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Discussion Starter · #1 ·
I am writing a paper as part of graduate work for a mathematical modelling course at James Madison University. For the paper we are supposed to choose a data set of interest to us and perform statistical analysis and mathematical modelling to the data set and draw some conclusions.

I have chosen to look at stage times(average speeds) at North Amertican Rallies for the past 10 or so years. I have found good datasets for stage times which I can convert to average speeds easily.

I am going to generate a historical plot of average speeds for individual cars as well as groups/classes. I hope to use the trends in this data for a "control group" (groups that have not had restrictors required, or groups that have had constant restrictor size), and compare the trends of "control groups" to the trends of groups that have had restritors placed on them.

I have talked to a few engine builders to try to get data for the effects of a the restrictors on engine output, and I have got good response from a few. (however their data is for NA motors) I would like to find a few data sets either from engine builders dyno tests or competitors dyno results that will show the real world effects of restrictors on engine output.

Does anybody have or know where to get data on the effects of a restrictor on engine output? (I need numbers from actual tests or computer models not just word of mouth/assumptions)

I don't know if anyone has performed a similar study, but I would love to compare notes with someone who has.....If any one has data that may help me out please post or email me:

J.vimpty (at) verizon (dot) net

One big assumption of my modelling is that stage speeds are a function of engine output (engine output is at least a significant or limiting part of the function)

Thanks

Jeremy Wimpey
Trying to keep research paper writing somewhat exciting/interesting
 

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You might want to contact engineering colleges that have Formula SAE teams. The forumula SAE program requires 20mm restrictors (18 for methanol), if I remember correctly (and if they haven't changed the rules for the past few years).

During my time in school, we would start out with a 100bhp engine (600cc, dohc, 16v), and the restrictor would knock us down to about 70 hp. We never turbo'd, though. Might try contacting the Cornell FSAE team... they have tons of turbo/restrictor experience.

The only real problem that you may run into is that the FSAE rules mandated that the airflow order was throttlebody->restrictor->turbo->engine

turbos don't like vacuum.....
 

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Get ahold of a 'compressible fluid flow' textbook that deals with shock waves (normal, not oblique.)

I can't remember who wrote the one I have (at the moment) but it was a pretty decent description. Its basically a junior-level college text and is pretty thorough.

I hope you like ugly math.....

I lived with the 18mm restrictor for methanol (actually M-85) the entire time I was with Penn State FSAE and learned some very interesting things that may actually come in handy in 2005.

Matt
 

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>Get ahold of a 'compressible fluid flow' textbook that deals
>with shock waves (normal, not oblique.)

Also known as fluid dynamics (or gasdynamics, if you want to be more specific). Particularly look at the section on isentropic flow in a converging nozzle.

Note: Be certain that the worked examples are actually correct - the book I looked at recently had a calculation (units conversion) error in its worked example that threw me for a bit...

>I can't remember who wrote the one I have (at the moment)
>but it was a pretty decent description. Its basically a
>junior-level college text and is pretty thorough.
>
>I hope you like ugly math.....

Its not that ugly... (or, at least, it wasn't when I did it in university many years ago, and it wasn't too bad when I did the calculations again recently)

Adrian
 

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Can someone confirm the sequence of events related to stage notes and restrictors?

I think despite the restrictors decrease in HP, stage notes allows a much faster pace -- this may throw a wrench into the stage time data

I can't remember the exact years but I believe I ran LSPR in PGT:
1993: stage notes and restrictor
1992: stage notes no restrictor
1991: route book no restrictor

I remeber being considerable faster from the year with no notes to the year with notes and being miserable with the restrictor, but I am not sure how much time if any we lost.

good luck,
Mike
 

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Discussion Starter · #7 ·
Thanks for all the input so far. I have talked with an engineering student friend of mine and he is going to do some of the fluid dynamics calculations for me.

These calculations will represent all other things equal, and I would like to use real world data if possible, so that I can model what actually happened to engine output numbers with restrictors and restrictor changes.....as all other things likely did not remain constant.

If any teams or individuals have real world data they care to dig out and share it would be greatly appreciated. (I'll keep any data shared confidential, but would hope to use summarized/generalized results in my paper to draw conclusions and build models off of)

Thanks again.

Jeremy
 

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Jeremy--There is nothing really "equal" over that time span because of the dramatic changes in suspension, tires, differential technology and AWD systems.

IMO, those have bigger effects than a restrictor.

Now if you could somehow compare a bunch of smooth, straight segment
times...
 

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>Can someone confirm the sequence of events related to stage
>notes and restrictors?
>
>I think despite the restrictors decrease in HP, stage notes
>allows a much faster pace -- this may throw a wrench into
>the stage time data
>
>I can't remember the exact years but I believe I ran LSPR in
>PGT:
> 1993: stage notes and restrictor
> 1992: stage notes no restrictor
> 1991: route book no restrictor

I think you have the wrong decade ;-)

2001 No restrictors for PGT - no notes
2002 32mm for Pro/none for Club - notes
2003 32mm for all PGT - notes

Open had 40mm restrictors from at least 1997 (probably earlier).

It might be better to look at the Open transition from unrestricted to 40mm since there were less 'other' changes going on.

Adrian
 

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Discussion Starter · #10 ·
>Jeremy--There is nothing really "equal" over that time span
>because of the dramatic changes in suspension, tires,
>differential technology and AWD systems.

This is why I am using times/speeds of groups/classes that have not had restrictors as a "control group" of sorts....

I am trying to write a paper that examines the facts using mathematical modelling and statistical analysis techniques.
Using the data sets I have I can do this, I am looking for additional data that can help shed additional light on the subject. I have chosen to only focus on restrictors and their real world effects on stage times/speeds. (I have data to do this analysis)

If I can get factual "real world" data on restrictors effects on engine output for North American Rally cars, I can apply similar statistical analysis to these datasets as well. (I would like to get this data as it may be useful for further analysis of the above datasets) This data could help to explain trends in the above data or it may show that the above trends are not statistically significant.

I understand that not everything has remained "equal" as teams that were required to run restrictors hopefully remapped Fuel injection and changed engine components to optimize output with the restrictor. This is why I want real world data. Our car(PGT Toyota Celica) actually gained significant power after we installed a restrictor, as we finally got the cars piggyback computer programed and tuned properly. However looking at torque and power curves, the peak's distribution over RPM shifted to lower RPMs and trailed off more steeply at High RPMs.

I would ideally get data from a "large" sample of teams that show engine output before and after restrictors or changes in restrictor size. I don't know if any other teams have similar data available...but this is what I am looking for at this point.

Thanks again for the input....

Jeremy

PS I am not trying to make an arguement for or against restrictors, I am simply trying to apply some of forms of modelling and statistical analysis to a dataset that interests me.
 

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How long will you be on this project? I plan on doing some dyno tuning with and without my restrictor. I could send you my results. Current best dyno WHP without restrictor 338 corrected. 1988 Toyota Celica All Trac Turbo.
 

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Jeremy, I saw somebody on here not too long ago post some flow bench results of some restrictors....THis might be useful for Theoretical max HP calculations.

Check the Car construction posts for the last few months.

Of course, many of the cars running restrictor classes in the US are not optimized--then again, they probably wouldnt be optimized without restrictors either.
 

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>The parts I made and tested where as follows........
>
>
>40mm =470 cfm @ 28" H20
>34mm = 365 cfm @ 28" H20
>

And that's only a shade lower than the theoretical numbers I came up with using the converging nozzle equations.

Adrian
 
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