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Building a Racer to beat a Honda CRX - Options?
Wouldn't I need a camber it to that?
I can see your point on the tire temps, good to know.
The comment about the lessons, I meant regarding CG, balancing the plane and balancing the car.
Brian Haygood <haygood@myway.com> wrote:
Try a cheap harbor freight pyrometer some time. Measure each tire's outer, middle and inner temps imediately after the lap. If the outers are higher than the middles, add air. If the outside is hotter than the inside, change camber. Dirt simple, really. The nice thing is that it gives you a good feel for the average workload on the tire, not just the maximum like chalk will. Tire manufacturing guys will tell you that the inside should be a bit warmer than the outside - how much is hard to nail down.
Not sure about the flying comment. Becoming an engineer is mroe helpful here. I might be flyin to Kankakee (sp?) some time in the next few months.
BH
--- On Tue 01/23, Tonee Northam < pb3vr6@yahoo.com > wrote:
From: Tonee Northam [mailto: pb3vr6@yahoo.com]
To: haygood@myway.com
Date: Tue, 23 Jan 2007 15:09:56 -0800 (PST)
Subject: Re: Building a Racer to beat a Honda CRX - Options?
Learning to fly really has paid off hasn't it?
I don't use a pyro meter but I adjust my tire pressure after ever run and use chalk on the side walls to see when or if I need to add/remove air.
Brian Haygood wrote:
Yes, everyone is on track with the power mods. How about suspension? What class are we talking about here?
Things that come to mind (from a guy who hasn't really competed hard in a Scirocco, but I've prepped other types for race):
Use the lightest wheels you can afford with the best tires you can afford
Lower the snot out of it, do whatever strut tower or strut mods you can to give you more compression (bump) travel, then choose springs that will keep you from bottoming out anywhere on the track. Use sway bars to stiffen
further and to adjust over/understeer balance to your liking.
Lighten it well beyond what the class minimum weight restriction is by cutting things off mercilessly. Add steel or lead to the car to bring it back up to weight. Removing steel all over the car and then putting the weight back where you want it is the idea. Centralize the weight and lower it as much as possible. Mount the weights below the car at or near the C.G.
Note: I once saw a car with barbell ends welded in to the corners of the trunk so he could adjust weight balance front to rear and left to right to balance the car. This is a lousy idea. Mount the weight under the car instead of inside the trunk to lower C.G. Centralize the weight close to the C.G. - the balancing he was doing is better achieved with suspension height adjustments (i.e. coilovers or shims under springs).
Get an infrared pyrometer and measure tire temps after every run and use them to set
your camber and tire pressures. This is easy to do, but was hardly done by anyone when I was Autox'ing.
BH
--- On Tue 01/23, =?iso-8859-1?Q?Jeff_Toomasson?= < area53@validpath.com > wrote:
From: =?iso-8859-1?Q?Jeff_Toomasson?= [mailto: area53@validpath.com]
To: Cory_Langford@bcit.ca
Cc: scirocco-l@scirocco.org
Date: Tue, 23 Jan 2007 15:05:52 -0600 (CST)
Subject: Re: Building a Racer to beat a Honda CRX - Options?
To trot out an old phrase - "speed costs money; how fast do you want to go?"
Also, I guess you need to define "legal" mods - ie, does massaging the engine
count as legal?
If so, my recommendation would be to get a hold of a Heron head and pistons.
P&P the snot out of the head (an expert job is required here) and get some 7mm-
stem big valves (41mm in/38mm out). Lighten/knife an early 1.7 crank,
lighten/balance the lower
internals and run a Supersprint race exhaust w/
whatever cam you can get away with. Dual 40mm carbs are a must if allowed and
the usual race suspension treatments still apply. If carbs aren't allowed, get
Euro CIS to remain stealth and use the traditional methods to minimize airflow
restrictions. You should be able to wring out 115+ hp if tuned right. A cam
gear will help emphasize the torque band if you prefer.
The true gap-closer will be how you choose to gear it though. You could run a
4.25 R&P for a
really close box or roll w/ a 2Y or 4K.
HTH, JT
> After doing some nosing around, it seems the class that a mk1 (or mk2) roc
> would end up in at the local track is dominated by 90s Honda CRX's with
> the
1.5L 16V engines.
>
> They seem to be putting out about 108-110 HP with legal mods and weigh in
> around 2000 Lbs. Internet lists the torque from the factory at 90 Ft-lbs
> at
4500 RPM.
>
> The local track is short and full of corners. It is far from a high speed
> track, there is only one real straight section and it is not that long.
> So
a quick point and shoot style setup seems to be the way to go.
>
> I figured a high torque car would be better than a masive HP beast. So
> the
question remains, can a Roc be designed to out class the 0.06 HP/Lbs
> crx?
> Class is limited to 1750cc, so the 1.7L from a mk1 or early mk2 works
> great. BUT: the 75HP it comes with stock might get bumped to
80 with
> legal
mods (still invstigating) and the curb weight for a mk1 roc is
> around 2000
Lbs as well is it not?
>
> That puts the roc at only 0.04 HP/Lbs, what I am hoping for is to get a
> whole lot more torque out of the engine to pull out of the corners.
> Just looking for ideas :)
>
>
Cory
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