ITB Sentra - WTF?

ITB sentra

Hello everyone

It has been a long time since my last visit to IT forums and I have been racing a ga16de for a while now in my case I was allowed to compete in ITA class with 2250 weight rule since we dint have a any other car in the field that falls under the criteria of the SCCA ITB Class but now we are starting to see more new comers that actually belonged to ITB but were still allowed to race under ITA class for quorum purposes however the local directors have decided to open the ITB class since the field is growing and is allowing every class to have a fare share of cars as per SCCA standards in my case I can choose for 2013 season to stay in ITA with the SR20DE engine transmition currently sitting in my garage or to try luck in ITB with my actual 1.6 GA16DE and last time I looked the rule book it mentions that the little GA in the B13 chassis has to weight more than 2500 pounds! This has to be a mistake with just 110 HP since there are other cars with the same or more power that has less weight handicap.

The GA16 is a great bulletproof engine but it has no ICE CREAM CONE CHANCE IN HELL with so much weight and as it is right know I rather go to ITA and have a competitive car and one of the reasons I’m leaving the ITB dream is the weight that has been imposed on the car I think SCCA can do something about that since the B13 chassis is a cheap easy to find parts car that fits within the purpose of low cost ITB purpose/criteria.
 
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ramoncito89 said:
Hello everyone

It has been a long time since my last visit to IT forums and I have been racing a ga16de for a while now in my case I was allowed to compete in ITA class with 2250 weight rule since we dint have a any other car in the field that falls under the criteria of the SCCA ITB Class but now we are starting to see more new comers that actually belonged to ITB but were still allowed to race under ITA class for quorum purposes however the local directors have decided to open the ITB class since the field is growing and is allowing every class to have a fare share of cars as per SCCA standards in my case I can choose for 2013 season to stay in ITA with the SR20DE engine transmition currently sitting in my garage or to try luck in ITB with my actual 1.6 GA16DE and last time I looked the rule book it mentions that the little GA in the B13 chassis has to weight more than 2500 pounds! This has to be a mistake with just 110 HP since there are other cars with the same or more power that has less weight handicap.

The GA16 is a great bulletproof engine but it has no ICE CREAM CONE CHANCE IN HELL with so much weight and as it is right know I rather go to ITA and have a competitive car and one of the reasons I’m leaving the ITB dream is the weight that has been imposed on the car I think SCCA can do something about that since the B13 chassis is a cheap easy to find parts car that fits within the purpose of low cost ITB purpose/criteria.
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And thus the original point of the thread. The ITAC/CRB aren't going to adjust anything without a member request. Write the CRB and request the weight be adjusted; it sounds like there is an excellent chance it would be.
 
erlrich said:
Ummmm.... no.... I was actually waiting for the the ITAC/CRB to announce they were going to quit using the 30% multiplier ;)

...and if you believe that....
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Check the october fastrack, we (ITAC) removed the 30% min rule in ITB.

So the sentra "should" be 2290 in B (25%) or 2385 (30%) unless there's data I don't know about. Id default to 2290 myself but even 2385 is a break from current classing.
 
Are all the weight tables for ITB be corrected in the 2013 GCR Book? Or must each car be requested to be reviewed separately?
 
At this point, ITB is being reviewed. Currently, no changes can be promised. The data itself is still being collected. It will not be ready within the next few months. Currently, we have no ETA, and even once the data is all run, we need to make recommendations to the CRB, and they have to approve said recommendations.

I cannot promise anything at this point. At the same time, I'm not sure a specific request would speed the process for a single car either. I'd submit it. Worst you can get is a "we're working on it" response (well, worse would be... well, you know).
 
and if you can supply technical information to help fill our shelves, we appreciate it. even if it's just information on the mechanicals and nothing about output potential and all that.

but yeah - what Matt said.
 
As far as I understand the new rule only affects DOHC engines. Can anyone share with us what the new formula be?
To have an example lets use the 1985-87 Toyota Corolla GTS
1.6L
DOHC
112hp
RWD
 
There is no "new" formula. The only change in the process has been to remove the "default to 30% for multivalve cars in ITB/C" and return those cars to the standard process of 25% when they are reprocessed or newly classified. The same overrides can be made if a 75% majority of the committee feels that there is a need to alter the process for a particular architecture.

So according to the info you've given:

112hp x 1.25 (25% default multiplier) = 140 (anticipated "process" crank hp in IT trim)
140 x 17 (lb/hp multiplier for all ITB ) = 2380 lb. (weight prior to adders/subtractors)

It appears the car is classified correctly at 2380 in the current GCR.

The FX-16 FWD version also gets a 2% subtractor for FWD (part of the process), which equals 2332.4, which rounds down to 2330 (nearest 5). It also appears correct.

Another factor is in play here, however. Last month, the CRB approved a weight reduction for the MR2, based on a recommendation made by the ITAC. This reduction centered around evidence that the 4A-GE engine did not respond ideally to IT modifications. This was supported with loads of technical evidence from the MR2 community. This evidence was reviewed by the ITAC, which, after MUCH discussion and further gathering of information, determined that an adjustment to the default multiplier would compensate for the documented discrepancy. After a confidence vote, the ITAC recommendation was forwarded with all supporting information to the CRB (as a side note, CRB liasons monitored the ITAC discussions, so more than just basic technical background was available to the CRB ). The CRB reviewed the recommendation and supporting information, and decided to approve a weight based on a 20% multiplier, yeilding the weight that is currently listed.

The issue is this, and as of this point is not yet resolved. This reduction was based on the 4A-GE engine, which is also in the Corolla GTS and the FX-16 in ITB. I believe the same powerplant is in one or two ITA cars as well, correct?

At this point, this is part of a larger issue of inconsistency in ITB. Any oversight in this situation was certainly not intentional. The large issue itself raises a lot of questions, and will be one that the ITAC will be spending lot of time on to determine the best course of action.
 
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Not having looked at the FT, I would have expected both the GTS and FX-16 to have been changed using the same multiplier as the MR2.

I do not believe that the powerplant is used in anything in ITA. IIRC, the 101hp 12A, the 108hp Si's and the 116hp 1.6 Miata are the lowest HP's in ITA.
 
ShelbyRacer said:
There is no "new" formula. The only change in the process has been to remove the "default to 30% for multivalve cars in ITB/C" and return those cars to the standard process of 25% when they are reprocessed or newly classified. The same overrides can be made if a 75% majority of the committee feels that there is a need to alter the process for a particular architecture.

So according to the info you've given:

112hp x 1.25 (25% default multiplier) = 140 (anticipated "process" crank hp in IT trim)
140 x 17 (lb/hp multiplier for all ITB ) = 2380 lb. (weight prior to adders/subtractors)

It appears the car is classified correctly at 2380 in the current GCR.

The FX-16 FWD version also gets a 2% subtractor for FWD (part of the process), which equals 2332.4, which rounds down to 2330 (nearest 5). It also appears correct.

Another factor is in play here, however. Last month, the CRB approved a weight reduction for the MR2, based on a recommendation made by the ITAC. This reduction centered around evidence that the 4A-GE engine did not respond ideally to IT modifications. This was supported with loads of technical evidence from the MR2 community. This evidence was reviewed by the ITAC, which, after MUCH discussion and further gathering of information, determined that an adjustment to the default multiplier would compensate for the documented discrepancy. After a confidence vote, the ITAC recommendation was forwarded with all supporting information to the CRB (as a side note, CRB liasons monitored the ITAC discussions, so more than just basic technical background was available to the CRB ). The CRB reviewed the recommendation and supporting information, and decided to approve a weight based on a 20% multiplier, yeilding the weight that is currently listed.

The issue is this, and as of this point is not yet resolved. This reduction was based on the 4A-GE engine, which is also in the Corolla GTS and the FX-16 in ITB. I believe the same powerplant is in one or two ITA cars as well, correct?

At this point, this is part of a larger issue of inconsistency in ITB. Any oversight in this situation was certainly not intentional. The large issue itself raises a lot of questions, and will be one that the ITAC will be spending lot of time on to determine the best course of action.
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Thanks ShelbyRacer;
Not to keep banging the same drum, but could you also do the math for the 1985-87 Toyota Corolla SR5
1.6L
SOHC
70hp
RWD


Thanks,
 
The math goes hp*multiplier*class weight number and modifiers where appropriate.

For ITB the class weight # is 17. USDM 4A-C engines were rated at 90hp, not 70 as in your post.

90*1.25*17=1912.5 rounds to 1915
 
Could someone let us know the different formulas for all IT categories including platforms(FWD, RWD, AWD, Mid engine, etc)?
 
AE86ITA said:
Could someone let us know the different formulas for all IT categories including platforms(FWD, RWD, AWD, Mid engine, etc)?
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From the ITAC manual:
The power-to-weight ratio targets for each class are as follows:
ITR: 11.25 lbs/hp
ITS: 12.9 lbs/hp
ITA: 14.5 lbs/hp
ITB: 17 lbs/hp
ITC: 18.84 lbs/hp
The horsepower used for the calculation is the most complicated part of the process. It can be determined by one of two methods: "published horsepower" or "known horsepower."
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and:

Then, adders and subtractors are applied. They are as follows:
  • FWD cars get a percentage-based subtractor: 6% for ITR, 5.5% for ITS, 2% for ITA and ITB, and 0% for ITC. Note that AWD cars should not get this adjustment.
  • Cars with double-wishbone suspension get a 50 lb. adder.
  • ITR cars with both FWD and front struts get -50 lb.
  • Live axle RWD cars in ITR get -50 lb.
  • Mid-engined (engine between driver and rear axle) cars get +50 lb.
  • Cars with abnormally small or large brakes for their class get -50 lb. or +50 lb.
  • Cars with excessively low or high engine displacements, or excessively high or low peak torque, can be adjusted up to the following limits. (For example, a very-high-displacement, very-high-torque car would get a max of +50 in ITB ). These are maximums, and this adder is not absolute. The ITAC should use its judgment about whether or not these cars are likely to accelerate slower or faster than an "average" car for the class. Note that rotaries should be considered small displacement engines.
Class Normal displacement range (liters) Large displacement / high torque Small displacement / low torque
ITR 2.2 - 3.8 +150 lbs -100 lbs
ITS 2.1 - 2.9 +100 lbs -50 lbs
ITA 1.5 - 2.5 +100 lbs -50 lbs
ITB 1.7 - 2.3 +50 lbs -0 lbs
ITC 1.5 - 1.7 +50 lbs -0 lbs
Click to expand...
 
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Andy Bettencourt said:
I do not believe that the powerplant is used in anything in ITA. IIRC, the 101hp 12A, the 108hp Si's and the 116hp 1.6 Miata are the lowest HP's in ITA.
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I was thinking the 88-92 Corolla GTS (FWD AE92? style), but that would've been 88-89. I *think* the 90-92 got the non-TVIS uprated version (something like 130-some hp).
 
AE86ITA said:
Could someone let us know the different formulas for all IT categories including platforms(FWD, RWD, AWD, Mid engine, etc)?
Click to expand...

What Earl said, plus the default HP multiplier is 1.25 (25% gain over stock).

A few years ago, this entire process was made available to the membership. It's in a link called the ITAC Operation Manual in a sticky at the top of this (Rules and Regs) forum. Here's a link to it as well.
 
please note that the link above does not contain the updates posted in the fastrack. the updated document should be on the website soon.
 
Andy Bettencourt said:
Not having looked at the FT, I would have expected both the GTS and FX-16 to have been changed using the same multiplier as the MR2.

I do not believe that the powerplant is used in anything in ITA. IIRC, the 101hp 12A, the 108hp Si's and the 116hp 1.6 Miata are the lowest HP's in ITA.
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In the last Fastrack someone suggested that all 4AG powered cars be adjusted as per MR2. The response was to read letter(technical bulletin) #6953. Can someone explain if it will be done or someone must start the same process all over again for all 4AG powered cars(excluding the MR2)?


Thanks,
 
AE86ITA said:
In the last Fastrack someone suggested that all 4AG powered cars be adjusted as per MR2. The response was to read letter(technical bulletin) #6953. Can someone explain if it will be done or someone must start the same process all over again for all 4AG powered cars(excluding the MR2)?


Thanks,
Click to expand...

write a letter, it can't hurt, though I do intend to address it ASAP.
 
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