The understeer cure

[Veriest1]

Thanks Nismo. That's pretty much what I thought you were saying. Obviously a modified suspension will probably be much more adjustable than the factory suspension and allow more options but, yeah, thanks a bunch.

Quote »The engines in those are amazing. SOHC KA24's that make like 300hp@10,500rpm. I waaaaant one.[/quote]Actually compared to most race car engines they're fairly cheap to build. You'd need race gas though and if you did all the work yourself you could probably stay under $4,000 fairly easily. If I remember correctly devious said a version could be done for around $3200-3500. Obviously to run on pump gas you'll have to have a lower comprehsion and would probably need the RPM's turned down a few notches to have something resembling reliability. It's quite doable and not much more than an SR or solid entry level KA-T setup. The DE is also an option with the ITB's and a Megasquirt or AEM. The DE should be a little more capable but it hasn't been fully explored as far as I know and it will be more expensive to build. There's quite a bit of info about them on here if you're really interested.

Edit: I assume getting well past 250 horsepower on pump gas will be nearly out the question so that's where the turbo options really start to shine in comparrison. Oh... and the idle will obviously be terrible if you run a full race cam. The guy I talked to at PDM said to keep a SOHC from dieing with their race cam the idle would need to be set between 1200 and 1500 RPMs.

[Dattebayo]

sticksion limit

Is that a real word? Good one. Im just messing with you. Get some sleep!

[Veriest1]

The engine does not get revved that high during the race. It would be highly highly unreliable.

Didn't know that. Where did you come up with said information? I just figured they rebuilt them every race or so.

What do they rev them to? And how long do they last under race conditions at that level?

[InsanityInc]

I find it incredibly ironic that you are argueing that camber doesn't "drastically" affect car balance, yet you claim a strut bar will change the attitude of the car.

You should read further into the strut bars purpose, you will find that it reduces dynamic camber loss by not allowing the strut towers to pull apart.

That's not all. It helps the front suspension geometry remain far more symmetrical in general. That's really the key part of it. Asymmetrical dynamic suspension geomtry obviously causes massive problems. It's not that your car's suspension is being made any better by the bar, it's just letting it work properly.

Quote »Understeer happens when the slip angle of the front exceeds the rear slip angle. The car does not have to exceed the tires sticksion limit in order to have an understeering situation.[/quote]Technically yes, but that sort of understeer can be easily corrected by just driving differently.

Quote »You can setup a car with 195's in the front and 375's in the rear to oversteer like it's on ice.

Tire sizing is meerly a guideline to go by, not the end all.[/quote]You missed the point. He was saying that improving the front suspension abilities = understeer, while improving the rear suspension abilities = oversteer, and I pointed out a pretty plain situation where that's blatantly wrong.

Quote »Sway bars don't increase rigidity. They have very little static rigidity due to the endlinks, they are built as torsional "springs".[/quote]Static rigidity doesn't really mean much when we're talking about driving a car. When they are under load acting as a torsional spring they also increase rigidity.

[Nismo_Freak]

Didn't know that. Where did you come up with said information? I just figured they rebuilt them every race or so.

What do they rev them to? And how long do they last under race conditions at that level?

Physics.

You don't magically sustain insanely high RPM in a KA24E just because it is in the GT3 class.

Even revving the engine out to 9000 RPM would hamper it's reliability due to the horrendous piston velocity.

Most SR's are ran only to 8500 - 9000 RPM in race cars.

Engines at that racing level are measured in hours.

[Nismo_Freak]

That's not all. It helps the front suspension geometry remain far more symmetrical in general. That's really the key part of it. Asymmetrical dynamic suspension geomtry obviously causes massive problems. It's not that your car's suspension is being made any better by the bar, it's just letting it work properly.

It does nothing to maintain symmetry in suspension.

Just by sitting in the car you are altering the symmetry of the suspension, unless you have properly counterweighted your vehicle and aligned it.

The only thing the bar does it prevent strut tower movement, and it's resulting camber change (and toe due to cambers affect).

Technically yes, but that sort of understeer can be easily corrected by just driving differently.

A properly setup car, is one that does what you want it to do naturally.

The driver should ideally never have to change their driving style to accomodate for such a simple error in setup.

Obviously you are accepting of this situation, I am not.

You missed the point. He was saying that improving the front suspension abilities = understeer, while improving the rear suspension abilities = oversteer, and I pointed out a pretty plain situation where that's blatantly wrong.

And I'm saying your "plain situation" is inheriantly flawed.

He is both correct and incorrect, as are you.

You don't simply quantify it in either instance. The main point I made is that you have to think dynamically. Sometimes you must do something that is unorthadox in order to fix an otherwise seemingly simplistic problem.

What you two are understanding is the general guidelines, but there really is no rule book to suspension tuning.

Static rigidity doesn't really mean much when we're talking about driving a car. When they are under load acting as a torsional spring they also increase rigidity.

No, the sway bar does absolutely nothing to increase rigidity of the car. Period.

It is attached to one of the most rigid components of the entire vehicle, and provides a resisting force. Not too mention those 100k mile rubber endlinks absorb an exponential amount of force and still move by hand at rest.

If your cross member is flexing as a result of the car, you have some major issues.

[InsanityInc]

It does nothing to maintain symmetry in suspension.

Just by sitting in the car you are altering the symmetry of the suspension, unless you have properly counterweighted your vehicle and aligned it.

The only thing the bar does it prevent strut tower movement, and it's resulting camber change (and toe due to cambers affect).

Do you know what the word dynamic means as it pertains to suspensions? As your chassis flexes, it alters you suspension geometry. Toe, caster and camber are all affected, and unequally so with respect to your two separate sides of the car. Reducing that flex and/or tying the suspension together makes it so the independent alteration of those suspension variables is limited.

Quote »A properly setup car, is one that does what you want it to do naturally.

The driver should ideally never have to change their driving style to accomodate for such a simple error in setup.

Obviously you are accepting of this situation, I am not. [/quote]Simple error in setup? Simply because you setup your car to have oversteer doesn't mean it will oversteer into every turn. Come into a narrow 90 degree turn at 10mph and low throttle. I don't care how your suspension is setup, you will understeer. Considering that's exactly the type of understeer you were talking about (no grip loss involved), I have no ****ing clue what you're even arguing here.

Quote »And I'm saying your "plain situation" is inheriantly flawed.

He is both correct and incorrect, as are you.

You don't simply quantify it in either instance. The main point I made is that you have to think dynamically. Sometimes you must do something that is unorthadox in order to fix an otherwise seemingly simplistic problem.[/quote]What I'm going to do here is quote what I just said, because it would seem you completely missed it.

Quote »You missed the point. He was saying that improving the front suspension abilities = understeer, while improving the rear suspension abilities = oversteer, and I pointed out a pretty plain situation where that's blatantly wrong.[/quote]See, by increasing your rear tire size relative to your front and changing nothing else, you are obviously improving the abilities of your rear end. This, however, will cause understeer, not oversteer.

Quote »No, the sway bar does absolutely nothing to increase rigidity of the car. Period.

It is attached to one of the most rigid components of the entire vehicle, and provides a resisting force. Not too mention those 100k mile rubber endlinks absorb an exponential amount of force and still move by hand at rest.

If your cross member is flexing as a result of the car, you have some major issues.[/quote]Just because it's attached to something extremely rigid doesn't mean it doesn't improve the rigidity. And yes, your cross member does flex, albeit very little. Put that much stress on any metal and it will flex. I'm not sure how you're thinking that a powerful torsional spring isn't going to increase the rigidity of the car when opposite ends of the car is what's loading that spring.

[Veriest1]

Physics.

You don't magically sustain insanely high RPM in a KA24E just because it is in the GT3 class.

Even revving the engine out to 9000 RPM would hamper it's reliability due to the horrendous piston velocity.

Most SR's are ran only to 8500 - 9000 RPM in race cars.

Engines at that racing level are measured in hours.

Obviously the class means nothing. I was just looking for some exact specifications out of curiosity and it sounded like you had some. Sorry for bothering you with it.