Header / Dyno question for HiTech John, SMSP, et al.....
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From: Snowwhitepillowformybigfathead
Header / Dyno question for HiTech John, SMSP, et al.....
So I've read some stuff that sounds like this: "I don't car about dyno numbers, only how fast the car (or motor) accelerates". Now most of us understand that these comments aren't simply about peak numbers, and we've seen a little discussion about it not being about area under the curve either. But at about that point the discussion goes no further toward explanation.
There are some references I'd like to frame my question with:
1) The current issue of Racecar Engineering has an article about traction control that provides background on the creation of useable power delivery. The fun part is the description of how Senna coped with a very uncivilized Honda turbo motor. But the gist of the part of the article relevant here is that we might want a nice flat torque curve for road racing applications with cars like ours because then we have an easier time controlling the cars transient cornering behavior in response to the throttle - making it easier to use the whole car.
2) I rode in a Jun'd out ITR last year on the track. It had a giant lump of mid-range and then flattened out all the way up to 9-something. I would have hated driving that car. My mostly stock car has very smooth power falling off a bit from 7500 up. Throttle control is entirely satisfactory - easy even.
3) Many years ago MXA did a shootout between a DG and a CH Elsie. Their conclusion was that the less ferocious bike (CH) was easier to ride and hence was generally faster around the course. All of my experiences pointed to the truth of this idea.
This brings me to the question. John - you like dyno's don't you. They are an indispensable tool. They allow quick runs, easier normalization of conditional data, etc. Is what you really mean when you say stuff like what I paraphrased in my intro that you are looking for a specific shape for the usable powerband in the interest of what I've described. Otherwise you've lost me and I'd like some additional description of what you're talking about. I know that your comments had more to do with time and distance rather than road course work, but the two ideas come together for most of your customers.
Scott, who always wants more info....except when it doesn't help anymore.....
There are some references I'd like to frame my question with:
1) The current issue of Racecar Engineering has an article about traction control that provides background on the creation of useable power delivery. The fun part is the description of how Senna coped with a very uncivilized Honda turbo motor. But the gist of the part of the article relevant here is that we might want a nice flat torque curve for road racing applications with cars like ours because then we have an easier time controlling the cars transient cornering behavior in response to the throttle - making it easier to use the whole car.
2) I rode in a Jun'd out ITR last year on the track. It had a giant lump of mid-range and then flattened out all the way up to 9-something. I would have hated driving that car. My mostly stock car has very smooth power falling off a bit from 7500 up. Throttle control is entirely satisfactory - easy even.
3) Many years ago MXA did a shootout between a DG and a CH Elsie. Their conclusion was that the less ferocious bike (CH) was easier to ride and hence was generally faster around the course. All of my experiences pointed to the truth of this idea.
This brings me to the question. John - you like dyno's don't you. They are an indispensable tool. They allow quick runs, easier normalization of conditional data, etc. Is what you really mean when you say stuff like what I paraphrased in my intro that you are looking for a specific shape for the usable powerband in the interest of what I've described. Otherwise you've lost me and I'd like some additional description of what you're talking about. I know that your comments had more to do with time and distance rather than road course work, but the two ideas come together for most of your customers.
Scott, who always wants more info....except when it doesn't help anymore.....
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From: Snowwhitepillowformybigfathead
Re: Header / Dyno question for HiTech John, SMSP, et al..... (RR98ITR)
I got this in e-mail, I hope the writer will forgive me for brining it back to the board (anonymously):
***********
Scott-
Basically, I agree with you regarding your comments
on the honda-tech board.
Most people only look at peak HP numbers, and
totally disregard the shape of the curve.
The more advanced/technically inclined people look at the torque
and the area under the curve for the useful part of
the RPM range they run -- for ITR's it usually
5700RPM's to 8400RPM's (VTEC).
Looking at the area under the curve (integrating the torque
curve) will show the work performed and hence the
acceleration possible. That should show how the engine
will respond in a given RPM range...almost.
I still think that there's more that a dyno can tell
us, but only up to a point.
Please feel free to tell me that I'm full-o-crap.
A dyno calculates the time needed to rotate a drum of
fixed mass and interia by some fraction of a revolution.
Based on time differential calculations, it can deduce
the linear acceleration in a given period, and hence the
torque needed to produce that acceleration. This is
correlated with the engine RPM at that particular point in time.
What a dyno does take into account is drivetrain/transmission
losses, lighter wheels and tires.
What a dyno does not take into account:
Air intake pressure and flow.
Exhaust vacuum (negative pressure relative to Atmosphere
behind the car) since the car is moving forward.
Transient response -- rate of change at which the acceleration
occurs between various RPM ranges -- think of this as
'adiabatic-like change' (slowly dropping sand pebbles on a scale and measuring) = Dyno
'transient / dynamic change' = Real world acceration.
A dyno plot from 5000 RPM to 5500 RPM steady state plot
taken as part of a larger 1000 - 8500 RPM plot is not the
same as what the engine would do if the driver had
shifted from 3rd gear at 6000 RPMs to 4th gear at 5000 RPMs
and hit the accelerator.
That is, the jerk and acceleration boundary conditions
at the 5000RPM mark is different.
The boundary condition on the dyno would be smooth,
with no jerk and acceleration numbers would be dictated
by an incremental difference from the previous value,
whereas, the real life situation has the engine decelerating
from a higher RPM, and then working to re-accelerate.
In the latter case, the engine acceleration is negative (during the
upshift), jerk would be in an inverted "U" shape with the peak
hitting the y-axis from below; then when the clutch was reengaged
in the new gear, the wheels would force the shock the drive train
and the acceleration of the engine would change from negative through
zero and positive to again start accelerating. The jerk at this time
would look like a "^", starting off at zero, and peaking during the sudden
change in acceleration, and slowly move back to zero as the
engine smoothly accelerated with a (hopefully) constant torque.
The ability to get high jerk value and better acceleration will get
the engine, and hence the car (via the transmission) moving faster.
So, maybe the degree of concavity of a dyno-plot would be
an interesting indicator.
How does an exhaust relates to this?
Perhaps it's a question of how the air escaping the chamber
reacts to the sudden tug of a spring (visualize exhaust system
as a mass attached to a spring, driven at a specific oscillation) --
whereas, the tug on the spring (air) on a dyno is more smooth.
A better exhaust would be one that is able to react to the
jerky acceleration and maintain proper air-damping and flow
in the critical moments surrounding the shift point.
******
1) Positive change in the slope of the torque curve gives what we call Jerk - the derivative of acceleration. This feels rewarding to street racers, isn't a bad thing for drag racers as long as traction isn't a problem, but I don't think road racers want very much of it.
2) I'm not sure that there is much that rotating an inertial drum can't tell us about a motor's transient response - that is in fact the heart of my question: tell me why a DynoJet is inferior to a rolling start timed run in the real world. Each has suboptimal variable control.
3) I don't think we should have to get too scientific in discussing this question....though neither should we accept any vague hand waving.
Scott, who thanks e-mail respondent, and looks forward to additional response from others.....?.......
***********
Scott-
Basically, I agree with you regarding your comments
on the honda-tech board.
Most people only look at peak HP numbers, and
totally disregard the shape of the curve.
The more advanced/technically inclined people look at the torque
and the area under the curve for the useful part of
the RPM range they run -- for ITR's it usually
5700RPM's to 8400RPM's (VTEC).
Looking at the area under the curve (integrating the torque
curve) will show the work performed and hence the
acceleration possible. That should show how the engine
will respond in a given RPM range...almost.
I still think that there's more that a dyno can tell
us, but only up to a point.
Please feel free to tell me that I'm full-o-crap.
A dyno calculates the time needed to rotate a drum of
fixed mass and interia by some fraction of a revolution.
Based on time differential calculations, it can deduce
the linear acceleration in a given period, and hence the
torque needed to produce that acceleration. This is
correlated with the engine RPM at that particular point in time.
What a dyno does take into account is drivetrain/transmission
losses, lighter wheels and tires.
What a dyno does not take into account:
Air intake pressure and flow.
Exhaust vacuum (negative pressure relative to Atmosphere
behind the car) since the car is moving forward.
Transient response -- rate of change at which the acceleration
occurs between various RPM ranges -- think of this as
'adiabatic-like change' (slowly dropping sand pebbles on a scale and measuring) = Dyno
'transient / dynamic change' = Real world acceration.
A dyno plot from 5000 RPM to 5500 RPM steady state plot
taken as part of a larger 1000 - 8500 RPM plot is not the
same as what the engine would do if the driver had
shifted from 3rd gear at 6000 RPMs to 4th gear at 5000 RPMs
and hit the accelerator.
That is, the jerk and acceleration boundary conditions
at the 5000RPM mark is different.
The boundary condition on the dyno would be smooth,
with no jerk and acceleration numbers would be dictated
by an incremental difference from the previous value,
whereas, the real life situation has the engine decelerating
from a higher RPM, and then working to re-accelerate.
In the latter case, the engine acceleration is negative (during the
upshift), jerk would be in an inverted "U" shape with the peak
hitting the y-axis from below; then when the clutch was reengaged
in the new gear, the wheels would force the shock the drive train
and the acceleration of the engine would change from negative through
zero and positive to again start accelerating. The jerk at this time
would look like a "^", starting off at zero, and peaking during the sudden
change in acceleration, and slowly move back to zero as the
engine smoothly accelerated with a (hopefully) constant torque.
The ability to get high jerk value and better acceleration will get
the engine, and hence the car (via the transmission) moving faster.
So, maybe the degree of concavity of a dyno-plot would be
an interesting indicator.
How does an exhaust relates to this?
Perhaps it's a question of how the air escaping the chamber
reacts to the sudden tug of a spring (visualize exhaust system
as a mass attached to a spring, driven at a specific oscillation) --
whereas, the tug on the spring (air) on a dyno is more smooth.
A better exhaust would be one that is able to react to the
jerky acceleration and maintain proper air-damping and flow
in the critical moments surrounding the shift point.
******
1) Positive change in the slope of the torque curve gives what we call Jerk - the derivative of acceleration. This feels rewarding to street racers, isn't a bad thing for drag racers as long as traction isn't a problem, but I don't think road racers want very much of it.
2) I'm not sure that there is much that rotating an inertial drum can't tell us about a motor's transient response - that is in fact the heart of my question: tell me why a DynoJet is inferior to a rolling start timed run in the real world. Each has suboptimal variable control.
3) I don't think we should have to get too scientific in discussing this question....though neither should we accept any vague hand waving.
Scott, who thanks e-mail respondent, and looks forward to additional response from others.....?.......
Trial User
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Posts: 1,345
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From: Toronto, On, Canada
Re: Header / Dyno question for HiTech John, SMSP, et al..... (RR98ITR)
from the Endyn BBS by John Grudynski of Hy Tech headers
Since we have been developing exhaust systems for race cars we have always been intrigued with the acceleration or transient time. And over the years the exhaust has become a very important part of that equation. Here are some real world testing that has been done on the Toyota Atlantic 4AG engine.These tests were perfromed by the engine builders and the teams running the cars. So it is unbiased. We have been working on the Toyota Atlantic program from its inception. We noticed that the exhaust systems didn't seem to make any real difference in how the engine ran on the dyno, we could change the rpm band but we couldn't make any big gains. Untill we tried the tri-y designed collector, up untill then we were using the 4 into 1 design.
What occurred was that the torque jumped up considerably, but it was out of the normal rpm range that the cars ran it. The normal range was between 6,000 to 9,500 rpm's. The big jump in torque occurred at 5,000 rpm and jumped about 40 lbs more. The engine builder said so what we don't run them there ever. And by the time the motor gets to 6,000 rpm's it was making about the same torque and HP as with the other exhaust pipes.
We finally convinced them to do a little track test the next time they went out. To everyones amazement they were 4 to 5 tenths of a second faster with the exhaust that I built them. Hallelujah! It only took them a few years to get it but they did and now the whole engine package has changed to help the transient response time. And the HP numbers don't mean much to them anymore. Now this was only one engine but we have found that this is the norm with most engines. And getting the most from them, meams working with building torque as soon as we can, with out totally giving up the HP. Thers is a fine line and testing is the only way to find it.
from Salami and response by Larry Widmer of Endyn
Question: Can you make timed runs on the Dynojet that have any importance? I noticed on some old dyno charts besides WHP there is a column marked time. It appears to measure the time it took to accellerate from one rpm to another(in this case from 4000 to 7700rpm). The run that had the lowest time was not the one with the highest horsepower. Would I be wasting my money if I tuned on the the Dynojet for the lowest acceleration time rather than peak WHP? Would this figure have any real world value?
Reply: it'd be worthwhile timing your runs, but you'd need to time a run in 2nd gear as well as one of 4th gear to obtain the best overall information, since the loads are higher in the upper gears....
First, all (successful) engine builders and race teams know all about "transient response", or "recovery time". The only standard dyno figure that (may) lead one to believe that the response will be "good" will typically be a torque "hump", prior to reaching the lower limit of the actual accaleration window where the engine's to operate.
Regarding what the books and professional engine building/dyno testing programs say: We know a lot of people that feel that those information sources are the best.
Those performance sources are all based on the accepted norm relative to engine data. In many cases one can't input anything to the programs, that isn't already "assumed". If the books and programs worked so very well, everyone would use them to design and build engines. If everyone used the programs, all the engines run in specific classes of competition would run the same. But, they don't. Perhaps the guys designing and building the winning engines are either not reading the books or not using the computer programs? Perhaps the subject matter that winners use is "different" from the information the rest of the "also-rans" are studying?....One last note: If you're winning races and the hp of your engines isn't up to what your competition has, should you really care?.....
When viewing conventional dyno numbers, the only thing that seems to be indicative would be a rise in the torque curve just prior to the lowest rpm encountered during the run. So, look for a hump in the torque curve in that area, and of course, the torque should also remain strong in the during the first third of the event.
The favorite question to prostock customers used to be.... I'll give you two torque values and two rpm points in which to place them for your motor. The torque readings are 900 ftlbs and 300 ftlbs. The rpm points are 7000 rpm and 9500 rpm. Tell me where you want the numbers. Everyone always picked 900 ftlbs for 9500 rpm,
I asked "what do you do at 9500 rpm? Answer "shift".
"Where are your revs after the shift and what kind of torque do you have at that rpm to pull back to the shift point?". This is called "opening eyes to reality".
When your car is in a dynamic state on the streets, the acceleration rate is a function of the real torque and response time of the engine....
On an engine dyno that's designed specifically to measure elapsed time, the engines equipped with development heads with the turbulators, were consistantly quicker than they were prior to the mods. This method of testing measures both the time it takes to pull a load from one rpm point to another, but it also measures the amount of time it takes for the engine to "recover" and begin accelerating from sudden load related rpm drops, such as those that occur on shifts.
Conventional dyno testing doesn't address these situations at all. We're looking at time, just as you'd look at time in the real world of racing.
Since we have been developing exhaust systems for race cars we have always been intrigued with the acceleration or transient time. And over the years the exhaust has become a very important part of that equation. Here are some real world testing that has been done on the Toyota Atlantic 4AG engine.These tests were perfromed by the engine builders and the teams running the cars. So it is unbiased. We have been working on the Toyota Atlantic program from its inception. We noticed that the exhaust systems didn't seem to make any real difference in how the engine ran on the dyno, we could change the rpm band but we couldn't make any big gains. Untill we tried the tri-y designed collector, up untill then we were using the 4 into 1 design.
What occurred was that the torque jumped up considerably, but it was out of the normal rpm range that the cars ran it. The normal range was between 6,000 to 9,500 rpm's. The big jump in torque occurred at 5,000 rpm and jumped about 40 lbs more. The engine builder said so what we don't run them there ever. And by the time the motor gets to 6,000 rpm's it was making about the same torque and HP as with the other exhaust pipes.
We finally convinced them to do a little track test the next time they went out. To everyones amazement they were 4 to 5 tenths of a second faster with the exhaust that I built them. Hallelujah! It only took them a few years to get it but they did and now the whole engine package has changed to help the transient response time. And the HP numbers don't mean much to them anymore. Now this was only one engine but we have found that this is the norm with most engines. And getting the most from them, meams working with building torque as soon as we can, with out totally giving up the HP. Thers is a fine line and testing is the only way to find it.
from Salami and response by Larry Widmer of Endyn
Question: Can you make timed runs on the Dynojet that have any importance? I noticed on some old dyno charts besides WHP there is a column marked time. It appears to measure the time it took to accellerate from one rpm to another(in this case from 4000 to 7700rpm). The run that had the lowest time was not the one with the highest horsepower. Would I be wasting my money if I tuned on the the Dynojet for the lowest acceleration time rather than peak WHP? Would this figure have any real world value?
Reply: it'd be worthwhile timing your runs, but you'd need to time a run in 2nd gear as well as one of 4th gear to obtain the best overall information, since the loads are higher in the upper gears....
First, all (successful) engine builders and race teams know all about "transient response", or "recovery time". The only standard dyno figure that (may) lead one to believe that the response will be "good" will typically be a torque "hump", prior to reaching the lower limit of the actual accaleration window where the engine's to operate.
Regarding what the books and professional engine building/dyno testing programs say: We know a lot of people that feel that those information sources are the best.
Those performance sources are all based on the accepted norm relative to engine data. In many cases one can't input anything to the programs, that isn't already "assumed". If the books and programs worked so very well, everyone would use them to design and build engines. If everyone used the programs, all the engines run in specific classes of competition would run the same. But, they don't. Perhaps the guys designing and building the winning engines are either not reading the books or not using the computer programs? Perhaps the subject matter that winners use is "different" from the information the rest of the "also-rans" are studying?....One last note: If you're winning races and the hp of your engines isn't up to what your competition has, should you really care?.....
When viewing conventional dyno numbers, the only thing that seems to be indicative would be a rise in the torque curve just prior to the lowest rpm encountered during the run. So, look for a hump in the torque curve in that area, and of course, the torque should also remain strong in the during the first third of the event.
The favorite question to prostock customers used to be.... I'll give you two torque values and two rpm points in which to place them for your motor. The torque readings are 900 ftlbs and 300 ftlbs. The rpm points are 7000 rpm and 9500 rpm. Tell me where you want the numbers. Everyone always picked 900 ftlbs for 9500 rpm,
I asked "what do you do at 9500 rpm? Answer "shift".
"Where are your revs after the shift and what kind of torque do you have at that rpm to pull back to the shift point?". This is called "opening eyes to reality".
When your car is in a dynamic state on the streets, the acceleration rate is a function of the real torque and response time of the engine....
On an engine dyno that's designed specifically to measure elapsed time, the engines equipped with development heads with the turbulators, were consistantly quicker than they were prior to the mods. This method of testing measures both the time it takes to pull a load from one rpm point to another, but it also measures the amount of time it takes for the engine to "recover" and begin accelerating from sudden load related rpm drops, such as those that occur on shifts.
Conventional dyno testing doesn't address these situations at all. We're looking at time, just as you'd look at time in the real world of racing.
sorry for the long quotes but it captures the flavour of the topic: dyno numbers are they a real reflection of performance?
obviously Larry and John believe that transient response time and load acceleration testing reflects reality over just whp.
This is why I believe the Honda Tech great header test should do acceleration time measurements in 2nd and 4th gears.Measure the time between say 4500 to 8100 rpm in those gears as well as reporting area under the curve and peak whp/torque.. John's headers accelerate the greatest at 5000-7000 rpm as you can see from his dyno below with his Hi-Y (hybrid long version 4-2-1).
cheers
[Modified by Michael Delaney, 8:39 PM 10/23/2001]
Trial User
Joined: Apr 2000
Posts: 1,345
Likes: 1
From: Toronto, On, Canada
Re: Header / Dyno question for HiTech John, SMSP, et al..... (RR98ITR)
BTW, I chatted with Dave Hsu at Skunk2 about dyno numbers and his view on them: Interestingly Dave chuckled when i mentioned that there are some who say that good dyno results aren't indicative of performance on the track and he then told me that every car he has had which dyno'd big numbers did well at the track. He's a believer in dyno numbers. At least one ex-record holding normally aspirated DRAG racing team (transient response is more important in road racing and slalom I believe) believes in dyno numbers.
As I said road racers and autocrossers may want to look at transient response and load acceleration testing more than drag racers.
cheers
As I said road racers and autocrossers may want to look at transient response and load acceleration testing more than drag racers.
cheers
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Honda-Tech Member
Joined: Mar 2001
Posts: 3,468
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From: Weed Country, Holland, Netherlands
Re: Header / Dyno question for HiTech John, SMSP, et al..... (Michael Delaney)
As I said road racers and autocrossers may want to look at transient response and load acceleration testing more than drag racers.
cheers
cheers
Honda-Tech Member
Joined: Oct 2000
Posts: 5,790
Likes: 1
From: NC, USA
Re: I have to add to it... (ImportReview)
AREA UNDER THE CURVE is what makes a car quick, NOT peak HP!
As always, RR98ITR, your posts are well stated and have true content.
Same goes for Michael D. too.
As always, RR98ITR, your posts are well stated and have true content.
Same goes for Michael D. too.
Rather OG
Joined: Apr 2001
Posts: 8,179
Likes: 0
From: Greensboro, NC
Re: I have to add to it... (vtecvoodoo)
well said...
...unless all you do is drag race. in that case, you don't know what the hell you're missing
DV- who is not incredibly drawn to drag racing
[Modified by Darth VadeR, 3:23 PM 10/24/2001]
...unless all you do is drag race. in that case, you don't know what the hell you're missing
DV- who is not incredibly drawn to drag racing
[Modified by Darth VadeR, 3:23 PM 10/24/2001]
Junior Member
Joined: Sep 2001
Posts: 226
Likes: 0
From: San Diego, CA
Re: Header / Dyno question for HiTech John, SMSP, et al..... (RR98ITR)
I have a question, everyone who has responded to this thread; do you guys own either an SMSP or HiTech exhaust manifold? If so, how heavily is your motor moded? Is it just a stock itr or si with basic bolt-ons? or are they stroked or high compression motors? I am trying to make the decision of buying from either company. Its true that they say you get what you pay for. SMSP newer design for a 2.0L motor is around $950 (correct?) and the Hitech retails @ $1,300?....do either of these companies offer a money back guarantee or any type of assurance that if you buy their product you will make the amount of HP they advertise? Just curious, thanks
Honda-Tech Member
Joined: Jan 2000
Posts: 5,013
Likes: 0
From: Moorestown, NJ, USA
Re: I have to add to it... (Darth VadeR)
i was wondering why i bought this
http://www.geocities.com/t-type3/1962mini.jpg
http://www.geocities.com/t-type3/1962mini2.jpg
try cut and pasting from here then
http://www.geocities.com/t-type3/1962mini.jpg
http://www.geocities.com/t-type3/1962mini2.jpg
try cut and pasting from here then
Rather OG
Joined: Apr 2001
Posts: 8,179
Likes: 0
From: Greensboro, NC
Re: I have to add to it... (Lip)
can anyone see the 2 photos i just posted?
Send 'em to me and I'll post them for ya. typeRjason@cs.com
Honda-Tech Member
Joined: Nov 2000
Posts: 11,967
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From: Charlotte
Re: I have to add to it... (Lip)
http://www.geocities.com/t-type3/1962mini.jpg http://www.geocities.com/t-type3/1962mini2.jpg
Take off http://
Copy and paste.
Looks a bit small for me.
Willis
Take off http://
Copy and paste.
Looks a bit small for me.
Willis
Member
Joined: Feb 2000
Posts: 3,887
Likes: 0
From: Philly, PA, USA
Re: Header / Dyno question for HiTech John, SMSP, et al..... (RR98ITR)
Scott, great post/questions as per usual. 
i have just one sidenote.....
from all the testing we're doing in my program, the general curve shape leads you to some conclusions, but they can only be verified with some statististics to tell you if your data really mean anything within a level of confidence.
also, just remember how a lot of dynos get their info... our claton engine dyno just reads off a strain gauge located at the water brake. everyone remembers what kind of hysterisis effects happens to strain gauges, engineers. now, i'm not very familiar with a dynojet, and how it obtains data, so, someone fill me in.
i've become so pessimistic anymore, it's rediculous. I've recently looked at in cylinder pressure data, intake runner manifold pressure data, for multiple configurations of header diameters on a restrictor plate motor, and i was amazed at how many hard it was to analyze the data based on statistics, and make an actual good decision about the data.
ok, i'm done rambling.
D
i have just one sidenote.....
from all the testing we're doing in my program, the general curve shape leads you to some conclusions, but they can only be verified with some statististics to tell you if your data really mean anything within a level of confidence.
also, just remember how a lot of dynos get their info... our claton engine dyno just reads off a strain gauge located at the water brake. everyone remembers what kind of hysterisis effects happens to strain gauges, engineers. now, i'm not very familiar with a dynojet, and how it obtains data, so, someone fill me in.
i've become so pessimistic anymore, it's rediculous. I've recently looked at in cylinder pressure data, intake runner manifold pressure data, for multiple configurations of header diameters on a restrictor plate motor, and i was amazed at how many hard it was to analyze the data based on statistics, and make an actual good decision about the data.
ok, i'm done rambling.
D
Honda-Tech Member
Joined: Jun 2000
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Re: Header / Dyno question for HiTech John, SMSP, et al..... (RR98ITR)
You bring up the main point of usable power. and how do we arrive at getting it. Different driving conditions such as drag verses road racing verses rally verses street use. All of them will want differnet characteristics. So how do we determine who wants what? Good question. The dyno is a valuable tool no doubt about it, but it is only one of many we use to develop products. The computer and the track are other tools we use as well. Remember different drivers within each catagory will also like there cars to perfrom differently. So there is a whole lot of combinations out there that will reach the same performance point throught different methods. As we see the development of these small 4 cylinder engines continue you will obviously see their performance get better and better. We have just begun to explore there potential. Who would have thought that an NA Honda could run 10.70's in the 1/4 mile. I beleive that it won't be to long before some one goes into the 9's.
So back to your dyno question. Its a tool we use but it isn't the whole picture. If we raced the dynos then we would pit dyno's against dyno's. But we don't so we have to come up with other things to measure the performance of each engine. Blanket statments like from Dave Shu my apply to what he does but not across the board. He is only dealing with one type of engine while we work with all types of them. And with the technology of onboard computers to monitor the car and drivers performance we can tell pretty easily how certian things work, and do they help or hurt the cars perfromance. Something the average guy doesn't have. If he did you would easily see half of the after market business fold in a minute. Mianly you could tell if those products hurt or help your cars perfromance. Or what combination of parts work the best for your particular driving style. Like Senna who could carry the car no matter what. He could adapt his style to fit the set up on his car. He was a talent like no other.
So how does the exhaust influence the cars acceleration. Another good question. To bad I don't have all the perfect answers I don't. But what I do know leads me in the right direction to develop exhaust systems that really help. Since we deal with stepped primary pipes and tri-y collectors we can influence the speed of the exhaust gases all the way through the exhaust. And use it to make more power. It is alot more complicated than just saying that but that is the jist of it. Being able to manipulate the gases to do what you want. When we get it close we notice the performance of the motors pick up. The we can hone in on a more specific design to enhance a particulr part of the power band. We can put it in the middle or the bottom or the top. But what we can't do is make it great at every rpm. The pipes would have to be active in their length and diameter to do that. They would have to be alive to be able to change that fast to accomodate what we would like to see. So since we can't do that we have to make the best of what we have. Compromise is the term we use when building an exhaust. It is a never ending formula that we can use to develop pipes. There are hundreds of different combinations that we can use and probably another hundred more we haven't thought of yet. As we continue to develop exhaust for all types of cars and racing series we get a picture we often see, and that is each engine likes what it likes and what works for one will not necessarly work for another. We treat each one as a new piece and start at the beginning and go through the development process to find out what it likes. One thing does hold true and that is we continue to learn all the time and find things that we thought we had a handle on we really don't. As the development changes in the years to come so will the exhaust and the great debate of which is better and who's does what and why. The end result will be, wider power bands and more usable power, and the exhaust will always continue to be a big part of that. Maybe in the future someone can expalin it all and fill the void with knowledge.
The last point is the car that accelrates the fastest is the fastest no matter how much power it makes.
So back to your dyno question. Its a tool we use but it isn't the whole picture. If we raced the dynos then we would pit dyno's against dyno's. But we don't so we have to come up with other things to measure the performance of each engine. Blanket statments like from Dave Shu my apply to what he does but not across the board. He is only dealing with one type of engine while we work with all types of them. And with the technology of onboard computers to monitor the car and drivers performance we can tell pretty easily how certian things work, and do they help or hurt the cars perfromance. Something the average guy doesn't have. If he did you would easily see half of the after market business fold in a minute. Mianly you could tell if those products hurt or help your cars perfromance. Or what combination of parts work the best for your particular driving style. Like Senna who could carry the car no matter what. He could adapt his style to fit the set up on his car. He was a talent like no other.
So how does the exhaust influence the cars acceleration. Another good question. To bad I don't have all the perfect answers I don't. But what I do know leads me in the right direction to develop exhaust systems that really help. Since we deal with stepped primary pipes and tri-y collectors we can influence the speed of the exhaust gases all the way through the exhaust. And use it to make more power. It is alot more complicated than just saying that but that is the jist of it. Being able to manipulate the gases to do what you want. When we get it close we notice the performance of the motors pick up. The we can hone in on a more specific design to enhance a particulr part of the power band. We can put it in the middle or the bottom or the top. But what we can't do is make it great at every rpm. The pipes would have to be active in their length and diameter to do that. They would have to be alive to be able to change that fast to accomodate what we would like to see. So since we can't do that we have to make the best of what we have. Compromise is the term we use when building an exhaust. It is a never ending formula that we can use to develop pipes. There are hundreds of different combinations that we can use and probably another hundred more we haven't thought of yet. As we continue to develop exhaust for all types of cars and racing series we get a picture we often see, and that is each engine likes what it likes and what works for one will not necessarly work for another. We treat each one as a new piece and start at the beginning and go through the development process to find out what it likes. One thing does hold true and that is we continue to learn all the time and find things that we thought we had a handle on we really don't. As the development changes in the years to come so will the exhaust and the great debate of which is better and who's does what and why. The end result will be, wider power bands and more usable power, and the exhaust will always continue to be a big part of that. Maybe in the future someone can expalin it all and fill the void with knowledge.
The last point is the car that accelrates the fastest is the fastest no matter how much power it makes.
Honda-Tech Member
Joined: Mar 2000
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From: Kelowna Canada
Re: Header / Dyno question for HiTech John, SMSP, et al..... (hitechex)
So in other words - timed acceleration testing, lap times, trap speed times etc are the best tool for your average Joe to tune their car (along with some basic dyno work) to what they feel is the optimum performance??
Trial User
Joined: Apr 2000
Posts: 1,345
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From: Toronto, On, Canada
Re: Header / Dyno question for HiTech John, SMSP, et al..... (SEFI8LOxCivic)
by SEFI8LOxCivic
Yea, but then again, look at whos header he (Dave Hsu of Skunk2) was running. LOL
Yea, but then again, look at whos header he (Dave Hsu of Skunk2) was running. LOL
I'm sure John can straighten out the facts or I can ask Dave to come on and comment himself.
As for whether I use a Hy Tech header? yes I do. Just got it last week from John. The plan is to run 12:1 compression with my Toda B's and a Kakimoto 70mm exhaust. I'd be ecstatic if the car runs in low 13's and gets me through Mosport on lapping days in the 1 min 38-39's on Yoke A008's (Kleinubing did Mosport in 1min 35-ish for the pole in the Realtime ITR and John Sherk ran 1 min 34-ish in the Grand Am JComp NSX).
cheers