Lotus Esprit with low compression

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Re: Lotus Esprit with low compression

Postby Alan » Fri Mar 11, 2011 4:39 pm

Hi,

Found the timing specs

All cams are symmetrical opening / closing
Open duration 252 degrees at crankshaft
Inlet maximum opening point 110 degrees ATDC
Exhaust maximum opening point 100 degrees BTDC

Will post some more waveforms later.

Alan
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Re: Lotus Esprit with low compression

Postby mrblonde » Fri Mar 11, 2011 9:57 pm

cool thanks Alan i had closer look at cranking waveforms the lower compression cylinder has some uneveness in comp tower rise and fall compared to good cylinder?
i will post tomorrow they are on my other computer thanks
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Re: Lotus Esprit with low compression

Postby mrblonde » Sun Mar 13, 2011 7:08 pm

hello again thought i would post some of the things that looked odd to my eye?
had a try? at working out max opening i get different results trying my eye from 94 to 102
from figures given should i be looking at around ivo 16* ivc 58* and evo 27 and evc 44 that would make 16+180+58/2-16=111 and ex around 98 max testing & measuring this way is new to me so please bear with me ,from what i work out intake cam is out? first impressions viewin waves i thought timing issue no defined intake ramp among other things, but its not the kind of car we get at our garage everyday so im probably wrong? ta for looking.
cams pico.jpg
Attachments
pico cyl4.gif
cams pico.jpg2.jpg
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Re: Lotus Esprit with low compression

Postby mapengo » Mon Mar 14, 2011 9:15 pm

I grabbed 10 minutes today and using Rod Mahers compression waveform viewer came to roughly the same conclusion,

The valve opening durations and times are not as specified on the intake but neither are the exhaust.

There is also fairly significant differences between the pressures and exhaust plateau on 3 & 4

Can we have a manifold vacuum check using the WPS plotted against cylinder 3 compression with WPS vs CKP vs an ignition event on another cylinder? Maybe 2sec/div at 2MS sample rate, idle, WOT then back to idle?

Even at this point, a mechanical check of the valve train condition would be warranted in my opinion but as we're having fun, let's continue with the scoping :)

Cheers

Doc...

Image
Last edited by mapengo on Tue Mar 15, 2011 3:55 pm, edited 1 time in total.
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Re: Lotus Esprit with low compression

Postby mrblonde » Tue Mar 15, 2011 11:57 am

hi i had another go at checking as Doc says hard to see evo and ivc clearly redid maths and had better results can we have those other waves please and and a wee peek at 1 or 2 cyl.
ta much
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Re: Lotus Esprit with low compression

Postby Alan » Tue Mar 15, 2011 4:00 pm

Thanks for the suggestions - sorry to keep you in suspense but I will not be back in the office until Friday so will do the tests then. Its turned into more of a mystery than we expected!

Alan
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Re: Lotus Esprit with low compression

Postby crackerclicker » Wed Mar 16, 2011 12:19 am

what is the actual complaint?
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Re: Lotus Esprit with low compression

Postby Alan » Wed Mar 16, 2011 7:55 pm

crackerclicker wrote:what is the actual complaint?


Its listed in the first post - its a bit odd as there are no symptoms at all but during testing of our software we found one cylinder had poor compression.

As above it will be Friday or Monday before we can perform more tests.
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Re: Lotus Esprit with low compression

Postby Alan » Fri Mar 18, 2011 5:11 pm

mrblonde wrote:hi i had another go at checking as Doc says hard to see evo and ivc clearly redid maths and had better results can we have those other waves please and and a wee peek at 1 or 2 cyl.
ta much


We did a capture of running compression on 1 and 2. I tried to upload them but have hit a limit on waveform upload size (its a new forum so there are still a few teething troubles). Anyway waveforms from cylinders 1,2 and 3 look identical. In fact the valve timing and compression looks similar across all cylinders.

The most obvious differences are both on cylinder 4 namely, low cranking compression and exhaust part of the running compression waveform at idle. For comparison:

Cylinder 3 (1 and 2 look the same, including valve timing)
running compression cylinder 3.gif



Cylinder 4
running compression cylinder 4.gif

Note the oscillations in the pressure and the rise in pressure. Cylinders 1,2 and 3 only get close to 0 psi towards the end of the exhaust stroke. Cylinder 4 gets there much sooner. Perhaps the exhaust valve is not opening fully / bouncing?

Will try to get the other waveforms that have been requested soon.
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Re: Lotus Esprit with low compression

Postby mrblonde » Fri Mar 18, 2011 11:14 pm

Hello again Alan thanks that makes sence of my findings,assuming im right? lotus.net has lots of info.
should we concentrate on cranking waves first? that compression loss should show somewhere? and would expect you have access to a few transducers? cover all possible areas of leaks. look forward to more ta..
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