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Discussion Starter #1 (Edited)
Minimum vehicle weights with 275 or smaller tires and 1.8L engine (driver not included): N/A 1805 lbs, F/I 2120 lbs.

Well it seems that there are at least 3 people on here who are at least semi-seriously building SSM cars, so I figured we could pool resources into one thread like the STR and stock classes are doing.

I haven't read through the SM rules all the way through yet, but I have skimmed through most of it.

One thing that caught my eye was 16.1.D.1 "engine block must be a production unit manufactured and badged the same as the original standard or optional engine for that model."

Does this mean that a 2zz swap would not be legal, because the spyder was never offered with it as an optional engine anywhere in the world right?

If so, that leaves turbo or supercharged 1zz as the only option.

I didn't really see anything about trans modifications. can we swap FD's and gears with different C-series transmissions?

Suspension is pretty much unrestricted as long as you use the original chassis mounting points. This means the Battle Version links and spherical bearings are legal. Same with steering, you can't modify the column, but pretty much everything else is fair game.

Other than being able to FI the other big thing is aero.

It seems that everyone runs a BIG ass dual-element 2D airfoil. I would assume this is the way to go, but it does beg the question why not a 3D airfoil?

I think aero is the most uncharted territory with us and warrants good discussion and critical thinking, but unlike the discussion about aero with the track guys we are trying to make as much down-force as soon as possible without much concern for drag, because our speeds will be below 80mph most if not all of the time.
 

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One thing that caught my eye was 16.1.D.1 "engine block must be a production unit manufactured and badged the same as the original standard or optional engine for that model."

Does this mean that a 2zz swap would not be legal, because the spyder was never offered with it as an optional engine anywhere in the world right?
No. The spyder's 1zz was badged toyota, therefore toyota badged motors are legal. 2zz is fine.
 

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It seems that everyone runs a BIG ass dual-element 2D airfoil. I would assume this is the way to go, but it does beg the question why not a 3D airfoil?

I think aero is the most uncharted territory with us and warrants good discussion and critical thinking, but unlike the discussion about aero with the track guys we are trying to make as much down-force as soon as possible without much concern for drag, because our speeds will be below 80mph most if not all of the time.
The only time to use a 3d airfoil is when the rules require you to mount the wing below the roofline. The outer sections that are at a higher AOA help to prevent an equal downforce as the center section to keep the wing efficient over it's span. If you're not limited on how high up you can mount the wing, go with a 2D wing with a gurney flap and some huge endplates.
 

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Discussion Starter #4
No. The spyder's 1zz was badged toyota, therefore toyota badged motors are legal. 2zz is fine.
I guess I'm hung up on the word, "model". The way I read it is the engine must be either the standard engine or an optional engine that was offered for that particular model of vehicle, not manufacture. Does the 2zz pass because its a "ZZ" series engine, or could you put any production engine that is Toyota badged in there?
 

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Discussion Starter #5
The only time to use a 3d airfoil is when the rules require you to mount the wing below the roofline. The outer sections that are at a higher AOA help to prevent an equal downforce as the center section to keep the wing efficient over it's span. If you're not limited on how high up you can mount the wing, go with a 2D wing with a gurney flap and some huge endplates.
Makes sense. SM rules dictate that the rear wing cannot exceed 8 sq/ft, max of two wing elements, cannot be more than 6" in front of the rear axle, 0" past the rear bodywork, 0" past the widest part of the car (not including the mirrors), and cannot protrude more than 6" above the highest part of the roof. That would be the top of the A-frame on a car with no hard top, or the highest part of the HT if you do have one.

Oh and endplates cannot exceed 200 sq/in EACH, with a max of two for the wing.
 

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Makes sense. SM rules dictate that the rear wing cannot exceed 8 sq/ft, max of two wing elements, cannot be more than 6" in front of the rear axle, 0" past the rear bodywork, 0" past the widest part of the car (not including the mirrors), and cannot protrude more than 6" above the highest part of the roof. That would be the top of the A-frame on a car with no hard top, or the highest part of the HT if you do have one.

Oh and endplates cannot exceed 200 sq/in EACH, with a max of two for the wing.
Mount the wing as far back and as high up as the rules will allow. Larger endplates make the wing act like a larger one as it forces more air over/under it. I would say a 63" or 65" wing would be as wide as you would want to go. There was a company that made wings for BMW's a couple years ago that did some testing with a 14" chord as opposed to a 12" chord and found that downforce was increased without a large increase in drag. I can't remember the company now though, but it might be worth looking into if you don't go with a dual element wing.

For endplate effectiveness, here's a quick read about it.
 

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I guess I'm hung up on the word, "model". The way I read it is the engine must be either the standard engine or an optional engine that was offered for that particular model of vehicle, not manufacture. Does the 2zz pass because its a "ZZ" series engine, or could you put any production engine that is Toyota badged in there?
if you could fit a 2jz in a spyder you could run it.

The standard equipment (1zz) was badged and manufactured by Toyota. Therefore Toyota manufactured / badged engines are open game.

I can see where the wording causes confusion.

You could put an echo engine in one if you wanted to. It has been done before:


 

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Mount the wing as far back and as high up as the rules will allow. Larger endplates make the wing act like a larger one as it forces more air over/under it. I would say a 63" or 65" wing would be as wide as you would want to go. There was a company that made wings for BMW's a couple years ago that did some testing with a 14" chord as opposed to a 12" chord and found that downforce was increased without a large increase in drag. I can't remember the company now though, but it might be worth looking into if you don't go with a dual element wing.

For endplate effectiveness, here's a quick read about it.

There you go looking at sound engineering theory instead of the rules again.... :D


I plan to maximize front downforce, then mount the rear wing only as high as is necessary to balance the car, and as far forward as the rules allow. The reason is that the aero rules HIGHLY bias the car towards understeer. The higher the wing is, the greater the moment generated by a given drag force. This tends to remove weight from the front and transfer it to the rear. Similarly, the further back the wing is, the more of the force generated is put on the rear axle. When it is behind the rear axle, it is transferring weight from the front axle to the rear axle.

I plan to make my wing as wide as possible within the rules, take my 15% canard allowance out for the front, and then maximize cord based on that. Net downforce is highest with a longer wing, for a fixed area, than for a longer chord. We have a fixed maximum area to work with within the rules.

It is worth noting that the coanda thrust of a dual element wing is significant, and the line of action of the force is better for balance than it is with the lift force.

Failing better info, I plan to make my endplates flush with the top of the wing at it's highest angle of attack, and shaped on the underside to match the pressure profile expected.

Anyone know why one might choose to louver an endplate? Louvers out and forward or in and rearward to increase the pressure on top of the wing?
 

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Discussion Starter #9
I think the high rear aero bias could work to our favor. Everyone is different, but I find I like a loose car, so I could have my cake and eat it too by having a car that is setup loose and likes to rotate at low speeds and use the monster rear wing to keep the ass planted through slaloms and high speed sections.

I'm glad you mentioned the canard allowance, cause I totally missed that it was part of the total area of the wing allowance. My 2014 rulebook states 15% for the max canard allowance, but I have the solo rules book not the pro-solo.

I definitely need to educate myself about aerodynamics more.

There you go looking at sound engineering theory instead of the rules again.... :D


I plan to maximize front downforce, then mount the rear wing only as high as is necessary to balance the car, and as far forward as the rules allow. The reason is that the aero rules HIGHLY bias the car towards understeer. The higher the wing is, the greater the moment generated by a given drag force. This tends to remove weight from the front and transfer it to the rear. Similarly, the further back the wing is, the more of the force generated is put on the rear axle. When it is behind the rear axle, it is transferring weight from the front axle to the rear axle.

I plan to make my wing as wide as possible within the rules, take my 25% canard allowance out for the front, and then maximize cord based on that. Net downforce is highest with a longer wing, for a fixed area, than for a longer chord. We have a fixed maximum area to work with within the rules.

It is worth noting that the coanda thrust of a dual element wing is significant, and the line of action of the force is better for balance than it is with the lift force.

Failing better info, I plan to make my endplates flush with the top of the wing at it's highest angle of attack, and shaped on the underside to match the pressure profile expected.

Anyone know why one might choose to louver an endplate? Louvers out and forward or in and rearward to increase the pressure on top of the wing?
 

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I guess I'm hung up on the word, "model". The way I read it is the engine must be either the standard engine or an optional engine that was offered for that particular model of vehicle, not manufacture. Does the 2zz pass because its a "ZZ" series engine, or could you put any production engine that is Toyota badged in there?
the model bit is describing the stock engine, that the new engine must be of the same brand as the engine stock engine in the car, or any model variant of the stock car.

for example, if a car came with a base engine clearly ford, but a "hot" version for the same car came with a re-branded volvo engine (im thinking euro focus RS here), then you could put another, different, volvo engine in it.
 

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Discussion Starter #11
the model bit is describing the stock engine, that the new engine must be of the same brand as the engine stock engine in the car, or any model variant of the stock car.

for example, if a car came with a base engine clearly ford, but a "hot" version for the same car came with a re-branded volvo engine (im thinking euro focus RS here), then you could put another, different, volvo engine in it.
Got it. It didn't make any sense to me at first, because I kept thinking of model as in the model of vehicle lol. Makes sense now.
 

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I think the high rear aero bias could work to our favor. Everyone is different, but I find I like a loose car, so I could have my cake and eat it too by having a car that is setup loose and likes to rotate at low speeds and use the monster rear wing to keep the ass planted through slaloms and high speed sections.

I'm glad you mentioned the canard allowance, cause I totally missed that it was part of the total area of the wing allowance. My 2014 rulebook states 15% for the max canard allowance, but I have the solo rules book not the pro-solo.

I definitely need to educate myself about aerodynamics more.

Typo, you are right, 15%.

I see where you are coming from, and I won't know until I get some stuff on the car and try it how I feel about that. Right now all I know is that unbalanced aero provides increasing bias change with increasing speed, and I want more aero at the rear by some amount because high speed oversteer is slower. I have been presuming that with something around an order of magnitude more downforce allowed at the rear than front, I will not want to drive around maximized rear downforce within the rules. I am certain that I'll take the hit on being all the way forward within the allowance, and I'm certain I'll try all the way up within the allowance.
 

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What are the SSM rules in regards to a front splitter?
 

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What are the SSM rules in regards to a front splitter?

The rule book (available as a pdf on the scca website) is pretty clear on that. The only aspect that isn't clear is the following:

My read was option A below. The rules clarification came out as option B below. So B it is. Language is a little awkward, but if they fix it, it will reflect B. Protests at 2013 nationals followed B, that's evidence enough for me.


Otherwise, must be a flat plate within 3 degrees plus minus of horizontal, can't extend rearward of the front axle centerline. I'm agonizing over how to approach the +/- 3 degrees :D
 

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Discussion Starter #15
Thanks for the clarification. I had been interpreting it as B until I saw something yesterday that made me starting thinking like you were.

The rules say that the splitter must be a flat plane, but could you make vertical end plates that extend forward, away from the bumper (I'm assuming a max of 6") that follows the splitters edge to keep air from spilling off the sides of the bumper maximizing the efficiency of the splitter? You'd just have to leave a small gap between the two so they were technically two separate pieces, or would a canard do essentially the same thing with less drag?

Example of what I'm thinking.



I'm thinking the splitter should be raked up at the rear to create low pressure and a small diffuser effect, but its gonna have to be unstreetably low to the ground for that; less than three inches.

The rule book (available as a pdf on the scca website) is pretty clear on that. The only aspect that isn't clear is the following:

My read was option A below. The rules clarification came out as option B below. So B it is. Language is a little awkward, but if they fix it, it will reflect B. Protests at 2013 nationals followed B, that's evidence enough for me.


Otherwise, must be a flat plate within 3 degrees plus minus of horizontal, can't extend rearward of the front axle centerline. I'm agonizing over how to approach the +/- 3 degrees :D
 

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No rake allowed. +/-3 degrees tolerance allowed because you have to define horizontal in a way that is protest defensible. I think those end plate looking things are being used as part of the canard allowance. It seems a little silly to me to make them so tall unless there is also an intention to get a low pressure bubble in the front wheel wells out of them too. I want to get an idea of the airflow direction and velocity at the sides of the nose before deciding how to approach that. Another way to get such elements in within the rules is the fact that the bumper is a wide open mod allowance.
 

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Discussion Starter #17
I know it isn't allowed, but you could use the 3* tolerance to provide minimal rake.

By the way Richard, how is the spool on that 6258? I'll be going the cheapo route with a k03, but I'm kinda worried it will run out of steam at 7500rpm. They are so tiny!

No rake allowed. +/-3 degrees tolerance allowed because you have to define horizontal in a way that is protest defensible. I think those end plate looking things are being used as part of the canard allowance. It seems a little silly to me to make them so tall unless there is also an intention to get a low pressure bubble in the front wheel wells out of them too. I want to get an idea of the airflow direction and velocity at the sides of the nose before deciding how to approach that. Another way to get such elements in within the rules is the fact that the bumper is a wide open mod allowance.
 

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Discussion Starter #18
Updated first post with minimum vehicle weights for FI and NA 1.8L engines on 275 or smaller tires.

Seems like the 275/35R15 hoosiers would be the way to go with the -200 lb weight allowance.
 

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Discussion Starter #19
Any thoughts on intercooled vs. non-intercooled + E85 for max weight savings? Keep in mind FI cars have a minimum weight of 2120, which shouldn't be too hard for us to achieve.
 

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I know it isn't allowed, but you could use the 3* tolerance to provide minimal rake.


By the way Richard, how is the spool on that 6258? I'll be going the cheapo route with a k03, but I'm kinda worried it will run out of steam at 7500rpm. They are so tiny!
Money no obstacle, I'd do sequential twin turbo, but for the (steep, but within reach) price, I'm happy. Unscientific estimation: The response is a hair better than a GT2560 (not as good as a GT2554 with equivalent exhaust, etc) with no compromise of the top end power for a given boost level. It makes 1.5 psi at 1500 rpm. Response becomes snappy just above 3k with OEM NA/emissions tuned VVT-i control. I'm hopeful that will shift down about 400 rpm with good vvt-i tuning. By 3800, the slope of the boost curve passes through the slope of the TPS curve in the data log when I "floor it" (not roll on the throttle).




Updated first post with minimum vehicle weights for FI and NA 1.8L engines on 275 or smaller tires.


Seems like the 275/35R15 hoosiers would be the way to go with the -200 lb weight allowance.

If I were running dot r comps, I'd run the 255-40-13 on a 13x10+. Exact same width, more area under the curve at the expensive of more shifting, lowers the car more without screwing up the suspension, and automatically raises it for street use.


Any thoughts on intercooled vs. non-intercooled + E85 for max weight savings? Keep in mind FI cars have a minimum weight of 2120, which shouldn't be too hard for us to achieve.
I think you answered your own question. For a non-street driven car, an intercooler is pretty damned good ballast. Can you drive up to a pump and buy E85 anywhere you go where you live? If you are doing a serious build, both? 400 ft-lb is roughly the threshold to spin that hoosier in second by rolling on throttle in a straight line. Can you make that from the slowest corner in second to redline? :D
 
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