bigger head, more power or less?

[novatek]

Iv always thought that if you put a smaller head onto a a smaller bottom end

e.g - 1400 head onto 1600 bottom end

I would have thought that there would be more power because there is more compression, the same theory as when you skim the head :confused:

Does anybody have any facts about this please i just want to know if its better to put a bigger head on a smaller engine or a smaller head on a bigger engine!

cheers, Ben

[Snowface]

you would gain a slight amount through higher compression (1% perhaps).

But you would loose 10-15% by using the sh!t 1.4sr head as the ports are square unlike the nice curvy 1.6 GSI/GTE head.

[thirdeyeblindman]

use the 1300 one like they do in all the winnign stock rods over here

[Snowface]

Its better but not the best

Starting form worse the fit roughly like this in the scale of things

1.2i/1.4i/1.4sr--------1.2/1.3sr------------------1.4sri/1.6GTE/1.6GSI

[CP]

My son did it (mainly cos he didnt know what he was doing) You are right it does raise the compression ratio and it raises it lot! IIRC we worked it out to be something like 13.7:1! The horsepower gains from that kind of CR are considerable but the you would prolly need to run a 300 or similar degree cam with solid lifters and some race octane fuel with the timing set appropriately to realise the full potential. In any event it wouldnt last long as road car since engines with high CR's need to get upto temperature quickly and stay there ie run flatout as in race conditions. They dont take too kindly to getting hot and cold as can happen with road driving

[Rob-16v]

I put a 1.3 head on my 1.4 block with twin 40 webers "it went like a robbers dog"!............. for a day and then spat 3 rods through the block,two out the front and one out the back.lol got it on video some where.

[Sloth]

put the astra mk1 1600 head on it and run on optimax or talk 2 aragorn

[Snowface]

i was using a B+ 1.2 head on a decked overbored 1.3 block for over 12 months and it went like stink. Engine was still going strong when i went to 1.6.