Head flow data from basic street/strip porting

[Jason84NA2T]

This is now available on my headwork page here:

http://www.redz31.com/pages/headwork.html

This port work was done by me and then improved upon on the exhaust side by a local engine builder with many years of experience doing custom ported cylinder heads. The difference was visually massive, but I'm not entirely sure how the flow was enhanced. Regardless (and curious), I gave him another set of heads for another VG I was building and asked for flow data on both intake and exhaust before and after porting. I had hoped for finer increments from .100 to .500 valve lift (about as much lift as people run on VG's) but flow bench time is very expensive. For a turbocharged vehicle you should [b]pay particular attention to the exhaust flow. Think about it this way: the engine is being force fed its intake air, it still has to expel the additional exhaust gasses itself, robbing power.

These numbers can be improved upon with further modification. This is a basic "Street/Strip" porting job:







Graphical images created from flow data (in CFM) shown below.

13% peak additional intake flow, 17% peak additional exhaust flow
The interesting thing to note is no loss (and in fact a gain) of flow at .100" and .200" We can assume our very low lift flow numbers did not change much, if at all.

[Shen_VG30ET]

thanks for posting as always jason. good stuff to know when your heading in to have port work done. newb question. what sort of numbers would you expect on a stock engine with ported heads

[j30_vg33et]

Are the pictures on the web page of the ported heads who's data is shown? I'm interested in what the (ported) ports look like.

MK

[Jason84NA2T]

j30_vg33et wrote: Are the pictures on the web page of the ported heads who's data is shown? I'm interested in what the (ported) ports look like.

MK

I don't have flowbench data on those heads shown above the flow data. As I said, those were another set I gave him for another engine I am building. I'll take some pictures of the heads/ports that generated these flow numbers sometime soon.

[AzureblueZ]

Thanks for posting the flow data - it is always interesting to see actual results as opposed to heresay :wink:

[mario88ss]

Great info. thanks

[OR-Zman]

Very good info there. Again, thanks for the quantified info. I will be needing that on the next engine build which is forecast for this spring. NA of course...why change MO. 8)

[SATAN]

You say basic street/strip port job. what does that mean exactly? did he touch the valve guides? did he increase port diameter at all or just "shape" the ports and smooth them out?

[Dave88SS]

Just curious: is that flow per head?

An observation from the page you linked, you labelled the exhaust valve pic as intake. I think the Ferrea and Nissan valves are swapped L/R in the pic as well (based on the profile).

Awesome job, someday I hope to take advantage of all the knowledge on this site

[Jason84NA2T]

Dave88SS wrote: Just curious: is that flow per head?

An observation from the page you linked, you labelled the exhaust valve pic as intake. I think the Ferrea and Nissan valves are swapped L/R in the pic as well (based on the profile).

It's total flow of the individual intake/exhaust ports.

Thanks, I got that fixed!

[JK]

I can't seem to figure out how to bring up Satan's post, but in answer to the question. In order to get 12-18% increase in CFM, all that is required is to remove the casting bumps, smooth the transition from valve seat to bowl and maybe soften the ridge on the short side radius. You don't want to make the port bigger. And don't touch the floor of the short side radius. You can do this in 10- 15 minutes a port. No flowbench required as long as you keep from piling up the aluminum at your feet.

[SATAN]

JK wrote: I can't seem to figure out how to bring up Satan's post, but in answer to the question. In order to get 12-18% increase in CFM, all that is required is to remove the casting bumps, smooth the transition from valve seat to bowl and maybe soften the ridge on the short side radius. You don't want to make the port bigger. And don't touch the floor of the short side radius. You can do this in 10- 15 minutes a port. No flowbench required as long as you keep from piling up the aluminum at your feet.

Oh no I was just wondering what was done in order to get those numbers. Ive allready got ported and polished heads. Extreemly ported. I no longer have valve guides protruding. I shaped the port better smoother transitions and I opened it up as far as you can go on these heads. Oh i also ported the manifolds and gaskets to match(but thats not the heads)