Cam Timing For Supercharged Gti6 Engine

[stef205 92 1 Cars]

I need to check the cam timing on my charged engine, does anyone know what it should be, it might be possible that I'm loosing boost through the exhaust.

 

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Edited September 6, 2012 by stef205

[welshpug 1,657]

Just set it to standard, that's all the Lynx kits run, you could advance the inlet a few degrees but have to be very careful especially if its not known how much has been taken off the head.

[kyepan 291]

Unless you had an extreme amount of overlap on the exhaust stroke, i would not expect you to be "loosing boost" through the exhaust valves. You would notice this quite clearly as it would stink of unburnt fuel, and an MOT emissions test would be off the scale. In standard form there is very little degree of error on gti-6 engines before valves start hitting each other, especially on overlap.

 

I'm guessing you are not seeing the boost you were expecting?

[stef205 92 1 Cars]

No I'm seeing 3-4psi should be about 6-7psi. I think I will set it to standard I'm sure it can't do any harm to check. I plan to have a great in depth look to see if there is a boost leak.

 

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[kyepan 291]

if you have a boost leak that is letting go of half your boost, you would hear it, because of the volumes involved. It would sound like a pissing great whistle, have you checked the waste gate (showing my ignorance here, not even sure how superchargers vent excess boost) to make sure it's not been fettled with and or is stuck open / closed / half open?

[dcc 855]

make sure your lower pulley on the crank is either a brand new gti6 item, a solid after market item, or use a 8v item to 'time up' the engine correctly. you will be pissing into gale force winds otherwise.

[stef205 92 1 Cars]

I pin the flywheel I never use the crank pulley. Ive got 2 Bosch recirculating valves for dump valves, I'm wondering if these are leaking there off the a Saab 2.0/2.3 turbo.

[petert 586]

Inlet standard and aim to advance the exhaust cam to approx. 0.020" lift @ TDC

[kyepan 291]

Perhaps try blanking both off and test.

[wicked 103 3 Cars]

To check for air leaks on your inlet circuit, you can use this kind of device:

 

 

 

You replace your air filter with this tool and connect the air valve (pin on top) with the airgun of your air compressor that you use to inflate your tires.

Then you 'inflate' your inlet to a 1 bar. If you've a leak, you'll see the pressure dropping on the gauge of the airgun.

(make sure that no piston is in TDC with both inlet and outlet valve open)

 

Leaks are also easier to find if air is blowing out of it....

Edited September 7, 2012 by wicked

[stef205 92 1 Cars]

That quite a good idea, may look into that

 

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[madspikes 41 1 Cars]

When I first put mine together I had a few leaks, didnt lose too much pressure 1psi or so. I had pin hole leak in charger outlet, that whistled. I also had alot of trouble getting the charger outlet flange to seal with the charger, the best solution I found was to use a cork gasket, worked a treat.

 

Check everything that is connected to the inlet is geared up for taking boost and not just a vacuum.

 

Might also checking if the map sensor is actually reading correctly. Where is the map sensor installed?

 

Did you check the rotors on the charger before you installed it?

 

Mad.

Edited September 7, 2012 by madspikes

[stef205 92 1 Cars]

Hi mad,

The map sensor is working fine as it was mapped with it. I think that's where mine maybe leaking I'm currently making up a boost leak tester to find the leak once and for all. Does seem odd I'm only getting 3psi, 4 psi at 7200rpm just

 

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[madspikes 41 1 Cars]

Which charger are you using? What are you making at full throttle at say 3500 rpm?

 

Mad.

[stef205 92 1 Cars]

Its a m45 and it makes about 3 psi.

 

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[stef205 92 1 Cars]

Ok so I have made up a tester. I will set the compressor to around 1 bar bit less and connect it to the tester. Hopefully this should show up any leaks in the boost system. Before I connect it has anyone any do's and dont's? I'm going to remove the oil cap to release and crank pressure etc, and make sure the tb is shut? I do know I have small leak on the tb where the heater element would be.

Any input will be great

Edited September 8, 2012 by stef205

[wicked 103 3 Cars]

Seems ok; my post was not completely correct; we indeed put it in front of the turbo (compressor inlet), not exactly at the air filter location; so the breather hoses attached to you inlet circuit don't see pressure. TB should be opened a little; you want to test the complete inlet circuit!

Note that you'll indeed lose pressure via the engine, even if you don't have leak, but it should be able to escape via the breather hoses.

 

As said, make sure that the pistons are all about equal height, (= no valve overlap)

 

Edit; might be better to use an air valve from a tire; that are one way valves, so you can pressure it and keep it silent to hear were the leak is. Now your compressor will keep it on pressure and air keeps flowing in (if you've a leak) and you won't hear where the leak is..

Edited September 8, 2012 by wicked

[stef205 92 1 Cars]

I plan to turn the regulator down on the compressor and have the tank full so it doesn't need to be on. I did think about that with the pistons and I will have the tb open abit to also test my inlet.

 

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