1.8 heads on a 2.5 block

nycstreetsoldier · Post by **nycstreetsoldier** » May 30th, 2008, 11:27 pm

anyone ever herd of anyone doing it?or know if it might work?annyone know the valve size of the k8 or the ze?let me know

Daninski · Post by **Daninski** » May 30th, 2008, 11:43 pm

My only question is why?

nycstreetsoldier · Post by **nycstreetsoldier** » May 31st, 2008, 12:02 am

just something new and i have some extra parts laying around...do you know the valve size's at all?

fowljesse · Post by **fowljesse** » May 31st, 2008, 12:38 am

My guess is that it would be hard on the rings to pull/ push the air through the smaller ports. It would be alot of work for a lark. maybe you could port the heck out of them. Who knows.. maybe it would create an awesome combustion swirl, or something, and be one of those innovations we would have never thought of. If you do it, let us know how it goes!

Daninski · Post by **Daninski** » May 31st, 2008, 12:42 am

I think it would be interesting to see how the ECU handles it. How about 1.8 heads with boost?

se7en · Post by **se7en** » May 31st, 2008, 3:20 am

lol, my k8 heads handle boost just fine

nycstreetsoldier · Post by **nycstreetsoldier** » May 31st, 2008, 11:34 am

im going to try it and im going to be running boost as well, so i hope it turns out to be somthing good...if anyone has anny more info let me know

se7en · Post by **se7en** » May 31st, 2008, 12:12 pm

um, I would makes sure that the k8 heads don't have a smaller combustion chamber, as that would raise the compression too high...

mitmaks · Post by **mitmaks** » May 31st, 2008, 1:44 pm

guy at work put 305 heads on 350 block, says he's got more hp now but only way would be to find out is to dyno it. If you dont have nothing to lose Id put those heads on and see how it runs, of course you will need some premium gas, maybe some toluene to prevent detonation.

nycstreetsoldier · Post by **nycstreetsoldier** » May 31st, 2008, 2:50 pm

ok thanx...anyone know the exhaust port size on the k8,and the klze so i can compare the diff...

se7en · Post by **se7en** » May 31st, 2008, 3:54 pm

um, those 305 heads you talk about....

they have s--- small ports, and only gain minimal HP because of the slightly raised compression ratio....the valves are also way smaller...

totally not a swap that is worth it....

you might gain a few ponies down low, but up top, all HP would be lost, and then some.

Daninski · Post by **Daninski** » May 31st, 2008, 4:38 pm

Do a wet compression test after you install the head and compare that to what a normal 2.5 should be.

mitmaks · Post by **mitmaks** » May 31st, 2008, 4:55 pm

se7en wrote:um, those 305 heads you talk about....

they have s--- small ports, and only gain minimal HP because of the slightly raised compression ratio....the valves are also way smaller...

totally not a swap that is worth it....

you might gain a few ponies down low, but up top, all HP would be lost, and then some.

I was thinking what would be result if you swapped 350 heads on the 305 block instead?

se7en · Post by **se7en** » May 31st, 2008, 8:16 pm

Lol, that;s even worse...350 heads have big chambers(except the old stuff) and on a 305 would make like 6:1 compression ratio.

7

nabp · Post by **nabp** » June 1st, 2008, 2:16 am

K8 INT valve is 28mm / EXH valve is 23mm

Exhaust port size is the same on all K's as I understand it.

*IF* you could get it to actually work (head gasket issues, different chamber size, etc), your low-end torque would likely increase at the expense of the top-end...... worth even trying???

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1.8 heads on a 2.5 block

1.8 heads on a 2.5 block

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