Need Some Advice

[l0WRB]

Based on what testing?

full custom 3" system with gutted cat completey hollow with a 3" inlet xforce canon.. i dont see how this can restrict it enough to drop the boost down between changes and cause lagg? it makes the numbers just takes 6000rpm 2 get there

[GTScotT]

whats the progress son?

[paulr33]

ive checked out the video and had a listen to it a few times

the setup you have is defintely considerably largier than one would expect under normal operation

yes the turbocharger you have in question is a large unit, and yes its going to be laggy, but how laggy is the question

from the thread so far and number of suggestions you have highlighted one key fact that stands out with alarm bells ringing

"yeah as far as i know the vct is set to kick in at 3000rpm because at 2000rpm it was causing a slight throttle miss fire"

"found out from tuner its from 3000 to 6000rpm"

this is a key change in the engine characteristics and setup

the factory setup is on at 1800rpm and off at 4700rpm for the basic specifications

this provides the engine with a nice solid response all the way through the rev range and makes the engine crisp on the throttle

this is the optimum setting for the factory setup and coupled with a good tune of the AFRs and IGN map the car is amazing to drive (stock turbo etc)

with your setup it appears the turbocharger responds well (you can hear it wind up instantly), the car sounds loud and fast

ie the engine is making response / power and it sounds like we can hear boost and so on

its just the engine is lacking its punch, aka i suspect because VCT is on so late, the engine is essentially sluggish

there is enough exhaust gas and road speed to wake the turbocharger up and bring on some boost (you can hear it spooling away) but not enough to bring on full song

the end result is, you have a sluggish and underperforming setup consistently until you reach the normal VCT kick off point past 5000/6000RPM where its ineffienct to keep VCT on

so

my recommendation is

1) put to the VCT back to the factory specs

2) debug why it misfires at 2000rpm

3) re-check the complete tune now that VCT is fixed

4) re-test

i suspect the car will be very different to drive

[R31Nismoid]

full custom 3" system with gutted cat completey hollow with a 3" inlet xforce canon.. i dont see how this can restrict it enough to drop the boost down between changes and cause lagg? it makes the numbers just takes 6000rpm 2 get there

You mean a 2.5" cat.

That will cause no end of problems. Simple as that. Add to the fact it's not "piped" so there is even more turbulence going on.

[GTScotT]

the term your looking for is turbulence.

the step down in size in the exhaust causes turbulence which slows down the flow of exhaust gas backing up the system. once the gas slows it cools and causes friction on itself, causing it to slow further and further preventing you from spooling.. till suddenly you get enough gas thru the turbo to spin it. next gear and ur back where u started, pushing shit up hill.

that and the VCT issue paul has mentioned... poorly functioning VCT can and will make the motor a DOG to drive. you dont want to go building a turbo around these issues for the sake of it.. you want a turbo that works to your expectations when the motor is running how it should be.

[l0WRB]

the term your looking for is turbulence.

the step down in size in the exhaust causes turbulence which slows down the flow of exhaust gas backing up the system. once the gas slows it cools and causes friction on itself, causing it to slow further and further preventing you from spooling.. till suddenly you get enough gas thru the turbo to spin it. next gear and ur back where u started, pushing shit up hill.

that and the VCT issue paul has mentioned... poorly functioning VCT can and will make the motor a DOG to drive. you dont want to go building a turbo around these issues for the sake of it.. you want a turbo that works to your expectations when the motor is running how it should be.

thanks for the info paul.

i pulled the turbo back off thursday morning and sent it back to hypergear, then we are going from there

im pulling the stock manifold off the car this time and running a hi mount setup with larger dumpipe, still going to use 50mm external gate setup off the manifold, should be able to run a larger dumpipe and i will also look into gettin something other then a stock gutted cat.

once this is all done which should be in the next week or 2 it will hit the rollers again and see how we go

Edited February 12, 2010 by l0WRB

[GTScotT]

sounds promising, look forward to seeing the results

[paulr33]

hi mount, low mount, internal, external, twin, single - i think its irrelevant in your case

the engine is not running as it should, you can tell, you can hear it wind up and come on boost, but theres not enough exhaust gas for full song as the engine isn't working optimally

its basically running at like 60% capacity, and when it peaks past 6000rpm VCT kicks off (as your link says to) and hey presto its running as per normal

fix the VCT

retune

away you go

stop changing things

the more things you change

the more guessing games and youll never nail it down to what it was

[l0WRB]

yeah i know this but hi mount setups look sexy haha and give that really nice growl so once this is done no more fiddling time 2 leave it as it is and go from there

[The Bogan]

I had one of those purple cheapo gates from otto and it leaked bad, In the process of replacing it with a Tial.

Should get car back next week and Ill keep you informed on the outcome, tuner said it will come on boost quicker with a better gate.

[l0WRB]

thanks for that mlr.. let me know how u go because i thought there wasnt much 2 a wastegate at all? most of them all work the same?

[kwickr33]

thanks for that mlr.. let me know how u go because i thought there wasnt much 2 a wastegate at all? most of them all work the same?

No. If the piston doesn't seal perfectly you will get hug amount lag. It will be constantly leaking manifold pressure.

[GTScotT]

that and the design contributes to its operation. internal design quality and actual build quality will go a long way to make sure it operates how its meant to.. a poorly constructed gate is likely to creep like mad.

[The Bogan]

No amount of hugging will fix my wastegate,LOL, sorry.

The gate was the probably the main culprit for the loss but the cracked manifold I had wasn't doing it any favors either.