Feck me! (Unexpected BPU)

Just overtook someone when driving home, put my foot down and feeeeeck, car took off like a rocket! Checked the boost gauge and I'm now running 1.35bar..

I think someone put a different restrictor ring in when changing my exhaust, and 'forgot' to tell me..

It feels like a completely different car.

I'm still of the opinion that restrictor rings don't work properly. I had one on one of my old cars and it regularly boosted to much more than the ring was supposed to have allowed.

just cold air and you havent used the car much lately due to the weather?

so it raised the boost and surprised you

Just overtook someone when driving home, put my foot down and feeeeeck, car took off like a rocket! Checked the boost gauge and I'm now running 1.35bar..

 

I think someone put a different restrictor ring in when changing my exhaust, and 'forgot' to tell me..

 

It feels like a completely different car.

I be t it was fun but I would look aty the 1.35 bar from a reliability aspect as I think that usual BPU mods are only suitable for about 1.2bar.

I be t it was fun but I would look aty the 1.35 bar from a reliability aspect as I think that usual BPU mods are only suitable for about 1.2bar.

unless your elite

I be t it was fun but I would look aty the 1.35 bar from a reliability aspect as I think that usual BPU mods are only suitable for about 1.2bar.

Yeah I didn't put my foot down afterwards, I was tempted to though. (Self destructing jspecs would be a reason to go Single..)

Do you realise that ambient temperature has an effect on what boost you'll see. With mine set via the boost controller to 1.1 bar in the summer, the same setting will see 1.25 on a cold winter day.

The other aspect is, that it's not just the RR that has a say on what exhaust gas restriction is like. The exhaust itself will have an effect. So changing your exhaust will probably change your boost output too.

Hence why no two supras seem to boost the same with similar mods. There are a lot a varying factors that need to be considered.

If you find you're suddenly boosting to 1.35 after a new exhaust has been fitted, I'd check to see they've fitted the ring at all.

i found this out last night, i have a restrictor ring on mine and it hit 1.2 bar last night, normaly about 1 bar

Do you realise that ambient temperature has an effect on what boost you'll see. With mine set via the boost controller to 1.1 bar in the summer, the same setting will see 1.25 on a cold winter day.

Does the boost controller not compensate for that to keep the boost at whatever you've set it to? I admit I'm a bit new to this turbo malarky, I was too busy grinning to remember 1.2bar was the safe limit for jspecs (but the little red light coming up on the boost gauge made me think twice).

I cannot wait to go BPU , would be a good experience in a tunnel, roof off and bpu .

I've said it before, I'll say it again - I can't even imagine what a single is like!

Do you realise that ambient temperature has an effect on what boost you'll see. With mine set via the boost controller to 1.1 bar in the summer, the same setting will see 1.25 on a cold winter day.

Why is this? I read this all the time but it makes absolutely no sense from a physics point of view. My car doesn't make any more boost in the winter and all I have is a restrictor ring... no boost controller.

My reason for thinking this....

The temperature doesn't have any direct bearing on the pressure seen at the manifold, well I cant' see why it would anyway. Boost controller works by tricking the actuator on the wastegate into thinking that there is less boost than there actually is. Stock boost of 0.7bar actuates the wastegate and controls the boost at this setting. The boost controller simply interupts this pressure and tricks the actuator, when the manifold reaches 1.2bar the boost controller (electronic) doesn't let the actuator see any boost until the manifold reaches 1.2bar and then it opens and closes to control the flow of boost (might not be accurate but that is how I understand it).

Now.... its very very cold. The pressure in the manifold is 1.2bar... what happens? The boost controller allows the wastegate to open and controls the boost at 1.2bar. Why would the temperature change that? What DOES happen in lower temps is the density of the charge changes... giving more oxygen to which more fuel can be added giving more power.

I'm not saying that in some or maybe even most cars there is a difference in the winter. I just can't see why it would make a difference, and it doesn't on mine

Colder air is more dense, hence contains more oxygen which gets into the cylinder, so creates a bigger bang. HTH

Yup as has been mentioned.

Pressure is controlled by the wastegate.

Volume is controlled by virtue of the fact the displacement of the engine is fixed.

Density is controlled by ambient temperature and charge cooling.

Increase any of those three and with correct fuelling and ignition timing you'll see an increase in power.

Simples

Colder air is more dense, hence contains more oxygen which gets into the cylinder, so creates a bigger bang. HTH

Yup as has been mentioned.

Pressure is controlled by the wastegate.

Volume is controlled by virtue of the fact the displacement of the engine is fixed.

Density is controlled by ambient temperature and charge cooling.

 

Increase any of those three and with correct fuelling and ignition timing you'll see an increase in power.

 

Simples

Increase in power... yes. But where does the increase in boost come from? I'm a logical guy at heart so I like to understand things before I accept them. People always bang on about the boost increases in the winter but I can't fathom why.

As yourself and Gaz have said.... that is exactly how I understand it.

I cannot wait to go BPU , would be a good experience in a tunnel, roof off and bpu .

 

I've said it before, I'll say it again - I can't even imagine what a single is like!

I went in a single once......................phenominal:d

Sorry to hijack a thread but since its sort of the topic anyway- I have a single decat (second cat at the rear is still in the car) with a 3" exhaust and mine only boosts to .9 bar- does this mean I have a restrictor ring in it or is it just the second cat doing the restriction ?

I went in a single once......................phenominal:d

I was very much impressed when I returned from Enfield in 2007 after Paul and Darren BPU'd my Supra (1.4bar on euro-spec tubbies). There was a big difference compared to the stock setup.

A year later, during my trip home from Enfield after the single conversion, I slowly drove to the continent (leaving Whifbitz at 02 o'clock in the morning, I was more than occupied driving on the other side of the road in the dark ). On French ground (exiting the Eurotunnel), I was in 3rd gear when joining the mainroad ... and I floored it (PHR @1.6 bar) ... I was so suprised (and probably frightened too) that I forgot which gear would come next

I was very much impressed when I returned from Enfield in 2007 after Paul and Darren BPU'd my Supra (1.4bar on euro-spec tubbies). There was a big difference compared to the stock setup.

A year later, during my trip home from Enfield after the single conversion, I slowly drove to the continent (leaving Whifbitz at 02 o'clock in the morning, I was more than occupied driving on the other side of the road in the dark ). On French ground (exiting the Eurotunnel), I was in 3rd gear when joining the mainroad ... and I floored it (PHR @1.6 bar) ... I was so suprised (and probably frightened too) that I forgot which gear would come next

it should be 4th gear mate, it's right under 3rd gear...

Increase in power... yes. But where does the increase in boost come from? I'm a logical guy at heart so I like to understand things before I accept them. People always bang on about the boost increases in the winter but I can't fathom why.

 

As yourself and Gaz have said.... that is exactly how I understand it.

Ah OK, no probs.

It's because boost controllers and gauges, tend to use gauge pressure rather than absolute, so they don't take into account changes to ambient.

Ah OK, no probs.

It's because boost controllers and gauges, tend to use gauge pressure rather than absolute, so they don't take into account changes to ambient.

Is that english?

Ah OK, no probs.

It's because boost controllers and gauges, tend to use gauge pressure rather than absolute, so they don't take into account changes to ambient.

Surely if the boost controller shows 1.3bar instead of 1.2bar that it is set to it is not doing its job though?

Would I be right in saying that an increase in the boost during the winter is in actual fact a wrong reading and that the turbos aren't infact under any more load than normal then?

Most boost controllers you don't set a pressure, you set a duty (a nominal figure between 1 & 100 say which is how fast it opens & closes the solenoid), so when you say I set my car to 1.3 BAR, are you actually inputting 1.3 BAR? Well the DSBC worked like that

it should be 4th gear mate, it's right under 3rd gear...

you're right ... next time I should take you with me on the passenger seat in case I'll forget

Most boost controllers you don't set a pressure, you set a duty (a nominal figure between 1 & 100 say which is how fast it opens & closes the solenoid), so when you say I set my car to 1.3 BAR, are you actually inputting 1.3 BAR? Well the DSBC worked like that

Ahh, maybe that is why I have never had an issue. I don't have a boost controller and previously I used a manual boost controller so it wouldn't have the same issues as the electrical one might... if what you suggest is the reason