ITA RX7 Tubing size

[dyoungre]

Originally posted by lateapex911@Aug 30 2005, 06:37 AM
In terms of moving the car to ITB and using a stock manifold to restrict the power, that wheel number is too low to fit competitively.

A move to B would require, basically, 12 new wheels, (race, test and rain tire sets) a change in tire section, (due to lack of sizes avaible) which would likely result in an overall diameter change, necessitating the re-gearing of the axle.

Then there would be the testing and re-setup to accomodate the change in ride height and change in center of gravity.

A move to B isn't easy!

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Jake,
I understand your point; I think that ANY change will require a financial and sweat equity impact, and I don't want to minimize that fact. I think it is cheaper in the long run, though, than selling an uncompetitive car and buying/building a new car simply because it is (now) better classed.

The more I think about it, the more I like the idea of an overlap rule for recognized tweeners: race ITA at one weight with ITA wheels/rules, and ITB at a higher weight with ITB rules. No car should be classed as such as new, but I could see legacy cars being allowed the opportunity to compete in the lower class.

[Jake]

Originally posted by dyoungre@Aug 30 2005, 01:19 PM
The more I think about it, the more I like the idea of an overlap rule for recognized tweeners: race ITA at one weight with ITA wheels/rules, and ITB at a higher weight with ITB rules. No car should be classed as such as new, but I could see legacy cars being allowed the opportunity to compete in the lower class.

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That sounds like an excellent idea. Why not?! If I drove a Miata I could pick and choose what class I wanted to run in.

[ddewhurst]

***The more I think about it, the more I like the idea of an overlap rule for recognized tweeners: race ITA at one weight with ITA wheels/rules, and ITB at a higher weight with ITB rules. No car should be classed as such as new, but I could see legacy cars being allowed the opportunity to compete in the lower class.***

I also like this as a method of allowing car owners to make THEIR DECISION on which class they run. Many of us understand that we will not win given either class. Or at least we SHOULD UNDERSTAND. Given the choice of A or B I would continue to run A. I can live with doing my best at lowering my lap times in A & finishing less than 1st. If there comes a day when I have a desire to win then I can spend whatever & change to B.

[mustanghammer]

My car was originally built with 1.75x.120 tubing in the mid 90's. Now it has a mix of 1.5x095 and the original 1.75x.120 tubing. All of the ITA/EP RX7's that I have seen built in KC have 1.5 X.095 tubing.

I would also support dual classing of the RX7 between ITA and ITB. As one of the 4 MiDiv IT7 regulars I too think that the ability to compete competitively in an offical IT class offers me more of a future in IT.

[dickita15]

Well I have three cars in my shop, two of which are being activley raced. I checked today and they are all 1.75 tubing ranging from .100 to .137 (wow) thickness.

i would love to hear more real world data

[dickita15]

I spoke with another car owner last night 1.5 x .120. It looks like many of have heavy cages.

[Speed Raycer]

Originally posted by dickita15@Aug 31 2005, 06:11 AM
I spoke with another car owner last night 1.5 x .120. It looks like many of have heavy cages.

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LOL by my count in this topic, its 6 .120+ to 5 .095's... not counting every RX built by KC Raceware using .095. If they only built 1, then were running 50%

[dyoungre]

Originally posted by Speed Raycer@Aug 31 2005, 02:23 PM
LOL by my count in this topic, its 6 .120+ to 5 .095's... not counting every RX built by KC Raceware using .095. If they only built 1, then were running 50% ;)

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I was suprised by how many cages were built with .095, but I think the knowledge that it is 50/50 could support making a decision that provides an opportunity for 1/2 the existing cars.

[Speed Raycer]

If it truely was 50/50, then the dual class @ different weights might work. Those cars that are 10/10ths with the .095 cages can run in A @ 2380/2200 and those with the heavier cages have the option of B @ xxxx/>2200

Other options.... ITB cars get rear drums, 81-85 intake manifolds and ....

IMO, the biggest thing to slow the car down would be the exhaust and possibly the Intake manifolds being restricted to 81-85's. Most guys seem to be running a "stock" Nikki carb anyway.

Personally, I'm so slow in my RX that I end up racing the B guys anyway (and loosing)

[mustanghammer]

"not counting every RX built by KC Raceware using .095. If they only built 1, then were running 50%"


KC Raceware has built 3 ITA RX7's, 1 ITS 2nd gen and 3 EP first gen RX7's

Of the ITA cars:

1 ITA RX7 is owned by someone in KC - 1st IT car that KC Raceware built
1 was killed at an ARRC by Charlie Clark - it's cage is in an another car that is nearing completion
1 was converted to E Production - Chuck Clark's car

They didn't build my car all though it has a Nico fabricated exhaust and a Nico installed driver's door bar.

So there is one out there but it is inactive at present.

Regarding the ITB ideas that are floating around. I really like some of the restrictions that are being proposed instead of adding massive amounts of weight. A heavy car on narrow rims will be a tire and brake killer. Not to mention that this would be hard on already fragile front spindles. I would much rather give up a header and my rear disks than add another 100lbs to my already bloated ITA/IT7 car.

[ddewhurst]

Those of you that think giving up the rear disc are a good idea obviously race on tracks where required HARD braking is not required. My second race out in my at the time SRX7 at Blackhawk Farm was with 75% rear shoe remaining & 10 laps in the brakes went south. The rear shoes were GONE.

The car never went on track again untill the disc brake rear went in & it will never go on track again without rear discs.

BAD IDEA folks.............

[dickita15]

I agree david
if weight is not an easy way to limit performance on tweeners that I would rather limit power that hurt brakes.

a question for the ITAC guys. has there been any discussion of the SIR restritor like the are now useing in GTL instead of the more conventional flat plate. It seem like a pretty cool piece.

[Dick Elliott]

What do you think we used for the first few years of IT? Rear disc were not allowed in IT on a RX-7 for several years after the class became a SCCA class. I think 84 was the first year, and rear disc were not legal untill the 85s became legal for IT. We did just fine with rear drums, and I know people who still use them in IT. My own GT-2 RX-7 used drums in the early 80s with no problems. Just a tale from the past.



The car never went on track again untill the disc brake rear went in & it will never go on track again without rear discs.

BAD IDEA folks.............

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[/quote]

[mustanghammer]

Originally posted by ddewhurst@Aug 31 2005, 07:16 PM
Those of you that think giving up the rear disc are a good idea obviously race on tracks where required HARD braking is not required. My second race out in my at the time SRX7 at Blackhawk Farm was with 75% rear shoe remaining & 10 laps in the brakes went south. The rear shoes were GONE.

The car never went on track again untill the disc brake rear went in & it will never go on track again without rear discs.

BAD IDEA folks.............

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Okay, I agree. I seem to recall that Charlie Clark had the same experience with his fisrt 1st Gen RX7 when it was in ITS. I would and will not propose this.

Devils Advocate here:

With some exceptions there seems to be an agreement that the 1st Gen RX7 12A cannot compete in ITA. From the paper and on track data that I have seen in the Midiv and at the ARRC the 1st gen RX7 is a good fit in ITB as is. So why does an RX7 need to give anything up, other than 7" wheel width to compete in ITB? Under what formula is an RX7, a car that has no torque but decent HP, an instant over-dog in ITB?

Flame away....but seriously what is the objective reason why this is not true?

[lateapex911]

Not that lap times should be taken with too much importance, butttt.....

Last years ARRC laps, in equal track conditions:

IT7: Lukas- 1:47.3
ITB: Blethen- 1:48.6
ITA: Serra- 1:43.3

IIRC, LOL, there was about 1.35 second or so differenece on a track almost 2 minutes long. Of course the track isn't representive of every track, but, ...

Well, the ITA cars were running 1:43.3, so the RX-7 was closer by far to ITB than ITA, LOL

[lateapex911]

OK- let me suggest some big picture thinking here....Blue sky stuff.

Question 1-
IF the car can't go to ITB for whatever reason, what would you do in ITA to make it more viable. Remember, blue sky, but show your math, so to speak.

Question 2-

If the car goes to B, how will you make it fit?


Dick- The SIR is an item being discussed, but there are no immediate plans to implement it to any specific car as far as I know, at this time.

The joy, from what I understand, of the SIR, is, unlike the typical plate restrictor, is that it is "invisible" to the system until it reaches it's effect threshold, then that's it...no more air. So, throttle response is unaltered, midrange power is the same, but peak hp is capped.

The other cool thing is the simplicity of the item. The math, from what I understand is clean and consistant. You buy the little donut looking thing, and put on the end of your snorkel. All air passes thru it, and thats it, you're done.

It is very common in many classes, you can see it on the ALMS LMP2 cars in the nose, and hanging off the sides of certain Formula cars. It's been around for awhile, and has a good reputation. As the shape has already been optimized it is basically tamper proof.

From MY point of view, it seems like an item that can make a car that is a current overdog for a class, and has weight issues, fit the class in an easy to check, and cheap way.

[Eagle7]

Sorry to go a little off-topic, but is there any reason why an SIR wouldn't have been a good choice for the BMW in ITS? How would its effect on a 12A compare with its effect on a boinker?

[lateapex911]

I think an SIR is a very viable option for the E36.

I think, (it's being researched as we speak) that it could be very effective on a rotary.

[Marcus Miller]

Based on the ARRC lap times form last year, it loks like we need to pick up 4 seconds, which seems extremely difficult, or lose a second.

I'm assuming the quickest and easiest way to pick up four seconds at Road Atlanta would be horsepower.. the only way to do that is porting, similar to what is allowed for piston motors. I think we all know (believe) that is not going to be allowed, and likely would not be enough, anyway.

To lose a second per lap, maybe I'm way off base, but I think the 6 inch wide wheels would do it; beyond that, maybe restrict the cars to only using stock exhaust manifolds?

Marcus

[lateapex911]

Originally posted by Marcus Miller@Sep 5 2005, 05:31 PM
Based on the ARRC lap times form last year, it loks like we need to pick up 4 seconds, which seems extremely difficult, or lose a second.

we could make the fast guys run on 6" rims and add a few pounds..

To lose a second per lap, maybe I'm way off base, but I think the 6 inch wide wheels would do it; beyond that, maybe restrict the cars to only using stock exhaust manifolds?

Marcus

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Well, THAT would do it, but the concept scares me....I wonder if we could touch the Audis and Volvos on the straight!

Wouldn't that suck?? A backmarker in A, then a backmarker in B? LOL.