Stock 7-Bolt DOHC Compression ratio

[tektic]

I have looked every where for the answer to these question so now its just time to ask.

I have sourced a 7bolt 1993 mighty max engine, and i have a built 6-bolt 4g63 dohc head.

My questions are if i put the dohc head on the stock 7-bolt bottom end what would the compression ratio be?

or

What is the volume of a 7-bolt 8 valve sohc head?

I figure if the guys with spyders can get away with a stock bottom end so can I. I just dont know if the 8 valve and 16 valve heads have different cc volumes.

What about valve reliefs on the stock mighty max pistons? will it clear the dohc valves?

Thanks in advance guys

[Bulletupfl]

I have been wondering the same thing I'm guessing u can get away with putting the dohc head on a stock max engine since the guy with the Montero/pajero/raider build is doing it from his pics it looks as tho he is keeping the stock pistons and running a turbo but any one else's input would be great I'm wanting to run a higer comp na 4g64 in my Montero

[tektic]

Still would love an answer to this. I have a 6 bolt 2l and am considering a 2.4l 7 bolt truck. One will get a dohc head soon. Looking for pistion relief facts and compression numbers.

[Silverjoel]

http://www.mightyram50.net/vbulletin/sh ... pecs/page2

[tektic]

So a 93 head would be 47cc and the earlier is 68cc? Do valve reliefs need to be cut into the pistons or is a dohc head swap possible on a stock 7 bolt bottom end? That is really all i need to know. I guess I'll have to take it apart myself.

[xJLCx]

mighty max and d50's were all 8v headed engines so pistons which when placed in a dohc setup (valves will not clear as there are no valve reliefs for them anyway) would yield roughly a 12:1 comp ratio.

for the record 6 bolt and early 7 bolt heads are 47cc chamber heads
evo heads are 43cc chamber heads
Hyundai 1.6 dohc heads are 37cc chamber heads. (for shits and grins if you used this head comp ratio would roughly be 14:1)