How does 7hp=220lbs??

[Z3_GoCar]

One other point....IF there was a misclass, was it really 5 hp? I see some opinions here that the ECU issue is responsible, if so, it's a moot point...but I also see opinions that a late year compression bump is responsible. I'd think that in reality, IF those numbers are accurate, it's a combination, so we're really talking about a possible 2 - 2.5 hp misclass. Which is a weight misclass, off the top of my head, in the 25 -35 pound range, give or take a pound or two.

[/b]

The facts:

the '94 miata 1839cc motor originally came out with 128hp and was classed at 2380lbs

the '95-'97 miata 1839cc motor was improved and uprated to 133hp, an increase of 5hp, and was added as is no additional weight.

the '96-'98 Z3 1895cc motor was rated at 140hp was originally classed at 2675lbs and has been brought down to 2600lbs

I think that Jakes states pretty clearly here that 2.5hp -> in a 25-35lbs of weight so by this we get 7hp -> in 75-120lbs of weight. So how does 133hp -> 140hp equate to 220lbs?? If on the other hand 7hp does infact justify 220lbs, then 1hp -> 31lbs and the 1.8l Miata should gain 150lbs at a minimum. If on the other hand the Miata is correctly classed the the Z3 should drop at least 150lbs. Seems pretty simple to me.


James

[JeffYoung]

Now we are really starting to sound like the production board.

[Z3_GoCar]

Hey Jeff,

I thought this line deserved a new topic rather than carry on the back of the last Fastrak. If anything Rob's shown that the car doesn't make the expected gain. Not only that, the fact that let's just slip the Miata in at the same weight.... Doesn't that run counter to how every other cars has been classed?

If it sounds like Prod, then there must be funny business going on.

James

[Andy Bettencourt]

James,

Take look at everything in ITA with 140hp. 240SX - Integra - all at or around 2600lbs. SE-R and NX are less but 'benefit' from an 'adder' for being both FWD and having front struts. The difference in weight (if you are following this thread at all) is actually 12hp as the 94-95 was classed usiing it's stock number because that was the years that were requested for classification. 12hp stock is assumed to be 15hp in IT trim and in ITA that is approximately 217.5lbs.

[Z3_GoCar]

James,

Take look at everything in ITA with 140hp. 240SX - Integra - all at or around 2600lbs. SE-R and NX are less but 'benefit' from an 'adder' for being both FWD and having front struts. The difference in weight (if you are following this thread at all) is actually 12hp as the 94-95 was classed usiing it's stock number because that was the years that were requested for classification. 12hp stock is assumed to be 15hp in IT trim and in ITA that is approximately 217.5lbs.
[/b]

The 240SX is a red herring, because it's making 140hp from a 2389cc's and has a fully independant double a-arm rear suspension, just like the miata.

The Integra makes it's 140hp from only 1835cc, four less than the 1839cc's of the miata. The fact remains that there's no reason why the miata was classed at 128hp, when it makes 133hp and is of a displacement that it should be making 140hp. The reality is that the miata and the Z3 should be really close in weight, if that's about 2600lbs then so be it, but you can't defend the miata at 2380, that's just ludicrous.

James

[JeffYoung]

James, there are probably hundreds of examples of such "inequities" in the ITCS. Part of buying in to the ITAC's process is understanding that it is not perfect. We can't have absolute parity nor is that the intent. When we think that we can, and try to achieve, we end up arguing using analogies like your above.

We are getting all bunched up over a 5 hp difference between the 94-5 and later Miatas that in my view just doesn't matter. Like I said, there are probably hundreds of these and there is just no way to correct them all.

If you think your car is classed at the wrong weight, don't argue that it should be changed by making comparisons to another car. Ask Jake and/or Andy or anyone on the ITAC to show you how they arrived at the weight in question using the process.

What the Miata weighs vis a vis your car really has nothing to do with what your car should weigh. Use the process.

[Andy Bettencourt]

While I appreciate Jeff's comments (he has working knowledge of the process as he was on the sub-committee that created ITR, and the weights), I don't think that 5hp is insignificant. It means 90lbs in ITA. It means 80lbs in ITS. It means something like 117lbs in ITC. It IS significant to some. Me included.

What I just want people to be comfortable with is that we did what we thought was right. I am confident that we would do it again in a heartbeat should the sutuation arise again - any make and model in the universe. We believe 100% that ALL the 94-97 Miata's are exactly the same in IT trim. If the classification requests came down at the same time, I believe 100% that the higher number would have been used - not because I think it is any more or less accurate, but just because of the timing. As it was, since one was already classed, it was decided that since the piece of equipment responsible for the hp bump was free in IT, that it was ok to combine them at the already published weight.

(edit: The 240SX is NOT like the Miata suspension. It has a very different upper link-based design that does not react well to lowering without special bushings, Joe knows the details and can fill us in if he chooses)

[Z3_GoCar]

Alright then let's look at the numbers for a percentage point of view:

you started out with 105 at the wheel -> 128hp at the crank
now you see 140 at the wheel -> 171hp at the crank a gain of 43hp or 33.6%

Rob started out with 140 at the crank -> 115 at the wheel
now he's got 135 at the wheel -> 165 at the crank a gain of 25hp or 17.6%

From these numbers who belongs at 2600lbs and who belongs at 2500lbs?? One's an over achiever...

and this is from a pure hp perspective not taking into account the mac-struts and trailing arms vs four wheel double a-arm

James

[JeffYoung]

1996 Z3:

Standard equipment included cast alloy wheels, leatherette upholstery and a manual top. Featured a 1.9-liter DOHC 16-valve inline 4-cylinder with 138hp @ 6,000 rpm and 133 lb-ft of torque @ 4,300 rpm and a 5-speed manual transmission.

1996 Mazda Miata M Edition:

1996 Mazda MX-5 Miata M Edition
Engine Type dual overhead cam, 16-valve inline 4-cylinder
Engine Size 1.8 liters / 110 cu. in.
Horsepower 133 @ 6500
Torque (lb-ft) 114 @ 5500

What's 19 ft lbs of torque and an apparently much flatter torque curve (peak is at 4300 rpm) worth?

James, not trying to be rude, but we could play these comparo games all day -- that's what they do on the prod board.

Ask Andy to run the 1.9 Z3 through the process and see what numbers it generates. That is what you should be asking about.

[Z3_GoCar]

Ben, I can give you the skinny on my Z3 (M44) which is the same as the 318is powerplant wise.

135hp (dynopak)136 tq. Kessler built motor, 3 different header configurations- 2 custom. Chipped ECU. Blah, blah, blah....you know the "IT" package.

The 318/z3 are no threat at 2600.

Build it!! I'd eat yellow snow for 165 tq
[/b]

Jeff, I was once told by Darrin that the Z3 was perfectly classed when it was at 2675. Well I guess he was wrong, and the current weight is still wrong. Now we've got data that says the gains are much less than the average. We've also got a car that's got gains way over the average and is under weight. When is it time to call a spade a spade?

James

[Andy Bettencourt]

Jeff, I was once told by Darrin that the Z3 was perfectly classed when it was at 2675. Well I guess he was wrong, and the current weight is still wrong. Now we've got data that says the gains are much less than the average. We've also got a car that's got gains way over the average and is under weight. When is it time to call a spade a spade?

James
[/b]

The Z3 in question has no programmable fuel system. It is not representative yet of a 'I have maxed out my power'. The Process is just an estimate. This IS IT and not Prod so the micro-managing of weights just isn't in the cards. Take the NX2000. It makes 156ish on a DynaPak. Extrapolate that to DynoJet numbers and it falls well outside it's original estimate. MUCH more so than other cars. It's not an exact science. We take the good with the bad. It has always been stated as such. One of the reasons Greg chose that car IIRC was because he thought it had 'above average' power potential. I have no issues with that as it also has 'below average handling potential' which he mitigates through development and excellent driving.

In this imperfect process, the cream will still rise to the top, we just hope it's not one car in each category like it has been in the past.

[Z3_GoCar]

....Secondly, if an engine is an airpump and it comes from the factory ALMOST fully optimized than it's naive at best to think that the gains other less optimized engines have seen will apply universally. Kessler's computer projection based on CC's, combustion chamber size and all the other inputs he used to do his calculations put the motor at EXACTLY where it dynos. Coincidence....???

.....
R
[/b]

If Kessler's done the math, and the fuel mixture is adjusted with the IT approved fuel regulator, then how can he find more power with an optimized mangement?? The truth is he's got as much as he can out of the head, valves, intake as he can. If standalone's were the end all and be all then I could dial my TEC-II for 210-220hp at the wheels, but no, I'm getting what I can get and the TEC has nothing to do with what I'm getting or Rob's getting.

James

[JeffYoung]

In regards to Andy's post above, when I say "we" I mean the royal we as in all in the IT community. I am not on the ITAC and I don't speak for it. Just wanted to be clear about that.

James, I appreciate your posts and your thoughts, but in arguing for a weight reduction on the Z3, reference to the Miata is irrelevant. Show Andy/Jake/the ITAC that the process weight for the car is wrong and you might get somewhere.

Again, what's a nearly 20 ft lbs of torque advantage worth weight wise? You dodged that one.

[Andy Bettencourt]

If Kessler's done the math, and the fuel mixture is adjusted with the IT approved fuel regulator, then how can he find more power with an optimized mangement?? [/b]

Talk with Bimmerworld on that one. Do we really have to get into this?

[Z3_GoCar]

....
1.8 Miata 2380/140 = 17.0 2380/130ft/lbs = 18.31

[/b]

Hey Jeff,

Not to dodge it but it looks to me more like a 6ft/lb advantage vs a 4hp disavantage.

James

[JeffYoung]

I'm talking stock numbers at the CRANK. See post above. That's what is used for the process with (per Jake's post) 4 levels of expected gain for the motor. The numbers you quote from Andy are (I think, post IT prep AT THE WHEEL).

Stock numbers were 133 ft. lbs for the Z3, 114 for the Miata. That's a fairly large difference adn the best "apples to apples" comparison we have before we start arguing about whether particular numbers come from a dynojet or a pack, or arguing about levels of prep for the motor, etc. Stock, the Z3 has a definite torque advantage over the Miata.

But I'm just pointing this out to highlight the fact that you can nit pick any classification you want. I can make plenty of arguments that the Z3 is heavy and others can argue it is light (decent aero with top, great brakes, good torque, the trailer arm suspension is not the disadvantage that people claim -- hell, it came off the E30 M3).

Given the numbers I've seen for the Z3, the 240SX, the Integra and the NX2000, it looks to me that the Z3 is within the 100 lb ballpark where (to me anyway) it really comes down to driver and car prep that makes the difference.

[Knestis]

I defended its honor in the other thread and I'll do it here - if the process puts the Z3 where it's currently spec'd, and the process has been followed, then that's where it should be.

K

[Z3_GoCar]

Kirk,

Darrin told me that the process put the Z3 at 2675, then it got changed to 2600, it doesn't sound like the process is as concrete as it's advertized. Then you have the fact that the cars are processed at a x% hp gain and a y% torque gain. What happens when you have a car like Andy's that gains 1.5x the hp gain and 2x the torque, compaired to a car like the Z3 where we see 3/4 of the predicted hp gain and 3ft/lbs of torque, that's like less than a 2.5% increase. Maybe I need a new tact, class the Z3 in ITB at it's current weight.

James

[Z3_GoCar]

....Stock numbers were 133 ft. lbs for the Z3, 114 for the Miata. That's a fairly large difference adn the best "apples to apples" comparison we have before we start arguing about whether particular numbers come from a dynojet or a pack, or arguing about levels of prep for the motor, etc. Stock, the Z3 has a definite torque advantage over the Miata.

But I'm just pointing this out to highlight the fact that you can nit pick any classification you want. I can make plenty of arguments that the Z3 is heavy and others can argue it is light (decent aero with top, great brakes, good torque, the trailer arm suspension is not the disadvantage that people claim -- hell, it came off the E30 M3)....

Given the numbers I've seen for the Z3, the 240SX, the Integra and the NX2000, it looks to me that the Z3 is within the 100 lb ballpark where (to me anyway) it really comes down to driver and car prep that makes the difference.
[/b]

And what do we do for a car that doesn't make those precient predictions?? After Rob sunk the money for a pro build and he's only getting 3ft-lbs more torque, that winds up being a 2.2554% gain. How about on track performance to say when a car doesn't fit the curve. How about a lap at NHIS? that's right Andy Lapped Rob there, pretty good for a handeling car at a power car track. On to the other extreme LRP Rob was down 3 seccond on his best lap from Andy and finished 8.5 seconds back.

As for the trailing arms, they're a known defficiency, especially when compaired to the double a-arms that miata's and the 240sx have. Also, what happens when you bend a sub-frame and get toe out, round you go all the time. To fix it you've got to resort to welding on "reinforcing" adjustors that are definetly in the grey.

James

[JeffYoung]

You are saying that an IT build on a Z3 1.9 only gets you 3 ft lbs at the wheels?? If so, I'd be talking to my builder.

James, at this point, just have to say you and I come at classing cars for IT from two different planets. I'm comfortable that the process is presently as fair as it can get. You can argue an inequity for ANY car on the ITCS if you only focus on this factor, or that number. I won't even open the on track performance can of worms.

Just have to leave it at that.