lateapex911
Super Moderator
In a relatively short period, you may be a believer
IS300 in ITS?
- Thread starter SPiFF
- Start date
In a relatively short period, you may be a believer
Andy Bettencourt
Super Moderator
You are right Rob. But the fast and developed Mazda's and 240Z's can't compete with the fast and well developed E36's. Nick's RX-7 has never been faster, so it will be interesting to see how well he can do at RA in terms of laps. Just more data really.
When you compare apples to apples, the on-track performance of the E36 supports the 'process' that it is too light. Simple really.
You guys were able to beat Nick's car without the HP your cars were capable of. How do you define an 'overdog'?
AB
chuck baader
New member
I have an idea 
Let's take the fastest BMW, 7, and Z and have a round robin race. Let each driver race his own car first, one of the other cars second and third with practice sessions and/or maintenance sessions between. That way we can remove the largest variable in the whole discussion 
I submit that all the cars would be extremely equal 
Another thought...how many of you have actually built your car? When the interior and sound deadning is removed, a BMW can be under weight beyond that allowed to be added in the front passenger foot well. Adding weight as some have proposed will necessitate reinstallation of the interior! I, for one, would not like all that flamable vinyl around me. Chuck
Let's take the fastest BMW, 7, and Z and have a round robin race. Let each driver race his own car first, one of the other cars second and third with practice sessions and/or maintenance sessions between. That way we can remove the largest variable in the whole discussion I submit that all the cars would be extremely equal Another thought...how many of you have actually built your car? When the interior and sound deadning is removed, a BMW can be under weight beyond that allowed to be added in the front passenger foot well. Adding weight as some have proposed will necessitate reinstallation of the interior! I, for one, would not like all that flamable vinyl around me. Chuck
Banzai240
New member
NOT true... The ITAC recommended and the CRB approved ballast rule changes last year... There is no longer a 100lbs limit... New rule simply states "Ballast may be used", then defines segment size and location...
Cars wouldn't have to change, just add more lead...
I don't see how someone can say that the cars would be "equal", when on has such a clear wt/hp advantage, not to mention GOBS more torque as well... Simply doesn't add up, nor does the data support such a claim... Especially not top vs top...
its66
New member
<HIJACK>
While I'm not an engineer, I question the validity of trying to assign a flat percentage number to drivetrain loss. Wouldn't it take the same amount of force (torque-HP) to turn a given drivetrain at a given RPM level? If you measure flywheel HP and RWHP for, let's say a 405 hp Z06, then swap a lower HP engine into the same chassis, wouldn't the percentage loss change?
example
405 flywheel HP
340 RWHP
net 65 hp used to turn the drivetrain 5900 rpm
16% loss
now, swap in a..um mythical e36 engine
let's assume it is completely stock with the factory 189 flywheel HP
Which way would you esitmate the RWHP?
189 - 65 = 124
or
189 x .84 = 158.76
I know this is different than conventional wisdom, but turning a shaft, axle, wheel, etc. is work. Turning it a certain RPM is a measurable amount of work. Horsepower is a measure of work. That amount of work shouldn't change simply because there is a bigger "horse" doing the work.
Just thinking out loud.
<HIJACK OFF>
mlytle
New member
because it isn't just about weight and hp. it is also about all the other qualities of the car too...brakes, suspension, cg, wheelbase, mass, front vs. rear drive, etc, etc, etc. all these cars are inherently different and will never perform the same in all parts of the track. wt/hp is just ONE factor. "equal" is the ability to finish together at the end of a race, not the end of a straight. we aren't drag racers, thankfully!
Ron Earp
Administrator
<HIJACK ON>
Jim, don't worry about conventional wisdom, I think you are right as well. We've discussed it quite a bit on www.gt40s.com too and I along with some powertrain engineers from GM that are members did some heat calculations. Using flat percentages cannot be correct (but can be close), especially with some of the high hp motors we use with our transaxles because the heat dissipation becomes a real problem - 1hp = 746W and you end up with just too much heat to get rid of.
I generally use the dyno just for changes, the absolute number doesn't mean a lot to me. The 11% that came from that Ford SAE paper was not precisely what Ford wrote, they wrote the parasitic losses as a kW figure, which one can convert to hp, and then to a fraction of what the motor puts out. It was noteworthy because they had acheived low losses with a heavy truck driveline.
<HIJACK OFF>
Sounds like some weight is coming for the BMWs. Maybe that will bring some parity back to the SE in ITS at the long tracks in the region. That old weight/hp arguement doesn't work too well because it simply ignores that engines' torque curve and the area under that curve is considerably more than other cars in the class.
I just don't think it is arguable about the weight - the car weighs much less than street trim and it is the only car to my knowledge that is like that. 10% less than street weight is a nice classification - I wish I had that on my JH. I'm classed at 2240, most JH street cars with all the stuff weigh in at 2170-2200. If I could have 10% off my street weight of around 2200lbs I'd be at 1980lbs. I think at that weight with a 2L DOHC 140 hp stock 4 banger, a lot of folks would suddenly become interested in JHs.
Just like they are with BMWs at 2850lbs and 175 stock hp.
Ron
Banzai240
New member
Originally posted by mlytle@Sep 16 2005, 12:34 PM
because it isn't just about weight and hp. it is also about all the other qualities of the car too...brakes, suspension, cg, wheelbase, mass, front vs. rear drive, etc, etc, etc. all these cars are inherently different and will never perform the same in all parts of the track. wt/hp is just ONE factor. "equal" is the ability to finish together at the end of a race, not the end of a straight. we aren't drag racers, thankfully!
[snapback]60371[/snapback]
You are preaching to the choir... I feel like you guys aren't paying attention to what I've been trying to say... Maybe I'm just not being clear, or maybe over 7-pages of post the explanations blur together...
As I've stated before, wt/hp ratio is a STARTING point... That is where the BASE weight comes from... From there, the real speculation begins, because that is when you start looking at suspension, drive-train, brakes, tranny-ratios, etc...
In this case, have you MEASURED the brakes on an BMW??? They are HUGE... Additionally, certain makes tend to have advantages in other areas... The BMWs almost always have very good tranny ratios, and the suspension on this car is really good... All of this in comparison, I might add, to the "control" cars in the class.
In other words, we try to establish a weight based on a wt/hp ratio, then we add or subtract weight for the "adders" by seeing how the subject car compares to the other cars in the class...
Now, in this PARTICULAR case, I can find no compelling argument to support the idea that the car is correctly classified, when it's BASE weight should be anywhere from 3100-3250lbs or so (depending on whose HP figures you use...), and THEN you factor in a close ratio tranny, huge brakes, etc... keeping in mind, of course, that the extra weight will negate certain factors, of course...
You see... believe it or not, we actually DO think about all these things before making recomendation... Whether you guys want to believe it or not, the ITAC is doing it's darndest to work in the best interests of Improved Touring as a class... We have no interest and nothing to gain by singling out specific makes/models/etc...
bldn10
New member
"Looking over some past ITS Road Atlanta results I can't find ANY car with ANY driver under a 1:41 in ITS. Not even Chet in his old 240."
Looking through my far-from-complete past RA results I found the following under 1:41:
ARRC 2004 - Chet 1:40.936 BMW
ARRC 2004 qual. - Ed York 1:40.890 BMW
ARRC 2001 qual. - Sylvain Tremblay 1:40.372 RX-7
Looking through my far-from-complete past RA results I found the following under 1:41:
ARRC 2004 - Chet 1:40.936 BMW
ARRC 2004 qual. - Ed York 1:40.890 BMW
ARRC 2001 qual. - Sylvain Tremblay 1:40.372 RX-7
Catch22
New member
Oh boo hoo.
I'm mailing you a box of tissues.
Try getting an Integra GSR up to 2700lbs (classed at 2575 in Honda Challenge and Grand Am and thats about what it weighs with an 8 point cage and a 180lb driver).
Or how about a 2900lb Prelude. I think the OPM car has a John Deere riding mower welded into the hatch.
Try again. There are already people out there adding 150+ pounds to get to minimum weight. So the poor BMW guys can do it too.
And all this stuff about who can win where and ITA cars being faster than ITS cars is just useless. You have to look at the BIG events and what happens when the competition is all there.
That guy you are talking about that murders most of ITS at Lime Rock on a regional weekend DOES NOT do so at the ARRC. He's very fast to be sure, but 2 to 3 seconds behind the ITS leaders at that race.
The ITA track record at VIR is now 6 seconds off the ITS record.
Bottom line... The TOP, fully prepared, hot shoed E36s are going to whip up on the top, fully prepped, hot shoed RX7s, 240s, and Integras all day long. I don't need a round robin tournament, I see it on every race weekend.
RacerBowie
New member
Originally posted by Z3_GoCar@Sep 16 2005, 12:27 PM
Just remember if you slow the BMW's down too much for the South East we'll have ITA cars finishing AHEAD of ITS cars in SoPac and SFR. All season long we've has ITA Mazda's/Acura's finishing 2nd thru 10th in ITS, even spec Miata's are beating ITS Mazda's. To me that sounds like someone needs to work on their car and develop it's potential not complain that BMW's are just better.
Just a thought but how much sound deading material was in your Jensen? I bet I've got more sound proofing in my Z3. Actually the Z3 is alot like your JH, right down to the 138hp 4pot. So should we be adding 500lbs to match the Z3, or are you just fine in ITS?
James
[snapback]60389[/snapback]
...and when those very same top-level spec miatas come to Road Atlanta, they are ALWAYS slower than my ITA Miata, and I am about 1.4 seconds or so off the fastest guys in ITA, who are another 3 seconds off the ITS BMWs. (Spec Miata lap record at Road Atlanta is 1:45.3, ITA Record is a 1:43.3, ITS record is a 1:40.2)
Maybe the ITS cars in your region just suck? We have the closest thing IT has to a national championship in our region (ATL), so we see a pretty darn good representation of no-compromises cars. If SMs are beating A cars, the A cars aren't developed or driven well. If SMs are beating S cars, the S cars SUCK!
Bowie
ITA Miata
Ron Earp
Administrator
Originally posted by Z3_GoCar@Sep 16 2005, 04:27 PM
Just a thought but how much sound deading material was in your Jensen? I bet I've got more sound proofing in my Z3. Actually the Z3 is alot like your JH, right down to the 138hp 4pot. So should we be adding 500lbs to match the Z3, or are you just fine in ITS?
James
[snapback]60389[/snapback]
Ummmmm, like none. You've got more sound proofing in your car than I have metal in mine. And the metal is so thin I think I'm going to fly through the floor pan when I hop in. In fact, your sound proofing probably weighs more than my floor pans.
So, no, the Z3 is not a lot like a JH - your car won't fall apart and doesn't have to be treated like it is made from Renoylds aluminum wrap. Plus, you don't have the joy of working on a Colin Chapman (aka The Master of Cheap) designed engine, man, what fun! :angry: As for being fine in ITS, well, we don't know! Haven't driven the car, hell, haven't started the car due to bad head work that I was foolish enough not to check. Idiot I am :angry: . But, I'll be fine in ITS, I can feel it. Use The Force Luke.
JeffYoung
New member
JH and Z3 the same! Ha.....uh..no....you got drums out back? trailing arms that aren't even as thick as my forearm? tin pan floor pan that BENDS when you put a heavy tool on it?
The spec weight is probably necessary for the car to be in ITS. If it was classed lighter, you're looking at a car that has 170-80 hp potential at 2000 lbs. Probably not right either.
But it's not going to be easy to get the car to 2200. Right now, pushing it around, it FEELs less than 2000 but who knows.
Back to Bimmers..yoo hoo...Bimmer brigade...why is the car at 2850?
The spec weight is probably necessary for the car to be in ITS. If it was classed lighter, you're looking at a car that has 170-80 hp potential at 2000 lbs. Probably not right either.
But it's not going to be easy to get the car to 2200. Right now, pushing it around, it FEELs less than 2000 but who knows.
Back to Bimmers..yoo hoo...Bimmer brigade...why is the car at 2850?
Bruce Shafer
New member
To my knowledge nobody on this board spec'd the car when it was listed. Apparently we were just lucky enough to catch a competitive car when reading the GCR for entertainment. Also remember something to the effect of no cars being guaranteed to be competitive.
You guys might have a winner too with the JH and TR8. Good luck.
Ron Earp
Administrator
Originally posted by Bruce Shafer@Sep 16 2005, 05:30 PM
You guys might have a winner too with the JH and TR8. Good luck.
[snapback]60394[/snapback]
Next year is my Rookie year as a driver and the JH will be running. Jeff's TR8 seems to be solved and I think she'll be a runner again. Prepare to feel the wrath of the British Empire!
Didn't spec the car, what does that mean? The car is specified if it is in the GCR. And, it used to weigh more too, wasn't it originally at 2950?
R
Bruce Shafer
New member
I meant none of us had anything to do with how the car was written up in the GCR (at least I haven't heard that rumor yet).
As I remember correctly, it was originally at 2850, then there was an attempt to raise it to 2950. I believe somebody then read the current rules at the time to the CB and the attempt was rescinded. That is my take on what went down.
JeffYoung
New member
Bruce, I've probably been too beligerent on this issue. Let me try something more constructive.
Would you guys (the Bimmer crowd) be ok with no restrictor and 3050 lb race weight?
That seems like the correct, fair result to me. I frankly think the restrictor was a bad idea.
Would you guys (the Bimmer crowd) be ok with no restrictor and 3050 lb race weight?
That seems like the correct, fair result to me. I frankly think the restrictor was a bad idea.