renkenkyo

iTrader: (6)

So my twins died at the track (road course) a few weeks back and I dropped off the car at the shop to go single. The car was mostly stock (touring model) except the few following things:

Widefoot sway bar mounts
Tein HA coilovers (10 kg/mm front 8 kg/mm rear)
Rotary Extreme Toe Links and Trailing arms
ACT clutch & light weight flywheel
Aluminium AST
Dual Oil R1 Oil coolers
Boost, Oil Temp, Water Temp, & Oil Pressure Gauge
Downpipe
Silcone Radiator Hoses
Necessary fluids (brake, tranny, etc.)
Removed the AWS

Going to add:
CompTurbo CT4-6065 w/ TBB .84 AR housing
Defined Autoworks V-mount kit
AEM series 2 ECU
AEM 3.5 bar MAP sensor, IAT sensor, AEM wideband, secondary temp in & EGT.
New wiring harness
6061 intake & hotside pipe
Greddy TI catback, SS mid pipe and downpipe (3")
Braille 4lb Lithium Ion battery


I figured since I'm going to have the car apart. I might as well do other things that might make the car more reliable on the track (e.g. eliminate the OMP). From experience can anyone tell me what mods would be good to do now and what ones to look to first as I start putting more into the car?

racingdriver

i would get a big nascar rad off ebay, get a big fluidyne or setrab oil cooler, 2 big bosch external fuel pumps, a fuel surge tank, a fuel cell with 2 pick up pumps, bigger 2nd injectors, fuel pr reg, , and change the .84 turbo housing for a .96-1.05.

I have roadraced my 93 rx7 since 1997. started with twin and went single in 2001.

Do not underestimate how much extra fuel you will need for a good single. With about 400rwhp you will probably run out of front brakes too. But Bigger calipers will sink the pedal down so you will need to upgrade to the 929 mc as well, and / or change the pedal ratio.

wouter

renkenkyo

iTrader: (6)

The V-mount kit comes with a Koyo N-flo; is that going to be sufficient?

I currently have a walbro 255 lph pump but I'm thinking of switching that out to the supra pump, is the bosch external fuel pump really necessary for ~360 rwhp? I'm looking for a very broad and smooth power band between 4000 to 8000 rpm so I think the .96 A/R will might be a little to much.

I'm also noticed that the steering isn't really responsive past 70 degrees (meaning that i don't get the same turning angle per steering angle); is this typical? I haven't really tuned the suspension as I'm not really sure how the settings will effect my cornering dynamics. The traqmate shows I'm pulling around .98 G sustained and I'm running Yokohama Advan AD08's (stock rims).

Brent Dalton

iTrader: (31)

Koyo N flo has been more than enough for me. Leaving the heater core behind the dash acts as a mini radiator as well and helps out some. The Remedy water pump will help as well, but I would get everything back operational and see if you have a temp issue before buying more parts. I suspect your temps will be fine. It's proven to help cars with twins out alot though.

I ran a walbro on my T78 track car without issue at around the same hp level. I ran 550 primaries and 1600cc secondaries at 13lbs of boost. Injector duty was always around 70%. Fritz runs something similar in his track car as well. The supra pump would prob. be a little better and a little more reliable than the walbro. Shoot Fritz a PM as I would guess he prob. has one he can sell you.

I would go also go with a twin scroll turbo with dual wastegates if you haven't pulled the trigger on anything yet.

I have the stock rack in my car converted to manual by Maval and it feels linear/proportional, but I will say that is something that I haven't paid that much attention to.

I'd get the car back up and running and back on track before you start doing other mods. The car will let you know what it needs. As racingdriver said, brakes will be on the short list.

One other thing I'd mention. The battery. I have played the tiny battery game and lost every time. If you are running an unlimited class, you may have to get your weight down as much as you can. If you are running something like NASA's TTS/ST2 or just doing DE's, do yourself a favor and get something like a Optima Red Top. It has a 3 year warranty and is available at every part store on every street corner in America. It's not any fun when the mini battery goes dead at an event and you have to jump it off all weekend or worse. The Optima goes dead, you drive to the nearest parts store and they give you a new one. Makes life so much easier. Not to mention, I don't have to put my float/trickle charger on the battery after each event now.

nofords

iTrader: (9)

If a 929 will fit maybe this will too.

I have that m/c on my FC booster and is a potential upgrade to the 929 M/C.

renkenkyo

iTrader: (6)

Lots of good info here. Seems like I should wait on getting the car back up and on the track before adding anything additional for cooling.

I haven't bought the turbo yet but what twin scroll turbo would you suggest? Is there a benefit for having dual wastegates as compared to a single larger one (thinking of running a 50mm turbosmart hypergate)? I can't put any major horsepower down due to limited aero so really don't want to go more than 360 rwhp but maybe I'm wrong (was already having to baby the throttle on some of the tighter courses).

Right now I'm running a optima yellow top and it works great, but with the v-mount I don't really have space unless I relocate it to the rear bins and that adds all the extra complexity and weight of wiring. The good thing about the Braille batteries is that they are Lithium Ion so it actually holds almost as much charge as the yellow top and keeps it for longer despite the smaller size.

Optima Yellow Top D51:
Cranking Amps @ 32F = 575 A
Capacity = 38 Ah
Weight = 26 lb
Size = 9.2" L X 5.0" W X 8.9" H

Braille ML9C:
Cranking Amps @ 32F = 434 A
Capacity = 36 Ah
Weight = 4 lb
Size = 5.8" L X 3.4" W X 4.25" H

So it's not only smaller but also 22 lbs less! Plus the power distributions is much better, where the cranking power and surge power avaliable don't really reduce as the batter gets to complete discharge where a normal acid battery does. See the below article.

http://www.braillebattery.com/index...._amp_hour_lah/

trainwreck517

iTrader: (1)

FYI, LiFePO4 chemistry (what Braille is using) batteries are very sensitive to temperature. Best operating temperatures are 20°C to 50°C.. with maximum allowed 0°C - 60°C (from top tier manufactures). As the temperature goes down, capacity significantly drops, and temperature goes up life significantly drops.

So if you want to use the Lithium battery, you will need to relocate it into the cabin. The engine compartment will be too hot for that battery type.

Also be aware, that vented gas from LiFePO4 battery is flammable so precaution needs to be taken same as with hydrogen venting from a lead acid. Even though the Braille is sealed, there will be a vent in case of over charge condition occurs to keep the batteries from exploding.

renkenkyo

iTrader: (6)

Ah, that makes a lot of sense. If you have to reroute it anyway then it's you might as well keep the standard optima.

Brent Dalton

iTrader: (31)

I would look into one of the small to mid GT35R or different manufacturer equivilant. Seems like precision and borg warner have some good models as well. The dual waste gates help keep the pulses from weakening each other in the rotary. It also help more precisely control flow through the wastegate. The main issue the rotary FD has in NASA race and Time Trial classes is they only measure horsepower to weight... not torque. In this regard, we are at a major disadvantage as the rotary will never have more torque than horsepower like alot of LS engines have. The intent is to maximize your hp/torque as best you can. It's probably better to do some research on it than take my word for it. I just know the basics of it(I put an LS1 in my car so I could have the best of both worlds.... best handling/suspension and brakes from the FD, and more torque with the same amount of horsepower).

As far as aero, It seems negligible at lower speeds. I'd say work on maximizing mechanical grip to "dig" more out of the low to mid speed turns as well as continuing to hone your driving skills before getting into aero too much. I think it'll make you a better driver in the long run. What tracks are you running on? Have you had a chance to compare your traqmate files with someone in a similar car on R compound tires or, even better, A6's?

renkenkyo

iTrader: (6)

Honestly I'm still a beginner compared to people we really go racing. I do about 1 track weekend a month around California. The tracks I run are Autoclub (California) Speedway, Willow Springs Raceway (International and Streets), Buttonwillow Raceway, and occasionally Laguna Seca or Infinneon Raceway. I want to go out and give Spring Mountain Raceway in Nevada a go but haven't had a chance yet. I went to a few track days a few years back and started putting in consistent track time this last year.

I've only compared my traqmate data with some of my friends who also run on the same days. It'd be great to see what other RX7's are doing on these tracks!

I'm not looking to do aero until I get the suspension sorted out and understand what I need to tweak in order to drive better. As far as power I'm looking for a flat and wide power band and as much torque as I can get out of the car. The turbo I'm getting is a 60/78 compressor and 74/65 turbine. It's somewhere between a T04E and a GT35R. I know twin scroll gives better response but I always thought you lost torque up high?

PandazRx-7

iTrader: (18)

Nice! Always cool to see for FD's around here at the track...I just started last year and I'm hooked. Which group did you go out with? I run with speedventures which has been awesome so far...

Regarding cooling set-up, I've found much success with V-mount and dual oil coolers on hot days both at Buttonwillow and Willow Springs...my water temps are usually between 87C to 92C pushing hard for 20 minutes. They key is good ducting.

Battery, I run a D51 Optima Yellow top and it has worked flawlessly for 3 years. I do kill battery via a 200amp breaker when stored.

Turbo set up, I run a twin scroll turbo with divided manifold but with one 44mm Tial wastgate, I had a boost creep issue with any WG spring over 13psi... ended up with a 10psi spring to run 13psi base and turn up with boost controller for anything higher. Turbo is the original 500R from Aspec with 1.06 A/R. Spools super quick... one of my dyno sheets around 16psi (rich) shows torque quickly climbing to 275lb by 4200rpm and steadily increasing to 325lb by 6200rpm then dropping off to 300lb by 7300rpm... not too bad.

Feel free to hit me up with PM if you need any advice/help with fuel, brake or anything else...

gracer7-rx7

iTrader: (16)

Try and get your hands on one of Hyperion's fuel surge tank covers.

renkenkyo

iTrader: (6)

Is to ensure you do become fuel staved?

I also run with speed ventures! I've been going out to Autoclub Speedway a bunch recently. I also run the D51 yellow top currently .

Hopefully I'll get my car up and running by January/February, don't want to get rusty. I'll probably take you up on that offer for advice!

I'm in the middle of trying to figure out which block off plates to run, getting the re-medy water pump, getting the v-mount from defined autoworks, and seeing how I can effectively eliminate the air pump and a/c.