Simon
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 posted on 12/10/08 at 06:19 PM |
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Suggestions for my probs please
Chaps,
Finally got the car on the road today, after getting lights and sump guard back on.
First, and major (poss) prob is oil pressure. When I'm doing sensible revs like over (at a guess) 2500 I'm getting 35+psi. When I'm
doing just over tickover (like at 30 ish), I'm getting about 3psi (yes, three).
Now I know the arguments for the low pressure, high volume, but that seems a bit low.
Other prob (which Dave Walker found) is that, if I accelerate hard, all goes well till I get boost, then it cuts out, but carries on as normal as soon
as boost is off.
Final prob is tickover is too high and DW couldn't get it down, suspecting an air leak.
If I block ends of inlet and exhaust and attach a compressor line, I should find he prob, if any.
Pics of setup are on my blog, but the fuel pressure regulator is in the boot (as suggested on here (and which worked for them, sort of thing) but
which DW wasn't impressed with.
Now, could the long run of the pressure line to reg be causing a massive delay in in increasing fuel pressure to match boost.
Any suggestions welcome.
It went quite well (to about 3000rpm) btw.
ATB
Simon
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Paul (Notts)
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| posted on 12/10/08 at 06:25 PM |
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Oil pressure- low revs giving no oil pressure but it building up as the revs increase sounds like the oil pressure release valve on the pump is stuck
open.
The above is only an educated guess..
Paul
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clairetoo
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| posted on 12/10/08 at 06:26 PM |
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As far as I am aware the fuel pressure regulator should be on the fuel rail , or at least as near to there as you can get it - after all , the only
place where the pressure actually matter's is at the injector's .
Its cuz I is blond , innit
Claire xx
Will weld for food......
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mark chandler
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| posted on 12/10/08 at 06:45 PM |
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Hello Simon
Low oil pressure on tickover is typical, if its not the pressure relief valve failing to fall back then its the pump. undo the 6 bolts and drop off
the pump bottom plate, if this is badly scored you can revieve with a piece of glass and wet and dry paper, just sand it until the scores are removed.
Unfortunately if its leaking by the shaft you will need a need front cover, Do not get a P38 one as the sump is a different shape.
As for fuel pressure valve in the boot, its unusual but although may introduce a slight additional delay (in mSec) I cannot see why its really
affecting things, but best placed at the end of the fuel rail next to the vacumn takeoff.
Have you got a turbo regulator fitted ?
Regards Mark
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rusty nuts
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| posted on 12/10/08 at 06:45 PM |
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If you think about it logically with the regulator in the boot you have to increase the pressure in the fuel feed , fuel rail AND return which will
cause a slight delay in increasing the pressure at the injectors. As far as oil pressure is concerned what oil are you using? I used some cheap oil
when I rebuilt my xflow and the oil pressure at idle when hot was not brilliant , in fact I even fitted an oil cooler and stat . Changed the oil after
about 500 miles and put in some decent stuff which improved things no end. The Rover lump originally used 20/50 IIRC . Did DW managed to map the
ignition at all? Over advanced timing will cause a high idle . Are your throttle butterflies closing properly? , could be off center or sticking?.
When searching for air leaks try squirting WD 40 around manifold , throttle housing etc. Engine revs will rise even higher if WD40 gets into intake
system
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Volvorsport
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| posted on 12/10/08 at 06:49 PM |
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yeah , should be on the fuel rail .
oil pressure should rise as engine revs , sounds like yours does , 2 bar oil pressure is ok , maybe a littlte low
what does the manual recomend ?
www.dbsmotorsport.co.uk
getting dirty under a bus
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MikeRJ
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| posted on 12/10/08 at 07:02 PM |
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30 PSI at 2400 RPM is the correct pressure for an RV8, at least the older ones. They are notorious for low oil pressure at idle, and having to supply
two turbos won't be helping things. That said 3 PSI does seem very low indeed, has the engine ever had a new oil pump/bearings?
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mark chandler
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| posted on 12/10/08 at 08:18 PM |
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Think Mike may have got the cause, have you got restrictors in the turbo feed, couple of old carb jets maybe?
You used to be able to get extra high volumn pumps a few years ago, a deeper pump vanes, long bolts and spacer.
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tootall
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| posted on 12/10/08 at 09:36 PM |
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yer mike sounds like he hit the nail on head restricting oil to turbos int good unless its a roler bearing turbo where it needs restricting is
probably the case of the turbos heating the oil and its just getting to hot. whats the pressur at idle when its cold ??
some people dream of sucsess, others just get on and do it !!
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Simon
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| posted on 12/10/08 at 11:38 PM |
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Thanks for all the replies Peeps
First off, I'd wondered about the oil pressure relief valve, but I can't be sure it wasn't doing it at Emerald's - I was too
busy watching water temp!
I'll pull off the cover and check the check inside, and clean up the relief valve, though I suspect the real cause may be the lack of
restriction in the oil feed pipes - one of the things happening at higher rpm/boost (well, 2psi) was smoke from the o/s exhaust, which DW suggested
may be the oil drains (and I'm a bit suspect of that particular drain); but if too much oil is going through then...
Ok, so I need to restrict the oil to the turbos, but how much? I'd have thought they'd be quite "oil hungry". Feeds are 10mm
copper pipe, could always squish a bit? Crude but effective.
I think the high flow oil feeds were for the P6 motors which weren't as deep (as SD1 and later pumps), though I stand to be corrected.
As far as I know pump is original.
Re the fuel thing. There is basically a complete high/low pressure circuit by the tank with the high pressure off to the fuel rail. There is a
pressure tube from plenum to regulator, but I think I may just do it properly anyway. DW wasn't impressed
Rusty, he managed to map it up to about 3 - 3500 rpm, but he said something was wrong, but he didn't know what. Beyond the 3500, he's sort
of mapped it, but only using guesswork (which I suppose is the sort of guesswork Kirk would get from Spock)
Thanks again
ATB
Simon
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MikeRJ
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| posted on 13/10/08 at 09:25 AM |
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You shouldn't really use oil feed restrictors if you have plain bearing turbos (e.g. Garrett 'T' series), since the restriction
should be provided by the drillings within the turbo 'core'.
Roller bearing turbos (e.g. Garrett "GT" series" do need oil feed restrictors.
One very common cause of low oil pressure on the RV8 is excessive wear on the rocker shafts. If you remove/replace the pump then make sure you pack
it with Vaseline when you refit it or it will never prime.
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