2 1/4 ltr diesel

thats the point that I was after.

Heres exactly what I was aiming at.

if you advance the timing too much when the fuel is injected it will ignite, like its supposed to BUT the piston will still be rising as the pressure increases. Get it early enough and you can wind up with the piston trying to go backwards.

The injection timing is advanced before top dead center because it takes time for the combustion process to initiate, develop the flame front, raise the pressure in the precombustion chamber and then eject the remaining fuel/air from the precombustion chamber where it can do its work inside the cylinder.

Roughly Its all about peak cylinder temps and pressures (Peak combustion temperature) pressures. IF you hit peak pressure after TDC youve wasted some potential power because the fuel air mix is being ignited late in the cycle and may not burn completely. Hit peak Pressure at TDC and your making the best use of the fuel available by making it burn as hotly as it can for as long as it can.

If you hit peak pressure before TDC the engine will want to try to run backwards, if the energy in the crank and flywheel is sufficient it will lift the piston up over TDC and then it will come back down under power. This is more or less diesel knock. ITs like petrol knock but a lot of times worse. This problem is exaggerated in a precombustion diesel engine and espscially ones like the 2.25.

The pre combustion chamber is peened into the head. If you put in too much fuel or put the fuel in too early more of the combustion takes place inside the precombustion chamber raising the pressure and the temperature. While this isnt a problem while the piston is still coming up when it starts to go down things get more annoying. With the pressure change as the piston starts its power stroke the fuel air charge can do some expanding due to the lowering pressure on the piston side of the precombustion "plug" at 2000 Rpm theres 1000 pressure cycles like this per minute per chamber.

With that given...

How many impacts does your average rattle gun make per minute?

What do most people use to free up a nut that a rattle gun alone cant shift? (no, Im not talking about wd40 or inox)

Heat, of course. So the combination of heat and repeated knocking can free the precombustion chamber out of the block.
Thanks for the explanation.

That being said, was the 2.25 diesel engine an engine that was right on its limit regarding performance? Surely there must be some reasonable ways to get an improvement without dicing with death.

In the Series3 SWB on military 2a chassis I'm putting together (see here): http://www.aulro.com/afvb/remlr-proj...8-chassis.html

I intend to use the 1982 diesel engine from this vehicle:
http://www.aulro.com/afvb/series-3/8...ml#post1055858

give it an electric fan to reduce some of the work load, maybe change the air filter and possibly extractors. I am trying to learn what I can about pump mods. I'm still a novice and don't want to regret putting a diesel in when I have a petrol sitting there ready to put in too.

yes, there are some gains to be made, and made safely, the purpose of this exercise is to expose you to some of the things that you may not have considered.

lets go back to engine 101...

at the end of the day a diesel engine is just an air pump. I dont care how much fuel you stick in it or when you stick it in. If theres not enough O2 then the fuel wont burn it just goes out the exhaust. this is why they invented turbocharging, but thats new school stuff. Its an old school engine so lets think about old school tech.

have a look at cleaning up the air intake and the exhaust, Theres an absolute mile of room around the engine, making up a custom air intake and an exhaust isnt that hard and youve got plenty of room to work with, can you say tuned intake runners and extractors?

If at any time with a NA diesel engine you can get it to blow black smoke you have too much fuel and not enough air.

I like to think the development of the 2.25 diesel went along these lines.

Marketing:"hey R+D, the farmers reckon the 7:1 compression ratios a bit light how much compression can we make the block handle without retooling"

R+D: "Hi marketing, uhhhhmmmmm"

weeeeeks later

Engineering: "HI marketing R+D have had a brainfart they've shown us and we made the engine do 20:1 but we cant retard the spark enough to stop it from pinging"

Marketing "huh? can you use words that sound like we can make money? we'll talk to R+D"

later in the conversation

R+D: "well no 20:1 is a touch high for petrol"

marketing: "so we have to retool"

R+D: "nahh just go buy some diesel in jectors ,whack em in the spark plug holes and drop an injector pump into the hole where the dizzy was"



as far as engines go, the 2.25 Diesel makes an unkillable platform to build a petrol on

Ok, I know this is going into the theoretical and $$$$ territory here...but a thought or two or modifying the diesel:

1 - having a cam ground so that the exhaust and inlet ports stayed open for a little longer = more air in, and longer exhausting cycle = less exhaust in the cylinder when air is introduced, plus a little extra fuel - possibly a little more power? But would perhaps also mean:

2 - modifying the head for longer valve stroke and/or springs.

Not sure how much room there is to tamper 'up top' but a thought....? would I be right in saying that this may give the diesel a little more legs higher in the rev range but may loose a little torque down low?

as far as engines go, the 2.25 Diesel makes an unkillable platform to build a petrol on

I've often thought about slapping a petrol head on the block of a diesel, with a diesel crank, pistons and conrods. Indestructible indeed!

Quote:

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Originally Posted by Veryan

..........
as far as engines go, the 2.25 Diesel makes an unkillable platform to build a petrol on

I've often thought about slapping a petrol head on the block of a diesel, with a diesel crank, pistons and conrods. Indestructible indeed!

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I think you are a little late for that - Rover did this over fifty years ago.

John

Quote:

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Originally Posted by Blknight.aus

..........
I like to think the development of the 2.25 diesel went along these lines.

Marketing:"hey R+D, the farmers reckon the 7:1 compression ratios a bit light how much compression can we make the block handle without retooling"

R+D: "Hi marketing, uhhhhmmmmm"

weeeeeks later

Engineering: "HI marketing R+D have had a brainfart they've shown us and we made the engine do 20:1 but we cant retard the spark enough to stop it from pinging"

Marketing "huh? can you use words that sound like we can make money? we'll talk to R+D"

later in the conversation

R+D: "well no 20:1 is a touch high for petrol"

marketing: "so we have to retool"

R+D: "nahh just go buy some diesel in jectors ,whack em in the spark plug holes and drop an injector pump into the hole where the dizzy was"



as far as engines go, the 2.25 Diesel makes an unkillable platform to build a petrol on

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Actually, as I suspect you know, the diesel (admittedly only 2l) preceded the petrol engine by several years. The 2.25 diesel using the same block as the petrol engine needed some improvements in manufacturing methods for the crankshaft, and it also had some minor changes to the head, I think to reduce the knock by improving combustion.

John

yep...

but I also know when they got the 2.25d sorted the same basic design elements lasted all the way into the td5.



one of the poopsngiggles experiments I was going to do when the replacement 2.25 turns up for fozzy was to deconvert the existing diesel into a petrol as a time laspe video and post it up.

What I would do you your specific situation is this. Install the diesel, spend some time tweaking the setup (extractors, air intake and pump tune)and if you dont like it swap the head, dizzy, lift pump and manifolds onto the diesel and make it a petrol.

After extractors the best (read cost effective) mod you can do to the 2.25p is install the cam from a diesel.

What impact does the diesel cam have on the petrol engine? (in terms of power vs torque)

Im rebuilding a 2.25P at the moment and would consider the diesel cam if its worthwhile.

Off the top of my head (I dont have a spec sheet for both on hand)

it opens the valves earlier, a touch more agressively and has a bit more overlap.
If everything else isnt just so, you can get some hesitation issues at small throttle openings but when you've got it all opened up it gives you more torque down the bottom end and might steal a bit from the top.

I wouldnt do it if you didnt already have the rest of the breathing sorted out unless you needed to replace the cam for some other reason or had the engine apart for rebuild.

Quote:

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Originally Posted by Blknight.aus

yep...

but I also know when they got the 2.25d sorted the same basic design elements lasted all the way into the td5.



one of the poopsngiggles experiments I was going to do when the replacement 2.25 turns up for fozzy was to deconvert the existing diesel into a petrol as a time laspe video and post it up.

What I would do you your specific situation is this. Install the diesel, spend some time tweaking the setup (extractors, air intake and pump tune)and if you dont like it swap the head, dizzy, lift pump and manifolds onto the diesel and make it a petrol.

After extractors the best (read cost effective) mod you can do to the 2.25p is install the cam from a diesel.

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I assume you're saying that to me.

Sounds like it could be a go-er!

Have you seen anyone's custom intakes and extractors? Any novel ideas?

I was reading that some military vehicles use snorkels all the time as the air intake. Gets it up out of the dust. Does a longer intake pipe decrease effectiveness, and is there an intake diameter size above which provides no additional benefit?