Whatever happened to twin superchargers?
 

Hi everyone –

I’m considering a 370Z Nismo purchase, but only if it can be upgraded to my preferred stage of performance. I wish Nissan offered a bit beefier platform to work with! (For example, it’s possible to get 458RWHP from a non-aspirated 3.6l Porsche GT3.) I owned a turbocharged car many years ago, a 1988 Mitsubishi Starion ESI-R (running 14.5psi), and while I know turbo kits have made significant improvements since then in terms of reliability, I don’t want to own another turbocharged vehicle. The car was fun to drive, to be sure, but it was a money pit, too, despite the high-quality competition parts I had installed. I didn’t like the lag, and the non-linear powerband as well.

I was intrigued by the possibilities offered by a twin supercharger on the Z, but after using the Search feature on this board extensively, I discovered that there are no new threads for this kit…the most recent seems to be from about three or four years ago. There is only one TSC build listed in the sticky, although I thoroughly enjoyed reading his excellent writeup: http://www.the370z.com/members-370z-...a-project.html (I can only imagine how sad it was to sell this car after all that work!) I also went down the list of sponsors of this board to see who might be selling and/or installing twin units, but all I could find were one or two doing the Stillen single. Based upon what I’ve read, I won’t consider the Stillen. The quality of some of the parts is questionable, and the maps seem to be poorly-coded. I read the thread detailing the air-to-air conversion…holy cow…I don’t have the tools/experience necessary, and I know there are no shops nearby who could do this if I went this route. I also found the threads discussing the GTM/Gamma debacle. That’s certainly enough to give me pause about even taking a gamble on ordering parts!

If I do a Google search, I also come up with Vivid Racing and Horsepower Freaks selling what looks like the same twin-unit GTM (Modern Auto Performance?) offers. However, they don’t specify that it will work/fit with newer Z models (I’m assuming the newer models require different mapping). Are the units available for purchase now, unsold leftovers from the tooling several years ago, and just passed around from seller to seller via wholesaling? And where are the pro shops familiar with installation?

Are most enthusiasts just installing the TT kits for the most bang-for-the-buck and possible future upgrades, and not messing with the TSC kits because they don’t have the same potential? Or is there something else I’m missing? If I'm understanding correctly, it seems that SS Firehawk was able to see something on the order of 50-75 more horsepower at an equivalent psi over a single SC. I don’t race, drop the clutch, or otherwise pound a car, and am just looking for 450-475 RWHP with the stock exhaust on pump gas. (Not a fan of loud exhaust, or noisy blow-off valves, for that matter.) If I can reach my horsepower goal with 7-8psi instead of 10-12 from a single unit, then I would say it’s worth the extra money.

Thanks!

I'm still a big fan of supercharged Z's. The constant squealing, pulley, and belt alignment issues just left me jaded. Honestly, if you're serious about supercharging, Gamma seems to be doing better at delivering kits than GTM ever was. I would pay with a CC and be ready to cancel if they're late though.

There are some recent trends that could benefit supercharged Z's now. Billet oil pump gears and the ATI damper can allow you to max the supercharger by spinning the motor higher without grenading the pump. The ported TB's, ported uppers, and ported lowers will improve efficiency, ECUTEK is huge for tuning, especially with FI'd cars. We can actually tune to prevent blow through from too much valve overlap. Running Z1's shorties (they actually fit with the stage 2) would improve performance as well. There have been a couple GTM stage 2 kits come up around 550whp, I can't remember off hand. But now with E85 too, I think a properly built SC'd car can provide NA linearity, with turbo power (probably not more than 600whp though). I was just chatting with Elmo370Z about ho awesome it'd be to see how a high revving SC'd Z would perform.

Don't let your experience with older turbocharged cars turn you away from the concept. Things have changed a lot since the '80s. A Z with a properly sized turbo has almost no lag. Other than the initial spool-up, the powerband looks very similar to the NA powerband, only with 200+whp more.

It doesn't matter what kind of aftermarket forced induction you choose from a reliability standpoint. A turbo setup isn't inherently less reliable than a SC setup. It's all in part selection, maintenance and the tune.

Honestly, before you drop a LOT of money for the car and mods, see if there's someone local to you with a FI Z. A ride in both would make it a lot easier to decide. Post in the appropriate regional subforum here and see if someone will take you for a spin.

You are taking 28 year old technology and an inline 4 cylinder car and comparing it to todays tech and a 3.7 liter v6. Yes, i have rode in 4cylinder turbo cars and yes they are rediculously laggy, especially when the turbo is oversized to make some sort of decent high end power. These 370Z's with appropriately sized turbos have very negligible lag and that large displacement gets that turbo spooling up quick. You really need to go for a ride in one.

Also, I'm not trying to push you into the stillen setup with my A2A kit but had to chime in on the statement that you dont have a shop that could install it. If thats the case then dont buy ANY turbo kit either since they are way more complicated to install. 80% of the guys buying the upgrade are doing it in their garages. So if you dont have faith in a shop that does that for a living then i wouldn't take my car to them for anything at all.

The twin SC kit (if you can get one and Gamma doesn't GTM you in the ***) would be a hell of a lot more involved than a Stillen kit with the A2A setup or a BP single turbo kit.

If you want DIY boost, I second BP's kit. Cost efficiency, yes, it's the most economical of the turbo's, but one of the best available. Saving on labor is a bonus. Especially for the power you want, it would spool up quickly. I don't have to mention Fast Intentions kit, it speaks for its self as to the power those things make. I agree with Chuck and Topgunz tho. My "like" button is broken

With all the improvements over the years there is little reason to do twin anything besides show and extremely high power levels. A well designed single SC or Turbo can put out the results any twin kit can for reasonable power levels as both the BP kit and the A2A setups have proven.

Gamma has the twin SC kit for sale on the website... just FYI. It isn't cheap though!

Also, there are guys with a lot of miles running 600+whp on stock blocks on E85. That's plenty beefy.

Thanks everyone for your helpful responses and experience! My thought was, if I went this route, to have a car fitted/tuned in Atlanta (5-6 hours from here). But having owned a car with a complex tune before, I understand the need to have a trusted shop locally for "issues." Based upon what you all are saying, perhaps the inherent liability gotchas would prohibit a sane person from taking this on in a location like mine.

One of the things I thought I understood about the TT cars was the difficulty in doing routine maintenance. Everything is up top with SC engines, and while tight, doable without dropping the tranny or engine-out? Did I get this right? The photos of everyone's engine bays blows me away! There's hardly room in there to squeeze a hand or wrench!

I can just picture a local mechanic with a car like this on a lift, with a beer in one hand and scratching his head. "Ya said the oil filter was where?" :eek:

When I had my Starion, I used a bleeder valve instead of a wastegate, primarily because I didn't want the pssshhh. Delicate and risky, to be sure, but it worked out OK. A wastegate on a TT would be a dealbreaker for me, and I know I wouldn't want to trust a bleeder valve on an exponentially more complicated and expensive engine/build. Anyone else use bleeder valves any longer? I think I read in one of the threads about an internal dump for a blow-off valve...perhaps an advantage for a quieter setup on a SC?

Is there an advantage, though, to engine response by having a twin unit instead of a single?

No argument there...but aspirated vs. non-aspirated. I would prefer NA, but the Nissan platform doesn't really offer the same potential as Porsche, for example.

Great idea to try to find someone locally -- I'll give that a whirl!

You can have a BOV plumbed back into the intake. That's not a huge issue. A SC kit is going to have a BOV open until you put your foot in it. It's not particularly quiet. No matter what kit you buy, access is a pain in the ***. There's just not a lot of room. I'm confused about the issue with the wastegates. If it's plumbed back into the exhaust, there's no additional noise. You can't have a turbo without a wastegate. There would be no way to keep from overboosting.

I substituted a bleeder valve for a wastegate, to eliminate the noise. It was continually dumping a tiny amount of pressure, to be sure, but wouldn't allow the pressure to go any higher than what I had it set for.

I didn't know about plumbing a wastegate into the exhaust...no one thought of that in the '80's! That might be an acceptable compromise.

I think you are confused about the difference between a wastegate and a blow off valve. A bov will make the pshhh sound and release pressure in the charge system. Wastegates bleed off exhaust gas only and an open dump wastegate doesnt make a Pshhh noise.. It goes. BBBBBRRRRRRAAAAAPPPPPPPPP!!!!!!!! and will blow your ears out and anyone beside you. But, it does sound beast mode.

I rode in another fellow's Starion years ago (and was running a lot more boost than me), who had a wastegate, and it made that psshhh sound every time it opened/dumped. But maybe you're right...perhaps I'm getting terms confused, possibly because the tuners I communicated with at the time used the wrong terms too.

The sound you described would drive me crazy!

I think your confused about what car you want.

You want over 400whp N/A. You should look into a new mustang 5.0 or a camero.