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Bpu @ 1.1 bar


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  • 1 year later...

Just been reading on the over the pond site, people running 22psi (slightly over 1.5bar) on stock twins?!

I have never upped my boost despite my car being bpu, just no boost controller. I think I remember reading 1.2 is about where people set it too, is that right?

would that make much of a difference to your dyno? If you had 1.2 instead of 1.1?

Edited by jackso11 (see edit history)
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9 hours ago, jackso11 said:

Just been reading on the over the pond site, people running 22psi (slightly over 1.5bar) on stock twins?!

I have never upped my boost despite my car being bpu, just no boost controller. I think I remember reading 1.2 is about where people set it too, is that right?

would that make much of a difference to your dyno? If you had 1.2 instead of 1.1?

I dont know about the difference you would see between 1.1 & 1.2 bar but i would imagine you would feel a difference in your bum dyno. 

I run 1.2 bar which is acceptable but I think it is like most things they werent originally desinged to run more then 1bar, therefore you will be effecting the life of the turbos, by how much i am not sure. 

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Seem to recall my old J Spec turbos were at around 1.2 -1.3 bar, worked fine for a year or 2 right up until i decided racing a motorbike was a good idea and they ended up shooting out the exhaust pipe 😁

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On 11/15/2020 at 10:08 PM, jackso11 said:

Just been reading on the over the pond site, people running 22psi (slightly over 1.5bar) on stock twins?!

I have never upped my boost despite my car being bpu, just no boost controller. I think I remember reading 1.2 is about where people set it too, is that right?

would that make much of a difference to your dyno? If you had 1.2 instead of 1.1?

I believe the USA stocks are similar to the UK turbos with steel vanes. 

The squiffy bhp is similar to what my car dyno tested at around 16 years ago even though it all looks stock under the bonnet bar a small snorting Blitz BOV and there is no boost gauge or controller anywhere. Maybe its just a special engine with whatever Japanese magic dust that was once sprinkled but whatever it was it has proven to be 100% reliable over more than 2 decades. I assume that I have stock ceramic turbos fitted, though I wouldn't know for certain as they have never been removed during my ownership.

So the bhp levels are good for a long stress free life, is it worth reaching for that extra 20bhp and risk throwing the cars impregnable reliability out of the wastegate?

Edited by rider (see edit history)
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On 8/15/2019 at 7:40 AM, squiffy said:

That's a good result! I had my bpu tt6 dyno'd last week and got 351 at the wheels. But yours seems to show your 1st turbo is doing more then mine is! 

 

 

Does your car have a FMIC or SMIC? One advantage of a FMIC that I have read is the cooler air input allows the turbo to spool faster which may be a reason. Probably Summer to Winter air temperature does to. 

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12 hours ago, rider said:

Does your car have a FMIC or SMIC? One advantage of a FMIC that I have read is the cooler air input allows the turbo to spool faster which may be a reason. Probably Summer to Winter air temperature does to. 

A non ducted FMIC will be worse that the OEM SMIC if condition is comparable. A FMIC will also add lag.

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1 hour ago, Mike2JZ said:

Not really.

So air velocity plays no part in lag? A larger area to pressurise will make no difference? A non-ducted FMIC vs ducted SMICboth new condition, zero difference?

With the greatest of respect Mike, unless a turbo and FIMC are properly matched I would have to disagree.

Surely a small turbo with a large intercooler will flow at a slower rate due to having to move more air in the system. Could this set up not also have the potential to cause a drop in boost pressure?

 

Edited by Frank Bullitt
Finally managed to engage brain. (see edit history)
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As a side, temperature does have an appreciable impact on air density; essentially the amount of oxygen entering the engine. For every 5C the amount of oxygen raises or lowers 1.7% at sea level. So you'd expect a winter dyno run to return higher bhp than a mid summer run on the same setup vehicle. There is a rough rule of thumb of a 3% power loss for every 1,000 foot elevation due to thinning air so its just a calculation away to work out how much bhp is impacted per 5C temperature change. If anyone can be bothered, I lost the will to take it any further.

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On 11/21/2020 at 2:29 PM, rider said:

As a side, temperature does have an appreciable impact on air density; essentially the amount of oxygen entering the engine. For every 5C the amount of oxygen raises or lowers 1.7% at sea level. So you'd expect a winter dyno run to return higher bhp than a mid summer run on the same setup vehicle. There is a rough rule of thumb of a 3% power loss for every 1,000 foot elevation due to thinning air so its just a calculation away to work out how much bhp is impacted per 5C temperature change. If anyone can be bothered, I lost the will to take it any further.

I believe hot air is less dense and holds less oxygen than cold air. This means turbos have to work harder, spin faster and compress more air to produce the same amount of boost it would at lower temperatures. Which would help explain why water injection kits work so well.

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