Supercharger tech info

[rx7tt95]

I apologize if it's been hashed out and answered a hundred times over...did a search and didn't find any cohesive answers to my particular questions. I guess Tone would be the logical person to ask. I've been "away" from the VX boards for some time and am just returning. When I left, the SC kit was just getting started...so here it goes!

1)What's the expected hp output for the SC-related parts alone, ie. no exhaust/intake?

2)What boost level is this SC producing?

3)Does it have a bypass or electromagnetic clutch for cruising situations?

4)How is fuel handled, specifically, is it simply a rising rate FPR or FMU (fuel pressure regulator/fuel management unit) or is it handled via ECU reprogramming (MAP sensor?) with stock or larger injectors?

5)Is the warranty void if mufflers and intake are added after the installation?

6)What model SC is being used, what's the maximum boost recommended by the SC manufacturer, and if possible any thermal efficiency numbers? I remember reading that 3.5L was the upper limit for an SC kit listed on the BBS. Wasn't sure if it was for the Alpine kit or another being produced.

7)I'm no expert on automatic transmissions...I noticed that a "beefier" torque converter is offered. Is this all that is needed to enable the transmission to handle the additional hp/torque the SC along with other performance goodies (intake/exhaust, etc..) I understand the stock transmission will be fine with just the SC and no other modifications.

8)What's the expected MPG drop with the addition of the SC assuming you NEVER get into boost. Are we looking at 1mpg parasitic loss?

I know Tone could probably answer ALL this stuff and more but I thought it would be helpful if it was posted for all to read. That way he would only have to answer it once.

[Tone]

Good questions - let me know if you need more info.

1)What's the expected hp output for the SC-related parts alone, ie. no exhaust/intake?

40+ Rear Wheel Horsepower and at least an equal amount of torque - see chart and info on my page - I have seen up to 75 RWHP on some dyno runs on an Amigo


2)What boost level is this SC producing?

4-5PSI

3)Does it have a bypass or electromagnetic clutch for cruising situations?

Sophisticated vacuum bypass - unnoticeable transition!


4)How is fuel handled, specifically, is it simply a rising rate FPR or FMU (fuel pressure regulator/fuel management unit) or is it handled via ECU reprogramming (MAP sensor?) with stock or larger injectors?

Stock ECU is able to handle and adjust for the added air - even at the 5 PSI I am running, I am still running rich. Stock injectors can handle more boost when we use a UniChip to allow longer pulses.


5)Is the warranty void if mufflers and intake are added after the installation?

No - recommended.


6)What model SC is being used, what's the maximum boost recommended by the SC manufacturer, and if possible any thermal efficiency numbers? I remember reading that 3.5L was the upper limit for an SC kit listed on the BBS. Wasn't sure if it was for the Alpine kit or another being produced.

EATON M62, 3rd Generation Roots style - see Eaton or Magnuson (Eaton’s aftermarket division) web site.


7)I'm no expert on automatic transmissions...I noticed that a "beefier" torque converter is offered. Is this all that is needed to enable the transmission to handle the additional hp/torque the SC along with other performance goodies (intake/exhaust, etc..) I understand the stock transmission will be fine with just the SC and no other modifications.

Better torque converter would be recommended if you drive it hard all the time - otherwise, we are within spec for the powertrain. This kit was designed with input from Isuzu as they contacted Alpine about it as well as TRD engineers. I do recommend the use of the AutoTrans Interceptor electronic shift kit on any VX that is driven spiritedly.

8)What's the expected MPG drop with the addition of the SC assuming you NEVER get into boost. Are we looking at 1mpg parasitic loss?

Technically tiny if you never hit boost and there is the potential to increase it slightly as the engine does not have to work as hard. Parasitic drag is less than 1hp around town. I only notice increased fuel usage when driving it hard.

[Moncha]

Yeah! What he said! ;pg;

[IsuZOOM]

Originally posted by rx7tt95
8)What's the expected MPG drop with the addition of the SC assuming you NEVER get into boost.

I've always heard that with superchargers, at normal day-to-day street driving your MPG will increase if you drive the same as you did before the SC. The engine does less to acheive the same speeds, so you use less fuel. Of course, in reality, you end up driving it harder and faster... ;eekg;

[TDAWG]

I have 2 tip my hat off to rx7tt95 for aasking Tone some interesting questions. Since I joined the club and read about almost all of the supercharger questions this is the 1 time that someone asked some real questions. I can't beleive that it seem to have stump Moncha 2 LOL.

[vx69]

I am not sure about for every one but I have expierienced some increase in mpg. I used to get 17 on day to day driving but now I am getting about 19. If I try to keep my foot off the floor I have seen as good as 21!!!!!

[chumone]

Anybody know any installers in the LA area that could install the kit for me? I'm rather inept with anything mechanical.

[Moncha]

Originally posted by TDAWG
I can't beleive that it seem to have stump Moncha 2 LOL.

Who said I was stumped... I just couldn't add any more!

[rx7tt95]

Excellent info Tone. I greatly appreciate it. I forgot that we're using a MAS to measure airflow...I'm used to speed density systems, no restrictions, better for hp, but you need to be a really good tuner to get things right. I'm surprised the ECU has enough cell "range" to cover 5psi. It's very good news though.

What is limiting us to 5psi? Is it the cast pistons/rods?

On the rich fuel settings, forget a Unichip. I have a local here in town that tunes Porsche's this way...seems way too expensive to me although you can modify timing. One electronic unit you may wish to try out is the Apexi S-AFC which is a $350 "box" with LED display that allows you to +/- air fuel by 30% in either direction. One would need to acquire a PIN out map for the stock ECU and as it's universal, it'll cover any car out there. You'll also have to know if TPS voltage rises or falls with throttle application. I used it and a LINK system (Flyin' Miata uses the LINK out of Australia) and had better drivability, ease of use with the S-AFC. Might be worth your while to try out.

There's also something called the Do It Yourself wideband which uses a Bosh and NTK UEGO sensor (wideband) to measure a/f ratios. Place a bung in your exhaust BEFORE the catalytic converter and you can monitor accurate a/f ratios. Cost is about $350 for the sensor and DIY "box".

I'm at work currently but I'll get links for everyone when I get home later tonight.

Thanks again for the info!

[Hotsauce]

the SAFC is very popular with many other import cars. I have one on my Mitsubishi. Actually it will go + or - 50% fuel, and has a WOT, and a prt throttle fuel map.

The SAFC works by intercepting and modifying the signal from the air meter. this will fool the ECU into adding more or less fuel.

Do understand if you mess with anything with this much adjustment range that you have taken the responsability for the fuel mixture into your own hands, and the price of mistake is steep.

I wouldn't tune from just o2 readings, I like to have an EGT, and datalogger running.


John C.

[Moncha]

Now I feeling REALLY old! I remember tuning just meant a good ear and a timing light..

[rx7tt95]

I definitely don't disagree with you Hotsauce, whenever I have the RX7 in for a bit of tuning, all three items are in use. But if Tone's seeing a/f ratios say in the 10's (random number), there's really no harm in leaning it out to say high 11's or low 12's at 5psi. Remember it's an SC and not a turbocharger and EGT's, unless timing is waaaaay off, won't be as hot at a turbocharged car. A really good, fast acting wideband with datalogit would work pretty well for most.

They must have changed the SAFC since I purchased it as my unit is only +/-30%. I know the new HKS unit is +/-50% but I do not know much about it otherwise.

As for the wideband link...
http://www.techedge.com.au/
Delivery took less than two weeks. You can order them pre-built or if your a sadist, you can build them yourself and save a few bucks. I use version 1.0 along with an Apexi Power FC and something called FC Datalogit (essentially turns the Power FC into something just short of a Motec). There were initial teething problems as there's no linear voltage output from the wideband and thus required a polynomial equation to create an accurate voltage to a/f ratio correlation. Wasn't super difficult, but not plug and play with my datalogit system. There was also no temp control on version 1.0 which I believe has changed with 1.5 and 2.0. They do offer a display and I believe there are third party Palm logging programs out there.

I tune by average which means each cell must have LOTS of data (which I can log). I need about 50 data points per load/rpm cell to really tune accurately. Along with EGT too. Occasionally I have access to a 5 gas analyzer on a Clayton dyno (only two in the world right now) which can really help you pinpoint if it's a fuel or ignition solution. But with the PFC, Datalogit, EGT (non logged, peak hold) and DIY wideband, I've tuned a car that's capable of 10's and daily driveable to boot.

Anyway...they're pretty powerful tuning tools, especially for the money. Not for the newbie however and I do recommend that if you have no experience, you leave the tuning to the experts. But if you do have a bit of experience and are looking to push the VX to the edge, these tools will help. Maybe Tone will be able to grab that elusive 13 second 1/4 mile time with a bit of tuning :-)