7M cylinder head porting

[enjoi.this]

My basic goal was on this port job was to make the head more free flowing but still retain as much of the stock port overall width as I could to prevent increased lag. Intake side was made slightly larger and made MUCH more free flowing (comparing to stock) then retextured with 60 grit paper roll. On the exhaust, where the 2 ports meet was knife edged and was smoothed out around the guide. I took as little as possible off so not too weaken the guide. Then was polished as smooth as my patience would allow.



Valves all removed from the head.

Heres some pics of the ports in stock form. I had troubles taking pictures of the exhaust side (camera wasnt cooperating)

These are the porting tools I used to do work. At my work we use these to do porting work on 2-stroke sleds, works out nicely when my wicked boss lets me work on my own stuff after hours :biglaugh:

How much I got done after 2.5 hours.

and a little over 3 hours and the intake side port job is done!

The almost finised exhaust side. Notice the knife edged area where the 2 ports meet.

Intake side all cut and texturized with 60 grit emery roll.

and... 5 hours later im done for the day. My eyes couldnt take much more after working a full shift :aigo:
I also posted this in my build thread.. http://www.supramania.com/forums/showthread.php?t=93365
Maybe others would want to see what I did and could build off of this. Im still not completely finished yet so if anyone with some more porting experiance has some tips and/or ideas for further work throw up a post.

 

[enjoi.this]

Oh and one more pic I have of a view from the bottom of the head.

 

[IJ.]

I'd radius the knife edge but that's just me

 

[enjoi.this]

My boss was telling me that it shoudl be radiused also lol. Does a round edge have better flow characteristics then a sharp edge IJ?

 

[IJ.]

It's less prone to fail Chris
(listen to your boss he's smart)

 

[enjoi.this]

haha will do ian lol. That really does make sense, since when Im doing cuts in aluminum sheets any sharp edges are drilled to stop them from cracking.

 

[IJ.]

Yep there's a LOT of stress on the exhaust side of the head and sharp edges are a good place for cracks to start

Don't forget the short turn radius it's VERY important for flow!

From the seat into the port

 

[enjoi.this]

Thanks for the info, next step im going to do more work on exhaust side. I really dont want this to fail any time soon. Wasted effort is not fun..

 

[IJ.]

7M ports aren't "bad" as is they just need some attention to the bowls and short turn radius and remember "even" is a bonus

Also DON'T port match the Header flang to the ports leave the ports smaller.

 

[enjoi.this]

Yess sir I did some reading up on port work of the 7m before I began :biglaugh:
Mostly on just not too do port matching on the exhaust side.
I smoothed out alot of the short turn radius's on both intake and exhaust. I was rather suprised how much work I could do around the guide. Is that what you ment as the bowl??

 

[IJ.]

Yep that's it

Don't go nuts and carve the end of the guide away it doesn't help flow that much and hurts valve life for a road car.

 

[enjoi.this]

Ive seen other port work where people have actually cut the guide itself down to almost nothing... These are also n/a builds for major hp goals. What sort of damage would weakening the vavle guide cause?

 

[IJ.]

Less support for the Stem so a little wear and you end up with wobbly valves that don't always seat in the right place and leak

 

[enjoi.this]

ahh ok that makes sense. I could see it also weakening the valve stem also. maybe even breakage from the increased movement?

 

[Guyana00]

Any more tips for porting the head? I do want to send mine to get machined for a new headgasket and I wanted to get it ported as well. I also read on this forum to not port match. Any other tip for me or the OP, from anyone?

 

[jdub]

You can port match the intake, but should not on the exhaust. Like IJ said, no need to go nuts...the head flows pretty well already. Porting will help on the higher HP motors.

 

[enjoi.this]

You can port match the intake, but should not on the exhaust. Like IJ said, no need to go nuts...the head flows pretty well already. Porting will help on the higher HP motors.

Yup I already port matched the intake side, just not the exhaust.

 

[87M-GTE]

^^^Why wouldnt you want to port the exhaust side? or the exhaust manifold to match the head ports?

-Sam

 

[Guyana00]

You can port match the intake, but should not on the exhaust. Like IJ said, no need to go nuts...the head flows pretty well already. Porting will help on the higher HP motors.

Thanks for the info, I'm just curious about the effects it would have on a lower HP motor, i.e. stock.

I'm acquiring an engine to rebuild and just want to find out as some extra info before I map out a plan. I'm aiming at 400+ but slowly modded over a 2 year range or so.

I plan to put internals that will handle that better than the stock internals so I don't have to worry and not tear back into the engine when it's in the car. Porting the head was something I was looking into and this thread came along

I asked my above question because I was wondering if it just wouldn't make a difference on lower horsepower motors or would the extra flow hinder performance.

I visualize the engine being more free-flowing and not making much difference as lower horsepower levels but I don't know much, which is an understatement so far about engine dynamics or physics. I'm in the learning process right now. Thanks

 

[ask92]

dannng that looks great!