Jump to content
SAU Community

Recommended Posts

I recently added some more power to my R35, whilst it was great for simple straight line stuff (running 11.1 @ 125mph at WSID) i found that my circuit laps times have actually gone backwards (!).

My conclusion: the extra power is inducing VDC/Traction Control "events" (wheel slip) and pulling power.

Background: If you've ever forgotten to put your R35 in 'R' mode on the circuit, you will have noticed/heard/felt the system working each corner of the car, with the threshold of slip being rather pessimistic. However put the car into 'R' mode - the system then allows a higher degree of slip & yaw, less instrusive & better laps times, and more fun...

Anyway, with the aftermarket tune - say +60rwkw - 'R' mode seems like 'non-R' mode used to! (on the circuit anyway). I think the extra power is overwhelming the delicately tuned 'R' mode thresholds built into the VDC calibration.

So... consider this a heads up! Adding gobbs of power isnt going to immediately translate into quicker lap times. Unless you're comfortable turning VDC off, and driving the thing on your wits alone.

The sprint series i am in doesnt allow aftermmarket tunes, so i need to remove the tune anyway (for this coming weekend) but i thought this might spark some debate on the matter. Perhaps some others have tried adding significsant power to the R35, very interested in your thoughts (in a circuit racing context).

Edited by LSX-438
Link to comment
https://www.sau.com.au/forums/topic/286808-r35-circuit-work-and-more-power/
Share on other sites

Driver tuition is your answer to better lap times, not more power!

Driver training is probably never a bad thing, especially for amateurs like myself. But i dont think that's the primary issue here. It sure is easy/tempting to suggest that though; most people that have not driven the R35 on the track think it drives itself. That's probably true to an extent... up to about 80% of the cars potential.

That extra 10 to 20% isnt a cake walk.

Anyway, with normal power, in R mode, on the track, with RE55's, i don't feel VDC kick in, ever - unless i've made a huge error. However with (significantly) more power, it seems to break loose much more easily. Extra slip isnt necessary a bad thing, in fact i reckon a certain percetage of slip is required for the absolute quickest times (dependig on tyres). However the VDC calibration only allows so much slip. No amount of tuition is going to get around this - it's a hardware/calibration issue.

The answer is, be content with standard power OR be prepared to turn VDC (and your warranty) OFF. It's probably a non-issue, given anyone running a tune probably doesnt have a warranty anyway. This is just a heads up/fyi for R35 owners, and what to expect when you add gobbs of power :)

Edited by LSX-438

I actually noticed the increase intervantion of the stability control even with just the Midpipe added. In R mode I am getting it come in more than I did before.

I have not tracked since the mid pipe was installed however I have a day planned in about 3 weeks so I can finish of the Bridgestones before the Dunlops go on.

It is an interesting point you have raised Duncan and I am curious now.

Cheers

This is a fairly common trait in newer vehicles equiped with stability control (and importantly torque limiting protocols). Adding more power often leads to excessive interuptions, whether it be a tow vehicle or race car, and could possibly lead to a slower lap.

My suggestion would be to switch it all off.

This is a fairly common trait in newer vehicles equiped with stability control (and importantly torque limiting protocols). Adding more power often leads to excessive interuptions, whether it be a tow vehicle or race car, and could possibly lead to a slower lap.

My suggestion would be to switch it all off.

You can end up very very sideways with it switched off

Believe me I know

90 degrees to the track at Winton in the sweeper

lol, come on Jeff, you can end up sideways in anything if you fluff it up mate :woot:

We did last year's Tassie Tarmac Challenge (Rally Burnie) with it all off in some real grotty conditions and only took it off road twice ;)

Edited by Marlin

This leads me to a question i should know the answer for... when you turn VDC off, what exactly is turned off? Is it just the traction control mechnaism? What about torque split (front vs rear) and god know's whatever else is in the system?

yeah turning it off is the only answer. even in R mode with more power you will be cutting in the traction control/stability control often and it will slow your times.

I have driven standard R35 on track and upgraded (exhaust, ecu etc) and prefer VDC to OFF. yes you will find yourself dealing with some power oversteer but its very controlable if you know how to use throttle and opposite lock (and I'm sure you do mate).

it's not like it becomes a scary unbalanced car when you turn VDC off. the chassis is great, it still has loads of grip and the active torque split is still working as it should. just no traction control will cut in no matter how sideways you get it. but I honestly reckon you would have to actually try to spin one off the track. they are very controlable in a slide and you can easily balance the car on the throttle. and it's fun. :woot:

Its one thing to sit here and tell you how to drive....but from what I know you already have more than a good handle on that.

The answer lays in something else, and thats the ability of the turbocharger system of the GTR to unbalance the car. If you stand on the throttle at the wrong point of the corner in a GTR its easy to unbalance the car, even slightly step the tail out, and lose time. VDC-R isnt so much the problem, but the ability of the car to change direction and correct for a rapid shift in lateral G-Force really is! The key is to be as smooth and progressive as possible, with the fastest lap times coming to the calmest driver :banana:

This is why when I custom tune a GTR for the track I do this -

customtune.jpg

Notice that the boost curve progressively pulls away from stock and then only by a psi or so from 4200 (thats over an off the shelf Stage II Cobb tune). The key to giving a GTR more power AND improving lap times is by minimising the throttle-on imbalance of the car and keeping the power curve as linear and 'spike free' as possible. This is difficult with an airflow based wastegate duty cycle table (as the GTR has from the factory), so we spend many hours developing wastegate control maps that keep boost spikes out of full throttle upshift and keep the GTR balanced on the exit and transition :(

This is not saying the way anyone else does it is wrong. There are some out there in Aus that seem to have a good handle on the GTR and reflashing. Just this way is how we do it after spending a few hundred laps trying different things in our own R35 :)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...