p6 compression ???

This forum is about the Fordson F, N and E27N Major.
Post Reply
scoobyjim
True Blue
Posts: 173
Joined: Sun Mar 31, 2013 5:38 pm

p6 compression ???

Post by scoobyjim »

Is 250psi correct?

Emiel
True Blue
Posts: 488
Joined: Wed Apr 16, 2008 3:22 pm
Location: Netherlands

Re: p6 compression ???

Post by Emiel »

Hi,

Although I'm not familiar with the p6 engine I suppose 250 psi is far to less. Is approx 17 bar. A sound diesel should be round 25.

Try to find out where your compression goes away. Leaking valves is not a too difficult job and cures a lot sometimes.

Rgds Emiel
Best regards

Emiel

N 1937, E27N 1948, 8N 1948, E27N 1950, E1ADKN PP 1956, Dexta 1959, NH Clayson M103 1964

BarryM
Site Expert Team
Site Expert Team
Posts: 198
Joined: Thu Apr 17, 2008 12:11 am
Location: Australia

Re: p6 compression ???

Post by BarryM »

Compression:- 380 to 450 lbs. sq. in. Variation not more than 15 lbs. sq. in. Compression of 350 is satisfactory providing variation is within range.
BarryM

scoobyjim
True Blue
Posts: 173
Joined: Sun Mar 31, 2013 5:38 pm

Re: p6 compression ???

Post by scoobyjim »

What happened to compression ratio x atmospheric pressure= compression. Which works out at 238 psi .

oehrick
Site Governance Team
Site Governance Team
Posts: 1236
Joined: Wed Jan 29, 2014 2:41 am
Location: Norfolk Broads UK

Re: p6 compression ???

Post by oehrick »

I'd not thought of it that way before scoobyjim, but having riffled up the compression ratio for the E1a engine at 16:1, have second checked it as correct, (if you disregard the fact that the starting pressure will inevitably be somewhat lower than 1 atmosphere). According to the P6 handbook linked below the P6 is 16.5:1 so around 245 psi

To counterbalance that, the inertia in most mechanical pressure gauges may cause them to over read peak pressure, unless oil damped, in which case it may underread :scratchhead:


http://www.fordsonmajor.se/pdf/perkp.pdf may not help much but if you google I'll bet there is a manual for the P6 somewhere.

Happy hunting
Best regards
Rick - Bogside on Bure


1958 Diesel E1A Mk2 s/n 1470165 - still in working clothes

scoobyjim
True Blue
Posts: 173
Joined: Sun Mar 31, 2013 5:38 pm

Re: p6 compression ???

Post by scoobyjim »

Got the manual but there is no mention of compression.

oehrick
Site Governance Team
Site Governance Team
Posts: 1236
Joined: Wed Jan 29, 2014 2:41 am
Location: Norfolk Broads UK

Re: p6 compression ???

Post by oehrick »

Page 39, settings & data, 6th line down - I assumed those items common to P3, 4, 6 are the lines with a single entry ??
Best regards
Rick - Bogside on Bure


1958 Diesel E1A Mk2 s/n 1470165 - still in working clothes

scoobyjim
True Blue
Posts: 173
Joined: Sun Mar 31, 2013 5:38 pm

Re: p6 compression ???

Post by scoobyjim »

Yes so using the 16.5:1 all we can do is the formula mentioned above which =250

oehrick
Site Governance Team
Site Governance Team
Posts: 1236
Joined: Wed Jan 29, 2014 2:41 am
Location: Norfolk Broads UK

Re: p6 compression ???

Post by oehrick »

We're missing something important like pressure rise due to the compression increasing temperature (Boyles Law / Charles Law ? :scratchhead:) assuming test gauge is in the injector port there's no pump / injector influence responsible.

With the reduction in volume there is a temperature rise which just using the compression ratio doesn't factor in, as that assumes constant temperature

C'mon Emiel & Barry, put us out of our misery please, are we looking in the right direction, is there a constant or fudge factor which can be applied to the Comp Ratio to calculate the sort of peak pressures that will give an ignition temperature* or are you using figures based on practical experience of this sort of engine ?

*Can't find a pressure value but ignition temp seems to be about 480-500K or 207-227C
Best regards
Rick - Bogside on Bure


1958 Diesel E1A Mk2 s/n 1470165 - still in working clothes

Post Reply