Some very helpful info I stumped upon

**cschepp** · 11-10-2011, 05:52 PM

So even though I am not going to be staying in the skyline scene for much longer I would still love to share with you some info for those who are:

http://www.gtrusablog.com/2010/05/re...2-r33.html?m=1

This link actually was very informative and helped out with some basic problems you could run into and also some things you could prevent from happening. I hope this helps

**gtrjon** · 11-10-2011, 05:57 PM

nice post. one of the best single links i have seen so far. sums up about 90% of the posts on here

**cschepp** · 11-10-2011, 07:27 PM

Ya I hope this is alot of use to many people here because these questions are asked quite frequently.

**MKIV** · 11-10-2011, 07:36 PM

STICKY? Amazing find for the GTR guys. Well done Op. if I'm lucky maybe the author will type up an article for the GTS models as well.

**bellis_GTR** · 11-10-2011, 07:51 PM

Very nice info there Chris. Good detail to why you should and shouldn't do things. I booked marked it! It's good to have this info even if you know most of it. You never know.

Although I had one question. They talked about #6 cylinder leaning out. I heard tuners can give you a safe to richen it up a bit more. Im not sure what they do. Can anyone explain that to me please. I want to make sure to tell my tuner about that in case he doesn't know him self.

**Skym** · 11-10-2011, 08:20 PM

If using stock ECU, richen it up, as don't have individual cylinder fuel trim (I think requires wideband on each runner or just run it tad richer on those cylinders). If using Link, ViPEC, Motec ECU, they have individual cylinder fuel trim feature. Also I think with PowerFC you can adjust fueling on each cylinder.

If intake plenum is designed correctly (JUN, Hypertune?, etc), don't have to worry too much about it leaning out on 6th. It's due to angle of entry to intake manifold that sends all the air to back of plenum and shape of intake plenum plays a role.

This is the correct way to design a front mounted intake plenum (similar to JUN, etc) and includes flow data -

http://forums.hybridz.org/index.php?showtopic=68639

As you can see where the throttle body is aimed, those cylinders get more air. Then look at stock GTR plenum and it's obvious why 6th gets more air.

**PurpleStreak** · 11-10-2011, 08:45 PM

Hmm, that explains my low compression on #5 & #6 :-)

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**bellis_GTR** · 11-10-2011, 09:23 PM

Originally Posted by Skym

If using stock ECU, richen it up, as don't have individual cylinder fuel trim (I think requires wideband on each runner or just run it tad richer on those cylinders). If using Link, ViPEC, Motec, ECU, they have individual cylinder fuel trim feature. Also I think with PowerFC you can adjust fueling on each cylinder.

If intake plenum is designed correctly (JUN, Hypertune?, etc), don't have to worry too much about it leaning out on 6th. It's due to angle of entry to intake manifold that sends all the air to back of plenum and shape of intake plenum plays a role.

This is the correct way to design a front mounted intake plenum (similar to JUN, etc) and includes flow data -

http://forums.hybridz.org/index.php?showtopic=68639

As you can see where the throttle body is aimed, those cylinders get more air. Then look at stock GTR plenum and it's obvious why 6th gets more air.

Thanks for clearing that up. I have a stock ecu atm and will probably be using Nistune since that's the cheaper way. Id love to get one of those higher class ecu's tho.

Thanks Skym always a great help.

**Skym** · 11-10-2011, 11:03 PM

Nothing wrong with stock ECU. They used it on 640hp R32GTR Group-A racecar engines. But can extract more hp by switching to aftermarket MAP ECU due to less restriction infront of turbo's (remove MAF's with gauze screens).

The intake plenum doesn't help, but it's common for RB engines to get low compression on 5th, 6th cylinders due to being closest to firewall where heat builds up and head warps. It means stock headgasket needs to be replaced with metal headgasket, metal intake, exhaust gaskets (RB26), head skimmed, etc. Some rebuild engine and fix other problems at same time.