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Planning on Going BPU


Class One

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I forgot to mention. I'm running the stock BOV, will this be able to handle the extra boost pressure or should this be upgraded as well? BTW i only ask from a performance viewpoint not as some chav type wooshing noise thingy!

 

From what I've heard from others .. the stock BOV will be fine.

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Hi,

If money is not too much of an issue, I would recommend an EBC with a 1 bar restrictor ring.

Why? If your running 1.2 bar all the time, after a while you get used to the power and it'll feel like how it was when it was stock!

I normally drive on 1 bar (EBC switched off). For those spirited moments I whack the boost up to 1.2 bar at the touch of a button, more power, quicker spool and turbos coming on a bit quicker. This makes the car much more enjoyable than constant fixed boost in my opinion.

 

Stock BOV will be fine.

 

Ro

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I forgot to mention. I'm running the stock BOV, will this be able to handle the extra boost pressure or should this be upgraded as well? BTW i only ask from a performance viewpoint not as some chav type wooshing noise thingy!

 

Stock BOV is fine. To be honest, I've no idea when it would become a problem, but if you have a boost gauge, you'll soon find out if you start having difficulty sustaining boost. I'd guess you won't have that problem on stock turbos though.

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I would think hard before running a JSpec beyond 1 bar.

 

The chances of sudden catastrophic failure increases a lot, and the extra performance isn't worth it IMO.

That way you can enjoy (almost) stock reliability and avoid fuel cut defenders or fuelling upgrades. Even intercooler upgrades. Hell, even fancy EBCs.

The overspeeding of the turbos beyond 1 bar may not be worth the aggro if you intend to keep the car for some time.

The scenery is littered with blown turbos from running 1.2bar or more. Most of the supras off the road or running singles (or hybrids) ended like this from overspeeding the stock units.

 

If you're hellbent on running 1.2bar, just get a dyno figure from 1 bar and 1.2+ bar. Then decide if it's worth running on the edge (some have run them at 1.3bar for years before failing, others for weeks. Do you feel lucky?)

 

Just my 2psi

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Fair point, I'd be more worried if it was a manual boost controller and it was set to try and hold 1.2bar though.

 

Anyone got any stats on failures at around the 1.2 mark? mine was noticeably quicker from 1.0 bar to 1.2 so for me it was worth it, but not if very premature failure is a dead cert!

 

Anyone else care to comment?

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I know how people feel about 'boost' so I don't expect the above post to make me many new friends.

 

I did actually think of keeping my mouth shut, but I feel that Class One is a decent guy and deserves the reply, even if it isn't (by current standards) totally "politically correct"

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lol true, I don't expect my tubbies to last forever, so long as MTBF is ridiculously reduced so as not to make it worth while!

 

It's good to speak up John, fair play to warn everyone of the risks you take with this sort of stuff - just wish there were some better statistics on this sort of thing but people don't like to admit when they've blown their motor up.

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You pay to play. :tongue: It's that simple. :shrug:

 

Very true. I now run sometimes way over 1.3bar myself :blush: (although it's a UKSpec)

 

The difference is that I am fully aware of the risks and do it mainly for experimental reasons - hence I have a spare set of recon turbos in my garage.

There is nothing wrong with playing with fire, as long as you are prepared to treat the burns.:violin:

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There is nothing wrong with playing with fire, as long as you are prepared to treat the burns.:violin:

 

Very true. There is only so far you can take the stock tubbies.

I daresay, there are some J-Spec BPU members that they're turbo's have lasted a few years since midly modding.

 

Oxy's turbo's died and he was only on stock 11.5psi. Whereas my stockers lasted 9 months after decatting & running 17psi.

 

It appears somewhat of a lottery about turbo's doesn't it ?

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It appears somewhat of a lottery about turbo's doesn't it ?

 

Completely, was going to post the same thing myself!

 

Mine has been running 1.2 bar for 2 years and 30k miles, most of which have been a WOT. It's still going strong and (apart from the startup 'puff') no smoke so far. I know its only a matter of time before they go pop...

 

If you go BPU then yes there is a risk they go, if they do then just replace them/upgrade!

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I've been running 1.3bar on my j-spec for almost 5 years now in TTC mode, touch wood no problems, although I do have upgraded fueling, FMIC and have the emanage mapped for this boost level. There is a huge power difference between 1bar and 1.2 or 1.3bar. Yes it may be a bit of a lottery, but definitely worth it IMO for the added power.

 

Saying this, if I didn't have the supporting mods listed above, I think 1.1bar would be the max I would run on stock fueling, ecu and IC.

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John, thanks for your honest post.

 

I'm well aware of the probs associated with taking the BPU step, some have been lucky others haven't which is why I wanted to mainly run the car at 1 bar then using an EBC to up the boost to 1.2 bar for the occaisional jaunt.

 

I mainly run in (E)TTC mode now anyway, much safer in the current weather IMO.

 

Its funny how you mention about compairing dyno charts between stock and BPU. I ran 262rwhp at Surrey RR last year on a (mainly) warm day on a practically stock set up (only a HKS panel filter in the stock airbox.)

 

Terrible Turner ran something like 340rwhp or somewhere abouts.

 

However, compare that to "on-road" performance, there wasn't much in it on our spirited run to Silverstone (eh James:p ?). There was no denying James' car was quicker than mine, but it needed a long bit of road to make it really count.

 

Which is why it has been a bit of a hard decision to make, because at the end of the day, like 99% of people who got BPU or single etc the reason they do it is to make the car go faster isn't it?

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From what I've seen on the dyno the gains (bhp/extra psi) tail off after 1 bar.

The turbo shaft rpm however go through the roof (judging from compressor maps of similar units)

 

The extra bhp/psi also depend a lot on fuelling, intercooling and timing --- something that can vary a lot depending on the specific car.

 

I have not delved deeply into the behaviour of the stock JSpec, but my guess is that over 1 bar the AFRs become leaner, hence the rise in power between 1 and 1.2 bar that people experience. As the AFRs go towards 12:1 maximum power is achieved (albeit at the expense of further erosion of the safety margins)

 

This, however, does not affect the risk of overspeeding the stock turbos. Neither does the installation of a FMIC.

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