Twin Turbo or Supercharge??? Need your opinions

**TheSwishh** · 08-06-2002, 03:18

OK, I have the Bell/TT system for my 91. I have the chance to switch to the BBSC and want to know what you all have to say. Should I stay and be happy with what I have or should I get greedy and go for the huge numbers that the BBSC is putting out? I still have a lot of fuel issues to resolve with the TT but find myself wondering if I will encounter the same issues with a superchager as well???

I have just destroyed two stock pistons from the TT and am now running all JE Pistons. I would like to think that I have a "bulletproof" setup now but I am still a little shy of the TT.

ANYBODY???

**nsxtasy** · 08-06-2002, 06:18

I would think this is a very personal decision. At the time you decided to go for the Bell/TT system, I assume the Comptech SC was already on the market. Presumably there were reasons you wanted the Bell/TT - different power delivery characteristics, or perhaps just the challenge of making something unusual work. Whatever those reasons, are you still happy with that decision? If you are, and you're looking forward to working through the fuel issues, then go for it! If you're spending every minute regretting the day you got it, then it's time to ditch the TT system; I assume you can still get some significant money out by selling it.

If the money is an issue, you're weighing an unknown amount to make your system work against a known amount to get the BBSC. Once again, a personal decision that no one else can make for you.

**MAJOR STONER** · 08-06-2002, 06:44

I don't have anything intelligent to add, but I did turbocharge a Porsche once, and most of my problems were heat related. I can't imagine what two turbos do (dual stage set-up?) but the heat must be an issue. I am surprised that your fuel isn't boiling, I know boaters that ice down their fuel lines to make the fuel more dense. I think that supercharging may be easier on the engine and easier to tune for.

**true** · 08-06-2002, 09:01

Originally posted by MAJOR STONER:
the heat must be an issue. I am surprised that your fuel isn't boiling, I know boaters that ice down their fuel lines to make the fuel more dense. I think that supercharging may be easier on the engine and easier to tune for.

A heatercharger, er supercharger, will produce much higher intake temperatures then a properly designed turbocharger system any day of the week (including weekends.. :]) under any condition.

EDIT: Swish, I would keep the twin turbo setup. Those aerodynes are no match for any supercharger system.
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jack of all trades, master of some.

[This message has been edited by true (edited 06 August 2002).]

**Jimbo** · 08-06-2002, 09:18

"...A heatercharger, er supercharger, will produce much higher intake temperatures then a properly designed turbocharger system any day of the week (including weekends.. :]) under any condition...."

Really?

That sounds counter-intuitive.

Why is that?

You would think that routing hot exhaust gases through one side of the air pump (as opposed to not routing hot exhaust gases) would make the supercharger approach much cooler all the way around.

-Jim

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1992 NSX Red/Blk 5 spd #0330
1991 NSX Blk/Blk Auto #3070 (Sold)
1974 Vette 454 4 spd Wht/Blk
http://homepage.mac.com/jimanders/PhotoAlbum1.html

**Number9** · 08-06-2002, 09:29

The centrifugal SCs are similar in efficiency to turbos, so they should heat the intake air similarly under similar levels of boost. The turbo has a huge advantage in that the turbo can spool up independent of motor RPM and can bring more boost on sooner. Also, the turbo is using waste exhaust gas to spin up, whereas the SC has direct mechanical linkage that causes more parasitic HP loss. True, I presume you meant that the aerochargers are more than a match for any supercharger system...

[This message has been edited by Number9 (edited 06 August 2002).]

**emvanderpol** · 08-06-2002, 09:45

Just curious,

Does anyone know how much h.p. the SC drains off of a 6 psi system. It would be interesting to know the thermodynamic efficiency of the Turbo versus the SC. Notwithstanding the fuel issues, this should be the deciding factor in determining which system would generate greater steady-state power.

**ScienceofSpeed** · 08-06-2002, 10:15

What destroyed the pistons? Engine running lean?

Originally posted by TheSwishh:
OK, I have the Bell/TT system for my 91. I have the chance to switch to the BBSC and want to know what you all have to say. Should I stay and be happy with what I have or should I get greedy and go for the huge numbers that the BBSC is putting out? I still have a lot of fuel issues to resolve with the TT but find myself wondering if I will encounter the same issues with a superchager as well???

I have just destroyed two stock pistons from the TT and am now running all JE Pistons. I would like to think that I have a "bulletproof" setup now but I am still a little shy of the TT.

ANYBODY???

------------------
Revolutionize your NSX with ScienceofSpeed
www.ScienceofSpeed.com | [email protected] | 877-863-4520

**Gerry Johnson** · 08-06-2002, 10:22

I would go with the Turbo, they are very easy to work with and they make better usable HP and torque through out the entire RPM range. Compare the dyno runs of the Turbo to the SC dyno runs, their is over 100 HP more at 5000 RPM with the Turbo. You can see the Turbo dyno run in the forum heading
Dyno sheet from the PA NSX

[This message has been edited by Gerry Johnson (edited 06 August 2002).]

**Jimbo** · 08-06-2002, 10:30

Number9,

I understand about parasitic losses and efficiencies, I just wanted to know how "true" came up with the intake temperature argument. I don't think it's accurate.

-Jim

------------------
1992 NSX Red/Blk 5 spd #0330
1991 NSX Blk/Blk Auto #3070 (Sold)
1974 Vette 454 4 spd Wht/Blk
http://homepage.mac.com/jimanders/PhotoAlbum1.html

**ilya** · 08-06-2002, 10:48

Reliability aside, I have yet to ride in any Supercharged NSX that accelerated and put down the torqe a Bell turbo does. You would have to go built motor and high boost with a Supercharger to produce better numbers than the turbo. The turbo will always be more efficient and also produce considerably more torque at low RPMs than any supercharger.

There are other issues of course such as maintenance and reliability. For performance purposes alone, I would personally never drop a turbo for a supercharger. There is still only 1 NSX I know of with a stock motor that broke into 11s in the 1/4... and it was the BellTT.

Finally, the decision depends on your planned use of the car. If you plan to track it a lot, in hot weather and for long periods of time, a dependable SC like the Comptech or BB would be a better decision.

**nsxtasy** · 08-06-2002, 11:02

Originally posted by nsxtasy:
I would think this is a very personal decision. At the time you decided to go for the Bell/TT system, I assume the Comptech SC was already on the market. Presumably there were reasons you wanted the Bell/TT - different power delivery characteristics, or perhaps just the challenge of making something unusual work. Whatever those reasons, are you still happy with that decision? If you are, and you're looking forward to working through the fuel issues, then go for it! If you're spending every minute regretting the day you got it, then it's time to ditch the TT system; I assume you can still get some significant money out by selling it.

If the money is an issue, you're weighing an unknown amount to make your system work against a known amount to get the BBSC. Once again, a personal decision that no one else can make for you.

Hey, how come nobody's accusing me of abandoning the position of which I have sometimes been accused, that stock is always best no matter what?

Maybe it's not as rigid a position as sometimes alleged...

**anvil** · 08-06-2002, 11:49

xtasy,

I believe the stock answer is

"It would be a waste of time."

(Forgive me, I have sinned, but I just could not resist the urge.)

**true** · 08-06-2002, 12:05

Originally posted by Jimbo:
Number9,

I understand about parasitic losses and efficiencies, I just wanted to know how "true" came up with the intake temperature argument. I don't think it's accurate.

-Jim

? I don't see any argument. I haven't seen a SC kit with an intercooler. It was NOT meant to be a universal turbo vs supercharger fact. Maybe I should re-word it...Major stoner said he though heat would be a big problem with using a turbo...i would be very suprised if the gmsc,bbsc,ctsc came close to the IAT of the TT kit. His post is asking which he would keep. When you have a SC system replacing/bolting to the intake manifold theres not much you can do with the air.

Has anyone measured any air temps for their FI setups?

**true** · 08-06-2002, 12:10

Originally posted by nsxtasy:
Hey, how come nobody's accusing me of abandoning the position of which I have sometimes been accused, that stock is always best no matter what?

Maybe it's not as rigid a position as sometimes alleged...

Didn't you put aftermarket shock absorbers in your car????????????????????????????? I'm telling Honda.

**MAJOR STONER** · 08-06-2002, 14:02

"MB has said that in
recent tests, engine compartment temperatures in the NSX can reach 270 degrees or more at the air filter box
location." I'd be interested in what the temperature under a TT's engine cover, got a cooking/oven gauge you can tape on before a strong run?

**ilya** · 08-06-2002, 14:04

The Vortech supercharger on George Peniche's NSX is liquid intercooled.

**SpeedDemon** · 08-06-2002, 14:28

Swishh:

Unless someone's said something here which really entices you to want an SC setup then stick with the twin turbo. You'll be faster and have more usable power down low, and you'll do it running less boost than the SC systems.

Blowing an engine/pistons is almost always the result of detonation. If you haven't corrected your fuel problems then your new engine is likely to get blown too even if it's been built stronger than the last.. Probably best to keep your foot out of the gas for now...

Assuming you run a reasonable boost level (say, 6psi and under) and your system is in good working order, there's no reason you can't run your system reliably with the right fuel components.

Several of us here can help you work out the fueling problems you might have (I think we've started to do so on the Technical forum). I hadn't seen your post here that you had blown an engine before.. Now that I know, I'll take another look at the thread on the tech forum, this time with an eye towards making sure you're really covered on fuel for your setup.

On a final note.. You aren't being greedy by "going for big numbers with an SC system". You are just not seeing the whole picture. Peak horsepower doesn't mean much. It's the torque curve that matters, and that's where the twin turbo system really shines. My system isn't set up for peak horsepower at all, but it's pulling 119mph trap speeds in the 1/4 mile on 91 octane pump gas.

Best,
Marc

**Jimbo** · 08-06-2002, 14:47

True,

You didn't answer my question...How did you come up with this statement?

"...A heatercharger, er supercharger, will produce much higher intake temperatures then a properly designed turbocharger system any day of the week (including weekends.. :]) under any condition...."

Argument, position, theory, or whatever, I'm just curious how you arrived at this conclusion. You seemed pretty darn sure and I'm just wondering how this could be?

-Jim

------------------
1992 NSX Red/Blk 5 spd #0330
1991 NSX Blk/Blk Auto #3070 (Sold)
1974 Vette 454 4 spd Wht/Blk
http://homepage.mac.com/jimanders/PhotoAlbum1.html

**true** · 08-06-2002, 15:06

Originally posted by Jimbo:
True,

You didn't answer my question...How did you come up with this statement?

"...A heatercharger, er supercharger, will produce much higher intake temperatures then a properly designed turbocharger system any day of the week (including weekends.. :]) under any condition...."

Argument, position, theory, or whatever, I'm just curious how you arrived at this conclusion. You seemed pretty darn sure and I'm just wondering how this could be?

-Jim

I don't have a formula? Is that what you are looking for? I'ts just personal experience with different supercharger and turbocharger systems...it's my 'theory' or whatever you want to call it. Like i said in my previous post, it's not to be taken as fact. I have found the turbo IAT to be much lower all the time...but no, I don't have every combination of every car. Sounds like you want me to admit that i dont have experience with the stated NSX systems. Ok, I don't; I just have a good hunch.

Does anyone have any intake temps for ctsc, gmsc and belltt? Sjs maybe?

**Gerry Johnson** · 08-06-2002, 17:44

With the Bell turbo kit your under engine cover temp would almost be that of a stock NSX, all the Turbo's and all piping are under the back of the car,intercooler's mounted behind each rear wheel. On my single Garrett turbo NSX the MAT is 50 degree's C under long runs at 15 lbs of boost and at cruise it is between 16 and 20 degree's.

**sjs** · 08-06-2002, 19:18

As Gerry just said, the design of the Bell TT is ideal from a temperature standpoint. The one thing he didn't mention is that the air filters are up inside the rear quarter panels, away from the turbos and the normal engine compartment heat. These placements may have other drawbacks (aluminum intercooler mud flaps, more weight shifted towards the rear for example) but it seems to work as a reasonable compromise.

Back to the original question. Most of my views have already been expressed by those who have noted the advantages of each option. However, the latest wrinkle in the situation is the apparent demise of Aerocharger. Hopefully someone (possibly the new Cartech guys) will pick up at least the turbo maintenance, but that may not be practical and almost certainly limited to remaining parts inventory. In other words, you have somewhere between 1 and 100k miles before the turbos fail and can’t be replaced with an equivalent item. By then Cartech may have a retrofit kit for conventional turbos, but that may be my signal to start over.

I too am interested in hearing more about your blown engine. Did I get an email from you recently? Or perhaps I saw a question in another thread about the Cartech sale. Are you using the solenoid to cut off the vacuum line to the MAP sensor. I’ve come to believe that it is responsible for some of the past disasters with the kit. It woks fine on a dyno and whenever shifts are slow, but in real world conditions when you shifthard and fast it can trap vacuum in the line, which reduces the output of the stock injectors at the worst possible time.

**TheSwishh** · 08-07-2002, 03:44

EVERYBODY!!!

I must thank you all VERY much for taking the time to help me resolve my "personal dilemma." I found every reply to have great foundation for helping me to decide!

As for the blown motor, I cant really say what caused it??? I never heard any detonation and the dyno A/F numbers were pretty steady around 11-12's. I had 80K miles on the car / 20K of them Turbo'd but we all know that 80K isnt anything to these motors. It must have been that "little lean gremlin" eating away at the pistons and I never even knew it. It all began when I started to get a little bit of blow by. I then did a leak down and found that it was ring or piston failure. I dropped the motor and found that the furthest pistons from the intake had small cracks on the sides of the piston walls. The rings were still in great condition and the faces of all of the pistons were in excellent condition. No pits or any signs of detonation. It is still a mystery.

sjs, you have been a great deal of help and once again I must thank you for all of your input in the "Technical Arena." I am just wondering what in the heck went wrong and wonder if its worth the risk once again?

I supose I am a victim of the "I want my cake, and I want to eat it too" syndrome.

I see the new BBSC numbers at over 400RWHP (beating mine) and want it, but then I see that I have greater TQ numbers and know that this is were the true power is... or thats what I keep telling myself.

Either way, all of the input I got from you guys has proven to me that I should give this thing another chance. I must say that I am surprised though... I thought most of the NSXPrime folks were PRO-SC people?!?

I think nsxtasy said it best when he asked what made me choose the TT kit over an SC in the first place. Question answered... to have the BEST! Thanks Again!

**anvil** · 08-07-2002, 18:31

Swishh,

I described your problem to my tech, who is a pretty savvy guy. His guess was detonation in the affected cylinders because of an inequity of pressure in the "plenum" that distributes air to the ports. Probably not, but if the cause is "a mystery" still then perhaps this is a useful speculation.

anvil