Adj Camshaft Pulley & New Cam Belt

[Sydneykid]

True.... But the retarded timing on the inlet cam should be left up to the ecu and the vvt to do. If you start messing with the standard timing and the exhaust timing this is enough. Little lone messing with the already variable inlet cam.....

You would have to disable vvt to use it properly. This would be fine if all you wanted was power or torque... VVT allows the car to have both....

I am tossing around the idea of giving this a try. The VVT advances the inlet camshaft timing, but maybe not enough. Remember it is primarlily an emissions device, so they can meet the standards and still make good power. What if the engine would make more power with more advance, but then not pass the emissions requirements? Emissions wins, power looses every time.

It is not simply VVT ---- OR ---- adjustable inlet camshaft timing

You can have both, a win win is possible

[Bass Junky]

And now SK has the requried adjustment pulley adaptor thingo to try it........

An adjustable thingo made 20rwkW jsut recently on 245rwkW car.

brought the power curve left quite a bit, top end power the same, just making the same power earlier.

BASS OUT

[Pablo]

Great thread,

I have a couple of questions;

1) What method do you use to hold flywheel still when removing main crank pulley bolt?

2) How do you fit a rattle gun on main pulley bolt with radiator etc in the way? (or do you remove to gain access?)

Thankyou

[Sydneykid]

Great thread,

I have a couple of questions;

1) What method do you use to hold flywheel still when removing main crank pulley bolt?

2) How do you fit a rattle gun on main pulley bolt with radiator etc in the way? (or do you remove to gain access?)

Thankyou

<{POST_SNAPBACK}>

1. Didn't need to hold the crank, the rattle gun undid the bolt easily against the compression.

2. You have to remove the radiator and move the air con heat exchanger foreward a little. I used a piece of aluminium (100mm X 100mm X 3mm thick) to protect the air con heat exchanger core from the back of the rattle gun. Damages the fins otherwise.

cheers

[Ben D]

SK - great thread, especially interesting for someone who's stagea is approaching 94,000 k's.

One thing, doesnt retarding the exhaust cam increase valve overlap ? I usually advance the exhaust cam if I want reduced overlap (without affecting midrange as much as retarding the inlet), such as when you're approaching the choke flow limit of the turbine and exhaust gas pressure exceeds boost pressure.

In a 4 stroke IC motor, the first valve to open after TDC is the exhaust, followed by the inlet, so if the exhaust valve timing is retarded, this must increase overlap unless the inlet is retarded too.

Hi SK,

What is the theory behind retarding the cam shaft timing?

Where are you looking for power increases, low, mid high RPM?

Cheers

Rob

Hi Rob, by retarding the exhaust camshaft timing I am aiming for more mid range, but I can get a bit of top end as well. There is also some faster spooling to gained as well. What it achieves is more complete combustion, before the exhaust valves open. Plus you get slightly higher combustion pressure, for more torque.

You don't get something for nothing though, it also means you get less overlap, the inlet valve isn't open at the same time as the exhaust valve for as long. This means the incoming inlet charge (air and fuel) doesn't help push the exhaust out. This is why it works well with a bit of extra boost (above standard) as that offsets the shorter "push" time.

It's not quite a win/win, but there isn't much downside:cheers:

<{POST_SNAPBACK}>

Edited September 1, 2005 by Ben D

[Sydneykid]

SK - great thread, especially interesting for someone who's stagea is approaching 94,000 k's.

One thing, doesnt retarding the exhaust cam increase valve overlap ?  I usually advance the exhaust cam if I want reduced overlap (without affecting midrange as much as retarding the inlet), such as when you're approaching the choke flow limit of the turbine and exhaust gas pressure exceeds boost pressure.

In a 4 stroke IC motor, the first valve to open after TDC is the exhaust, followed by the inlet, so if the exhaust valve timing is retarded, this must increase overlap unless the inlet is retarded too.

Hi Ben, what you have said is correct, overlap is simply the amount of time the 4 valves (2 inlet and 2 exhaust) are open at the same time. That'll teach me to type things in a hurry.

cheers

Edited September 2, 2005 by Sydneykid

[AlexCim]

Should i bother and buy an inlet cam cam gear in addition to exhaust cam gear?

[Sydneykid]

Should i bother and buy an inlet cam cam gear in addition to exhaust cam gear?

<{POST_SNAPBACK}>

You can't, Stagea RB25DET's have VVT on the inlet camshaft, so there is no adjustable pulley available. Bass Junky does have an adaptor ring on a Group Buy that enables you change the inlet camshaft timing and still retain the VVT. I have one but I haven't fitted it yet. But a coupe of the guys with R33GTST RB25DET's have and they report good results.

cheers

[Sydneykid]

Bump, just in case someone doesn't do an all posts look.

cheers

[lySdEXiA]

i will be doing this to an engine on a stand before i put it into my car in the near future. as it wont be in the car running, i won't be able to check the timing before and after, however it does mean i will be able to get a good clear view of all the markings. one would assume that if they all lined up, the timing would be correct, correct?

[Sydneykid]

i will be doing this to an engine on a stand before i put it into my car in the near future.  as it wont be in the car running, i won't be able to check the timing before and after, however it does mean i will be able to get a good clear view of all the markings.  one would assume that if they all lined up, the timing would be correct, correct?

<{POST_SNAPBACK}>

Ah no, you don't know where the ignition timing is now so you can't put it back to where it was. If you put the CAS back in the same postion with the exhaust camshaft retarded say 4 degrees, then the igntion timing will be retarded 4 degrees as well. This is not really a problem, just remembr to set the ignition timing as soon as the engine is running.

cheerrs

[Ben D]

Did my belt recently at 98,000 KM. Checked ignition timing before I took everything apart, the timing was around 20 degrees BTDC at 700 rpm (as SK said, probably the factory setting for the auto). Did the belt (took out radiator and starter motor, used a stop on the flexplate ring gear so I could loosen the front crank pulley with hand tools (no rattle guns here and used a bearing puller to get the pulley off). All the bearings, tensioners etc were perfect, as was water pump, just put the new belt in (kept the stock cam gears), tied everything back up, and reset the timing with an additional 2 degrees advance (22 BTDC at 700 rpm).

The car has picked up response, midrange power and also fuel economy. I put it down to the slightly increased valve overlap going back to a new cam belt (even with stock cam wheels), and the extra couple of degrees ignition advance, which I can run together with a jaycar fuel adjuster because I run this puppy on 98 RON and only at 8 psi boost. Last tank, got 450 km from 47 L (still 1/4 tank left), thats 10.4 km/L. Better than buying shares in BP or mobil. Moral: for stageas with >85 K km, do your cambelt and pick up the hidden performance benefits !

Ah no, you don't know where the ignition timing is now so you can't put it back to where it was.  If you put the CAS back in the same postion with the exhaust camshaft retarded say 4 degrees, then the igntion timing will be retarded 4 degrees as well.  This is not really a problem, just remembr to set the ignition timing as soon as the engine is running.

cheerrs

<{POST_SNAPBACK}>

[DRIFTER]

have you got any dyno results yet sk, i'll b e tuning mine soon and i'll post up the results'

p.s i always use a punch bar on the crank pulley bolt so i don't have to touch the condenser.

[Sydneykid]

have you got any dyno results yet sk, i'll b e tuning mine soon and i'll post up the results'

p.s i always use a punch bar on the crank pulley bolt so i don't have to touch the condenser.

<{POST_SNAPBACK}>

I haven't changed the exhaust system yet, but soon, as there is Magic cat (from the Group Buy) on the way. So that should push me into finishing it.

I couldn't use anything but the rattle gun as the crank would turn and being an auto I couldn't lock it in gear like a manual.

cheers

[beastien]

I've been looking at these cats from bosimporting, is this the one your talking about SK? There supposed to be the highest flowing cat on the market 706cfm.

[AMS]

I'm awating that group buy then sk...

[Sydneykid]

I'm awating that group buy then sk...

<{POST_SNAPBACK}>

The Magic cat Group Buy is still open I think, check out the Group Buy section. I sent Magic a sample cat so that they could make bolt ons. Spend $260 and a few days later the cat arrives, jack up the Stagea, undo 4 bolts (and the cat overheat sensor if it is still there) and swap them over. The longest part of the job is the jacking up and placing of the stands.

Except I have to swap the exhaust (cat back) at the same time, that will slow me down some.

cheers :

Edited December 6, 2005 by Sydneykid

[AMS]

Yeah unfortunatly the group buy is closed So I will just have to pay retail I suppose....Meh - or wait for another one

Edited December 6, 2005 by AMS

[Sydneykid]

Hey if you give them a call and mention the group buy, or go in and mention the group buy as long as its soon they will look after you.

<{POST_SNAPBACK}>

Edited December 6, 2005 by Sydneykid

[AMS]

Yeah I had read that...But I'm not sure whether I want it just yet. Have to spend my dollers on getting her registered etc. first