I was reading here recently that the Evo 9s cylinder head is different in the water jacket area to the 8 and earlier ones .
Can someone tell or show me the differences in this area please .

Do we think that it could make enough of a difference to cooling and detonation resistance to use it on an 8 or earlier engine .
Lastly is it possible to run 8 cams and pulleys in the 9 head ie earlier parts to at least short term avoid the Mivec complexities .

A .

 

i have heard of people running non mivec cams in mivec heads, but that was a very very serious drag car.

unless you are running massive amount of power, i dont know why you would want to get rid of mivec. its not that complex >.<

 

Its not a case of getting rid of it but running that head in a car not designed to have Mivec or control it .
The focus is on better cooling and therefore detonation resistance . I think I remember reading that the 4G69 block also has larger cooling passages like the E9 head which is handy along with its 86.5 ? mm bores .

Also what sized spark plugs did these 9 heads run because I read they are smaller than the ones in the pre Mivec heads .

Cheers and thanks , Adrian .

 

disco, I have been planning this same move with my evo 4 project. I am going to run the 9 head with 8 cams. The spark plug is long reach which cools better. And the cooling passages are said to be better. I have too many things to do to the car to consider swapping harness to 9 spec so i can run mivec. But I will have that option for later down the road.

 

Has anyone ever cut up a 9 head casting to compare with the earlier 4-8 ones ?

Cheers A .

 

Most of our comparison has been just from porting the head and not from cutting up castings. The water jacket on the exhaust side is very similar but the IX seems to be a little thinner on #1. VIIIs seem to be far more prone to core shift and odd bowl shapes. The IX has more inlet flow stock since the casting "bumps" are on the exhaust side and not the intake like the VIII. Material is also a slightly different series, the smaller plug keeps the head stiffer as well and less likely to flex at high load. Not sure on how much percentage of change that would be though.

Hopefully some of that was helpful

aaron

 

Marco makes the parts needed to eliminate the mivec.

http://magnusmotorsports.com/?page_i...&product_id=85

Jerry, for what I assume your goal is with this car (wicked street car like always) I do think it would be worth the effort to run the mivec.

Fathouse

 

Hi all , the reason I'm asking is because I wanted to know if the 9 head is the best from the 4-9 range . I understand there are some water jacket differences and that the spark plugs are different - smaller . It was mentioned in the 4G64 or 4G69 thread that the Evo 9's head has better cooling passages inside the head casting and this is supposed to slightly reduce the detonation threshold in these engines .
At this stage I should also ask if the manifold stud patterns are the same on all 4-9 heads , 6s don't have EGR so the std inlet manifold would be handy to keep .

It was mentioned that the 4G69 being one of the later in the 4G family has larger cooling passages around the cylinders in the block and this matches the passages in the Evo 9 heads deck face . I have to assume same era same updates .
Where the 4G69 comes into it is that it looks like a handy way to have a larger almost square engine and potentially a longer stroke in a block dimensionally the same as the std one . Also it sounds like all the externals and ancillaries go straight on a 9 headed 4G69 .

One thing I'm curious to know is what that plug/plate gadget does on the Mivec delete kit , the other blanking plate is self explanatory .

Just wanting to know the potential of the best factory bits , cheers A .

 

I highly doubt any difference in water jacket is going to have any net impact on the performance.

Unless of course they prevent you from porting the head to the needed amount.