Adjusting Turbo Pressure Step by step

[visotzky]

I installed a guage today and it was maxing out at 7psi, The problem is that after making an adjustment it blows off before it can hit 10psi, Shouldn;t be 15 psi? any ideas?
ps is the boost related to rpms? and would that increase at highway speeds? I seam to get more boost at highway speeds verses 50km at similar rpms. I have a manual transmission.
Cheers
Val

[DelicaMark]

Hi Val,

Great that you got it installed....hope it was not too much of a pain!

It seems that the boost pressure seems to be more related to engine load than to engine rpms. For example if I am going downhill on the highway and have 2800rpm on the tach the boost pressure is generally in the 5psi range or lower depending on how downhill it is. Compared to if I am going up hill on the highway and the tach is reading 2800rpm the boost gauge is generally reading around max boost, around 11psi in my case.

A couple of warnings.

1. 15psi is too high unless you have a pyro gauge measuring your exhaust temperatures. The manual says 10-12psi. I went with 11psi to be safe. You really don't want to cook the engine.

2. Make sure that your hose is not leaking. If you had to couple the hose then there is a possiblity that there is a small pressure leak and that might make the gauge read lower than the actual boost pressure. I am not sure if a leak in the hose would cause an overall boost pressure drop or not, but if the pressure is higher than your gauge is reading then you could end up frying your engine. I made a short hose and attached it right at the injection pump to verify that I was getting the same readings with the short hose as I was with the long coupled hose.


Hope this helps.

-Mark

[EricN]

I assume you are actually hearing the blow off valve (quite audible when it blows and you can feel it)? Mine used to come in around 16 psi but since I have been bouncing off of it alot it seems to be getting weaker, down to 14psi. I would first confirm that your gauge isnt faulty. If the gauge is ok, then you will need to replace the valve or take it apart and get creative and try shimming the spring or something. I dont know if it is possible to adjust it but one day soon I will be taking mine apart and checking.

[visotzky]

Actually it was easy, since you did all the thinking! anyway would the boost pressure drop if one of the vacuum hoses leaked? The guage would read low but would that affect actual turbo boost? any one. Yes I hear a pssst pssst sound and the gauge stumbles. it's possibly a leak as i had a bugger of a time getting the T into the old hose, I see tommorrow if it's on right. What's an easy way to check the gauge?
Cheers

[EricN]

After you check for the leaks, if it is still reading low, the only way to test the gauge is try a different gauge.

[coaxial]

on a stock engine without any modifications should one be able to hear a blowoff valve? I have never noticed such a thing.. would it require quite high revs? I would expect it to be quieter than the valves on riced out civics and whatnot but I haven't heard anything at all out of mine.

[EricN]

Unless you have a problem, (or you have adjusted for too much boost) you should never hear the valve blow off.

[DelicaMark]

Hey coaxial I am glad someone asked about the blow off. I have never heard mine either. Sounds like that is okay...glad I don't have to worry about that!

-Mark

[robinimpey]

Okay, now you guys have got me all excited about getting a little more juice out of my van.

A couple of questions/comments.

Have any of you who have adjusted your linkage found that you not only got more power, but also changed your fuel economy? Better/Worse?

Do we know if 15 psi is the factory set for the blow off?

Does anyone know how hot is too hot for exhaust gas temperature? I'm talking post turbo.

I have been doing some research and it seems like the best way to alter/control the boost is to add a boost controller to make sure a person is maintaining just the boost pressure you want. Also it seems like some good insurance to add a boost gauge and EGT(pyro) gauge. I have found a couple of places that have dual boost/EGT gauges that should look decent. Lastly oversizing exhaust would also be a nice little addition as well.

If anyone has any further thoughts/insight I would be happy to hear it. I'm beginning to feel a bit like a kid in a candy shop. Much like I did when I first started toying with the idea of buying a Delica.

[EricN]

I never noticed any change at all in fuel economy but I didnt have the van long enough to really scrutinize before boosting it. Max EGT post turbo is on here somewhere. I think someone mentioned 300f less if you measure post turbo and as far as I have been able to find out, 1200 f is the absolute max you ever want to hit, so 1100 f to be safe, in the case of post turbo that would mean 800 f.

[robinimpey]

Thanks Eric,

I think I'm going to order some goodies for my van and I'll let you all know how my modifications turn out. I'll try and calculate just how much everything changes from before putting on a boost controller and larger exhaust to after.

[visotzky]

OK my problem was a leaky hose, all seems good now, but mine seems to be more sensitive to adjustment than the 4 turns described. More like a 1/2 turn per psi, which would explain the over adjustment. I got it maxing out at about 11 at the moment and there is no blow off.
Cheers

[BCDelica]

Happy New year Eric, did you complete your pyro install and how are your temps? I won't consider adding a boost gauge with out a pyro gauge, where did you mount your sensor?

Questions, so many questions!!

[robinimpey]

I'm going to mount my sensor as close to the turbo as possible, but not before. More accurate temp reading if before the turbo, but I've heard of sensor parts coming off an taking out the turbo.

[EricN]

Happy New year Eric, did you complete your pyro install and how are your temps? I won't consider adding a boost gauge with out a pyro gauge, where did you mount your sensor?

Questions, so many questions!!

I started a new job (back friendly) so time is a bit short. I have the pyro in but only have the sensor strapped on to the outside of the manifold (mostly to keep it safe), The maximum temp I have seen with this setup after climbing up Mt. Seymour with a trailer full of bikes and a truck load of riders (so full throttle, doing 45km/hr) was just under 600F. Hoping the weather will warm up and allow me to pull the turbo out but looking at it the other day, I think I may need to pull the turbo off with the exhaust manifold. The bolts holding the turbo to the manifold look a bit interesting to access otherwise.