Importance of Weight for Rallying

New to the forum but have lurked for ages. Hi everyone!

I'm thinking of picking up a cheap rallycross beater next year and am hung up on whether to go for a heavier higher power car, or a lower power lighter car.
My first car was a 944 and I'd like to eventually go back to one and make one a rallycross rat but money wouldn't allow for it for some time.
For the time being I'm looking at Hondas. I'm not particularly a fan but I've only ever owned german cars and having something easier to maintain and beat on sounds appealing.

Specifically I'm looking at Fifth gen base model civics  - around 2350 lb curb weight | D16Y7 making a little above 105hp
Fifth gen preludes - nearly 3000 lb curb weight | H22A4 making a little below 200hp

Nice condition base model civics and beat-up preludes can both be had for under 2 grand CAD around me it looks like.
On paper the prelude looks better to me due to the power difference, but I've never rallycrossed or done any performance driving.

If I bought either one it would be made a bit lighter by doing an interior strip, but I wouldn't plan on doing a lightweight battery, lexan windows, etc. Just taking out what is currently there.

Which do you think would make for a better rallycross platform?

Weight for "rally" and for rallycross are two different animals. For stage rally, the car is going to be relatively heavy regardless, seeing as it's going to be caged, has two people in it, and at very least a spare tire, jack, and some other gear. Plus a rally car has to be street-legal, so it has to have full lighting, catalytic converter, and other things that make it legal to drive on public roads.

For rallycross, all bets are off if you run in modified. One of the fastest MR guys in the country is Vaughn Micchie, who runs a Porsche 924S. His car is "lightweighted" to the extreme....all lexan, zero interior except a seat, no lights, fiberglass panels, and more. Unless you go to that extreme, a 924/944 is marginally competitive in a fast region. Dan Gugger runs a 944 in our region (MR) and though the car isn't heavily modified, he's quite a ways off the pace at the moment (though he'll get faster for sure). In slippery conditions, the 944 is great though, since it has more weight over he drive wheels than most other RWD cars out there. But if you know German cars, the "easy button" for rallycross for cheap is an e36 325i/328i. Our event last weekend in a highly-competitive MR class went 1-2 to e36s (granted, one was an m3), and the 328i that was 2nd is almost stock, agaisnt a class full of heavily built e30s, Miatas, BRZ, etc. A stock e36 for $2-3k will be compeititive right out of the box. As will a Miata. And I'm saying that as someone who owns a 924S and rallies an e30 (and daily-drove a WRX for a decade). I honestly would say that there is no way, no how my 924S would be faster than an e30 in most rallycross conditions, aside from going extreme like Vaughn has. Just my opinion though. I know a couple guys who stage rally 944s as well. 

Can't speak much to Hondas since I don't know them well. FWD classes have a lot of competitive cars - anything from Civics to Focuses to Fiestas to Elantras and plenty of others. I will say, from 8-9 years of rallycross experience, that the FWD cars don't seem to be any more "relaible" than the older RWD cars - very few e30s or Miatas or e36s DNF locally, but we see plenty of FWD cars popping axles and stuff like that. May just be the drivers, IDK. But any car driven with mechanical sympathy will do fine. If you do stupid stuff, you'll break stuff. 

I can't see I've ever seen a Prelude out at any of our large events, though plenty of Civics. Civic Si is the ticket, really. 

For rallycross, lighter is generlaly better. Look at results - Miatas are very competitive, e30s (which are pretty light), and similar. Ralycross requires good car balance and quickness more than all-out power. Long wheelbase = less maneuverable in general. Weight balance matters too since you want traction. 

What region do you plan to run in?

In reply to irish44j :

I'm planning to run here in Ontario with the Kitchener-Waterloo rally club. They do rallycross, I haven't participated yet but based on the website the only classes seem to be 2wd, 4wd NA and 4wd turbo/supercharged. From youtube it looks like people have run stuff from a 1973 for capri to modded STI's. Should be good fun.

I didn't realize RWD could be so competitive, thanks for that insight. I would maybe consider an e36 then. OBD1 325's can be had for pretty cheap here. I had only really been considering Honda's for ease of maintenance. I would much prefer to run an e36 since I really like the chassis, a buddy has a 318ti and even though it's an automatic it's still a riot.
My only concern with running an e36 is I've heard that you need to reinforce just about every piece of the suspension.

Do you have pictures of your 924 anywhere? I love them so damn much but I won't be in a financial position to go after one again for quite a few years

irish44j said:

 

For rallycross, lighter is generlaly better. Look at results - Miatas are very competitive, e30s (which are pretty light), and similar. Ralycross requires good car balance and quickness more than all-out power. Long wheelbase = less maneuverable in general. Weight balance matters too since you want traction. 

 

That is generally true but can also be region/course specific.  In ETR there is a 4th gen z28 camaro that averages top 3 FOD in RAW times and is usually 2nd behind a 2.5RSTi running in MA while the camaro is in SR. The camaro is on average 30-45 seconds faster than the MR miatas at the end of the day.

this is the fastest RWD car in ETR 

For rallycross it's definitely course specific.  Regions that tend to build tighter courses will favor shorter, lighter cars more. 

I'm a fan of lexan and protective film for rally cross. Where the weight is, in terms of center of gravity and balance, matters almost as much as power to weight. Left foot braking makes having some weight to transfer forward and back a good thing, especially in a FWD application. Availability of a limited slip, wheelbase and overhang matters more than actually mass with a FWD car imho. 

In reply to captdownshift :

Are welded diffs useful in rallying, if a LSD is too expensive?

Given a certain power/weight, the light car will have better transition and braking behavior. The more powerful car will have an advantage once aero drag starts to come in to play. 

BrapBrap said:

In reply to captdownshift :

Are welded diffs useful in rallying, if a LSD is too expensive?

Rally is completely different from rallycross.  The objectives are different and the positive characteristics are different.

Please keep that in mind.

In rallycross, car control and predictability is the most important thing, and in many cases a limited slip will hinder this greatly.  In other cases a car may be undrivable without one.  (Lightweight front driver?  Limited slip means you can't turn, negating the advantage of having a light front driver.  Heavy powerful rear driver?  No limited slip means you can't predictably exit corners, negating the advantage of having power and rear drive)

In reply to Knurled. :

Perfect summation. Thank you 

Hey Neighbor! I'm just over in Kitchener and have been running the KWRC rallycrosses the last two years with the club. Our course isn't too rough, I personally run my daily driver legacy wagon on snow tires and haven't broken anything yet. Lightweight is always going to be better on our course but as a guy in one of the heavier cars I'm still very competitive in my category and overall, ultimately the driver will make more of a difference. We don't separate out our 2wd cars so the rwd and fwd cars all run against each other and that is the category that sees the most entries. Overall the fwd cars do better but our first event this year was won by an RX8 and we have had an E36 win in the past. If the course is dry rwd is very competitive but if it is wet our clay is extremely slick and the fwd cars take over (and embarrass most of the 4wd cars). Over the past two seasons they have started watering the course to keep dust down so the slick conditions aren't unusual even if it is only a few runs that are like that over the day.

I've had my eye on this car for the past few months as it would make a great rallycross car (provided you aren't afraid to turn some wrenches and put it back together) - https://www.kijiji.ca/v-view-details.html?adId=1408356639&siteLocale=en_CA&requestSource=b

Whats your daily driver? it may be enough to start out with. Pay attention to our registration as the entries fill up in under a week now as our races are so popular. Maple Leaf Rally Club also runs events near Bancroft but are looking at doing one at Markham fairgrounds in July.  The course and events that PMSC Rallycross do are also supposed to be a lot of fun near Peterborough.

This Thursday is our monthly meeting at the Allen Reuter Centre at 7:30 pm, I won't make it but you don't have to be a member to show up. Matt Tregunno heads up the Rallycross stuff and will likely be there.

Adam

MrChaos said:

irish44j said:

 

For rallycross, lighter is generlaly better. Look at results - Miatas are very competitive, e30s (which are pretty light), and similar. Ralycross requires good car balance and quickness more than all-out power. Long wheelbase = less maneuverable in general. Weight balance matters too since you want traction. 

 

That is generally true but can also be region/course specific.  In ETR there is a 4th gen z28 camaro that averages top 3 FOD in RAW times and is usually 2nd behind a 2.5RSTi running in MA while the camaro is in SR. The camaro is on average 30-45 seconds faster than the MR miatas at the end of the day.

true, but our courses are also very wide-open. No, Miatas in MR aren't very competitive since we're full of M50-swapped e30s and e36 and we have a hilly venue. But "overall" Miatas do well nationally on the majority of rallycross courses out there. Yeah, there are outliers like your venue and our venue that favor more powerful cars.

I still want your Z28 friend to come play up at Panthera with us. IDK what the competition looks like in ETR, but DC it is our largest and most competitive class. If he can beat everyone here, he can beat almost everyone anywhere in the US (IMO). 

Cars on a list don't mean much by themselves. We have an STI Type RA running locally. Pretty sure he had slower times last weekend than about a dozen old BMWs lol....

Keith Tanner said:

Given a certain power/weight, the light car will have better transition and braking behavior. The more powerful car will have an advantage once aero drag starts to come in to play. 

or, at venues with big hills. Panthera, where we run, has a pair of ~1000ft uphills, where power cars make up a ton of time. One of the main reasons I just engine-swapped my e30 lol....I could beat everyone on flat courses, but would lose by 10+ seconds in these hilly courses. 

Obviously, boosted Miata is the answer ;)

ETR is a RWD or AWD heavy region. There is 1 FWD car that runs with any consitant turnout. MR/SR/PR is composed of like 7-10 miatas, 1 z28, 1 sn95 and a volvo 240. Last event AWD had like 33 drivers with most being in MA with 15, PA with 10 and SA with 8. Also seeing alot of Audi A4's starting to show up. I dont have numbers for RWD classes but it was 5-6 miatas, the z28,the sn95 and an e36 ti. FWD was a mk2 golf and a tiberon.

MrChaos said:

ETR is a RWD or AWD heavy region. There is 1 FWD car that runs with any consitant turnout. MR/SR/PR is composed of like 7-10 miatas, 1 z28, 1 sn95 and a volvo 240. Last event AWD had like 33 drivers with most being in MA with 15, PA with 10 and SA with 8. Also seeing alot of Audi A4's starting to show up. I dont have numbers for RWD classes but it was 5-6 miatas, the z28,the sn95 and an e36 ti. FWD was a mk2 golf and a tiberon.

Our FWD classes are starting to grow a bit, but our season opener last week (IIRC) here was our RWD turnout:

MR (the M3 won, he's last year's class champ, the other e36 was 2nd, and like 7 e30s behind them. The BRZ was at the bottom)

PR (Shawn - moxnix here - won in the Miata, not surprisingly, Because he's fast as hell)

SR (the S2000 won - he's a multi-time SA champ in a GC Impreza, the S2k is his daily driver)

So yeah, close to 30 RWD cars....and only 16 Subarus :)

This is what our course looks like - though at this event we didn't use the two really big hills since they were too rutted up from the winter. So this is a "technical/slow" course for us

BrapBrap said:

In reply to irish44j :

 

Do you have pictures of your 924 anywhere? I love them so damn much but I won't be in a financial position to go after one again for quite a few years

I bought two of them for $1000 each a couple years ago - one with a good engine, one with a decent body, and put them together. I have a bunch about it in my e30/rally build thread in the build forum here. Here's a couple pics - it's a mostly-stock '87 924S with an '88 motor, with a tune and a few other upgrades.

at our rallycross venue when my e30 was out of commission (I competed in someone else's e30 though...)

In reply to adam525i :

Woah! Hey neighbour! I'm reporting in from north Waterloo... 

Thanks for all that information, very good stuff to know. Especially about registering early - I had no idea entries filled up, I wasn't sure if rallycross was all that popular. I will have to attend some of the meetings closer to when I'm ready to buy a car. 

I am strapped for cash atm, and will be for about a year, but after that I'd like to pick up a cheap car and run the kwrc events. My end game dream is to pick up a 944 and make a rallycross rat. Parts are expensive though and I'd prefer to learn the ropes on something that I don't care about breaking.

My daily driver '02 Jetta vr6 is a great little car but I'm about to roll over 400k and it's my only transportation besides a bus pass so I'm not ballsy enough to rallycross it, lol.

In reply to irish44j :

Beauty man, jealous. My 944 was an '86. It was a real piece of E36 M3 but I loved it. Really messed up on the purchase and pulled the trigger on the first one I saw, it was my first car and I was an idiot. Well still am, to a lesser degree. The floor was rotted and one day while it was on jack stands we heard a creek, my buddy got out from underneath as fast as he could, we waited, maybe 10 seconds later it crashes to the ground. The jack stand had now pierced right through the jack point and come up through the floor by the clutch pedal.

It had a myriad of other issues and I eventually learned someone had even rolled back the odometer at some point. But I loved it. When I eventually pick one up again I'm going for an early model, or a 924S.

In reply to irish44j :

this is apparently going to start showing up this year and will likely give MR and the z28 a run for its money. its apparently a 914-6 with a 3.3 in it.

irish44j said:

Keith Tanner said:

Given a certain power/weight, the light car will have better transition and braking behavior. The more powerful car will have an advantage once aero drag starts to come in to play. 

or, at venues with big hills. Panthera, where we run, has a pair of ~1000ft uphills, where power cars make up a ton of time. One of the main reasons I just engine-swapped my e30 lol....I could beat everyone on flat courses, but would lose by 10+ seconds in these hilly courses. 

Obviously, boosted Miata is the answer ;)

Hills shouldn't affect cars with the same power/weight any differently. It's engine power vs mass, and going uphill doesn't change the mass. Aero drag increases exponentially with speed and (in our over-simplified thought experiment) will affect all cars the same so power/drag overwelms power/weight.

In reply to Keith Tanner :

Oh, but it does matter a lot, since speeds are generally kept below 50ish MPH.  Straights are by necessity rather short.  A low powered car might not even be able to accelerate up a hill, while a higher powered car most certainly could, and the hill means it would also not need to waste much time slowing down again, as opposed to if it were a flat straight.

We used to have a venue with a significant hill, and even though the rest of the course was tight, it was very much a power venue.

I think a lot of this has been covered already but there's a few things happening. As everyone has correctly identified, rallycross courses are usually pretty low speed. Which means torque and gearing are more important than top end power unless the car is geared such that you can live at the top of first gear (which some hondas can make work out). I agree that on paper light weight would be better especially on tight courses but in reality it doesn't seem to be quite that simple. We just won the SR national championship on the tightest courses we've ever run on, in the second heaviest car in the class and not the best power/weight. And our main competitor who we'd never beaten before (but had never run against in this car) was in a car that's essentially an 8-9/10ths scale version of our car. So I think that weight distribution and ability to put power down are big factors, as well as driver skill. But even with that data I'm a little surprised the camaro mentioned above is as successful as it is so the equation might even be more complex than I just made it.

Anyway, for actual advice. our previous rallycross car was a 944 and it was actually pretty decent. The nice thing about it is that the chassis is designed around the car weighing close to 3000lbs, but you can pull a solid 400lbs or more out of the interior which then makes the chassis and suspension effectively more over-engineered which is good for reliability and longevity. Also I think we got a solid inch of extra ride height just from the weight reduction. So especially if you already have some knowledge of the chassis, I'd find a cheap one and run it, I don't think it would be too much more expensive than the hondas you're looking at and RWD is way more fun in the dirt.

Knurled. said:

In reply to Keith Tanner :

Oh, but it does matter a lot, since speeds are generally kept below 50ish MPH.  Straights are by necessity rather short.  A low powered car might not even be able to accelerate up a hill, while a higher powered car most certainly could, and the hill means it would also not need to waste much time slowing down again, as opposed to if it were a flat straight.

 

We used to have a venue with a significant hill, and even though the rest of the course was tight, it was very much a power venue.

The engine is working against the weight of the car. With less weight, there's less engine needed. Note that I keep going on about "the same power/weight". That's the key. A low powered car can definitely accelerate up a hill if it's not trying to drag a heavy body. If the power/weight is the same, then acceleration should be the same. I'm pretty sure the British trials drivers emphasize light weight over just about anything else, and they're always trying to climb muddy hills.

Acceleration in a straight line (before aero drag kicks in) is no different than acceleration up an inclined plane if you're working at the same power/weight.