View Full Version : how a ct26 does on a quarter ...
cheers stu for pushing the button!.. the last run of the day 13.88 the first blip of pressure is stu giving it a small warm .. then you have gears one to 4. i wished id had the rev counter gauge.. could plot a nice graph. next on the foot long list .
http://s58.photobucket.com/albums/g259/adamhbrutal/?action=view¤t=ct26stuquarter.flv
that's pretty amazing to see how much boost it does drop over the gears. Would be very interesting to match that against revs. Nice job
Sponge Bob
08-10-2007, 23:43
That seems to be leaking a lot of boost... should it not hold it at the desired level rather than slowly dropping off!!
i went over the piping with a fine tooth comb before the day. as the rpm's jump up the compressor efficiency drops as it cant flow enough air to keep up with cylinder demands, not to mention the increase in intake temps through a long gear like 3rd.. where it dropped off and hanged 'ten' lol
weegaz22
09-10-2007, 00:06
what are you using to control boost adam? mbc or ebc?
3 port mbc mate, brass ball and spring type with small bleed hole in it for exhausting the actuator return air, it fluctuates a fair bit now and then, a good device essentially for the cash.
weegaz22
09-10-2007, 00:14
i know that the ct26 runs out its effeciency range at higher boost/rpm levels, but was just wondering if maybe your mbc is allowing a little more spiking than you want, then settling down
Sponge Bob
09-10-2007, 00:19
Or perhaps the actuator is weak...
ebc sounds the way forward unless i can design a better manual valve lol
:liar:
yeh good point ash, perhaps something pointing at the actuator assy. perhaps although isolated through the closed ball mechanism its maybe creeping open with a weak diaphragm, if i could get a vac feed into there somehow... have to think on some pnuematic tricks in the morn..
my boost drops to 0.7 too.
i've been told its normal for a ct26.....
i'd be dead chuffed if was the actuator
i used to have an apexi avc-r controller, it was exactly the same!
Sponge Bob
10-10-2007, 23:39
Well i've got mine cranked up a little with the charge cooler and it seems to hold what I tell it to fine... there's no mechanical reason why it should drop off surely, unless the actuator just isn't doing it's job at regulating the pressure properly?
It's nice to know that you can still go even faster though with a bit of tweaking Ad!! lol
weegaz22
10-10-2007, 23:50
Well i've got mine cranked up a little with the charge cooler and it seems to hold what I tell it to fine... there's no mechanical reason why it should drop off surely, unless the actuator just isn't doing it's job at regulating the pressure properly?
It's nice to know that you can still go even faster though with a bit of tweaking Ad!! lol
mines drops off to around 0.7-0.8 and i have the charge cooler from the st205, but could be a turbo thats getting a bit out of spec with wear and tear, wasnt there a thread in here not too long ago about it?
will be getting mines rolling road setup once ive bought new dizzy cap, rotor and colder plugs for it
Sponge Bob
11-10-2007, 00:44
Yeah, but if the turbo's damaged, why would the boost drop off... if there's enough exhaust pressure to overcome the friction of the turbo and spool up to a preset limit - e.g. 15psi, then the actuator will open up and bleed some off, but then it's up to the actuator to reclose and allow it to pick up boost again... so if it's not, then there must be a problem? Or am i looking at it too black & white...?
weegaz22
11-10-2007, 01:16
http://forums.twobrutal.com/showthread.php?t=9593&page=2
As the rpm increase the engine uses more air, if the compressor side of the turbo is damaged it may not be able to deliver sufficient volume to maintain the pressure at higher rpm.
ash.. when i was normal daily driving it would hold a good bar or just under, what to remember chap is i only ever ran it to 5-6krpm at tops on the road in short bursts usually just some overtaking or acceleration. and even at that speed i had no time to look at the clock or be serious and dumb enough to record it on the public highway!. on the drag track i gave it much more than its ever got on the road.. and stu gave it more lol upto and including 8krpm he said.. hence the boost tailing off. i would expect yours to tail off some if you put it down the track.
The MBC is also wholly unreliable , through different gears holds different levels it has a mind of its own, in daily use and recorded runs.
i dare say a charge cooler might have had me a PSI or 2 more with the colder denser turbocharge, you know.. 10.3 psi thats easily beaten...
Sponge Bob
12-10-2007, 00:14
Would an electronic boost controller be better at holding boost perhaps?
weegaz22
12-10-2007, 00:35
it will spike less and hold boost at a set level....provided the turbo can provide the amount you have it set to, i get the different boost in different gears as well with my MBC
I've just flogged my AVC-R controller because it was no better than my ball-spring valve... maybe my valve's uncomonly good but it regulates boost perfectly. As stated, the extra features with an electronic controller allow you to reduce boost in certain gears/revs etc :eh: I prefer max boost all the time :twisted: just avoid booting it mid-corner lol
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