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Keith: (and others)
Per your request, here is my reply to Dave. I will forward his diagnosis
as well. Sorry to hear you are having the same symptoms, it's
frustrating.
Ed
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Message-ID: <37177034.6EAB@idt.net>
Date: Fri, 16 Apr 1999 13:15:32 -0400
From: Ed Van Scoy <edvs@idt.net>
Reply-To: edvs@idt.net
X-Mailer: Mozilla 3.01C-IDT-v5 (Win95; U)
MIME-Version: 1.0
To: Dave Dahlgren <dahlgren@uconect.net>
Subject: Re: Oiling Systems
References: <s716ed6e.052@sterlingdi.com> <37172A9B.512A3BBF@uconect.net>
<37173F95.2F7A@idt.net> <37177084.907C0E34@uconect.net>
Dave,
Oil temp:
I pre-heat the oil to 140 deg. then run the engine to operating temps in
the pits. Change plugs, then drag it out to the start line. As you know
the wait can be long. When I get close to "on deck" I run the motor to
at least 175 deg water temp (the elect fan kicks in then) and then shut
it off. On the start line I will run the engine at least a minute before
starting the run. I am generally pretty easy on the motor for the first
mile before laying into it. I do run Mobile 1 synthetic. I am taking oil
pressure readings from the stock location on the block. Where do you
suggest putting the sending unit? Oil pressure is well within the old
10lb/1000 rpm guage. Have tried several diff. oil pumps. The last one
giving up some pressure to volume.
Power:
It pulled just over 730 hp on the dyno (last time), all readings normal.
8500 redline, but usually runs 7600 rpms on the salt. After about 30 sec
of full-throttle down the course, oil pressure begins to fall. Cannot
simulate this on dyno, it just sits there and screams its lungs out with
no problems.
Clearences:
Don't have my "book" handy but it seems
Rod bearing .002
main .00250
skirt .0015
Bearing failues (oil starved) have all been at the front of the crank.
At last Speedweek, halfway thru the 4th mile I noticed the pressure
falling and killed it while it still showed 50 lbs. Aparrently the
damage was done as I tried to re-start while waiting for my crew and the
engine was seized.
I am in the process of converting to a dry sump, hoping this will solve
the problem. Would have done this earlier, but it never ran oil-starved
on the dyno. If you see anything else here that raises a red flag, let
me know.
Thanks for the input,
ED
Dave Dahlgren wrote:
>
> I think the first question I have is how hot is the oil. Most cars I see
> out there do not warm the oil up properly to begin with. Oil has to be
> 175 or more just to lubricate correctly. If you use the old run the
> bearings loose and the oil will get there stuff you will just have one
> failure after another. If this is a Chevy take the oil pressure reading
> off the front of the engine not the rear. The front is the pressure that
> is left after all the little'leaks' you might find it rather low.
> Pressure ought to be 10 psi /1000 rpm and never less than 55 with HOT
> oil.how much power does you engine make is real important also if it is
> 500 hp then most anything will workas long as the oil is hot and the
> clearances are right. If you have over 750 and a wet sump the what ever
> happens just will.Kind of need the dry sump after that. Let me know what
> the clearances are mains/rods/side clearance and end play on crank sort
> of have to start there. All the Winston cup engines and other stuff I
> have worked on all stays alive forever. We run the Cosworth 2Liter over
> 10000 rpm for the entire long course and never have a second of trouble.
> The bearings come out looking like new... Run 85 PSI HOT OIL Mobil
> Synthetic 20-50(woops a little 'speed secret'). Made a oil heater using
> engine water. We leave with 160 oil and get that in just a few minutes
> of warm up. I know you might say that this Cosworth is just a little pea
> shooter but on the nitrous it does make 450 HP at 4200 ft...Your engine
> is 3 times as big.
> The other thing you said is they fail how what is the failure and what
> bearings failed ??
>
> Regards
> Dave Dahlgren
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