Race Car Tech Discuss anything related to road racing and auto X.

Utlimate RX autocrosser

Old 07-26-05, 12:54 PM
  #1  
More Mazdas than Sense
5 Year Member
Thread Starter
 
Feds's Avatar
 
Join Date: Aug 2003
Location: Sunny Downtown Fenwick
Posts: 2,168
Likes: 0
Received 0 Likes on 0 Posts
Utlimate RX autocrosser

O.k., a little thought experiment...

You have in front of you a first gen RX-7, unlimited tools, and $10,000. Your mission is to make the ultimate RX-7 autocross car. No rules, no limits. What do you do?

Engine?
Trans?
Rearend?
Wheels/tires?
Suspension?
Feds is offline  
Old 07-26-05, 01:07 PM
  #2  
www.lms-efi.com
iTrader: (27)
 
C. Ludwig's Avatar
 
Join Date: Mar 2001
Location: Floyds Knobs. IN
Posts: 5,112
Received 30 Likes on 23 Posts
Ditch the 1st Gen and start over with a better platform. Sorry, I'm just honest.
C. Ludwig is offline  
Old 07-26-05, 01:17 PM
  #3  
Banned. I got OWNED!!!
 
christaylor's Avatar
 
Join Date: Mar 2003
Location: Austin, Texas
Posts: 1,546
Likes: 0
Received 0 Likes on 0 Posts
If it weren't for the title, I'd agree with Chris.

But I don't autocross, so I don't know the answer.
christaylor is offline  
Old 07-26-05, 01:34 PM
  #4  
More Mazdas than Sense
5 Year Member
Thread Starter
 
Feds's Avatar
 
Join Date: Aug 2003
Location: Sunny Downtown Fenwick
Posts: 2,168
Likes: 0
Received 0 Likes on 0 Posts
Alright, smartassing aside, I know that it is not THE platform to have, but it's part of the deal.

If it helps, it's not real money being spent. Just a thought experiment.
Feds is offline  
Old 07-26-05, 01:53 PM
  #5  
Blood, Sweat and Rotors
iTrader: (1)
 
DriveFast7's Avatar
 
Join Date: Aug 2001
Location: California
Posts: 3,733
Received 0 Likes on 0 Posts
13b turbo
slicks
fiberglass
lexan
cage

BP class?
DriveFast7 is offline  
Old 07-26-05, 02:01 PM
  #6  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Um, build a car like mine Honestly the 2nd gen platform has won 6 or 8 national championships in FP, and BP. Those cars were like mine, but half the power. I have NO lag in my current set-up(PT67 .81 P trim), although I would use a slightly smaller turbo hotside, like a .70 divided, instead of a .81 un-divided. Get a GTU shell, do a TII conversion, and widebody, then bolt a TO4R with a .70 hotside .70 compressor to it, viola BP national champ(Oh, and you'll need a driver In terms of the widebody, just prep it for thye flares, but skip them to keep cost, and weight down(if allowed to have exposed tires in BP). Carl
Carl Byck is offline  
Old 07-26-05, 02:03 PM
  #7  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Now, since you are using a first gen, Buy an old GTU/GT2/GT3 1st gen, turbo it, and go play
Carl Byck is offline  
Old 07-26-05, 02:24 PM
  #8  
More Mazdas than Sense
5 Year Member
Thread Starter
 
Feds's Avatar
 
Join Date: Aug 2003
Location: Sunny Downtown Fenwick
Posts: 2,168
Likes: 0
Received 0 Likes on 0 Posts
Thanks!

There is a possibility that the car will be a 2nd gen, not that this is anything other than a thought experiment

Where can I find more detailed spec on your car, Carl?

Just to make sure this thread stays interesting, would I be better of with, say, an LS1?
Feds is offline  
Old 07-26-05, 02:32 PM
  #9  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Feds
Thanks!

There is a possibility that the car will be a 2nd gen, not that this is anything other than a thought experiment

Where can I find more detailed spec on your car, Carl?

Just to make sure this thread stays interesting, would I be better of with, say, an LS1?
If you like slow cars I am making more than you will make with an LS1, uless you dump sick amounts of cash. My car, and dynos are linked on my thread "500+hp... ready to sort" When you go to the dynos doubly click on them, or any other photos. Basicly 480/[email protected], 506/[email protected], way rich, and relatively conservative tune.
Carl Byck is offline  
Old 07-26-05, 03:00 PM
  #10  
Rotary Freak
iTrader: (10)
 
Join Date: Mar 2001
Location: San Francisco, CA
Posts: 2,056
Likes: 0
Received 3 Likes on 3 Posts
The LS1 will completely screw up your handling (see sig) .... Plus on 91 octane I only make 500hp with about $3500 in upgraded parts into a stock LS1 shortblock.

Ahem....
gnx7 is offline  
Old 07-26-05, 03:06 PM
  #11  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Mark, See you at the track Saturday right??? Never said It would screw up handling, your sig says 439, not 500+. My motor can be had for ~900.00-1200.00. But enough of this, give me one weekend at the track to sort the car(one weekend), and I'll meet you at Thunderhill on 8/18 for the ultimate **** talkers challenge. BTW, you don't have to buddy up wih the editor to get into this one

PS all of the above is meant in fun, nothing more(yea right)
Carl Byck is offline  
Old 07-26-05, 03:53 PM
  #12  
Rotary Freak
iTrader: (10)
 
Join Date: Mar 2001
Location: San Francisco, CA
Posts: 2,056
Likes: 0
Received 3 Likes on 3 Posts
we are all car enthusiasts and talking sh*t is half the fun

My motor can be had for ~900.00-1200.00... don't forget to add turbo, exhaust manifold, downpipe, wg, fuel management, injectors, tuning, fuel pumps.... ohh yeah... did I mention tuning and having to fly guys in from around the nation to do it.

I'll be at Infineon Aug 6th.... I still have to learn my car as well. Coming from 140hp FC to a 500hp FD takes more than a few sessions at the track.
gnx7 is offline  
Old 07-26-05, 04:43 PM
  #13  
I'll blow it up real good
10 Year Member
iTrader: (1)
 
RX-Heven's Avatar
 
Join Date: May 2001
Location: San Francisco, CA
Posts: 2,390
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by gnx7
we are all car enthusiasts and talking sh*t is half the fun

My motor can be had for ~900.00-1200.00... don't forget to add
$2000 heads, $1500 headers & custom exhaust, $500 cam, fuel pump, transmission, pricey conversion kit that breaks, still needing someone else to tune it so it can idle @ 2000 rpm and still run to hot on a real track

btw, I'm riding in both of your cars at Infineon.

Carl, I also decided if you want my weekend you will need to let me drive your car at least one session over the weekend
Don't worry, I've turned 1:44's all day long at Infineon and gone through turn 10 @ 115+ (in Star Mazdas ).
RX-Heven is offline  
Old 07-26-05, 04:46 PM
  #14  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
I know what you mean, my car has never seen the track, or theb street. The suspension, turbo set-up, aero, and everything elso on the car is completely untried, never tested/proven etc. For all I know the brakes do not even workZ(note to self, test brakes before track day) The car may have too large a frontal opening, too small a hood opening, the rear bumper is more like a parachute than a bumper, you get the idea. I think it will take me a year to sort this car out, hopefully I do not crash it(very many times) before it runs right. So when did you bump the FD up to 500rwhp? How much does the car weigh? BTW, this is on topic, the LS1 FD has posted some very nice numbers to be sure. It's been a year and a half since I hit the track, building a car sure takes longer than buying one... On that topic, most of the really good Prepared class cars are Pro-built national caliber retired race cars, refitted for AX. Carl
Carl Byck is offline  
Old 07-26-05, 04:52 PM
  #15  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by RX-Heven
$2000 heads, $1500 headers & custom exhaust, $500 cam, fuel pump, transmission, pricey conversion kit that breaks, still needing someone else to tune it so it can idle @ 2000 rpm and still run to hot on a real track

btw, I'm riding in both of your cars at Infineon.

Carl, I also decided if you want my weekend you will need to let me drive your car at least one session over the weekend
Don't worry, I've turned 1:44's all day long at Infineon and gone through turn 10 @ 115+ (in Star Mazdas ).
remember I have not even driven the car myself yet, but,,,,

Sign a 30,000.00 promisory note(or the title to the 20B, and 10K), and you can have 3 laps, maybe more if the car is working right. Basicly, I do not know if anything will work, if it works right you are welcome to drive it a little, if it is behaving badly, or the handling/braking is unpredictable, then I'd be a little concerned. BTW I think NASA already made the change in registration
Carl Byck is offline  
Old 07-26-05, 04:53 PM
  #16  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
I'm starting a new thread so Feds can have his thread back
Carl Byck is offline  
Old 07-26-05, 06:33 PM
  #17  
More Mazdas than Sense
5 Year Member
Thread Starter
 
Feds's Avatar
 
Join Date: Aug 2003
Location: Sunny Downtown Fenwick
Posts: 2,168
Likes: 0
Received 0 Likes on 0 Posts
Thanks Carl...

So there is an aftermarket EMS in your car... I don't know if I will have time to tune. I guess that makes another restriction: Throw-it-together-and-flog-it prefered...

but if you could put together a parts list for your motor, I'd apreciate it.
Feds is offline  
Old 07-27-05, 10:00 AM
  #18  
All Motor
10 Year Member
iTrader: (2)
 
Icemastr's Avatar
 
Join Date: Mar 2003
Location: Redmond, WA
Posts: 1,605
Likes: 0
Received 0 Likes on 0 Posts
Step 1: Sell first gen RX-7.
Step 2: Buy STS 2 Prepped Miata for $4000-$5000
Step 3: Go to Evolution School 20 times
Step 4: Go to 40 autocross events each year
Step 5: Your 10,000 is gone before 1 year of racing, work a lot to make the rest to support 8 more years of racing
Step 6: Now any car that is setup right for a class becomes the ultimate autocross car when you hop in the drivers seat.

Autocross is entirely driver, I had Karl Coleman drive my car at an event not too long ago and he hopped in my nearly stock Miata on street tires and was 1.5 seconds off the fastest time during the NON-Stock half of the day. Thats with pretty competitive prepped SM2 Miatas and all sorts of stuff and he said my car was handling bad because he had to counter steer alot.
Icemastr is offline  
Old 07-27-05, 10:05 AM
  #19  
All Motor
10 Year Member
iTrader: (2)
 
Icemastr's Avatar
 
Join Date: Mar 2003
Location: Redmond, WA
Posts: 1,605
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Carl Byck
Um, build a car like mine Honestly the 2nd gen platform has won 6 or 8 national championships in FP, and BP. Those cars were like mine, but half the power. I have NO lag in my current set-up(PT67 .81 P trim), although I would use a slightly smaller turbo hotside, like a .70 divided, instead of a .81 un-divided. Get a GTU shell, do a TII conversion, and widebody, then bolt a TO4R with a .70 hotside .70 compressor to it, viola BP national champ(Oh, and you'll need a driver In terms of the widebody, just prep it for thye flares, but skip them to keep cost, and weight down(if allowed to have exposed tires in BP). Carl
Not sure if you are talking about Solo II classes or club racing classes but I have a feeling your car would not do so well on an autocross course.
Icemastr is offline  
Old 07-27-05, 10:39 AM
  #20  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Cool

Originally Posted by Icemastr
Not sure if you are talking about Solo II classes or club racing classes but I have a feeling your car would not do so well on an autocross course.
Not to sound to snappy, but you have NO CLUE as to what you are talking about. My suspension, car weight, and all other elements pertinent to whether my car would perform well at an AX are essentially identical to two cars who, between them have more than 8 national Solo II, and Pro Solo championships spanning almost ten years. The only difference really, is that my car makes more than double the power, it does so in a linear and completely predictable fashion. I have NO lag that is detectable when the car is driven as a mid size turbo should be, and I have twice the torque of the two cars that have already won nationals. That torque is flat from ~4500-8400rpm. I suppose the only other difference is that I figured out how to get one more inch of tire front and back under the car than my predecessors. So why don't you explain to the class how it is that you have arrived at this conclusion.... I am sure you took the time to follow the link to the page dedicated to my car, and I am sure you know more than the eight time national champion Solo drivers, so please take a moment to educate us. You do not post often in this section, perhaps you should vist more often so we can learn from you. Regards, Carl Byck

Last edited by Carl Byck; 07-27-05 at 11:07 AM.
Carl Byck is offline  
Old 07-27-05, 10:49 AM
  #21  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
BTW, the fact that someone has to "countersteer, means simply that they are over driving the car for its existing set-up, that is never the fast way around, so, obviously you cannot even comprehend what this man was trying to explain to you, and/or, most likely the guy thrashed your poorly set-up car because ther was nothing else worth doing with it. If it's all driver, then why do national champions bother to buy new cars???? why is each class generally dominated by one or two models? It takes both, without one or the other, you are an "also ran". What is it that you "instruct", maybe you can help us out on some of our questions regarding set-up. I have 16x11 slicks in front, and 16x13 out back, my suspension geometry is otherwise unchanged from stock, what will happen to my scrub radius? Thanks in advance for your knowledge, Carl
Carl Byck is offline  
Old 07-28-05, 02:50 PM
  #22  
Mad Man

 
Carl Byck's Avatar
 
Join Date: Jan 2002
Location: Big Island Hawaii
Posts: 2,758
Likes: 0
Received 0 Likes on 0 Posts
Where did you go Mr. Ice???
Carl Byck is offline  
Old 07-28-05, 03:06 PM
  #23  
I'll blow it up real good
10 Year Member
iTrader: (1)
 
RX-Heven's Avatar
 
Join Date: May 2001
Location: San Francisco, CA
Posts: 2,390
Likes: 0
Received 0 Likes on 0 Posts
Damn Carl, don't let anyone tell you your car sucks
RX-Heven is offline  
Old 07-28-05, 03:14 PM
  #24  
All Motor
10 Year Member
iTrader: (2)
 
Icemastr's Avatar
 
Join Date: Mar 2003
Location: Redmond, WA
Posts: 1,605
Likes: 0
Received 0 Likes on 0 Posts
Why was the person who drove my car having to countesteer? Because like I said the car wasnt handling properly, the car was setup decently but my alignment settings had become loose since that last time I had them done as I found out when recently having the car aligned, my toe on the passenger side rear tire was 1/16 out when previously the alignment had been set to 1/16 total toe in and was handling great a few weeks before when Karl drove it. I think this has to do with the bolts needing to be replaced which happens on Miatas. Karl is a good enough driver that he can hop in just about anything and push the car to the absoloute limit, the course was heavily biased in left turns which would cause the right rear to want to continue swinging out. Because he would push the car he would get right to the limit of the tires and the rear would begin to swing out just a bit too much he would give it a slight countersteer, to put the car back into line. If I am missing something or I am misinformed please explain as I am always learning. Autocrossing is all driver, why do they buy new cars? Because new cars come out and and classing is always changing so when one new cars become more dominant the people who race stock class especially buy those cars to be competitive nationally and in regional PAX classes. Not all classes have completely dominant cars but many do. Someone who is a great driver can hop in a car that is not the car to have in that class and beat a field of mediocre or even pretty good drivers. However when it comes down to national level competition in autocrossing the times are within hundreths if not thousands of each other and the slightest difference in a car can make the difference. I didn't specify why I didn't think your car might not be so competitive at autocrossing and maybe I should have. The thing that comes to my mind first is the turbo, although you have a great torque and horsepower curve this is not everything on the autocross course. Doing a quick dyno comparison between a dyno I found of your car, not sure what PSI it was at your peak HP was around 450 so I am sure you can push a bit more, your car was making 45HP less at 3400rpm, 20 less at 4000RPM,and 30HP more at 4500 RPM and 50-60 more the rest of the way up. With your 500hp graph you would probably be a bit over 100HP more from 5000RPM on up. I will say your engine makes power quick compared to other smaller turbos such as a GT35R graph I also compared where your car was making 50 more HP than the GT35R even at 3500RPM. This gives you a huge advantage on the track since you will probably never be below 4000rpm, however on an autocross course boost/throttle response then max torque across the powerband is most important. A FMIC, large piping, and a large turbo greatly effect this. You claim the car has almot zero lag, I have never driven your car so I don't know how the boost response is on the car but common sense and experience says that a bigger turbo is going to respond slower than a smaller one. I am sure you launch at a high enough RPM that you always have positive pressure once you start racing on the track except for when you are breaking and coming out of corners. I have seen and experienced throttle response with naturally asprirated and forced induction engines because my area of competition and interest lies in the SM2 class which has 3rd gen RX-7s, Z06s, and Miatas all as the main contenders. I have codriven and compared results of a few of the different setups, 450rwhp corvette, sequential twin turbo FD with slightly enlarged ports and upgraded turbos tuned for max torque and spool up, postive displacement supercharged 99 Miata, GT28R miata and T3 super 60 Miata. When you have 4 times the steering inputs or more of a road course and very tight boxes to power out of, the disadvantages of a turbo become painfully apparent a lot quicker then on a road course. Comparisons between FMIC and SMIC for the FD have found the amount of time it takes to fill up all the charge piping and the intercooler makes a substantial difference in times alone. There are a few more things I could point out but they are easily changed but the point is you built your car for the track, some of its features, brake pads, roll bar, larger turbo,larger porting (not sure what size your ports are), FMIC are all things that are not the best for an autocross course. As far as your suspension goes I am sure that is all set very well and could do very well on an autocross course, but is your car going to go out and be nationally competitive in a class? That would be my definition of an ultimate autocross car. I do not know what kind of cars there are in the class you would compete in since there is only one car in my region that I have seen regularily race in a prepared class. Autocrossing isn't quite so fun to me when there isn't anyone to compete against either. I could be wrong on the scrub radius since I don't know much about since have only raced stock classes until the past couple months where we can't change offset or rim width anyways but if your suspension geometry and wheel offset remain the same I think your scrub radius would stay the same.
Icemastr is offline  
Old 07-28-05, 03:50 PM
  #25  
Senior Member
 
Join Date: Jul 2003
Location: San Jose
Posts: 291
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Carl Byck
Not to sound to snappy, but you have NO CLUE as to what you are talking about. My suspension, car weight, and all other elements pertinent to whether my car would perform well at an AX are essentially identical to two cars who, between them have more than 8 national Solo II, and Pro Solo championships spanning almost ten years. ....Regards, Carl Byck
I wouldn't be so sensitive Carl. You've obviously done alot of research and built a nice looking car. However, you might want to wait until actually autoxing the car before saying it is great. On paper your car might be the same or better than previously successful BP 2nd Gen cars, but you might find the major power you're making would need to be dialed back on a little autox course. Anyway, it would be nice to see your car in action. The American Autocross Series runs in the central valley (near Merced) and typically sets up courses that your car would like (as opposed to low grip small courses in the Bay Area). www.americanauto-x.com.

-Andy
AMRX7 is offline  

Thread Tools
Search this Thread
Quick Reply: Utlimate RX autocrosser


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: