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      07-26-2013, 04:21 PM   #1
pokeybritches
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G-Power Z4M Initial Impressions

WOW. I was expecting good top end, but I'm totally blown away by the midrange torque. Even with 265 width Michelin PSS, I can light up the tires in 95 degree weather in 2nd gear. I can't imagine needing more power for anything other than bragging rights. 3rd gear is the first opportunity to go WOT without traction control heavily interfering... which will get you over 100 mph, and jail time in some states.

The car dynoed at 405 rwhp on 93 octane, with no WMI, in the central Florida summer heat. Once I get the graph from the shop, I'll post it up here. I'm very interested in seeing the area under the curve, because it doesn't feel nearly as peaky as my non-M Z4, despite an unmodified non-M reaching max horsepower earlier in the powerband. The S54 in NA form reaches max horsepower over 7000 rpm, and I guessed that a centrifugal supercharger would exacerbate this feeling. Not so. Torque is available immediately, in large enough quantities to elicit profanity from unsuspecting passengers.

Other mods include Supersprint V1 stepped headers, Supersprint section 1 connecting pipe with HJS cats (made by Custom Performance), and Rogue Diablo mufflers. I did not get a before dyno because the car was not stock when I brought it in, and the additional modifications would have influenced the horsepower delta. FWIW, a stock Z4M dynos around 265-275 rwhp, and 405rwhp represents a 50% increase in power to the ground.

I was surprised at how much sound the headers and race cats uncorked. I thought the stock car with Diablos sounded near-perfect. Now it drones unbearably, so I'll likely be moving to sport mufflers in the future. The burbles and pops on off-throttle cruising are fantastic, however.

Any supercharger noise is drowned out by the exhaust. The bypass valve makes a nice "woosh" when letting off the throttle over 4000 rpm, similar to a turbo BOV but less obnoxious. There is no abrupt jolt when rapidly letting off the throttle, unlike my other kit. Part of this may be due to the bypass valve.

The last thing I'll mention, and probably most importantly, was the way my shop (Precision Sport Industries in Winter Park, FL) handled everything. I have NEVER in my life dealt with a business that impressed me more. I'll go into depth with a later review. Between the consultations that saved me thousands of dollars; expertise I could rely on for setting the car up to my desires; excellent communication; professional attitudes; and HONESTY... I can't recommend these guys enough. They are the only people I know of that take better care of my car than I do when I work on it. Their patriotism and personal interest in military personnel were enough for me to fly a flag in their honor while I was deployed in Afghanistan. They don't sponsor me to endorse their shop. They didn't even ask me to write a review. I was there for a supercharger install, and all they asked for was very reasonable payment for a job well done. My car looked better when I picked it up than when I dropped it off. More importantly, it truly looks and feels like an OEM install.

More to follow! Until then, here's a teaser:



Edit 8/14/2013: I got the dyno from the shop, and unfortunately don't have AFR or rpm. If the run was done in 4th, it looks like I had a little bit of rpm left to go. I also found out the 405 rwhp was done with a different correction factor, and I'm looking at about 397 rwhp (SAE corrected). Still not too shabby for a run in the Orlando summer, especially when the kit claims 450 bhp! I plan to get another dyno done in the next few weeks.

Update 3/21/2014: After 8000 miles, the kit has performed extremely well. No stalls, CEL's, or oddities while driving. Full and part throttle response is perfect. My only issues have been tightening a hose, securing a bypass valve bracket that popped off, and a mild vibration in the cast manifold at idle. Full review coming next month. Peak boost is reached by 5000 rpm. The vibration in the video is from my work laptop in the passenger seat.

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Last edited by pokeybritches; 08-14-2013 at 04:39 PM.
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      07-26-2013, 05:03 PM   #2
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I'm glad your install went well! Can't wait to see the dyno sheet. Congratulations on making the beast even more beastly.
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      07-26-2013, 05:26 PM   #3
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Looking good. Too bad this beast isn't staying in Central Florida.

I agree PSI is a bunch of great guys. I don't trust anybody else in town with my car. They're truly passionate about what they do too - even in talking to me about options for header and section one on my paltry stock car. No project to small or too large.
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      07-26-2013, 06:14 PM   #4
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Those ASA blowers do give incredible midrange boost.

Even if the top end power is not there they still make for a really entertaining drive and quick point to point car!

Congrats and happy driving.
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      07-27-2013, 12:19 AM   #5
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nice review, glad the install went well. it's a real shame I never got my hands on the Gpower kit for mine before it ran out of production, oh well. I'll just live vicariously through your supercharged beauties.
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      07-27-2013, 08:30 AM   #6
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Ha-ha, can actually feel the vibes through my iPad! Sounds great, looking forward to more!
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      07-27-2013, 09:49 AM   #7
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how much RWTQ?
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      07-27-2013, 04:14 PM   #8
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Quote:
Originally Posted by beta View Post
I'm glad your install went well! Can't wait to see the dyno sheet. Congratulations on making the beast even more beastly.
Thanks! Looking forward to the dyno sheet as well.

Quote:
Originally Posted by GriffBrew View Post
Looking good. Too bad this beast isn't staying in Central Florida.

I agree PSI is a bunch of great guys. I don't trust anybody else in town with my car. They're truly passionate about what they do too - even in talking to me about options for header and section one on my paltry stock car. No project to small or too large.
Yup. I drove 11 hours each way to have them work on my car. I've got some big plans for the 3.0i too, but I've gotta wait for the mod budget to replenish first.

Quote:
Originally Posted by Sal@Evolve View Post
Those ASA blowers do give incredible midrange boost.

Even if the top end power is not there they still make for a really entertaining drive and quick point to point car!

Congrats and happy driving.
I appreciate it! Hopefully we'll see an FI option from you guys soon . The rumor mill is swirling....

Quote:
Originally Posted by 3point0 View Post
nice review, glad the install went well. it's a real shame I never got my hands on the Gpower kit for mine before it ran out of production, oh well. I'll just live vicariously through your supercharged beauties.
I didn't realize they stopped production for the non-M. It's definitely the highest quality option available. I wish I had gone that route on my 3.0i.

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Originally Posted by tbalutis View Post
Ha-ha, can actually feel the vibes through my iPad! Sounds great, looking forward to more!
Haha, nice! It's pretty bassy in person.

Quote:
Originally Posted by ZStig View Post
how much RWTQ?
Don't know yet... I only had a verbal from the shop about the rwhp. Once I get the graph I'll get all the data posted.
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      07-27-2013, 05:20 PM   #9
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pics pics picsssssss!!!!
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      07-27-2013, 06:02 PM   #10
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The car is DIRTY . The first pic is a little older. The ones with the hood open are after a 700 mile drive in the rain. It's raining again today, so once it stops for a bit I'll wash it up and take some better ones. The last one was taken by PSI at their shop.
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      07-27-2013, 07:19 PM   #11
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It's a nicely crafted set. Especially the manifold looks beautifully made.
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      07-27-2013, 08:08 PM   #12
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Looks great! Glad you are happy with it!! Do you track your car? I'd love to hear how she deals with heat.
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      07-27-2013, 09:26 PM   #13
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Quote:
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It's a nicely crafted set. Especially the manifold looks beautifully made.
It is. Looks even better in person. It's obvious each part was very thought out. The way the whole kit works together with the car feels more like an OEM naturally aspirated Z4M than a tuner car.

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Looks great! Glad you are happy with it!! Do you track your car? I'd love to hear how she deals with heat.
I don't track it at the moment. I plan to in the future. I'm guessing the stock brakes would give up well before the heat got to the engine.
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      07-28-2013, 07:17 PM   #14
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Installed my boost gauge today. Looks like I hit 6 psi just over 5k rpm:

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      07-28-2013, 07:32 PM   #15
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I saw 7psi. But being digital it jumps so it's a bit hard to get a 'feel' for the boost gradient. The flickering from the cam missync also doesn't help

This was 2nd gear? Cant you do a pull 4th to the revlimiter (when nobody's looking )

we need more vids ..... of everything!

what kind of mirror gauge is that?

I'm also still looking for 'the perfect meter/gauge' but I want it maybe in my ashtray. I'd love to get an all analog psi gauge (so a boost line to the interior), but that would need a really small dial and there would be no room for afr etc.
But somehow I think that an analog meter is much more responsive and gives a better feel for how the gradient/boost buildup is pictured.

You know, something like this:





Or this one is epic: instant boost at any rev to 8+psi!


(its in bar, so 0,5 bar is 7psi)
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Last edited by GuidoK; 07-28-2013 at 07:48 PM.
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      07-28-2013, 09:16 PM   #16
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Quote:
Originally Posted by GuidoK View Post
I saw 7psi. But being digital it jumps so it's a bit hard to get a 'feel' for the boost gradient. The flickering from the cam missync also doesn't help

This was 2nd gear? Cant you do a pull 4th to the revlimiter (when nobody's looking )

we need more vids ..... of everything!

what kind of mirror gauge is that?

I'm also still looking for 'the perfect meter/gauge' but I want it maybe in my ashtray. I'd love to get an all analog psi gauge (so a boost line to the interior), but that would need a really small dial and there would be no room for afr etc.
But somehow I think that an analog meter is much more responsive and gives a better feel for how the gradient/boost buildup is pictured.

You know, something like this:





Or this one is epic: instant boost at any rev to 8+psi!


(its in bar, so 0,5 bar is 7psi)
Haha, it's funny I've seen both of those when browsing youtube

I think the ash tray pods are discontinued by both 3D Design and LeatherZ. I have one I'm trying to get installed in my non-M, but I think I need to take the whole center trim out to get it to fit in. Beyond that, only certain gauges fit without modification.

I too prefer analog gauges, a byproduct of my aviation time. With a digital gauge, you have to process the number you're seeing, and then compare it with your brain's database of what's good and what's not good. When you're tired, amped up, or not thinking clearly for whatever reason, the disconnect may cause you to miss something. It takes an extra second to process. With an analog gauge, you simply glance at its position to know if you're operating normally. The video doesn't show it, but there is a position indicator on the AEM gauges. It's not as good as a swinging needle, but better than the number only.

http://www.radar-mirror.com/AEM.html

It's $500 for the incorporation of gauges, plus the price of the gauges. I ended up buying a spare mirror to have the gauges put in, so that the car wouldn't be down without a mirror, and I could return to OEM if I chose to. If I had to do it again, i would just send out my OE mirror and deal with not having it for a week or two. I won't return to stock.

For power, I would highly recommend getting a fuse tap (Link, thanks Rated M). Tap into Fuse #2, as it's empty and powers only when the key is in position 1 or 2. I still need to figure out the dimmer. I've heard of people using the M shift knob wires, but my knob has been dead for a couple years. I used a voltmeter and confirmed it's the wires that are dead. My ash tray light is also dead, which leads me to believe I have a fuse that's out. I haven't had a chance to track down which one.

So to summarize:

1. The gauge pod requires modification to gauges (addition of bolts to the back), or you must buy Stack gauges. I would just buy the Stack units. You must remove your interior trim to install the pod. You will lose the ash tray and power outlet, unless you relocate it. You have to look down to see your gauges.

2. The mirror gauges may or may not be distracting, and you will be without your mirror for about two weeks (or more for an overseas order). You are limited to two gauges, and your choices of gauges are limited. The price is the highest of any of the other options ($500 plus gauges, as compared to $375 for the pod or $400+ for the vent gauge). I haven't been able to get the mirror base cover back on, since I now have more wires protruding than can fit out the hole. I'll likely enlarge the hole when I get some time. The A Pillar, sun visors, and plastic trim between the A pillars must be removed to install. Running the wiring takes some patience. I bent up a coat hangar and taped the wires to it in order to feed it through to the fuse box.

3. The vent gauge is supposedly buggy, and according to reviews, there are a few kinks that need to be worked out. It can only display one reading at a time. You lose part of your driver's side vent. Otherwise, it sounds like a decent option.
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      07-31-2013, 12:43 AM   #17
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Great choice man.. how is the G-Power feel? do u like it? and you have got a nice rwhp numbers. did you face any issues or running smooth?
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      07-31-2013, 08:46 PM   #18
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No issues thus far. It really does feel like it's still NA, except with a lot more power.
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      08-08-2013, 01:47 PM   #19
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It was great to work with you on this project, I look forward to future plans on the other one.
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      08-08-2013, 03:06 PM   #20
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Where's the dyno sheet! Very curious what the torque curve looks like compared to the other kits on here.
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      08-14-2013, 04:40 PM   #21
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Updated with a dyno!
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      08-14-2013, 04:50 PM   #22
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Can you set the bottom of the graph to rpm? Also, what's the big dip in power?
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