R33 Boost Build Up

[Levi_]

Ok, I had a quick search but I'm having a hard time finding much useful information, so sorry if this has been asked before, but if it has, feel like linking me to help me out?

Ok, I've got a '96 R33 GTS25t Manual with the following mods; (i've only listed those relevant to the question)

• FMIC 600x300x76
  
• Pod Filter
  
• Split Front/Dump
  
• Decat Pipe
  
• Full 3" Cat-back
  
• Manual Boost Controller
  
• S-AFC Neo Piggyback ECU
  

Stock turbo.

So, what I understand is because of my mods, I've pushed my minimum boost pressure up, previously with the boost controller wide open (or having my bleed connected directly to the wastegate) I was hitting about ~8psi of boost (my turbo timer has a digital boost gauge). Now the lowest peak boost I can get is about 10psi (with the occasional spike to 11/12ish). Now I'm alright with this, but after getting my car tuned I noticed my boost curve is pretty crap, I'm not worried about it trailing off as much as full boost not hitting until ~5200rpm.

I've posted my dyno graph with boost shown (the current boost is the line that is lower at 6500rpm) but incase you can't read it here's the breakdown:

3000rpm - 6.5psi

4000rpm - 7.5psi

4500rpm - 8psi

5000rpm - 9.5psi (suddenly ramps up here)

5250rpm - 10psi

5500rpm - 10psi

6000rpm - 9psi (sits about there maybe a little lower until redline)

Now I'm not sure, but I thought the boost shourl really ramp up earlier than that. The problem is that it's quite noticable, once my car hits ~5000rpm the whole car roars up and pulls like crazy, but it'd be nice to have a bit more of that down lower. So, essentially what I'm asking is;

1) Should the boost be higher at a lower rpm?

2) If so, should I look at a electronic boost controller or is it caused by my wastegate or soemthing else all together?

[W0rp3D]

i dont see the graph?

Maybe it is something in the tune, .5 psi at the top end would not pull any harder, i use to feel this when i was using the avcr, up until around 4k it would only go to 8 or 9psi then shoot up to 14, now that i just use an adjustable wastegate its smooth push from 3-3.5k to full boost by about 4.5k.

[Levi_]

Try this link: http://levibuzolic.com/files/Image013.jpg

It's more the difference between ~4600 (8psi) to 5200 (10psi). If you see the graph it's climbing steadily and then all of a sudden it really starts to jump up and hits full boost, from then on the car pulls really hard, but before that it's all reasonably calm.

[Abo Bob]

Are you sure your boost controller is hooked up right? The curve looks how I would imagine it would look with those mods if you had no boost controller connected at all.

[DECIM8]

Increase the length of the hose connecting to the actuator.. about 2 meters at max.. This will get boost up quick..

It may spike but if thats what you want it will work

Edited August 4, 2008 by DECIM8

[MBS206]

Increase the length of the hose connecting to the actuator.. about 2 meters at max.. This will get boost up quick..

It may spike but if thats what you want it will work

An idiotic idea, and a brilliant way to kill a turbo from major spiking...

What boost controller do you have on there?

That really is a slow curve, and is NOT right.

Have you looked at getting the $30 ebay turbo tech one? They work brilliantly.

And a stock turbo, with those mods, should be seeing 10PSi by no later then 3000RPM.

[Levi_]

I had a basic manual one but replaced it with the tubotech item when I did my FMIC.

Essentially I have the turbotech item turned all the way in (I think) which is 100% open (I know I have it 100%, just can't remember if the turbotech is all the way in or out, because my old one was the opposite). Which means at the moment it's no different to having my wastegate hooked up directly.

Will turning the boost controller up to a certain point bring the boost up to ~10psi earlier without exceeding it? I'm a little worried about spikes, because I can't afford a new turbo, but if I can squeeze some more mid-range out of this one, I'd be really happy.

I'll have a play with it tonight, but thanks for confirming my suspicions that the curve isn't right, I was sure the stock turbo should spool up much faster than it currently does.

[DECIM8]

If everything is setup correctly then you wont have an issue if boost is bled off at the right amount you will be fine..

http://autospeed.com/cms/A_1053/article.html

Edited August 4, 2008 by DECIM8

[Birnie]

You have bypassed your original boost solenoid all together right?

That's not needed at all once a bleeder is installed (just checking that for starters)

And also checking that cause it almost looks like you still have a 2 stage boost happenning at the 4500-5000 mark.....the normal place to change from 5-7psi.

Also, if your bleeder was at 100% open, you'd be hitting well over 14psi with a huge spike.

I've done it when mine wasn't installed right ont the standard turbo.

Start screwing the oposite direction a few turns at a time to see what happens.

From my first glance, looks like it's installed in between the solenoid and wastegate, and completely shut which would still probably screw with the boost levels/flow a bit.

[Levi_]

Ok I've got some progress!

I realised I did have the controller hooked up incorrectly because I have a in-cabin controller and they need to be hooked up differently to the boost-T. I had the in-cabin controller hooked up like a boost T which meant that the air had nowhere to go and would just end up flowing to the wastegate.

I've now hooked it up as shown in this image:

But it was still overboosting. So I removed the T restrictor (there is a spring and ball bearing inside the T that helps control the air distribution between the wastegate and the controller). Once this was removed and the controller turned all the way down as closed as it would go. We achieved the lowest boost setting I've seen in months! The boost comes on fast and hits 8psi and then just locks itself there.

I pulled over and turned the controller up by half a turn and I managed to get it to hit 10psi by 3000rpm! Unfortunately it seems to still climb up to ~13psi under heavy load in higher gears, so I've turned it back down to about so it's at about 1/2 turn from completely closed, so I'll give that a bit of a run on the way to work in the morning and see how I go.

Looks like I'm going to need another tune. WHich is good, because I wasn't 100% satisfied with what I currently had.

PS: Oh and yes, the standard solenoid is long gone, got rid of that within a few weeks of getting my car.

[R31Nismoid]

If everything is setup correctly then you wont have an issue if boost is bled off at the right amount you will be fine..

http://autospeed.com/cms/A_1053/article.html

lol @ backyard mods like that and no surprise its on a VL at all.

The longer the hose etc the worse the spike potentially is gonna be.

Get a decent EBC and it'll do the same thing, reliably and safely every single time as good as running no gate.

[W0rp3D]

lol @ backyard mods like that and no surprise its on a VL at all.

The longer the hose etc the worse the spike potentially is gonna be.

Get a decent EBC and it'll do the same thing, reliably and safely every single time as good as running no gate.

that article was also written 7 years ago, a lot has changed in those 7 years.

I have a good ebc (avcr) and it does not stop waste gate creep, the only thing that will stop that is a good external gate with good flow capacity, unlike an internal gate.

[DECIM8]

I think the point he was making is that he cant afford one.. thats why I suggested it..

[Levi_]

I'm still having a hard time keeping boost level. I can get it to hit 9/10psi before 3000rpm which is great, but it still tends to peak up to ~11/12psi when the revs hit ~5000rpm.

I don't really have the money for an electronic boost controller, but if that's what it will take to get a more reliable boost pressure then I'll have to look into it.

Can anybody recommend a good, simple electronic boost controller?

[W0rp3D]

I'm still having a hard time keeping boost level. I can get it to hit 9/10psi before 3000rpm which is great, but it still tends to peak up to ~11/12psi when the revs hit ~5000rpm.

I don't really have the money for an electronic boost controller, but if that's what it will take to get a more reliable boost pressure then I'll have to look into it.

Can anybody recommend a good, simple electronic boost controller?

I have $400 ebc and i still get boost flare, its not a boost controller problem its an internal gate problem, 1-2 psi is not much when its coming onto boost fast, and 12psi is still safe for your turbo, untill you get an external gate then thats just the way it will be.

[Munkyb0y]

$30. holds your chosen boost level all the way to redline.

Edited August 5, 2008 by Munkyb0y

[Levi_]

$30. holds boost all the way to redline.

Had one of those, upgraded to the kit I have now as I wasn't entirely happy with that one.

I guess I'll take my car for another drive this afternoon and see how I go with setting the boost. I must look strange pulling over every 30 seconds to open my bonnet.

[Munkyb0y]

2 questions

do you still have the factory hose with restrictor in place feeding pressure to the boost controller?

does ur turbotech have a small hole drilled into the side (opposite the actuator nipple)

[Levi_]

2 questions

do you still have the factory hose with restrictor in place feeding pressure to the boost controller?

does ur turbotech have a small hole drilled into the side (opposite the actuator nipple)

Restrictor is gone, it's all clear and open silicon hosing.

And no, it deosn't because it's an in-cabin controller, not a boost-tee like I originally thought.

[Munkyb0y]

ok

i was talking about the turbotech, not the 2 stage.

the turbotech suffers from lag on gear changes if there's no hole in it. but i doubt that would be an issue on the dyno.