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The mkiv Supra Owners Club

Did a full decat----NOOBish Question


Guest NateZM

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Hey guys,

 

Well I fully decated my exhausted system with a custom made downpipe and mid pipe from the back of the turbos to a Blitz Nur Spec back box. However i didnt put a restriction ring in, but heres the funny bit.... i still see standard .8bar of boost, it hasnt once overboosted to above the fuel cut. The car has an uprated fuel pump, blitz fuel computer, blitz intake. Surly once i decated my exhaust and with the extra help of the other mods, it should have shot past fuel cut? my turbos work very well, they never once miss a beat, first comes in perfectly, and the second turbo chimes in nice and strong around 4000rpm.

 

Any ideas...

 

Ps... Its a VVTI auto

 

 

thanks in advance.

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Had a car in here a bit ago that had had a full home de cat yet never made more than about 0.7 bar boost. Found it had obviously never run on both turbos in years. Fixed the problem, road tested AOK, a strong engine! gave it the customer, got paid, told him it would be very frisky as it was on junk tyres, and to be careful, it was a different beast. He got 10 miles up the road and put it in a ditch :) Is it FOR SURE coming up on both turbos??

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The diameter of the piping is all 76mm right to the back box, which i think is 3inch piping. Its all clean and as straight as can be right to the back box. Im 100% sure that both turbos are coming online as you get a small rush, and then at just over 4000rpm a much larger rush. From what i can see, or can tell the turbos are all original j-spec. Im wondering now, maybe either there is a large restriction early on in the downpipe area. Would changing the spark plug release this unfound boost? i have had no missfires from the spark side of things what so ever. I have a boost controller coming in this week, i will hook it up and slowly try and up it and see if it starts to go heywire. iv come across this in other fourms when iv tried to search, but no one can ever explain what they found.

Edited by NateZM
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