Market for used Comptech Superchargers ??

[nsxtasy]

I don't know if sales are limited to those installed by Mr. Basch, but I do know that he is more than happy to fly across the country to other locations to install the BBSC and do other NSX work.

[NSXTC]

I think the plan will be to have distributor/installers in other parts of the country as well. Not sure exactly how that will play out, but I’ll bet that once all the dust settles and everyone already signed up gets theirs, the geographical issue should not be a barrier. Who knows, I’ll bet we see dealers installing the BBSC’s in the not too distant future, as the install is easier and less involved than the CTSC install.

Why would someone who owns a CTSC switch to a BBSC? Well, the way I see it is that the high-boost option CTSC still gives better low end grunt than the standard BBSC. This could be seen as more desirable for guys who like to run weekend track events, because you can get better pull coming out of those turns running between 5-7,000 RPM.

The BBSC has bigger lungs than the CTSC and can get us a better max HP number, it just takes a bit longer to ramp up than the CTSC. That, in a nutshell is the big difference for most guys. Forgetting about the price difference for a moment, the decision comes down ultimately to a matter of driving style and personal preference.

The story does not end there, however. One of the real advantages with the BBSC is that (to borrow a computing term) it is more scalable: you can set one up to run much higher boost numbers than you can with the CTSC. An old axiom is that no matter how much power your car makes, you will eventually get used to it, and start wanting more.

I predict that in the near future we will start seeing some enthusiasts (I myself have already taken the plunge) trading in their used CTSC’s, and opting for some higher boost numbers (10-14 PSI) with the BBSC in conjunction with the required internal engine work. I see nothing wrong with otherwise keeping the CTSC if you already have one. It’s a great kit, but the high-boost / engine rebuild option was just too tempting for me. After all, 1991 models are now flirting with official automotive antique status (12 years old), and many guys wanting to keep their cars long term would not mind getting their motors rebuilt at this point anyway.

[nsxtasy]

Originally posted by NSXTC:
1991 models are now flirting with official automotive antique status (12 years old)

In Illinois, at least, official automotive antique status isn't reached until 25 years old.

[cojones]

Originally posted by NSXTC:
Well, the way I see it is that the high-boost option CTSC still gives better low end grunt than the standard BBSC. This could be seen as more desirable for guys who like to run weekend track events, because you can get better pull coming out of those turns running between 5-7,000 RPM.

The BBSC has bigger lungs than the CTSC and can get us a better max HP number, it just takes a bit longer to ramp up than the CTSC. That, in a nutshell is the big difference for most guys. Forgetting about the price difference for a moment, the decision comes down ultimately to a matter of driving style and personal preference.

This is an interesting assertion. If its accurate, then it implies that for a lot of STREET driving, a 9-lb CTSC may actually give a preferred performance curve, and may be the price-independent choice.

Extending the assertion, would it be reasonable to expect that BBSC shines more in higher-end RPM work (straightaway speed, and those who do stunts like the Silver State Classic), and less so in the 5-7K range ??

If the datapoints are available, I'd be interested in seeing these SCs compared on Bob Butler's worksheets.

###########

BTW, I totally buy the argument on scalability... for one who wanted to develop higher-boost applications, BBSC (or possibly an intercooled GMSC) seems to be the way to go, at least amongst currently-available alternatives.

[Yellow Rose]

Please, let's not degenerate this great supercharger thread with antique car status.

[Yellow Rose]

I think NSXTC and cojones bring up a valid point, that the CTSC comes into play sooner in the RPM band then the BBSC does.

That said, something we haven't discussed much on this thread is gearing. Would it be correct to state that folks with short gears and / or R&P would benefit more with the BBSC, since they will be at a higher RPM?

I have heard more than one time that the CTSC has more low end grunt that the BBSC. From an engineeering standpoint this does make sense; however, I'll be honest - I get caught up in HP curves and often forget about torques curves. Quite perhaps the CTSC torque curve is more appealing at lower RPM than the BBSC torque curve. Torque is what accelerates a car. HP maintains the top speed which is a function of aerodynamic drag.

The CTSC is based on a Whipple blower; whereas, the BBSC is based on a Paxton blower. As energy conversion devices, they do the same thing - increase pressure - but do so on different principles. The Whipple is a positive discplacement (PD) blower and the Paxton is a centrifugal blower. The laws of Fluid Mechanics states that the efficiency of a PD machine is ALWAYS greater than its centrifugal counterpart. Note that I said *more efficient* which does not mean more boost. By design, a PD blower does have limited boost potential. On the other hand the centrifugal blower has lower efficiency because of internal aerodynamic losses. Sorry, nothing we can do about Mother Nature.

So, what do we have? CTSC = Whipple = PD = higher efficiency with lower boost. BBSC = Paxton = centrifugal = higher boost (potential) with lower efficiency. For all intents and purposes, the two units develop order-of-magnitude comparable power output at similar boost levels.

Which is better? One is half (for now) the cost of the other but is not legal (for now) in the state that has the most NSXs and the other has been in service being enjoyed by NSXers for several years now. One is installed only in the Southwest (for now) and the other can be install anywhere. Pick one, there is no wrong answer. Thus the conundrum.



[This message has been edited by AndyVecsey (edited 05 April 2002).]

[nsxtasy]

Originally posted by AndyVecsey:
Would it be correct to state that folks with short gears and / or R&P would benefit more with the BBSC, since they will be at a higher RPM?

No, not really.

The use of a shorter R&P does not change the rev band whatsoever. When you accelerate to redline and then upshift from one gear to the next, the revs will drop to exactly the same point with the shorter R&P as they did with the stock R&P.

Compared with the stock five-speed, the short gears change the rev band but only slightly overall. They shorten the revbands for second gear (changing it from 4433-8000 to 5013-8000) and third (changing from 5698-8000 to 5705-8000), while lengthening the revbands for fourth (changing from 6262-8000 to 5824-8000) and fifth (changing from 6284-8000 to 5983-8000).

[Sig]

Ken-

If the rev band is lengthened on the top gears, then is it safe to say the top speed is not affected by short gears?

[Yellow Rose]

Short gears apply only to 2nd, 3rd, 4th - top speed is not affected.

BTW - my question was more along the lines of gear with respect to BBSC vs CTSC, not gearing in general.

[nsxtasy]

Originally posted by Sig:
If the rev band is lengthened on the top gears, then is it safe to say the top speed is not affected by short gears?

No. With the short gears, the rev band in fifth is lengthened at the low end, the rev point where you wind up after upshifting from fourth. The top speed (which occurs in fifth gear) is not affected.

Incidentally, even though I indicated that the revband in fifth extends to 8000 rpm - it does, but you can't reach it with a stock NSX because top speed is drag-limited to 168 mph.

Short gears apply only to 2nd, 3rd, 4th - top speed is not affected.

Top speed is not affected, but the revband in fifth is affected. Even though the short gears don't use a shorter fifth gear, the shorter fourth gear affects the number of revs you turn in fifth gear after upshifting from redline in fourth.

[RACERnsX]

[QUOTE]Originally posted by AndyVecsey:
[B]I'd pay AT MOST 50% of a BBSC for a 9 PSI CTSC kit. IMO the 9 PSI CTSC provides less value than BBSC, and cannot be sold for more.

Is this the first of many? It will be interesting to see what this brings:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1828099162

[Yellow Rose]

For the record, in the above post, I am misquoted. Those words were by COJONES, who replied to my post back in April.

To answer RACERnsx's question - yes, this will be the first of many. Hint.



[This message has been edited by AndyVecsey (edited 13 May 2002).]

[nsxhk]

Hmmmm.....

Is it true that you can still drive the car with the bb supercharger belt removed?

Is it true that you cannot drive the car with the CTSC belt removed?

If both of the above is true, I'd rather go for the more economical BB cuz I don't want to be stranded in the middle of nowhere.

[ilya]

I recall hearing somewhere that you can drive the Comptech without the belt.

[NSXTC]

You can drive the CT without the belt, but only for about 30-45 minutes, which is when the battery (and hence the car) dies. Ask me how I know!