Built R33 GTS-T, soon to become a Nürburgring track car

[skylinecouple]

Totally agree with finding a tuner and asking him (her ?) what engine management system they are happy with. Personally, I'd prefer to get a stand alone system I can play with for track days in case of temperature changes, fuel changes, load, speed & just because. I have a Power FC due to ease of use and because I just can't stop tuning  and playing with different fuels, exhaust & turbos. It's fun. Beats listening to music.

Yes, that is a small turbo and will most likely cause problems at wide open throttle on the longer sections. So many things to check for best thrills. Exhaust size from turbo to tail pipe including cat. If it isn't heating up it probably flows well enough but 3" all the way through as a minimum. Injectors need to be 700cc as a compromise for tuning ease or 1000cc if using E85 or similar fuel. 

Tires & brakes are far more important than power which is why I would like to see a free revving engine (exhaust) and enough fuel for the long straights (injectors/tuning). Check your fuel pump, it's probably 25 years old as is your fuel lines. Get some good coil-overs with 8kg front/6kg rear as a starting point. Then Tires, got to be worth 5 seconds a lap just with tires at the Ring.

And for a huge leap in predictable handling get rid of every rubber bush in the suspension. Solid mount or urethane the differential and while your there get a 1.5 way.

Learn to do things yourself rather than a shop or this may be an extremely expensive experience. 

[Alex787B]

Thanks for this detailed answer mate. You seem to be well informed about upgrading a Skyline so I've got a few questions for you, if you don't mind.

- My goal would be to reach 400 bhp. I believe this is a nice figure to have something effective on the Nürburgring without having an overkill machine. Also trying not to exceed 1.2 bar to avoid replacing head gasket... Which turbo would you recommend to reach this figure ?

- I wish to stick with Unleaded 98. I believe 700cc injectors will suit that setup without any problem (isn't that too much for only 400 bhp) ?

- the biggest interrogation mark is : when will the cat become a blocking point ? Of course it struggles to warm up as I said before, so as you pointed out that means there might be a little margin there, but I hardly believe the car can be tuned up to 350/400 bhp with an OEM cat on... even with a fine mapping. I would like to keep the cat as it makes the car 100% road legal... I'm insured for Nürburgring Touristenfahrten and would like to avoid removing the cat for that reason - that would be sufficient for the insurance to discard themselves should a drama happen.

Also you are right on that too - good tires and coilovers just changed the car. Switched from cheap Nexen tires + HSD coilovers to NS-2R semi slicks + TEIN flex coilovers... Was a great investment, just need to be careful if I drive the Skyline under the rain lol

For all these upcoming upgrade, I'll be able to install parts myself (except the tuning/mapping part) as I've already done most of these things in the past, on other cars.

Edited September 16, 2019 by Alex787B

[skylinecouple]

If you hold the cat to the light and you can't see through it at all but can barely see some light then the cat is possibly a 300 cell. It sounds like you won't be able to use a 100 cell cat which is best for free flow. European laws I know are very strict but there are ways. For instance, try a 200 cell cat and this should flow enough for the power you are after. The size of the body is crucial so go with a 5" or a minimum 4" cat body. Don't worry, it will still heat up especially after you full throttle it once or twice. After that it should maintain the heat and therefore the efficiency. 

400hp would be a good start for the ring. Skylines have short gearing for tracks like that so maybe look at what differential gears others have tried especially if you go over 400hp. Maybe a 3.7 would be better. And hey, glad to see the tire change. Good choice.

Yes, 700cc injectors are a good choice. Easy enough to tune. As for turbo choice, that's where it starts to get hard. Even the slow corners there are pretty fast so again, I would get something a little bigger. For a low stress engine and to reach the 400hp try the proven GT3076 internal wastegate. Use the .82 hot side. T3 of course. Yes, the dump pipe will have to be fabricated. However, why not have a look at HyperGear Turbochargers. Something to bolt on without any mods to the dump.

If mods don't bother you go Gt3076, keep boost at 18lbs, add cams. 3.5inch dump and 3" exhaust. This should keep the engine from over revving, free up the exhaust flow and an overall good track package.

Check every ball joint, nut, bolt and clip. These cars are old. Replace wheel bearings if any doubt about their age. I was at the Ring years ago and would like to take my car there but never going to happen. Work, work, work. But to be flat out on one of the fastest straights in the world, wow, what an experience.