BPU'd and hitting 1.3-1.4 bar ?!?!

Afternoon all

Just got my car back from having a new BOV fitted due to my old one having quite a substantial boost leak

I cant for the life of me realise why my boost gauge is saying im hitting just over 1.4 bar on stock turbos ?!?! surely this is totally bad for the twins ?? or so ive heard anyway...

whats the best way to lower the boost as i know a boost controller wont do this. which cat is most restrictive 1st or 2nd ?

any help would be great as id like to keep both my turbos running

oh and i have a BPU Jspec auto TT 97 facelift

lets hope your boost gauge is knackered

Well i did think that but it was running fine before the boost leak was fixed.... or has it been buggered ever since i put it in ???

guess i will never know untill i get an electronic gauge in there, or get it dyno'd soon

wastegate not oppening?

Have u got a restrictor ring fitted?

A BOV change cannot increase boost (unless there was a pre-existing problem), something else is going on. Can you detail all your engine/exhuast mods to date?

Have u got a restrictor ring fitted?

yer i think its a 1 bar restrictor ring but dont hold me to that as my memory is like a sieve but yes i do have one.

A BOV change cannot increase boost, something else is going on. Can you detail all your engine/exhuast mods to date?

I know it cant, im just saying its cured my boost leak and somehow with my boost running through the pipes all fine, it seems it has gone up a few notches on the gauge.

Ok this is what i have, from what i can remember and i have had done:

Full BPU mods including,

grade 7 ngk irridiums

Greddy FCD

Full decat with ( i think) 1 Bar RR

Full stainless Motoria exhaust

FMIC , not sure on the make

Boost gauge

HKS SSQV Type 3 ( brand new model)

Walbro fuel pump

and from memory thats all i can think of but im sure i have forgotten something

just out of curiosity which is the less restrictive cat ? just so i can put that back in to lower the boost a bit for the mean time (i hope)

If all of the above is correct there's only two likely causes:

1) The wastegate or actuator is not working or plumbed correctly

2) The RR is too large

The 1st cat is the most restrictive but you should never use one with BPU, if you do want to fudge it, fit a 2nd cat, but I would not recommend it. I.e. solve the problem first, don't mask it

If all of the above is correct there's only two likely causes:

 

1) The wastegate or actuator is not working or plumbed correctly

2) The RR is too large

 

The 1st cat is the most restrictive but you should never use one with BPU, if you do want to fudge it, fit a 2nd cat, but I would not recommend it. I.e. solve the problem first, don't mask it

very true good sir, i will have a new 1 bar RR fitted and then go from there.

thanks for your help homer and co.

just a quick update if anyones about to advise me otherwise

Just rang my local performance specialists (SPChorsham) and the mechanic Phil who has a single supra himself advised me that putting the 1st cat will most certainly drop the boost and wont harm the engine, but as homer rightly said masking the possible problem isnt a good thing.

I Dont really want to put the cat back in as this will negate the point of being BPU but without seeing where i can buy a 1 bar RR i have no choice.

if i am currently peaking at 1.4 bar with RR and full decat, how much bar will i be looking at with just the 1st cat back in place with no RR , i haveto pop a cat in there for my MOT so i thought why not leave it in there if the boost is fine after ??

If someone can suggest another alternative then im all ears

Easiest solution is just to fit a restrictor ring with smaller hole in.

Yes fitting the cat will create a restriction lowing the boost (by how much is difficult to say it will depend on the car, exhaust fitted and condition of the cat), but it will also slow the spool up of turbos and lower the power. If you do decide to fit one of the cats fit the 2nd one as that is the less restrictive of the 2 and a lot easier to get at.

Do you have a boost controller fitted?

Good point made nic, i think i will do some running tests with 1st and 2nd cats one at at time and see how it affects the boost and power etc

Pistonbroke: no i dont currently have a boost controller fitted but i do have one just waiting to be fitted.

does anyone know where i can aquire a RR with a 1bar hole or smaller ? as i think putting the cat in is my last resort.

Whifbitz my friend.

Failing the new RR not working just get a cheapo mechanical boost guage from egay and see what it reads or borrow one.

i have a boost gauge from ebay already lol but not sure wether to trust it fully, on full boost its reading just under 1.5

i did think whifbitz as my original one is from them so im just thinking will it be the same ??

i have a boost gauge from ebay already lol but not sure wether to trust it fully, on full boost its reading just under 1.5

 

i did think whifbitz as my original one is from them so im just thinking will it be the same ??

Run the both at the same time then with t-piece and if one reads say 0.2 - 0.3 bar different then it may be the gauge.

You'd have to ask Paul. Chris SWilson will also be able to help you out. I'd imagine all our traders would.

i did think whifbitz as my original one is from them so im just thinking will it be the same ??

Remove the RR you have fitted and measure the hole in it, then buy one that is smaller.

Will do nic, working alot of daytime hours this week so cant get at it soon but hopefully ill have some the 1s and 2nd cats with me by next week so will try it all out next week some time.

Putting the first cat in would increase the EGT's potentially too high, i would have thought someone with their own car and half a clue would have known that.

Rob: i did say that to him and he said yes it would increase slightly but not enough to damage/harm anything, maybe he doesnt know as much as i thought

oh well ill have to keep this thread shut until i do some research with the cats and RR.

cheers for your help guys , much appreciated

You might as well check the wastegate actuator is working properly too, it's only a two minute job. Stick a foot pump onto one of the feeds and block off the other. It should start to open at 12psi and be fully open at 18psi.

the RR should be 5.1cm in diameter (don`t know in inches and too lazy to find out )