SIR Discussion

[RussMcB]

Stan & Charles (you guys are CRB members, right?),

Can you share with us what CRB members are currently thinking about restricting speeds in FB, or if it's on their radar at all?

Knowing that might influence our plan or actions. For instance, if they are very aware and want to act fast, we may want to get our act togethjer ASAP.

Thanks.

Russ


PS. I tried to find a list of CRB members on SCCA.com. Pretty disappointing web site. Couldn't find anything even after looking at the Site Map. Search function never returned hits no matter what I entered.

[Rennie Clayton]

PS. I tried to find a list of CRB members on SCCA.com. Pretty disappointing web site. Couldn't find anything even after looking at the Site Map. Search function never returned hits no matter what I entered.

Contact information for the CRB can be found in the members area of scca.com, where one maintains their membership & enters the Runoffs online.

Directory > Boards & Committees > Club Racing Board


Hope that helps...


Cheers,
Rennie

[sidney]

How can you cheat an SIR?

It's a serious question (& not because I'd want to cheat).

All you need is a flap, valve, whatever, that is only active when the vehicle is moving. The bike guys do this now for meeting diferent performance and environmental requirements today. The inlet gets bigger when positive air pressure is applied to the flap. The the car is stationary, and the SIR is plugged, the flap is closed, the motor dies. If I were real clever, I'd incorporate the flap into the SIR so that it wouldn't be necessary to add extra ducting. With enough air pressure, you could just route the air around the SIR. That's the reason the F3 guys pull a vacuum. The flap or whatever would pop open and the vacuum test would fail. It's more difficult to police, but also a more robust procedure.

[rickspencer]

This may be a stupid question but why not use exhaust restriction?? Make a plate for each engine type and year. As power goes up make the hole smaller..... In tech the restrictor is checked and also the 2 exhaust gaskets are checked for leaks no easy way to hide it. burned out gasket = DQ....

[Lee Stohr]

Can't we start the day with a smile

[RussMcB]

[FONT=Arial]High performance at a low cost? In 1961 Harry Morrow wrote a book
about Formula Junior, then the equivalent of F1000 today.[/FONT]
[FONT=Arial]Nearly 60 manufacturers were involved, from England, Italy,
Germany and the US. The cars cost about $5000 to start. [/FONT]
[FONT=Arial]Today, that would be in the $30,000 range. Except they didn't
have data systems and 3 way shocks back then, otherwise the costs were very
similar.[/FONT]
[FONT=Arial]Mr Morrow points out that there has never been a "poor man's
racing, there is no poor man's racing, and there is never going to be a poor
man's racing".[/FONT]
[FONT=Arial]Still true today. Most men learn nothing from history, except that
they learn nothing from history [/FONT]

Is it a good thing that you need to be rich to race in a class like F1000? I guess it depends on your perspective. I'm addicted to fast open wheel formula cars, but my income vs. expenses won't allow me to spend tens of thousands of dollars on my hobby.

If, on the other hand, I had a business that sold expensive race cars, my perspective might be different.

[jerry freeman]

Restricting the exhaust I think would just do the same as restricting the fuel. The back pressure would overheat the motor and kill alot of good motors. Correct me if I'm wrong. I really think you have to restrict the inlet air.

To Lee Strohr,
I know racing is expensive and you don't care but don't try to kill this class in the first year.
It seems to me that anyone who publicly states they have no interest in building an F1000 car and is the first to have a car running and sold doesn't care about anything but his pocket book.

Jerry

[Daryl DeArman]

Under the current rules I can virtually assure you this will happen:

2007 ARRC - 2005/6 and 2007 GSXRs are the engines of choice, racing is close and everyone is happy

2008 Season - Factories market motor transplant kits (@$5000?). The serious racers show up with ZX10 power and whip up. 2006/7 GSXR Motors now sell for $1000 each, and newer ZX10s are in very high demand. "New" motors are impossible to find now that there are more than 10 active F1000 cars, and everyone wants a spare. F1000 founders are bummed out and wax poetic about the good old days when you could be competitive with a 2 year old eBay motor.

2009 Season - Honda updates the CBR1000 to 200hp V4 power for 2009. F1000 makers market a Honda CBR1000RR update kit over the winter. The season shows that you can't win without the Honda. Honda powered cars sweep the Runoffs podium (at indy?). The Kawasakis are firesold off. Everyone is scrambling to get new 0 mile Hondas at $4000+ each. Everyone who is 'serious' wants at least two. Costs? ($5000 update kit plus $8000 in new motors and spares)

2010 Season on - Privateers like us are gone. Only very well funded drivers run in F1000 now. The cars are refitted with the newest/best motor every year at substantial update costs. There are rumors of a whole new generation of narrow chassis specifically built to take advantage of the narrower V4 motors for 2011.

Sorry to dig up a post from a couple pages back but I am just catching up....

I agree 100%....you didn't happen to race CDCRA cars in the early 90's did you? Or was it 250FE shifter karts?

[RussMcB]

Would it be possible to list the pros and cons of the SIR? I'm pretty ignorant about them, so this list might help me have a better understanding of the reasons for and against them in F1000.

Here are the ones that pop into my mind. They may not be accurate, or even totally baseless. Feel free to shoot holes in this list, and please do add your own.

Pros:
Closer equality among different manufacturers, years (and engine types?)
Caps performance to stay between FA & FC
Increased competitiveness of older, less expensive engines
Reduced costs associated with desires to upgrade engines to be competitive
Increased durability/reliability?

Cons:
Extra cost ($350+?)
Fabrication to mount
Easy to cheat (some say)
Expensive to optimize
Restricts max RPM only (not torque, mid range)
Some engine designs' performance hurt more than others

[sidney]

Hey Russ,

I think you are on track here:

Some thoughts from my perspective.

It is only easy to cheat if the rules allow you to do it. If the rules are crafted correctly, it makes it a lot harder, I hate to say never, to cheat the SIR. We have lots of smart guys in the organization, just make sure the rule makes it too big a PITA to work around.

What is the development cost? There is already a proven manufacturer capable of providing the SIR. This seems like an easy way to ensure nobody is using a flexible membrane, oversized, or whatever type of customized SIR. I'm not opposed to saying this is the one spec part on my entire car. Only if it is the ONLY one.

A one-time expense of $350 seems a small price to pay for not having to upgrade my motor every year. As the power grows, the reliability should be better. The ZTECs have shown long life if you are not living on the ragged edge.

Restrict fuel -- Bad for engine
Restrict exhaust -- Bad for engine
Restrict air -- Bad, but not as bad as the other two?

[RussMcB]

Here's where I got that price:

http://www.raetech.com/Restrictors/Restrictors.php

More info here:

http://www.raetech.com/Restrictors/R...r_Function.php

[VehDyn]

I thought that from the past threads, adding the SIR would reduce the performance more than originally thought and the cost isnt for the part, its for the engine development to regain a little bit of the zapped power.

Ken

[Billy Wight]

Ok, I'll chime in here... During my FSAE time I did a project optimizing our inlet restrictor and spent a LOT of time in front of the computer, NC lathe, flowbench, and dyno. Throughout the project I tested (CFD, flowbench, and dyno) multiple different restrictor profiles, materials (for heat transfer reasons), and configurations. Here's my pros/cons list:

Pro's: (essentially repeating Russ on 1-4)
1) Closer equality among different manufacturers, years
2) Caps performance to stay between FA & FC
3) Increased competitiveness of older, less expensive engines
4) Reduced costs associated with engine upgrades
5) Lowered performance at high RPM's means fewer blown engines due to high RPM issues.


Con's:
1) Not easy to cheat, but possible (but that applies to everything really)
2) We would need to allow either programmable ECU's to fix the engine issues at RPM's higher than the choke point or some sort of rev limiter. Using the stock map at these higher RPM's with the SIR could lead to issues.
3) A programmable ECU + dyno time can be expensive, though it could be just a one time fee as well.

I don't feel that the cost of the restrictor is much of an issue as it is a one time fee. It also shouldn't be a spec part either. Anyone can make their own with a basic lathe (well anyone with that capability at least) that will be within a 10% flow rate of the best available profile. (Anyone with an NC lathe can make an optimum profile) This will allow for someone to make their own if they desire, or to come up with a quick fix in a pinch.

There won't be huge development costs for the restrictor design either as there are really only a few important parameters that if followed will get you to within 2% efficient of the maximum theoretical flow. I can post my results from all the testing I have done as to the optimum profile/material so people don't have to spend a lot of time and money figuring that out. The profile shown at http://www.raetech.com/Restrictors/Restrictors.php is close, but not the optimum.

The cost of making a proper airbox that integrates with the restrictor shouldn't be too huge ($500?). The ECU and dyno time could be big - $2500 for a good ECU, $500/hr dyno time with a good tuner (~3 hours), and the time to rewire the new ECU. The restrictor itself could cost between $0 (making your own) and whatever a machine shop would charge for a one-off piece (~$500). But the thing is, once you spend this money, you don't have to buy the latest and greatest engine every year and make it fit in your car ($$$$).

Throughout this thread I never saw any real reasons why not to impliment a restrictor other than "trust me we don't want to go there" which doesn't seem like a good reason to me. Aside from the initial cost issues listed above, I don't know of any reasons why not to do this.

[RussMcB]

Thanks, Billy. One of the main reasons I asked for the pros and cons was to get more info about, "Trust me, You don't want to go there." :-).

thought that from the past threads, adding the SIR would reduce the performance more than originally thought and the cost isnt for the part, its for the engine development to regain a little bit of the zapped powerquote]Ken, good to see you still in F1000 Land. :-).

I think SIR's can be made in any size and therefore restricting too much is easily corrected with a bigger hole. I'm sure that a lot of testing would be done before a required SIR size was determined, in an effort to cap it at 180 HP or whatever.

And to your second point, yes, there would surely be people who will choose to spend a lot on development to minimize the penalty of the restrictor. It would be interesting to hear how much might be gained. 1-3 HP? (uneducated guess)

[RussMcB]

We would need to allow either programmable ECU's to fix the engine issues at RPM's higher than the choke point or some sort of rev limiter. Using the stock map at these higher RPM's with the SIR could lead to issues.

Is it a mixture issue? If so, could a Power Commander or piggy back computer address it?

What bad might happen if the SIR was used without fixing engine issues at RPM's higher than the choke point?

[Billy Wight]

I'm not exactly sure, but I would assume that the mixture would go very rich. I'm really not farmiliar with the power commander, but I think the lack of available air would be out of its tuning tolerance (just speculating here). We never tried this, we always just used a properly tuned map (with an Electromotive Tec 3R ECU). Maybe George or someone with more experience in this area could fill us in.

[Charles Warner]

Stan & Charles (you guys are CRB members, right?),

Russ,

To clarify, I am not and never have been a CRB member. I was a member of the FSRAC for several years. I have since resigned that post due to other commitments.

Ergo, I have no dog in this fight.

[sidney]

I'm not exactly sure, but I would assume that the mixture would go very rich. I'm really not farmiliar with the power commander, but I think the lack of available air would be out of its tuning tolerance (just speculating here). We never tried this, we always just used a properly tuned map (with an Electromotive Tec 3R ECU). Maybe George or someone with more experience in this area could fill us in.

I see the ECU as a major price tag item. Currently they are illegal in FB, and I'd like to see it stay that way. You can buy ECUs for upwards of $8k for supersport bikes, and the DSR guys are already looking at spending this kind of cash. I too am hopeful that Mr. Dean or other experts can fill in some holes to help us understand how to add the SIR with minimal impact on the TIC (total installed cost).

The only reason I specified the SIR to be a stock part was to make cheating around the SIR more difficult. If they are all coming from one supplier, then you could theoretically throw them in a hat pull out the one you will run for the weekend from the pool. Kinda like what they do with restrictor plates in CrashCar.

[Billy Wight]

It would be very difficult to cheat the actual SIR. A simple diameter check can be preformed with a go/no-go type gauge to ensure compliance. Flexible membranes would be rather easy to catch. Throughout my FSAE days there were many discussions of how we could cheat the SIR (never implimented or tested, just fun talk over a few beers). Here is the jist of it:

1) Woven composite structure with a flexible matrix. Installation such that the restrictor bolted up axially and upon tightening the bolts the SIR would compress and expand the centre hole (think chinese finger trap). This would be easy to detect in an F1000 application. (in FSAE they checked SIR compliance with it out of the car)

2) SIR made from Nitenol or similar material that changed shape in response to temperature change. This would be difficult to develop and VERY expensive to pull off.

3) Solenoid valve mounted on the airbox that opens at WOT or similar, disguised as a MAP or similar sensor. This would actually be relatively easy to do and not too easy to detect.

There are probably other methods, but they would mostly involve cheating with an air leak of some sort in the airbox and not with the actual SIR.

[RussMcB]

3) Solenoid valve mounted on the airbox that opens at WOT or similar, disguised as a MAP or similar sensor. This would actually be relatively easy to do and not too easy to detect.

There are probably other methods, but they would mostly involve cheating with an air leak of some sort in the airbox and not with the actual SIR.

I wonder how that is policed today in other SCCA classes.

Who uses an SIR now. Is it GTL? I wonder what their opinions are of it.

[Wren]

in my FSAE days we accidentally made a cheater SIR. During the welding up of the aluminum, there was a spot that was hard to get to that did not get welded up. The engine would still cut out if you covered the intake, but the hole was definitely there.

That car spent lots of time on the dyno before and after we welded that hole shut(we did weld it up before competition). That small hole was worth 5-6HP on a 600cc engine.

A go/no go gauge may not pick up an oval hole.

[Jon Jeffords]

Per their website, the latest Power Commander III ($340) has +/- 100% fuel flow adjustability, while the optional ignition module ($355) provides +/- 10 degrees of spark advance/retard from factory timing. Should be more than adaquate for dialing in an SIR.

http://66.132.187.150/powercommander...formation.aspx

Even without an SIR, I assume most FB's (excluding MikeB) will be using a Power Commander to dial in the air/fuel ratio for their specific air intake and exhaust components.

Mike, on the other hand, will adjust his air/fuel ratio through the use of antique widgets called "jets" and "needles." Heck, even them thar' Harley tractor motors are fuel injected with closed-loop O2 feedback!

[Stan Clayton]

Stan & Charles (you guys are CRB members, right?)

Yes, I am a member of the CRB.

Can you share with us what CRB members are currently thinking about restricting speeds in FB, or if it's on their radar at all?

Yes, the CRB and F/SRAC are following the discussions here with interest. We share the FB community's concerns about the potential for rapid cost escalation due to the "engine of the year" issue, as well as the safety implications of further increases in engine power in light weight tube-frame chassis.

It is too early to discuss specific courses of action (as none have been settled on), but I can tell you that there has been no serious discussion of imposing an SIR. We've tried them on the dyno briefly twice now with less than stellar results using stock ECUs, and I anticipate that whatever we may do in future, an SIR will not be part of the equation.

Stan

[George Dean]

Thank You Stan

George

[Purple Frog]

Stan,
You seem to be quickly dismissing ther SIR, even before the discussion has worked it's way through the web.

I'm not saying I'm a SIR supporter, but as a national scrutineer I see the benefits of an easy to test piece, that could be easily supplied by SCCA to the competitors for a fee, and even swapped on the grid. No teardowns in impound. And I think I can find leaks, etc. or at least make folks squirm. We have "lolipops" to test intakes on F2000 pro cars, and I can tell you it's easy to spot oval holes.

And, maybe some other folks are starting to squirm a bit about the possible motor escalation in FB that sort of started this thread a few weeks ago. Right, Russ?

Don't let the competitors build them. SCCA build them to a spec, and the competitors build an airbox to install the spec piece in. We found out about the competitors building their own IMSA fuel restrictors for overhead fuel rigs back in the late 80's.

Just stirring it up...

[martyb]

Stan,
You seem to be quickly dismissing ther SIR, even before the discussion has worked it's way through the web.

I'm not saying I'm a SIR supporter, but as a national scrutineer I see the benefits of an easy to test piece, that could be easily supplied by SCCA to the competitors for a fee, and even swapped on the grid. No teardowns in impound. And I think I can find leaks, etc. or at least make folks squirm. We have "lolipops" to test intakes on F2000 pro cars, and I can tell you it's easy to spot oval holes.

And, maybe some other folks are starting to squirm a bit about the possible motor escalation in FB that sort of started this thread a few weeks ago. Right, Russ?

Don't let the competitors build them. SCCA build them to a spec, and the competitors build an airbox to install the spec piece in. We found out about the competitors building their own IMSA fuel restrictors for overhead fuel rigs back in the late 80's.

Just stirring it up...

I'm not a fan of SIR's, but if we have to do them I think NASCAR does it right.

1. There is only one manufacturer, and all plates are serialized.

2. There is a specified thickness, hole diameter and edge treatment (definition of square edge instead of a radius, etc.)

3. You can not have any kind of air flow enhancing air horn before or after the restrictor itself.

4. And the best rule of all: At each event all of the restrictors are collected by the officials, checked for legality, then are re-issued to a different team. This completely removes any opportunity to fiddle with the restrictor back at the shop, because that restrictor will be given to one of your competitors at the next event!

The NASCAR SIR is required to be immediately under the carburetor. Not applicable for a motorcycle engine, but I think a standard flat flange could be defined for the SIR to bolt to, and it would be a bolt-together affair in the air box.

Just thinking out loud ....

Marty

[RussMcB]

I finally got some insight into why SIR's might not work for F1000. When tried last year by two separate engine builders, the stock ECU apparently had significant issues dealing with the SIR. Rather than reaching the expected 170 HP (same size SIR used for GTL successfully), the engines would only do about 140 HP. It was like they went into limp home mode.

I hope that's accurate & okay to share. It came from a fairly reliable source and well respected builders were involved.

[Charles Warner]

Stan,
You seem to be quickly dismissing ther SIR, even before the discussion has worked it's way through the web.

I can guarantee Stan (or anyone on the CRB/F/SRAC) is not quickly dismissing this issue. It was examined to within an inch of its life with empirical data for a considerable period of time. Just because it wasn't broadcast all over the inter-web doesn't mean it was not thoroughly considered.

[George Dean]

Good evening, I did some testing on my dyno last year playing with different opening sizes for possible answers for the question that was given me about a single air restrictor. The answer in a nut shell is that when the restrictor was used it created a high vacume situation in the intake tract. The MAP sensor saw the abnormal amount of vacume and told the ECU that there is a problem. The ECU then goes to what I call a safe mode which means that it richens the fuel mixture and retards the ignition timing a bit. This is why it will be difficult to use a stock ECU (that the rules say must be used) to get a SIR to work with the desired results. What I found was if the restriction was big enough to not cause the safe mode the engine didnt lose any power, Once I made it small enough to lose power it went in to safe mode. My tests were not scientific but thats what I found to be the result. I hope that answers some of your questions.


George

[R. Pare]

George:

Is there a place/way to install the SIR after the MAP sensor? If so, I would think that would fix that particular ECU compatability issue.

[formulasuper]

From what I have been reading above it sounds like the SIR must be placed between the throttle bodies/carbs & the cylinders. Since bike motors have these devices rubber sleeve mounted one per cylinder it would appear a SIR is out of the question by definition. It would take a minimum of one per cylinder, making most current FB engines requiring 4 SIRs. Also with the rubber sleeve mounting arrangement this doesn't look to be practical, IMO.

[RussMcB]

George:

Is there a place/way to install the SIR after the MAP sensor? If so, I would think that would fix that particular ECU compatability issue.

Or, rephrased, is there a way to install the MAP sensor before the SIR. I phrase it that way because the MAP sensor on my engine is part of the air box, and I assume the SIR is typically installed before the air box. It looks like the MAP sensor is a simple vacuum sensor easily mounted anywhere.

As an aside, I was reminded last night that several people would be extremely unhappy if they had to install a SINGLE Inlet Restrictor because they have, or plan to have, dual inlets. I can understand the concern, especially if someone puts a lot of effort or money into a custom engine cover or air box with dual scoops.

[Stan Clayton]

Russ, the GT guys using SIRs find that placing the MAP sensor ahead of the SIR or outside the inlet tract altogether results in wildly fluxuating a/f ratios, even with fully programmable racing ECUs. To keep the a/f ratio right the MAP sensor has to report the actual pressure the ports see, which in practice means it has to be in the airbox. Stan

[Brands]

I really hope all this SIR talk is just for fun! If F1000 is required to use an SIR I'll run my car in FS.

Ben

[RussMcB]

I really hope all this SIR talk is just for fun! If F1000 is required to use an SIR I'll run my car in FS.

Ben

<sarcasm> Oh, yea, we're having a blast discussing the SIR in F1000. </sarcasm>

Based on the conversations I've had in the past 24 hours, I'm personally confident that the SIR is not going to be used in F1000 anytime too soon. That's not to say it wont in the future, but it was made clear to me that the SIR research done thus far had very unsuccessful results and, if it is going to be reconsidered, it will take a serious effort to re-research. Personally, I am not worried about the CRB making any knee jerk reactions to resolve (perceived) problems.

The only two scenarios where I can imagine the CRB feeling strong pressure to take action in the next few months would be:
1) Concern over safety (too fast for tube frames)
2) A large push by competitors that rules changes are needed.

Personally, I don't think either of those scenarios is likely.

Just my opinion, of course.

[Billy Wight]

George-

Did you test with a SIR and a Power Commander setup? Just curious if this might solve the problem or not. What diameters of SIR were you using? Flate plate or nozzle?

It seems to me that if the ECU issues could be resolved (relatively cheaply) that the restrictor would be a good idea for this class. The ECU seems to be the only problem with this idea. Can you see anything else that would be an issue?



It is possible to get a reasonable estimate of horsepower cut-off point with the isentropic choked flow equation and an assumed volumetric efficiency (this works for a nozzle type SIR). This will give you a RPM value at which the SIR chokes. Compare this RPM value to the unrestricted dyno curve to get a reasonable estimate of the horsepower cut-off. This would get a descent starting point for sizing the SIR.

Some people want dual inlets. This could either be handled with 2 restrictors of each a smaller diameter that flow at a rate equivalent to a SIR also allowed for the single inlet guys.

[George Dean]

Mr. Wight, I didnt test with a powercommander as I said in my earlier post that my testing was not scientific. My goal of the test was to see what the ECU would do when the air started being restricted. I had a feeling of what would happen before I started testing and they were confirmed after. All I did was block off 1 air intake on the stock airbox and started closing off the other with cardboard with single hole in it. As i said I was looking for what the ECU would do. I dont think a powercommander with ignition box would mask this problem. I think the only way to make this perform properly would be a completely programable ECU that does not use a MAP sensor,. Oh wait we have to use sock ECU's
I dont know if anybody else did any restrictor testing, But if they have I would like to hear of their results. Hope this helps

I must get back to work now on non restricted engines

George

[carnut169]

There are other options besides an SIR.

We (owners, potential owners, scca, and vendors) all want what is good for the class-

#1 High performance, low cost racing
#2 Some degree of competition
#3 Safety
#4 Rule stability


I think people need to get past the SIR. It is not the only way to acheive the goals above and in my opinion, would be very bad for the class. Heck, we have only had one real race and the class is less than a year old. Based on the growth I've seen we have a pretty good formula as-is.

Lets leave things as they are and see what happens over the next year. If I were to add/change anything right now it would be to require certain production volume to keep the ducs and Aprilias out.

[u00mem9]

Out of respect for George, and the Massive contribution he makes to this and many other classes, I think no one has mentioned the obvious conflict of interest here...

If a single-sourced restrictor is required and a power commander can be used to keep the engine out of limp mode...we can have ebay engines within 5% of the best engine builder's work.

Any other limitation (engine age, production volume, etc.) sends anyone with the money down to George's shop to optimize the latest thing.

I'm not saying george's info is incorrect, but why ask an engine builder if they think rules reducing the need for their services are a good idea?


Second point:

To keep costs reasonable, a tube frame was a must. I know you are all type-A tough guys, but frankly, the cars are already too fast. FA speeds in a tubeframe open-wheel car will result in trouble. I know, I know, the idea of choking down that performance goes against instinct, but compare the protection level of an F1000 to an FA car. And as the aero begins to mature, the speeds are only headed one direction. Something will have to be changed eventually...hopefully not spurred by the first tragedy.

I support getting a single sourced restrictor in the rules as soon as possible so that manufacturers can incorporate them into the design before more cars are made, and would have to be modified.

Morris

[Wren]

it's not just george saying it, it's anyone with experience with restrictors.