High and low compression b18 engines

Natedog · Apr 30th, 2018, 19:47

Hi all, can anyone enlighten me of the difference in the two b18 engines used in the P1800, I’ve seen b18 and b18b, high and low compression

Army · Apr 30th, 2018, 19:55

https://en.wikipedia.org/wiki/Volvo_B18_engine

The higher compression ratio engine has / had a twin carb set up

arcturus · Apr 30th, 2018, 20:38

And different cam!

blueosprey90 · May 1st, 2018, 03:22

Compression equals horsepower.

jimbo1593 · May 1st, 2018, 10:36

I think CR is dependent upon the head gasket used and nothing more.

The high comp have twin carbs and different cams.

Derek UK · May 1st, 2018, 17:27

"I think CR is dependent upon the head gasket used and nothing more."

I think that is true on the B20 (?) but the B18 has different head thicknesses.
Doesn't stop you machining a B20 head and matching it with a head gasket to get the CR you want though.

amazon69 · May 1st, 2018, 18:07

I think B20's had different heights too:
http://www.v-performance.com/article...ification.html

jimbo1593 · May 9th, 2018, 15:21

You are right I was referring to the B20s.

Does head thickness matter in context of CR for a standard, non-skimmed head? Volume of combustion chamber is what matters. If you can up CR with a gasket change only I wouldn't worry too much about head height. If you think the head has been skimmed then get out the dial gauge, perspex and pipette and good luck to you. ;-)

Apr 30th, 2018, 19:47	#1
Natedog Member Last Online: Mar 13th, 2024 18:50 Join Date: Feb 2018 Location: Chichester	High and low compression b18 engines Hi all, can anyone enlighten me of the difference in the two b18 engines used in the P1800, I’ve seen b18 and b18b, high and low compression

Apr 30th, 2018, 19:55	#2
Army marches on his stomach Last Online: Feb 11th, 2022 03:15 Join Date: Jan 2018 Location: Somewhere in the Netherlands	https://en.wikipedia.org/wiki/Volvo_B18_engine The higher compression ratio engine has / had a twin carb set up __________________ 1961 Volvo PV544 the quick and easy in between project(!) 1981 Mercedes 300D <=> 230 diesel to petrol conversion project 1965 Series 2a Station Wagon mega build 1992 Mercedes 190E The car that works!

Apr 30th, 2018, 20:38	#3
arcturus arcturus Last Online: Apr 10th, 2024 08:21 Join Date: Mar 2006 Location: Sagres Portugal	And different cam! __________________ life's too short to drink bad wine

May 1st, 2018, 18:07	#7
amazon69 Premier Member Last Online: Apr 14th, 2024 15:15 Join Date: Jan 2006 Location: Falmouth	I think B20's had different heights too: http://www.v-performance.com/article...ification.html __________________ Falmouth, Cornwall. 1970 California white 131.

May 1st, 2018, 03:22	#4
blueosprey90 Master Member Last Online: Yesterday 22:18 Join Date: May 2017 Location: New Milford, Connecticut	Compression equals horsepower.

May 1st, 2018, 10:36	#5
jimbo1593 Master Member Last Online: Oct 1st, 2023 14:39 Join Date: Dec 2004 Location: leics	I think CR is dependent upon the head gasket used and nothing more. The high comp have twin carbs and different cams.

May 1st, 2018, 17:27	#6
Derek UK VOC Member Last Online: Yesterday 17:06 Join Date: Jul 2006 Location: Chatham	"I think CR is dependent upon the head gasket used and nothing more." I think that is true on the B20 (?) but the B18 has different head thicknesses. Doesn't stop you machining a B20 head and matching it with a head gasket to get the CR you want though.

May 9th, 2018, 15:21	#8
jimbo1593 Master Member Last Online: Oct 1st, 2023 14:39 Join Date: Dec 2004 Location: leics	You are right I was referring to the B20s. Does head thickness matter in context of CR for a standard, non-skimmed head? Volume of combustion chamber is what matters. If you can up CR with a gasket change only I wouldn't worry too much about head height. If you think the head has been skimmed then get out the dial gauge, perspex and pipette and good luck to you. ;-)

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