Variable compression ratio engine!

amitoj · 14th December 2005, 15:37

Hi

Long time since i started a thread.

A friend of mine sent me a link to an article that explains an engine developed by Saab that can vary its compression ratio from 8:1 to 14:1 depending on the load on the engine! As per the article, Saab says that it reduces fuel use by 30 percent and the engine is as powerful as an engine twice its size. However, this is still under R&D phase and still long way away from production.

Here is Ze Link

Shan2nu · 14th December 2005, 19:11

From 8 to 14 on a petrol engine???? What kind of fuel will you have to fill to run a 14:1 compression engine?

Shan2nu

Mpower · 14th December 2005, 20:34

Same fuel. It will run 14 under part throttle and 8 under WOT with max boost.

Shan2nu · 14th December 2005, 21:39

Quote:

Same fuel.

I know that but, what octane fuel?

Shan2nu

Mpower · 15th December 2005, 01:48

87-89 octane should be OK.

samcore · 15th December 2005, 23:32

According to my information variable stroke engines are used to measure the knock tendency i.e. cetane and octane numbers of fuels.

If you want to have a look, generate contacts and visit Themodynamics laboratories of IIT powai or Naval College of Engineering, INS Shivaji, Lonavala

newbie · 20th December 2005, 14:31

I dont get it. Do you mean like changing the compresion on the fly without opening the hood? If not it's not so impresive( an A series toyota can do that 9-15 last check).

sbasak · 20th December 2005, 14:45

see here
http://en.wikipedia.org/wiki/Compression_ratio

ananthkamath · 20th December 2005, 21:01

Quote:

Originally Posted by samcore

According to my information variable stroke engines are used to measure the knock tendency i.e. cetane and octane numbers of fuels.

If you want to have a look, generate contacts and visit Themodynamics laboratories of IIT powai or Naval College of Engineering, INS Shivaji, Lonavala

Right and wrong.

The engine your talking about is the CFR (Co-Operative Fuels Research) engine which can vary CR from 4:1 to 18:1 through a movable cylinder head. Obviously it is not practical in an automotive installation due to its single cylinder and purpose.

The engine designed by Saab also uses a movable cylinder head but it works in conjunction with a Rootes supercharger to maximise volumetric efficiency.

14th December 2005, 15:37	#1
amitoj Senior - BHPian Join Date: Nov 2004 Location: Windham, NH USA Posts: 3,348 Thanked: 3,105 Times View My Garage	Variable compression ratio engine! Hi Long time since i started a thread. A friend of mine sent me a link to an article that explains an engine developed by Saab that can vary its compression ratio from 8:1 to 14:1 depending on the load on the engine! As per the article, Saab says that it reduces fuel use by 30 percent and the engine is as powerful as an engine twice its size. However, this is still under R&D phase and still long way away from production. Here is Ze Link
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14th December 2005, 19:11	#2
Shan2nu Senior - BHPian Join Date: Feb 2004 Location: Hubli - Karnata Posts: 5,533 Thanked: 125 Times View My Garage	From 8 to 14 on a petrol engine???? What kind of fuel will you have to fill to run a 14:1 compression engine? Shan2nu
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14th December 2005, 20:34	#3
Mpower Senior - BHPian Join Date: Mar 2005 Location: Bangalore Posts: 10,409 Thanked: 1,730 Times View My Garage	Same fuel. It will run 14 under part throttle and 8 under WOT with max boost.
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15th December 2005, 01:48	#5
Mpower Senior - BHPian Join Date: Mar 2005 Location: Bangalore Posts: 10,409 Thanked: 1,730 Times View My Garage	87-89 octane should be OK.
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15th December 2005, 23:32	#6
samcore Newbie Join Date: Dec 2005 Location: Pune Posts: 2 Thanked: 3 Times	Variable Stroke Engines According to my information variable stroke engines are used to measure the knock tendency i.e. cetane and octane numbers of fuels. If you want to have a look, generate contacts and visit Themodynamics laboratories of IIT powai or Naval College of Engineering, INS Shivaji, Lonavala
	() Thanks

20th December 2005, 14:31	#7
newbie Newbie Join Date: Dec 2005 Location: dhaka bd Posts: 11 Thanked: 0 Times	I dont get it. Do you mean like changing the compresion on the fly without opening the hood? If not it's not so impresive( an A series toyota can do that 9-15 last check).
	() Thanks

20th December 2005, 14:45	#8
sbasak BHPian Join Date: Nov 2005 Location: CCU-LTN Posts: 608 Thanked: 14 Times	see here http://en.wikipedia.org/wiki/Compression_ratio
	() Thanks