Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Race Car Tech
Reload this Page >

More clarification on my Ultimate Autox-er build...

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

More clarification on my Ultimate Autox-er build...

Old 08-02-05, 10:29 AM
  #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
More clarification on my Ultimate Autox-er build...

O.K, as time goes on, I get more info on this project, and I start to flesh it out in my head.

Starting with a GSL-SE, 10k, and 4 days build time:

2nd gen turbo front clip: Nets me aluminuim control arms, better brakes, more options for wheels, a turbo motor.

Smaller turbo on the motor (for faster spool/flatter torque curve)

Light flywheel

4.30 rear end (to keep a little load on the motor)

Possibly keep -SE gearbox (for lower gearing vs. 2nd gen)

g-force tri-link rear end, or possibly miata swap...

Tire the crap out of it, and spring the crap out of it.

Thoughts/modifications/criticisms?
Feds is offline  
Old 08-02-05, 10:48 AM
  #2  
Former Rx7 *****
10 Year Member
 
Cheers!'s Avatar
 
Join Date: Nov 2001
Location: Mississauga
Posts: 4,532
Likes: 0
Received 0 Likes on 0 Posts
this ultimate autox'r what class will it be competing in? No point building a ultra custom car when you are outclassed. Might as well get some ex FSAE cars from the states. Several schools are trying to sell their old ones.

FSAE cars are built for around 15k USD. That is how much the 04 Queen's FSAE car costs us if we had to purchase every single part with the machining time factored in.
Cheers! is offline  
Old 08-02-05, 02:25 PM
  #3  
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
The class is me vs. another RX-7 with the same constraints. I just want to do it better.
Feds is offline  
Old 08-02-05, 03:45 PM
  #4  
GET OFF MY LAWN
10 Year Member
iTrader: (1)
 
jgrewe's Avatar
 
Join Date: Feb 2005
Location: Fla.
Posts: 2,838
Likes: 0
Received 0 Likes on 0 Posts
Maybe a 4.87 rear gear, easier to downshift to 2nd at speed for a slow turn. It would all depend on the courses you normally get. Other than that, it all looks like a nice combo. Practice left foot breaking to keep that turbo spooled up!
jgrewe is offline  
Old 08-03-05, 09:48 PM
  #5  
Hobby or mental illness?
10 Year Member
 
RoadRaceJosh's Avatar
 
Join Date: Sep 2004
Location: SW Washington
Posts: 478
Likes: 0
Received 0 Likes on 0 Posts
Do you mean to graft the entire 2nd gen front clip to the GSL-SE? How does that help with wheels? Don't you have plenty of 4x100mm wheels available? How do you plan on doing this in 4 days? The turbo gearbox is quite a bit stronger and you'll want that strength if you turn up the boost. Why are you starting with an FB anyway? I'm confused!
RoadRaceJosh is offline  
Old 08-03-05, 10:13 PM
  #6  
GET OFF MY LAWN
10 Year Member
iTrader: (1)
 
jgrewe's Avatar
 
Join Date: Feb 2005
Location: Fla.
Posts: 2,838
Likes: 0
Received 0 Likes on 0 Posts
I think he's just going to mount the x-member from the FC under the FB. That will give him all the moving parts of the suspension.
jgrewe is offline  
Old 08-04-05, 12:33 AM
  #7  
Hobby or mental illness?
10 Year Member
 
RoadRaceJosh's Avatar
 
Join Date: Sep 2004
Location: SW Washington
Posts: 478
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by jgrewe
I think he's just going to mount the x-member from the FC under the FB. That will give him all the moving parts of the suspension.
Really? Are there any other threads on doing this? I have a GSL-SE and wouldn't mind ditching the recirculating ball steering.
RoadRaceJosh is offline  
Old 08-04-05, 09:56 PM
  #8  
Plastic Jedi
5 Year Member
 
JEC-31's Avatar
 
Join Date: Sep 2002
Location: Kentwood, Michigan
Posts: 583
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Feds
..., and 4 days build time:


Thoughts/modifications/criticisms?


My thought is that there's absolutely no way you'll succesfully complete a project of that scale in 4 days, even juicing up and going 24 hours per.

1) The amount of fabrication and design required to make major suspension swaps work takes time to sort out.
2) Playing around with custom turbo setups means lots of careful tuning, not plug-n-play.
3) I seem to recall that the13B-T motor doesn't exactly drop right in to a RHD FB, there's a steering rack where the turbo belongs. There's an Australian write-up on how to get around it somewhere on this Internet thingy but I can't find it.
4) "Tire and spring the crap out of it" takes tuning too, or you wind up with a stiff ride lacking useable grip under auto-x conditions. And if you have the suspension swap you'll be forging ahead into new territory.

I think a realistic time budget assuming no job and no significant other is 4 weeks. If you have an actual life then we're looking at months if not a year plus, man.


OK I'm done being Mr. Negative-*** Devil's Advocate. All I'm sayin' is don't rush it, it's an awesome Ultimate Trackday Car concept, and one I've nearly committed to myself (this was before my avatar LOL). Take your time and do it right, and it'll be one hell of an RX-7!
JEC-31 is offline  
Old 08-05-05, 08:04 AM
  #9  
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
O.K. Pretend like this is monster garage. Pretend I have 3 other guys, unlimited tools, and all the hoists/etc. I can get y hands on.

If this plan is NFG, what do you suggest? Any other ideas?
Feds is offline  
Old 08-06-05, 10:43 AM
  #10  
Plastic Jedi
5 Year Member
 
JEC-31's Avatar
 
Join Date: Sep 2002
Location: Kentwood, Michigan
Posts: 583
Likes: 0
Received 0 Likes on 0 Posts
OK I'll play along with Fantasy Rotary project.

The plan is good, starting with the GSL-SE is correct.

Which path you choose for underpinnings must be cohesive. Don't mix the FC front suspension with FB rear tri-link setup, it'll be odd to have different bolt patterns on each end.

Option 1: keep FB hubs and solid axle with CP Racing (or build yor own VW-based rack-n-pinion steering rack) steering up front and G-force full-race tri-link out back.

Option 2: Strip unibody of all FB components and weld in complete FC front and rear suspensions. This will require obviously major cutting and fabbing of sheetmetal, you may even have to weld in chunks of the FC unibody that contain the mounting points. The striking advantages to this are: One donor car, end up with same bolt pattern all around, as well as same track width front-rear, and lots of trick parts available for tuning FC suspension.

Option 3: Fab in the FC hubs up front and weld in a Miata rear. Many of the same difficulties as #2. What's the bolt pattern of Miatas anyway?

Don't forget to make an appointment with the Magic Horsepower Fairy to come visit you as well.
JEC-31 is offline  
Old 08-06-05, 11:25 AM
  #11  
Senior Member
10 Year Member
 
Join Date: Nov 2003
Location: Victoria, BC, Canada
Posts: 468
Likes: 0
Received 0 Likes on 0 Posts
Option 3: Use a GX front suframe to have 4x114.3 on all three corners. Do the rear as per usual. With this suframe you pretty much have to go with a FC engine, may I suggest standalone and PPort? Or with standalone go high-comp/low-boost.
www.bcrx7.com/swap.pdf

Grant
grantmac is offline  
Old 08-06-05, 01:10 PM
  #12  
Speed Thrills
10 Year Member
 
Brent_F's Avatar
 
Join Date: Aug 2003
Location: TN
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by jgrewe
Maybe a 4.87 rear gear, easier to downshift to 2nd at speed for a slow turn. It would all depend on the courses you normally get. Other than that, it all looks like a nice combo. Practice left foot breaking to keep that turbo spooled up!
The gearing is extremely important in auto-x. The stock SE set-up (tranny and 4.10 rear end) I use is not bad where I run. I frequently wish the gearing (esp second gear) was longer as in a second gen tranny. I recently ran a friends car equiped with a second gen tranny in an SE and mild port job 160ish hp. This combination worked quite well in what was the fastest auto-x I've ever experienced (65+ mph).

My point is think realistically about your power and your course before choosing a final drive set-up. remember you can vary your tire diameter to change final drive also. Do some calculations and try to observe some similar set-ups and where they do and don't work. your gonna put alot of time and money into this from the sound of it. So do your homework and make sure its something worth having when your finished.
Brent_F is offline  
Old 08-08-05, 09:58 AM
  #13  
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
Cool, useful information... Thanks guys.

The 4-bolt 2nd gen is a good idea. Matching bolt patters are nice. I had thought about the Miata rear end, though complexity and bolt patterns took me off again.

I wonder if I should set up 2 trans (-se and 2nd gen) and maybe 2 rear ends (different gear sets) for day-of-comp-swapping....

Keep 'em coming, this is great stuff!
Feds is offline  
Old 08-10-05, 08:35 AM
  #14  
Rotary Enthusiast
10 Year Member
 
Join Date: Oct 2002
Location: Fairfax, VA
Posts: 1,415
Likes: 0
Received 0 Likes on 0 Posts
Screw it... no rules? V8 swap.

Dan
Lt. Dan is offline  
Old 08-10-05, 04:55 PM
  #15  
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
Yeah, I'd love to do a V-8 swap, but I will have to clear it with the other members of my team. A V-8/Auto combination would rule old skool!
Feds is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Turblown
Vendor Classifieds
9
03-30-19 10:17 PM
jdayau
Build Threads
6
01-22-16 08:13 PM
jim_chung
1st Gen General Discussion
10
10-04-15 09:09 AM
josef 91 vert
2nd Generation Specific (1986-1992)
14
09-17-15 09:22 PM


Thread Tools
Search this Thread
Quick Reply: More clarification on my Ultimate Autox-er build...


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: