Author Topic: IDI - effect of reducing compression ratio on hp & mpg (Read 53654 times)

jimfoo · « **Reply #90 on:** June 13, 2007, 07:34:14 am »

While not related to diesels in general, I did find a very interesting patent related to squish areas of gas engines, claiming to greatly increase efficiency as well as reduce/eliminate pinging even on low octane. I also found a forum where people have tried this idea, and it seems to work.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6237579.PN.&OS=PN/6237579&RS=PN/6237579

saurkraut · « **Reply #91 on:** June 13, 2007, 09:36:16 am »

The piston periphery section 29 forms a squish area 31 of the combustion chamber 44 with the surface 48 of cylinder head 16. The squish area 31 allows more volume to be adjudicated to the lobes 20 and 22 and promotes rapid air motion into said volumes as the piston reaches TDC on its compression stroke for faster mixing and burning with the flames exiting out of the prechamber through the transfer passage (which have not yet been described).

Risking the peril of provoking some prominent rockit scientist on this board, I humbly ask for a link to this excerpt. I'd like to read the whole document. The TD SAE paper doesn't go into this much detail.

jimfoo · « **Reply #92 on:** June 13, 2007, 09:55:56 am »

It was mostly on the benefis of 4 valves as opposed to 2.
http://www.patentstorm.us/patents/5309879-description.html

saurkraut · « **Reply #93 on:** June 13, 2007, 10:26:46 am »

Thanks!

Mark(The Miser)UK · « **Reply #94 on:** June 13, 2007, 10:54:10 am »

Mr Saurkraut I concede the 'Squishy/squashy' bit was a little light relief :lol:
I still seem to have missed references linking s/s to diesels. in particular IDI diesels.
I do admit that in a single chamber setup the final few mm in of travel would produce accelerated movement of small quantities/(large q small vol) of air or mixture. But where it has to go round a corner into a fixed aperture swirl chamber it must be slowing down again as its being pushed by a slower piston that was previously pushing air through at a faster rate.
Maybe where we differ the most is that you are predominantly looking for more power [with probably a hope for a sustained fuel economy] and this may well suffer from thicker gaskets; whilst Im searching for better economy [and if it means I have to suffer with the temptations of greater power so be it] but I find that a slightly tweeked Quantum TD is quite responsive and defiinitelyhas more acc'n under load than its 1.6 gasser brother. Top speed in a Q TD? I've never been able to find it... 105mph and I gave up as our sneaky timed distance cameras we have here will shoot me down knowing my luck :shock:

Jimfoo
I looked at some of those patents through the Patent Storm site. But the content is hard to follow without the pictures. Unless you can see where they are located :?: ...

jimfoo · « **Reply #95 on:** June 13, 2007, 11:16:21 am »

No, I was looking for them too.

Mark(The Miser)UK · « **Reply #96 on:** June 14, 2007, 01:28:41 pm »

In response to an earlier query as to why would vw bother to issue different gaskets rather than just a 3 notch...

Because vw block/crank and pistons all vary by their reasonable tolerances; one method other than more accurate machining which tends to be come prohibitively expensive; (imagine the cost if the engine was built like the Bosch pump) is to use different sized gaskets take up the slack. This was felt neccessary to try and standardise the performance. Remember the engineers thought it neccessary to offer 5 gaskets at first before reducing to 3 ... maybe 1 will be the way in the future.

saurkraut · « **Reply #97 on:** June 14, 2007, 02:22:10 pm »

Yes, its obvious why there are different head gaskets: tolerance stack up. It manifests itself in piston protrusion.

But what are they trying to control. I would offer that its not compression, as we have seen that the min/max gasket thickness changes compression very little. Are the trying to controll the gap between the piston top and bottom of the head for some other important reason?...

I even wonder what the manufactureing variability in the swirl chamber voluum is. Is that variable enough that the actual compression is a range of 22:1 to 24:1

jimfoo · « **Reply #98 on:** June 14, 2007, 02:42:26 pm »

Probably so the pistons don't strike the head. Remember that things like connecting rods and pistons expand when they get hot.

burn_your_money · « **Reply #99 on:** June 14, 2007, 04:32:50 pm »

Quote from: "jimfoo"

Probably so the pistons don't strike the head. Remember that things like connecting rods and pistons expand when they get hot.

If that was the only reason why would they have made 5 (and then 3) different thicknesses? It would have been cheaper to just run the thickest gasket if interference was the only concern

Mark(The Miser)UK · « **Reply #100 on:** June 14, 2007, 05:04:08 pm »

Quote from: "jimfoo"

While not related to diesels in general, I did find a very interesting patent related to squish areas of gas engines, claiming to greatly increase efficiency as well as reduce/eliminate pinging even on low octane. I also found a forum where people have tried this idea, and it seems to work.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6237579.PN.&OS=PN/6237579&RS=PN/6237579

Found the missing images :shock:
Don't ask me how 'cus if I told yer I'd have ter kill yer :mrgreen:

Definitely linked to DI engines only in this case according to pics :!:

Mark(The Miser)UK · « **Reply #101 on:** June 14, 2007, 05:31:03 pm »

Quote from: jimfoo

It was mostly on the benefis of 4 valves as opposed to 2.
http://www.patentstorm.us/patents/5309879-description.html

And 4 valve diesel stuff
Don't ask :wink:

:mrgreen:

jimfoo · « **Reply #102 on:** June 14, 2007, 07:23:05 pm »

Quote from: "Mark(The Miser)UK"

Found the missing images :shock:
Don't ask me how 'cus if I told yer I'd have ter kill yer :mrgreen:

Definitely linked to DI engines only in this case according to pics :!:

On his website he claims for all internal combustion engines. I never found where anyone had tried it on one though, although some big diesel semi's had tried it, but the people hadn't told him the results. If you look at the how to make your 1.6 TD rev higher, or whatever it is thread, the mod there is supposed to create more turbulence also. So I bet it could be done on an IDI and achieve similar results, plus it will lower compression for better economy.

"US Patent 6237579 is applicable to any 2 or 4 cycle internal combustion engines featuring " Squish or Quench " concepts. The placement of one or more grooves or channels or passages in the squish area as shown & described in the first page of my US Patent 6237579 results in "Accelerated Laminar Total Clean Burn Combustion " out of any fuel ? Meaning to say, this simple but radical design change to squish areas & configurations enhances progressive turbulence in the charge close to the skin of the combustion chamber and further directs the (added) turbulence towards the igniter followed by multiple flame front propagation thus resulting in a radical change to " In-cylinder Combustion ". This technology is as radical a change to engine design as it was with the introduction of the ' quench ' concepts by Sir Harry Recardo almost 80 + years ago. ALTCBC improves " Torque & Power " through the entire operating range with lesser amounts of fuel. This simple design change "opens up" the combustion chamber to activity. Hi-Breds can now benefit from the enormus low-end torque produced out of smaller displacement engines to pull away with ease. Simplicity in design is the key to keeping costs down and pays on the long run !
After this simple design change ~ Obsolete Side Valve Engines which feature large quench areas have shown reductions of up to 42.5 % in fuel consumption ( BSFC) when fully loaded at 2000 rpm on the dyno further producing more torque & power at lower operating temperatures in comparison to a stock engine. ( ARAI Test Results )"

jimfoo · « **Reply #103 on:** June 14, 2007, 08:25:27 pm »

Maybe it is just the DI as I found this.
"My experiments over the years lead me to some definite conclusions & proof of improvements in the area of Thermal efficiency gains - Both DI Diesels & Petrol engines respond to this design change almost in the same manner - If done on the piston crown ! Provided the Piston has a Dish. You can run petrol engines incredibly lean without any hick-ups or heating-up or stalling !"
I e-mailed him to ask about IDI engines.

Mark(The Miser)UK · « **Reply #104 on:** June 15, 2007, 01:50:42 am »

If my memory serves me correctly (which it may not) the threads on this site dealing with the grooving of the piston were to direct the burnt fuel towards the exhaust valve; which in turn was hoped to help through flow and thus increasing revs. I think maximising revs then encountered the problem of the follower in the pump launching off the cam and so leaving the injection piston behind....