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Discussion Starter #1
Has anyone had any problems converting the 4afe to diesel? I have a buddy Jack who is raising the compression to 19:1 so he can run on waste oil.
I told Jack I didn't think it would work so good but that isn't stopping him. I'm sure someone has done this, because of all the v-8 diesel conversions done in the 1980s.
He wants to drive for free.
 

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Vroom?
2003 Audi A4
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I didn't think it was possible to turn a gas engine into a diesel... the compression ratio's are nuts on diesels. Like the jetta I have is 30:1 I think it's something insane like that lol
 

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Better off to just ride a bike and grab a hold of bumpers...
Seriously, the diesel engines I have seen have many differences to make them work, too many for a practical conversion.
 

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He'd probably be better off trying to transplant a diesel engine from an older VW.
 

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Vroom?
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he's just better off buying an old vw, not just taking the engine. they don't have sparkplugs but you could probably fill those holes with the glow plugs diesels have. But you know I would think a diesels block would have thicker walls and so fourth. Because a diesel aluminum block that is smaller that the 4A block weighs more (I have a 1990 vw jetta, turbo diesel). you would need high compression pistons, if they made them for such a high compression for the 4afe engine. everything inside would have to be flawless because your clearences would have to be so close... just... not worth it lol. Buy the jetta. But even with the turbo they only have 63 hp. They are more roomy and have a larger trunk than the corolla's. Only car I've seen that is front wheel drive yet looks like it has the rear wheel drive trans, just because it's so long.
 

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Moving Forward
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not only the hight compression rates but the temperatures. Most diesels run at extremely high temps to facilitate the burning of the diesel fuel. THey have to have the high compression to get the heat built up where it needs to be. Just converting a gas engine to diesel is not going to be very cost effective. The entire fuel system will have to be replaced, the injectors will not work taht come with the Corolla because they do not operate at high enough pressures either. You will need some kind of injection pump to pressurize the fuel before it is injected into the cylinder. MOre than likely the bottom end of the engine is not going to hold up either. Those little 4A's were not meant to run at that high of compression and will do some pretty good damage probably.If you go with some kind of Electronicn diesel injection then you are going to have to have an ECU to control it. If you go with mechanical pump then you ahve to mount it somewhere nad then figure out some kind of chain or gear setup to run it off of the engine.

The list goes on and on as to what would probably need to be done to make it work.

As for diesel to gas conversions inthe 80's. most of those were people that tok the diesels engines out of their cars and then dropped a SBC in instead.
 

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Vroom?
2003 Audi A4
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fuel likes will have to be made of steel for diesel. My jetta doesn't have many rubber lines because of the presure everything has to be at. If that V8 thing is true, about converting to diesel. a 80's V8 block is alot more beefy than a 4afe engine, since weight didn't seem to be much of an issue back then for those cars and trucks.
I had completely forgot about the higher temp that diesel's run at, good point Cyorke :)
 

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Resident asshole
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Actually diesels run cooler than gasoline engines, Ever wonder why diesel cars suck during winter :lol:
Only way to convert a gasoline engine to diesel efficiently is to swap in a toyota 2C or 1C engine. Too much work for a 4A-FE to be converted.
 

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Vroom?
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Flashmn said:
Actually diesels run cooler than gasoline engines, Ever wonder why diesel cars suck during winter :lol:
Only way to convert a gasoline engine to diesel efficiently is to swap in a toyota 2C or 1C engine. Too much work for a 4A-FE to be converted.
they do run ALOT hotter than gas engine! They suck in the winter because their oil is so thick to begin with that when it gets cold it's more like a gel than anything and it makes it hard for the engine to crank. The fuel also does the same thing which is why you have to add conditioner after a certain temp otherwise forget starting the car.
After the car is started withing 10 min all the snow is melted on the hood and if you have the heater running all the snow is melted on most of the car too lol.
 

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they do run ALOT hotter than gas engine! They suck in the winter because their oil is so thick to begin with that when it gets cold it's more like a gel than anything and it makes it hard for the engine to crank.
No they actually dont, the exhaust gas temp is on average 200C cooler than a gasoline engine, they suck in winter time, because the temperature of the coolant doesnt reach that high of a temp. Fuel gelling problem isnt an issue, we have "winter grade" diesel in finland, which goes down to about -40C and light oil can be used such as gasoline cars.
 

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Flashmn said:
No they actually dont, the exhaust gas temp is on average 200C cooler than a gasoline engine, they suck in winter time, because the temperature of the coolant doesnt reach that high of a temp. Fuel gelling problem isnt an issue, we have "winter grade" diesel in finland, which goes down to about -40C and light oil can be used such as gasoline cars.

Yeah he's right exhaust temps on a diesel are almost half the gas engine temps. Lots of people i know have burnt out probes for diesels on their gas powered cars for the EGT gauge.
 

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Vroom?
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the diesel engine runs great after you get it started. it sucks in the winter because of the fuel and oil getting thicker. it's alot easier to ignigite something with a spark in the cold then it is with thick ass oil and trying to compress it. A block heater and some diesel conditioner will fix that problem.

now I am not sure whats up with this... but everything I have ever read about the diesel says it runs hotter than the gas engine. Fuel/air mixture will ignigite at 250 deg C, where as with a diesel that is what you want to do!
http://www.clubb5.com/b5beat/articles/00009_ckatkinson_what_heck_is_tdi.shtml

"a small quantity of fuel is injected to raise the trap temperature to as high as 1100°F, incinerating the soot in about 15 minutes, according to Gary Smith of General Motors Powertrain Division."
http://www.popularmechanics.com/automotive/auto_technology/1266891.html?page=3&c=y

doesn't take much to light gas fumes on fire. diesel on the other hand if you throw a lit match into a container of it the match will hit the diesel and go out :p

Now maybe the exaust temp is lower, not sure how but maybe. I have a diesel jetta and I am telling you it warms up faster than my corolla does! just saying that because flashmn said something about how the diesel engine running cooler makes them run shitty in the winter. The exaust manifold alone on my vw is at least twice the thickness of the 4af engine's. Maybe the newer tdi engines have lower exaust temp... but that might be because their exausts have more to go through. also make sure you are comparing engines of the same size.
 

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Everything on the diesel is thinker because of the violent explosion when the fuel combusts, anything that is that unstable when compressed is bad. Kinda like lograde nitro Gliserin. Kinda but not really. ;)
 

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Now maybe the exaust temp is lower, not sure how but maybe. I have a diesel jetta and I am telling you it warms up faster than my corolla does! just saying that because flashmn said something about how the diesel engine running cooler makes them run shitty in the winter.
My friends Diesel Vento has an electric heater element parallel to the heatercore, to make it "nicer" in winter time, however the gauge rarely goes even up to 90 on normal driving from what I've observed. I think the Jetta (american version of the vento) has the same heating element there.

Everything on the diesel is thinker because of the violent explosion when the fuel combusts, anything that is that unstable when compressed is bad. Kinda like lograde nitro Gliserin. Kinda but not really.
Its not that violent, anything volatile is gonna be unstable when you compress it, diesels just are made to ignite the fuel by heating the air up when you compress it and then spraying the diesel into the combustion chamber at the correct moment to ignite it, its still controlled operation, unlike detonation in gasoline engines. Mainly the reason is that you only compress the air, not diesel and air mixture.
 

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Vroom?
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but when you compress something that much it will generate an insane ammount of heat. Everything is thicker because of the high compression ratio. Even though they made the TDI lighter it's still heavier then a 4age.
Another thing you better tell your friend is that he will have to get special fuel lines for the car. IF you have ever knowticed that the diesels are steel and look like a mess it's because they are all the same length so every cylinder gets the same ammount of fuel
 

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but when you compress something that much it will generate an insane ammount of heat. Everything is thicker because of the high compression ratio. Even though they made the TDI lighter it's still heavier then a 4age.
Well, the TDI has a cast iron head IIRC, it adds quite alot of weight, 4A-GE isnt even that heavy, one man can haul it around.
Yeah, compressing air does give out heat, but its not as insane as you'd think, average diesel runs at a 22:1 compression ratio (some more some less, but lets say 22:1 average). Race engines CAN run 16:1 compression in gasoline engines, which is starting to be a critical CR, its the problem that the fuel is with the air that makes gasoline engines unable to run higher CR's. Lo and behold the Direct injection gasoline engines, which spray fuel directly to the combustion chamber. Those would theoretically be able to run CR's close to diesel engines. No problem and danger of detonation there.
Its the combustion process that actually heats the engine up, and since diesels have cooler exhaust temps, the combustion process is cooler too, so therefor diesels are worse in heating up aswell.
I'm not sure if diesels have equal length lines to the injector, dont have enough experience, but if they do its not the amount that is done by that (thats done by the feed pump, because diesels accelerate and decelerate with change in feed amount), but it would be because the injection has to be timed correctly, and then equal length lines would give same timing to all cylinders.
 

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Vroom?
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my jetta's injector pump runs off the timing belt. Even the new big diesels have the equal length lights. IT looks like a mess of steel hose.
RACING engines are also meant just for racing. They tend not to last that long. Diesel engines will reach 500 k if you drive it long distances on a regular bases. Most will do more. It's just the body of the cars that tend not to last. your lookin at a stock engine from the factory not something that people have put tonns of money into so it can last just a few races.
Gas engines won't have that kind of compression ratio for the same price.
and you sure they have a cast iron head? my 1990 one has an aluminum block and the head looks aluminum too. What they did with the tdi is hollow sections out that didn't need to have the strenth there to lighten the engine up a little. For christ sake out 2001 windstar is easier to push than my jetta, and thats a minivan!
 

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Discussion Starter #19
Its Alive!

O.K. now Jack is a smart guy; but I thought he had lost it when he did this diesel coversion on his a-fe motor. Mounting a vw injection pump to run off a longer timing belt was a hassle but he did it. Making custom piston compression caps with valve clearance was a challenge but he is smart.
He left the spark plugs in so he could contol the moment of firing and use them a sort of a glow plug.
Man! I have never heard such a racket in all my life! It sound like a rod knock on ever cylinder. But it works!!?? For now. Smokey, clattery & slow.
I don't think it will last for long but the car didn't cost him anything.
 
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