Solution To Headlift?

[p_b82]

Hi Dan, figured i would pop a thread up on here rather than yet another one on .org....

I know you mentioned in the past possible methods and you were going to try and wire ring the block... but is\was this the only solution you can think of?

I am under the impression that this is not going to be doable for us on the L-series, from what infrmation i was passed on so that kinda limits it at the fuelling \boost side of things.

Do you have an idea of what 'safe' boost levels actually are, and also what safe fuel\toque levels are, at the higher rpm bands?

Seeing as the problem only occurs once sustained full throttle in the 3800+ rpm range is achieved i am guessing that limiting this to under 200lbsft would be the way to go..... but i am still not sure what the safe boost would be for around those torque figures, and whether a varaible\electronic boost controller would be the way to go to again reduce it up top to help ease the pressures...

Any thoughts appreciated

Pete

[E_T_V]

I try to avoid giving out answers/suggestions without the person actually understanding at least in part why i'm suggesting it.

The problem you are having is that the coolant is being forced out of the expansion cap (even with a new headgasket).

So what does that mean? Why is it being forced out?

[E_T_V]

(oh and if you need a fast answer get hold of me in messenger and I'll go though it with you there - I'm just trying not to post up advice which people don't properly understand the reasons for.)

[p_b82]

I read your posts on the other forum, and i understand your teaching methods - what i was more currious was how you were to solve it - but i now understand that this will be done for you due to the larger turbo

Thanks

[E_T_V]

Yes mine will be down to a larger turbo hot-side, however you could go down the external wastegate activated by exhaust manifold pressure (rather than boost pressure) which would allow excess pressure to find its way out to reduce the exhaust manifold pressure.

[p_b82]

Ok next question.....

What EMP would you think would be 'safe' for the L-series.

I am assuming that we are running quite high to be having problems even with the head clamped as tight as we can get away with, so we are going to try to get some readings before we decide quite how to go about tackling the problem.

custom flanges\adaptor plate and a larger turbo would be the 'best' solution i am sure, but i dont really want to suffer from lag - having driven the car when it had bad lag due to my 'non' wingy injectors i know that for me it must be on full boost before 2500rpm.

So either i go for something VNT with an electronic boost controller or we work out a way to blead off the excess EMP via the EGR hole in the exhuast manifold, with an external wastegate as you have suggested.

I guess the best way would be a piece of pipe then down to the decat, with a bit of a flex section to allow for movement.

Will that EGR opening be big enough to cause the drop we are probably after is my only concern....

[E_T_V]

EMP level I'm not sure about. I've never measured it myself. What you will see is it rapidly increases and when that happens you know you have too much gas trying to flow through the turbo. Plumb it into a boost gauge and see what results you get. I'd only be guessing at numbers but obviously the higher the worse. Obviously the higher the pressure coming out the higher it needs to be going in to get the air into the engine which would correspond with the rapid tailing off of power results with the hybrid turbos. I.e. you use a lot more boost but don't get that much more power. Because airflow gives power, not boost pressure. If I had to pluck a figure out of thin air to size the gauge then we'll be looking at something from 0-1 bar, maybe 1.5 if it is silly high.

What you'll see when you monitor it is a fairly steady but low increase in pressure with revs at full tilt until the turbine becomes choked up at which point the pressure will increase almost exponentially. Its exactly the same sort of phenomena as trying to get a standard turbo to flow 23psi. It'll do it, but it'll be grossly inefficient creating a lot of "hot air".

There isn't that much difference in the EGR diameter and the entry size into the turbo so I'm willing to bet it'll be more than enough for what we are after.

As for how to set it up, well I'd be tempted to run an adapter plate if necessary from the EGR to an external wastegaste (incorporating a pressure nipple to activate the wastegaste. Then run the exhaust from the wastegate via a plain pipe straight down and out of the engine bay. You could connect it into the exhaust to keep it quiet and tidy but for testing purposes I'd just vent it out of the engine bay to the floor. After all the only time it'll be active is when you are booting it and thus will be at speed. It'll be noisy but it'll test the theory relatively easily and will be livable day to day as it'll be quiet under normal driving.


Hope some of that makes sense, If not then yell.

[p_b82]

Yep that all makes sense...

I had read that the back pressure should be below 1bar too, but i guess it might be worth erring on the side of caution and getting something that could read up to 2 bar.

i think that the EGR is actually about 1/2 the diameter of the downpipe*.... but i can get a tape measure out tomorrow and actually measure them - Even if it is that small - i would that thought that it would be enough to relieve us of this pressure.

* re-read your post and you said entry to turbo not exit... D'OH

could a MAP sensor be used, as when looking online quickly earlier i was stuggling to find anything that would be able to cope with the heat of the exhaust gases.

I am planning on putting a 3bar one in place for the ECU to read so that i am able to get my scangauge to be able to read the bosot properly, my original one should be spare..

I am going to go out on a limb a bit and say that i think the problem is happening from around 3500-3750 onwards, but it is hard to say really as with full throttle we dont stay at those revs for long!

Also a good point about venting to atmosphere to test - no point going through the efffort of plumbing it in if it aint actually going to help, and that will save me destroying my decat

I think it will be a tad loud tho!

Thanks again though

[E_T_V]

What i'd do is either get a long coil of steel or copper pipe, e.g. brake pipe and make a pigtail of pipe from the exhaust take off. This will allow you to use standard boost tubing and a standard boost gauge rather than having to worry about high temp stuff. Remember gas won't be flowing through the pipe, it'll just be static in there allowing the boost gauge to read the exhaust manifold pressure. The other option is make something watercooled but I don't think it is really needed.

If I get time I'll make one into an EGR blanking plate and try fitting it to my 600, however my time is rather limited at the moment.

If you don't know what I am trying to describe then I'll try and draw it! (My drawing skills are rather poor hence the lack of graphics on this website).

[E_T_V]

If you want to do it on the super cheap, then I reckon I could re-use the EGR valve but would need to build some electronics to drive it to open and close at a variable pressure.