Turbo v Supercharge
09-16-2009, 05:38 PM
#51
An ideal setup would have zero manifold pressure. "Boost" is resistance to flow.
Look at the actual mass airflow on an S/C vs. a turbo after the torque peak. They are the same (or better for the turbo, depending on the efficiency in that range).
All the blower is doing at that point is dragging on the motor and making heat.
The higher manifold pressure is just an indication of the S/C working against the motor, not with it.
09-16-2009, 06:56 PM
#52
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Once again - demonstrating the fundamental misunderstanding of boost.
An ideal setup would have zero manifold pressure. "Boost" is resistance to flow.
Look at the actual mass airflow on an S/C vs. a turbo after the torque peak. They are the same (or better for the turbo, depending on the efficiency in that range).
All the blower is doing at that point is dragging on the motor and making heat.
The higher manifold pressure is just an indication of the S/C working against the motor, not with it.
An ideal setup would have zero manifold pressure. "Boost" is resistance to flow.
Look at the actual mass airflow on an S/C vs. a turbo after the torque peak. They are the same (or better for the turbo, depending on the efficiency in that range).
All the blower is doing at that point is dragging on the motor and making heat.
The higher manifold pressure is just an indication of the S/C working against the motor, not with it.
09-17-2009, 12:40 AM
#56
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I've got a clearer idea now. I found this to be a useful explanation for the non-technically minded when googling around:
http://www.modified.com/editors/tech...ble/index.html
It's interesting to go back to the chart with that in mind. Thanks for the tip...
09-17-2009, 12:46 AM
#57
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Really, it depends what you want. I'm still improving my track driving skills. I don't need some monster that will intimidate me and curtail that improvement. I'd prefer to match the car to where I'm at skills-wise rather than simply go for max grunt, etc.
I salute your enthusiasm though. Great that there's people out there milking these cars for all they're worth. ..
09-17-2009, 12:49 AM
#58
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So why does the SC curve keep heading north with revs then while the turbo curve starts to drop?
I'm not being argumentative. I'm genuinely interested and might even learn something!
Against a flame attack...
I'm not being argumentative. I'm genuinely interested and might even learn something!
Against a flame attack...
09-17-2009, 01:04 AM
#59
Hahaha, I'll take your word for it.
Really, it depends what you want. I'm still improving my track driving skills. I don't need some monster that will intimidate me and curtail that improvement. I'd prefer to match the car to where I'm at skills-wise rather than simply go for max grunt, etc.
I salute your enthusiasm though. Great that there's people out there milking these cars for all they're worth. ..
Really, it depends what you want. I'm still improving my track driving skills. I don't need some monster that will intimidate me and curtail that improvement. I'd prefer to match the car to where I'm at skills-wise rather than simply go for max grunt, etc.
I salute your enthusiasm though. Great that there's people out there milking these cars for all they're worth. ..
I see where you are coming from and I gotta say the Hymee fits in well with what you want to achieve .
09-18-2009, 04:28 PM
#60
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Can you repost it please?
The questions about all of this that I would like to see answered are;
How much power is best for road use?
The car is pretty well balanced now once moving but getting off the line is a bit of a weakness.
Is 20-30% more power the reasonable target?
If so what is a ballpark figure for this?
In my opinion it is the handling of the car that provides the endless struggle against driving it illegally not the power.
Would this change with more power?
09-18-2009, 05:00 PM
#61
That chart is gone.
Can you repost it please?
The questions about all of this that I would like to see answered are;
How much power is best for road use?
The car is pretty well balanced now once moving but getting off the line is a bit of a weakness.
Is 20-30% more power the reasonable target?
If so what is a ballpark figure for this?
In my opinion it is the handling of the car that provides the endless struggle against driving it illegally not the power.
Would this change with more power?
Can you repost it please?
The questions about all of this that I would like to see answered are;
How much power is best for road use?
The car is pretty well balanced now once moving but getting off the line is a bit of a weakness.
Is 20-30% more power the reasonable target?
If so what is a ballpark figure for this?
In my opinion it is the handling of the car that provides the endless struggle against driving it illegally not the power.
Would this change with more power?
as std the car is hard to launch due to lack of torque and it bogging down. too much power and you sit and spin. this can be annoying.
I'm still on a std suspension. it can take the added torque but when you step on the throttle the rear suspension gets a torque wobble. I want suspension mods to tie it down. with a turbo and more torque it would be nearly essential to re-work the suspension.
more power the more illegal you will get. I still feel the car is very nice to drive NA. keeping the revs, flow up around the streets is enjoyable. with the SC I tend to squirt the throttle between corners. if I kept the throttle down the same way I drive NA the speeds are silly on the street.
09-18-2009, 05:02 PM
#62
here you go . I recently updated it so the link was destroyed .
For road use you want the broadest possible spread of power and torque - see the pink line .
As to how much total power is best - the is no right answer for that without knowing what you are trying to achieve .
09-18-2009, 06:00 PM
#63
With the turbo there are several factors that come into play -some of which are :
*As rpms climb - backpressure at the turbo climbs . Eventually this can rise to such a level that the wastegate gets forced open causing a dropoff in boost/flow.
Most of the dynos from members here show this characteristic.
*Intercooler size , exhaust size etc can also cause power to level out but not necessarily drop away much.
*Assuming you overcome the issues above and are able to hold the same boost all the way to the redline , at a certain point the volumetric efficiency of the motor decreases and airflow will stop increasing . You are now fighting against the flow capabilities of the ports. This will cause power to flatten out - and perhaps drop somewhat as well ,as frictional losses increase.
*Of course the maximun flow capability of the turbo has an effect as well - if you have reached this point early in the power curve then there is nothing you can do to increase flow so power drops away due to increasing frictional losses .
So the short answer is : wastegate/boost control issues are the main cause of the dropoffs we see on this site .
Last edited by Brettus; 09-18-2009 at 06:15 PM.
09-18-2009, 06:19 PM
#64
Your chart is not useful to support your assertion because it shows power.
Area under the curve only applies to torque.
Because those charts are power and are normalized to RPM, the time component of power distorts the area under the curve.
BTW - The SC continues to climb until it finally makes it to where the turbo was many RPM earlier.
Area under the curve only applies to torque.
Because those charts are power and are normalized to RPM, the time component of power distorts the area under the curve.
BTW - The SC continues to climb until it finally makes it to where the turbo was many RPM earlier.
09-18-2009, 06:38 PM
#66
Nope. Not at all.
A peaky, high-horsepower kit will produce more area under the curve than a torquey, low-horsepower kit in a HP comparison, which this is.
Your chart shows some things as comparable that are totally incomparable, were we looking at the torque curve and the area thereunder.
A peaky, high-horsepower kit will produce more area under the curve than a torquey, low-horsepower kit in a HP comparison, which this is.
Your chart shows some things as comparable that are totally incomparable, were we looking at the torque curve and the area thereunder.
09-18-2009, 06:44 PM
#67
Nope. Not at all.
A peaky, high-horsepower kit will produce more area under the curve than a torquey, low-horsepower kit in a HP comparison, which this is.
Your chart shows some things as comparable that are totally incomparable, were we looking at the torque curve and the area thereunder.
A peaky, high-horsepower kit will produce more area under the curve than a torquey, low-horsepower kit in a HP comparison, which this is.
Your chart shows some things as comparable that are totally incomparable, were we looking at the torque curve and the area thereunder.
I also find it hard to believe that you , with all your knowledge and experience , can't look at a whp chart and see what the deal is without the need for a torque chart .
Last edited by Brettus; 09-18-2009 at 06:48 PM.
09-18-2009, 07:40 PM
#68
I see your point and agree that a torque curve is a better way to look at overall performance . However , if I just posted a torque curve 99% of the people that looked at it would be saying WTF - where is the hp chart ?
I also find it hard to believe that you , with all your knowledge and experience , can't look at a whp chart and see what the deal is without the need for a torque chart .
I also find it hard to believe that you , with all your knowledge and experience , can't look at a whp chart and see what the deal is without the need for a torque chart .
This is to educate the unwashed masses and it isn't doing the trick.
I spend all this time trying to get people to understand flow and torque and then a thread like this one comes along and sets us right back in the stone age.
09-20-2009, 05:46 PM
#71
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Well, as one of the poor benighted masses (but clean, thank you very much!), I've learnt something. Thanks for taking the trouble to explain a few things.
Brettus, why not post a torque chart underneath the HP chart?
Now excuse me, I've got to hunt some mammoth and then find a woman to club...
Brettus, why not post a torque chart underneath the HP chart?
Now excuse me, I've got to hunt some mammoth and then find a woman to club...
Last edited by Revolver; 09-20-2009 at 05:54 PM.
09-20-2009, 06:13 PM
#73
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09-20-2009, 11:16 PM
#74
Hmmmmmm.........
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Once again - demonstrating the fundamental misunderstanding of boost.
An ideal setup would have zero manifold pressure. "Boost" is resistance to flow.
Look at the actual mass airflow on an S/C vs. a turbo after the torque peak. They are the same (or better for the turbo, depending on the efficiency in that range).
All the blower is doing at that point is dragging on the motor and making heat.
The higher manifold pressure is just an indication of the S/C working against the motor, not with it.
An ideal setup would have zero manifold pressure. "Boost" is resistance to flow.
Look at the actual mass airflow on an S/C vs. a turbo after the torque peak. They are the same (or better for the turbo, depending on the efficiency in that range).
All the blower is doing at that point is dragging on the motor and making heat.
The higher manifold pressure is just an indication of the S/C working against the motor, not with it.
Damn it would be nice to have a simple way to log MAF and MAP simultaneously.