BaschBoost performance numbers???

[Attitude Adjuster]

Originally posted by NSXTC:
You guys are both right about the efficiency of the two basic different types of SC designs. However, here is the piece of the puzzle that is missing from this discussion which I think will resolve the paradox of why one SC system makes more power than the other. The CT SC is indeed a twin-screw type blower, which is in general more efficient than a centrifugal SC.

The rub, however is this: the particular Lysholm roots-type unit that CT uses just happens to reach it’s max efficiency at around 8.5 to 9 PSI with the NSX motor. What starts to happen at this boost level, with this particular blower is that the heat buildup is so great as to really start to take away from your peak dyno numbers. What the CT SC was designed to do from the get-go was to produce low-end grunt, not just peak dyno numbers.

Are you sure about the "screw" type versus the "roots" type? I know that the M uses a "roots" type of blower. The difference is in the rotor design. The screw develops its boost in the supercharger itself as it compresses the air then feeds it to the intake manifold. The roots sweeps air into the manifold where it develops the boost in the manifold. The heat is generated in the roots from air trying to retrace itself back into the supercharger. Also, some roots have teflon ends where the rotors try to seal the unit against the casing. This rubbing causes heat. The screw type's tolerances and rotor design enables compression and stops air from retracing back without touching (or minimal touching if any). With the twist in the rotor, it is able to compress the air in the supercharger and then send it to the manifold. This is what makes the screw type different and more efficient. The centrifugal design is awesome if you can keep the speed of the compressor wheel within its efficiency window. Unlike a turbo where you can tune the speed of the compressor wheel independent of the engine speed, the centrifugal design supercharger is dependent on the RPMs your engine puts out--too slow.... the air bleeds backwards--too fast the air get into turbulence due to the sound barrier build-up on the compressor fins. That is why the centrifugal supercharger has a PEAK efficiency window. Also, that is why properly turned turbos favored by many. Whew!!! That was confusing!!! Not bad from a Behavioral Scientist!!!

Engineers/Techies, please chime in if I'm not accurate....

Regards,

------------------
Kenji Ligon
91 Red CTSC NSX

[This message has been edited by Attitude Adjuster (edited 04 January 2002).]

 

[NSXTC]

Brain fart on my part. It's a twin screw, not a roots, and I should know as I used to own one!

I finally just edited by original msg to end any more confusion. Lud could also be right about his comment about the shorter intake tract being a culprit as well, but the main issue in this case is the efficiency curves of both specific models of blowers, when bolted to an NSX motor, not the relative theoretical efficiency of a hypothetical twin-screw vs. a hypothetical centrifugal blower.

[This message has been edited by NSXTC (edited 04 January 2002).]

 

[David Allen]

Still haven't seen an explanation as to why Mark's kit produces ~40RWHP more on a 3.0L than my CTSC 3.2L system.

Mark? You there? Somebody?

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

 

[NSXTech]

Originally posted by David Allen:
Still haven't seen an explanation as to why Mark's kit produces ~40RWHP more on a 3.0L than my CTSC 3.2L system.

Mark? You there? Somebody?

Yes David, I am here, though I have not been for a few days. (remember- Fri, Sat, Sun, SanDiego shop. M-Thur, Phoenix Shop.)

I don't mean to sound harsh, but I don't understand what you don't understand. The two basic reasons for more hp are the Centrifugal blower, and the stock manifold.
Though I agree with *most* of what's been said here, the 'big deal' is that the Whipple Charger that CT uses is pretty close to the limit of its effeciency while the Novi 1000 is just getting warmed up (pun intended) When I was doing pulley experiments with the CT kit a year ago, I discovered rather quickly that you can't spin the Whipple must faster than it already is because it stops making power at a speed only slightly higher than the speed it spins in the CT application. The Paxton however has (at 5.5 psi) almost another 40 per cent more power / speed to go. (speed, as in pulley speed) The Novi 2000 which we are using in the three 12 psi kits we are currently building engines for, has even twice the power to go so we are very excited about that. The closer you get to the max design limits of most anything you use in performance building / tuning, the less effiecient you are, *generally* speaking.

More to come (BG)
Mark

 

[cojones]

Originally posted by Lud:
CT uses a cut-down version of the intake manifold. This is the primary reason power drops off towards the very top of the RPM range with the CT unit. The Basch unit keeps the stock manifold.

Has anyone tested the CT-SC unit with the OEM intake manifold?

 

[cojones]

Originally posted by NSXTech :
The Novi 2000 which we are using in the three 12 psi kits we are currently building engines for, has even twice the power to go so we are very excited about that.

Am told that His Boostness has these cars producing upwards of 450 rwhp with significant changes -- reinforced (decked) block, lower-compression pistons, larger injectors, etc.

What configuration / boost level would get us to a streetable, reliable 400 rwhp on a 3.0L BB-SC setup ??

[This message has been edited by cojones (edited 07 January 2002).]

 

[MAJOR STONER]

Mark,

Is there any way to make LESS power on demand? Remember that scene in the movie Mad Max, where he is chasing down the Night Rider? He pulls on a lever, a pulley moves into place and engages, and the "supercharger" kicks in. Is something like this possible? Can it be disengaged or can the boost pressure be regulated? Can it be done from the cockpit? I would like the car to run almost as stock for bad weather winter driving, and would love to turn up the boost in the warmer months.

 

[DanO]

Originally posted by MAJOR STONER:
Mark,

Is there any way to make LESS power on demand? Remember that scene in the movie Mad Max, where he is chasing down the Night Rider? He pulls on a lever, a pulley moves into place and engages, and the "supercharger" kicks in. Is something like this possible?

Much of the boost control system you describe is already in place where the lever in the cockpit (terminated at the gas pedal) is connected to a butterfly valve in the throttle body <g>. Seriously, are you talking about a clutch on the supercharge pulley? I’ve seen these before on some supercharged American cars.

DanO

 

[cojones]

Originally posted by David Allen:
OK, but how come my 3.2L CTSC NSX only produces ~350RWHP and Mark is getting upwards to ~385RWHP on 3.0L cars?

I believe this has been explained in other threads, in terms of a more efficient design (blower) across a more usable powerband range (intake manifold). Plus Mark's had the benefit of firsthand experience in installing and tuning both the GM and CT SC units.

As an aside, 380 RWHP puts the NSX ahead, grunt-wise, of the 360 Modena, BMW Z8 / M5, and even the Vette C5 Z06 if you assume 10% drivetrain losses. That's a tad over 422 crank hp -- great for the local bench-racing circuit.

Make mine red !!

[This message has been edited by cojones (edited 07 January 2002).]

 

[grippgoat]

Originally posted by MAJOR STONER:
Mark,

Is there any way to make LESS power on demand? Remember that scene in the movie Mad Max, where he is chasing down the Night Rider? He pulls on a lever, a pulley moves into place and engages, and the "supercharger" kicks in. Is something like this possible? Can it be disengaged or can the boost pressure be regulated? Can it be done from the cockpit? I would like the car to run almost as stock for bad weather winter driving, and would love to turn up the boost in the warmer months.

It's not exactly pulling a lever in the cockpit. However, with the Basch Boost kit, you can simply use the stock alternator belt, which does not drive the compressor.

I'm not sure what kind of performance hit you take vs. stock in that situation, though.

-Mike

 

[nsxtasy]

Make mine red !!

I thought you generally prefer your cars in colors other than red...

 

[nsxxtreme]

Originally posted by grippgoat:

It's not exactly pulling a lever in the cockpit. However, with the Basch Boost kit, you can simply use the stock alternator belt, which does not drive the compressor.

I'm not sure what kind of performance hit you take vs. stock in that situation, though.

-Mike

Usually supercharger kits come with a bypass valve. I haven't read a lot about the BB supercharger to see if it does. My guess is that it does have a bypass valve that runs off of the intake manifold vacuum. So it pretty much does what your talking about already. If you don't have your foot to the floor there is little to no boost. Once you put your foot into it the bypass valve closes and you have boost. So you are the lever, you decide when you want boost. The thing that I like about supercharged cars is that they feel stock, just a larger motor. I have driven turbo cars before and don't care for the way they deliver the power.

 

[nsxxtreme]

Originally posted by cojones:
Has anyone tested the CT-SC unit with the OEM intake manifold?

I don't believe you can do this. Isn't the CT bolted to the stock manifold? The manifold is cut down to allow room for the supercharger. And the air exits the bottom of the supercharger into the manifold.

 

[Hrant]

Originally posted by David Allen:
Still haven't seen an explanation as to why Mark's kit produces ~40RWHP more on a 3.0L than my CTSC 3.2L system.

Mark? You there? Somebody?

Well, I am not an expert in these matters but I believe any response in layman's term should be sufficiantly succinct and clear to make its own sales ..........

Having said this, I understand the efficiency issue posted by Mark.

Correct me if I am wrong, but 40 hp aside, the basic difference between CT and BB is for what purpose you are intending the use of the SC. If I understand all the Dyno numbers and hype, CT offers more hp below a certain RPM (and was designed to offer more torque which it does when compared to the BB) while BB offers more hp at higher RPMs .......

So, if you believe that the NSX lacks torque (in comparison to what you should ask), then perhaps the CT is the better choice, if you want more hp at the higher RPMs where the VTEC is engaged (presumably for ....... technical types please fill in?) then BB is the choice.

Now again from a layman's perspective, one would assume that BB's power band will be less linear than that of CT, no? Pros and cons ....?

And if you have limited budget, that's a different story altogether all this becomes academic obviously ....

 

[Russ]

So... how close are the first production units to becoming available? What else stands between the hungry horde and their BBSCs?


------------------
Russ
'91 black/black

 

[grippgoat]

Usually supercharger kits come with a bypass valve. I haven't read a lot about the BB supercharger to see if it does. My guess is that it does have a bypass valve that runs off of the intake manifold vacuum. So it pretty much does what your talking about already. If you don't have your foot to the floor there is little to no boost. Once you put your foot into it the bypass valve closes and you have boost. So you are the lever, you decide when you want boost. The thing that I like about supercharged cars is that they feel stock, just a larger motor. I have driven turbo cars before and don't care for the way they deliver the power.

Well, the thing about the BB kit and other kits for other 8000rpm motors that use a centrifugal blower, is that they don't really make very much boost below, say, 4000rpm (I'd give a better guess if I were looking at a dyno chart or a boost gauge). So it doesn't really seem like you'd need a bypass valve. If you're just tooling around, shifting at 3000rpms and partial throttle, then you're not really going to see much boost. But once you dip into the higher RPMs, the compressor will really get going and you'll have a smile on your face.

Now, that analysis is not intended to answer the question of whether or not the BB kit does, in fact, have a compressor bypass valve. I don't know if it does. I just suspect that it doesn't really need one.

-Mike

 

[NSXTech]

Originally posted by Russ:
So... how close are the first production units to becoming available? What else stands between the hungry horde and their BBSCs?

Not much, I'm happy to report. I have changed so much from the original 5 beta testers that we are doing 5 more this month.
(car number 6 was finished Friday) We redesigned the main bracket to be more installer friendly, the crank and alternator pulleys are being upgraded to six groove instaed of "dumbing down" the Paxton unit from its original 6 to 5 groove,the SC end of the shaft support was re-designed because one cracked, and the fuel system has been changed though that "final" design is being selected from two different types still being tweaked, and a host of small changes.
Since the basic design is unchanged, we are not repeating the entire beta series, just enough to be 100 per cent sure of what we are doing. I expect cars in the first 20 wait
spots on the list to be done by end of February, but the wait list is pretty long.

As to boost levels and bypass valves, XTREME explains it best, IMO. Boost is a function of load, not RPM and your engine only has one way of undrstanding load demands and that is vaccum. (TPS informs the ecu of INTENDED load, not actual load) When the throttle goes to WOT, vac drops to zero and no longer holds the bypass open so the manilofd seals up and boost develops quickly. As the throttle closes and vac develops, the valve begins to open and boost escapes. In some cars, the escaping boost is rerouted back to the intake. In the BBSC, this air load is vented to atmoshere as it is very hot air and who wants a diet of HOT air at the t-body. (we tried to reroute this hot pressurized air to a devise which plays "La Cucaracha" between shifts on Dali's CC Special, but are still working out those bugs) So, though we do use this by-pass valve, its MAIN purpose is to avaoid compressor surge which is a condition that excists when you get a SuperCharger (any SC)
all worked up and then suddenly close the throttle. I drove my car with the very first (crude) BBSC without a bypass valve when I was TRYING to blow something up, and it was actually very drivable without a valve, but it took a little getting used to. I used throttle position alone to decide when I had boost and when I didn't and as Hrant speculates, it was not a bad thing, but in a very smooth retail application, it is a must.
Who wants to have to always think about driving? Automatic controls can be a good thing. Hrant is also correct that the BBSC may not be the SC of choice for everyone, but for the huge price difference, I personnaly can't see paying 4 grand more for the very small increase in low speed power. The way I drive my NSX, my SC makes more much sense. I always shift at 7700 to 7800 when I'm being 'aggresive' (my Doctor is trying new meds however), so the high end power is important to me.

YMMV, Mark Basch

 

[NSXY]

What is "WOT?"

------------------
NSXY
95 NSX-T, 5 sp, Red/Tan, Stock, except Dunlaptya SP9000s

 

[4g62bt2c30a]

Originally posted by NSXY:
What is "WOT?"

Wide open throttle

 

[ScienceofSpeed]

I've been known to play around with the throttle just to get that hard-on inspiring "whoooooooshhhhhhhhh!"

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http://www.NSXClassifieds.com - free NSX classifieds site!

 

[NSXY]

Vendor Jedi mind trick?

------------------
NSXY
95 NSX-T, 5 sp, Red/Tan, Stock, except Dunlaptya SP9000s

 

[SolidCitizen]

Originally posted by ScienceofSpeed:
I've been known to play around with the throttle just to get that hard-on inspiring "whoooooooshhhhhhhhh!"

Does it put out a loud sound even with only 5psi of boost? I've heard blow-off valves that make their presence known even under low boost, but then you end up hearing them all the time...even at light-throttle release.

Not that I care if there's any noise...ok maybe the riceboy in me likes it.

Jeff C

 

[nsxxtreme]

Since the bypass valve releases into the atmosphere are you still going to be able to get CARB approval? I thought I read somewhere you were going to try to get this.


[This message has been edited by nsxxtreme (edited 08 January 2002).]

 

[grippgoat]

Originally posted by nsxxtreme:
Since the bypass valve releases into the atmosphere are you still going to be able to get CARB approval? I thought I read somewhere you were going to try to get this.

The air from the compressor bypass is just like the air outside, except that it's compressed and it's warmer. It's not like a turbo wastegate, where you're talking about exhaust gasses.

-Mike

 

[nsxxtreme]

Originally posted by grippgoat:
The air from the compressor bypass is just like the air outside, except that it's compressed and it's warmer. It's not like a turbo wastegate, where you're talking about exhaust gasses.

-Mike

I know this, It's just that I know CARB can be pretty picky as well.