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Unusual Lag Problem

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By byebye,
in Engines & Forced Induction

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byebye Community Regular

byebye

Posted
Posted

I bought a r32 gtr and always thought it was too laggy for stock turbos but after checking everything i could think of just decided thats how it was.

I bought a power fc, adjustable cam gears, boost controller and took it to a dyno tuner that was very highly recommended where he informs me that this is not normal so after a full day of him checking everything its making 200awkw on 12 psi which is apparently about right but it doesnt make full boost til after 5,500 rpm it just builds up slowly

Has anyone heard of this? cam timing has been down by the marks and the amount of teeth on the belt, no vacuum boost leaks, turbo actuators have heaps of pressure on them, i have inspected the compressor wheels on the turbos, swapped intercoolers, air filters arent restrictive, really the next thing is to inspect the exhaust wheels and the flaps to make sure they are sealing but because thats not a fun job i thought id see if anyone else has come across this problem and my tuner has never had this happen before

Standard turbos, standard manifolds (no exhaust leaks) im assuming just no brand stainless dump pipes the kind that seperate the wastegate from the exhaust and the plumb back in (which im not a fan of)

cheers

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Moodles2 Grand Master

Moodles2

Posted
Posted

Since it's a 32, it's possible you have the 32 Nismo turbos, steel wheel and the laggiest of all the garrett turbos with steel wheels. Even with them though full boost at 5500rpm, should be seeing full boost much earlier maybe about 4000rpm instead if you indeed had them.

DVS JEZ Grand Master

DVS JEZ

Posted
Posted

Have another play with the inlet cam timing. My mates was doin the same thing and adjusting the inlet cam netted a much better response. About 800rpm difference.

This was with 32 nismo turbos.

His was the same 5500, now 4700rpm and makes 300kw on 19psi

Harey Veteran

Harey

Posted
Posted
well im pretty sure i didnt have any and the tuner checked too, once it gets to 12 it holds it fine? isnt it still laggy for n1s? and shouldnt it of made more power? i guess the engine could be tired

thanks for everyone input

The fact that it holds 12psi doesnt mean that its not a boost leak, the turbo/s are just working much harder to keep it at 12psi. Mine ran exactly the same boost pressure just took longer to get there for the turbos to overcome the leak. If it was a huge leak then yeah maybe it wouldnt be able to hold 12psi but a smaller leak would.

Can be hard to hear especially if its while the engine is running. I just blocked off the pipe running into the engine and made up a fitting with pvc pipe and used a hand pump to pump air into the system. Was super easy to hear where its leaking out cause there are no other noises. Cost me $20 for a hand pump and $6 for 2 pvc caps.

byebye Community Regular

byebye

Posted
  • Author
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Might have to compression test it, kind of been putting it off because then i might have to rebuild it! makes sense harey ill give it a go, easier than taking the dump pipes off to check if the flaps are sealing which is all i could think of to do next!

cheers guys

MrStabby Grand Master

MrStabby

Posted
Posted

You could also try removing the boost signal to the actuators and give it a very careful run to see if they spool earlier. Boost will keep rising so shut it down as soon as you see boost build so you dont blow the turbos. If they are truly stock turbos you'd want to make sure you didn't push it past 3000rpm. If you're at 4000rpm with still no boost then you can be certain its not a boost controller problem.

BH_SLO32 Proficient

BH_SLO32

Posted
Posted

My first R32 had a "Hiclone" installed in the intake pipe making it much harder for the engine to breathe and consequently made the car feel very laggy. Once removed it behaved normally. A similar restriction somewhere from the air filters to the intake plenum would cause this problem. Your intercooler is not partially blocked? If you really wanted to get technical you could measure the pressure drop across the intake system.

byebye Community Regular

byebye

Posted
  • Author
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ive tried another intercooler and lower piping and had the other piping off but i have never heard of a hiclone! one thing is the afms are reading around the same volatge so each turbo should be sucking the same amount of air which is swinging me towards a boostleak/restriction

  • 2 weeks later...
byebye Community Regular

byebye

Posted
  • Author
Posted

taking vacuum lines off actuators didnt make any difference, i did end up having a inlet manifold gasket gone but that hasnt fixed it. replaced anything thsat looked even half dodgy (hoses etc) still no better!

thinking it has to be turbo related? funny thing is the afm reading is around the same

XKLABA Grand Master

XKLABA

Posted
Posted

taking vacuum lines off actuators didnt make any difference, i did end up having a inlet manifold gasket gone but that hasnt fixed it. replaced anything thsat looked even half dodgy (hoses etc) still no better!

thinking it has to be turbo related? funny thing is the afm reading is around the same

remove the cat wire up rest of exhaurst and take for a run around the block, it will be very loud but will remove any possible restriction in exhaurst and help rule out exhaurst, split dumps are better

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