " by the end of the month ?" Thats the best news i have heard yet. Can not wait to take it down the 1/4 mile.

Can someone with engineering knowledge give a layman's explanation of how the VVEL hinders the power output and how "tuning" it will benefit both NA and SC cars? I have a vague understanding of it but I know VVEL tuning and "cracking" the ecu has been a hot topic

I've posted an explanation on another thread, can't find it... here's a brief copied and pasted explanation.

The VVEL system in our cars and extremely aggressive at about a 300 cam duration;

Valve Overlap

"The portion of the operating cycle of a reciprocating engine in which, when the piston is passing TDC (top dead center) on the exhaust stroke, both the intake and exhaust valves are open. Valve overlap increases the efficiency of the engine operation by allowing the low pressure caused by the exhaust gases leaving the cylinder to help the fresh charge of fuel-air mixture in the induction system to start moving into the engine."

When you're pushing so much air into a car (forced induction) with an aggressive cam - there's air that isn't going to be used and is just going to pushed out of the motor and wasted because both the intake / exhaust valves are open at the same-time. Drop the cam duration, you'll have more time between the valve overlap process so when the air enters the head it will give the bottom end enough time to use that air for the combustion process, building more psi, creating more power.

Let me know if there's anything I'm incorrect about, but that's what I've gathered.

So in essence a more free flowing exhaust system could effect SC performance if you are using the VVEL system. That could explain some weired results we've seen in SC'ed cars so far.

So then, LTH/TP + SC + VVEL <<< LTH/TP + SC + 'cracked' VVEL??

I get it now. These were tested with stock cats. More resistance to exhaust flow = more time in combustion chamber = best you can do with SC + VVEL. Sorry I had to write that out. Went to an engineering school but was not an engineer. Pretty much exactly what Mike said post #2.

The supercharger runs off of backpressure, that's why more boost / power was made with the stock cats rather then longtube headers, reduce backpressure lose boost.

they don't run off back pressure, to much is still a bad thing as then you start to trap exhaust in the cylinder instead of more fresh air mixture. the breathing mechanics are complicated. basically what you want is enough duration and lift on the exhaust that the engine pumps out most of the exhaust gasses, but on our cars which are tuned for n/a the valve overlap between the exhaust and intake valves allows the now compressed air charge to escape with the exhaust before the valve closes. all that is really needed is to bump the intake cam timing backward to reduce the overlap but with vvel you have to do both or nothing or else you risk the valves hitting the piston due to the high lift.

sounds like you need new cam shafts all together with the cam lobes in different locations specifically customized for each individual car's set up. :eek:

Not with the 370z...the cams are essentialy tunable themselves just waiting on the good-ol-boys at GTM to finish crackin te system for it. CANT WAIT!!!

only the intake cam has VVEL

One "off custom intake ".
how can you claim those #'s with that intake, as the average customer will not have one on his car.
How much more did it make VS the stock intake ?

Read post #2

wow, someones neurons are firing. I thought all hope was lost.

In the end of it all, the real gains from F.I. be it SC or TT on the VQ37 will not be recognized until VVEL is cracked its that simple. When you are forced to deal with stock cats due to VVEL not allowing you to fine tune timing and fully utilized the compressed air you're just banging around fixing everything else except the real issue. Damn thing is that VVEL seems like a tuning rubix cube that no one has figured out yet but everyone says they are working on.

Until then... you have to find ways around it, safely.

^^that's a bandaid solution. Fact of the matter is that none of us really know what the VQ37 is capable of until VVEL is cracked. This is a guess but since its going to take a lot of r&d and probably not be something as simple as an UpRev add on I'd guess its going to be expensive. Kind of sucks for guys like me who already bought the uprev and then have to go back and get either an upgraded uprev if that turns out to be the solution or pony up for an additional tuning solution and/or hardware all together.

GTM just shipped my stage 2.
Will be here in about 10 days ( has to clear customs ).
the wait is over.

Congrats dude. Looking forward to finally seeing what your car will put down at the strip.

Just started reading the shipping manufest with my GTM stage 2 kit and it says
super charger back ordered and not shipped.
SAM WHAT IS GOING ON.

PLEASE TELL ME WHY !!!!!!!!

I thought you got it already.

Ouch ... That is so cruel for GTM to do that. They could of least gave u a call or email. You know ... That communication thing ....:stirthepot:

Steve, the pick list should have a note that the supercharger in is the second box, We could mot fit the coolers, meth kit and the sc kit in one box .

Sam

Sam called me at home tonight. And is calling the the shipping compamy to find out what happened to the second box which was shipped the same day as it would not fit in the one big box which i recived.
He will call me by 10.00am tomorrow and if its lost he promised me that he will make good on getting one to me.
ASAP.

Z

So let not jump on him for he gave me his word that it was shipped and is following up on the tracking #.
Once he heard there was a problem he called me at home sunday night with in an hour to take care of the problem first thing tommorrow morning.
Good customer service.

Z Eliminator

It has been resolved.
no issues .

Z eliminator

^good to hear

So when does the beast awaken?

Wow -- awesome!

Other than the TC and trans cooler, are you building the rest of the trans or leaving it stock for now?