25XP's X Prepared FC Rx7
 

I never got around to a "build thread" on my autox prepared Rx7, and it would have been a 21 year thread in the making. I have had my FC since 1990, and my attentions to it over the years have had life's destractions take me away from it from time to time. There were many small threads on TeamFC, but probably gone for good now, like my memory...
Thru the years, I never kept a good build sheet, or all my reciepts, and I was never one for technical geekness (no offence to those who are). I do tend to do my research at the time for a specific project, and find a way I can fit it into my skillset and budget. I have done all the work on my car except for the engine buildup and the Motec tuning. Learned it all from forums like this, and hands on, with a lot of just sitting there staring at the problem thrown in too.

So, I have started actually writting down my research in a build notebook, and I decided I would share my future projects along the way with you all.

For those who don't know, my car is an AutoX only car, that runs in X-Prepared. I have been autoxing for over 15 years, and I did okay on a regional level. Thus far the car is pretty well developed, but as aways, along the way there was not always time or money to do everything.

Recent projects:
Suspension:
I bought the AWR individual rear camber adjusters a year ago, and finally installed them. I have the center camber adjuster already, but I still had way too much negative camber. Even with 12" slick out back, they would light up way too easily. I am hoping to have zero negative camber when I align the car.
I also slotted the front strut towers to allow for more camber. The Hoosier 35A's don't need a lot of camber, but I was running into clearance issues and I was not able to get symetrical camber numbers. Free modification if needed.

Oil
As shown in the picture of Oil related goodies. When I installed my Mazdatrix oil pan baffle, I used only 1 gasket and gasket maker. It never seemed to seal perfectly, and I hate a leaky race car. So, 2 factory Mazda oil pan gaskets, Moroso stud kit, a FD factory oil pressure regulator, and Redline 50wt oil round out my oil projects. Oil related, but another to do project is redo the turbo dump line. Its AN fittings and SS line, and the short distance and angle was too sharp possilby and created an oil leak at the motor. More on that later.

I also decided to pony up some big bucks for an Ebay special short shifter. I couldn't pass it up, and I was dropping the tranny fluid and redoing the gasket anyway. Heck, I usually only shift once per run anyway, might as well be a short one. There is a great write up on this shifter already, so I will leave it out.

The bigger projects are the Jazz fuel cell, Bosch 044 pump, lines and Areomotive FPR install. I spent some time on the cell mount already (pics) and will update more when I run the lines and plumb everything.

I am happy that I can ditch the Nascar style rear spoiler that I was forced to run in BP, and now I can run a 2 plane wing. I am having the strut brackets designed at this time, and will post more on this as the parts come in.

The list continues, but thats it for now, on with the pics....
25XP

Dumb question: Why put the fuel cell up so high rather than buying/building one to hang low like the stock gas tank?

An overall description and pics would be good. You haven't mentioned a turbo, but I can't imagine you running in XP with a 044 and Motec without one.

From what I can see, your FC looks super clean.

Are you familiar with Steve O'belenes old S4 FC?

Not a dumb question at all, and I may rethink moving it below. The CG would be better below, so that would be a good reason to do so. When I initally thought about mounting the cell, I always envisioned above the rear deck.
Food for thought....
Thanks,
25XP

Which wheels and tire combos have you tried? Stock bodywork or something else? Thanks!

My turbo is a Garrett TE-460-1, .70 A/R Ptrim. HKS mainifold, Tial 38mm wastegate with a Turbonetics Godzilla blow off valve. Custom FMIC. 850/1000 injectors, Denso pump.
The car dyno'd just under 400hp in Denver, with a 50mm restrictor for the intake that I had to run in BP. The outside temp that day was 103, so maybe not the best pull. I removed the restrictor, and I am now in Norcal, so HP should be better, although I haven't dyno'd it yet.

Yes, I know Steve, I met him when I was at an event in CA, and I have spoke to him a few times on the phone when I was installing the Tri-Point wide body kit. Very nice guy, always happy to help.

Here are a few pics..
25XP

Subscribed! Clean looking car.

My wheels/tire combo are currently

Front 16x12 Real Racing wheels with 23x10.5x16 Hoosier 35A compound
Rears 16x12 Real Racing wheels with 25x12 Hoosier 35A coupound

They do make a 25A compound that tend to heat up faster, but wear quicker. I may try these in the future.

The real problem was I was simply getting too much negative camber in the rears with just the center camber adjuster. I had the camber adjuster maxed out with my ride height set for corner weighing. I should be seeing less negative camber with both the center rod, and the individual camber adjusters. Also a bit of body massaging to the tub where the suspension was most likely making contact during compression.

I know a lot of the FD autox cars run 18" wheels with Hoosier A6's and I have thought about that route when I buy new wheels. There seems to be some opinions on both sides as to what is better a DOT Hooiser or true slicks for prepared cars.

Also, to address the question, not stock body, TriPoint wide body kit.
Thanks,
25XP

Any idea how much wider the Tri-Point kit is compared to the AWR bodywork? I'm still struggling with a wheel/tire combo decision...

I don't have any exact specs on the difference, from the pics that I have seen, I would say the TriPoint is fairly bigger. What "fairly" is could probably be determined with a bit of reasearch. Tony at AWR may be able to answer questions as to what wheels were the AWR flares ment to fit.

From what it seems, the AWR kit is designed for the SCCA EP roadracing FC, so if you look up the rules to what the wides wheels allowed in that class are, I would suspect AWR made the flares to fit within those parameters.

The TriPoint was made for the SCCA AutoX FC in prepared rules back in the 90's. The "TriPoint" prepared car ran 16x12's. I have personally ran 16x12's with a "0" offset and they fit within the TriPoint wide body kit.

Hope it helps,
25XP

I've been trying to get Tony about this but he's strictly 15x7 23.5x9.5x15 EP slicks... he did refer me to another gentleman this morning, though, that I had a great chat with. He's got 15x10 with the Hoosier radial slicks, and more importantly, he's got 17x9.5 and 17x12 and says they fit inside the bodywork. He's going to get me backspacing numbers this evening. Thanks for your help! Appreciate it. And please keep us up to date with your car, it looks great!

FYI, You might consider contacting Joel ('frijolee' on this forum) from Ronin Speedworks since he has the Tri-point molds (improved) and sells the widebody kit now. He's very knowledgeable (as engineers can be) and can provide you with reliable data/info.

Those cheap fuel cells (I have one) will starve pretty easily. I have a 5 gallon one and it would starve with 2.5 gallons in it under cornering. Makes sense when you'll be generating between 1.25 and 1.5 G's. I had some internal baffling put in mine by a friend, but rewelding up that thin aluminum box was a nightmare, so I'd recommend trying to find a trapdoor type surge box that might fit through the filler opening.

I'm in San Jose and will be running in XP as well with my FD. Still got aways to go on being ready though. Should be out for early events next year.

-Andy

Well from what you say, that doesn't sound very good about starving the fuel cell.

Is your cell a 5 gallon Jazz cell? Does it have a sump? Foam? Where is your return line feeding into?

I was hoping to not have to do a swirl pot, but I may end up doing so if I run into fuel problems. I ordered all AN fittings and hardlines I think I will need for the installation of the cell, so a few hundreds bucks for another Bosch pump and swirl pot will be like a drop in the bucket!:crzyeye:

I hope we can meet up an event next season.
Thanks,
25XP

Remember this car from the other forum, Fantastic all around.

Any videos of the car competing ?

Good Stuff. Whenever I saw pics of your car I just always thought it was Steve O'Blenes' old car.

I have a Summit cell, but is basically same thing. Cheap foam on inside which doesn't do much other than shed little bits to clog your pre-pump filter, and a sump in the back that is great for drag racing. I ended up cutting of the top, putting in some walls around the sump with ball check valves, and running the return line over into that box.

Since welding was a total PITA the box I added didn't seal all that well, but it still works much better than as delivered. I'd be planning the external reservoir or finding some internal solution that fits through the filler hole. Problem with cutting these tanks is you need a pretty darn good Al welder to not have it warp like crazy when putting back together.

-Andy

^ you're switching to XP?? FFFFFFF (there goes my packwood NT tires :()

Thanks for the input and heads up on the cells issues. Would you recommend not running the foam these cells come with and save the pre filters potiential clogging?
Is there a better foam, or better not to run any at all?

I just got all my fittings filters and lines for the fuel system and will be mapping out the installation.

Thanks,
25XP

I ended up with no foam. While it helps with the slosh, it can't really stop the fuel from packing over to one side of the tank away from the sump. Part of my issues with the foam breaking off was due to putting the funnel to fill directly in the tank (no filler neck attachment). Every time you put the funnel or whatever in there and touch the foam, you can have little pieces come off. Over time enough can accumulate on the filter to be a problem.

Bottom line, these cheap cells were made for drag racing, not really road racing. A good cell with proper pickup will obviously cost alot more.

-Andy

Looking forward to reading more about the car. I love these threads. :)

FYI - Steve Kan is coming to town in mid Jan 2012 - see West section. So if interested in some tuning, get on it.

I am slowly talking myself into doing a swirl pot along with all the other fuel upgrades. I think I would regret not doing the fuel system the right way from the start. After Andy's replies about the cell, I figure I most likely will run into problems without it. I don't want to have to re-do the system or spend more time and money fixing a short cut.

So, time to read up on swirl pot set-ups.

I have seen some "homemade" swirl pots on this forum and others. Anyone with advice is welcome to chime in. If there are any members who are still fabbing them, please chime in too.


Update on what I have received thus far for the new system:
JAZZ cell with -8an fittings
1/2" aluminum hard line fuel lines for the feed side
10 micron -8an inlet/outlet fuel filter
Bosch 044 external pump
100 micron -8 inlet/outlet fuel filter
-8an to Y -6an splitter
Aeroquip SS -6an fuel line from Y to the fuel rails
-6an SS fuel line to Areomotive FPR
3/8" Aluminum fuel lines back to cell.
Assorted AN fittings to fit everything up.

I went with 1/2" hardl lines for the feed for ease as the fuel filters (Summit) had that size as well as the pump. It saved me a lot of downsizing reducers from the cell to the Y connector. All feed side fittings are -8an.

For a swirl pot, especially if one could be fabbed, I would like to stick with -8an inlet with -6an return to the cell.
I am thinking of running another Bosch 044 for the second fuel pump. Any issues with running that as the sump feeder pump?

Thoughts, ideas, suggestions, tips, tricks, rules, regulations or just good advice welcome.
Thanks,
25XP

I don't think you should need a second 044 pump; that thing is a monster. I moved mine from external to inside the fuel cell and added the in-cell surge tank... but that's for roadrace and you want a much smaller cell. In any case, I think two 044s would be complete overkill...

I need 2 pumps, one to feed the swirl pot and one to feed the rails.
I have read that some of the pre-made swirl pots need a low pressure pump to feed them.

Regardless, would need 2 pumps for a cell application.
Any suggestions on a swirl pot feed pump, if the Bosch is "too much"?
I have seen a lot of pics with dual Bosch 044, one for the swirl pot and one for rails.

Thanks,
25XP

Oh, I see how you're putting this together now, sorry, I hadn't thought it through correctly. Starting to feel like by the time you do a second pump and a swirl pot you'd be better off just getting a small fuel cell with a surge tank.

See above pics, and conversation between Andy and I.:nod:
Thanks
25XP

Great looking car, we still have not made the move over to non-dot slicks.

What are you using for dampers and have you done any roll center correction in the front?

Zack

I am using revalved Bilstein shocks with custom front strut inserts. Pretty smilar to the strut inserts that AWR sells. I have a friend who works for Bilstein help me out with them. I am using Hypercoil springs. ST front and rear bars and camber plates. Delrin bushings throughout. AWR rear camber indi and center camber adjusters.
I have Mazdatrix swaybar end links and one is bent, which does not give me much confidence with thier bumpstop elmininating rod end links. They look pretty cheap and I would like to find a better option. Aurora rod ends are high quality and there enough tapered bolt and spacer kits that would look like they would hold up well. The hard to find off the shelf is the adjustable coupler nut that would fit the FC's thread on the PS rack. While it a left hand thread could be made on a lathe, I have not been able to find an off the shelf coupler in the correct thread size. This is another project I want to handle over the next couple months before next season. The car is low enough that bumpsteer needs to be corrected.

Anyone with a lathe want to make some coupler nuts?? From what I did as some quick research, a high quality bump steer kit could be made under $165.00 give or take. This would be using Aurora's alloy steel metric rod ends. Thoughts, ideas, suggestions?

25XP

Yeah we have been working on a set of lower ball joints for the front as well to do roll center correction. I should have the model done pretty soon....if I get a break around the shop haha.

We have been through three suspensions on the car I codrive sometimes, went from teins to koni doubles, and finally settled on a custom bilstein setup as well. The car has never put power down better than with the custom valved bilsteins out back.

I agree that front roll and bump center correction should be figured out on the car, hopefully more people will become aware of the effect it has on handling and start figuring this stuff out!

Zack

So I spend some time completing a few things on my list.

After several hours under the car, I finally installed my Moroso Oil Pan Stud kit. Its a great mod to do, but NOT while the motor is installed in the car. It took forever and after removing the front swaybar, and PS rack, as well as some creative thinking with tools, its all snugged up tight. Don't get me wrong, this is a great setup if your using an oil baffle with 2 gaskets. It just is very tricky to install with the motor in place. I hope it keeps my oil inside the motor and not seeping out.

Also installed my Miata short shifter. I have been wanting a short shifter forever, but couldn't justify $150 for one, esp since autox usually only warrants one shift. After a few mods to the Miata kit, I have a nice firm and short shift now. Money well spend. I didn't take pics of the install of either of these as they are boring and you can get step by step pics at Regan rotary racing.

I thought I had all of the fittings I needed for my fuel system. A slight mishap with Pegasus and I am delayed a few days. Their excellent customer service is taking care of the problem. I should have what I need in a few days.

So I started laying out the parts for my fuel system for reference. Here is what I have.
From the Jazz 5 gallon fuel cell -8an outlet to a 1/2" hard line to the -8an of the Holley Blue inlet to the -6an outlet. 3/8" hard line carries it to the -6an inlet on the swirl pot. Pressurized fuel exits via -8an outlet to the -8an inlet of the 100micron fuel filter, exits vial -8an outlet, 1/2" hard line to -8an inlet on the Bosch 044 fuel pump. Exits via -8an to 1/2" hard line to -8an inlet of 10 micron fuel filter. Exits via -8an to 1/2" hard line to -8an bulkhead toward the engine bay.
Return lines enter from FPR to -6an bulkhead to 3/8" hard line to -6an inlet on swirl pot. Over flow fuel exits swirl pot via -8an outet to 1/2" line to -8an inlet on fuel cell. Remaining top -8an fitting on fuel cell will be vent.

While I was a bit skeptical about the CXracing swirlpot, I couldn't pass it up for the price I looked at an ATL unit, but it was 3x the price. There were a few units from over the pond, but they were 2x the price. I checked all the fittings first thing, as another memeber had issues. There was a bit of buffing rouge on the fitting, but easily was removed and the fittings went on just fine.

I used some tape to simply get an idea of where the lines would go. The Holley pump flows in the wrong direction for the swirl pot to be on the passenger side as I wanted. I may rethink a mounting solution to it.

Any thoughts, ideas, suggestion, red flag alerts or comments, please let me know. Also those who have bent/flared a lot of hard line that have any tips, chime in.
Thanks,
25XP

pic

pics

i dont feel like digging through the rules right now, but isnt there something about requiring a firewall between fuel system and driver? i've considered a cell+swirlpot, but firewalling it seemed like a huge PITA considering the hatch layout

Yes your right, I will fabricate a fire wall between the fuel system and driver.
25XP

I received the rear wing and assembled it. The dual wings are ARP 55" silver carbon fiber and the end plates are aluminum. The struts were custom made by Ciro Design Racing. The wing conforms to the XP rules for total surface area, total height and contained within the bodywork. That is why the struts are "forward struts".

I am happy loose the Nascar style single plain spoiler. It did a okay job, but also was pretty heavy. I haven't weighed them both yet, but the new one is a tad heavier, however the downforce will be worth the weight.

In the pics, it is simply sitting on the car, I will take some more pics of the mounting brackets and finished results.

Overall I am happy with how it looks, the struts are nicely machined. I will probably look to CF end plates in time to loose some more weight.

I have put the car on a even further diet. I have already removed so much, now comes the more expensive weight saving changes. More on that to come.

how much do you weigh at the moment? whats your target?

I am not quite sure how much the car weighs at this time. I have had some fluxuation in the weights that I had previously. The SCCA offical scales seemed a bit heavier then when I weighed it last.
On private scales the car was around 2100lbs, but I have made some changes to the car since then. Somethings added weight, other removed it.

I am trying to do those last little things that probably won't add up to more than 25-30 lbs. The car has almost eveything removed that could be removed, now its the last 5% of weight.
Removing the stock gas tank was one of the bigger weights I wanted to remove. I am also redoing the aluminum dash that I had. This weighed just a few pounds, but the new one will be even lighter/smaller.

I will remove what weight I can, get the car weighted again. I would like to get close to the min weight for the Rx7 for XP. I don't think I will be underweight and have to add weight, but if by chance I am under, I will add it to help with corner weights.
I would like to work toward less rotating weight in the future.

25XP

Nice car.

Can you tell me more about your bilstein setup? Mainly the rear. Are they just standard FC bilsteins or custom?

The Bilsteins were reworked by my buddy who is a shock developer/engineer for Bilstein. He worked on them about 5+ years ago. I think they were simply revalved, but I don't recall the exact specs. I left it up to his knowledge as he is also an autox'er.

I just ordered Super Now bump steer kit for bumpsteer correction.. I figured I would give them a try as they looked a bit better then the Mazdatrix units.

Any idea what time frame Tony is going to have the kit ready?
Thanks,
25XP

No, but send him an email, if more people are interested he'll probably work a bit harder on getting it done.

tony "at" awrracing.com

I'm building my own roll center kit this winter, i'll make a thread about it when i'm done. should be able to move the ball joint down anywhere from 0-2.5". ish.

one like the VW pieces would work fine:
http://i27.photobucket.com/albums/c1...T/SNV31203.jpg

I'm not sure if their stud is the same diameter as ours though.

After welding up the bracket that mounted the fuel cell and laying out all the pumps and filters, I took another direction with the mount.

I was reluctant to cut up the rear hatch for really no reason, I mean I cut up a percfect turbo hood, sliced my rear quarters for the wide body kit. So after some "getting over it" I went at it.

I wanted to get the cell as low as possible without runnning into plumbing issues, and also keeping it all above 6" from the ground. I also wanted to keep as much of the pumps and filters inside the car, while keeping the anount of bulkhead to a minimum. This meant stuffing as much as I could into the spare tire well. No easy feat and an exercise in patience. Some of the pumps/filters just simply couldn't make it, and will end up being installed under the car.

I had never worked with aluminum hard fuel lines, and after a bit of "practice" I was able to get the hang of it. The hard tube bender I bought was great at kinking the 1/2" tube so I relied on the flexible slip bender. This worked like a charm.

Here are a few pics of the process, lots of time in little adjustments to make it fit correctly. Still lots of work to go. Hard lines have some benifits, but certainly take more time to create.

Thanks,
25XP

I read on a forum that VW studs are 17mm studs and just put a caliper to a new set of S4 balljoints I have lying around and they're 18mm studs so no go on the VW RCAs.

Sorry 25XP, I'm finished side tracking your thread... I'll let you know if I hear anything from AWR.

http://www.youtube.com/watch?v=lyA8G...c4AUAAAAAAAAAA

A video I found a couple seasons ago.
Tires temps and ambient temps were pretty low that day. I had problem putting down power without breaking the rear loose.

I set my camera up to watch the gauges more then where I was going, so that is why the angle is like this. My camera isn't that great so it didn't get the gauges like I wanted. Oh well, better than nothing.

This is my old dash layout, the new one will be minimal in comparison.

25XP

Gee, I didn't realize how much of a shifter jiggler I was in that video!

So I have finished pulling all of the suspension off the car. It had been a few seasons since I did so, and I wanted to inspect everything.
I decided to POR15 the suspension parts while I had them off the car. The stuff works pretty well, and should hole up well. I will post some pics of the suspension just before I put it back together.

I bought some new rotors for the car, the OEM issues were still on the car. They held up very well, a lapping day at Lime Rock, several Time trials, 80K of road use as well as many autox's. The problem was I could not get the frot hubs out of the rotor. Not too surprising, aluminum hub with steel rotor. After breaking my 3 pound sledge, I decided I would just take them to a press.

Enter the local VW mechanic. I am new to the area, don't know them but thought I would give the locals a shot. They have been there for 25 years, so they must know what they are doing.......

I give the veteran mechanic the rotor and 10 min later he comes back with 2/3 of my rotor. No problem, I have new ones. But he can't grasp the concept that the hub has actually moved. I had to draw it out for him in crayon. Then he just couldn't see why it would be so hard, he didn't believe me that the hub came out. He looked at me like I had 2 heads when I told him alumium and steel some times bond together with heat. He got one out today, but he wanted to soak the other one in some special penatrating oil before he did the second one. Lets just hope he doesn't mess the hub up.
Time will tell..

25XP

throw it in the freezer and it'll probably come apart

A little bling for under the hood!

Things are coming apart to get things complete with the fuel system. I removed the manifolds to give them some shielding treatment before I run the new fuel lines.
I think this DEI Gold foil tape is pretty cool stuff. Combined with my new DEI Ti turbo blanket, I hope to keep things a bit cooler near the turbo.

25XP

i like the block off plate!