Vic Rattlehead

Hi all.

Recently fitted a VDO mechanical boost gauge. WOT in 3rd 4th and 5th is showing 12psi.

Now, I was thinking I'd be seeing more along the lines of 15psi, with the modifications on the car.

Lyndsey boost enhancer, 3bar fpr, promax chips and bailey blow off valve. This was already fitted when I bought the car two years ago and it looks like the previous owner wound out the boost enhancer to nearly it's maximum, did a quick search on here and I've read that the factory 10psi is around 4 visible threads.

So anyway, I've just done the wastegate test and clamped off the line from the intercooler hard pipe as I read this is acceptible as clamping off the line from the CV to the wastegate and got the same results, which is leading be to believe the wastegate is dead.

I was wondering if anyone here had done the wastegate test clamping the line from the hard pipe. Or is it not as reliable as clamping the line from the CV

Also, the VDO gauge isn't wired into a switched 12v yet, I'm assuming as it's a mechanical gauge it wouldn't need power to work correctly?

If the wastegate is dead, it'll give me a good excuse to purchsase a Tial

Cheers in advance.

User 41221

The switched 12v is just for the light on a mechanical boost gauge, so you are correct.

As far as troubleshooting boost goes, if you are running the stock cycling valve, I'd tend to think that is the first culprit, but you are going to need to do a methodical testing of entire system before starting to throw parts at it. I will say this tho, if the wastegate is original, getting a TiAL or Lindsey DP is a good first mod. If future mods are in the plans, I'd seriously look at that and a black **** boost controller, and eliminate the factory CV and venturi system.

[EDIT: Correction, I was thinking 1.2 bar on the gauge when I said the stock CV was the culprit, which would indicate basically no boost. Showing 12psi on the VDO gauge, doesn't change the basic advice I gave you, tho I would eliminate the CV as teh first place to look]

teamcrossworks

Stock wastegate spring is getting tired and/or valve seal is leaking...the LR boost enhancer does not increase total boost just when it is delivered. Rebuild or buy a new one from Lindsey or Tial.

Willard Bridgham 3

First check the wastegate.
If you still have the cat, check the cat for fouling.
Also check the downpipe from the turbo.

Oddjob

Another possible cause of the symptoms - helped trouble shoot a car that would only make about 8-10 psi even when WG line was clamped. Thought it was the WG, plugged cat, collapsed x-over or down pipe, etc. - but then found this:

Vic Rattlehead

Excellent. That's great guys.

I always thought that the LBE wasn't a boost controller as such, only a method of delivering the factory boost earlier. Just read posts over on Pelican that seemed to contradict this.

Tial 38mm wastegate, black **** boost controller and chips are the next in line. Along with a cat delete and new exhaust. Just will be next year until that happens.

As it is, the car is pretty brisk so I'll be happy to wait until then.

Cheers

dillon410021

cracked crossover pipe?

Vic Rattlehead

Ouch Jim.

Foreign object flying around in there?

Really hope I wont find that if I pull the throttle body.

Dillon. Crossover pipe looked good when I changed the coolant a month or so ago. I'll have a closer look though.

Willard Bridgham 3

I knew a mechanic once who poo poohed when he dropped a washer/screw when he had the turbo inlet off. Turbo, turning probably 100k rpm ate the hardware. Compressor looked a lot like the picture.

No accounting for fools........

User 41221

And a nice bunch of metal shavings getting sucked into the intake really helps the leakdown numbers too...

Black51

If you don't have a boost controller, with the CV bypassed, you'll never see 15psi.

And +1 for what teamcrossworks said.