What determines the mid engine adder?

[CRallo]

Where's the little icon for slipery slopes?

+1!

[Andy Bettencourt]

It's not slippery unless you make it slippery. It's not a 'balance' adder. It's a braking adder. Mid and rear engined cars are better on brakes given weight transfer. It is added in a very easy and cosnsitant way. Agree or disagree, it is not slippery.

[Greg Amy]

It's not a 'balance' adder. It's a braking adder. Mid and rear engined cars are better on brakes given weight transfer.

Whaaa...? You say it has nothing to do with balance, that it's due to braking...'cause the drivetrain's in the back...which improves braking because...there's better F/R balance.

Dee-duh-dee.

It is added in a very easy and cosnsitant way.

No, it's not. It's only added to a very small group of "mid-rear engined" cars, and apparently not in ITR. And all other cars with good F/R balance - which in most cases will improve their braking (the stated reason for the adder), despite not being "mid-rear engined" - are ignored.



GA

[Andy Bettencourt]

Seperate braking balance and handling balance in your mind. I didn't invent it, just telling you what it is.

Mid-rear engined car will brake better and more cosistantly than the other front-engined layouts, everthing being equal. And remember, adders are applied REALATIVE to their classed counterparts so you have to look at them that way as well. The first gen MR2 is now in ITB with some pretty old tech.

If there is a contingent that feels the mid-engined, better under brakes adder of 50lbs for ITC-ITS is bogus, feel free to write in. It is applied so infrequently that it doesn't get much of a scrub-down.

[quadzjr]

so we went from blance to braking.. OK..

Braking in a straight line.. yes.. it will be more stable than a FWD or a F-R car.. but then a rear engined car would be even more stable braking in a straight line.

Do I get a break for the inability to trail brake since the rear end snap overstears and there is little chance to catch it? Or how about on long sweeping corners that the car, even in stock form, goes back and forth from understeer to oversteer back understeer in mid corner multiple times?

From the sounds of it, it is a competition adjustment that is not based on physics or empircal data, in a class (IT) that doesn't make competition adjustments.

Like I said before, I was just thinking.. It really doesn't matter.. I was just wondering..

[Chip42]

if it has to do with braking stability, why don't we just pause and note that neither the mkI MR2 nor the 914-4 have stellar braking systems.

granted, they beat many of the older (than the 2) cars in their classes, and I am certainly NOT complaining in the face of a weight break, but this wieght adder seems entirely subjective. does the 944 in ITS have this adder? (it certianly has a large amount of weight in the rear due to the transaxle) from what I gather - it wouldn't.

I understand the assertion that the mid-rear adder is consistantly applied, but I see it as being applied consistently to an inconsistant portion of the group to which it would seem to apply.

a slippert slop indeed. still, the current process is far superior to the old way of doing things. I agree that it would be very nice to see what cars recieve what handicap over and above the 25% gains and class PWR.

[quadzjr]

If there is a contingent that feels the mid-engined, better under brakes adder of 50lbs for ITC-ITS is bogus, feel free to write in. It is applied so infrequently that it doesn't get much of a scrub-down.

Just because it happens infrequntly (relatively few cars with a MR layout are legal for IT) doesn't mean it is right and can be jsut left by the way side.

[Greg Amy]

Mid-rear engined car will brake better and more cosistantly than the other front-engined layouts, everthing being equal.

OK, Andy, your turn: separate in your mind where the engine is located.

You state these cars brake better and more consistently; why? Is it solely because the engine is behind the driver, or is it because they have better F/R weight balance (trust me: this isn't a trick question)? Do these cars brake better because there's an engine in back, or do they brake better because of an advantageous weight distribution?

Do these cars brake better because there's a better F/R weight distribution, or is there a better F/R weight balance because they brake better? What is the root reason here? You're tunnel-visioning on the mechanics of the result, rather than the result.

If a car had the engine behind the driver, but still had a 60F/30R weight balance, would it still get the adder? And - key point at hand here - if the car had better F/R weight distribution, but the engine was in front of the driver, would it get the adder?

Root cause -- > result.

If there is a contingent that feels the mid-engined, better under brakes adder of 50lbs for ITC-ITS is bogus, feel free to write in.

Note that I am not arguing whether or not it should be applied as an adder; I'm simply arguing that it should be applied consistently and fairly using the features it's now purported to apply (despite its mis-naming): better braking, which is due to advantageous F/R weight distribution. - GA

[Andy Bettencourt]

so we went from blance to braking.. OK..

Braking in a straight line.. yes.. it will be more stable than a FWD or a F-R car.. but then a rear engined car would be even more stable braking in a straight line.

Do I get a break for the inability to trail brake since the rear end snap overstears and there is little chance to catch it? Or how about on long sweeping corners that the car, even in stock form, goes back and forth from understeer to oversteer back understeer in mid corner multiple times?

From the sounds of it, it is a competition adjustment that is not based on physics or empircal data, in a class (IT) that doesn't make competition adjustments.

Like I said before, I was just thinking.. It really doesn't matter.. I was just wondering..

Just for the record, YOU guys went from balance to braking. In my mind, this adder has always been about braking. Now like I said, love it or hate it, it is what it is and is not a slippery slope. It is applied, right or wrong, to the same cars in the same classes (S-C). If you feel it is wrong, write in and tell us why.

[Greg Amy]

Just for the record, YOU guys went from balance to braking. In my mind, this adder has always been about braking.

It's not a 'balance' adder. It's a braking adder.

Something that's always been presented as a "mid-engine adder", and all of a sudden WE are changing our tunes? Maybe it's the ITAC that needs to present its case better...?

[Andy Bettencourt]

OK, Andy, your turn: separate in your mind where the engine is located.

You state these cars brake better and more consistently; why? Is it solely because the engine is behind the driver, or is it because they have better F/R weight balance (trust me: this isn't a trick question)? Do these cars brake better because there's an engine in back, or do they brake better because of an advantageous weight distribution?

Do these cars brake better because there's a better F/R weight distribution, or is there a better F/R weight balance because they brake better? What is the root reason here? You're tunnel-visioning on the mechanics of the result, rather than the result.

If a car had the engine behind the driver, but still had a 60F/30R weight balance, would it still get the adder? And - key point at hand here - if the car had better F/R weight distribution, but the engine was in front of the driver, would it get the adder?

Root cause -- > result.

Note that I am not arguing whether or not it should be applied as an adder; I'm simply arguing that it should be applied consistently and fairly using the features it's now purported to apply (despite its mis-naming): better braking, which is due to advantageous F/R weight distribution. - GA

It's frustrating Greg that you argue and nit-pick and then don't take a position. All I am doing is telling you how tha adder is applied in it's most simple form because that is what has been asked - yet you inply that we don't have the brains to understand the fundamantals. Doing it or not, it's how it comes off.

I feel they brake better because that have a weight distribution that facilitates better braking. Typically a rearward bias...not a 50-50. It's about weight distribution under decelleration. I would love to see the car that had a 60-30 (60-40 or 70-30?) balance that had a mid-rear layout...and I would NOT vote for the adder. I would go on record as explaining that even though the mechanical characteristic is there, the physical characteristic we are applying for is not. We can never take 100% of subjectivity out of the process, especially when the improbable is proposed.

So in the end, there are always checks and balances and rechecks. It's why the con-calls go for 5+ hours and a straight formula isn't used.

[Andy Bettencourt]

Something that's always been presented as a "mid-engine adder", and all of a sudden WE are changing our tunes? Maybe it's the ITAC that needs to present its case better...?

Again, the question was 'why is mid-rear deservant of an adder'? Braking ability is the answer, not 'handling balance' like is being assumed.

[ekim952522000]

Guys instead of beating up on Andy if we don't like this, how about we put together a proposal to get it changed?

But I have to ask is it the adder we don't like or the fact that it is only applied to mid-rear cars?

Do we agree with a weight Balance adder if it is applied to for example all cars that are 45/55 or more rear biased?

[quadzjr]

I am not beating up on Andy.. he is just the only person that has responded to my question. In all sinserity.. I appreciate his response. I had a question.. he answered it.

I believe IIRC the MK1 weight % is 44.5/55.5 +/- a perecent or so.

I think we are finally coming to some sort of a conclusion.. To re-iterate the adder is subjective based on weight distrubtion that is provided by the MR layout to provide better braking stability.

However that weight distrubtion is a hindernace on other parts on the track. If by chance that it is found that the cars really dont' have an advantage, does the adder go away? I guess that would be hard to prove, many times it has been stated on this site before that on track results are a weak excuse at best.

[ekim952522000]

Let's start by listing all of the mid-rear cars in IT factory weight balance. Let me know if I missed any. I don't know much about Porsche I may have missed a few of them.

Toyota MR-2 (90-94) ITA

Toyota MR-2 1.6L (85-89) ITB

Porsche Boxster (97-99) ITR

Porsche 914-4 1.8 (74-75) ITB

Porsche 914-4 2.0L (73-76) ITB

Porsche 914-4 1.7 (70-73) ITC

If you can find these online please post a link to the results I will look aswell.

Then after we find the weight balance for all of these we need to see if there are other cars in the same class as these that have the same, or more of a rearward weight bias.

We need to check against the rear engine cars as well.

I think that will be a good first step. Then we will have to discuss if we think it should get applied to all of these cars equally, or none of them.

[ekim952522000]

.....

I believe IIRC the MK1 weight % is 44.5/55.5 +/- a perecent or so.

....

ok are there any front or rear engined cars in ITB that have as much or more rear bias. I am asking because if it is a weight balance adder the first thing to figure out is if it is being applied equally regardless of engine location.

[quadzjr]

Fiat X1/9 roles in at 41/59 I believe.

But I am a for of getting rid of it entirely.. do to the fact that where it's weight distubtion may help in one area, it is a hinderance in another.

However it is hard to remain un-biased when I am building one currently.. But it is because of that fact that I even thought about this in the first place. another point as a continuation of the FWD adder conversation, is that if and when it is applied why is it a flat 50lbs.. when weight plays such a higher roll in slower class cars.

[ekim952522000]

I also understand the adder but do not agree with it either.

It "seems" like no one agrees with it. Is there anyone on the forum who thinks we should include weight bias in the process?

My biggest problem with it is that we remove so much stuff from the cars and then add a cage I am not sure the stock weight balance number is really a reflection of what the cars end up.

[Knestis]

Guys instead of beating up on Andy if we don't like this, how about we put together a proposal to get it changed?

But I have to ask is it the adder we don't like or the fact that it is only applied to mid-rear cars?

Do we agree with a weight Balance adder if it is applied to for example all cars that are 45/55 or more rear biased?

Since this isn't a "rule" as such, there's no formal mechanism for proposing a "change," I don't think. You could lodge your questions/concerns through letters to the Board but additional back-channel discussion can be helpful.

I'd love to hear (much like with the torque and FWD questions) options for understanding what's going on at a theoretical level. There's a tendency for folks to jump to the end of the story, staking out a position that's consistent with their interests rather than exploring the whys involved.

EDIT - For example, a case might be made that a rear-drive, rear-mid-engined platform benefits from longitudinal weight transfer in both braking AND acceleration. It also might be that the low PMOI issue described above (the snap spin behavior) is either a curse or a blessing, depending on how fast one's hands are.

And (as is typical) there's potential for a LOT of mixing of issues/influences/rationales/etc. It's very helpful - to me, anyway - if we can be as clear as possible about WHAT we're talking about. Start by explicitly defining your terms.

K

[Knestis]

... My biggest problem with it is that we remove so much stuff from the cars and then add a cage I am not sure the stock weight balance number is really a reflection of what the cars end up.

A good question. We need to remember that we start at "stock" in all instances but go from there.

On anecdote, I'd initially *think* that if anything, balance would tend to go more in whichever direction it starts. When we cleaned out the Golf shell, it ended up being a big box of air in the back. We couldn't take much at all out from the dash forward.

K