Ramp on TFS heads

[chilly460]

Just fiddling around with my TFS heads as it’s too hot to do real work.  Measuring out the heads to find minimum CSA and the throat size and %. 

Anyway, noticed this pretty pronounced ramp on the short side of the roof just as it’s turning into the bowl.  I’m no expert but I don’t think anyone would normally think a lump in the roof is normally a good thing.  Any theories on this?  Could it be just to shrink the port s bit and they found this was the least impactful location? 

Again, I don’t know much, only other thing I could find in a quick look was some pretty sharp edges on the short turn, almost like the cutters came in from each end of the port and met in the middle and put a little peak on the short turn.  My AFR 205s had this and knocking it down picked up 10cfm as that’s usually a pretty high velocity area. 

[chilly460]

Sorry posting from my phone and trying to figure out how to shrink the pic

[frnkeore]

After getting mine, I asked a few questions about them on Speed Talk, about 5 weeks ago. There are a lot of guys that port heads over there but, even though the heads aren't that new, no one seemed to know anything about these heads.

https://www.speed-talk.com/forum/viewtopic.php?f=1&t=63715

In the next to the last post, I gave my opinion of what the roof shape is about but, it's just a guess.

[jayb]

From what I can tell in the picture, that feature is a vane that is designed to induce swirl in the A/F charge, for better fuel atomization.  I investigated doing that on my heads when I was designing them, and I still might do a few that way just to test them, now that I have some base dyno data on the existing heads.  The interesting thing about a feature like that is that if it is designed correctly, it really doesn't impact the flow of the heads, so grinding it out and smoothing it, like some shops would want to do, won't help the flow, and probably will hurt the fuel atomization.

[chilly460]

Jay, that was my thought as well, it's for swirl.  The TFS have a lot going on that's unfamiliar to me, the vane in the floor being most prominent but the floor is also slanted quite heavily, and then the ramp on the roof as mentioned. 

The easy first question is if this ramp somehow helps with lower lift flow/atomization but is part of the reason they start getting noisy at .600" as several guys have reported?  As the assumption is these heads were aimed squarely at the hydraulic roller street guys, it jives that they'd maximize them up to .600".  I did my best to check the minimum CSA and came up with 2.56sqin, which according to the calculators, jives well with a 6000rpm 445-462 deal, or a 7000rpm 390....which is also .600" and below cam territory.   The throat came in a 90% of the 2.19" valve, which I understand is fairly standard, with "race" stuff pushing a bit higher with steeper seat angles for high lift. 

[MeanGene]

The S&S heads on my Indian have a very pronounced vane in front of the guide, they have been made that way for a long time and they flow very well. In fact with a 240/560 cam, it makes 97hp/98tq at the rear wheel from 88 ci with just the cam change, stepped pipes and my own timing curve- has never had any problem smoking 95ci Screechin' Chicken Twinkies when that was the hot Hardley Dangerous setup. And it makes 84tq all the way down at 2500. This is the dealership shop foreman when we had it on the chassis dyno in the next room- the stainless stepped Swoops pipes are kinda loud lol

[67xr7cat]

First time saw a vane on a port floor was on an iron 4V Cleveland head from a Nascar team back in 1989. Purpose is to re-direct the flow and sometimes to get it off the floor.  When a port goes turbulent usually is flow separation meaning does not make the turn. Working the short turn probably will help, but without a flow bench is hard to know if a change helped or hurts. Even then like Kaase would say if it works on the flow bench I dyno it, if it works on the dyno, I run it at the track, if go slower I unplug the flow bench.   

IMHO the TFS head is targeted for the street/strip crowd so strong mid lift focus makes sense. 

[4twennyAint]

Most other modern cylinder head developers use CFD software (Computational Fluid Dynamics) to create killer port designs.  Leave it alone.