Just curious about Gasoline to Diesel conversions. 1

[TZSiR]

I've seen one in person, but at the time I wasn't interested enough to check it out.
I'm curious is to if anyne has any experience with this? If so was it done with the stock components or did it require extensive modifications? Basically I'm looking to convert a port injection engine into a diresct injection, but I have no idea where to even begin looking for this info... Yes I'm aware of the problems that occur from high sulfur contents of pump-gas. That's why I plan on running something like an alcohol.

 

[shbazjinkens]

I've been under the impression that Diesel engines are manufactured to closer tolerances and with thicker cylinder walls to account for the higher compression ratios, which is what makes them so much more expensive than gasoline engines. I'd imagine that racing engines are the same.

 

[1Bluegrass]

I don't know if it is relevent to the thread but for what it's worth we run a 351 cu/in v8 on straight alky thru a carb and 11 to 1 cr.
A sprint car racing class runs alky 410 cu/in engines on fuel injection in the intake feed tubes as well as injectors direct into the chambers.
In our case we make in excess of 500 hp with carburation and the FI cars are all above 800 hp. The FI 410s are well above 11 to 1 cr.
None of this comes even close to being a diesel type operation.
There are a nunber of different types of engine configurations for diesel use. All have high compression ratios.
I am most familuar with the old GM 4/71 and 6/71 industrial engines. These had blowers that forced air into the cylinders when the piston uncovered ports around the cylinder then exhausted out a standard valve like a gas engine.

 

[Nothegger]

Injectors direct into the chambers? You mean they are direct injected? Thats interesting, how did you do that, I've seen various solutions like modifiying heads, injection through spark plug hole etc.

I planned to run this engine with as close tolerance parts as I can get, just the cylinder wall's are pretty thin. I was thinking about some liners or sleeves...

 

[patprimmer]

As far as I know, sprint cars use "down nozzles" in the port or manifold near the port. They are shaped so as to be quite close to the inlet valve, and inject directly onto the back of the valve.

Regards
pat pprimmer@acay.com.au
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[1Bluegrass]

They do use both injections at the same time.

 

[icrman]

It would be no problem building up something like a 350 sbc engine with the required compression ratio to run on diesel. 14 or 16 to 1 will do it. And there are many of those engines with that ratio running races. The angle of the injector would be a problem with a DI system. And it would be an unknown how long the structure would take the higher peak pressures of diesel operation. Unlike the standard gasoline engine the naturaly aspirated diesel engine has close to atmospheric inlet pressure most all the time, except of course considering highspeed flow restrictions. I think all will agree it would work. But for how long?

 

[evelrod]

icrman, based on my experience with my neighbors GMC PU with the Olds type diesel engine (late 70's, I think) I would venture that ~80,000 miles would be about the limit. My bosses Oldsmobile diesel only made it beyond that because it had constant and continuous maintenance. We towed it in, uuummm, maybe once a MONTH!!!! Hey, he was the boss and who was to argue with him? (That may be a SLIGHT ;-) exageration).

Rod

 

[swall]

I recall seeing a "reconversion" kit for those Olds gas to diesel engines 5 or 6 years ago.Yes, you could convert it "back" to gas.

 

[bobqzzi04]

Rob45

Actually the Rabbit diesel was a excellent diesel engine for the vintage, and has developed over the years (using the same basic design and architecture) into the current TDI which is probably the nicest automobile diesel in the world. The original ones were certainly not powerful, but they were reliable if maintained properly. They virtually never had bottom end problems- the block crank and rods were more than up to the task.

 

[evelrod]

"They vertually never had bottom end problems-the block crank and rods were more then up to the task".


Funny I saw an awful lot of broken cranks and bad bearings in the first incarnation of the Rabbit diesel in the U.S. It was quite common to convert them to the gasoline version at the time. If I remember correctly, the originals had the crank "snout" break off due to ???. The original engines were prone to overheat (I do not know the reason) and the cyl heads would crack. Any damage to the timing belt would result in a broken camshaft (and all that entails).
Granted the problems were solved---eventually. My son in law will have nothing to do with VW to this day, irrational as that may be. Some of the later Rabbits I have seen have accumulated some impressive mileage figures in spite of these original difficulties. At least VW , unlike some domestic auto makers of the era, did not give up on the engines and continued to fix them.
I agree the new engine is super. My son had a 6 speed diesel wagon in Europe for a spell---he ablolutely loved it.
Unfortunately, it's not imported to the U.S. !

Rod

 

[TOHCan]

Check the restricter plate engines in NASCAR running over 15:1 on gas (static, not effective). CART engines run alcohol but purge the fuel systems after.

 

[1Bluegrass]

Does anybody remember back in the 70s when you used to turn your engine off, take the key out and it magiclly turned into a diesel and still kept running as you walked away and into the house?

 

[icrman]

Run on, mostly caused by hot spots, and that would make it a glow plug or glow spot engine not a diesel. Gasoline needs way more than 16:1 to autoignite. Its a low cetane fuel.