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Location:
Brisbane
Registered:
February 2003
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what would make turbo manifold run red hot? leanout? very-rich?
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Mon, 12 April 2004 15:58
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sorry if this long winded...
on the way to Dubbo, the RA40 turbo manifold and turbine housing got extremely red hot - scared the crap out of all of us...
prior to this on the day, wilbo & i had been driving/flogging the car all over brisbane yet, several gawks under the bonnet did not result in a "holy shit! it's bloody glowing red hot!" moment (like we got at Warwick at about 10pm)
The smoke we got when pulling up was oil dripping from a split in the turbo drain onto the wastegate - but the evil glowing manifold (pics of that to come soon) was a shocker!
but... when i got the car home and started pulling stuff off it tonight - i find heavy carbon/soot eveywhere in the exhaust side of things - as if driving onto/off the trailer was going to coat everthing with enuf black to paint a house?
I can't check the carbi and i don't really know much about Strombergs CD's (apart from some triumph stuff i found on the 'net) but i was expecting stuff like:
-hard, light-coloured residue (like on exhaust when you do highway drive)
-burnt-out turbo gaskets
-melted/stuffed turbine blades
-stuffed turbo bearing
but i got none of that...
instead i got:
-the gaskets on the turbo (in & out exhaust) were not leaking
-the bearing in turbo seems to have same play as per 2 weeks ago
-the exhaust turbines has no visible damage (e.g. no sagging or missing bits)
-the intake turbine is clean (e.g. front seal intact) and has no debris
-the smoke came from oil on the waste-gate and it had carbon 'stain' like you get from sooty candle flame so i think we were lucky not to have engine fire
-the oil-drain hose (heavy duty black hydraulic hose) had split below turbo which is why wastegate is oil-soaked
- the inlet side flange of wastegate had minor leak so most of the noise must be from the buggered manifold gasket.
-the exhaust manifold/turbine/dump pipe is internally coated with carbon/soot so the short run it got to get on/off trailer while running non-boost with heavy choke must have coated everything, because even the plugs are black
- the manifold is stuffed because when you squeeze the wrap, you can hear it crunch - so a lot of the manifold has turned to ferrous-oxide or similar
i'm going to go EFI and am thinking of sourcing a smaller turbo - CT20 or CT26 or T28 (so i can stick to 10-14psi as an upper limit) - as i think this T04 is way too big for a low-rpm engine ... and dumping the steam-pipe log manifold for a h/duty but narrower pipe manifold with the turbo mounted outside cyl's 2 & 3
here's the pic's so far... but any thoughts on whether:
a dodgy carbi could make all this steel go red hot
a short run with lots of choke would carbon up the entire manifold
the oversized turbo (T04) would have contributed to under-fueling.
pics are here:
http://members.optushome.com.au/mkhala/red_celica/ pdfs/RA40-april%2004-part1/RA40-april%2004-part1.h tml
(there's a CT20 in the pics for comparison)
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Location:
Melbourne
Registered:
June 2003
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Mon, 12 April 2004 16:34
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but isnt it normal for turbo manifolds to glow when theyve been pushed. my mates 626 manifold always glows when he gives it a good run in constant boost, a guy at a performance place told him thats normal when turbos glow if theyve been pushed.
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Location:
Brisbane
Registered:
May 2002
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Mon, 12 April 2004 22:39
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Yeah you would expect the manifold to glow when pushed, but on highway driving? The thing was that it wasn't doing it when it was being driven around the city (and we were getting fair up it really around the city  ).
I was expecting to see burnt exhaust valves and what not charles...no sign of them?
The only thing I can think is that it is running rich at idle (and we idled it down to let it cool, hence the carbon build up?) but mega lean up top 
Back to it not doing it in the city might also be related to extended running while lean (if it is running lean only up top, right at the highway cruising rpm/load).
Hope you can figure out some answers bud! (I'll send you the crappy vid and that pic now too btw, also I've got my new diff in, will start dropping the box today  )
Cheers
Wilbo
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Location:
Perth
Registered:
October 2003
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Mon, 12 April 2004 23:27
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Have you noticed a power loss?
Perhaps your ignition timing is very retarded?
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Location:
Brisbane
Registered:
February 2003
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Tue, 13 April 2004 02:00
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| Skip wrote on Tue, 13 April 2004 09:27 |
Have you noticed a power loss?
Perhaps your ignition timing is very retarded?
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thanks skip, i forgot about this stuff:
-surging/faltering over 7-8psi boost suggesting not enuf fuel
-vacuum at idle around 15-18mm/Hg - not enuf i think
-i had reset timing back to about 12degree static before driving around brisbane with wilbo, it had been running very high and was prone to pinging
- there was less power at low revs (reduced timing?) but the turbo seemed to be spooling up onto boost very nicely from about 2750prpm
- compared to when i had massive leak in exhaust manifold, it spooled up quicker - as if there was less restriction on incoming air and less exhaust gasses escaping before turbo - and it required less pedal movement to get the thing up onto boost (e.g. prior to this, spooling up took longer)
- we weren't experiencing any pinging/detonation - which the previous timing was causing
- in attempt to get it running cooler, we pulling the timing right back and ran with choke on - this hopefully explains all the soot/carbon.
- the manifold is steam pipe, not exhaust tubing - so i figure it needs a shitload of heat to get glowing red hot?
tho more i dwell on this, the more it sounds like carbi not delivering enuf fuel at high rates of air flow - tis the only thing that explains why it was red hot at cruise, yet sooty from idling.
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Location:
South Australia
Registered:
July 2002
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Tue, 13 April 2004 02:52
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Sounds like it's leaning out further up the rev range, doing a carby/turbo set-up is a huge fiddle so you probably could get this *mostly* tuned out, but you'd more than likely need to drop the boost to 8psi just so that you don't have so many tuning problems.
EFI is always easier (although generally not cheaper) to use for a turbo *petrol* engine.
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Location:
Perth
Registered:
October 2003
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Tue, 13 April 2004 04:58
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The timing in my car was retarded about 10 - 15 degrees than where it should have been, this was causing my exhaust housings and exhaust manifolds to glow bright red, clearly visible in the day. The car was real sluggish but made boost real quick, but when the boot was mashed it could not use all this boost, causing me to make more than 15 psi boost, which is what my haltech wastegate map controls to. The car was also running hotter, if this sounds like any of your problems maybe you should check the timing again. Exhaust note was noticeably different too.
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Registered:
June 2002
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Tue, 13 April 2004 09:05
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Sorry but a bit OT.
Skip: did you get it retuned since your 187rwkw episode?? If so any more RWKW's??
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I Supported Toymods
Location:
Sydney
Registered:
December 2002
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Tue, 13 April 2004 09:16
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My exhaust housing was getting really hot when then gasket was stuffed...
Also
-Boost wasn't as high as usual
-used more fuel
-didn't idle properly
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Location:
Perth
Registered:
October 2003
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Re: what would make turbo manifold run red hot? leanout? very-rich?
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Tue, 13 April 2004 09:21
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No not yet, I still need to take it to get a retune, someone else this time. I cant for the minute cause i fried my clutch at the drags and need to replace it, and im still deciding whether or not to put the bigger 440cc injectors in.
My numbers at the drags related more to a rwhp of 280 not 256 using an et formula, those formulas are for a normal sedan not the aerodynamics of a brick, and for a perfect clutch, not a badly slipping one like mine, so perhaps my injectors maxed out after all as the tuner suggested, relating my rwkw back to a supra or soarer perhaps i have around 220 - 230rwkw, dont know 
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Location:
Brisbane
Registered:
February 2003
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