Martin Donnon

My One Tonner is having a V7YSi geared for 25psi boost being fitted at the moment

V1 T Trim

Thanks mate. Its CAPAs car, Ive just been doing some tuning stuff on it. The poor thing as 3000km on the clock, all of which have been generated going to and from V8 Supercar rounds as a dedicated burnout car. It was born at the start of March, went to Clipsal, Puke in NZ, missed Darwin, and is now on the way to QLD for the 400 (?) on this weekend. All stock save for the blower and a clutch. Been through masses of rear tyres, and is very liberally coated in rubber. Not bad for an inferior quality, poorly built, badly engineered pile of poop eh? With 120rwkw it would probably last 25 years. Food for thought.

So the old Falcon won by about 150rwkw? WTF? Thats not even sport!

Out of interest what did PCOTY make on that dyno? And the turbo Toyota Crown?

I was genuinely surprised how gutless most of the cars were there. Where are all the tough GTS R32/33s? GTRs? 120rwkw S15s just dont cut it.

Am I allowed to enter an XR8?

So Wiplash, you going to enter your real power-house, or just the red car?

Could you build me one of these please?

Look Steve for a mild mannered road car like yours, you havent done the wrong thing. Most off the shelf Jap cams are extremely mild though. Like the 256/256 HKS sticks I put in my Soarer made like 10rwkw for $1000. Nice. Not. Im writing about maximum effort engines rather than roadies, however, if you have the tuning ability then unconventionally large camshafts can be made to run sweetly. Heard Keirs engine idle? Put an exhaust on it, and the thing would sound almost stock. As an aside the Japanese aversion to large camshafts would more than likely be due to their lack of tuning tools to make them run correctly. Ie. the same reason they change GTRs from six throttle bodies to a big single, when the single has less cross sectional area than the stockers.

Think outside the square for a minute, and put down the keyboard and engine simulator. They are great for a ballpark reference, but are based on the same - what I believe to be outdated - principles, and old wives tales that hampered traditional V8 camshaft selection for years. Now these same rules of thumb are making their way into DOHC circles. In nerd talk, GIGO. Now step into the real world and have a look at the engines that are making truly huge horsepower, and running enormous trap speeds. Worry not of their inlet duration, claimed exhaust numbers, or even lobe separation. These are rough, rule of thumb figures that give and indication of the camshafts design, rather than tell the whole story. The true power comes from the actual valve events that take place in reference to crankshaft rotation. Then theres the lobes themselves. No duration figure will explain the ramps. If you have a basic understanding of this discussion, and knew the sorts of camshaft numbers I am talking about, then you would be awestruck. There is no theoretical simulator or text book in the world that would recommend you use them. But, they work. My recommendations? Concentrate on the inlet more than the exhaust, after all, this is where the exhaust energy comes from. Ask most of the gurus around the traps about this, and most of them will simply shake their head "nup, cant work". Then ask them how a camshaft actually works, and they will give you a blank look. Twiddling around with an adjustable gear does not instantly convey understanding.....Unfortunately for 99.9% of camshaft selections in Skyline engines, picking an old fashioned profile out of a book is as technical and sophisticated as it gets. Sure they work, BUT they could work MUCH better. There is only one LSA ICL and ECL that works perfectly for any given engine and turbo combination. The closer you get to that, the more power and torque you make.

While that may be your experience, common physics would tend to argue with that. Think for a moment of whats really happening when you change cam gears, rather than the shiny gear itself. Effectively you change the LSA (Lobe Separation Angle) of the camshafts, and alter the opening/close valve events of the exhaust camshaft. You would need to have a look at the real effects this has on camshaft timing using a degree wheel. What you would find if you did this is an effective shortening up of the exhaust time for the camshaft when you dial 5 degrees into the exhaust (and thats a lot). The bottom line here is that for a power gain to happen from this modification at the top end of the rev range, you will essentially have to lose cylinder pressure and response through the 0 - 4000rpm mark. This can however be effectively made invisible during dyno testing with a combination like yours due to selected dyno ramp rate, or turbocharger response. On the road? Its a whole different story. Remember the simple principle with this cam timing process you describe, that being there is no magical gain to be had, rather you are equipped with the ability to effectively move the powerband of the engine around the rpm range....within limits. .....All of which is why the correct solution, rather than the 'nickel & dime' solution is to pick the correct camshaft profiles for the application in the first place.....Try something like a 262 inlet with a 256 exhaust installed at 114ICL on your engine, and your eyes will drop out of your head!

No mate, you've said it all............. You win!

I want to buy your roll cage when you sell the car......at least I know it will never be close to being used!

And who said you werent a Rice Boy Steve!

Old Commodore VH Trimatic

Too often!

Treaded tyres only on a Wednesday night

Well Andrew, you are wrong Last night, on BF Goodrich Street Radials they went 10.24 @ 138mph. If they had persisted it would have gone into the 9s, but were happy with that and went home...

Its nothing, just replacing the tired old RB25DE in my clapped out roadie, with an RB26DETT, Nismo turbochargers, GTR rear end, and putting a factory auto behind it. Nothing too extreme

Ill do it next meet, there simply arent 'enough' of the 13 second club going. Im going to be busy working on the GT S15 anyway. Thanks for the offer though. Next time!

Im having problems finding one runner, let alone three!

Well Matt, let me know for sure. That would be good Martin

Really it would have to be someone like Matt thats experienced out there. First timers have got enough to do trying to get the procedure right without driving the Gtech as well!