Its not perpetual motion or anything like that. Its just the more efficient use of energy. Similar to the way a heat pump is more efficient than an electric heating element. Or the diesel cycle is more efficient than the otto cycle.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

and a diesel typically already has plenty of air, and is throttled via quantity of fuel injected. In the otto cycle, air is throttled and fuel is necessarily mixed in to a stochiometric ratio.

An additional overabundance of air in a diesel does not provide a net energy output without an input.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

You can intercool all you want, and/or force 100psi of air in there, but you'll get ZERO power gains if there's no change in fuel delivery. Simulations are not the same as the real world. Intercooling adds plumbing length, loss of boost, and turbo lag. High boost pressure creates exhaust backpressure as well as higher IAT's. None of these things make power. I've already proved on my car that there is zero power gain with the boost turned up from 12psi to 18psi. (Same fuel curve, more air, no extra power - just hotter IAT's.)

The way to make power is to add FUEL, and keep the EGT's to non-melting levels by somehow reducing the IAT's (usually via intercooling). I can't believe we're having this discussion all over again, it's deja vu all over again with the Ridge saga...

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Dave
Boise, ID
Check out my website photos, documents, and movies!

True its more than just adding boost. Fuel delivery timing has to change as well to take advantage of the boost. In my simulation the cut off ratio of the diesel cycle had to change to keep the diesel cycle ideal when boost was increased. With this adjustment you will get more power for the same amount of fuel burned with more boost. A proper IP does this adjudstment to compensate for boost at all throttle settings, this is why we have the ALDA on the IP.

True the ALDA causes moe fuel to flow with more boost at the same cut off ratio. However when it delivers the same amount of fuel at different boost levels the cutoff ratio is different and you still get more power out at the higher boost level.

Now if an engine has more boost than the ALDA is designed to deal with you may see no gain in power and in some cases a loss. This also means that intercooling will require adjustments to the ALDA's settings because the mass of the air in the cylinder will change for a given pressure and the IP has no sensor to adjust for inlet air temp.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

Don't be offended, but drop it Clark. No one here believes this line of hypothosis, and it's be hashed and rehashed. If more air=more power all engines would be forced induction and be running stratospheric boost pressures. Engineers are the guys that go back to the drawing board when the mechanic tells them the stuff you says is gonna work just fell apart. Besides, we don't want to hijack this thread.

I've tried to run 20psi boost in the past and did some 0-60 runs. (This was back with my 300TD.)

13psi boost at an 800ft altitude gave me 15.5 seconds 0-60 average over 3 runs.
20psi boost gave me 15.3 0-60 average over 3 runs.

By the "more boost = more power" method, I should have seen far more than a .2 second difference.

There have been only three things I've done to get any major changes in power:
1: Adjust the ALDA to max.
2: Raise the boost from 9psi to 13psi.
3: Increase the accelerator travel stop 4mm.

Simple science will proove "more boost = more power" false.

As far as I can tell, the original poster set up his VNT to make boost all the time. Therefore, whenever he moved the throttle enough to get the IP out of idle mode, the ALDA gave it throttle, and he could cruise down the freeway with just a touch of the pedal. Kind of like some GM vehicles which were set up to make the throttle extra sensitive in the early part of the pedal travel. This makes the car feel very powerful, but when you put it to the floor, it isn't any more powerful than before.

One of the Finns, Paloviita, put an electrically operated GT23 series VNT on his 2.5L. He used a microswitch on the throttle linkage to keep the boost turned off at low throttle. I always thought he did it to reduce exhaust pressure and save fuel, but now I wonder if he did it to keep the throttle from becoming hypersensitive. He probably explained his reasoning here, but I can't read Finnish:
http://mersuforum.net/forum/viewtopic.php?t=25466

I'm also planning a VNT installation on an OM602 in a few months. When I get it working, I'll check the freeway mileage with and without boost. Since it normally takes about 2 bar of exhaust backpressure to make 1 bar of boost, I suspect that extra boost without extra fuel helps power about as much as a banana stuffed in the tailpipe.

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'79 300SD W116
'86 190E 2.3-16V W201
'92 300D 2.5 W124
'99 E320 4MATIC S210

A bit off the topic, but, I have to laugh at this one. I remember when GM invented the "leap" off the line. What they did was to put 20 degree throttle plates in the carburetors. So, when you crack the throttle, the angle of the plate allows a massive amount of air to flow, almost instantaneously. Naturally, you only have 70 degrees of opening available, and, IIRC, about 30% of the air was introduced in the first 10 degrees (from 20 to 30 degrees).

Everybody copied that design and it remains to this day in some fashion. I'm not sure how they simulate it with fuel injection.

Exactly what turbo should I be looking for if I want to copy this? I don't think it's clear what turbo is being used.

If "more boost = more power" is false then why did you see any gain? If it was false you would have seen a loss due to more back pressure as some have suggested. You did see a gain and that is proof that more boost = more power.

In my simulation I saw a increase of about 10% from no boost to 7.25 PSI for an ideal cycle in an ideal engine. There are several factors that will reduce this gain signifigantly including increased energy lost to the cooling system during compression stroke and increased backpressure due to the turbo. I will admidt at some point the energy used to create this boost may exceed the amount gained, however you are very unlikely to see this situation with a production engine before it blows up or melts.

I have never claimed that just increasing boost will get you more power than increasing boost and fuel flow. This stated, If you can increase boost at a given rpm over normal levels that doesn't exceed what the ALDA was designed to deal with, the IP will compensate and add more fuel automaticaly giving you both power increases. A VGT will allow this, especially at lower RPMs where a normal turbo can't muster boost.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

...his increases in power were so negligible that they were easily within the scope of % error. Also there are so many envrionmental factors that I can't even begin to list them.

You want to stand behind your argument, thats fine with me...but if you expect anyone else with a lick of common sense to believe you, you need either SAME DAY dyno numbers (no if, ands, or buts) with the only variable being boost pressure.

Or if you can find an example of someone else doing this for you, you are welcome to point it out.

I am sure everyone here is willing to admit they were wrong (myself included) if you can find us some solid data to analyze However until then, expect some skepticism.

Enjoy

Hopefully this will end the argument. It will probably just start another one on whether it can be shown on a production engine however.


This article focuses on emissions reduction but they do show that more boost = more power for the same amount of fuel.

http://www.erc.wisc.edu/publications/thesis/thesis/thesis_Tanin.html

near the end of the third paragraph "BSFC also reduced monotonically with increasing boost pressure for all cases." (for those that don't know what BSFC is, Brake Specific Fuel Consumption is the ratio between the engine's fuel mass consumption and the crankshaft power it is producing.) A reduction in BSFC means the same power is being produced with less fuel. So with the same amount of fuel being burned you will get more power with more boost.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

That's something I intend to test eventually. Hook up a fuel bottle to the fuel supply and return lines, take a 20 mile trip down the freeway, and see how much mass the bottle lost. Refill the bottle, change timing, boost, whatever, and repeat.

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'79 300SD W116
'86 190E 2.3-16V W201
'92 300D 2.5 W124
'99 E320 4MATIC S210

A dyno would be more accurate...

20 miles is a LOT of variables...espically considering a manual input (the go pedal) is pretty hard to repeat exact conditions.

There is a guy near the place where my friend is having his baja bug built that has a AWD dyno. We are gonna talk to him next time and see if he is chill and rents dyno time.