BPU tech article - for review

[Carl]

Excellent Article.

For someone like myself who will be going BPU after Christmas, this sort of info is very usefull.

 

Carl

[JohnA]

I wouldn't be comfortable with calling 1.2bar as 'safe', because it isn't. People have killed their turbos at 1.2.

I'd only call it 'safe' up to 1 bar.

[mikeyb10supra]

Is there anyway to make this a hotlink on the newbie section?

[Thorin]

I wouldn't be comfortable with calling 1.2bar as 'safe', because it isn't. People have killed their turbos at 1.2.

I'd only call it 'safe' up to 1 bar.

 

People have killed their turbo's at 0.7.

[JohnA]

Not from overspeeding due to the modification though.

Perhaps they had a leak or another fault.

[Ian C]

My general comments:

 

1.2bar is the accepted safe limit with regards to a) detonation, b) actually getting more power, and c) some level of longevity.

 

It is also accepted that you are spinning the cylinder and pulling the trigger each time you use them, but 1.2bar you have one loaded chamber, 1.4bar you've got three

 

I'd say iridiums last longer than 8000 miles, for ten quid a plug they had better

 

EGT temps above 950degC are dodgy, anything above 1000degC is A Bad Thing. Anything under 950degC is OK, providing the sensor is in the pre-turbo exhaust stream. Installing it post-turbo introduces such a big and variable heatsink into the equation it's pretty much useless. People take anything from 100 to 250degC off the aforementioned maximum, meaning that your gauge could read 800degC and mean anything from imminent meltdown to running nicely. No-one has put an EGT sensor before and after the turbo and datalogged the variance so it's 100% guesswork, and that's the last thing you want on the ragged edge.

 

-Ian

[chilli]

I also thought iridiums last much longer than 8k, mine have been in for around that and it's never missed a beat.

 

Just to clarify, if you have a wideband AFR then an EGT is of no use for any other purpose? That seems to be what is being said.

 

Excellent article btw, very clear and informative

 

PS: is it worth mentioning that the intercooler (stock smic or even aftermarket fmic) must be in good condition to cope?

[Homer]

My general comments:

 

Thanks Ian, I've updated (copy pasted ) where necessary

 

I also thought iridiums last much longer than 8k, mine have been in for around that and it's never missed a beat.

 

Just to clarify, if you have a wideband AFR then an EGT is of no use for any other purpose? That seems to be what is being said.

 

Excellent article btw, very clear and informative

 

PS: is it worth mentioning that the intercooler (stock smic or even aftermarket fmic) must be in good condition to cope?

 

The iridium milage was based on my own expereince but this doesn't appear to be the norm, so have updated that line

 

Good point on the IC, just added that as something to check at the end.

[supRo]

In my experience I found the Iridiums good for 11-12K miles then the car becomes less responsive.

I still use Iridiums (IK24) on my BPU Supra as I find they make the car more responsive than the NGK copper ones.

[Ian C]

Just to clarify, if you have a wideband AFR then an EGT is of no use for any other purpose? That seems to be what is being said.

 

Nope, not so. The EGT gauge is still useful. If your intake charge gets too hot, the exhaust system too restrictive, the turbos move far enough out of their efficiency, too much boost, wrong grade of fuel, and so forth, the EGTs can go up regardless of AFR. It's a warning system, not a tuning system. And at 1.2bar on stockers with their restrictive housings and manifold, it's a very handy warning system.

 

-Ian

[Spoony]

really cool article!!

if this is ok for you, i will copy it with your name to our german mkIV homepage

[Homer]

if this is ok for you, i will copy it with your name to our german mkIV homepage

 

Of course, its in the public domain after all

 

Rather than reference my username could you reference the club URL? Cheers

[Spoony]

thanks!

 

one question.

why buy expensive decat pipes when most of them just have 2,5 inch. original is arround 60mm i guess, so its not the biggest win.

wouldnt it be the same when i cut the cats out and burn a 60mm pipe in the original downpipes? or are the oem pipes much worse?

[Homer]

thanks!

 

one question.

why buy expensive decat pipes when most of them just have 2,5 inch. original is arround 60mm i guess, so its not the biggest win.

wouldnt it be the same when i cut the cats out and burn a 60mm pipe in the original downpipes? or are the oem pipes much worse?

 

Chris Wilson has always said there's no point going larger than 2.5 inch diameter when going bpu. The stockers are 2.25 inch so would probably be fine if you wanted to chop them up. Many of us here like to keep the 2nd decat pipe intack for when MOT time comes up. Its a yearly thing here, I think the same as the German TUV test, though probably easier to pass.

 

Anyway, decats are cheap, and we all like to boast of 3in/4in pipes rather than hacked up stock stuff

[Spoony]

ok i understand,

my plan is to put a 100 cell cat in place of the 2nd cat. only for the eye. i know some garage who have really old machines to test when you have to pass the tüv exhaust co2 test. they mostly give you the passed test without making so much trouble about the results

 

i thought maybe the decat pipes have a better flowing, but if the flow is the same and only 5mm difference i will cut it on my own.

 

or do you have a adress for cheap 3" decat pipes?

thank you again!

[Homer]

or do you have a adress for cheap 3" decat pipes?

 

I think Paul Whiffin & Miami-GT can supply cheap 3inch pipes, also worth a try is Turbofit (Though I'm not familiar with their prices).

 

The cheapest I've ever seen is the a full decat pipe made by "Megan", I think these go for the £150 mark which is seriously good value if you are okay with a single pipe.