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Sam Handwich
03-06-2010, 12:31 PM
Could anybody please tell me the limit at which my standard turbos can run at please? I'm having a boost controller fitted today and knowing this would be usefull :P

miller
03-06-2010, 12:33 PM
without Intercooler your probably in the region of 14psi before fuel cut happens. With intercooler this figure will drop to around 9psi before fuel cut.

all dependant on each individual car though, whoever is fitting it should be testing each increment etc

elnevio
03-06-2010, 12:52 PM
Indeed it is dependent on the car in question. With intercooler, I can get 14psi without fuel cut. /woot2

miller
03-06-2010, 01:06 PM
Indeed it is dependent on the car in question. With intercooler, I can get 14psi without fuel cut. /woot2

fuel pump helped?

elnevio
03-06-2010, 01:24 PM
fuel pump helped?
It certainly restored the position (i.e no more cutting out under heavy load).

martin_y
03-06-2010, 01:58 PM
without Intercooler your probably in the region of 14psi before fuel cut happens. With intercooler this figure will drop to around 9psi before fuel cut.

all dependant on each individual car though, whoever is fitting it should be testing each increment etc

isnt this the wrong way round?

Atik
03-06-2010, 02:04 PM
Nope Martin, it is the right way round. Beats me why though!?!

mike74
03-06-2010, 02:08 PM
cold air is denser so means more fuel to suit...i think?

miller
03-06-2010, 02:12 PM
cold air is denser so means more fuel to suit...i think?

Yes but stock fuel delivery cant cope hence fuel cut.

So similarly getting same power with intercooler as without BUT working the turbos waaay less to acheive it if that makes sense?

Ghost_2008
03-06-2010, 02:20 PM
When you introduce an after market intercooler, the new cooler is (should be) less restrictive, so you are flowing the same amount of air but at a lower pressure....... Fuel cut happens when the fuel to air ratio become "Air" heavy and the fuel detenates before the spark is introduced, also known as a knock event....... Fuel cut is part of the ECU programme designed to protect the engine..........

So as miller has said above, the turbo's are work more efficiently and are under less strain......... in theory should last longer..........

Nick Mann
03-06-2010, 02:52 PM
Not quite. Uprated intercoolers should cool the air more - colder air = denser air, so more flow for the same pressure, or lower pressure for the same flow.

Fuel cut happens because the car sees too much air flow for a certain part of the fuelling table. I *think* the ecu looks at TPS and revs maybe more and then works out the fuelling based on the air flow. If the ecu sees so much air flow it is worried about providing enough fuel, then it cuts fuel rather than run lean.

So increasing your fuel delivery system should in theory not have any significant effect on fuel cut unless you also modify the air flow signal downwards to suit the extra fuel capabilities.

Everyone is right about turbos working less hard with an uprated intercooler though!

Sam Handwich
03-06-2010, 03:51 PM
Well i'm not running an intercooler so i take it 13psi should be safe?

martin_y
03-06-2010, 09:21 PM
Thanks all, that makes sense now. Fuel cut is caused by too lean a mixture in this case.

So, theres no point in upgrading the intercooler without some other mods, right?

Sam Handwich
03-06-2010, 11:32 PM
Well i've had the boost controller fitted, trouble is when i run more boost i can hear a sort of ticking/clicking sound behind my dash :/ anybody know what this might be?

Nutter_John
04-06-2010, 12:09 AM
yeah thats your boost solenoid working :)

Turbo_Steve
04-06-2010, 12:11 AM
Where is your boost control solenoid mounted? Chances are you can hear it cycling through your bulkhead.

If you're going for 13psi, I hope whoever installed it ran the car with a Wideband on to ensure your AFRs are safe.


Martin, Fuel cut has nothing to do with the fuel mixture. End or story.
The ECU looks at the amount of air being drawn by the engine, and if it's more than a specific mass (for a given set of parameters, load, TPS, RPMS whatever) it simply goes "NOPE" and stops fuelling to prevent any more boost.

There is little or no point in doing most mods to a VR4 without an ECU to support them. Once you've turned the boost up and freed up the exhaust system, you're only getting very marginal gains for your expenditure: the ECU is the next limitation as it actively stops you making more power. You can then fit a bigger intercooler to try and wring a bit more out of the turbos, but really, once you've remapped, you've got all you're going to get out of them wihtout upgrading to bigger ones.


I would also like to point out that there is an ENTIRE FORUM dedicated to boost control, and you've posted this in UK Chat!!?? I'm going to move it.

John TheAntique
04-06-2010, 12:24 AM
That's normal, it's the solenoid unit which is proably mounted on the bulkhead. If you don't like it move it further away.

Sam Handwich
04-06-2010, 01:38 AM
Thankyou all. And sorry Turbo Steve...

GroundControl
04-06-2010, 03:10 AM
I've got an EBC but am not running an uprated intercooler or exhaust. With my current settings I seem to be peaking around mid 14 then settling in the 13 PSI range, that seems to be just on the verge of fuel cut for me (although after the trackday on Monday my EBC is now showing a peak recorded value of 15.6 PSI).

Have had it on the dyno with those settings and the AFRs were OK then.

We're coming into winter here and the temps are dropping so I'll probably have to drop the boost settings back a notch for winter.

Sam Handwich
10-06-2010, 07:16 PM
I think i may have blown a turbo :/

bradc
10-06-2010, 08:00 PM
Why do you think that?

steelie600
10-06-2010, 08:04 PM
Well i'm not running an intercooler so i take it 13psi should be safe?
Yes you are its a big black thing behind the bumper

Turbo_Steve
10-06-2010, 10:06 PM
its a big black thing behind

/JawDroppi


the bumper

:whistle:

Thank goodness for that - you had me worried there.

And entirely accurate!

bradc
11-06-2010, 10:02 PM
There is little or no point in doing most mods to a VR4 without an ECU to support them. Once you've turned the boost up and freed up the exhaust system, you're only getting very marginal gains for your expenditure: the ECU is the next limitation as it actively stops you making more power. You can then fit a bigger intercooler to try and wring a bit more out of the turbos, but really, once you've remapped, you've got all you're going to get out of them wihtout upgrading to bigger ones.


I have to disagree with this. In NZ the standard power figure at the wheels on a VR-4 is around 160kw for a manual. At the last dyno day we had the cars with exhaust, boost and intercooler were running around 180-190kw at the wheels. I think that 20-30kw at the wheels which is around 25 to 37kw or so more at the engine is actually a very very good gain for such simple mods. It is also worth pointing out that one car in particular which was an auto. On the same day a 100% stock PFL auto made 140kw, this other car made 167kw which isn't bad for a PFL auto. It had the same exhaust + boost + intercooler. 27kw at the wheels is very impressive for such basic mods.

Furthermore in that very same car I went down to Levin in it and we averaged bang on 10l/100km which is 28.3mpg or there abouts over 1100km of driving.

Ryan
11-06-2010, 10:16 PM
That's right Brad. Also, if these mods did not yield any performance gains, why would people continue doing them? The majority of people on this thread who have modified their VR-4's have not modified their ECU in any way/shape / form and yet see significant performance gains:

* Myself
* William
* Kenneth
* wintertide
* GroundControl

etc etc etc

AlanDITD
11-06-2010, 10:16 PM
I have to disagree with this. In NZ the standard power figure at the wheels on a VR-4 is around 160kw for a manual. At the last dyno day we had the cars with exhaust, boost and intercooler were running around 180-190kw at the wheels. I think that 20-30kw at the wheels which is around 25 to 37kw or so more at the engine is actually a very very good gain for such simple mods. It is also worth pointing out that one car in particular which was an auto. On the same day a 100% stock PFL auto made 140kw, this other car made 167kw which isn't bad for a PFL auto. It had the same exhaust + boost + intercooler. 27kw at the wheels is very impressive for such basic mods.

Furthermore in that very same car I went down to Levin in it and we averaged bang on 10l/100km which is 28.3mpg or there abouts over 1100km of driving.

Yeah to be fair i would agree, Roughly speaking your talking about knocking 1second off your 1/4mile time with upped boost and a full exhaust with downpipes. Maybe more with intercooler hard pipes etc....then a remap possibly a touch more....dare i say 12's.....without nitrous..i would hope so.

1second isnt to be sniffed at thats a hell of a difference.

bradc
11-06-2010, 10:23 PM
Unsure about 1/4 times Alan as not many of us have run quarter miles down here. But yes there is a massive power gain to be given by doing those three mods.

AlanDITD
11-06-2010, 10:28 PM
Unsure about 1/4 times Alan as not many of us have run quarter miles down here. But yes there is a massive power gain to be given by doing those three mods.

Dude when i get the **** out of london im going to buy a manual galant VR4 and it will run a 12s 1/4 mile no nitrous!

Turbo_Steve
12-06-2010, 01:05 AM
Let me rephrase, as you've all got the wrong end of the stick: I can see why what I have written may be misinterpreted:


here is little or no point in doing most mods to a VR4 without an ECU to support them. After you've turned the boost up and freed up the exhaust system, you're only going to get very marginal gains for your expenditure: the ECU is the next limitation as it actively stops you making more power. You can then fit a bigger intercooler to try and wring a bit more out of the turbos, but really, once you've remapped, you've got all you're going to get out of them wihtout upgrading to bigger ones.

Once you've put an exhaust on it and boost (theyre's your 1 second, Alan) the next thing you fit is probably the intercooler....and have to turn the boost down to avoid fuel cut. Every additional breathing mod you do brings the boost pressure down and down trying to avoid fuel cut: the turbos are flowing the same. They may be running a bit cooler.....but then the ECU isn't adjusting the fuelling or the ignition in response to it, so you're not gaining much at all, at least not against what you're spending out.

bradc
12-06-2010, 01:07 AM
I disagree, the difference between 160kw and 180-190kw is pretty big.

We've had cars in NZ making around 175kw with 12psi and stock exhaust, so the remaining 5-15kw will be due to the intercooler and exhaust. The intercooler may not help a single run but it will keep the car in the best fuel map for much longer periods of time before the ecu pulls timing and dumps in fuel.

These same cars are going from 363nm of torque to anywhere from 420nm to 450nm which is a massive gain as well. Overall the area under the curve is greatly, vastly in fact increased.

bradc
12-06-2010, 01:08 AM
Your second reply makes a bit more sense.

I agree, after boost, exhaust and intercooler there isn't much to be done to increase the power out of a VR-4 with stock ecu and turbos

Turbo_Steve
12-06-2010, 01:09 AM
But you're changing the exhaust both times?
If you took a standard car and fitted an intercooler, and saw an extra 15Kw then I'd say fair enough.....but the exhaust makes a HUGE difference.

I've yet to get my intercooler warm at 12psi, because the car is moving quickly enough to cool it.

bradc
12-06-2010, 01:15 AM
Thats true, a completely stock car won't see much gain from changing the intercooler because the stock one is capable of handling the heat.

But with increased boost the cars do knock quite a bit with the stock intercooler. Dickytim over here was running 14psi or so and after he installed an aftermarket intercooler found that his fuel economy was improved quite a bit and evoscan showed that it was spending most of it's time at 100 octane level, rather than dropping down to low 90's with the stock intercooler.

SquattingDog
02-07-2010, 08:04 AM
Fuel cut has nothing to do with the fuel mixture. End or story.
The ECU looks at the amount of air being drawn by the engine, and if it's more than a specific mass (for a given set of parameters, load, TPS, RPMS whatever) it simply goes "NOPE" and stops fuelling to prevent any more boost.

Sorry to play the Necromancer here, but I just wanted to chime in on this (have been a little afk recently).

Correct me if I am wrong, but the ECU does not look at how much air, or mass of air before determining whether to cut the fuel, but more specifically the set load values at each RPM.

People keep saying it's to do with injectors and/or fuel pump - this is absolutely not correct (as stated above by Turbo_Steve). You could upgrade to a Walbro or better with 1000cc injectors and still "boost cut" (this is fuel, not boost cutting off) at the same boost level, simply because you are causing X load on the engine.

It would, however, be possible to run maybe 1 - 2psi more (maximum) with these upgrades, if indeed there was an issue with air/fuel running too lean and thus creating additional load on the engine. In my experience, this is not usually the case.

The colder the air being drawn in (eg the bigger the intercooler, and the better the flow from front-to-back of it; or with meth injection) - the lower the pressure of boost for the same amount of required fuel, as cold air is denser and lets the engine breathe better. This is why we fit intercoolers/meth to our cars. So yes, you should get the same performance at lower boost with a bigger intercooler (to an extent).

Further discussion welcome - I'm always learning too :)

bradc
02-07-2010, 09:09 AM
Basically, yep!