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i am building my gtir for abit of time attack and grip racing next year. i will post pics as the build progresses. here are the specs of the build.
body and interior.
carbon hood
carbon fenders
undertray
rear diffuser
front carbon cannards and splitter
stripped interior with 8 point cusco d1 cage
carbon sparco buckets sparco 5 point harnesses
sparco wheel and shift knob
prosport boost, oil temp, oil pressure, egt and afr gauges.
cusco front and rear upper braces
cusco lower brace.
vehicle graphic wrap.
suspension and brakes.
wilwood 4 piston calipers with 11" rotors
rear cross driller and groved discs
ebc red stuff pads
bc coilover kit with 6kg/mm front and 5kg/mm rear springs
front poly bush kit
subframe lock kit
rear adjustable lower arms with heim joints
15x7 konig heliums with 205/50/15 falken 615's
engine and transmission.
cometic 1.0mm head gasket
BC 272 cams, sprindgs and titanium retainers
ported and gasket matched head
87mm cp pistons
arp rod bolts
rods stot peened
balanced rotating assembly
os giken twin plate clutch
arp head studs and main studs
autobahn88 exhaust manifold
gt3071 turbo
custom 3" bumper exit exhaust
xs power fmic
snow performance water/meth kit
z32 maf
mines ecu with custom map
greddy profec b spec 2 boost controller
koyo aluminum rad greddy cap
trans rebuild, gears cryo'd
front 1.5 way lsd.
should be a good circuit car..hope to get it down to under 1100kgs.
Tires - 205/50/15 falken azenis will be a joke for anything other than a stock DE powered sentra/NX on track, you will have these greasy in a matter of 2 laps with a built GTiR, let alone be competitive in any time attack. Your going to want to run a 225/45 shaved RA-1's at a MINIMUM or step up to 17's to take advantage of the wider tire selections. If you can run R-compound tires, then consider hoosiers or V710 tires. Prepare to roll/pull your fenders to fit.
Cage - find a builder and get a real cage built for your car, or consider an AutoPower cage if cash is tight... Cusco bars are for show.
Brakes - sell off any slotted/cross drilled rotors you have and run the cheapest blanks you can find. I'm also not sure about the EBC pads, but I'd recommend using a Wilwood track pad up front and invest in some ducting because those little 11" wilwood brakes aren't enough for what your talking about doing with this car.
Weight - I stripped my sentra down to the bare essentials and only got it to 2550lbs with a turbo and autopower cage... I doubt you going to be less than 2700lbs due to the AWD, maybe I'll be wrong, just pointing that out.
Suspension - Consider a custom Koni setup using the Koni 86XX inserts and GC hardware or equivalant. Having the ability to swap out spring rates(Eibach/Hyperco/etc) and ease of rebuilds on the koni's make it that much nicer to work with. Also, you'll be amazed at what a real dampener (koni) feels like to all the other stuff out there (sub $1500 JDM coilovers)
Motor - power isn't everything... even when it comes to time attack trials, the stock GTiR is a tough little motor. I'd suggest leaving the motor alone, invest in a good oil cooler setup, a quality FMIC setup, a large radiator, and do all the ducting you can to keep things cool. A good set of cams, open exhaust, and enough boost to keep detonation at bay is all you really need to start with.
edit - I see you have a water/meth injection kit, I'd maybe just use this to help keep detonation at bay and run alittle more timing.
You can take what you want from what I suggested... I've been playing with boosted SR20DE's for 5 years on track now and have learned a few things that I try to pass on whenever I can.
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Monty <--- Another victim of the go-fast crack pipe....
the car weighs 1220kgs or 2680 lbs stock so i see a 120kg reduction as quite easy to acheive. as far as the tires go in the super street class r compound tires are not allowed. depending on how the build goes and results next year i may move into the unlimited class where anything goes.
the car weighs 1220kgs or 2680 lbs stock so i see a 120kg reduction as quite easy to acheive
Have you actually weighed yours... I know this is the published weight that you can find with a simple search on the web. We have had a couple around our area that autocrossed with us, and with full interior/AC, the owner stated the car weighed over 3000lbs... but he could have been lying for all I know.
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as far as the tires go in the super street class r compound tires are not allowed. depending on how the build goes and results next year i may move into the unlimited class where anything goes.
What's the lowest treadwear rating do they specify for the street tires, I'd still recommend the shaved RA-1 or a Nitto NT-01 if all possible in a 225/45/15 size... their typically not specified as a R-compound tire, but could fall into the class because of the 100 treadwear rating.
McCoy, i see you said to ditch the drilled/slotted rotors and use the cheapest blanks.
is this because no matter what brakes u use they are going to wear out?
drilled rotors just crack alot faster and actually take away from what you want in the rotor, thermal mass. Nothing wrong with slotted rotors, but there not that important when it comes to track duty and only add cost to a wear item.
I go through a set of rotors a year, if I was putting down more power... I'm sure I'd be going through 2 sets of rotors per year. I have seen high HP subaru's go through a set of expensive rotors in 2 sessions because they didn't have enough brakes
The pads are where you don't want to cheap out on, and there will be some trial/error here. I'm a fan of the hawk blues for the Z32 caliper only because of the cost/performance factor. There are many things I don't like about them, but don't feel like spending X2 cost for the next track pad out there and these so far don't fade on the hottest of days and seem to last a while too. For the wilwoods, I had good luck with the polymatrix C pads, but havce heard the polymatrix B's are even nicer.
Look into whiteline.com.au for handling bits. Did you get your breaks to fit under your 15s? I think the cage you have should be fine as long as you weld it to you chassie. +1 for NT01 over 615. Lastly, a guy once told me that the way you will become fast is seat time.
i weighed my car at a local weigh bridge and with my fat ass in it my sub and amps and a half tank of gas it was 1387kgs..i weight about 100kgs or 220 lbs and the 1/2 tank i guess 30 liters is about 30kgs. i'm stripping it pretty bare, a/c , abs and heater boxes as well as stock seats all are very heavy..the brakes will not be a problem, i have done a couple of track days and they start to go off by the 4th or 5th hard lap but i dont brake much..it will pull down from 180kph consistantly without fade..as for tires i know the avensis arwe a bit bargain basement but i find they work really well and the lack of grip means less understeer if i flick it into corners on the power..it can easily be controlled in a slide..this is a preliminary spec sheet and some will no doubt change as time goes on. as far as the cusco cage goes i am looking for a bolt in and the cusco cage in my skyline i had i ireland saved me and my buddy during a slight off...about 200kph into a field.
i weighed my car at a local weigh bridge and with my fat ass in it my sub and amps and a half tank of gas it was 1387kgs..i weight about 100kgs or 220 lbs and the 1/2 tank i guess 30 liters is about 30kgs
good to know.
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i have done a couple of track days and they start to go off by the 4th or 5th hard lap but i dont brake much..it will pull down from 180kph consistantly without fade
As you get more seat time and get some stickier/wider tires on the car your going to find the brakes aren't going to work as well...
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..as for tires i know the avensis arwe a bit bargain basement but i find they work really well and the lack of grip means less understeer if i flick it into corners on the power..it can easily be controlled in a slide..
Yeah, but this isn't the fastest way through the turn
I weighed my RB when I got it. It was 1240kg (despite the quoted 1220 or 1190) It had aircon fitted ***. I got mine down to 1130 with replacing some and removing other bits. That was before f/g tailgate/lexan windows/kevlar doors etc go on.
You should quite easily get the car down to 1100kg and with some work well under.
Where are you gettting the under tray and diffusers from?
the diffuser is meant for a sti. i'm modiying the rear bumper to make it work.
Are you doing the diffuser for aerodynamics or looks? To really take advantage of a rear diffuser you really need a flat bottom (all the way from front to back) for this to work and the last time I looked that would take a lot of work to do on a GTiR. Throwing a diffuser from another car onto your car isn't going to make it anymore aerodynamic than it currently is.
I'm no expert, just been listening to those with more knowledge in aerodynamics and cars than myself and read some pretty good info on diffusers recently. I'd post it up, but currently the site is down .
It will help a little if it cuts down the air going into the rear bumper so it doesn't act as a parachute.
Well, that's not what a rear diffuser was designed for... and I can think of alot cheaper methods to help get the air past the bumper without the install of a decorative diffuser
No, it's not what it was designed for, but it's a by product of a decently designed one.
I realize that, but for alot less money you could probably build a flat panel of some sort to do the same thing, I'd assume both would require the same amount of work to fit under the car.
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You could just cut holes in the bumper, but that looks sh*te.
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