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BPU-ish


carl0s
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I fitted the 3" 1st decat pipe on Saturday, and the car is making more power, but I think there's potential for a little more.

 

The car is now making 15.5psi routinely, and hitting a general maximum of 17psi in high gears, with an absolute momentary peak of 17.3psi whilst on the motorway.

 

Ideally I'd like to see 17.5psi in first and second gear, not just top gear.

 

My SMIC is in fairly good condition, although I have a CW unit on order anyway. I still have the stock '96/97 fuel pump.

 

What to do? Any suggestions? Is it worth me fitting a second decat pipe at all?

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For anyone else that doesn't relate to PSI:

 

15.5psi = 1 bar

 

 

0.7bar*15=10psi

0.8bar*15=12psi

0.9bar*15=13.5psi

1.0bar*15=15psi

1.1bar*15=16.5psi

1.2bar*15=18psi

1.3bar*15=19.5psi

 

After removing both cats to achieve 1.2bar (and putting a restrictor ring) as I understand it you'd need a boost controller to raise boost in lower revs/gears rather than relying on the natural spin from the free flow of the exhaust gases.

Boost gauges generally tend to over read slightly too, like speedos they keep you on the safer side of things.

 

Your standard fuel pump is fine for BPU.

 

Have you got an FCD yet? That'd be the first thing I think.

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Thanks Pete.

I've always thought PSI was the better unit to use, since it's higher resolution IYSWIM.

 

I have fited the Thor FCD.

 

I still have the second CAT in place, no restrictor ring present since the second CAT is doing that job..

 

So, potentially I need to look at a boost controller. I do have a manual bleeder valve which I took off the UK car, but using this would just give an overall increase in boost I presume, so I'd be peaking at 19.5psi just to get the 17.5psi that I want in lower gears, and I should think that's not a good thing is it?

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14.5 psi = 1bar heres a conversion table http://freespace.virgin.net/wiltec.systems/menu05/boost.htm and hers a conversion calculator http://www.centauro-owners.com/articles/psibar.html

 

I dont think EGT's go too high with just the second cat left in. I met a guy with hybrids who runs 1.4 bar with cthe stock second cat left in place, He did say he normally drives with it at 1.1bar (controlled with an EBC) but he had no problems

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just reading through the posts again and on a similar question to Carlos's post can you run 1.2 bar safely with a performance exhaust and first decat? (leaving the second cat in) I know one guy has been running 1.4 bar with hybrids on this setup but would the hybrids make any difference to the EGT's? Just thought I would ask as it seems relevent to this thread. I have a Nur spec R and a 2.5" first decat pipe and my boost kept creeping to 18psi before fuel cut. I put a rr in and a thor FCD and spend many attempts fileing the rr out (what a pain in the arse that was:( ) to get a nice steady 15psi but I was also going to buy an EBC to raise boost to 1.2bar (Il not convert that to psi this time :D ) will the EGT's be ok? I figure if the second cat cant control the boost (as in it alows boost creep to above 18psi) than it cant be too much of a restriction can it

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You'll read lots of things on here. ;)

 

Upgrade to a UK spec one if you like, they've more powerful. The Walbro one is more likely to pack up than the Toyota one.

 

That's kind of why I haven't just gone for the Walbro pump to be honest Pete. I raised the question recently about whether the stock UK pump was actually a Bosch 044, as had been suggested by somebody, but didn't actually get an answer.

 

People were saying the Bosch 044 doesn't like pulling uphill or something.. So, it's either a UK stock pump (sounds ideal.. why not), or a Bosch 044, or they're both the same thing anyway.

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So, Pete, and others..

 

What if I was to go with a second decat (I'd like to anyway just for the noise), and fit a restrictor ring so that I was running 17.5 psi (1.2 bar) most of the time, but with an occasional spike to 19psi (1.33 bar).

 

How would you feel about that? Would you see that as a Bad Thing™ or what?

 

Bearing in mind I had a brand new good quality SMIC, correct plugs, new fuel filter, possibly a newer fuel pump although fuelling at 1.33bar would be the same as at anything else above 1 bar (100% injector d/c as I understand it.)

 

This was all so easy on the UK car - big 3" one-piece decat pipe, an exhaust, and a bleeder valve :D

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Hi Carlos

 

The UK spec fuel pump is an excellent choice with really good flow rates as can be seen here:

 

http://www.mkiv.com/techarticles/fuel_pumps_test_2/index.html

 

 

As far as the turbo's and boost pressure is concerned i would be careful above 1.2bar mine when @ 1.2bar. Also there are no real gain after that because:

 

"There are limitations with pressures above 1.2bar, the turbos are already outside of their efficiency range and the additional heat generated will raise the intake air temperature considerably – thus negating the effect of increased boost pressure."

 

Here is the post that the above came from plus loads of other excellent info on j-spec BPU:

 

http://www.mkivsupra.net/vbb/showthread.php?t=92770&highlight=bpu+1.3bar

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So an EBC it is then. I know about the efficiency range etc and 1.2/1.25 bar being the 'safe' limit, but as it stands now I could only have 1.2 bar 95% of the time if I allowed for the other 5% of the time to reach 1.3ish bar. That is, without an EBC it seems.

 

I hate these electronic gadgets, they're messy and stuff but I suppose if it has to be that way then I have no choice.

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I presume you have a free-flowing exhaust?

 

Boost spiking can't be good for longevity of your turbo's. Personaly I'd take the cat out, put the ring on, then put a EBC on- think Robert has a Blitz one for sale (see for sale section/parts)

 

It is fairly free-flowing, although it's noticably more restrictive than an RS*R GTII, because it has a muffler in-line. It's a Greddy/Trust Power-Evo II or something. I really like it, but it was restrictive enough to lose me 2psi of boost after swapping the RSR for it (on the UK spec car).

 

Thanks for the tip on the EBC.

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That's kind of why I haven't just gone for the Walbro pump to be honest Pete. I raised the question recently about whether the stock UK pump was actually a Bosch 044, as had been suggested by somebody, but didn't actually get an answer.

 

People were saying the Bosch 044 doesn't like pulling uphill or something.. So, it's either a UK stock pump (sounds ideal.. why not), or a Bosch 044, or they're both the same thing anyway.

 

 

The stock UK pump is most definitely NOT a Bosch 044, or anything like it. It's not even made by Bosch at all.

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The stock UK pump is most definitely NOT a Bosch 044, or anything like it. It's not even made by Bosch at all.

 

It's Denso, right?

 

The forum's BPU Tech article here seems to think that it's a Bosch 044 :shrug:

 

I've found a price quoted from five years ago of £102 + vat. Steep, but not the end of the world..

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I've found a price quoted from five years ago of £102 + vat. Steep, but not the end of the world..

 

 

Check the price now, last time I did it was nearer £200 :blink:

 

Being as I have Carl0s's old double decat pipe to fit on mine now, would it be wise replacing my UK fuel pump or is there anyway of checking to see if it's tired with old age?

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