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The mkiv Supra Owners Club

obtaining more boost ??


daveyboy

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Standard boost for turbo1 is 0.75bar

Boost for both turbo1 and turbo2 is 0.8bar (sometimes 0.85bar)

 

With exhaust changes, removing CATs, you'd expect anything from 0.9->1.2bar. (or until you hit fuel cut at 15psi, nadge over 1bar)

I realise this is a large change and is due to many other factors. I changed both my CATs for downpipes and still only boosted to 0.9bar (much to everyones amazement)

 

Fitting a boost controller I could get 1.2bar so I was happy.

It wasn't until I went for hybrid turbos that I found the car was underpowered. Turned out to be my back section of exhaust section had internally collapsed and was choking the engine.

 

Sounds like you have replaced the back section as well, but did you replace ALL of it? or just the back box.

Remember the two mid boxes that split going around the rear diff. Have you changed them? This is where my problem was.

 

 

Use the bleeder "T" valve method (search will find stuff on that) and you'll get more boost. If the car struggles to get more power I'd look at the rest of the induction system.

Air filter and exhaust system.

 

Stupid thing but you are using Super unleaded and have a nice clean air filter and recently serviced spark plugs?

 

Checking the BOV is also an excellent idea.

Mine was working but the moment I upped the boost it knackered it. Didn't know again for quite a while, when someone else drove it. Got an HKS BOV and removed the stock one and whey hey! I was away!

 

 

Regards

Pete

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ok then back again. rite i have checked the bov(thanks for the help for identifying it) its good cant blow through it. my exhaust consists of : orgininal first cat box(gutted) then i made up down pipe off it with no second cat at all made of 2.5" . then at the joint it goes to one 3"pipe going to the back box. thats it. i have checke the back box and can see through it no problem so it not blocked. as the overboost light has not come on i checked to see if there is a fcd. there is not one. i checked and cleaned hks induction filter ,all was ok. i havnt shecked the plugs yet but i will do later on tonight so i still dont know why im not getting the extra boost???

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yes the cat is clear looked through it yesterday. ive just cleaned the plugs . a little dirty but not bad. tinge of white on them but still good.so what now ??? am i loosing the boost. ive checked all pipes and connectors and they all look good. baffled??????

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PETE !

 

I changed both my CATs for downpipes and still only boosted to 0.9bar (much to everyones amazement)

 

NO MATE, not amazed....

 

I've decatted (both) and have NUR-R and reckon from feel and

1/4 miles of ~14.1 (consistent) I'm only ~ 0.8-0.9 Bar ? !

[NO restrictor ring... etc]

 

I'm just gonna go and buy a Boost Guage (bit late really ! !:eek: )

 

AND, if they've got an 'adjustable' one, a Bleeder-Tee bleeder:p

 

YES, I know a controller's MUCH better, but I want to try a simple

mechanical one first so I KNOW what it's/I'm doing..... (I can just

about get my head-around a screw cutting-off the Actuator feed -

but once there's solenoids/ins&outs/electronics.... ?!?)

(plus.... I'M a MISER:sly: )

 

I'll report back on readings once Guage is in (on?) AND feedback

if/when I get a BLEEDER.

 

FatS.

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