problem raising boost

[philsmith1a]

I have just fitted a double decat to my j spec tt, after fitting with a 52mm dia. RR it ran .9bar, I filed it out to 54mm and it is still .9bar. iv got a walbro pump but not yet fitted. The exhaust is a 3” blitz nur spec r.

I doubt the boost isn’t rising due to the lack of a decent fuel pump, can anyone suggest what the issue could be?

[clapyohandz]

Have you checked all your vaccum lines ? I can get to 1.5 bar with the RR on...

[Lude]

i wish my boost would be that low.

 

 

tbh mate, your better keeping it like that, then having a boost controller to increase the rest.

 

 

i have the Blitz nur & double decat also, boost goes 1.4bar

 

so its not you have a restrictive exhaust. either increase the Restricotr ring or get a EBC

[clapyohandz]

Or just toss the RR ?

[philsmith1a]

I have checked the vacuum hoses simply by having a feel around while some one revs the engine. Is there a proper method for doing this?

I would just get rid of the RR but i want to find a reason for it not affecting the boost

[clapyohandz]

Right underneath the first turbo there are two very tiny thin lines. I wish I could post a pic but I do not have my car next to me. If one of them is not properly routed, it might be the reason.

[philsmith1a]

i think i found the ones you mean (about 10mm outside dia.)? everything looks fine with them.

[Nic]

I would do the following, remove the restrictor ring, do a test drive and see if it'll boost higher than 0.9bar - be careful with your right foot not to boost too high. If it will boost higher then the RR is adding too much of a restriction at the moment and needs the hole increasing further.

[philsmith1a]

cheers nick. will do.

[Gambit]

I have the same thing.

 

I get .9 with cat, RR or straight through.

 

What smic do you have for the question?

 

Would a crap smic make a difference or knackered waste gate?

[philsmith1a]

Right, first off I misread the boost gauge, it wasn’t .9bar it was 9psi!

I’ve taken the rr out, took her for a run out and did a few high speed pulls and it did hit fuel cut once(at about 6500rpm)-boost gauge reading was 14psi. So I recon I must have a boost leak as the exhaust is 3” straight through or if there was a leak would the boost have stayed the same if it had a rr in or not??

 

Any ideas?

[richarde7927]

I have a the same sort of thing , i have a double decat ,nur spec , fuel pump ,front mount , bov valve , boost controller , induction kit , fuel cut defender ,

 

The car was all done when i got the car and the boost controller was already set up ,

In 3rd and 4th gear hard pulls it makes spikes at 1.15 bar and holds 1.03 bar in 3rd and 1.05 bar in 4th in 5th and 6th im only holding just under 1 bar. the boost controller is on max .

 

i know the car can make more as i have a pipe come off the boost controller one day and the car fit 1.8 bar , i let straight off as i know there was something wrong plus i had fuel cut ,

 

So why will the car not make and hold 1.2 bar , its been driving me mad for months .

 

The car is a j spec tt 6 manual there is a rr ring fitted but im not sure what size , i have brought a 1.2 bar ring to put in a try .

 

Rich.

[James]

To the original poster - do you have a fuel cut defender?

[Nic]

So I recon I must have a boost leak as the exhaust is 3” straight through

 

What exhaust model is it?

[philsmith1a]

I have a thor vfcc, not fitted at present as i wanted to make sure the boost gauge was reading correctly(i.e. fuel cut at 1bar).

 

The exhaust is blitz nur spec r with 3" decats.

[philsmith1a]

Just to add, after a drive this morning i left the car ticking over for 5 min, the exhaust started blowing loads of white smoke. it has never done this before, if it is the turbo seals could this be causing the low boost pressure?

[Chris Wilson]

Sounds like one or both turbos are on the way out. This could be very costly I am afraid. I am finding the majority of used front turbos I get to send for re conditioning have bad cracks in the turbine housing wastegate seat. These can be welded but often crack again. I recommend new ones from Toyota for true peace of mind, but I am unsure if anywhere still has stock as they have discontinued them.

[scotty71]

How much are new turbo's from Mr T?

[Chris Wilson]

They were over a grand each last time I checked.

[scotty71]

They were over a grand each last time I checked.

 

I thought I heard 1K each or around that:blink:

[Nic]

but I am unsure if anywhere still has stock as they have discontinued them.

 

I think it was the UK turbos that were in short supply, the J-spec turbos are definitely still available.

[philsmith1a]

Bad news! All I wanted was a reliable 400bhp.

I’m thinking I might be better off buying some second hand turbos, I have found some on ebay with 3 months warranty ,I can’t justify going single as it’s an auto and I have been advised against hybrids.

 

What to do??

 

Also should I stop driving it? If the seals went completely would I wreck the engine?

[philsmith1a]

I’ve sourced some very low mileage turbos, during fitting 3 cracked pipes were found so that was the boost leak sorted.

 

In hindsight maybe I should have kept the old turbos as they only puffed the smoke the once and that was with no RR. I’m guessing most turbos with no back pressure in the exhaust would allow a drop of oil into the exhaust after a hard drive and long idle.

 

Thanks for everyones help on this.

[Gambit]

So now that you've changed your turbo's and replace the cracked pipes, hows your boost?

[philsmith1a]

max boost is sorted. but now the 1st turbo wont spool up!