twin turbo vs. supercharger

[justin hall]

I know we have discussed the differences between Comptech and M superchargers at length, but I dont remember this thread...

Marc, David, and any other turbo's or super’s out there:

· Why did you do twin turbo's vs. supercharge or vice versa?
· What are the reliability differences? I understand the c-tech supercharger is pretty bulletproof. How does that compare to the twin turbo’s?
· Was any consideration given to the fact that c-tech superchargers do not void warranties, but to the best of my knowledge turbo charging does?
· What are the cost differences?
· What are the performance differences?
· I’ve been reading David Allen’s thread about tuning his supercharger, but I have been under the impression they are plug and play. Is tuning a turbo charged system more or less difficult than superchargers?

Thanks, Justin

 

[Forums Nazi]

Start with:

http://www.nsxprime.com/ubb/Forum1/HTML/001442.html

There's also a reference to a good article in:

http://www.nsxprime.com/ubb/Forum1/HTML/001096.html

 

[nsx808]

Turbos give you less of a powerband, but can generally produce more power.

I don't know much about superchargers but owned a Supra TT for a while so I know something about turbos. Basically, the size of the turbo doesn't always mean more power for your specific application. Large turbos have tremendous lag and often don't kick in until very high rpms. This makes them not so good for street use. A good street turbo has moderate lag and a decent powerband. The problem with big turbos is that the power comes very suddenly and it's hard to get traction with street tires. Big turbos are good for drag strips. On an NSX, I would personally use a very small single turbo. Keep in mind that ANY aftermarket single turbo is much bigger than say the turbos on a 300zx or Supra. However, the lag shouldn't be much worse and they are much more efficient. I'm not sure if there's a single turbo kit made for the NSX however.. you'd probably have to take it to a tuner to have it custom done. The good thing about twins is the reduced lag... but on an NSX I would definitely go with a single because you've already got plenty of power at your disposal without a turbo. With a Supra or 300ZX, they're pigs until the turbos kick in.

Hope this helped.. if anyone sees any blatant piles of BS in this rant.. please let me know.

Rob

 

[justin hall]

Originally posted by Forums Nazi:
Start with:

http://www.nsxprime.com/ubb/Forum1/HTML/001442.html

There's also a reference to a good article in:

http://www.nsxprime.com/ubb/Forum1/HTML/001096.html

Thanks, I actully read the first and gleaned some information, althouth it turned into more of a conversation on how to pump HP normally aspirated. I am not really interested in doing that.

I did not read the article David pointed us to. David, would it be possible to scan the article and send to lud for posting? I am sure many of us would be interested in reading it.

 

[ilya]

I don't know much about turbocharging an NSX so correct me if I'm wrong. Since the stock NSX engine can only handle a very low PSI, it would not be cost effective to go with powerful blowers and not utilize what they are meant to do (20-25PSI). The best turbo on an NSX would be the quickest turbo that spools the fastest, because all it needs is 6-9PSI MAX for an NSX. Right?
Unless you start reinforcing the engine so it can handle more and are going for higher horsepower. sound right?

 

[nsx808]

yeah... in the case of 9-12psi.. get a very small turbo and run at it that boost (you can control it with a boost controller). In that case it'll be very efficient and easy on the engine.. also with very little lag

 

[andymlow]

I think turbocharging is the way to go. Look at this site and read the reasoning. I have never owned a supercharged car, but have had many a turbo. Love them.
http://www.bellengineering.net/nsx.html

 

[sjs]

Can't say I agree with all of the above posts. (no offense)

A "good street turbo" has no more lag than an SC system. Turbos need not come on later or have a narrower power band if properly designed for overall performance. If you want max HP for drags, then yes, you may need to accept some lag to get it. However, if you want to add 100-150 HP from a stock block with a VERY wide power band, go with twin small turbos such as the BEGI system. It will get boost earlier than any NSX SC kit, in part because the turbos have a variable vane design and spin up VERY fast. If you can get the fuel delivery right it will provide the best bang for the buck of any kit I've seen, SC or turbo. (it now comes with a Link auxiliary injector controller that does not seem to work with the NSX ECU)

One "very small" turbo can't supply the necessary volume and pressure for the 400+HP you can easily get from the NSX 3.0 engine. If you get a custom single installed by a knowledgeable turbo shop they should be able to calculate your best choice.

In any case, 9-12 psi from a properly tuned intercooled turbo system will put you beyond the safe HP limits for a stock block. 7-8 psi will get you to the safe limit. The SC kits can run 9psi because they make less HP at a given pressure, partly because the are not intercooled.

If you want more info on the current BEGI system, feel free to private me.

Steve

 

[David]

Why did you do twin turbo's vs. supercharge or vice versa?

Had a supercharger and wanted more hp than it was going to deliver.

What are the reliability differences? I understand the c-tech supercharger is pretty bulletproof. How does that compare to the twin turbo’s?

The CT blower kit is probably more reliable, but most of the bad rap against the Bell kit comes from the very early versions that had what turned out to be an inadequate fuel system. The Whipple supercharger that CT uses as the core of their system is probably the best made blower in the world.

Was any consideration given to the fact that c-tech superchargers do not void warranties, but to the best of my knowledge turbo charging does?

Yes. However, if you properly design and tune a turbo, it should not cause any more problems than the blower at the same performance levels. Obviously, to some extant, the more hp you get, the more stress on the system.

What are the cost differences?

Kit vs kit, they are pretty close in terms of cost. If you want to 'improve' the turbo kit and make more power, you will spend a little more money, but get more power than the blower kits will ever make.

What are the performance differences?

Stock vs stock, they are pretty close with a slight edge to the turbos. If you get into modifications, it is no contest - turbos win easily.

I’ve been reading David Allen’s thread about tuning his supercharger, but I have been under the impression they are plug and play. Is tuning a turbo charged system more or less difficult than superchargers?

They are, it will run fine if all you do is bolt it on the way they tell you too. But, if you want to truely maximize it, any forced induction system will need to be tuned to the particular car. That is true of any supercharger or turbo kit on any application.


[This message has been edited by David (edited 01 June 2001).]

 

[nsxtasy]

Was any consideration given to the fact that c-tech superchargers do not void warranties

This is not true. The car's warranty is exactly the same under Comptech supercharger as for any other mod. The car's warranty does not cover any problems caused by any aftermarket mod, whether it's Comptech's or anyone else's. Period.

 

[Lud]

David explained it well. My personal opinion is: If you want a moderate boost in power that you any qualified mechanic can just install and not really have to worry about, get a supercharger. If you enjoy tinkering with things and want to go for a really high power setup, go with a custom turbo setup like David.

I have the SC because I do not enjoy tinkering with things, I enjoy driving. I have no patience for high-maintenance setups or systems that take months to pull together and dial in properly. David's 500+ turbo car is awesome but I would be institutionalized somewhere if I had spent that much time getting my car built up! The reason I have an NSX instead of certain other sports cars is because it is not a maintenace queen. I don't want to turn it into one.

Also, I would never give business to Bell because old Corky basically did his R&D on his early NSX customers. Then when his early kit's lack of proper fuel delivery destroyed their engines, he denied everything and they were stuck with huge headaches, down-time and repair bills.

 

[NetViper]

I read over that bell link on their turbo charging system. They quote 0-60 in 4.4-4.8 seconds with a 1/4 mile at 12.8.

Car and Driver just tested a STOCK 2001 NSX with 0-60 in 4.5 and 1/4 is 12.9.

The bell kit puts out 390 HP vs a stock 97+ of 290 HP and the performance difference is negligible.

Seems like a waste of $9,000 if you ask me.

------------------
NetViper -= looking to get an NSX before I turn 26! =- Didn't make 25

 

[justin hall]

Originally posted by NetViper:
I read over that bell link on their turbo charging system. They quote 0-60 in 4.4-4.8 seconds with a 1/4 mile at 12.8.

Car and Driver just tested a STOCK 2001 NSX with 0-60 in 4.5 and 1/4 is 12.9.

The bell kit puts out 390 HP vs a stock 97+ of 290 HP and the performance difference is negligible.

Seems like a waste of $9,000 if you ask me.

I dont think that is an apples to apples comparison. I bet the performance numbers quoted were 3.0l. Also, the C+D numbers were the most aggressive I have seen, all conditions must have been ideal.

 

[ilya]

I agree. I got a chance to ride in a 9PSI supercharged NSX and it made my car feel like a Civic. It pulled as hard as when I hit the NOS, maybe even more.
I always questioned it's worth at 10K, but after taking one ride I was ready to fork over the dough. Good thing I didn't have it.

 

[SpeedDemon]

Justin:

David's answers to your questions pretty much sum it up for me as well.

I agree with Lud regarding the 2 scenarios he mentioned (easiest install/maintenance = SC, most power/lots of time & tweaking = custom turbo). But, there's a third scenario which is the one I have - a twin turbo kit. The TT kit falls in between a Comptech Kit and a custom turbo setup, and is closer to the Comptech side of things. It does not require much in the way of customization and tweaking as it IS a kit and not a custom install. We spent a total of about 2.5 to 3 days installing the kit (One long Friday night, and 2 Saturdays.)

Re: turbo lag, the twin turbo kit is no more laggy than an SC kit, and in fact should produce boost earlier (at low rpms) than an SC since the turbo will respond to engine load whereas the SC only responds to what RPM you're currently at.

My turbo system is currently set at 4psi, so there's a touch more lag right now compared to when I raise to 6psi (the boost-reduction mechanism has to kick in earlier to slow the turbos as they reach 4psi, adding more "lag"), yet when I repeatedly raced Sam's Comptech SC car with the "9 lb" kit there was NO difference in response between our two cars no matter what gear we raced in.

Originally posted by NetViper:
I read over that bell link on their turbo charging system. They quote 0-60 in 4.4-4.8 seconds with a 1/4 mile at 12.8.

First off, numbers will always be different between two sources for the IDENTICAL car. Some guy or customer at Bell Engineering testing the car and coming up with those #'s vs. how a magazine tests a car is guaranteed to give you different results.

On top of that, the cars you mentioned weren't at all identical. The Bell #'s (which are several years old) were for a 3.0/5 speed NSX, a car that tested in the mid 14's for the 1/4 mile. The magazine #'s you quoted were for a new 3.2 6 speed and are generally acknowledged as seeming on the aggressive side.

If you want before & after numbers, check out the FAQ or put a request in to the FAQ Nazi

, you'll find a couple different NSX'ers posting low 12 second (12.3) 1/4 mile times after installing a Bell TT kit on their 3.0 cars..

>Why did you do twin turbo's vs. supercharge or vice versa?

I don't want to start another Turbo vs. SC debate, so just consider the following my beliefs/opinions..

Several reasons... The first was power. The dyno charts I've seen for most SC cars simply didn't look as nice as the dyno's for the Bell TT cars. The Bell TT kit gives you more power at a lower boost setting. This is possible because they are more efficient, they don't leech much horsepower like a belt-driven SC does, and they put out cooler air (twin intercoolers are included in the kit). Also, I generally saw faster 1/4 mile times posted by TT guys compared to SC guys, which seemed to back up my belief that the TT kit has a better powerband.

Next was cost. On the surface, the cost of the TT kit seems similar to the cost of an SC kit (with the exception of the Comptech kit for a Targa car, which is priced noticeably higher, at ~$11K!). But when you look deeper you find the TT kit includes dual intake systems, and the complete exhaust system. You would still have to buy those for the SC system, and that's nearly another $2000.

My targa top played a role in the decision too. You can't have a targa top holder with the Gruppe M setup, and the Comptech one requires you replace the factory one with their cheaper version (and as mentioned, it's much more expensive than their non-targa SC kit).

I'm also smog-paranoid, and I like stealth. The TT setup is very stealth compared to any of the SC options. The engine compartment can be made to look totally stock to the average person/police officer. There's good potential the car could pass the visual for the smog test too given past experiences with the NSX.

Those were the main reasons, there were various other smaller reasons too (ability to adjust boost to higher or lower levels, it's nice to have something "different", my past few cars have been turbo, etc).

As I've said in the past though, I still recommend an SC kit for most NSX'ers, the TT kit is really only useful for the small # of NSX'ers who want to push the power limits more and don't mind "getting into the details" (or have a great tuner near them they can trust to take care of the details).

Hope this helped!

Marc
97 NSX-T Twin Turbo

 

[sjs]

Originally posted by SpeedDemon:
Justin:... Marc 97 NSX-T Twin Turbo

What he said!

Really, Marc pretty much covered it for me too. I would re-stress that the TT option allows you to achieve the max safe HP for a stock block, it delivers the increase over an incredibly broad range, and it is easily adjusted up and down. I've yet to see an SC system that can touch it for my $. However, I do have gripes of my own that I won't further expound upon here.

 

[David Allen]

You've seen my posts about my disappointment in the numbers relating to the $16K worth of mods that I did (SC, Intake, Headers, and Exhaust). However, the truth is that it IS a different car - the car that it should have always been. It's a whole new animal, and I absolutely love it - I was just upset because the numbers didn't come out to be what I anticipated. The mistake that I did was that I did not dyno it before I installed anything, so I don't have a baseline to work from. However, if I do use the 'average' 3.2L baseline from Technodyne, which is around 230RWHP, then I gained ~100RWHP with the modifications, which is what Comptech advertises. I'm going to hand my car over to Mark Basch this month and let him work on the car a bit to make things a little more efficient (fuel system, etc.) - we're anticipating ~15RWHP from the modifications. I'll be sure to let everyone know how it goes.

Truth be told, if I took my car to Comptech's dyno today, perhaps it would register ~360RWHP - I don't know what variables they use - but that's because they stated the car STARTED with 260RWHP stock.

I've learned that it's not really the starting and ending numbers (because all dynos can be so different), but the difference between the baseline and the result.

I highly recommend going with the Supercharger. I also recommend the Intake, Headers, and Exhaust. For $4.5K it only gave me ~15RWHP, but the sound of the intake (hissing as it brings in air), and the exhaust is great. I'm not sure how much the Comptech headers give over the stock 3.2L headers, but the guy at the dyno was only expecting ~8RWHP from the whole setup, so he was surprised...

------------------
David Allen
'00 Silverstone NSX-T

 

[justin hall]

thanks for all the responses. one more question:

Once you get the supercharger or turbocharger dialed in, do either require continuous tuning? Assuming other variables stay the same such as elevation and fuel...

Given I already have c-tech headers, exhaust and airbox, Lud's ethical point (important to me also), and my lack of desire to tune, I am leaning toward supercharger. However, if you only have to tune once....

Thanks

 

[nsxtasy]

There are two articles, one about superchargers and one about turbochargers, in the new issue of Sport Compact Car.

 

[SpeedDemon]

Originally posted by justin hall:
Once you get the supercharger or turbocharger dialed in, do either require continuous tuning? Assuming other variables stay the same such as elevation and fuel...

Given I already have c-tech headers, exhaust and airbox, Lud's ethical point (important to me also), and my lack of desire to tune, I am leaning toward supercharger.

Once you're dialed in, you're dialed in, for either system. You don't have to tune further, unless you add/remove performance parts (or you come to suspect you weren't optimally tuned to begin with!).

A supercharger is probably your best bet, particularly because it will make the most of the mods you have. Adding a turbo system will replace your current intake and exhaust mods, but those components can be kept as-is if you go with an SC system.

Good luck!

Marc
97 NSX-T Twin Turbo

 

[Bruce]

First off supercharging, turbocharging and even Nitrous Oxide are accomplishing the same results. Compressing(boosting) more oxygen than normally aspirated into the combustion chamber, so when ignition occurs the explosion of air/fuel mixture is much greater which creates more power. How they are able to accomplish this is the difference, cost to operate is another. Nitrous produces boost but at a cost of constantly refilling. SC at a cost of taking power to make power. TC uses the exhaust gases which at this point is not worth anything and is just being expelled out the tail pipe already.Heck, that should acredit you for at least being environmentally conscious. hahah
The NSX has it all,... looks,comfort,reliability,handling,and power. But the VTEC power really doesn't come on til past 5000rpm.What the NSX lacks is, low end power or drivability.The myth of SuperCharging being more responsive to TurboCharging is FALSE. the SC output is solely limited based on RPM and how fast that RPM climbs. In other words...more RPM equal more boost.Again in the NSX, nothing happens til 5000rpm and the same for a SC.This is one reason why the taller gearing is recommended. SC have better results on engines which have good low-end already, but I would still choose TC over SC for many reasons. Turbos are based on load so you'll get boost when you need it most, regardless of RPM. Because SC are solely based upon RPM you will have boost even when you don't need it.With TC when just cruising, say...4500rpm on the highway, because there is no load there is no boost. SC on the other hand will always be in boost which in turn consumes more fuel because of boost sensitive fuel pressure regulators, this also create excessive strain on other parts.(especially the ones with gears)SC are usually driven by a belt/pulley system involving crank pulley,water pump,alternator,etc... This puts increased load on their bearings. This increased load also robs you of power,I think it's referred as parastatic loss.TC also create less stress on Automatic Transmissions.... in between shifts there is no load therefore no boost.
I chose the TT kit for the many advantages over the SC kit...but to clarify, I think you're referring to the BEGI kit which consist of Aerodynes patented Aerochargers. Unlike turbos, these Aerochargers are self-lubricated which allows them to be mounted virtually anywhere and almost any position.Turbos must be mounted above oil level and some what perpendicular to ground level.Aerochargers also have what is called variable vanes which eliminates the inherent "turbo lag". Although they don't generate the horsepower as turbos do in race cars,....I don't think we're talking about race cars, we're trying to build a street car.
I've haven't touched the Aerochargers and haven't experienced any other problems since installing them in end of 1998.Today,I'm still amazed with their performance,and plan on using them in other applications.
As for the SC issue on warranty....if a problem does arise which is related to the SC, it is not covered by Acura but by Comptech.You must read the fine print.Taking nothing away from C-tech, the bulletproof reliability factor SC or TC should be credited to Honda/Acura.The NSX is built so well is why the results are so favorable.Other than that,I really can't think of ANY advantage the SC has over the Twin Aerochargers.

 

[sjs]

A bit of clarification for those not familiar with the Aerochargers. Aerocharger is really just the trademark name for a particular brand of turbo changer, albeit a very special one. As noted correctly above, they are self lubricating (no oil lines from the engine) and they utilize a variable vane system that allows them to spool up quickly like a very small turbo, but still pump the volume/pressure of a (somewhat) larger one. However, in other respects they look and function like any other turbo.

BTW Bruce, you say you haven’t touched them since 1998, but I trust that you change the oil in them as recommended. Also, what auxiliary fuel management system do you use? (have I asked you that before?)

[This message has been edited by sjs (edited 06 June 2001).]

[This message has been edited by sjs (edited 06 June 2001).]

 

[nsxtasy]

the VTEC power really doesn't come on til past 5000rpm.

in the NSX, nothing happens til 5000rpm

These two statements are not true. VTEC does not ADD acceleration after 5000 rpm; it prevents acceleration from falling off.

Remember, acceleration results from torque at the wheels, which is torque in the engine multiplied by gearing. Within any particular gear, torque is fairly flat, which means acceleration is fairly constant, at all revs (and doesn't fall off much until you start getting close to redline). We saw this recently with someone's g-analyst acceleration curves posted on the forums.

The advantage of VTEC is that it prevents torque from falling off as revs increase, and as a result, you can rev higher without needing to upshift. (Upshifting robs power because of the effect of gearing on torque at the wheels, and hence, on acceleration.)

 

[Bruce]

BTW Bruce, you say you haven’t touched them since 1998, but I trust that you change the oil in them as recommended. Also, what auxiliary fuel management system do you use? (have I asked you that before?

Actually I was told to just add oil, which I have done, but changing the oil now would be a good idea,Thanks. Do you have any suggestion on what type of oil to use.I'm out of the original aerocharger oil which was clear, I was talking with Marc in regards to his set-up and found his to be red in color....or are they just re-bottling RedLine and charging even more for this so-called special Aerocharger oil.
I used the RebicIII in the NSX and my old RX-7 Turbo with excellent results.Marc is using the RebicIV. I've lately been using the HKS AIC(AdditionalInjectorController)in the Turbo Supras with excellent results.The AIC can handle high or low resistance injectors, but choosing the HKS was for reasons not performance related.I generaly prefer to use only Japanese hardware for most mods.

These two statements are not true. VTEC does not ADD acceleration after 5000 rpm; it prevents acceleration from falling off.

To me it's true. I was just saying the NSX IS SLOW under 5000RPM.After that the VTEC turns on and adds more power.(prevents acceleration from falling off)Without the VTEC the NSX would not be able to effectivly accelerate after 5000RPM so it does add acceleration. This has nothing to do with gearing....the characteristics of the engine doesn't change in relation to gears.
VTEC (which stands for Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts. As the engine moves into different RPM ranges, the engine's computer can activate alternate lobes on the camshaft and change the cam's timing. In this way the engine gets the best features of low-speed and high-speed camshafts in the same engine.

 

[nsxtasy]

Thanks for the clarification.

Some people think the car actually accelerates more quickly in the VTEC range than at lower revs - probably because it sounds louder - but it doesn't.