Had some awesome discussion going on the other thread but it seemed like too many topics were being discussed.

I found the discussion on power, and especially weight bias very educational and would like to know more about the possibilities there. Here's a few of my (nearly worthless) comments on the 2 subjects...

Weight bias:
Increasing front bias seems at odds with most of what I've heard and read about car setup. While I can see how increasing weight over the front axle would help with acceleration, wouldn't handling suffer? It's already tough to get enough oversteer out of a FWD. How would you guys approach this?

Power:
Lots of big power ideas being tossed around on this board, and even a few already implemented. The thing is, it seems like the more simple solutions are the ones which prevail lately. The most successful cars have all had fairly straightforward (in my experience) designs under the hood, with the Janusz/Shenefield Civic being the most exotic NA build that I know of. Is it only coincidence that the NA cars have been outperforming the boosted cars?

K series is the "big thang" in terms of power these days, but I've "heard" that a K series install moves weight further rearward. In this brave new world, that might be a bad thing. So what about an H series. They're heavier than a B by about 40 lbs, but they definitely will move weight forward due to their position in the engine bay.

The most interesting discussion to me is how much power it takes to justify a 100 lb weight penalty, or whether it can be justified at all. Thanks y'all for the great discussion.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 &raquo;</TD></TR><TR><TD CLASS="quote">
Weight bias:
While I can see how increasing weight over the front axle would help with acceleration, wouldn't handling suffer? It's already tough to get enough oversteer out of a FWD.

</TD></TR></TABLE>You came close to why the concept could work in the first sentence, and then ran screaming away from it with your hands over your ears in the second.

Taking weight off the back and moving it toward the front would decrease rear grip and also decrease the tendency for the car to get into tank-slappers, which is something a lot of the stiff, oversteery FWD's can have problems with. Traction under acceleration is the big bad problem facing FWD's and solving that problem could help a lot with getting from element to element. I like the idea a lot.

 

Well, if it were me building a FWD SM car, I might look at the loads involved on each of the wheels, and how to optimize things statically so it works well dynamically.

There's a few things you know - your car is going to weigh 1800lbs. NA or 1900lbs. FI. It's going to have a wheelbase you can't really change (say 98"), and a CG height you're going to get as low as possible - use 15", for example. Let's say we have two 1800lb. cars with the same wheelbase and CG height, but one has 60/40 weight distribution, and the other has 75/25.

The barnstormer motor you build is going to be capable of a certain thrust based on your torque output, gearing, and tire diameter. That thrust curve, divided by the car's weight, is its theoretical acceleration, assuming good traction. It would be illuminating for a potential SM competitor to plot their acceleration vs. speed curve for themselves and their competitors, to see how they stack up. Depending of course greatly upon gearing, an 1800lb. car only needs to make about 200 ft-lbs. of torque to be capable (on paper) of 1g forward acceleration in second gear.

The problem with FWD, is that as you accelerate harder and harder, you move more and more weight off the drive wheels. Using the example above, at rest or at constant speed, our FWD car is going to have (1800*.6 1080 pounds on the front wheels for the 60/40 car. Now as we start accelerating, let's say to .5g, we only have ((1800*15*.5)/(98) ~= 140 pounds of rearward weight transfer. So those poor front wheels now have ~13% less load (940 vs. 1080) to perform further accelerative and turning duties.

So what can we do to minimize this? Well, our 75/25 car undergoes the same rearward weight transfer at that acceleration, but even then, it has a load on the fron tires of (1800*.75)-140 = 1210, so still a good bit more load than the 60/40 car had at rest.

You'll note the drag guys do everything they can to get weight forward and to minimize the rearward weight transfer. Things are mounted low, the battery is up in front of the right front tire, and the wheelie bars effectively lengthen the wheelbase, growing the denominator in our weight transfer equation.

Sure, a front-heavy car has more weight to get around the corners too, but at that point it might make sense to step up to the next size tire, like a 285/30-18. That size tire seems to be perfectly happy holding up the front 1300 pounds of Vic's 2600lb. M3, and in putting down well over 200whp on the back of the heavier DSP BMW. Thus, it should be happy holding up ~1350 pounds on the front of an 1800lb. SM Civic.

If I were the type of masochist to try and build a FWD SM car, it'd probably be a 3rd gen (John Thomas era) Civic with a stock-ish K series. Tiny little fuel cell, itty bitty rear brakes, tires and suspension bits... big heavy battery way up front, front splitter made of lead, etc. until the weight minimum is met. Starting with an underweight chassis gives you more room to tailer and tune weight distribution.

Good luck to all SM participants, FWD, RWD, AWD! Looking forward to running against you all next year.

 

I agree almost completely with jzr... except that I'd use the era prior to the 84-87 Civic...the 80-83. From what Sean tells me, it's strut at all 4 corners, and is even narrower than the 3rd gen cars.... both things that I'd like. The torsion bar system works, but I don't like it. And I'd build a bit crazier K series, if for no other reason because you can can do more than 1 G acceleration sometimes, and the traction control will be able to control it when you can't utilize the extra power. Real race oriented TC is definately a must for any FWD SM car IMO.

Either way...build it as light as possible, and ballast it to weight min. Things like a lower control arm brace would be nice to make out of lead...ya know... to dampen those nasty vibrations and harmonics Exhausts are another good place to not worry about weight, since a bit more thermal efficiency is a good thing, and the weight is certainly low. Keep the lightweight exhaust tubing for the stock class guys wanting that last 2 lbs off the car.

Remember fuel cells have to be within 10% of the original volume...luckily, the older civics didn't have huge tanks to begin with.

As for an overly light rear end....even better, keep silly little lightweight cheap 195s or 205s in the rear on a set of 13s. They're just keeping the rear bumper cover from scraping anyway. Also, I'd keep the front and rear track widths pretty even...so if I put 285s upfront, I'd push the rears out a bit to compensate, and help with keeping the fronts on the ground.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TeamSlowdotOrg &raquo;</TD></TR><TR><TD CLASS="quote">You came close to why the concept could work in the first sentence, and then ran screaming away from it with your hands over your ears in the second.
</TD></TR></TABLE>

Heh, story of my life!

But still, wouldn't lateral acceleration suffer?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 &raquo;</TD></TR><TR><TD CLASS="quote">

Heh, story of my life!

But still, wouldn't lateral acceleration suffer?</TD></TR></TABLE>

lateral acceleration suffers, yes...compared to an otherwise identical car with 50/50 weight balance. However, when everyone else is currently running 225s and you're running 285s, you make for it, and more. Hence the reason to go bigger than 13s or 15s for the front of the car.

 

Yeah, but how the heck do we fit them??

To me it looks like the track width on the M3's is already close to what I have with my little 13 x 9's. We can't bang out the inside of the wheel well so 285's on a larger wheel are really gonna stick out! I'm thinking that would add an easy 4" to the track width as well as raising COG at least 2" or so. There just wouldn't be any other way to fit the wheels under the car (that I know of).

I guess we need to find the "balance"...

 

Using such a drastic front biased setup will give you a huge yaw moment of inertia (inertia of car when its spinning), which I think is the worst thing to have in an autocross car. Autocross courses are typically full of tight quick cars and quick rotation is key...low yaw inertia is a much more nimble car capable of turning fast, and (though seemingly counter-intuitive) will be less likely to completely spin out.

This all sounds great for a great accelerating setup, but a chassis needs to do two things: move quickly in a straight line and rotate. A 75/25 car does the first better but seriously hampers the second.

Edit: I don't race SM so it may be the case that the only way to catch the bigger RWD cars is to increase accel capability at the expense of handling, but I can't imagine the trade off would be worth it.


Modified by GSpeedR at 11:59 AM 7/6/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 &raquo;</TD></TR><TR><TD CLASS="quote">Yeah, but how the heck do we fit them??</TD></TR></TABLE>Have you measured the absolute width of your car presently? FWIW the big tire guys that I've looked at out west are running widths in the 72-74" range. Thomason's Z06 is pushing 76" wide in the rear. Makes it a PITA to load on my little trailer...

A chassis that allows you to keep the front somewhat low or narrow once the fenders are out of the way would be a good thing. You'd have to go around looking at fenderless Civics to find the chassis that had the unibody the least "in the way" of the front tires.

 

Subscribing

 

Heh, I'm wondering how long it'll be until Jesse has me taking measurements of the wheel wells of my '83 Civic to see how much tire it can fit...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jzr &raquo;</TD></TR><TR><TD CLASS="quote">Have you measured the absolute width of your car presently? FWIW the big tire guys that I've looked at out west are running widths in the 72-74" range. </TD></TR></TABLE>

I recall a "Wide Load" sticker on someone's vette one time...

I haven't measured my Civic on the race wheels yet, but having looked at the M3's, the track width on those things seems surprisingly narrow. Without the flares (like Sias is running), I'd say an M3 on 9"+ wide wheels is similar in width to my Civic on 9" wheels. Besides weight, a narrow profile seems to be one of the only advantages a FWD Civic might have in this class.

I'm just trying to understand this new (to me) idea more fully. Without having the technical knowledge (like Gspeed) to back it up, it seems like the effort to move weight bias forward in order to aid acceleration tends to negate the few advantages FWD's currently have in the class.

Maybe a compromised setup with bias a "little bit" further forward, and wheels "somewhat" larger would be the ticket. I guess that's where the T&T comes in...

 

Did you guys not read Chris's stuff on in the other thread about how your only at max accel about 20 percent of the time? So why set up a Sm car thats baised toward acceleration? The said car in theory work better in a straight line, and accelrating out of turn but thats only a small part of the battle. But what about braking and braking with transitions?(i bet it would be just a little tailhappy with the typical suspension setups all of us run).

I do really like the idea of larger than 15 inch wheels in the front. That migth make the said setup work(the heavy front idea), and would probably even help out the current top level Sm cars running around.

Keep these stuff going maybe the collected brain trust of honda-tech can get one of these cars to trophy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 &raquo;</TD></TR><TR><TD CLASS="quote">Yeah, but how the heck do we fit them??

To me it looks like the track width on the M3's is already close to what I have with my little 13 x 9's. We can't bang out the inside of the wheel well so 285's on a larger wheel are really gonna stick out! I'm thinking that would add an easy 4" to the track width as well as raising COG at least 2" or so. There just wouldn't be any other way to fit the wheels under the car (that I know of).

I guess we need to find the "balance"...</TD></TR></TABLE>

Hence why both jzr and myself are advocating using cars that are Narrower than EF/EG/EF Civics. If you start with a narrower car, you can move the wheeels further out without having the issues of track width becoming overly wide. The 2nd gen Civic is something like 4" narrower than a EF....

Also, custom spindles/control arms can help keep the tires in a bit tighter. Even using different brakes where the calipers are further inward by a few mm could help on getting it narrow.

The custom spindles, combined with a lowered and drysumped K series will get the CG back down. The nice thing about the K series is that the exhaust manifold exits out the back, meaning you don't need clearance for a header to go under the motor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">Using such a drastic front biased setup will give you a huge yaw moment of inertia (inertia of car when its spinning), which I think is the worst thing to have in an autocross car. Autocross courses are typically full of tight quick cars and quick rotation is key...low yaw inertia is a much more nimble car capable of turning fast, and (though seemingly counter-intuitive) will be less likely to completely spin out.

This all sounds great for a great accelerating setup, but a chassis needs to do two things: move quickly in a straight line and rotate. A 75/25 car does the first better but seriously hampers the second.

Edit: I don't race SM so it may be the case that the only way to catch the bigger RWD cars is to increase accel capability at the expense of handling, but I can't imagine the trade off would be worth it.


Modified by GSpeedR at 11:59 AM 7/6/2005</TD></TR></TABLE>

I also advocate keeping as much moment of inertia as possible for this very same reason. That little 25% of the weight in the rear should be as far back as possible. And keeping the front weight really towards the front. You can also play with suspension geometry a bit and get positive engagement when you start sliding. I'm still not quite clear how that works, but it's feasible.

I'll try and get Jim to post about it if he gets the chance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mattamotor &raquo;</TD></TR><TR><TD CLASS="quote"> Did you guys not read Chris's stuff on in the other thread about how your only at max accel about 20 percent of the time? So why set up a Sm car thats baised toward acceleration? The said car in theory work better in a straight line, and accelrating out of turn but thats only a small part of the battle. But what about braking and braking with transitions?(i bet it would be just a little tailhappy with the typical suspension setups all of us run).

I do really like the idea of larger than 15 inch wheels in the front. That migth make the said setup work(the heavy front idea), and would probably even help out the current top level Sm cars running around.

Keep these stuff going maybe the collected brain trust of honda-tech can get one of these cars to trophy.</TD></TR></TABLE>

1) No offense to Chris, but I don't buy the idea of only at max accel 20% of the time, especially with the setup that I'm talking about where you can actually put down power. Watch some in-car from Andy McKee, and it certainly looks like he's accelerating like a badass for awhile. I've also driven a 200+ whp fwd SM car and you accelerate more than that IMO. Also, the more power is beneficial in that you can build the car to only use 1st and 2nd...or possibly just 2nd or whatever... Needing 3rd is just costing time. Watching Tunnel bounce off the limiter in the M3 a bunch in Oscoda made that quite apparent.

2) As far as biasing it towards acceleration.... consider that the plan is to have an low CG 1800 lb car with 285 trying to turn it. Compare this against the competition, which is currently a solid 500+ lbs heavier, using the same tires to try and turn it. The car is going to be able to carry more max lateral G just from the weight. So we move past that, and try to make up for where a little FWD car is going to suffer against the competition....accelerating.

3) Braking... 285s upfront with a lot of weight on them... sounds like it'll stop pretty darn well. Using a bias adjuster to get it to not spin under braking.

4) "typical suspension setups"... This is SM...not SP. Think outside the box. Why use the typical suspension for a car built around an entirely different design intent? It's a package thing...gotta build for the design intentions.


Modified by PseudoRealityX at 2:08 PM 7/6/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PseudoRealityX &raquo;</TD></TR><TR><TD CLASS="quote">I also advocate keeping as much moment of inertia as possible for this very same reason. That little 25% of the weight in the rear should be as far back as possible. And keeping the front weight really towards the front. You can also play with suspension geometry a bit and get positive engagement when you start sliding. I'm still not quite clear how that works, but it's feasible.

I'll try and get Jim to post about it if he gets the chance.</TD></TR></TABLE>

So you are trying to get as high as an inertia as possible? Crazy.

I admit, you do have to think a bit backwards for an extreme FWD racer, but I still think that there are going to be big problems with having 2 wheels do all the work.

1. The high moment of inertia with very little rear grip would be a handful in a quick transition (ie a slalom). The car would be reluctant to turn at first, and then once it does it will be reluctant to stop turning. The very low weight on the rear tires just makes it that much more difficult to drive.

2. Much stiffer springs up front. This leads to more front lateral weight transfer (front biased roll moment distribution), and you will be reducing a lot of the front grip that you worked hard to acheive. Stiffer springs means different camber curve, bumpsteer, etc. so the suspension geometry would need changing (which is ok).

3. All braking done up front. This is only bad IMO since the rears aren't doing anything and so your lateral grip will suffer when braking and turning. With the rears contributing little force in any direction, the fronts will be able to generate less lateral force since they will be generating more braking force. If the rears were doing some of the braking, the fronts have more grip available (traction ellipse) for lateral grip. Striaghtline braking would probably improve a lot with the big tires and lots of weight on them, but you guys are turning while braking.

4. Big tires weigh a lot and you're hindering the acceleration you wanted to get. The really light FWDers are probably really underpowered compared to the big Beemers, so maybe this is a big deal.

So I personally think that if you are able to get a super low CG and super low weight, then the 60/40 weight bias is as front biased as you want to get. I agree that wider are almost always a good thing, but tire grip also depends on temperature, so I would want to find a good compromise between vertical load and temperature for a certain width.

Hopefully others can add good/bad things I missed or argue with the stuff above. I am stuck in the RWD mindset lately (FSAE) so it's cool to talk about different *****.

 

Our 75/25 car is only going to have 450 pounds on the rear axle (not counting driver) at rest. 1g braking is a pretty good target - at that rate, we have ~280 pounds of forward weight transfer. Leaving 170 pounds on the rear axle.

Summary: ditch the rear brakes entirely, think of the unsprung and rotational weight savings! Emergency brake can be a cantilever deal off a BMX bike or something to clamp a front axle.

The motor going into this FWD SM car needs to be powerful enough to just be able to spin the driven wheels (even if they're covered in 285s) on a sticky surface, at any speed from 30-65mph in second gear.

Since the rear is only having to move 450 pounds around a corner, something tells me it'll be hard to make the car loose, even with the inside rear perpetually airborne.

I think the front-heavy car vs. a more "traditional" 60/40 car will suffer under braking, have an advantage under acceleration, and have a slight disadvantage in steady-state cornering that I believe can be worked around in changing tire size paradigm. If we looked at a g-circle diagram of a top FWD SM car vs. a top RWD SM car, I'd bet the biggest deficit is in the "powering out of a corner" areas, and the big-shouldered, front-heavy car's goal is to reduce that gap, while working to maintain the advantages in steady-state cornering.

(Of course, it's easy for me to theorize on a web forum, and another matter entirely to actually go spend the $ to test it...)

 

Ok. I dont get it. I mean i'm all for thinking "outside the box" but i just dont see why building an extreme SM fwd car would be THAT much different from a CSP or an EP car. Yes, the 200lbs (12.5%) or so extra weight an SM car has to carry changes things but not THAT much. These are all good ideas on paper, but IMO, would just destroy the inherent advantages of a small FWD car, ie lightweight and nimbleness.

FWIW, and I maybe in the minority here, but i seriously think most of you are barking at a tree on the other side of the forest while standing in the shade of the one you really want. SM allows plenty of mods that would improve the cornering momentum of these cars. Think custom lightweight spindles, control arms, brakes to minimize unsprung and overall weight. Ballast it low and in the center, where that mass belongs.

Hell, there's a reason why CSP cars are as fast as SS Vettes and almost as fast or faster then most of the current crop of SM cars. You just gotta take it to the next level with the SM allowances.

Look at the fastest SM Civics so far on the Tour this year. I see much more EP/CSP there than what's being proposed in this thread. And I KNOW they will get MUCH faster VERY soon.

But anyways, regardless... isnt this the beauty of SM? So many possibilities for creativity?

Keep it going.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jsi &raquo;</TD></TR><TR><TD CLASS="quote">Ok. I dont get it. I mean i'm all for thinking "outside the box" but i just dont see why building an extreme SM fwd car would be THAT much different from a CSP or an EP car. Yes, the 200lbs (12.5%) or so extra weight an SM car has to carry changes things but not THAT much. These are all good ideas on paper, but IMO, would just destroy the inherent advantages of a small FWD car, ie lightweight and nimbleness. </TD></TR></TABLE>

If you're not using every allowance to your advantage, then you're not building to the extreme, right? Isn't the POINT of having things like "unlimited drivetrain" and "suspension is open as long as you don't move the pickup points" good enough reasons to engineer yourself something that works BETTER? EP isn't really a good thing to follow, since they can relocate their suspension, and the computer controls don't allow TC and such, so they're a bit more limited on what can be done in terms of power.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">FWIW, and I maybe in the minority here, but i seriously think most of you are barking at a tree on the other side of the forest while standing in the shade of the one you really want. SM allows plenty of mods that would improve the cornering momentum of these cars. Think custom lightweight spindles, control arms, brakes to minimize unsprung and overall weight. Ballast it low and in the center, where that mass belongs. </TD></TR></TABLE>

You're gonna reach a point where you simply NEED power and NEED to put it down to overcome cars with 3x as much power that aren't THAT much lighter. You're gonna need to get out of the hole in 2nd gear "nearly" as quick as an EVO or M3. A regular CSP car isn't gonna do this. Even with more power...IMO. It's also not going to be able to run anything bigger than a 13 x _ without some rethinking on how to keep the rideheight low enough.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Hell, there's a reason why CSP cars are as fast as SS Vettes and almost as fast or faster then most of the current crop of SM cars. You just gotta take it to the next level with the SM allowances.

Look at the fastest SM Civics so far on the Tour this year. I see much more EP/CSP there than what's being proposed in this thread. And I KNOW they will get MUCH faster VERY soon.

But anyways, regardless... isnt this the beauty of SM? So many possibilities for creativity?

Keep it going. </TD></TR></TABLE>

CSP is as fast as SS, which is roughly where SM is *now*. It's still a new class, and nobody has fully developed a car yet. Sias' M3 was the first real attempt at a REAL SM car, and when it first came out, other than Tunnell, it ran away from everyone. I don't think you're destroying advantages when you're meeting weight minimum (which only this year anyone is actually doing, with Chris S. and Jason T., Neal was close...Chris Travis at least 'was' pretty far over). I don't want to build a car that can compete today, I want to build a car that can win in 5 years if the rules stay the same.

The fastest SM Civics so far on the Tour this year aren't capable of winning Nationally IMO. Daddio's EVO, Tunnell's and Sias' M3's will destroy them. Trophying isn't the same as winning when the margin is big.

You can win "National events" in underprepped cars, but it doesn't make those cars competitive. It means the competition wasn't there.

 

Just because the drivetrain is unlimited, doesnt mean you have to hang a turbocharged boat anchor over the front wheels and then figure out a way how to best drag race between gates It's the old compromise thing again. The way i see it, is you pick the lightest drivetrain and then use the unlimited mod allowance to squeeze as much useable power out of it as you can.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">You're gonna reach a point where you simply NEED power and NEED to put it down to overcome cars with 3x as much power that aren't THAT much lighter. You're gonna need to get out of the hole in 2nd gear "nearly" as quick as an EVO or M3. A regular CSP car isn't gonna do this. Even with more power...IMO. It's also not going to be able to run anything bigger than a 13 x _ without some rethinking on how to keep the rideheight low enough.</TD></TR></TABLE>

Again, all i'm saying is that you have to concentrate on what your car does best and minimize it's weak points, BUT WITHOUT hurting it's strengths too much. The M3s and EVOs strong points are that they can make BIG power AND put it down. Their weakness is weight and size. They can overcome some of that by running bigass tires (while at the same time improving on their strength) while still keeping the width and CG reasonable. At the extreme they "could" run 335-35-17s but they dont, as that would make them maybe a tad too wide and too high and like i said make the weakness worse.

Gotta think opposite with a small FWD car. Your strength is momentum and transitions. Work on THAT above all else within the constraints of what i said earlier. Light drivetrain set low, keep knocking down that weight and move it inboard. Make the minimum amount of compromise necessary to put the power down. How much power can say a n/a dseries make? say 200whp? Shouldnt need to compromise TOO much to put that down.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">CSP is as fast as SS, which is roughly where SM is *now*. It's still a new class, and nobody has fully developed a car yet. Sias' M3 was the first real attempt at a REAL SM car, and when it first came out, other than Tunnell, it ran away from everyone. I don't think you're destroying advantages when you're meeting weight minimum (which only this year anyone is actually doing, with Chris S. and Jason T., Neal was close...Chris Travis at least 'was' pretty far over). I don't want to build a car that can compete today, I want to build a car that can win in 5 years if the rules stay the same.

The fastest SM Civics so far on the Tour this year aren't capable of winning Nationally IMO. Daddio's EVO, Tunnell's and Sias' M3's will destroy them. Trophying isn't the same as winning when the margin is big.

You can win "National events" in underprepped cars, but it doesn't make those cars competitive. It means the competition wasn't there.</TD></TR></TABLE>

Agreed, mostly... However Chris was "only" about .5 sec behind Daddio on day2 at Toledo, so there's hope there... I'd love to make extrapolations based on how much faster Chris S. and Jason S. was over Nelson and the other Chris and try to predict how close it would be to Tunnel, Sias, Daddio and Co. Very tempting, but of course those things never work out like that. We just have to wait and see for Topeka. I'm sure the Civics are not close enough yet. But getting there... Or maybe the other guys got so much faster and will whoop on FWDs again. Then i'll shut up and start writing letters to SCCA for an SM split...

 

Some people on this thread are spending too much timing thinking about the cars as static objects, or only pulling G's in one direction.

Autocross is all about turning. You want the car to be as nimble as possible while still being controllable. The biggest advantage of FWD in this circumstance is that it is going to "pull" the car around the course, so use that to your advantage. Make the car have the lowest polar moment of inertia you can(all the mass down low and in the center). Make the car very tail happy with a lot of front end grip and use the the power to keep the car pointed straight(most FWD racers tend to know this is the best way to setup the car).

Moving weight out towards the edges of the car will only make it sluggish on turning in, and make you pull LESS lateral G's for the same tire grip. If you think about it, it takes a force from the tire to rotate the car to its initial slip angle and keep it in a corner. The farther out from the center the mass is, the more force it will take just to get the optimal slip angle on all your tires. You might still corner steady state at around the same lateral G's, but you're going to spend a lot of time in transition on an autox course, so you can't afford to lose any lateral G's.

I think you guys are also severely underestimating the amount of power you'll need to run with the BMWs and whatnot that are now showing up. A FWD car is going to struggle to put it down, but a near stock K series, even in a 1800lb car isn't going to keep up with the top guys once you get into 2nd gear. All the Nissan guys going for SM now are looking at SR20's putting out about 350rwhp - so I suggest you start thinking upwards of 250-300whp.

I'd honestly look towards a small turbo setup personally, but Honda guys can't size a turbo for anything but dragracing it seems like. You'd need a small turbine housing to get punchy response in the midrange and deal with the ~5-10whp hit up top - which shouldn't be an issue if you actually run enough boost.

I don't think an NA car is going to make enough pull in the midrange to compete with the SC'd M3 guys, or even the guys with 3.2L S54's that are still putting out 260-270 ft-lbs of TQ to the wheels.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jsi &raquo;</TD></TR><TR><TD CLASS="quote">
Gotta think opposite with a small FWD car. Your strength is momentum and transitions. </TD></TR></TABLE>

This is my concern as well. Maybe I am stuck in a rut here, but I can't help looking at past results and in doing so I think about the Thomas/Lombardo EP Civic. That car is the transitioningest SOB I ever saw. 02' Natz had that 7 cone slalom on the south course... JT's car looked like a scared cockroach through there. Nothing else even came close and his times reflected it. If it weren't for a lousy cone right at the finish his time would have been even more stupid-fast than it already was. However that same car is quite unimpressive in the power department. His launches were almost painfully slow.

His times completely eclipse any SM car ever built. The thing is, I don't believe that huge time gap can be attributed solely to slicks an -180ish lbs. Maybe a second or two, but he ain't beating SM by 2 seconds. While JT is "the man", I also think some of the new crop of SM drivers are in his league in terms of FWD talent. And, the J/L car has seen more development than most of the fast SM cars put together, so I wonder if that warrents a look at taking a more traditional approach.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jsi &raquo;</TD></TR><TR><TD CLASS="quote">

Just because the drivetrain is unlimited, doesnt mean you have to hang a turbocharged boat anchor over the front wheels and then figure out a way how to best drag race between gates It's the old compromise thing again. The way i see it, is you pick the lightest drivetrain and then use the unlimited mod allowance to squeeze as much useable power out of it as you can.</TD></TR></TABLE>

Your version of useable power seems to be different than mine. I think you can *use* at least 300 whp. I think you should build the car so it can spin the tires, as jzr said, at 65 mph in a straight line, on a good surface. A built D series, ala Jason or Chris S's attempts will not do this. Also, AFAIK, neither has TC, although Jason has a launch step limiter.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Again, all i'm saying is that you have to concentrate on what your car does best and minimize it's weak points, BUT WITHOUT hurting it's strengths too much. The M3s and EVOs strong points are that they can make BIG power AND put it down. Their weakness is weight and size. They can overcome some of that by running bigass tires (while at the same time improving on their strength) while still keeping the width and CG reasonable. At the extreme they "could" run 335-35-17s but they dont, as that would make them maybe a tad too wide and too high and like i said make the weakness worse.

Gotta think opposite with a small FWD car. Your strength is momentum and transitions. Work on THAT above all else within the constraints of what i said earlier. Light drivetrain set low, keep knocking down that weight and move it inboard. Make the minimum amount of compromise necessary to put the power down. How much power can say a n/a dseries make? say 200whp? Shouldnt need to compromise TOO much to put that down.</TD></TR></TABLE>

If the M3 has 285/315s on it and weighs 2500 lbs, and I have 285/225s on my 1800 lb car that is narrower and lower, I don't think I'm giving up ANY of my advantage right off the bat. It's still gonna handle as well as an 1800 lb CSP Civic, if not better. It wouldn't be giving up anything over the current crop of SM FWD cars, it would just be allowing them to do the things they currently cannot do, better.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Agreed, mostly... However Chris was "only" about .5 sec behind Daddio on day2 at Toledo, so there's hope there... I'd love to make extrapolations based on how much faster Chris S. and Jason S. was over Nelson and the other Chris and try to predict how close it would be to Tunnel, Sias, Daddio and Co. Very tempting, but of course those things never work out like that. We just have to wait and see for Topeka. I'm sure the Civics are not close enough yet. But getting there... Or maybe the other guys got so much faster and will whoop on FWDs again. Then i'll shut up and start writing letters to SCCA for an SM split... </TD></TR></TABLE>

Chris has had 3-4 years of building EF Civics. So does Jason. And Toledo seems to be an oddball event anyway.

As another way to look at it...instead of CSP and EP... look at DM. They all have the SAME weight limit, yet a FWD runs right near the top and almost won this past year.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 &raquo;</TD></TR><TR><TD CLASS="quote">This is my concern as well. Maybe I am stuck in a rut here, but I can't help looking at past results and in doing so I think about the Thomas/Lombardo EP Civic. ... so I wonder if that warrents a look at taking a more traditional approach.</TD></TR></TABLE>

That Lombardo Civic is my original inspiration for my SM Civic as well when i was starting out in autox. My original plan was an 84-87 Civic too, but i figured the better suspension on the EF would be ahead given both have to run at the same weight, eventhough it would take more work to get it down to min. weight. I wonder how much of the EP allowances were really used on the Lombardo car. I mean tubing the front while actually relocating the suspension points for example. And AFAIK, the thing was only making like 140whp, if that. And it was just plain destroying anything out there with closed wheels.

Damn, i wish John and Tom were on here to give some input.