Has anyone done the Math on this ?

How much cooling do you think you are getting?

How much extra oxygen would that amount of cooling put into the cylinder?

If the fuel is calibrated properly for that amount of air entering the cylinder how much more hp/torque would that produce?

Is there a down side to extra cooling of an engine which uses the heat from compression as its source of ignition ?

Even in the MB diesels.. there is a difference in the compression ratio between the turbocharged engines and the normally aspirated.....At what amount of increase in volume would the bearings/rings/connecting rods see significant decrease in longivity ?

Usually in engine physics the hotter the engine is able to run the better the efficiency.

Will you need to increase the overall engine cooling capacity due to increased air entering the combustion chamber ?

I read the 18-25 percent figures from other stuff in earlier posts... I have a hard time believing that anything close to that amount of increase is available to an already turbocharged Diesel.... Am I just old and conservative/curmudgeon on this?

I once knew a guy with a Corvette that said he could feel the difference adding 8 ounces of NitroMethane to a 25 gallon tank of gas... I wonder if our machines would respond to that also...

leathermang,

I agree, the 18% is a dream.

The theory behind the increase in air allowing more fuel to be injected is sound. More air will allow more fuel to be introduced making more power. The amount of additional power is as you say, limited.

I have seen over the years, however, that there are some people that will go to extreme measures for minimal gains. The question is regarding, cost vs. result. For a street car, it's difficult to justify such an inordinate amount of time and money for a minimal gain, but I'm sure that there are people that will do it. I'm not one of them, but I would enjoy very much going through the research involved for such an achievement.

Your reference to more air and added cooling deserves some explanation. By the introduction of more air you bring the CC Temp down, by optimizing timing and fuel volume to maximize power with the CC Temp back to where it was, you have the same amount, possibly even a little less waste heat to dissipate via the cooling system due to increased efficiency.

This is proven out by the fact that since the over the road rigs started down this power/efficiency path via turbocharging/intecooling, their radiators have gotten MUCH smaller. Next time you see a long nose over the road truck such as a Pete or KW, notice the sloping hood. Before these more efficient turbo/intercooled engines, they could not do that because the radiators had to be enormous.

The increased efficiency turns more of the combustion energy into power and less into waste heat.

Have a great day,

I agree with both of your analyses, and while going through the pains of installing this system may not result in outrageous gains, do you think there will be any harm to these diesel engines? Even without a guarantee that an intercooler would increase the performance of my car, I would probably do it anyway because it gives me something to do That probably isn't a sound reason to spend a lot of money, but these cars break down so infrequently that I rarely have any good projects.

Alex

__________________
1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

I don't know enough to do the math... here is my guess....I think the actual increase percentage wise from the intercooler will not be enough to harm an already turbocharged engine.... but only because I think the amount of cooling will result in tiny extra amounts of actual air entering the chamber... now, if I am wrong on that part... and lets say it were to get near 10 or 15 percent.. then I would be very worried about the rod strength and the bearings... all of this is from intuition/30 years of mechanicing/reading about engines.....
The squish area on these engines is very small...
One thing on the heat dissapation these already turboed engines have going for them is the oil squirter aimed at the bottom of the pistons... the non turbo 5 cyl does not have that....

Larry, on the combustion chamber temps... although the air would be cooler entering the chamber... I assumed that more air in the chamber at the start of the compression stroke would cause the temp of the air to be higher when compressed... (?)

Ridge claims a 125F temp. drop.
I'm not certain how hot the compressed air is before entering the intercooler. The same volume and pressure cooled by 125F assuming an initial temp. of say 275F would yield an increase of about %10 air mass. Lower initial (pre intercooler) temp., would result in a larger air mass increase. (1.10nR x 373K = 1nR x 411K)
So how much does the turbo heat the air to begin with?

Well, couldn't that be determined by the amount of boost it is getting? Lets leave any turbo fan to fan convection temp out of the calculations... just try to determine the rise in temp due to turbo compression, then the amount of cooling which would be necessary to reach certain increases in volume into the chamber...? Or not, I may not be conceptualizing this properly anyway... anyone with ideas feel free to speak up....

If your intent is to maximize the amount of fuel injected into the cylinders, an intercooler will allow a proper air fuel mixture at a lower pressure. Thus, less work would be required during the compression stroke.

Here is the other part of the big picture which seems hard to actualize...

I am assuming no refrigeration equipment is being used... so we are basically talking about a heat exchanger... an air to air radiator...

So we have the air which has been compressed and heated some by the very act of compression... in a chamber which has tubes with outside,non compressed (except a little by the fan) air flowing through them.... this is what is going to suck heat out of the compressed air and be exited from the system...

How much ambient air at what temperature would be required to produce the effects being claimed?

I assume it would be more ( and I think MUCH more) than the amount of air being consumed by the engine...

at 2000 rpm the engine is consuming 3000 cc's times (1/2 times) {only half fire per revolution) plus the added amount of the boost... lets use 10 lbs .....

Lets assume some friction restrictions in the tubes of the cooling air...and that we need several times the amount being consumed by the engine in order to produce this much cooling...

Is the cooling fan capable of providing that much flow through this system ?

It's passive, no fans, just air to air heat exchange. ---sorry, actually for an added thrill one can spray water (via a windshield washer pump maybe) at the intercooler, taking advantage of the cooling effects of evaporation. This can also be useful on hot days to compensate for the lower before/after intercooler temp. ratio yielding lower air mass increase.
After thinking about it more, I may be wrong, but once combustion occurs, that cooled air will expand more than hotter air would have. This will enhance the expansion force of the explosion!
(Someone invented an engine that works strictly on the principal of warming air to produce expansion - it ran on liquid nitrogen which expanded tremendously when heated nearer to ambient temperature)
There is no argument here. People put intercoolers in turbo vehicles for a reason. As for my 300DT - my mind is made up!
(just don't know if I want the empty eyesocket look like ridge , I'm really quite interested in using the saab 9000 intercooler mounted in front of the radiator if I can find room... then I get the engine fan to assist in cooling at lower speeds!)
But alas, first comes the darned clutch slave cylinder replacement

I met a guy who had a '99 Dodge Cummins TurboDiesel P/U with a chip. bigger injectors, and PROPANE injection (similar to NOS in a gas engine). He told me that he dynoed th thing and it had over 1200FT. Lbs of torque at the rear wheels. This was a dually also. That is alot of torque !!! You can do some serious damage with those figures.

Now my point.. Turbocharging, intercooling, and whatabout the propane injection? This may be a very sweat combo in a w123 diesel.

Anyone have experience with this? maybe something to try....

__________________
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87 300SDL
81 300SD

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leathermang,

I think that the part of this that I am not explaining properly is the stoichiometry. In a combustion process there is always a particular optimum relationship of fuel and oxygen that provides the highest percentage of usable pressure vs. wasted energy. This is the stoichiometric ratio. At this particular ratio you are wasting the least amount of heat, which must be dissipated via the circulating oil and the circulating coolant. On a diesel if the amount of air remains relatively the same, the waste heat is not on the excessive side until you introduce too much fuel. So basically, to use a gas engine term, lean condition in the diesel does not produce excessive waste heat.

If an acceptable ratio is not reached, you will be making less cylinder pressure to be converted into torque and at the same time more heat that must be taken away by the cooling system.

So, if you are introducing more air, the heat generated by the compression of the air is neglibible as compared to the heat generated by combustion. So as the air flow increases, you can then introduce more fuel to the combustion process and if you do not go on the "rich" side of stoichiometric in a diesel, the combustion will develop more cylinder pressure with minimal waste energy(heat.)

In a gasoline engine, as the fuel/oxygen ratio gets too lean, the combustion process makes less pressure and more waste heat. This is why a really lean condition burns holes in pistons, burns valves, etc. Again in a gas engine, excessive fuel does not create excess waste heat, it's certainly not a good thing because it wastes fuel and washes oil off of the cylinder walls. In addition in a catalytic converter engine, it plugs up the converter.

In a diesel engine things are different, all of the reasons why are not clear to me, but as there is MORE fuel added with the amount of air remaining the same, the cylinder pressure indeed increases, but even with the "lean" condition there is not excessive waste energy. Once you reach a point of too much fuel and not enough air, this condition creates more combustion pressure but creates an inordinant amount of waste heat.

The diesel engine is so different to a gas engine in so many ways, it confuses many people. In the agricultural community where I live, the diesel 1 ton pickups and flat beds are becoming very common place. I get a giggle out of the number that I see with dual exhaust systems modified onto them. Outside of reducing pumping losses, these cowboys are seeing no power or fuel mileage gain whatever unless they are turning up fuel delivery in some way.

Please excuse my rambling,

"Once you reach a point of too much fuel and not
enough air, this condition creates more combustion pressure but creates an
inordinant amount of waste heat. " (Larry Bible)




I can see that being able to introduce more air/fuel (at the right ratio) would produce more power ... but it seems like if you introduce more fuel than you have oxygen to burn with it that that will not increase the heat/combustion pressure... but will in fact cool the mixture...(?)

leathermang,

That is exactly right in a GASOLINE engine. In a diesel, injecting too much fuel will produce SLIGHTLY more cylinder pressure, but excessive waste energy (heat.)

As I've said before, there are things about the difference between the diesel and gas combustion that I don't understand WHY they happen, but I know they happen.

Have a great day,