Teach me about ITR 325's

[robits325is]

The 1986-1988 NA RX-7's all had 146 stock hp. The 89-91 NA RX-7's all had 160 stock hp - regardless of model. They are many mechanical differences in the motors. Nobody runs a 146hp motor in ITS.

If the 86 is 146hp and the 91 is 160hp then why are they on the same spec line?

[Greg Amy]

The 1986-1988 NA RX-7's all had 146 stock hp. The 89-91 NA RX-7's all had 160 stock hp - regardless of model. They are many mechanical differences in the motors. Nobody runs a 146hp motor in ITS.

And, if they were split out, then they'd also not have the bigger brakes, the rear wing, and the trick 5th gear, yes? Their only "parts bin" advantage versus the current ITS rocket is the lack of power steering.

Honestly, at the right weight, I think that would be a fine addition to ITA. And, it would give members the opportunity to race the 2nd-gen car competitively with minimal changes. A win-win as far as I'm concerned, and a great illustration of why it's a bad idea to put significantly different cars on the same spec line.

If the 86 is 146hp and the 91 is 160hp then why are they on the same spec line?

Same reason as the ITA 1.8L Miatas, and the E36s, and several other cars are: someone thought it was a good idea, that it would make for simplicity. In the end all it does is force preparation to the highest level in order to be competitive.

And that's not really what Improved Touring is supposed to be about.

GA

[Knestis]

Seems to me that a pretty good argument can be made in both of these examples (2nd-gen RX7 and the e36 325) to have multiple spec lines. But the simplicity argument has merit, too. Looking at first principles, which way do we think the scales tip? I ask because others might agree with Greg's contention of "what IT is supposed to be about..."

(FWIW, I personally tend to agree with his thesis, even if ITAC practice typically leans the other direction.)

KK

[JeffYoung]

Anybody have any idea how many cars have different hp ratings on the same spec line?

I tried to think of others besides the ITA Miata and RX7, and can think of only one. Mine -- 133 for the carb car, 137 for FI.

Just trying to understand how big of a universe we are dealing with.

[Jeremy Billiel]

Anybody have any idea how many cars have different hp ratings on the same spec line?

I tried to think of others besides the ITA Miata and RX7, and can think of only one. Mine -- 133 for the carb car, 137 for FI.

Just trying to understand how big of a universe we are dealing with.

I will have to go back and look, but the 2nd gen Interga in ITA had various hp numbers, tranny ratios, etc.

[shwah]

Since the 'best' option is considered when classing the car, I don't see why it matters if the weaker sibilngs are on the same spec line.

Simple is better IMO.

[robits325is]

Since the 'best' option is considered when classing the car, I don't see why it matters if the weaker sibilngs are on the same spec line.

Simple is better IMO.

The only problem with simple is that Frankenstein cars are created that exceed the classified model. The sum of the parts becomes greater than intended and an over dog is potentially created.

[Gary L]

Anybody have any idea how many cars have different hp ratings on the same spec line?

I tried to think of others besides the ITA Miata and RX7, and can think of only one. Mine -- 133 for the carb car, 137 for FI.

Just trying to understand how big of a universe we are dealing with.

I would think the ITB Volvo 140 series might be the poster child for this situation. Six model years are covered on one line entry. All six have the same basic engine, but the listing encompasses three factory engine designators (B20B, B20E, B20F), two different dual carb setups, two different Bosch injection systems, two short blocks and two heads. There is approximately 15% horsepower differential across the bunch.

The chassis for all six model years are essentially the same, but everyone that builds one of these simply uses the '71 B20E engine long block assembly and matching Bosch D-Jet injection. That particular engine is singularly the most powerful of the bunch, before and after IT tweaks. Bottom line - everyone ends up with what is essentially a '71 142E.

[JeffYoung]

Gary, since you have a lot of experience wtih this, in your opinion, is that a good or a bad thing, to have six different model years with varying induction systems and power outputs on the same line?

Or would the lower power cars be better served on a different line in C?

The flip side is that having the option to build any 140 into an ITB 140E opens up the number of actual chassises available to you, correct?

Interested in your thoughts, because I agree, that car looks like the poster child for this "issue" (if it is one).

I would think the ITB Volvo 140 series might be the poster child for this situation. Six model years are covered on one line entry. All six have the same basic engine, but the listing encompasses three factory engine designators (B20B, B20E, B20F), two different dual carb setups, two different Bosch injection systems, two short blocks and two heads. There is approximately 15% horsepower differential across the bunch.

The chassis for all six model years are essentially the same, but everyone that builds one of these simply uses the '71 B20E engine long block assembly and matching Bosch D-Jet injection. That particular engine is singularly the most powerful of the bunch, before and after IT tweaks. Bottom line - everyone ends up with what is essentially a '71 142E.

[Andy Bettencourt]

And, if they were split out, then they'd also not have the bigger brakes, the rear wing, and the trick 5th gear, yes? Their only "parts bin" advantage versus the current ITS rocket is the lack of power steering.

Honestly, at the right weight, I think that would be a fine addition to ITA. And, it would give members the opportunity to race the 2nd-gen car competitively with minimal changes. A win-win as far as I'm concerned, and a great illustration of why it's a bad idea to put significantly different cars on the same spec line.


Same reason as the ITA 1.8L Miatas, and the E36s, and several other cars are: someone thought it was a good idea, that it would make for simplicity. In the end all it does is force preparation to the highest level in order to be competitive.

And that's not really what Improved Touring is supposed to be about.

GA

This is a very interesting discussion and it really does follow the principles of IT. Breaking cars out and giving people more options is good.

For the record on the RX-7's: Many of the parts you see on ITS cars are NOT rare. The brakes also were available on the 86-88 cars as was the rear wing. The GXL and GTU were very common cars that had these items. There was no aluminum hood or 'better' 5th gear on any of the 86-88 cars as far as the documentation I have shows. The SE of that gen was a 4-lug, smaller brake car and was very entry level. It was not nearly as popular as the 3-4 other models.

It would be real interesting to have a 146hp S4 2nd gen car in ITA. If you extrapolate the power gains the S5 gets, I bet it could make 155whp (~30% gains) and about 125ftlbs. Around 2750lbs in ITA would make it interesting. Not my first choice, but certainly an option. I have never seen anyone 'IT-ize' the 146hp lump. The rotors have less compression.