Intake / head porting

[arrowheadracing]

Just wondered if anyone has ported the lower intake and saw good results. I see a couple of people have ported about 2 inches of the inlet side just off the turbo. I ve ported mine almost all the way to the bend. Cant see how just a little transition can make much difference unless there is a major restriction ( which there isnt ). I also ported the plenum area ( upper intake ) and smoothed and polished it. That suprisingly made a bigger difference then just enlarging the inlet tube. So my question, anyone gone farther and ported the lower intake and gasket matched it and if so did you flow bench it or just backyard it ? I guess my next step after that would be to port the heads and make a set of headers for the truck and and and.....


Thanks
Todd

[eracers999]

Hi:

As far as the lower intake here is what i just did to mine. I just blended that sharp turn from the top down into the runners.
There isnt a lot of material there to go raising the runner up much.
BTW, i cant get to your web site.
Kent

[arrowheadracing]

Sorry about the link to the website. We are in process of setting up a new site with more powder coat and welding/machine pictures. Probably be up the next month.

Did you notice any increase in throttle response ? Or for that matter any other improvements ?

I noticed a pretty healthy increase once I polished the plenum area. Nothing like 10-20 hp or anything like that, but just a smoother , crisper throttle response.

Thanks
Todd

[eracers999]

Dunno yet, in the middle of a major 6.5 build, porting the two intake half's is somthing that i just did yesterday.


Kent

[Mainous]

When I built my engine I gasket matched the lower plenum to the heads and also cleaned up the intake and exhaust runners and bowls in the heads. Nothing was ever flow tested. Just a pocket port job. There is a considerable amount of cleanup in the intake and exhaust runners. Most of what I did was contouring and blending, especially the short side radius leading into the valves. What was it worth in terms of horsepower and torque? It's hard to say. It is a turbo application so you are just increasing efficiency.
Be sure to gasket match your exhaust ports and manifolds too. Oh yeah, do this before you have the valve job done too. I had the heads cleaned and the sleeves installed, then picked the heads up to do the work. I cleaned all of the shavings out myself and returned them for the final valve job.

[cruzer]

I port matched also, I did nothing more than opened up the ports to gasket size and tried to transition it best possible. There is a lot of material to be removed between intake and head. Some ports I removed around 1/8" or more. Exhaust side needed less to be removed. No flow benching
done here, but I'm sure there was some performance gained, there was alot of material removed and i was there anyway. Did b4 heads went to shop.

[arrowheadracing]

The only thing of concern when you say you moved the port 1/8 ( or .125 ) is that actual flow #'s increasing does not mean an actual increase in performance. I ve been porting Pontiac muscle/race heads for quite awhile. And I can say from the experience with those in particular that low lift flow is getting you more power than high lift flow. So theory behind it is , that if you can make the low lift increase more than high lift then you will see more torque at the lower rpm. Too big a port and if you can push that much air into it, then you will have dead space to fill and the flow will slow down and lose velocity, even if you have large a quanity of air in there. And when I say low lift flow, I mean cam lift .450 "s , if you increase your air flow from .100-.300 lift off the valve , you see that area twice. Once to open and just before it closes. At .450 lift you are only seeing that flow # once, and thats when its fully opened. So backyard porting may actually hurt performance more then gain anything.

There is alot to know about porting a head then just grinding away. Shapes and contours and the short side radius are very important things to understand. Especially venturi effects at the bell mouth of the valve.

Anybody make aftermarket cams for these things ?

Thanks
Todd

[cruzer]

Is there going to be a ventri effect w/a engine
that has positive manifold pressure?

On the lower intake, where the intake ports meet the head is where the most of the material was removed. Minimal material was removed from the head itself. Just enuff to match the gasket so there would be a smooth transition. Do "search" on this subject, I know other people have had good results doing the same.

[arrowheadracing]

You wont have as much as an effect, but there will still be an effect. I d be interested to hear some results.

Thanks
Todd

[javadog]

The next person who does this could you take some before and after pictures?
Also, what is a plenum?

[arrowheadracing]

I have the pictures, but couldnt figure out how to post them on here. I am all ears if someone wants to give a tutorial on how to do it. Or I can just email the pictures to you.


Todd

[javadog]

Ask Jim or one of the computer gurus about posting pics. Sorry but I can't help you. As a last resort you could put them on webshots for free and post the link. We need a section on this website with pictures of sponsor's
parts, disassembly/reassembly steps, and common procedures.
You pros forget that there are newbies like me that
don't even know what a lot of things even look like,
or how to do something as simple as change a fuel filter.

[a5150nut]

Also, what is a plenum?

Intake manifold/runner

[arrowheadracing]

The plenum is the area in the middle of the intake. On a carburated intake it is directly below the carb/throttle body. It is the open area before it splits off into the runners, which are the narrow tubes that run into the cylinder head to each cylinder.

Todd

[Peter J. Bierman]

I'm at the point where I start to do some head/intake porting / pollishing on the 6.5 heads I have lying around for the TTD engine.
Any pictures or advice would be welcome.

E-mail me at pjbierman@wanadoo.nl

Both crane and the Diesel Depot make special cams for the 6.2 and 6.5

Peter

[arrowheadracing]

I couldnt figure out how to get pictures posted here, but if you want I can share some pictures of what I have done for my personal truck. Just email service@customizedcreations.net and I ll send them off to you. Its really not that hard to improve the flow. But you have to do more then just increase the diameter an inch inside the inlet.

Good luck and I am sure you ll be happy when your done
Todd