CJRH

Having recently had the PPP fitted to MY99 and also a boost gauge it is now quite obvious how much the air temp and density make to the amount of boost. What is the best way to overcome this? My first thoughts are on fitting a water spray kit for the intercooler. Does this actually do much? What are the other alternatives? Bear in mind the amount of money I have just spent on the PPP I can’t go mad!

Cheers Chris

john banks

Firstly, don't know! But I have noticed that the held boost is virtually always 16.5PSI, as long as it reaches that on spool up. The peak can be up to 17.5-18PSI with my current 1.35mm restrictor. Sometimes - if foggy, cold and wet like last night it holds for a very long time - like a few seconds before settling. Feels great but if it holds too long then the ECU pulls things back and the boost momentarily drops to 14PSI before boosting again. Certainly does this on 1.3mm restrictor - with 1.4mm it only ever reaches 15PSI, so my current on is made by "wiggling" the 1.3mm drill a bit! Works though. I have set things so that it peaks as high as possible on the cold foggy nights without fluttering. BTW I have a DP - before that 1.3mm was fine (originally 1.2mm).

CJRH

John, not wanting to sound to thick but what and where is the restricter? While we're at it what does the acturater do???
Engines like the V8 in my Landy special I find easy but turbos and the other bits surrounding them, not a clue!!

john banks

I will make a mess of the explanation but try anyway. Just at the junction of the blue Prodrive hosing and the intercooler there is a nipple onto which a black four inch long 1/4" hose is attached which has a bend in it and then goes into a T-piece. JUST before the T-piece inside the pipe is a tiny brass restrictor with a hole in it. Beyond the T-piece and other paraphenalia is the wastegate diaphragm which responds to the pressure in it opening the wastegate relieving excess boost so you don't boost into oblivion. With no restrictor in the pipe, the boost will only go up to about 10PSI. If there is a restrictor in of the correct size, it will reduce the pressure that the wastegate diaphragm sees, so allowing boost to peak above 10PSI - usually for PPP about 17/18PSI. The ECU then stabilises the boost at around 16PSI using data from the MAP sensor, and has some control over the wastegate by altering pulsation frequencies.

If you have a Link or Unichip, I heard you can program water injection into it. But there is no such facility with PPP, and unless you were to do it manually, or fit a controller to do it at the right time it could be a lot of faff. I would have thought that rather than spraying the intercooler you actually want to cool the charge - ie water injection to get most benefits.

If you have not already fitted a decat DP I would highly recommend with PPP, but your warranty will probably be invalidated. What peak/held boost are you getting?

CJRH

John originally I was holding 16PSI with not much peak above that. This seems to have dropped a bit down to 15PSI. This was why I was wandering about out side influences ie. air temp.
By fitting the down pipe what is the likelihood of doing any damage? I ask this because I once had a Piper Cross induction kit fitted which promptly broke the MAF sensor. This has made me wary of messing around with the engine.
When the MAF sensor broke and left me stranded by the side of the slip road to the M3 (didn’t even make it onto the motorway!) the brake down driver who came out was a young Kiwi. He said that in NZ they just adjust the Actuator to increase the boost, have you heard of this??

Cheers Chris

john banks

Changing the DP on PPP cars seems to be safe and very good, certainly with no danger to MAF sensor, and no problems with knocking/lean running etc. Induction kits are debatable, but I run a K&N on the basis that no-one on here has had MAF issues - possibly related to vibration or oil particles. But if you change the DP, you may have to increase the size of this restrictor to keep the boost in check - but I had to have this done after PPP was fitted anyway.

The figures I give for my boost are the best, but usually in 2nd gear or up I can achieve 16PSI held no matter what the conditions. Perhaps it would be worth finding out what size restrictor you have in as you may be able to get another 1-2PSI of held boost if you are only hitting 15. But you need to set it when it is cold and foggy, otherwise you will overboost.

Someone did mention adjusting the ?tension? in the actuator, but I've not looked into it in detail. I think it is fair to say that unless you fool the MAP sensor it is difficult to increase held boost with a PPP just by fiddling the plumbing as I believe the ECU sets the held boost using the MAP sensor. You can easily adjust the speed of spool up and the peak boost with the restrictors. In fact I have not been trying to extract more - more that after the DP it was boosting too much and I have just tried to get the levels more sensible so it is smooth and the boost does not oscillate during prolonged acceleration in 4th/5th gear.

If you want to see peak boost try flooring it at about 3500rpm in 4th or 5th gear, and then you might see a little peak with your current setup.

[Edited by john banks - 10/15/2001 4:34:42 PM]

CJRH

Cheers for all of that John. I'll have a play around tonight and see if I can't measure the internal diameter of the restricter.

Cheers Chris.

john banks

Maplin have a drill set with 0.1mm increments which is probably quite handy for fiddling.

dowser

John

I *think* most people don't have a problem with just the PPP - only when you change the d/p & induction too, and even then some don't (or don't notice - I wonder if we would if it wasn't for the boost guage ).

I'm currently running a standard restictor with a 1.2mm drill bit 'wiggled' through it.....and 9 virgin items ready for the cold weather

Did you have any luck with the adjustable valve?

Cheers
Richard

john banks

Not got it yet. I've been trying to contact Richard Hargreaves about it.