8v bottom end with 16v head?

[RobMarriott]

Would it work?

My head is telling me that an E16SE bottom end with a C/X16XE head would make a low compression 16v?

Am I right or am I miles off?

[Adam]

E16se bottom end would probably put compression up tbh.
As its not designed for 16v cams(piston dishes etc)

[Mike]

Stuart's your man for this one i think, i cant see why not tho?

[bieransri]

i looked in to this, think chris astley used it the other way round. but ide be intrested in this also as im looking to build a c16xe nova

[Mike]

im sure some of the rally guys i know used to run engines like this, or the other way around...

[philly]

it could be possible as they are able to do it on fords and build zvh's with cvh an zetec parts so cant see why there isnt a way to do that

[Philsutton]

you will need the pistons that match the head to on the block though

[burgo]

bottom ends are identical apart fromt the pistons due to the valve cut outs

[RobMarriott]

So where is the difference in C/R from? The pockets in the pistons or is it in the head?

[burgo]

probably a mix of the two

[bieransri]

so to use the 8v block 16v pistons would be needed. therefore being very little rise in CR as if its the pistons that give the gain there wouldnt be any because the 16v pistons would be used?

[Adam]

Why not just use a 16v block?

[bieransri]

think robin was hoping that using the 8v blocke and pistons would be an easy/ cheap way of getting the cr up

[Adam]

I'd say down going by his supercharger thread.

Just get the standard pistons skimmed to reduce CR.

[bieransri]

yea i know whatyour saying, i just though they were two seperate ideas:confused:

[Ash]

the 16v head must have more 'room' in the valve area as my 16v pistons are flat, so no room for the valves to come down any lower... so 8v pistons/bottom end with a 16v head would work and would lower compression but only very sightly, plus the 16v pistons/bottom end would be stronger. If your on a budget use a spacer plate and dont hammer the engine too hard.

[Adam]

The pistons are flat as the 16v motor runs a higher compression ratio than a 8v.
So thinking about it, 8v pistons with dishes/cutouts would lower cr as you said.

You'd have to measure it to find out how much tho.

You could look at using a SPI 1600 8v bottom end, as im sure they are lower cr than mpi.

[Ash]

You could look at using a SPI 1600 8v bottom end, as im sure they are lower cr than mpi.

I never knew there was one, not in small block anyway.

[Adam]

There is.

Only 1800Spi was a big block.

[Ash]

yea, i was thinking 1.6 carb - 16sv i think.

[Chris Astley]

There is 2.5cc difference in the dish of the 8v to 16v pistons, 8v pistons having 5cc dish and 16v piston having 7.5cc dish which means if the valve to piston clearance was ok with the 8v pistons and 16v head then the compression would be higher. Other problem that you will have is that the 8v and 16v engine use different cam belt types, the 16v wont fit onto the 8v crankshaft. Also you will have to change the bottom pulley for the crank sensor pickup, which will also involve changing the oil pump as the 16v pump has the crank sensor bracket mounting lugs on, the 8v pump doesnt. Another problem is that the 16v has extra threaded holes in the end of the block were the cam belt tensioners fasten, these arent in the 8v block.

Chris Astley.

[Stuart]

CP modded an 8V block to run with his 16V head.... its not ahrd to machine the block to suit... i belive it was done taht was as at the tiem 16V engines were still more than the machining costs lol.

the 8V head onto a 16V bottom end comes from the rally folks not being alowed to rebore for certain regs and the best way to get a good condition bottm end is to use the 16V as its likely to be newer and less funked.

[Chris Astley]

The reason most people use the setup i did as you mention above with the 8v head and 16v bottom end is because the pistons and crank are stronger! Condition doesnt matter as if its for a rally car you would be rebuilding it anyway.

Chris

[Stuart]

some regs say you cant rebore so that reason stands.... unless youve got a supply of brand new 8v blocks hiding somewhere lol

[Chris Astley]

Most rules appreciate the age of the engine and allow first oversize.

[Sirnixalot]

rallyman you might have some info that im looking for. would you happen to know the combustion chamber volume of a 1.3sr head?

thanks for your time:thumb: