That seems high based on the 550 whp no? even if you assume a 20% loss in the drive train you wouldn't get that high. Either way the car must be a beast. I'd love a ride in an NSX like that.
My 2.9L Whipple SC
- Thread starter ken sampson
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That seems high based on the 550 whp no? even if you assume a 20% loss in the drive train you wouldn't get that high. Either way the car must be a beast. I'd love a ride in an NSX like that.
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The way I have this set up is one boost level at any RPM. With the three way rocker switch I have the following
Position one is 2 PSI from 3000 rpm to 8000 rpm
Position two is 10 to 12 PSI from 3500 rpm to 8000 rpm
Position three is 16 PSI from 3800 rpm to 7600 rpm
This can be changed if needed. Say I want 19PSI on race fuel for the track:smile:
Ken, did you buy that SC as a kit or fabricate it up?
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I fabricated the intake. The SC it's self sells from whipple for about 3K I think.
you can see more here. http://www.nsxprime.com/forums/showthread.php?t=90136
Ken -
Can you post a dyno plot showing hp and torque against RPM not wheel speed?
It would make a much clearer picture of how your system performs compared to other FI setups.
Thanks!
- Craig
Can you post a dyno plot showing hp and torque against RPM not wheel speed?
It would make a much clearer picture of how your system performs compared to other FI setups.
Thanks!
- Craig
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This is the only sheet I could get. My tuner said that once the wheels break loose we loose everthing else. I will be putting it back on the dyno once spring gets here. Or find a dyno with heat in there shop.
It looks like his peak HP is around 7000rpm based on a 4th gear pull and wheel speed. HP is a funtion of RPM and TQ (Power (hp) = Torque (ft-lb) * RPM / 5252 etc...). Based on that it looks like a peak of 410 RWTQ.
Wouldn't 410lbft of torque at 7000rpm be 546rwhp?
The attached graph I came up with is puzzling.
Assuming 7600rpm at 82mph, you should be able to divide 7600 by 82 giving 93 rpm per mph (it would have to be a linear relationship with 0 rpm = 0 mph, right?)
Then, with a little ruler work on the printed graph, the hp values per mph are able to be found (approximately).
Given that the pull starts at 52mph, that would mean the pull started at around 4800rpm.
What is very puzzling to me is both the 70 ftlb dip in torque and that the torque seems to climb so much as rpms increase, which is not typical for a screw type SC. Especially one that should have a constant boost pressure due to the controllable bypass valve.
It's also entirely possible that I screwed up the graph. Or that there is a LOT of wheel spin. Will be interesting to see the torque vs rpm plot in the spring.
Are you driving this beast around?? What's it like?
The attached graph I came up with is puzzling.
Assuming 7600rpm at 82mph, you should be able to divide 7600 by 82 giving 93 rpm per mph (it would have to be a linear relationship with 0 rpm = 0 mph, right?)
Then, with a little ruler work on the printed graph, the hp values per mph are able to be found (approximately).
Given that the pull starts at 52mph, that would mean the pull started at around 4800rpm.
What is very puzzling to me is both the 70 ftlb dip in torque and that the torque seems to climb so much as rpms increase, which is not typical for a screw type SC. Especially one that should have a constant boost pressure due to the controllable bypass valve.
It's also entirely possible that I screwed up the graph. Or that there is a LOT of wheel spin. Will be interesting to see the torque vs rpm plot in the spring.
Are you driving this beast around?? What's it like?
Ken. 511Hp is very respectable.:smile:
Something doesn't see right to me. I am NO expert.
I would not expect a dip in hp.
This may be due to the tune? Wheel slip?
I suspect something is not quite right.
I took a look at my dyno graph "attached". HP is nearly liner, at least monotonically increasing.
Torque falls off at the high revs as the slope of the hp starts to decrease.
I am very pleased with how my car turned out. :smile: As I am sure you are as well.
I need to thanks SOS for the great job they did with my car.
The boost comes on almost instantly and at low rpm's.
I don't have Boost pressure on the graph. I have a SPA boost gauge that records 13.5 psi.
I have a 95 OBDII car. Computer was pulling out timing and limited what we could get.
Again, I am still very pleased.:wink:
Something doesn't see right to me. I am NO expert.
I would not expect a dip in hp.
This may be due to the tune? Wheel slip?
I suspect something is not quite right.
I took a look at my dyno graph "attached". HP is nearly liner, at least monotonically increasing.
Torque falls off at the high revs as the slope of the hp starts to decrease.
I am very pleased with how my car turned out. :smile: As I am sure you are as well.
I need to thanks SOS for the great job they did with my car.
The boost comes on almost instantly and at low rpm's.
I don't have Boost pressure on the graph. I have a SPA boost gauge that records 13.5 psi.
I have a 95 OBDII car. Computer was pulling out timing and limited what we could get.
Again, I am still very pleased.:wink:
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I know the tuner said the wheels were spinning. The dyno is an in ground single wheel type and is in an area in his shop that is almost out side. I think now that I am tuned I should have someone else who has a two wheel type of dyno with a good heated space do a pull so I can have something better for my records. Or just wait until spring and have them do another pull so I won’t have all the wheel spinning. Ken
Shad's dyno bolts to the hub. Tire and wheels are not a factor.
I believe he uses a Dynapack chassis dynamometer.
Maybe you can find some one in your area that has this type?
Good luck.
Later,
Don
I believe he uses a Dynapack chassis dynamometer.
Maybe you can find some one in your area that has this type?
Good luck.
Later,
Don
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I was looking at your HP VS Torque graph and was wondering if he had taken the RPM to 8000 or even 8200 and if it continued making power as per the dyno would it have been 600RWHP at 8000 RPM's
Thanks
Thanks
Ken I found a dyno in Fairfax that I believe is much closer for both of us. Maybe a Spring run is in order?
Ken,
I have a freind with a dyno near Linthicum, MD. Let me know if you want to go.
Brandon
I have a freind with a dyno near Linthicum, MD. Let me know if you want to go.
Brandon
Well, a couple things to take into consideration first.
One, my graph uses both a limited number of data points (as well as ones that are eyeballed then derived off your hp vs speed graph), so extrapolating from it is not an exact science, to say the least.
Two, one point my graph tried to make is to highlight the unconventional torque curve of your motor, and since most screw type SC torque curves are similar, it implies that something is amiss, be it wheelspin or whatever.
Back to your question, in guesstimating what your HP might be, we only need to guess what your torque would be at 8000 or 8200 RPM, then multiply by the RPM and divide by 5252.
The weird thing that your torque curve seems to do is climb with revs, which is not what screw type SC's do. Nor would your boost controller regulated boost change that. The impact of your boost controller would be to make full boost sooner (if your SC is being overdriven and you are bleeding off pressure at full boost, which you are), and it would tend to prevent boost from falling off at the top end, which it sometimes does with screw type SC's.
If you take a look at Don's torque curve that he posted, I would say it's about the "perfect" example of typical torque curve. It comes up, flattens out, then drops off a little on the top end.
So the $100 question is, beyond 7600 RPM, does your torque climb, stay the same, or taper off?
My guess is that it stays the same or tapers off slightly. Granted it's not many data points, but it looks like your torque is flattening out based on your HP graph.
So, if your torque stays at 350 ft/lbs, then your hp would be 533hp at 8000RPM, and 546hp at 8200RPM. I would guess that your torque would begin to taper off by then, and that your peak hp would be somewhere between 7600 and 8000RPM, at around 530hp.
What I would really suggest is to end the suspense and go to a better dyno!
- C
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H.P. Works in VA did a great job on this setup. I have a three way switch Low boost 300RWHP, Med boost 400RWHP and High boost at 511 RWHP.
The low boost is fixed for when my wife gets in the car. The med and high boost have a boost controller that I can add or deducted boost. This way if I want only 475 at high boost I can just turn it down.
We stopped at 16PSI for now if I retune in the future with race fuel I may bump it up to 19PSI. Anyway he just about rebuilt most of my pulleys so my belt has no lift or slip.
I guess I should start looking for tires.
The low boost is fixed for when my wife gets in the car. The med and high boost have a boost controller that I can add or deducted boost. This way if I want only 475 at high boost I can just turn it down.
We stopped at 16PSI for now if I retune in the future with race fuel I may bump it up to 19PSI. Anyway he just about rebuilt most of my pulleys so my belt has no lift or slip.
I guess I should start looking for tires.
What tires are you running now? I've got R888s and they are great when the ground isn't frozen, but with the COLD lately traction is limited.
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Bridgestone Potenza SO-2 Pole Position
old tires from 2000 ?
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2003 They could be SO 3's
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I may take you up on that. The attached photos show the dyno I was using.
It's built into the ground and looks pretty old. He states it is right on the money. For anyone that’s interested this guy is going to sell SC boost controller kits. My low boost setting is 300RWHP and a flip of a switch it’s over 500RWHP that’s like hitting a 200HP shot of nitrous.
How does an SC boost controller work?
I think you just flip a switch and you get either 300WHP or 500WHP.
:biggrin::biggrin::biggrin:
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First you need to change your bottom pulley or the top but its better if you change the bottom on the crank. ATI makes a larger one built into there balancer.
This now gives you the high boost you need to tune. Then with H.P Work’s kit you set it up so that you have a low boost medium boost and high boost. You choose how much boost you want on the rocker switch at each level. Keep in mind you must have your car tuned for each level.
The other nice thing about this is I have a another adjustment for my medium boost so if the 400 at the wheels needs to be say 350 or 450 I only need to turn a knob. No additional tune is needed. I did call H.P. Works and Larry said he will have a few kits together soon he is waiting on parts. I hope this helps.
This now gives you the high boost you need to tune. Then with H.P Work’s kit you set it up so that you have a low boost medium boost and high boost. You choose how much boost you want on the rocker switch at each level. Keep in mind you must have your car tuned for each level.
The other nice thing about this is I have a another adjustment for my medium boost so if the 400 at the wheels needs to be say 350 or 450 I only need to turn a knob. No additional tune is needed. I did call H.P. Works and Larry said he will have a few kits together soon he is waiting on parts. I hope this helps.
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