Which Supercharger?

[why1504]

I am doing some preliminary investigations into adding a Supercharger to an NSX. Can some of you give me some thoughts as to which one is the best value. I do not plan to go into the motor. I do plan to add an inter cooler, headers, and an exhaust system. Currently, I am considering the Computech unit and the SOS system. Are there other SC I should consider? I am willing to spend more for more performance. But I don't want to screw up reliability.

Which Header and exhaust should I be looking at?

How difficult is the installation? Can I do this myself? How long will it take?

Should I swap the clutch before I start?

Is there any other maintenance I need to perform during this upgrade?

 

[A.S. Motorsport]

I am doing some preliminary investigations into adding a Supercharger to an NSX. Can some of you give me some thoughts as to which one is the best value. I do not plan to go into the motor. I do plan to add an inter cooler, headers, and an exhaust system. Currently, I am considering the Computech unit and the SOS system. Are there other SC I should consider? I am willing to spend more for more performance. But I don't want to screw up reliability.

Which Header and exhaust should I be looking at?

How difficult is the installation? Can I do this myself? How long will it take?

Should I swap the clutch before I start?

Is there any other maintenance I need to perform during this upgrade?

All depends on your goals (how much power and tq)

Installation difficulty will depend on your skill level.
A SC install will take apx 11 hours for a CT-Engineering kit (comptech)

I'd recommend a CT Engineering supercharger they provide excellent quality and reliability.
It's probably the most common NSX Supercharger.

 

[TURBO2GO]

I am doing some preliminary investigations into adding a Supercharger to an NSX. Can some of you give me some thoughts as to which one is the best value. I do not plan to go into the motor. I do plan to add an inter cooler, headers, and an exhaust system. Currently, I am considering the Computech unit and the SOS system. Are there other SC I should consider? I am willing to spend more for more performance. But I don't want to screw up reliability.

Which Header and exhaust should I be looking at?

How difficult is the installation? Can I do this myself? How long will it take?

Should I swap the clutch before I start?

Is there any other maintenance I need to perform during this upgrade?

The SOS system makes more power, but you are getting into fuel management which adds some level of complexity. The CT system doesn't rely on aftermarket fuel management. IMO that makes it slightly more reliable but that doesn't mean the SOS system can't be reliable as well. You'll need to tune, and all the reliability depends on your tune and tuner's capability. There is no tuning with CT system. It is plug and play.

Also the intercooler requires a seperate heat exchanger, hoses, lines, etc. Again adding more complexity.

You don't need to upgrade the header if your car is NA2 (97+). There are a number of good exhausts at reasonable prices. From Taitec to Angus's unit to CT, all depends on what you are looking for.

The intercooler lowers intake temps, creating reliability for the motor and more power. But you are inching closer to the 400+ range and that will be starting to stress the internals of the motor more at WOT. Anything less than WOT is probably better.

As for the clutch... depends on how you drive the car a lot more than the fact that it is SC'ed. The factory clutch will not hold up to a SC'ed car driven hard. Mine is about to go, but that is because I have about 12 track days on the car. And I am rev matching, double clutching, and heel and toe'ing. You can use your factory clutch until its gone then just upgrade it. It may last you a while if you don't drive too hard.

One last thing... if I had to do it all over, I'd keep my car NA and concentrate more on driving schools and getting better with the car. I don't see the point of a SC unless you want to win drag races at stoplights, which is dumb anyway. This car has a lot of capability and other than the few people that are good trackers, most people that own NSX's have nowhere near the driving capability the car has. I did my upgrade because I was bored. You get bored, you want more power. The best relief from that boredom is to take your car and drop it into its home environment, the racetrack. You will quickly find out you are a long way away from needing more power. Once you get really good, you can upgrade the suspension, and if you are now so good that power is truly becoming a limiting factor, you SC or turbo the car. Until that point all more power will do is limit your learning capability. You want fun? go to the track.

 

[docjohn]

Dave you last paragraph had me teary eyed....you do get it!!!!:wink:

 

[coolnsx]

Dave you last paragraph had me teary eyed....you do get it!!!!:wink:

That is so well said IMO also.

 

[ScienceofSpeed]

Both are very good systems. Both are very similar as they share many components with the exception of the fuel system. The Comptech / CT Engineering system poses as close to a plug and play system as possible with it's gains limited by the more simplistic fuel system. The ScienceofSpeed Supercharger System uses a larger compressor that produces more power (nearly double), but also requires a more robust fuel system with larger injectors and an engine management system with both fuel and ignition control. Although the engine management system we provide comes pre-calibrated, you must have the car fine tuned on a dyno.

For some, the plug and play nature and CARB certificate (for California customers) is a plus. For others, they prefer the increased in power that our system offers.

If you have any questions, please let us know. For more info:
http://www.scienceofspeed.com/products/engine_performance_products/NSX/ScienceofSpeed/supercharger/

regards,
-- Chris

 

[ScienceofSpeed]

This is a dyno graph comparing a factory engine to a ScienceofSpeed supercharged engine. This is the closest to small block V8 performance you can expect. Note that there is zero lag, unlike even the most efficient turbocharger. Instant power the moment the throttle is depressed:

 

[BATMANs]

Chris,

What sorta A/F ratios are those dyno graphs running at 8psi (& 15psi)?

 

[VegasSpeed]

If I was to buy one I would buy the Science of Speed since it has more bang for the buck. It isn't a cheap endeavor either way. I would recommend buying the intercooler as well since that will save your engine some.

I like Turbo2go's last paragraph as well. However, for me I like having the hp/tq on the straights at the race track. In fact I appreciate my BMW a little more after visiting the track. Nothing beats a good track day.....nothing.

 

[FXMDBilly]

This is a dyno graph comparing a factory engine to a ScienceofSpeed supercharged engine. This is the closest to small block V8 performance you can expect. Note that there is zero lag, unlike even the most efficient turbocharger.

It all depends on SIZE my friend

You can't talk about lag without talking about the whole system: efficiency of the turbo and turbo sizing being very important -as well as: header design and length, Y-pipe sizing, charge pipe sizing, intercooler pressure drop, compression ratio, etc...

Then you have to define "lag" which is just a can of worms.


Billy

 

[ScienceofSpeed]

It all depends on SIZE my friend

You can't talk about lag without talking about the whole system: efficiency of the turbo and turbo sizing being very important -as well as: header design and length, Y-pipe sizing, charge pipe sizing, intercooler pressure drop, compression ratio, etc...

Then you have to define "lag" which is just a can of worms.


Billy

Billy -- please demonstrate a turbo system for the NSX that matches or beats the tip in throttle compressor response of a twin screw supercharger. While each has it's advantages, this is one area where the positive displacement supercharger exceeds.

-- Chris

 

[FXMDBilly]

Billy -- please demonstrate a turbo system for the NSX that matches or beats the tip in throttle compressor response of a twin screw supercharger. While each has it's advantages, this is one area where the positive displacement supercharger exceeds.

-- Chris

A GT30-equipped NSX with a good exhaust and charge pipe design has a big-block V8 or supercharger-like response, even when rolling onto the throttle. The Spoon NSX-R GT that I drove was very well dialed in and tuned with about 400hp and felt as responsive as any supercharged car i've driven. Same goes for the GT30 equipped car of Vega$NSX.

Heck, if you look at the dyno chart from the larger GT35 turboed FX500s of Vega$NSX or COZ's new FX500, at:

3,500rpm:

FX500 (GT35) - ~195whp and ~260-285lb-ft torque
SOS SC - ~195whp and ~260lb-ft torque


4,000rpm:

FX500 (GT35) - ~280-300whp and ~340-400lb-ft torque
SOS SC - ~210whp and ~280lb-ft torque.


These larger turbos are making more power and torque at very low RPM while having the capacity of well over 550whp, cooler intake air temperatures, and instantaneous throttle response above 4-4,500rpm. This GT35 makes as much or more and builds torque and HP substantially more than said supercharger that it may feel like it 'spools up' relative to it's peak power, but in reality, its making just as much or more power that ramps up substantially higher and earlier than said SC -coming from a bigger turbo. Talk to Coz who'se owned and tracked a SC NSX for many years and is loving his new turbo setup that he views as as responsive with amazing delivery characteristics to his old SC setup.

If you're looking for the instant V8 feel at sub 3,500rpm - a smaller GT30 equipped car is the answer and will have that immediate response at the low end, but not capable of flowing as much as the 35 up top. Anyone who'se driven a 335i, Nissan GTR, or 911 turbo (maybe not as much as the previous two) know that 'turbo lag' is all but non-existent and said cars behave and respond to throttle inputs as if they were larger displacement motors. That's what happens with proper turbo sizing.

Their's a lot more to designing a turbo system than just slapping pipes together and connecting them to a turbo. As such, the spool/response/power output, and every performance characteristic can be modified to the desired outcome when designing a turbo kit with the knowledge and background of what each aspect does.

Superchargers are far simpler, easier to install, and a much less involved system. But to criticize turbo's as 'laggy' as a whole is very ignorant. That's like saying "superchargers have no torque in the bottom end" -referring to a centrifugal supercharger that dosn't deliver the immediate torque of a twin screw. It's not accurate to view superchargers or turbos in this way.


Billy

 

[BATMANs]

Since the FD, there has been a few cars and turbo kits that virtually has no turbo lag.

But that's virtually.

I've yet to race or be in any make/model with factory or aftermarket turbos that deliver a positive displacement supercharger results with no lag.

Even the LSx guys will agree with Chris' statements.

 

[NSXCessive]

Since the FD, there has been a few cars and turbo kits that virtually has no turbo lag.

But that's virtually.

I've yet to race or be in any make/model with factory or aftermarket turbos that deliver a positive displacement supercharger results with no lag.

Even the LSx guys will agree with Chris' statements.

I have to add that any well designed Turbo is probably just as good. Would you guys agree that the CT or SOS charger is more plug & play friendly? At least for me thats what I was looking for, and to boot making sure it will pass a surprise side road smog/emissions test.

 

[ScienceofSpeed]

Billy -- This is not what we have found. I have testing on the same equipment to illustrate this.

The following power graph compares the ScienceofSpeed 2.1L supercharger system compared to a single GT35 turbocharger both producing peak pressure of around 8.5 psi (stock engines). The turbocharger system tested was from another respected turbo manufacture which has a very similar layout to the FX system. I also show the pressure curve for your comparison. BLUE = supercharger, YELLOW = turbocharger

This next graph compares the same supercharged car now with a NSX with a built engine (similar CR to stock) and the same GT35 based turbocharger. Although this isn't an apples-apples comparison, you'll see that the below 4000 RPM performance is still better with the supercharger on a stock engine.

For road course use, where the engine will be between 5000-8000 most of the time, the turbocharger system may be better solution. However, these graphs illustrate my point that for most customers with street driven vehicles, the twin screw will be more useful for a majority of driving that they do.

regards,
-- Chris

 

[Oyagi]

That is so well said IMO also.

Boo! If anything the track made me realize how easy it is to top out in an anemic NA NSX. :biggrin::biggrin::wink:

 

[FXMDBilly]

Chris,

As I said earlier, the GT35 will not give the low-rpm torque or hp gains below 4,000rpm like a SC, but from 3,500-4,000 and up, the GT35 (again keeping in mind their are more variables than just the turbo frame sizing like exhaust housing sizing, turbo system layout, y-pipe design, etc...) can equal or better a SC. A more comparable turbo sizing would be a GT30 in the sub 4,000rpm operating range.

Billy -- This is not what we have found. I have testing on the same equipment to illustrate this.

The following power graph compares the ScienceofSpeed 2.1L supercharger system compared to a single GT35 turbocharger both producing peak pressure of around 8.5 psi (stock engines). The turbocharger system tested was from another respected turbo manufacture which has a very similar layout to the FX system. I also show the pressure curve for your comparison. BLUE = supercharger, YELLOW = turbocharger

Again, for the immediate low rpm response and power delivery of a SC or V8-esque, the GT30 is a more comparable turbo. Especially for the 400-450whp range, the GT30 is a much better size than the GT35, as will a GT40 or GT42 (which some NSX tuners use) will have far worse response than even the GT35. Hell, throw a GT28 on there and it might even have more torque at 2,000rpm than the supercharger (but i've never tried it).

This next graph compares the same supercharged car now with a NSX with a built engine (similar CR to stock) and the same GT35 based turbocharger. Although this isn't an apples-apples comparison, you'll see that the below 4000 RPM performance is still better with the supercharger on a stock engine.

For road course use, where the engine will be between 5000-8000 most of the time, the turbocharger system may be better solution. However, these graphs illustrate my point that for most customers with street driven vehicles, the twin screw will be more useful for a majority of driving that they do.

regards,
-- Chris

Agreed. There are people who are actually afraid of revving their cars past 6,000rpm. Maybe its due to driving low-rpm V8s back in the 60s and 70s, or just the fear that motors shouldn't spin that fast. Also for those people who shift at 3,000rpm it's hard to beat the performance of a SC at that low of RPM. For these people, a GT28 might make sense but in the grand scheme of things it would probably be better to go with a SC than to go through all the work for such a small turbo.

For those who track their cars or who aren't afraid of revving their cars out on an onramp or so, said GT30 or 35 turbos will deliver the response and performance equalling or bettering a SC.


Quick 0.02 in laymans terms:

A big turbo like a GT42 might be very laggy below 6,000rpm, but if you're cruising at 6,000rpm+ and punch it, it will be very responsive with minimal 'lag' and will go -very very fast.

A medium turbo like a GT35 can have instantaneous throttle response rivaling a SC at 4,000rpm and above, but rolls into the power band when below 4,000rpm.

A smaller turbo like a GT28 could be instantaneous at any rpm but obviously not flow or make as much power up top.

It all depends on what response, total power output, and all of the hundreds of said factors that affect the characteristic, response, and power delivery of a turbocharged system.

SC are much simpler and great routes to go, but also have their flaws. There are many turbo NSX tuners out there, and they seem to be popping up everywhere. Be sure to do your homework and determine your peak power goals, response, application, and oprating RPM to determine what setup is best for your uses.


Billy

 

[cptnsx]

I think the thing Chris is trying to say as well as all those LSX guys is a turbo will never achieve that linear relationship with the throttle that you get with N/A. A positive displacement supercharger tuned correctly can achieve that. I have driven the new turbo BMW and the GTR and they have that kind of "lag".

Of course when you are running full throttle that "lag" (relationship between the instant you start to feed throttle and perception of that power building progressively) can't be felt esp when the car is powerful or at least ok (off boost) - car goes from powerful to super powerful to uber powerful --- but its still not linear.....but people with turbos like that explosive delivery.

Some people like that linear N/A feeling ----- I know I do and if Honda made an 4.0-4.4 V8 that fit the NSX I would be the first in line for one but my SOS intercooled supercharger (making 416rwhp 315rwtq) is the closest thing we have to that (or ever will have).

 

[3.5lnsxr]

Chris,

What sorta A/F ratios are those dyno graphs running at 8psi (& 15psi)?

batman here is A/F at 15psi

 

[VegasSpeed]

It is very hard to get that quick response from a turbo since the whole engineering behind a turbo means you have to have air moving into the exhaust piping to spin the compressor wheel. So until you have air moving the turbine which then moves the compressor you can't have any boost. So technically there will always be lag. A supercharger is belt driven so when your engine turns the compressor turns, hence no lag.

I have one of each in my garage. The supercharger took some getting used to since it didn't "feel" as fast. It was simply more linear and the turbo was exponential. The supercharger is pretty straight forward though and reliable.

 

[FXMDBilly]

Of course when you are running full throttle that "lag" (relationship between the instant you start to feed throttle and perception of that power building progressively) can't be felt esp when the car is powerful or at least ok (off boost) - car goes from powerful to super powerful to uber powerful --- but its still not linear.....but people with turbos like that explosive delivery.

You are referring to the rapid increase in torque (ramp-up) in a short period of time. You can see this on Chris' dyno chart of the GT35 where the torque jumps 100ft-lbs in 1,000rpm (at 8.5psi). If you are above 4,000rpm, the torque band (in his example) is equally flat to the supercharger. Throttle applications above this RPM (while only delaying a fraction of a second) is instantaneous to a flat torque band and more-linear horsepower increase. You won't have this linear torque or power band at or below this point, but this point can be moved with the turbo sizing -smaller turbos having a flatter torque curve lower in the RPM band. If you want the flat torque band (and wastegates to kick in) at a lower RPM, you need a smaller turbo. Again it all comes down to sizing to get the desired characteristics.

 

[NSXGeek!]

You are referring to the rapid increase in torque (ramp-up) in a short period of time. You can see this on Chris' dyno chart of the GT35 where the torque jumps 100ft-lbs in 1,000rpm (at 8.5psi). If you are above 4,000rpm, the torque band (in his example) is equally flat to the supercharger. Throttle applications above this RPM (while only delaying a fraction of a second) is instantaneous to a flat torque band and more-linear horsepower increase. You won't have this linear torque or power band at or below this point, but this point can be moved with the turbo sizing -smaller turbos having a flatter torque curve lower in the RPM band. If you want the flat torque band (and wastegates to kick in) at a lower RPM, you need a smaller turbo. Again it all comes down to sizing to get the desired characteristics.

I think that's the point being made. For most of us, driving on the street, we're not at wide open throttle al the time up shifting from 8000 RPM - 6000 RPM. The positive displacement supercharger largely mimics a small displacement V8 giving the NSX a more rounded feel. Although it may be closer, even with a smaller single turbocharger, the response will never be as directly rated to throttle input. A smaller turbocharger may be able to get much closer to the response that the positive displacement supercharger produces, but then will choke the system on the top end. Even the twin Bell setup using two GT25s taps out at around 380 whp and still has a moment of lag.

 

[ScienceofSpeed]

Both systems have their advantages and disadvantages. We're lucky do have both a supercharged and turbocharged NSX here at the shop and they both have distinct characteristics. I do believe that for most customers, the bolt on reliability, emissions friendly design (cats are retained), lack of permanent modification required, and overall package of the twin screw supercharger makes the most sense.

cheers,
-- Chris

 

[BATMANs]

SOS supercharger is most suitable for street use.

Start throwing in traffic lights, stop signs and traffic jams and the turbo-boost-tease starts to get really old.

Also, heat soaking from a turbo'd car ads to this problem.

Turbo'd cars are great when the car is constantly moving, as in a wide open freeway.

 

[Ponyboy]

It is very hard to get that quick response from a turbo since the whole engineering behind a turbo means you have to have air moving into the exhaust piping to spin the compressor wheel. So until you have air moving the turbine which then moves the compressor you can't have any boost. So technically there will always be lag. A supercharger is belt driven so when your engine turns the compressor turns, hence no lag.

I have one of each in my garage. The supercharger took some getting used to since it didn't "feel" as fast. It was simply more linear and the turbo was exponential. The supercharger is pretty straight forward though and reliable.

That's about as clear as one can be in the turbo lag debate. And it's a little difficult (read: impossible) to argue against that. Both have inherent weaknesses that you can tune to minimize but the "weakness" is still there and evident.