LexCiting

Thanks Man! I actually may have another race. With a twin turbo Acura NSX! lol Today I tried to bait a CL500, but no go! Oh well!!!! That CL500 is one sweet car!

onefastjap

How does it feel to have first GS twin turbo in a world? I bet people PM you all the time asking for a ride. And the amazed look on people faces when you blow away their cars... The Twin Turbo NSX, where is it located. Someone as Supra Forums raced one and walked it up 160 mph. I try finding that post for you.

I want one now (GS) that I see what you have done with your car.

P.S. Is the NSX in Austin. If so than it puts down just under 500hp to the wheels.

LexCiting

Actually the NSX is in VA. He should be up to MD at SRT to get some tuning done at SRT, since they have a wideband dyno on site. He wants to run me at highway speeds. He said his car is putting something like 435 at the fly, but he has his gearing set up for highway speed.

JBrady

Congratulations on having the courage to spend a small fortune on a brand new system. SRT have defined themselves as competent and serious tuners so I understand your confidence in them. Bragging rights on your car are massive

However, I am very curious about the dyno. Generally (virtually always) a turbo car makes boost sooner and peaks sooner than a centrifugal supercharger. This shows up as more low end power/torque and a relatively flat torque curve... very similar to the SC curve??? I don't understand why your SC dyno has more low end power than your TT???

The torque curve is VERY pointed, again unusual. One possibility is the v-v-t-i is kicking in and actually hurting the power curve with too long a duration or too narrow a lobe center. I understand that some of the turbo Honda cars disable the variable valve timing for these reasons. This is due to the relatively high exhaust manifold pressure creating reversion during valve overlap. On your GS with the stock cats and Y-pipe this seems VERY likely an is a car SCREAMING for better flowing parts in these areas and possibly no valve timing changes.

miko400

Lee, that's enough HP for me.

retrodrive

Amazing. This is really impressive numbers. Congrats on your dedication and car!

JAC JZS

Very impressive, I look forward to seeing potential hp after the break-in period.

LexCiting

jbrady - Well, I thought that a SC would go into boost sooner than a turbo because it is always running, and turbos have a "lag" because it is pulling the exhaust out. If you look on the dyno graph, you can kinda see what I am talking about. The SC shows a gradual consistent rise in boost, while the turbo graph shows a little lag, then an instant spike in both HP/TQ. But I could be wrong. Anyone care to share in this? I wouldn't doubt that putting race cats on the car would smooth out that spike.

Lee

tomtnc

You are correct.

Typically, supercharged applications will build HP/TQ earlier in the powerband vs. a turbocharged application (everything else being equal) becuase the supercharger is crank driven vs. exhaust driven (interia lag) turbocharger.

LexCiting

The engine again

LexCiting

huge intercooler...

LexCiting

and the ultimate sleeper....

JBrady

Lee, it depends on the TYPE of SC. SRT used at least 2 different SC units, an ATI and a custom built unit. These are both centrifugal compressors (like a turbos compressor). I haven't seen and seriously doubt that the SC you had was a positive displacement type (roots, lysolm, vane). On a positive displacement supercharger boost starts right off idle and stays fairly flat to redline. On a centrifugal SC the boost generally starts around 2500rpm and builds to peak boost at redline. It builds somewhat linearly and is less than full anywhere between onset and redline.

Turbos are different and depending on how they are sized they can start making boost very low or fairly high. Most street applications see boost start at around 2000rpm reaching peak by 3000rpm. Peak boost is held too redline by the wastegate.

In comparing a typical turbo to centrifugal SC... the turbo starts making boost sooner, gets to full very quickly, and therefore has MORE low end and mid range and usually peak power than the same boost level SC.

Now, I don't know what the boost curve looks like for your car or what it looked like with the SC. It is just not what I have seen in most comparisions like this one.

LexCiting

I am confused? I thought a SC would always get into boost faster than a turbo, just from the fact that a SC is running because of the engine? Now I am not an expert at all on this, and am asking a question, not stating anything. That dyno with the SC shows basically the same linear climb as my SC setup, outside of it hitting a higher HP than I had. If you look at the beginning of the dyno (the red line), you see that on idle the SC is already in the beginning stages of boost, while the turbo is sitting there spooling up. Wouldn't it take longer for a turbo to wait on the exhaust to spool it, than a SC would to spool, since the SC is already turning from being chained to the engine belt? With a SC, the climb would be linear since the faster the engine RPMs, the faster the SC spools up, thus more linear power, while the turbo has to wait for the exhaust to be expelled in order to turn, and spool, before producing boost?

tomtnc

I had a friend with a 99 C5 that had originally (centrifugal) supercharged the car but later removed to turbocharge / intercool . Both applications were on the stock internals. I saw both dyno plots at 7psi of boost. I wish I had those plots available to share with you all, but I don't. I can tell you in his application the supercharger built power quicker (not necessarily in magnitude). However, the turbocharged application began to make more power vs. supercharged around 3K rpm and increased the margin of gain all the way to 6200 rpm.

I know for a fact there are a lot of supercharged and turbocharged LS1 applications running around - do some research on the web and I am sure you will find more examples to draw a conclusion for yourself.