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orionn2o
01-08-2006, 07:12 PM
Does anyone know what the safest highest boost, the VR$ can handle with a relatively stock engine??? And also what are the limiting factors???

Nutter_John
01-08-2006, 07:21 PM
Hi there

I think upto 1 bar is safe above that you get fuel cut etc , try searching for boost controllers on here loads and loads of info

BraindG
01-08-2006, 07:25 PM
1bar is safe (i run at that day in day out), aslong as you got a fairly decent controller that wont spike to much.. engines have been know to pop heading into 1.3bar..

orionn2o
01-08-2006, 07:38 PM
Ok cos mine boost controller has a hi mode of 11.5 psi and i have a walbro fuel pump.


The boost seems very stable at the mo, so you reckon i could turn up to say 13/14 psi without issues???

Nutter_John
01-08-2006, 07:39 PM
14.7 psi is 1 bar - i run mine at 0.9 bar with no issues

this is not a recomendation though :)

Axeboy
01-08-2006, 08:10 PM
I used to run at 0.85 bar as a safe high and the car felt great.

However, 1 bar maybe more will be minimum as from monday on my current vr4... wo0000000000000

colVR4
01-08-2006, 09:36 PM
I run at 15 psi with the Apexi S-AFC fuel computer. Never had fuel cut yet and no issues with turbos feeling like they are out of puff.

White Lightning
01-08-2006, 09:46 PM
Apologies for hijacking the thread but this is related question :party3:

If each turbo supplies each back of 3 cylinders, where does the boost gauge read the boost pressure? Does it just read the boost pressure from one turbo or is the boost combined somewhere in the inlet manifold ???

The Vee
01-08-2006, 09:56 PM
Apologies for hijacking the thread but this is related question :party3:

If each turbo supplies each back of 3 cylinders, where does the boost gauge read the boost pressure? Does it just read the boost pressure from one turbo or is the boost combined somewhere in the inlet manifold ???

3 cylinders supply each turbo and they both combine to produce the boost which is normally measured in the inlet manifold (via piping) . The manifold uses the combined boost to supply all six

White Lightning
01-08-2006, 09:59 PM
Ahh, right, doh!

So let's just see if I've got this right.. each turbo runs off one bank of 3 cylinders and they both supply the boost pressure in the inlet manifold. So, the boost gauge is measuring the combined boost pressure of both turbos and therefore if one turbo was not running right you would not get the correct boost pressure - is that right?

Kieran
01-08-2006, 10:30 PM
Yep - when a turbo pops, as Nick and Derek will tell you, the other can't keep up and you see little if any boost at all!

Wodjno
01-08-2006, 10:47 PM
I run at 15 psi with the Apexi S-AFC fuel computer. Never had fuel cut yet and no issues with turbos feeling like they are out of puff.

And you hold 15 psi to the redline ??

Sports GT
02-08-2006, 05:22 AM
I have a problem, experiencing a cut at 14 PSI and I'm not sure what it is... the car begins to stutter at 1 bar. I have a GReddy Profec EBC and we connected the vacuum lines correctly but it doesn't seem to be working.. the Fuzzy Logic mode doesn't pick up the boost curve and when trying to control it via the knob, it spikes no matter what it is set to... What causes boost spike? and what cut am I experiencing?

BraindG
02-08-2006, 09:02 AM
What causes boost spike?
Here (http://www.clubvr4.com/forum/showthread.php?t=10087) is a great write up by BDA explaining all about boost spikes

White Lightning
02-08-2006, 09:19 AM
Yep - when a turbo pops, as Nick and Derek will tell you, the other can't keep up and you see little if any boost at all!


Cheers Kieran :2thumbsup

I'll stop hijacking the thread now :evilgrin:

Axeboy
02-08-2006, 09:26 AM
I run at 15 psi with the Apexi S-AFC fuel computer. Never had fuel cut yet and no issues with turbos feeling like they are out of puff.

Col, can you let me know more about the safc settings you use at 1 bar...

Sports GT
02-08-2006, 02:57 PM
Here (http://www.clubvr4.com/forum/showthread.php?t=10087) is a great write up by BDA explaining all about boost spikes



Can't access it due to lack of CVR4 membership

colVR4
02-08-2006, 06:26 PM
On the advise of a local garage (I haven't had it properly set up so take these with a pinch of salt) I have got the following:

Hi-Lo Throttle point: 25% 70%
RPM settings at: 2000 2500 3000 3500 4000 5000 6000 7000
Hi Settings: -1 -2 -2 -2 -2 -2 -2 -2
Lo Settings: -4 -6 -8 -10 -10 -10 -10 -10

I did a quick blast with WOT and the AFR (garage let me borrow it for free with technician sat beside me checking the readings) was still showing well in the safe region throughout the rev range with these settings at 1 bar.

The technician definately advises getting it set up properly but he reckons that the fuelling could be reduced by anything up to 25% at certain rpms and throttle positions!!

Wodjno
02-08-2006, 09:56 PM
So are you holding 1 bar to 7000rpm ??

And if you require a Wideband Lambda Sensor with Logging and Analysing capabilities ?? I can supply one to you at a cost of £30 per week ! Any breakages paid for by yourself.. !

colVR4
03-08-2006, 06:44 PM
Seeing no loss of boost at all, all the way through to redline :D

Axeboy
03-08-2006, 07:37 PM
I'll try those settings tomorrow... :)

Then ill have it tuned properly, when i get time

Wodjno
04-08-2006, 09:12 AM
Seeing no loss of boost at all, all the way through to redline :D

Well your car must be the first VR4 ever to achieve that :speechles Well done :2thumbsup

dickytim
05-08-2006, 11:50 PM
my Kenny-made boost tap works perfectly, holds 13.5-14psi upto 6,000rpm but we dont really need to rev our cars to 7,500rpm for peak power any way which is obviously a good thing, I would rather peak power and boost at 5,500-6,000 and save my engine just that little bit.

agilroy
06-08-2006, 11:39 AM
my Kenny-made boost tap works perfectly, holds 13.5-14psi upto 6,000rpm

What does this boost tap look like?? Any info? I have an electronic but the thing is to old and the boost is all over the place.

dickytim
07-08-2006, 09:01 AM
sorry no pics it look like a plumbing t-piece and a screw with a spring and a small ball bearing inside it.

Kenneth
08-08-2006, 02:13 AM
haha, made that with the help of my step-father out of old brass hose connectors :) cost me $0

colVR4
08-08-2006, 04:34 PM
Well, I am not seeing any noticealbe drop-off of boost but I need to get it on a rolling road to confirm it.

agilroy
08-08-2006, 10:05 PM
sorry no pics it look like a plumbing t-piece and a screw with a spring and a small ball bearing inside it.

Choice, so its basically a gated boost controller... Im thinking about
getting my hands on one of those to try. My electronic is useless