ah, ultimate bench racing

some of that info like wheelbase etc can be found here:

http://spyderchat.com/comparisons.htm

 

Awsome!

i need to research gear ratios and final drive


Thanks

Andres

 

gear ratios are located here:

http://spyderchat.com/specifications.htm

i know you have a dyno plot or two

 

i think you could assume 1:1 (or maybe .9:1) for motion ratio since we are macpherson strut cars

 

Thanks so much, this might be interesting....

Andres

 

Lapsim partial results.....

This is really cool, my friend wrote: (based specifically on my car's specs)

" Andres,
I've got some initial results back. Some caveats first though. Lapsim is not the final word on how well a car is going to do in autox. It's a just a tool and it was originally designed for road racing. It doesn't do slaloms very well. It keeps trying to turn them into straights. I give it speed and lateral G data from an autox course and it turns it into a closed loop road course with similar corners and speeds. A narrower car will drive a slightly different path through a course with the turns not being quite as sharp as those taken by a wider car. Lapsim assumes all cars take the same path.

The full version of Lapsim costs something like 10,000 Euros. I use the free version. Because I'm working with the free version, there are some assumptions that have to be made:
1) Everyone is able to get their suspension to work equally well.
2) All tires share the same characteristics.
3) Everyone's differential works the same

Additionally, I assume:
1) Aerodynamic lift is 0 for all cars
2) All cars generate the same peak lateral G (I've looked at data from heavy and light cars. This appears to be close to true.)
3) There's not much more power to be found in stock S2000 motors than they already produce.
4) The CG height of your Spyder is the same as that of my STS Miata.

Also note that there's optimizing of the setups that can be done to fine tune these results.

With all that said, and using a Lincoln MidDiv course from 2 years ago, the reigning champ in Lapsim STR is the AP2 S2000. Your Spyder is only 0.07 seconds behind though. The Spyder's advantage is in the tighter curving sections. The S2k pulls ahead in the long acceleration zones. On this particular course, the Spyder shifted to 3rd three times, but only one was long enough that you'd probably do it in real life. The S2000 shifted down to 1st once and up to 3rd once.

There's a little more fine tuning to do. I'll work with it some more later and get you some charts and graphs, but my initial take is that the Spyder can probably be a player in STR. Both the Spyder and S2k drivers will need to be able to shift on course though.

Hope this helps."

Lets see what else he finds out...

Thanks to Dan too !!

Andres

 

This is really cool, my friend wrote: (based specifically on my car's specs)

" Andres,
I've got some initial results back. Some caveats first though. Lapsim is not the final word on how well a car is going to do in autox. It's a just a tool and it was originally designed for road racing. It doesn't do slaloms very well. It keeps trying to turn them into straights. I give it speed and lateral G data from an autox course and it turns it into a closed loop road course with similar corners and speeds. A narrower car will drive a slightly different path through a course with the turns not being quite as sharp as those taken by a wider car. Lapsim assumes all cars take the same path.

The full version of Lapsim costs something like 10,000 Euros. I use the free version. Because I'm working with the free version, there are some assumptions that have to be made:
1) Everyone is able to get their suspension to work equally well.
2) All tires share the same characteristics.
3) Everyone's differential works the same

Additionally, I assume:
1) Aerodynamic lift is 0 for all cars
2) All cars generate the same peak lateral G (I've looked at data from heavy and light cars. This appears to be close to true.)
3) There's not much more power to be found in stock S2000 motors than they already produce.
4) The CG height of your Spyder is the same as that of my STS Miata.

Also note that there's optimizing of the setups that can be done to fine tune these results.

With all that said, and using a Lincoln MidDiv course from 2 years ago, the reigning champ in Lapsim STR is the AP2 S2000. Your Spyder is only 0.07 seconds behind though. The Spyder's advantage is in the tighter curving sections. The S2k pulls ahead in the long acceleration zones. On this particular course, the Spyder shifted to 3rd three times, but only one was long enough that you'd probably do it in real life. The S2000 shifted down to 1st once and up to 3rd once.

There's a little more fine tuning to do. I'll work with it some more later and get you some charts and graphs, but my initial take is that the Spyder can probably be a player in STR. Both the Spyder and S2k drivers will need to be able to shift on course though.

Hope this helps."

Lets see what else he finds out...

Thanks to Dan too !!

Andres

S2000's in STR make quite a bit more power than they do stock.

 

cool!

the assumptions made seem reasonable enough to me

I am curious which dyno curves where used - if you have time post them

 

cool!
I am curious which dyno curves where used - if you have time post them

That's classified...

Andres

 

Wheelbase: 96.7"
track width (depends on tires and wheels, yours are not the same as listed on the specs page!)

spring motion ratios are around 0.96 front and rear. front swaybar motion ratio is ~0.58, rear is about 0.96.

I never did tip tests to determine Hcg, but having worked on both, I'd expect the spyder to come in at least half an inch or so below an sts miata.

things that are missing that are suspect to the validity of the model. Didn't ask for:

data on polar moment. this makes for a big difference in transients. (favors the spyder, if the driver has the skill to take advantage.)

front and rear track widths separately. This can make a big difference. Looks to favor the spyder by 2.5" from the s2k, and 1.5" from the nc. if these numbers are even close to correct, this is simply HUGE.

Bump and roll steer behavior, etc etc etc.

Tire diameter (this affects the effective drive ratio, and the 3 cars don't use the same rolling diameter, so it will make a difference). If the program doesn't ask for it, the final drive can be fudged to account for it.

Also, what are you using for redline? 6850 is the spec, but you can easily get to 7100 in 1st and 2nd in most cars.

edit: I see your new message. That not accounting for path differences due to width thing is huge. It is wrong to ignore that for autocross, thought at much larger corners/higher speeds, it isn't very important. That is probably a bigger error than the more wrong assumption that all the suspensions are equally effective in all situations. It would be nice to at least know which way the error due to ignoring width will be. The rear track width dominates, so the car that is narrowest in the rear will have an advantage not shown in the sim. Looks like the stock widths are 2.5" in favor of the spyder over the s2k and 1.5 over the NC. Not sure how that changes with race tires and camber on the s2k and NC.

another question... does the free version overlap braking, acceleration, and cornering, or segment them? this simplification isn't as bad for road racing as for autocross. this error would also undersell the spyder. Of course the tire and power assumptions really favor the s2k (as in, they should do better than the sim assumes).

Also, peak g loads from a DAQ are misleading. better to take the highest g's in any direction that is sustained for over a half second or so.

 

Lol, I know I was going to hear from you..

These are my numbers: the others are the same from the specs' post

136 whp@ 6700rpm
119 lb-ft@ 4400rpm
Wheelbase 96.5 in./153.0 in.

Track width 168.5 inch front / 168 inch rear
[FONT=&quot] Total weight 2080 lbs[/FONT][FONT=&quot]
Front/rear weight distribution 47/53 [/FONT]
Spring rates and motion ratios: front 8 kgf/mm (444.2lbs/in)
[FONT=&quot] Rear 6 kgf/mm (336 lbs/in)[/FONT][FONT=&quot]

He was trying to be nice I thing he's not done, will see what he comes up with to make me feel better

Thanks Richard, actually you might be able to improve the info

Andres

[/FONT]

 

Your total weight is probably to low.

 

Sorry that's my car's weight...arty:

Andres

 

2080 is a reasonable weight - i think it is his actual weight

a year ago i came in a 2115, with only coilovers, rpf1's, catback, all stock otherwise, +3/8 tank fuel, this was on scca scale according to my co-driver who put the car up on the scales

the car should weight a little big less now

 

THe big one that will affect lap times is tires. I have not looked it up but can we run the same maximum width of tire that your can run on a S2000? Very interesting program and thanks for showing us what available out there.

 

It is way more complicated than that. A simplification I can live with:

the less power the car has, the smaller a diameter you can get away with

the lighter the car, the narrower the ideal width, and the less compromised an even narrower width is.

So the spyder can't fit as wide or as big a diameter as the s2k, but it is lighter, with less power, and better rearward weight transfer. That means you can't easily infer which car is less handicapped for tire size. It could be any one of the 3 cars actually.

I think (just my informed opinion, not a statement of fact) that the rear track width, and area under the power curve of interest to weight ratio are more important than the relatively small tire differences.

 

i like this kind of conversation we are having here

roc, i never had considered the rear width that important, but yes I could see how important it is esspecially in slaloms

its making me want to go out and race

 

I ran the numbers... actually I cheated and used CAD to simulate it (but I used 58" as my track width...so there might be an error here). Anyway, with a 400 ft corner radius, any rear track width wider than 1" narrower than the front is hurting your times. Theoretically, it gets worse linearly with radius, so that it is 2" on a 200 ft radius.

Many cars are wider in the rear, but that is mostly because people generally think it looks better. Purpose built race cars are often narrower in the rear than front even for road racing speeds where wider is better, depending on the rules they are stuck with.

There is also a compounding effect that is prominent at autocross speeds where, if you can make the front wider by only a little bit, and because of caster jacking, it should improve performance in very tight corners without narrowing the rear or widening the front more than is useful for more open corners/ fast slaloms. Give Andres and me a couple days to work on that and I'll post something up about it.

 

I've been going through the 2011 STR rules. So far I found a tiny improvement in handling, and ~4 hp for Andres. I'm sure there is more.

 

I love Spyderchat.. .:rockon::rockon:

Andres

 

I'm hung up on this: Reprogrammed ECU (via hardware and/or software) may be used in the standard housing.

people are using this to say they can run a megasquirt in the stock ecu case. by itself, I buy that. What other restrictions prevent it? The ecu has to talk to the OBD2 port, and generate/ communicate fault codes..... anything else?

Anybody cracked open our ecu case? How much space is there in there? We basically need to adjust fuel trim, advance ignition timing, and up the rev limit. Could we cut up something like an e-manage ultimate and rewire it in the voids in the stock ecu?

 

Anybody cracked open our ecu case? How much space is there in there? We basically need to adjust fuel trim, advance ignition timing, and up the rev limit. Could we cut up something like an e-manage ultimate and rewire it in the voids in the stock ecu?

if people are sticking megasquirts in there, then piggyback should be ok

but would piggyback allow you to raise the rev limit?

 

also:


Fuel pressure regulators may be replaced in lieu of electronic alterations to the fuel system. It is not permitted to electronically modify the fuel system AND replace a fuel pressure regulator.

with a good exhaust and intake, can we use more fuel everywhere? With a returnless system, would our fuel pump be considered the pressure regulator, or the injector


VTEC controllers and other devices may be used which alter the timing of factory standard electronic variable valve timing systems.

Can we get any power out of a camcon with just intake and exhaust work to support it?

 

whats the tiny handling improvement?

 

Why can't you just put the internals of the PowerFC inside the OEM ECU Case? That is similar to putting a megasquirt inside a stock case.The stock wiring harness plugs right in. If you don't connect the commander no one would even know it was a PFC. With proper tuning the PFC would not only raise the redline but can also probably add 15-20hp with a proper header and intake.

I don't have a 1zz ECU or PFC but I bet the cases are probably the same size.

 

possibly, but these are the rules we have to follow:

F. The engine management system parameters and operation may be
modified only via the methods listed below. Any and all modifications
must meet or exceed the applicable EPA tailpipe emissions standards
for the year, make, and model of the car. These allowances
also apply to forced induction cars, except that no changes to standard
boost levels, intercoolers, or boost controls are permitted. Boost​

changes indirectly resulting from allowed modifications are permis

​

​

sible, but directly altering or modifying the boost or turbo controls,

either mechanically or electronically, is strictly prohibited.
1. Reprogrammed ECU (via hardware and/or software) may be used
in the standard housing. Traction control parameters may not be
altered. Altered engine controllers may not alter boost levels in
forced induction engines. Alternate software maps which violate
these restrictions may not be present during competition, regardless
of activation.
2. Electronic components may be installed in-line between an engine’s
sensors and ECU. These components may alter the signal
coming from the sensor in order to affect the ECU’s operation of
engine management system. Example: fuel controllers that modify
​

​

the signal coming from an airflow sensor.
3. Fuel pressure regulators may be replaced in lieu of electronic alterations
to the fuel system. It is not permitted to electronically
modify the fuel system AND replace a fuel pressure regulator.
4. Ignition timing may be set at any point on factory adjustable dis​

​

​

tributor​

ignition systems.

5. VTEC controllers and other devices may be used which alter the
timing of factory standard electronic variable valve timing systems.
6. All vehicles must comply with the EPA tailpipe emissions test requirements
as a minimum.​

​

​

does swapping out the entire ecu count as "reprogrammed via hardware"?​

​

​

 

actually, the above might not matter after this year

check out the new fast track - ecu tuning may be as simple as getting an emanage piggyback next year