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Some of this week's Letters to AutoSpeed!

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Three Means Trouble?

Hi all - congrats on the mag. I've a query regarding the EJ20 turbo, specifically the unit in the GC8. Here in Ireland and the UK we have had some trouble with bearings letting go - most common seems to be number three. Theories range from poor fuel, higher temp (due to location beside the turbo), bad service practice and even poor airflow into scoop at high speed. Is there a pattern of failure in Oz Rexes? Are there any upgrades that should be carried out on a standard Rex (ie old Cossies needed to have an upgrade fuel pump)? Cheers

Fergal Chambers

Cylinder number three - the one nearest the turbo - is almost invariably the cylinder that gives trouble in GC8s. There are numerous theories, but it seems the problems are linked to lean mixtures and/or detonation in that cylinder. Number three is the last cylinder to receive fuel from the rail and we've heard any drop in fuel pressure means it starves.

The best measures you can take are ensure there's adequate fuel flow at all times (perhaps using an electric fuel pressure gauge in the cabin), ensure the number three injector isn't clogged, use the highest octane fuel available (hopefully better than 96RON) and keep intake air temperatures as low as possible. It's also a good idea to check the condition of the hose connecting the intake manifold to the fuel pressure regulator - these can split with age, potentially reducing the manifold pressure applied to the regulator and, therefore, causing lean mixtures under load.

LS1 Oil Glugger?

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In a number of articles on the Gen 3 engine you refer to an oil consumption problem. Having just purchased a low kilometre example of this engine to go in my Cobra replica I was concerned to find traces of oil in the inlet manifold. Can you tell me more about this oil consumption problem and what is the fix being used by GM? Thanks

Phillip Neall

Traces of oil can be found in the inlet tract in many engines - even relatively new ones. Unless the engine is consuming a fair amount of oil we wouldn't stress too much. If you happen to be using Mobil 1 at present, we've been told oil consumption is reduced if you use slightly thicker oil. You might want to give that a go. As far as we know, Holden perform a rebuild on Gen 3s that have oil consumption problems (those that are still covered by warranty).

VL-T Versus VR6

After freeloading off the AutoSpeed articles for some months I finally bit the bullet and subscribed. I can only say that you are a breath of fresh air compared to the rubbish published in most magazines. As a subscriber could I trouble you with a question? I am moving from an auto Rex to something cheaper, manual and exciting. My shortlist is VL turbo and VR6 Golf. The VR6 has dropped to under 20 grand and all reviews seem positive, but I am worried about outgrowing 127kW. Any views you may have would be appreciated.

Spiro Politis

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Take it from us - the VL turbo is a big step backward from a WRX. Don't forget, the VL Commodore is now about 15 years old and, inevitably, they feel it. If you're interested in making a few basic mods and going fast for little money, however, the VL-T is a great platform.

Realistically, though, you'll find a lot more pleasure from a Golf VR6. With 8-second 0 - 100 performance (in manual form) they're virtually on the pace of a well-kept standard VL-T. As you implied - like any car - the VR6's stock power output might get boring after a while. The biggest problems with the VR6 are limited scope for enhancement (what go-fast gear is available for VR6s in Australia?) and uncertain resale value. Oh, and parts will obviously be a lot dearer than the VL...

For less than 20k, you should also consider the turbo Lancer GSR, 200SX, GT4 Celica, Liberty RS, Galant VR4 and a number of Japanese imports. There's plenty to choose from!

Mega RB

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Hi guys - I own a R33 Skyline GTS25T automatic and have decided to go for a RB25/RB30 hybrid engine. I have recently met someone who did most of the work by himself on a similar car and managed to squeeze out 345kW at the rears. He uses a massive KKK turbo, custom plenum, and all the rest of the usual goodies. The car underwent an auto to manual conversion and uses a R32 gearbox with fabricated bell housing.

My concerns are, if I go this way, should I use the standard R33 gearbox or go for a S15 6-speed? Would it be better to stick with auto and get a tricked torque converter (like the Trimatic trans used in the SubZero car)? What about a bigger LSD replacing the viscous factory one? And how about plenum design - GReddy v Subzero v Nizpro one? Lastly, I have a mate in Japan who will try to get most of the parts for me - should I consider a RB26DETT head instead? Any suggestions?

Amrit Ram
New Zealand

The optimal driveline depends on the torque characteristic of the engine you build and your intended application. If you're planning on coming near 345kW at the back wheels you're invariably talking about a massive single turbo and lots of lag; in this case, an auto with a high rpm converter has its advantages. An auto will allow you to stall the engine up for fast launches (it's difficult to launch a big turbo'd engine with a manual 'box without either massive wheelspin or bogging down) and it will also kick-down by itself, making the car feel livelier in traffic. The biggest problems are noise and fuel consumption (lots of revs everywhere you go). Oh, but your standard R33 trans won't be able to hack such huge power - something like the beefed up Trimatic should capably handle the grunt.

We're not sure about the limits of the Nissan manual gearboxes, but we'd imagine they'd be pretty marginal at that power level. A drag-oriented auto is likely to be the more trouble-free approach. With this amount of power you'll need to find the most possible traction using, of course, sticky rear tyres and probably a locker type diff centre. See how you go durability wise using the standard type diff - a tougher unit may be required depending how hard it's treated.

No idea which intake plenum is better - you'd need to compare side by side on a dyno to judge. Any parts from a Skyline GT-R engine are ultra expensive - see how you go bolting all the good gear to your standard RB25 head. If you're not satisfied with the power, you should look into a GT-R head as a final phase.

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