Inlet Cam Adjuster Dyno Result

[Bass Junky]

Hey guys.

Well, a little while ago I discovered that there is an allowance for inlet cam gear adjustment from the factory.

For some reason, possibly emissions etc, Nissan has handily made the VVT assembly adjustable, but it is very hard to do, involving removing the pulley each time you want to adjust it.

That is until I made up a ring which, with slight modification to the standard pulley allows adjustment from the front of the engine in a matter of seconds; with the cam gear cover off of course.

Now, until now, nobody had tried them on a car with any sort of dyno charts to prove anything.

Until now.

On the weekend, an R33 which shall remain nameless, and a workshop who shall also remain nameless tried one of my little wonder rings, and made some fairly significant gains by advancing the inlet cam a little.

The peak power remained the same, but the power through the rev range was increased by a very reasonable amount. How’s 20rwkw sound?

In the lower range, off boost, power was also increased, and then when the car began to boost, power was up everywhere.

The power flattens out at the very top, but stays up and doesn’t nose over.

Car has following mods. Intercooler, highflow turbo and Wolf3D and other supporting stuff.

The procedure with the tune was as follows.

Adjustable exhaust cam gear was added, power run up. Exh gear adjusted to about 4 degrees. Pretty standard stuff on an R33.

The top made was the Black line.

Then the inlet cam gear was adjusted. Can’t say how much by at this stage.

But you can see, with each amount of adjustment, the power curve moved across, until the final one made the 20rwkw at about 4500rpm

Nothing was changed on the tune, no adjustments were made with timing or anything.

Just the pulley was adjusted.

The VVT was still active, and the changeover points, to my knowledge, are very close to stock, they were only adjusted to fine tune the turbo.

Obviously soon, I will be spinning my car up and trying it with a stock turbo but with Tomei Poncams, and seeing what we can see.

Also, I will be making the adjusters up to a commercial quality, with adjustment marks and zinc plating them for longevity, and a batch will be made up.

I would like somebody in Melbourne to try one of these with stock management and stock turbo etc just to get a grip on the power gain possible with everything stock. I will supply an adjuster free of charge, but I will need you to spin the car up on a dyno, which I can arrange in Croyden.

Any volunteers?

Here’s the dyno charts, see for your self and make your own decision.

[Ronin 09]

interesting Bass

if this car has a Wolf, why are the AFRs so... special?

or is this something to do with the VVT?

keep up the good work

[Bass Junky]

Ignore the AFRs.

The Dyno sensor was up the shit, they were using their own seperate probe.

[shanef]

How much it cost you to fabricate this?

Also how long it take?

[Bass Junky]

Well, the final cost isn't down yet, as for the prototype was hand tapped and not zinc plated and hasn't have any markings on it.

The commercial ones will be Laser Cut, Laser Etched and CNC Machined, or just CNC Machined and then Zinc Plated.

Gotta work out the numbers.

Probably at this stage they will be Laser Cut, Laser etched and then CNC machined. Maybe I will have the markings CNC machined, and then the finished product will be plated.

To fit up, I would say about an hour or so.

You will need a 6mm drill bit, pedestal drill and a couple of hours I guess.

Gotta pull the Cam cover off, remove inlet cam gear and VVT stuff.

Drill out the existing M6 tapped holes.

Put adjuster plate on the back, screw in four bolts from the front of the Cam gear.

Adjust so adjustment is in centre, or where the pulley was to start with.

Lock everything up nice and tight. Real tight.

Reinstall inlet cam gear, and all VVT stuff.

Then, you are ready to adjust cam gear.

If you were serious, you would probably spin it up on the dyno and play with the gear until you are happy.

The best part is that to adjust the gear, you simply loosen the four bolts, adjust gear, and tighten back up.

Not like the exhaust cam gear where you have to remove and replace the damn CAS everytime.

BASS OUT

[paulr33]

love your work

[R31Nismoid]

paul... you shuold volunteer

[Dr_Drift]

Paul - You should volunteer... I will discount dyno time to help provide an unbiased result for Bass... Sounds like an excellent solution...

Doc

[Bass Junky]

All in favour?

[Dr_Drift]

AYE

[raz0r$harP.UK]

Interesting..very nice gains.

Do you have any ideas / thoughts on how much noise and emissions change as a result of this mod?

[Bass Junky]

I'd have absolutely NO idea.

[nitemare5]

i might get my mate who owns my old r33 to give it a run if dr_drift is willing to give discounted dyno time - i think dr_drift is familiar with the vehicle too. i'm very interested in the results of this, good stuff bass!

[Dr_Drift]

More than happy to... Bass is a nice guy and would be good to see some independant results.

BASS - I may even be able to hook up a free new product mention in a magazine for you?

[Bass Junky]

Sounds good to me.

Check your e-mail Sam.

[paulr33]

hey if you guys reckon it will work and its safe to do so then yeah i guess we can try it. im a bit scared but theres no benefit without risk taking. when do u want to do it. what do i need to organise? pm us bass when you are ready if yous want me to trial it

[Bass Junky]

I have a few of the adjusters in stock.

The question it when do YOU want to do it.

[Sydneykid]

Interesting..very nice gains.

Do you have any ideas / thoughts on how much noise and emissions change as a result of this mod?

<{POST_SNAPBACK}>

Noise???? Based on the 2 degrees advance we apply to GTR's and RB20's, it doesn't make the idle "lumpy", if that's the question. They just sit there and idle, same as they did before.

Emmissions, that's a bit tougher to answer as it depends on how the engine is tuned before the inlet camshaft timing is advanced. Just fitting an exhaust and turning up t he boost to 10 psi makes an RB25DET fail the ADR standards. I suspect if you advanced the inlet camshaft timing 2 degrees on a totally stock engine it would make bugger all difference to the emissions, with NOx being the only question.

cheers

[Dr_Drift]

I'm booked till 22nd August... We can do it then if yo like Paul??

[paulr33]

fine by me, bass pm me when you have a sec

also theres no major reliability/damage that should occur?

just dont want it to go bang