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curtis73
curtis73 HalfDork
12/3/10 3:08 p.m.

If a guy had a road-race car, what might be some of the engineering differences between a car set up to run at Laguna Seca versus one set up to run one of those timed mountain climbing events?

Long story short... I'm building a road race/street vehicle with the intention of getting into occasional amateur/fun road racing, and the idea of mountain climbing is appealing to me as well.

Seems like the two should be relatively similar. Maybe slightly less braking requirement and more cooling for the mountain?

ReverendDexter
ReverendDexter SuperDork
12/3/10 3:17 p.m.

I would expect that a hill climb car is going to need a little more compliant suspension. Not all the way rally-style, but something that can soak up the bumps of ignored pavement and high enough that it won't cause you to impale your oil pan if you happen to have to straddle a rock the size of a golf ball.

I think you're spot on with the braking, though if there's any downhill sections in the hill-climb, you'll need all the brakes you can get.

I also expect that speeds would be slightly closer to autocross, so if you have an aero mods, I'd have them tuned for as much grip as possible, and not worry so much about any extra drag.

And to add fuel to the fire, one of my favorite Mustang vids on youtube: GR40 '98 Cobra Virginia City Hillclimb - Youtube

BoxheadTim
BoxheadTim Dork
12/3/10 3:21 p.m.

Are we talking tarmac hill climbs or ones that run partially on dirt roads (like Pike's Peak at least used to be run?).

I don't think there's much of a difference if you run on tarmac, although you might want a little more ground clearance depending on the state of the road.

DeadSkunk
DeadSkunk HalfDork
12/3/10 3:35 p.m.

Neat video, but I couldn't help but visualize Mrs. Potato Head.

Ian F
Ian F Dork
12/3/10 3:58 p.m.

There are a number of old road-racing cars that run PA Hillclimb events. Old IT cars... Spec Miatas... and a surprising number of open wheel cars (Swifts, Formal Fords, V's, etc). Having seen most of the courses, a slightly taller ride height and softer would be recommended.

racerdave600
racerdave600 HalfDork
12/3/10 5:15 p.m.

I ran my ITA car at a hillclimb and it did quite well. If it's tarmac not sure you have to do much to it. if you can change gearing there might be some gain there. Possibly a spring rate change, but at least the ones I went to the surface wasn't too bad.

z31maniac
z31maniac SuperDork
12/3/10 6:24 p.m.

That video frightened me. I can't imagine doing a hill climb in anything less than a fully caged vehicle.

DavidinDurango
DavidinDurango New Reader
12/3/10 6:34 p.m.

1) The driver will need larger attachements.

2) a little boost never hurts, but then increase #1.

Don't ask me how I know . . . . .

( "If you go off there you'll never stop rolling . . . " )

http://www.nhahillclimb.org/

curtis73
curtis73 HalfDork
12/4/10 12:26 a.m.
BoxheadTim wrote: Are we talking tarmac hill climbs or ones that run partially on dirt roads (like Pike's Peak at least used to be run?).

I would probably stick to tarmac stuff. At this point I'm such an amateur racer in terms of skill and experience that there is no point in adding that much complexity to the car and my learning curve (no pun intended). This would be for my entertainment. At least at this point, I'm not wanting to "make it in racing" or compete for points and money. You know the fun you and your buddies have going to race go-karts? I just want to do that with a 700-hp car.

Kinda like getting into boxing as a hobby. I don't need to train hard or earn titles, sometimes its just fun to legally punch someone in the face under the guise of fitness. Same thing. I want to be able to drive my car like its designed to be driven at its limits (and my limits) without killing anyone or getting a ticket, all the while learning and having fun.

curtis73
curtis73 HalfDork
12/4/10 12:39 a.m.
I would expect that a hill climb car is going to need a little more compliant suspension. Not all the way rally-style, but something that can soak up the bumps of ignored pavement and high enough that it won't cause you to impale your oil pan if you happen to have to straddle a rock the size of a golf ball.

The chassis I'm planning is designed to be a street chassis that is capable of 1+ G's when dialed in for race, so I think the overall package should be capable of absorbing the neglected roads and be tunable for anything from performance street all the way up to more potential than I'm currently capable of fully utilizing

Having seen most of the courses, a slightly taller ride height and softer would be recommended.

I'd like to see more about this. The plans include double adjustable coilovers so it can be tuned as necessary. Do you think it needs more ride height than (for instance) a stock vehicle that has been lowered with aftermarket springs?

Jensenman
Jensenman SuperDork
12/4/10 8:30 a.m.

I've seen lots of IT cars at hillclimbs, while not generally real fast (due to the basically stock engines) they seem to work well.

About suspension, there is no 'one size fits all' answer, the hillclimbs I have done are no rougher than the average autocross but the top speeds are good bit higher and that to me dictates a stiffer setup than a street car. The Abomination's autocross settings worked just fine, I left the 5" ride height alone. But keep in mind that car's suspension has little or no relation to a street car; it has motorcycle coilover shocks all around, for instance. It's possible to get airborne, so if something expensive hangs down low you might want to consider a skidplate, etc.

Boost (or at least fuel injection) is a good idea, if the course rises, say, 750 feet carburetors can't cope and the engine runs like crap the closer you get to the top. The Abomination's Dellorto on the 12A would run noticeably richer at the top of the hill than at the start. That's one reason the Jensenator has fuel injection. So if you haven't bought a car yet, you might want to narrow your search to FI and possibly boost.

More cooling will be needed. The engine will be working hard the whole way, this generates extra heat which has to go somewhere. Again speaking of the Abomination, with a stock RX7 radiator the coolant temps ran about 10-15 degrees higher than at AXes but still below the 'uh oh' range. That's why the Jensenator has an enormous double pass aluminum radiator.

DWNSHFT
DWNSHFT Reader
12/4/10 9:21 a.m.

Compared to track events, a hillclimb has lower speeds so you'd like lower gearing. Maybe a defroster, too.

David

iceracer
iceracer Dork
12/4/10 9:34 a.m.

True, you don't need much braking on the way up but you will need them on the way down. Somtimes the way down is faster than the way up.

Giant Purple Snorklewacker
Giant Purple Snorklewacker SuperDork
12/4/10 9:57 a.m.

I have some NY acquaintances who have been very successful in the Targa Newfoundland. The cars all run much higher clearance and softer spring rates than you would use at the Glen or Summit Point. I can't speak to Laguna except to say I know people who come from there to the NE to race and bitch about how bumpy our tracks are. They set up really stiff for glass smooth racing out west and find they can't make it work here. So - if that is what you are used to - think waaaaay softer.

I would imagine excellent damping is key to good times. Bumps, mixed surfaces and so on. Individual adjustment for slow/fast on both rebound and compression at the least.

Since you don't get to do umpteen laps on a hillclimb to be able to learn the track in your sleep - an ability to accelerate quickly and recover mistakes would take precedence over a fast momentum car or a wicked fast but twitchy ride IMO. Choose a setup leaning more toward rear traction exiting a turn to put more power to the ground and big tire/grip to brake late and keep as much as you can for the next one. If it wasn't so bumpy I'd suggest a live axle 5 link - but there is a reason all the top rally cars are AWD. They CLAW out of corners on E36 M3 roads.

EDIT: Disclaimer... I've never run a hillclimb or road rally so this is just bench racing. Everything I do is based on east coast road course experience.

StevenFV19
StevenFV19 Reader
12/4/10 10:40 a.m.
BoxheadTim wrote:

At this point I'm such an amateur racer in terms of skill and experience .... I just want to do that with a 700-hp car.

Umm.....Those two don't mix....

Steven

Tom Suddard
Tom Suddard SonDork
12/4/10 10:50 a.m.

Population control at its finest.

curtis73
curtis73 HalfDork
12/4/10 11:19 a.m.
Umm.....Those two don't mix.... Steven

I've drag raced 1500 hp and had a few 500-600 hp street cars before, just never had the experience of going fender-to-fender before.

BoxheadTim
BoxheadTim Dork
12/4/10 12:20 p.m.
z31maniac wrote: That video frightened me. I can't imagine doing a hill climb in anything less than a fully caged vehicle.

I've actually been up that road at slightly more legal speeds. There are something "interesting" tire marks on that road . Believe it or not, this is the easier road up to Virginia City.

I'd love to take part in it but I'm not sure if they'll let me in with a reasonably mundane vehicle as it's organised by the Ferrari club.

StevenFV19
StevenFV19 Reader
12/4/10 4:25 p.m.
curtis73 wrote: I've drag raced 1500 hp and had a few 500-600 hp street cars before, just never had the experience of going fender-to-fender before.

Before you're sliding backwards into a wall... If you have the money to built/buy that much horsepower get an IT car or FV then work your way up. Drag racing and having a street car is pretty incomparable to road racing.

Good Luck, Steven

curtis73
curtis73 HalfDork
12/4/10 7:12 p.m.
StevenFV19 wrote:
curtis73 wrote: I've drag raced 1500 hp and had a few 500-600 hp street cars before, just never had the experience of going fender-to-fender before.
Before you're sliding backwards into a wall... If you have the money to built/buy that much horsepower get an IT car or FV then work your way up. Drag racing and having a street car is pretty incomparable to road racing. Good Luck, Steven

Not sure what your intention is in this post ? I may be just reading it the wrong way.

Never said I owned a 1500 hp car, but in my type of hobby (hotrodding) building 700 hp isn't that expensive. When you start with a $50 500ci engine from a 76 caddy its not hard

Your type of experience is exactly what I need. I know very little about racing. I do have a great deal of experience with building and driving very high performance cars. I'm not rich... I don't own these cars. I worked at a hotrod shop where I built and designed these type of cars. I would just like to translate my desire to USE a high performance car as it was designed to be used in a controlled, legal, safer environment instead of on the street where I'll kill people and go to jail.

Y'all should be proud of me

StevenFV19
StevenFV19 Reader
12/4/10 9:35 p.m.

I just don't want you to go out there and tear up a car you built by yourself. Especially after all the designing and engineering, then after pushing through the teething problems, it would be depressing. It'd be nice if you could built a car and modify the ECU to the power that you want so you can add/subtract more power as you go. Much like the Jim Russell open wheel cars--> right here . I wish I had the skills to build my own car like that. I really wanna take a welding class. If you are building your own frame, and you go with a fiberglass body, your car should do well above 1g. Good job keeping this off the street . Good luck with it, sounds like an awesome project.

Steven

curtis73
curtis73 HalfDork
12/5/10 2:33 a.m.

Thanks. I think I've been viewing this project as a car that I plan to build to be torn up (if that makes sense). So far the driveline I've spec'd out should be divine overkill - designed to take absolute abuse and be able to dust itself off. The only exception is the transmission - the T56 I had built should be bulletproof to about 600-700 lb-ft. We'll find out when I put an 8.8L stroker in front of it

I've done a few chassis myself before, but they were designed for 50's mercs and the point was to be streetable, accept common bolt-on modern parts, and generally not suck They excelled at very little other than making a safe platform that accepts modern parts for drivability and safety, but in truth, most rodders who are building a 51 merc with suede paint and air ride are more interested in looking good at the cruise-in than they are performance.

I think I'll let the pros build my chassis. I've been talking with Mike at Schwartz about tweaking their A-body chassis for what I'm planning. That way I can stick to my strong point which is driveline engineering.

I'm actually looking forward to battle scars... on the car, not me. I'm not going big money on a pro-touring car with flawless body work and hand-stitched heated seats. Fortunately the body is very straight, so a pint of bondo and I'll fog it myself to get it looking sexy. Shaking hands with a wall or rubbing a competitor is part of the game and I'm ready for it. (hence one of the reasons I'm building a LeMans and not a GTO)

Like I had said before, I'm not in this to get trophies or be serious about winning and squashing the competition. I'm talking about a weekend game of touch football, not the NFL. I know everyone here has felt it before. If any one of us here were handed the keys to an F40, we wouldn't feel satisfied taking a sunday drive while obeying the speed limit, we would long for a space to stretch her legs without going to jail for it. I just get chubbed up at the thought of really high performance vehicles and I would like to use amateur racing as an outlet for being able to use the car as it was designed.

sachilles
sachilles Dork
12/5/10 9:45 a.m.

Hillclimbs vary regionally. So the key to success with one organization, is not necessarily the key to success with others.

Some things to think about. The cage requirement are something worth thinking about. I'd recommend a cage intended for rally use. I highly recommend that you have a flemke(or some call it the fia bar) bar. Basically, in addition to the a pillar bar, you put a straight bar from the top of the windshield to the floor plate of the a pillar. It's important for many reasons, but exceptionally useful when you hit a tree. Suspension will vary based on the hill, but in general you'll probably go softer than road racing. Brakes, not as important as road racing. You'll want a pad that heats up a touch quicker. Tires, you'll want some thing that warms up quicker here as well. Longevity isn't a huge concern. Transmission, a standing start is the norm at the hillclimbs, so make sure your transmission/clutch can handle this abuse.

In general if you prepare like a tarmac rally, you'd be in good shape.

2002maniac
2002maniac HalfDork
12/5/10 10:22 a.m.

This thread reminds me of "love the beast." great movie about eric bana's ford falcon that he has built up for tarmac rally. I think an amateur racer (drag only?) In a 700 hp car at 2 hillclimb is a recipe for a spectacular crash. Make sure you have a stout rollcage and keep your gopro rolling.

AngryCorvair
AngryCorvair SuperDork
12/5/10 12:47 p.m.
curtis73 wrote: Kinda like getting into boxing as a hobby. I don't need to train hard or earn titles, sometimes its just fun to legally punch someone in the face under the guise of fitness.

Say What?!

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