Porsche 944S

[latebrake]

Originally posted by Andy Bettencourt@Dec 20 2005, 11:47 AM
T-bar rear - yes...wasn't thinking along those lines when replying to the comment.

The highest stock HP ITS 240SX makes 155. 2 less than the 944. *IF* the 944 was reduced to 2550, it would be 100lbs less than the 240SX.

So lets compare:

240SX
155hp * 25% IT-prep increase = 194hp.

944
157hp * Jon M. know best chp = 185hp.

I think these cars are just fine in the same class. The 944 may not be a world-beater in ITS but it is no slam-dunk in ITA.

AB

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Hi Andy,

I dont know what the 240 weight is in IT. What is it? The problem with the 944 in IT just may be that the top drives arent driving many of them. All the upgrades wont fix that. If the playing field is truly level,or as flat as it can be made with machines then the bark about the 944 not being a contender in ITS is just the way of it and thats that.

On the other hand there are a ton of these cars around for donors and if its Ok for 9 to 10 hp on one side why cant it be OK on the other side? If the 240/944 are 9 Hp apart now and the 100# less for the 944 where does the math come out there? I used to know the hp/weight was but forgot. I was trying to increase the hp of my car by getting rid of some of my fat butt and somehow the 14.5# gave me one more HP seems to come to mind here. help me out some if you know. HA!!

Will the 2550# 944 have more than 9 Hp over 240 at current weight?
The 944 is going to drop 18 to 20% hp through the drive line. This can be made a little better with AT fluid in the trans and keeping the T-tube real lubed but not much. I did the AT fluid thing but put the red line back in,just didnt feel like a good idea to me.

Lawrence

[Andy Bettencourt]

Originally posted by latebrake@Dec 20 2005, 11:08 AM
Hi Andy,

I dont know what the 240 weight is in IT. What is it? The problem with the 944 in IT just may be that the top drives arent driving many of them. All the upgrades wont fix that. If the playing field is truly level,or as flat as it can be made with machines then the bark about the 944 not being a contender in ITS is just the way of it and thats that.

On the other hand there are a ton of these cars around for donors and if its Ok for 9 to 10 hp on one side why cant it be OK on the other side? If the 240/944 are 9 Hp apart now and the 100# less for the 944 where does the math come out there? I used to know the hp/weight was but forgot. I was trying to increase the hp of my car by getting rid of some of my fat butt and somehow the 14.5# gave me one more HP seems to come to mind here. help me out some if you know. HA!!

Will the 2550# 944 have more than 9 Hp over 240 at current weight?
The 944 is going to drop 18 to 20% hp through the drive line. This can be made a little better with AT fluid in the trans and keeping the T-tube real lubed but not much. I did the AT fluid thing but put the red line back in,just didnt feel like a good idea to me.

Lawrence

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The 240's in ITS have a min weight of 2650. We have to use a repeatable process when we do this so who is driving them really doesn't matter. It's a data point, but not something that would carry any more weight than anything else.

I am not sure what you are getting at on the hp. 9hp on one side and 100lbs difference vs. 9lbs on the otherside with...what? 100lbs more for a 200lb difference? Not sure what you are asking for here.

All the numbers for the math are there for you (plus some more for you):

240SX: 194hp estimate / 2650 = 13.45
944: 185hp documented / 2550 = 13.78
944S: 210hp documented / 2850 = 13.57
Integra GSR: 200hp estimate / 2680 = 13.45

Would you like to factor in the fact the Porsches have 10% larger brakes than the Nissan (283mm vs. 257mm) and 8% larger than the Integra?

From my experience, most RWD cars drop about 18% through the driveline.

Like I said, it may not be the BEST car for the class, but it ain't crap either. The PROPOSED correction should make things much better.

[Fastfred92]

Originally posted by Andy Bettencourt@Dec 20 2005, 06:05 PM
The 240's in ITS have a min weight of 2650. We have to use a repeatable process when we do this so who is driving them really doesn't matter. It's a data point, but not something that would carry any more weight than anything else.

I am not sure what you are getting at on the hp. 9hp on one side and 100lbs difference vs. 9lbs on the otherside with...what? 100lbs more for a 200lb difference? Not sure what you are asking for here.

All the numbers for the math are there for you (plus some more for you):

240SX: 194hp estimate / 2650 = 13.45
944: 185hp documented / 2550 = 13.78
944S: 210hp documented / 2850 = 13.57
Integra GSR: 200hp estimate / 2680 = 13.45

Would you like to factor in the fact the Porsches have 10% larger brakes than the Nissan (283mm vs. 257mm) and 8% larger than the Integra?

From my experience, most RWD cars drop about 18% through the driveline.

Like I said, it may not be the BEST car for the class, but it ain't crap either. The PROPOSED correction should make things much better.

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Andy
What is the target hp/weight for A??

[latebrake]

Originally posted by Andy Bettencourt@Dec 20 2005, 02:05 PM
The 240's in ITS have a min weight of 2650. We have to use a repeatable process when we do this so who is driving them really doesn't matter. It's a data point, but not something that would carry any more weight than anything else.

I am not sure what you are getting at on the hp. 9hp on one side and 100lbs difference vs. 9lbs on the otherside with...what? 100lbs more for a 200lb difference? Not sure what you are asking for here.

All the numbers for the math are there for you (plus some more for you):

240SX: 194hp estimate / 2650 = 13.45
944: 185hp documented / 2550 = 13.78
944S: 210hp documented / 2850 = 13.57
Integra GSR: 200hp estimate / 2680 = 13.45

Would you like to factor in the fact the Porsches have 10% larger brakes than the Nissan (283mm vs. 257mm) and 8% larger than the Integra?

From my experience, most RWD cars drop about 18% through the driveline.

Like I said, it may not be the BEST car for the class, but it ain't crap either. The PROPOSED correction should make things much better.

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Maybe I am off base here. I thought the 2550# for the 944 was not going to happen. 13.45 for the 240 and 13.78 for the 944 is splitting frog hairs and should but the cars on a level playing field hp/# wise.

I thought the last post had the 240 at 9 more hp than the 944 at a higher weight. and was just stating that the difference in proposed weight for the 944 could give it 9 more hp, weight to hp wise over the 240 should just as OK. You know,kind of like if we are going to give an advantage to someone lets make it ME!!
Just having fun Andy.
I dont know you or drive in IT for that matter so I have a small dog in this fight but I just may build another car someday and I like the 944 platform.

Dont pay any mind to that brake thing,can we just forget about that part? Cant hurt to ask.

Lawrence

[924Guy]

Sorry, Andy - but I GOTTA take issue with your gross assumption on the brake thing there. You need a more precise comparison of brake swept area, not rotor diameter. The reason why is that the hubs on our cars are HUGE. The bolt circle is 5x130mm. As a result, while outer rotor diameter is larger than usual, there is additional area lost inside, so it's not the huge advantage you think. As for rotor effective diameter - big deal, change pads, same difference.

Just trying to keep the accounting straight. FWIW, I feel the following about the 944's:
- 2550 is doable in IT-legal trim - but will be a challenge if the driver's not up to his/her end of the bargain! My 924 weighs about 2400 without me or ballast, and still maybe 1/4 tank of gas; weighs 2600 and change after a race.

- I still doubt the 8V cars will be able to really compete against the big guns in ITS; I think it's more likely to succeed in ITA with more weight thrown on it. But then, caution may be the higher priority at the moment, and a weight reduction is still progress vs. nothing.

- All those guys running 944Cup, Spec 944, and GTS Challenge with their 944's aren't going to leave and jump ship to ITS next year. They've already got a happy place they really love to play, that fits them perfectly. Those seeking a higher challenge do look to ITS, but are discouraged by the current situation and I don't think they're going to be swayed by moving 150#. They're not exactly running 10/10ths ITS cars right now. If you're after them, you're going to need to let them fight it out with the ITA cars with ballast. Even if that turns out not to be the right thing for IT. Hey, all those PCA cars still have carpet, remember! This is as much culture as it is competitiveness.

[JimLill]

Regarding brakes....

- larger diameters can offer some small advantage on cooling assuming the wheel size is appropriate

- correct, swept area is what counts, so you need to look at pad dimensions to get the minor and major diameters and calculate from there.

- larger diameters do offer more leverage, so more brake torque is generated for the same pad force albeit at the expense of "pad speed"

Bottom Line: comparison can be tricky!

[924Guy]

Agreed on all counts, but that's why I was bringing up my points - either get it right or don't even bring it up! Sorry, being an engineer on the brake side of things, I get real picky about this kind of stuff.

The other issue I have here about rotor diameter relating to brake output - it's irrelevant to an IT discussion if you're simply trying to talk about specific brake output. That's because friction material selection is even more fundamental to brake output, yet it's unregulated in IT. Not that it should be - just pointing out that one uncontrolled variable invalidates the rest of the argument, IMO. So I feel that there can be excessive focus put on the idea of brake output in classifying IT cars, relative to the amount of regulation applied.

[Andy Bettencourt]

Originally posted by 924Guy@Dec 23 2005, 10:48 AM
Agreed on all counts, but that's why I was bringing up my points - either get it right or don't even bring it up! Sorry, being an engineer on the brake side of things, I get real picky about this kind of stuff.

The other issue I have here about rotor diameter relating to brake output - it's irrelevant to an IT discussion if you're simply trying to talk about specific brake output. That's because friction material selection is even more fundamental to brake output, yet it's unregulated in IT. Not that it should be - just pointing out that one uncontrolled variable invalidates the rest of the argument, IMO. So I feel that there can be excessive focus put on the idea of brake output in classifying IT cars, relative to the amount of regulation applied.

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So what do your swept are comparisons show on a 944/924/944S vs. the competition?

While your point is valid, I still see no data that shows the Porsche doesn't have an advantage (or disadvantage).

AB

[924Guy]

So what do your swept are comparisons show on a 944/924/944S vs. the competition?

While your point is valid, I still see no data that shows the Porsche doesn't have an advantage (or disadvantage).

I don't have any data for other cars, sorry. (Edit - so I haven't bothered to determine it for our cars)

Advantage or disadvantage - where? In brake size? In brake output? Specifically what charactaristics of the brake package on a car is the CRB concerned with when reviewing classifications/weights/performance potential?

Finally - did I say that the Porsches does not have an advantage, or has a disadvantage? Please read my comments again, then tell me what you think I said or implied; if I am misunderstood I'd like to clear that up.

OK, I'll take my numbers nerd hat off now...

[Andy Bettencourt]

Originally posted by 924Guy@Dec 23 2005, 03:15 PM
I don't have any data for other cars, sorry. (Edit - so I haven't bothered to determine it for our cars)

Advantage or disadvantage - where? In brake size? In brake output? Specifically what charactaristics of the brake package on a car is the CRB concerned with when reviewing classifications/weights/performance potential?

Finally - did I say that the Porsches does not have an advantage, or has a disadvantage? Please read my comments again, then tell me what you think I said or implied; if I am misunderstood I'd like to clear that up.

OK, I'll take my numbers nerd hat off now...

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I thought you said that the brake size wasn't an advantage because of hub size etc. I agree that you have to measure swept area to truely understand, so I figured you had that data since you implied the 944 didn't have superior brakes as compared to the others I quoted.

AB

[Geo]

Originally posted by 924Guy@Dec 23 2005, 09:48 AM
Agreed on all counts, but that's why I was bringing up my points - either get it right or don't even bring it up! Sorry, being an engineer on the brake side of things, I get real picky about this kind of stuff.

The other issue I have here about rotor diameter relating to brake output - it's irrelevant to an IT discussion if you're simply trying to talk about specific brake output. That's because friction material selection is even more fundamental to brake output, yet it's unregulated in IT. Not that it should be - just pointing out that one uncontrolled variable invalidates the rest of the argument, IMO. So I feel that there can be excessive focus put on the idea of brake output in classifying IT cars, relative to the amount of regulation applied.

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Being a 944 guy I'd love to say we got shafted a bit on the brakes. I don't think it's true. Overall I think the car should have caught a bit better break (pun intended), but I think it's in the range where arguing is rather moot. I do of course agree with your point, however gross differences can and should be taken into account. We all know the 944 does have excellent brakes (for whatever reason) and say the 240Z has crummy brakes.

Like Andy, as a member of the ITAC I would be interested in your professional opinion what we should take into account. Keep in mind that as you noted, friction material is free, so assume the same or optimal friction material for comparison.

[924Guy]

Originally posted by Andy Bettencourt@Dec 23 2005, 05:07 PM
I thought you said that the brake size wasn't an advantage because of hub size etc. I agree that you have to measure swept area to truely understand, so I figured you had that data since you implied the 944 didn't have superior brakes as compared to the others I quoted.

AB

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Sorry - those were your assumptions only. I said that the advantage was overstated because the abnormally large (Porsches are the only cars I've ever seen with a bolt circle approaching 130mm) hub size.

I do agree that the comparison should be of swept area, as the most technically meaningful (IMO) data point. In addition to the obvious, which is to say disc vs drum and solid vs. vented, which I'm more than sure has long been taken into account.

Thanks...

[924Guy]

Oh, yeah, I suspect the reason the 924/944 is felt to have better than average brakes is more a function of vehicle balance and suspension design than raw brake output. Those who've raced the 924 with the solid disc/rear drum setup have reported similar excellent properties (once a proper race material is installed and the rear drums are properly adjusted). Having recently beat the crap out of a C5 on an autox, I can say the P-cars are definitely far more stable under heavy braking! But then, the C5 is a classic example of a car that only does one thing well at a time, and I digress...

[JimLill]

re: Brakes.... let's assume Kinetic Energy, thus vehicle weight and swept area are the only factors.

The 944S has a ~8% disadvantage weight-wise but a 24-29% advantage swept area-wise based upon approx. pad sizes.

[Andy Bettencourt]

Originally posted by 924Guy@Dec 24 2005, 09:32 AM
But then, the C5 is a classic example of a car that only does one thing well at a time, and I digress...

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Except a C5 has won Super Stock at the Solo Nationals since 2000...



AB

[924Guy]

Originally posted by JimLill+Dec 24 2005, 03:49 PM-->

re: Brakes.... let's assume Kinetic Energy, thus vehicle weight and swept area are the only factors.[/b]

I'm good with that, I feel that's appropriate

<!--QuoteBegin-JimLill@Dec 24 2005, 03:49 PM
The 944S has a ~8% disadvantage weight-wise but a 24-29% advantage swept area-wise based upon approx. pad sizes.

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Can&#39;t argue against that - I don&#39;t have data. I assume you&#39;ve taken a survey of some leading ITS competitors? Which ones?

[JimLill]

Originally posted by 924Guy@Dec 25 2005, 11:49 AM
I&#39;m good with that, I feel that&#39;s appropriate
Can&#39;t argue against that - I don&#39;t have data. I assume you&#39;ve taken a survey of some leading ITS competitors? Which ones?

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The 240SX and Integra cited above in the thread.......

[RR]

You are totaly wrong about brake size. The 944 and 944S use the exact same caliper, rotor and pad. Look it up on any parts list. In fact the only difference in the two cars besides the head is the gears are about 3-5% taller, making the 944S gears/tranny much worse for racing.

[JimLill]

Originally posted by RR@Dec 27 2005, 07:14 PM
You are totaly wrong about brake size. The 944 and 944S use the exact same caliper, rotor and pad. Look it up on any parts list. In fact the only difference in the two cars besides the head is the gears are about 3-5% taller, making the 944S gears/tranny much worse for racing.

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I&#39;m not sure who you are replying to....

My analysis is for the 944S (using dims from ITS specs) to the 240SX and Integra

[RR]

I thought you were comparing the 944 to the 944S. If you want an interesting brake comparison, check the front double-piston RX7 swept/area size to the single piston 944. I think the RX7 has quite the advantage, would anyone disagree?