Variable Inlet cam, samples being made, I need a tester.

[Bass Junky]

Hey guys.

As you may know, I recently fitted some cams to my car, which resulted in a slight loss of power blah blah blah.

Something I did find out however, is that you can actually adjust the inlet cam gear, but only from the back of the gear. That is the part which you can only get to by removing the cam gear itself.

In the name of power hunting, I'm making up a flange which I am going to fit to my car to enable the gear to be adjusted from the front of the gear, making it really easy to do.

I need, however, a guinea pig to have a go with their car.

I know that one of my mechanics has done this on am RB, he was using Wolf I think, and he reported pretty reasonable gains.

So, what I need is somebody who is keen to fit one to their car and report back on results.

I will have some samples this week....

Who is interested?

BASS OUT

[Kaido_RR]

sound interested if it wouldnt blow up my engine , i will be up for it. the wa boys are holding a dynoday with saturday so if you could get it to before then i might be able to get abit of adjustment done and dyno results for you by next week,

ps, i got an rb25det s1 r33 1993

[DivHunter]

How much adjustment is in it? What kind of dyno time do you think would be needed to test this properly?

I'm interested but obviously how much it would cost me for very little (stock car) to 0 gain is of concern. Would be best to get a few people with cars at different stages to see where it is really handy. Will be getting a base power run on a DD dyno on the 19th regardless.

[Bass Junky]

Well, you can feel the difference by the seat of your pants (apparently) with the adjustable exhaust cam, so I would assume you would be able to feel some difference by adjusting it all the way one way or the other.

I will be having mine done, and driving straight to a dyno for playing next week.

I wont be able to get it to W.A by this weekend though.

Where are you located GTS?

[Kaido_RR]

im in perth

im guessing we are looking at a max of 30 to 1hr of dyno time by the sounds of it so about $60 which is ok with me

[Bass Junky]

So NOBODY in Melbourne is keen at all?

[Sydneykid]

Some things I have experienced, might be worthwhile thinking about.

The usual adjustment (noting that every car is different) on the exhaust camshaft is 4 degrees (retarded). The inlet adjustment is 1 or maybe 2 degrees (advanced), some engines like to run on 0 inlet can timing. Then the power gains, I have seen as much at 15 rwkw from adjusting the exhaust camshaft timing. But I have never seen more than 5 rwkw from adjusting the inlet camshaft timing.

So be aware of the cost per $ equation when designing the inlet camshaft adjuster:cheers:

[Bass Junky]

Yeah, I knew there wasn't a huge amount of difference, but I just want to try adjusting my inlet because there is adjustment available in the stock gear, and it is all the way to one side. Not sure which side as it's back on the car now. If it's retarded by it's full adjustment, I'm definently going to pick up a little bit, if it's fully advanced, maybe I need to back it off a little.

More for curiousity than for outright power searching.

SK, have you even adjusted the standard inlet cam on an RB25DET? Just curious if you know why there is adjustment as standard, cos the exhaust isn't adjustble....

All help appreciated.

PS, the adjuster will be a really really simple piece of laser cut 6mm plate with four holes tapped into it.

BASS OUT

[StockyMcStock]

so sydneykid, from all the R33 GTS-T inlet cam gears you have seen, whereabouts should the screw sit in the adjustment arc? middle? to one end fully?

edit: haha beat me to it!

[Sydneykid]

so sydneykid, from all the R33 GTS-T inlet cam gears you have seen, whereabouts should the screw sit in the adjustment arc? middle? to one end fully?

edit: haha beat me to it!

Well 1 or 2 degrees is not much of a change from zero (standard) so they are in the middle, just a little advanced (that's clockwise). The following picture is the HKS exhaust camshaft pulley on the Stagea set at zero, as you can see 1 or 2 degrees wouldn't move the bolts much.

[Bass Junky]

Would 2 degrees retarded have much of an effect in the inlet cam?

[StockyMcStock]

so IYHO for an RB30DET running 15psi, how should i assemble the inlet cam? right in the middle at zero, or advanced a bit?

[Sydneykid]

Yeah, I knew there wasn't a huge amount of difference, but I just want to try adjusting my inlet because there is adjustment available in the stock gear, and it is all the way to one side.  Not sure which side as it's back on the car now.  If it's retarded by it's full adjustment, I'm definently going to pick up a little bit, if it's fully advanced, maybe I need to back it off a little.

More for curiousity than for outright power searching.

SK, have you even adjusted the standard inlet cam on an RB25DET?  Just curious if you know why there is adjustment as standard, cos the exhaust isn't adjustble....

All help appreciated.

PS, the adjuster will be a really really simple piece of laser cut 6mm plate with four holes tapped into it.

BASS OUT

Sorry I have never adjusted the inlet camshaft timing on an RB25DET with standard cams. Only ever done it when the VVT was removed and aftermarket cams used.

I think it has an adjuster standard to allow for stretch in the cam belt, this would retard the inlet camshaft timing, which is not a good thing. Inlet camshaft timing has a big effect on emmisions, so maybe Nissan allowed for its correction to ensure emmisions compliance. That's my guess anyway.

[Sydneykid]

so IYHO for an RB30DET running 15psi, how should i assemble the inlet cam? right in the middle at zero, or advanced a bit?

I would give it a try at 1 or 2 degrees advanced, but every engine is different.

[Bass Junky]

I think it has an adjuster standard to allow for stretch in the cam belt, this would retard the inlet camshaft timing, which is not a good thing.

So in the case that I had a new belt fitted..... Timing would be back to original or something?

Bugger it, I'm just going to fit the thing and have a play!!!

[Bass Junky]

Inspired by SKs pretty pictures, I have taken the following few pics for your viewing pleasure.

You can see that the amount of adjustment is quite large, maybe 10 degrees total.

I noticed that the stock location of this particular gear was almost at 0 degrees.

I will be making the spacer/adjuster this week some time, just depends on when we are getting our next run of 6mm plate laser cut.

Enjoy

[Bass Junky]

Okay, after much buggerising and me being too busy, I have 3 samples to sell.

$40 is the price. They are laser cut and marked, and hand Tapped.

Each will be fitted to a pulley I have here to make sure it is a nice fit.

Freight will be $15 via TNT if you aren't in Melbourne.

Let me know.

[GTRgeoff]

So since this was so easy Pete, why not take the next step and start having the standard exhaust cam gears machined out and fit a machined bracket to provide a budget exhaust cam gear?

[Trust33]

Yo bass!! why dont you get the std exhaust cam gear going as well?

Or is it impossible with the way they are made.

[Bass Junky]

It is possible.

But by the time you make up the spacer ring AND machine the stock cam gear, you are talking about the same sort of money as a nice shiny, lightweight HKS cam gear.

The slots need to be machined on the radius, which means CNC, which means to do it properly you need a whole crap load of them and I ain't got more than one!