Help Me Calculate Compression Ratio

[christopher 5 1 Cars]

Can someone help me calculate the compression ratio of the engine I might build?

 

basically it is a 1587cc block and a TU24 head.

 

I get 8.6 which just can't be right...

 

 

Bore = 78.5 mm

Stroke = 82 mm

Head Gasket thickness = 1.5 mm

Deck Height = 2mm

Measured volume combustion chamber 32.4 cc

[DrSeuss 0]

http://not2fast.wryday.com/turbo/compressi...mpression.shtml

 

Thats a really good compression ratio calculator.

[christopher 5 1 Cars]

Cheers DrSeuss,

 

I've tried one of these but just can't get it right if I use the given combustion chamber volume?

 

Hence the question

[DrSeuss 0]

according to the figures you posted, i got around 9.67:1

[tom_m 0]

using that calculator and your measurements, i make the static CR 9:1

[christopher 5 1 Cars]

I just don't get it. I expect a TU5 combustion chamber (106 Rallye) to be bigger then a TU24 (1,3 Euro Rallye) so the CR should go UP if I put the TU24 head on a TU5 block

 

A 106 Rallye has a CR of 10.2

 

A 205 Rallye has a CR or 9.6

 

Now I'm still confused

Edited January 21, 2006 by christopher

[crogthomas 0]

Calculating it by hand I also get 9:1 using those measurements given, assuming that by deck height you mean the distance the piston is down the bore at TDC?

 

What other differences are there?

Are the pistons flat toped?

[Rippthrough 98]

I just don't get it. I expect a TU5 combustion chamber (106 Rallye) to be bigger then a TU24 (1,3 Euro Rallye) so the CR should go UP if I put the TU24 head on a TU5 block

 

A 106 Rallye has a CR of 10.2

 

A 205 Rallye has a CR or 9.6

 

Now I'm still confused

 

 

Is that the compressed head gasket thickness?

[christopher 5 1 Cars]

that the compressed head gasket thickness?

 

I dunno I suppose it would be a standard 106 Rallye cast iron gasket I would work from. I just measured the old one

Edited January 21, 2006 by christopher

[christopher 5 1 Cars]

I'm getting the same result about CR=9. This means that the combustion chamber on a TU24 Euro Rallye is actually BIGGER then a TU5 one Can this be???

[B1ack_Mi16 67]

It gets at 9:1 with your information, are the piston flat-tops? Do they have valve-cutouts?

Edited January 21, 2006 by B1ack_Mi16

[trogboy 17]

I'm getting 9.04:1

 

Like B1ack_Mi16 said, are you sure of the bottom end/piston data? i.e. deck height, flat topped, deck height, crowns, dished, cutouts etc.

 

Also what have you used to measure the thickness of the used head gasket?