G-Power SK I versus ESS VT2-500

[pokeybritches]

G-Power SK I versus ESS VT2-500

11/21/2014
I've had a few requests to compare the two supercharged Z4Ms. At this time the cars are not co-located; the ESS car is still fairly new to me; and they have other differences beyond the supercharger systems (mainly with regards to mileage and exhaust setup). I think the best way to do this is to keep a logbook format and update as new information becomes available.

Sights
G-Power
With the hood popped, the G-Power kit pretty much takes over and defines the car. It's not subtle. Orange is polarizing, but I love it and it's grown on me. I would prefer the intake manifold be painted imola red to match my interior, but I guess orange in the engine bay is a retro hotrod thing. I can always have it repainted, but it's doubtful I will ever do it. The orange would look best on a white or black car, though I can see it standing out well with blue. If you have a red car, expect to spend some money painting it. I've seen a lot of shocked faces when popping the hood. Non-enthusiasts know it's been heavily modified, even if they don't know quite what they are looking at (dude, thats a badass turbo!!). If showing off your engine bay is your thing, go with G-Power hands down.


The larger radiator can be seen from behind the grills, but I've only had one person comment on the intercooler (technically aftercooler). Most people, including enthusiasts, won't know the car is supercharged. The larger radiator will leave about half of them guessing, assuming they notice it in the first place.


ESS
The ESS engine bay is more stock-looking. I've had non-BMW car enthusiasts ask me if it was stock. Anyone who knows BMWs will immediately know what it is. Because it's black, it will match any car, although it won't stand out. That's not to say it's unimpressive. "Reserved" would describe it. While it's a small thing, I love the font they chose for "ESS Tuning". Nothing in the engine bay looks bad or out of place. It's a very clean kit that's not as showy as the G-Power.


With the hood closed, there is no hiding that the car has forced induction. The intercooler is clearly visible, which is a good thing. It's not flashy. It gives the appearance of a car that's well-sorted and content with what it is - no more, no less. I'm supercharged, yes, and I'm neither hiding it nor showing it off. It doesn't look out of place. In this aspect, I prefer the ESS kits intercooler.


Sounds
G-Power
The G-Power bypass valve sounds like a blow off valve, but it's not as loud as actually venting to the atmosphere. This has to do with intake setup (I have a Tial BPV on my non-M, and it can't be heard from the driver's seat). My G-Power Z4M has Supersprint V1 stepped headers, Supersprint section 1 with HJS cats, stock X-pipe, and Rogue Diablo mufflers. In other words, it's loud. I can't hear the ASA supercharger at all. Sound-wise, the only thing I can hear that tells me the car is supercharged is the bypass valve's PSHHHHH sound in between shifts. I don't know how much of it is due to the exhaust being as loud as it is, but I can say for certain that it's quieter than the ESS's Vortech unit. One of my only gripes with the kit is the intake has a bit of a rattle at idle. There may be something I could do about this, but nothing is readily apparent. I haven't spent much time tracking down the issue either.

ESS
ESS's Vortech sounds vastly different from the ASA blower. This is my second car with a Vortech, and both make similar noises - a little bit of whine that changes in pitch with rpm, and the hisssSSSSS!!! of boost building. Where I can't hear the ASA blower, the Vortech is audible but not overly loud. The only exhaust modification done on the ESS car is Supersprint Race Mufflers, and those compliment the supercharger's sound pretty well.

The bypass valve sounds different on the ESS car too. I will likely swap it out for a blow off valve that vents to the atmosphere, depending on how hard it is to replace. I still haven't figured out why its sometimes more pronounced and other times silent. It sounds good, but it's too quiet for me. It makes a sound similar to what I've heard on heavily modified turbo cars, almost like a low frequency squeak. It doesn't have the PSSSHHHH sound of the G-Power's bypass.


Feel
G-Power
"This car wants to rip my face off." - my first passenger.
"...." - my second passenger, with a death grip on the door handle.

You get the idea. Power comes on immediately and hard. A novice would kill himself in 5 minutes with this car and no DSC. That's not to say it's unpredictable... just the opposite actually. It does exactly what you tell it to do. If you put your foot down, it brushes off traction control's attempts at intervention, laughs, and continues to overpower the tires. The difference in power between this car and a stock M is greater than the difference between a stock M and a 2.5i. A flashing triangle has become a standard part of 2nd gear. I don't floor it in 3rd gear while changing direction, because it regularly spins the tires in that gear too. Everyone that has been in both cars comments on how aggressive the G-Power Z4M is in comparison. The ESS Z4M is absolutely eager, but it doesn't leave passengers with eyes like dinner plates, mainly because of the power's immediacy in delivery and quantity delivered. FYI, it makes a lot more than the rated 450 bhp and 5.8 psi of boost. I see 7 psi from 5500+ rpm in the summer, and 8 psi in the winter.

I have a bigger traction issue in the G-Power car. I expect it would pull hardest against my ESS car from 4krpm - 6krpm. It requires more concentration to drive quickly. With the ESS car, I can floor it at low rpm with minimal risk of spinning, and then as power progressively builds and I possibly lose traction in the upper rpm, I can shift to a new gear and start the process over from the S54's midrange revs. Easy. With the G-Power car, I have to back off and feather the throttle, because shifting gears would put me at revs too low to generate any boost. I have to stay with it and yield without being abrupt. It requires a better driver so as not to kill yourself, but if you're competent, it's not hard to control.

I expected more up top, mainly because there is so much down low. The G-Power car runs out of steam above 7k rpm, which is probably why its peak numbers are deceptively low. The best way I can describe it is it feels like the car has had a large V8 or V10 swapped in, and the last 1000 rpm is overrun.


ESS
I expect that the ESS Z4M will put out better peak numbers once I get stepped headers installed. It's deceptively fast, because power builds so progressively. It's smooth and delivery is linear. It doesn't shock like the G-Power Z4M. It requires more intent in order to get in trouble. The car feels like it could happily rev to 9-10k rpm. I find myself enjoying the upper end of the power band more in the ESS car than G-Power car. I do like that I can plant my foot at low rpm without fear of overwhelming the rear tires, and how easy the car is to control.

I really don't know which car will end up being faster. After some exhaust mods, I bet the ESS car will put down more power in the upper rpm, and could probably win a drag race from a dig. From a roll, my money is on G-Power, assuming good traction. Right now, with the ESS car's stock U.S. headers, and the G-Power car behaving like I've lassoed a Tyrannosaurus, the G-Power Z4M would put bus lengths on the ESS Z4M. Again, it's not yet a fair fight, and I'm anxious to see what the ESS car can do with some good stepped headers. More to follow.

11/28/2014
Sound comparison:

[Beedub]

great to see some actual real world experience on this, you've been so quiet about the g-power since it was installed, infact all the g-power owners have...

some things of note, that g-power blower is SMALL.... with its CFM rating past 6900 its running out of its efficiency range, so low down you get that turbo like TQ but high up it looses out and feels like a small turbo running out of puff, and the biggy, with the current hardware supplied their is NO upgrade path, you need new coolers, bigger s/c and why the kit isn't supplied with an oil cooler is beyond me, i can heat up mine pretty quickly and i have the larger setrab unit. If used properly on a track your car would become a hot mess very quickly anyone thats got FI and has done so can tell you an oil cooler is a must on an Fi s54. My biggest gripe with the g-power is that its changing the character of the s54 too much, i don't want it run of power at 7k... i still have another 1k revs i WANT to ring it out.... They SHOULD have over specced on that blower, and its adequate for its job but theirs no scope for more..

The ess hardware is just where it wins imo, you can boost it up as much as your wallet will allow, the blower can take well over 600whp and not spew its guts out, the air 2 air is just win, the car feels like it will rev into the stratosphere, boost is ALWAYS building and never falling off, however i do agree its making it down as low as the ASA unit.

my ess car has extensive mods across the board, and this year it proved itself on track, we was first position pretty much all season against some serious cars, GT3s, tuned evo's, this was all achieved on road compound nankang semi slicks. It feels ballistic from far lower than you describe, traction is my biggest issue, even with semi slicks on.

ALL the kits available are pretty awesome in their own right, but for me.... the ess hardware wins hands down against the competitors, the time taken to actually fit in that A2A cooling setup works wonders.

ultimately, if mine was purely a road vehicle i think i would choose the g-power actually, perfect for a road car, but... if you want to actually track the thing and hard and be reliable doing so, the ESS kit is where its at, its proved itself to me with countless all day sessions in pulverising heat. The one i wouldn't touch personally is the VFE setup. i do not rate them people at all.

Pokey thanks for posting this up, really enjoyed it, and i agree on the ESS noise, its kinda sucks, all you hear is that kinda muffled turbo noise, a building hiss and that low down compressor whistle noise, not the best noise at all. I'm still re-circing as i want every bit of air back into the plumbing as possible !!

[GuidoK]

On the G-power, where's your steering fluid reservoir? Is that that little cannister behind the orange intake?

As for looks: you should try to modify that silicone hose that runs over the g-power manifold (it sticks out), maybe reroute it so that it goes around the back. What is that hose? CCV? Fuel return/tank vent?

Big difference also seems to be the pulley size. Does the g-power have a clutch in that pulley (I know they had that in the past)?
To cut off during idle I think.
And I think the g-power set has an air2water2air heat exchanger setup I think? (just like the new m3/m4)

[Beedub]

Originally Posted by GuidoK

On the G-power, where's your steering fluid reservoir? Is that that little cannister behind the orange intake?

As for looks: you should try to modify that silicone hose that runs over the g-power manifold (it sticks out), maybe reroute it so that it goes around the back. What is that hose? CCV? Fuel return/tank vent?

Big difference also seems to be the pulley size. Does the g-power have a clutch in that pulley (I know they had that in the past)?
To cut off during idle I think.
And I think the g-power set has an air2water2air heat exchanger setup I think? (just like the new m3/m4)

yes i have seen the m3/m4 setup in detail and its pretty fucking nice... it has some serious capacity with the numerous radiators tucked all over the place, one of them is mounted flat parallel with the floor in the nose of the bumper, VERY cool.

[Beedub]

can't lie as well, OP I'm very envious of your 2 blown z4s.... what a position to be in :-)

[pokeybritches]

Originally Posted by Beedub

can't lie as well, OP I'm very envious of your 2 blown z4s.... what a position to be in :-)

Thanks! I'm stuck at work waiting on a contractor to finish up some things, so I wrote a pretty extensive response... then the power went out lol. I'll post it when I get home.

Keep in mind my G-Power car has very high miles, so it needs some TLC. I counted 35 things it needs cosmetically lol. Bringing it back to like-new condition is my winter project.

[pokeybritches]

Originally Posted by GuidoK

On the G-power, where's your steering fluid reservoir? Is that that little cannister behind the orange intake?

As for looks: you should try to modify that silicone hose that runs over the g-power manifold (it sticks out), maybe reroute it so that it goes around the back. What is that hose? CCV? Fuel return/tank vent?

Big difference also seems to be the pulley size. Does the g-power have a clutch in that pulley (I know they had that in the past)?
To cut off during idle I think.
And I think the g-power set has an air2water2air heat exchanger setup I think? (just like the new m3/m4)

The power steering fluid reservoir is buried underneath the first part of the intake manifold that the air filter is clamped to. It's not hard to access, but it requires a bit of disassembly. The piece you were asking about is actually the bypass valve.

You're right in that moving the black hose would make it look better. It's part of the CCV.

I'm not familiar with what the new M3/M4 uses, but I'll check it out. I haven't run this car hard on a track like Beedub, but I've had no heat issues in spirited summer driving. It's about time to check the reservoir levels, so I'll poke around a bit and see what I can find. I kinda wish I would have installed this myself so that I would know where everything is and what it does.

[GuidoK]

I meant that the g-power setup uses an air to water heat exchanger to cool the inlet air and a water to air radiator to loose the heat.
That is different to the ESS setup that uses a normal intercooler.

Are both cars alpha-n or map tuned?
I know that a lot of G-power setups over here have problems with (amongst other) the MAF wearing out frequently probably due to the open filter (you see where I live both the sk1 and the sportydrive sometimes pop up, but on M54 engines), but on the z4m the MAF is obviously missing. (on the m54 it sits just behind the filter where there is now the silicone coupling)

[tikamak]

The ess kit is not track ready and ess have some problems with getting the correct parts for your kit and lousy customer support. You can check gmd2003's threads and his accident due to his kit getting inadequate injectors the first time around

[ZStig]

very interesting comparison, thank you

[Beedub]

gmd did get loads of wrong parts and customer service can be sketchy unfortunately.... can't refute that, ess seem to have a knack at sending out numerous wrong parts, not good if you on the other side of the world and your cars awaiting parts from them.

my personal experience has been pretty good in all, they sent me a brand new blower OUT of warranty when my tuner fucked it up,

i would love to see a viable bolt-on turbo kit, but i don't think we will ever see that.

[tikamak]

The warranty is the vortech warranty not an ess one.
I cant say anything about my vt2-500 since it was a beta kit.

But gmd2003 is living in the US and not the other way around the world. You can check his threads about how far the ess parts are underspecced to handle the stresses of the track. That includes the oil cooler replacement they send out underspecced for the amount of power the kit is supposed to make.

The ess tune is good, although it could be done better. Basically theres little calibration on mid RPM and only good calibration on high RPM where it counts.
Expect to have black exhaust tips fairly quickly due to the tune running a tad richer than most other tunes. Thats normally a safety measure to keep your engine reliable but it could be done better if you ask me.

[Beedub]

GMD is was past normal track driving and competes that car on a near racing level. The car and kit is being tested beyond what anyone else has done on this platform imo.
For me.... on the grand scheme of things, I'm very happy with the kit and its performance, i would say 90% of ESS owners would probably say the same. We all have different experiences, thats life I'm afraid...

I've had my beefs with ESS but.... i simply can't refute the performance , reliability and even their customer service towards me, even if they have utterly pissed me off at times. also the upgrade kit prices are a piss take imo.

[pokeybritches]

Originally Posted by Beedub

great to see some actual real world experience on this, you've been so quiet about the g-power since it was installed, infact all the g-power owners have...

some things of note, that g-power blower is SMALL.... with its CFM rating past 6900 its running out of its efficiency range, so low down you get that turbo like TQ but high up it looses out and feels like a small turbo running out of puff, and the biggy, with the current hardware supplied their is NO upgrade path, you need new coolers, bigger s/c and why the kit isn't supplied with an oil cooler is beyond me, i can heat up mine pretty quickly and i have the larger setrab unit. If used properly on a track your car would become a hot mess very quickly anyone thats got FI and has done so can tell you an oil cooler is a must on an Fi s54. My biggest gripe with the g-power is that its changing the character of the s54 too much, i don't want it run of power at 7k... i still have another 1k revs i WANT to ring it out.... They SHOULD have over specced on that blower, and its good for its job but theirs no scope for more..

The ess hardware is just where it wins imo, you can boost it up as much as your wallet will allow, the blower can take well over 600whp and not spew its guts out, the air 2 air is just win, the car feels like it will rev into the stratosphere, boost is ALWAYS building and never falling off.

my ess car has extensive mods across the board, and this year it proved itself on track, we was first position pretty much all season against some serious cars, GT3s, tuned evo's, this was all achieved on road compound nankang semi slicks. It feels ballistic from far lower than you describe, traction is my biggest issue, even with semi slicks on.

ALL the kits available are pretty awesome in their own right, but for me.... the ess hardware wins hands down against the competitors, the time taken to actually fit in that A2A cooling setup works wonders.

ultimately, if mine was purely a road vehicle i think i would choose the g-power actually, perfect for a road car, but... if you want to actually track the thing and hard and be reliable doing so, the ESS kit is where its at, its proved itself to me with countless all day sessions in pulverising heat. The one i wouldn't touch personally is the VFE setup. i do not rate them people at all.

Pokey thanks for posting this up, really enjoyed it, and i agree on the ESS noise, its kinda sucks, all you hear is that kinda muffled turbo noise, a building hiss and that low down compressor whistle noise, not the best noise at all. I'm still re-circing as i want every bit of air back into the plumbing as possible !!

I think the reason I've been so quiet (and possibly the other owners as well) is that the G-Power kit works great, right out of the box, and I haven't run into any real issues. There's not a whole lot to talk about, and there aren't many owners out there. It does exactly what it's advertised to do, and more, and I'm sure you agree- anyone that's had aftermarket forced induction kits knows that it always looks better in the book than on the car, and there are always quirks. With this kit, there are none. Nothing to be disappointed in, no surprises other than the good low end torque. I’d expect that if one kept the ESS kit standard, it would be the same way.

The blower the G-Power uses is the ASA T1 518, which is supposed to develop up to 560 horsepower. Power isn’t a good way to rate a blower, because so many things can influence power. I’ll take some measurements to figure out what rpm it’s running.

http://www.precision-sport.com/shop-...e-and-roadster




http://asasc.com/superchargers/t1-518

You are dead on with the statement about it behaving like a small turbo (obviously without any lag). The blower isn't small size-wise (it looks to be the same size or larger than the Vortech). It’s happiest from 4-7k rpm, whereas the Vortech is a bit of overkill, which is why it feels content at high rpm. The G-Power car still makes good power at high rpm, it’s just already peaked and not ramping up like the ESS car. The character isn’t dramatically different from a stock S54 other than the extra power. A stock S54 levels off at 7k rpm too; the G-Power peaks at 7k and power falls off slightly but not drastically. The shape of the curve is similar to stock. I’d argue the Vortech is further from stock, but that’s not a bad thing. It’s got a different kind of character. I wouldn’t keep both cars if one was superior to the other. It may have just been a while since I’ve driven a stock Z4M, but the ESS car doesn’t feel OMG impressive in the low-midrange. It’s quick for sure, and probably a lot quicker than stock, but it doesn’t claw its way up the road in the same fashion at that rpm. What you give up in the midrange on the ESS car, you make up for with top end power.

As far as upgrades are concerned, you are correct. If you want a kit to tinker with, the G-Power kit is not the way to go. It’s good as-is, like the Ferrari of Z4M forced induction. Any attempts to modify it will toss away its best feature, which is how well-sorted it is, and it will be very expensive. It’s odd I know, but I honestly have zero desire to mess with it. In my free time I find myself looking for mods to my VF Engineering 3.0i (cams, etc.) rather than the G-Power kit. I think it’s something about the power delivery of the Vortech that makes you want that extra kick at the top end, even if you don’t really need it. With the Vortech, the car feels so happy being wrung out to redline.

The ESS kit has hardware barriers of its own, which is why I won’t screw with it while it’s running perfectly. The injectors are small and can cause limp issues if power is increased, the Vortech doesn’t have enough belt wrap and can slip with smaller pulleys so you’d need to change all the serpentine pulleys including the crank (the ASA blower has massive belt wrap), oil filter housings can crack (both Zstig and my car’s previous owner have had to replace theirs)… and then you run into standard Z4M hardware issues such as fuel system upgrades, differential not locking, traction due to tire width, clutch limitations, etc. All engine hardware upgrades require an alpha-n retune to function properly, since its adaptation potential has been compromised without a MAF sensor. It’s going to be expensive either way.

My car has an oil cooler (I believe it’s the OEM oil cooler). I’m not so sure it will become a hot mess before the brakes give out. They are the weakest link. Pending a brake upgrade, the radiator is HUGE and the car isn’t putting out insane power (only 7-8 psi max), but it’s all conjecture. The ESS kit sounds like it’s proven to be sustainable for extended sessions on the track, and although G-Power does race their own cars, no one has put a G-Power S54 FI kit on the track that I know of. For a few laps at a HPDE, I expect the G-Power would be fine. For a car that spends most of its life on a race track (and had better have dampers with external reservoirs, R-comps, brake upgrades, cage, seats, etc. to go with it), the ESS kit would be my choice. Besides the air to air cooling, I’d do it because its power delivery is linear and predictable, and you’re less likely to get in trouble with it.

I recommend you consider moving to a BOV setup for heat reasons, especially on a track car. All that unused air has been compressed and is hot, and I wouldn’t want it recirculated back into my intake to be compressed again. At WOT you aren’t losing any air with either setup. At part or no throttle I’d rather just dump the extra hot air than send it back through the system. I don’t know if it makes a huge difference, but it’s the way I will go. The sound is cool too… not ricey or gimmicky.

I’m glad to be of help where I can, and I welcome any opinions or advice. I think I prefer to drive around the ESS car right now just because it’s newer and cleaner. My G-Power car has 116k miles, a few dings and needs some minor cosmetic work. My ESS car is mint other than some small rock chips.

[Beedub]

pokey you are a cool dude my friend. Great attitude to pretty much everything.

don't forget we are dumping the air thats already in the intake plenum, this has been cooled already so it shouldn't be dumping hot air back into the system.

line these things up, video and become a zpost hero!!!

[Steeler]

Originally Posted by Beedub

pokey you are a cool dude my friend. Great attitude to pretty much everything.

don't forget we are dumping the air thats already in the intake plenum, this has been cooled already so it shouldn't be dumping hot air back into the system.

line these things up, video and become a zpost hero!!!

Pick me I volunteer to drive one of the M's

[pokeybritches]

Originally Posted by dbarton62

Pick me I volunteer to drive one of the M's

Come down south!

[Beedub]

pokey can you post the schematic drawings of the G-power intake manifold. Wondering how much of the intake manifold is cooling material for the air, the VF has a significant cooling cartridge that looks as large as the intake itself, is the g-power the same ??

i love the drawings they provide with this kit, they are seriously detailed and would not be cheap to have initially produce.

[pokeybritches]

I don't have any paperwork from the kit. I've requested it from G-Power.

[pokeybritches]

Sound comparison:

[pokeybritches]

P.S. NEVER EVER edit a long post with the Bimmerpost app!!!!!!

It messed up all of my pictures (trying to automatically add a url link instead of leaving them alone), and it deleted every single apostrophe, hyphen, quotation mark, and special character (like "...")

[pokeybritches]

We ran them tonight, side by side, from 3rd gear. I won't post the video publicly, but members with 50+ posts can PM me and I will send it.

First run - 4k rpm, 3rd gear. No contest. G-Power car won by 3 car lengths.

Second run - 3k rpm, 3rd gear. G-Power car was a split second late on the throttle, but pulled ahead by 1-2 car lengths by the top of 3rd.

Surprisingly, the G-Power car was only a little faster until 5k rpm, where it just took off.

I can't wait to get some stepped headers installed on the ESS car.