Is it a black art or is there some fluid dynamics science applied?

if you are unfamiliar with terms used in head porting and want pics and definitions for basics, please check out this site first. I found it helpful even though it relates to domestics:

http://www.sa-motorsports.com/diyport.htm

Okay so I have some time on my hands and thought we could look at some comparative porting and invite members comments and experiences:DPR and Endyn headwork. Why these 2? They have different porting philosophies. DPR is where Tom at Portflow got his experience and so his work is derivative of the DPR approach. Please look at the port volume (where and how much material has been removed on the ports), port shape, injector and valve guide area work, quench area modifications to the bowl, and valve seat area (including seat angles).

DPR believes in optimising low intake valve lift (< 33% lift) flow. Endyn does not and believes the majority of reversion occurs at low intake valve lift : they negate any flow at low valve lift. So, the angle valve jobs are different in approach. What about the intake ports? DPR uses the classic porting approach from domestics focusing on the short turn radius and roof porting without taking what they consider too much off...how much is too much (hogging out the ports) ? by trial and error, and doing tons of heads. DPR has interpolated by experience how much material to take off. Endyn focuses only on the floor, fills in the injector slots, and uses what they call turbulator dimples to atomise the fuel. DPR uses the classic cloverleaf combustion chamber shape to get more quench and weld on material to the head. Endyn spot faces and optimises quench area without using welded on material to get a cloverleaf. There's more but I won't get into it until we get other input.

I've collected some pics on the net comparing DPR porting vs Endyn head porting. These are not my photos and so I had no control over the angle of the photo or magnification. Thanks to Tbone for sharing his DPR head pics. The Endyn pics are from their website.

The convention here will be DPR first then Endyn (alphabetical order...no bias)

DECKS





INTAKE PORT





EXHAUST PORT





COMBUSTION CHAMBER





I know TypeRmsm had his porting done by another porter. There are some folks with porting by other shops. Please post them so we can compare. So here we go....let's hear your opinions...thoughts on which works better and how much power just from the had did you get? how about costs? customer service?

cheers




[Modified by Michael Delaney, 1:45 PM 12/4/2001]

 

Fix the last pic and the exhaust port pic(one is an intake port)

 

how much is DPR Racing
charging for:

Stage IV: $$$
StageV: $$$
Stage VI: $$$

 

I have Klymenko Flow do my heads, Eugene Klymenko calculates what the head needs to flow etc, If you want to pick his brain some day, i'll give you his # Just IM me, Lets just say when he really starts going I just have this dumbfounded look on my face along with everyone else in the room

Here are some pics of a Klymenk Flow Head
COMBUTION CHAMBER



INTAKE PORT




EXHAUST PORT

 

it takes a little bit of both when porting heads, it takes a lot of time and patience when porting heads, then you gotta flowbench the head(s) to see if what you did to the head improved it or not....by looking at the pictures i can see that dpr has probably done a lot more r&d with their heads then endyn does. endyn's looks basiclly like a basic clean up job on the porting, which is good for a street setup. i don't know why endyn focuses on the floor of the port, as we know air moves faster at the top of the port then at the bottom thats why most porters will focus mainly on the top of the port. i don't like the fact that both of these heads have the sharp angle at the splitter in the intake port for, what i have learned was that air does not like sharp edges....i might not know everything so please correct me if i'm wrong.............

 

Larry used to say the same about his own work in jest and would bait people to come on and argue against his way of porting. A lot of what you say is pretty old school stuff. No-one really depends only on a flowbench any more. Flowbenches like dynos are not always truthful. The racers especially. I guess you either believe in reversion happening at the intake valve or you don't. You either believe in tumble fill or you believe in swirl fill. If you subscribe to the tumble theory, then the roof of the intake port needs work. If subscribe to the swirl theory, then the roof is left alone and the floor is worked on so the velocity down there is increased to keep the floor flow parallel to the roof flow (laminar)...

 

This is what i like about this board. Seems like everytime i wonder about something its posted a few days later. I'm getting ready to step up to some head work. (even purchased a spare pr3 head to minimize downtime).

My four convienent (sp) options are DPR, endyn, portflow, BCE racing heads.
The question is, who really knows their stuff? How much is this all going to cost?

More questions: valve guides-leave them alone,shape them, or grind them completely down so as not to obstuct flow? port finish- leave it rough or polish it smooth? welding- good or bad? any reliablity issues? have heard of welds coming apart and destroying engines.

What else do i really need? bigger valves, bronze guides...etc.


Sometime in the next coming months i plan on visiting each porter and seeing what they have to offer as well as compare prices.

sorry for all the questions but with a ll the different theories its hard to keep everything straight.

 

NOTE: pics of my head were taken before valve seat work was complete.( the ones without the valves )

 

If I could see the pictures with any kind of detail.......... jeez who took those???

 

Me Sorry the lighting was horrible and I just got the camera

 

Thanks for the info and ideas.
Now, how about some flow numbers, or better yet HP improvements realized through this type of head work.
Oh, and last but not least how much $$$.

One last thing, how would a forced induction head job differ from one for an N/A application? Ed

 

Regarding the valve guide issue, I have used four different cylinder heads so far, so I have experience with them all.. but unfortunately they were not all on the same motor so I am not able to give a DIRECT comparison as to which is best.

I've has
1-Topspeed
2-Endyn
3-Portflow
4-Autosport South

The valve guides were kept 100% intact by both Portflow and Endyn. Portflow *slightly* grinded down the exhaust valve guide, but not more than 1 or 2mm, and he smoothed it out as well.
Topspeed Performance gets rid of the valve guide completely, in the part where it protrudes into the ports(intake and exhaust). Regarding the issue of premature guide wear, Josh told me he has never had any problems with guide wear, and on a cylinder head he did over a year and a half ago, he measured it. Using a ball gauge to measure the ID of the guides at the top by where the seat seals, and at the bottom where it comes into the port, it showed no unusual wear than any other cylinder head. All the clearances were identical to those compared to a 40,000 mile B18C1 head.
The Autosport head, was not actually a "paid for" head job. I purchased a used ITR head off the owner of the shop, and it came off his race car. He did a mild port and polish and some slight combustion chamber work. By the looks of it, all he did was take the OEM port job on the ITR a step further. Gains were seen on my motor at the time.
It was a B18C1 block w/81.25mm bore B16A pistons, Spoon cams, DC header and ITR head. By switching to this head and tuning the cam gears I gained a peak of 4hp and a constant 3-5 in the midrange. Decent power for the miminal work done to the head. Looking back, I can easily say that any DIY mechanic can do this minor porting on his own.

Regarding performance, I have seen the greatest results with the Topspeed headwork. Now, this is not saying that Endyn, Portflow or Autosport suck.. which they DON'T. It's just that I had the opportunity to install and tune a Topspeed head on a B18C5 motor before and after. The results were no bullshit. I can tell you so because I tuned the car. You can email Josh for the dyno sheet, he can be reached at j.n.holcombe@worldnet.att.net
Ask him for Chris' dyno sheet.

It was a B18C5 w/ stock cams, JDM 4-1 and CTR pistons. Peak gains were about 13hp in the midrange(with help of V-AFC tuning), and peak went from about 180 to 189 if my memory serves me correct.

Portflow heads are very similar to Topspeed heads. I think the only true advantage(if you wanna call it that) is the valve job that Portflow gives. And that in itself in an unfair advantage, because Josh sublets out the valve job to the local machine shop. He does the porting, and the machine shop across the street does the valve job and mill.

Keep this discussion going. I like posts like this. Lotsa good info.

 

hello, nice post and nice pics of those ported heads ... I have some even nicer, clearer pics too


Greg

 

Yawol Mein Kommandant! Zeig Heil! (What am I? Schultz from Hogan's Heroes?)


[Modified by Michael Delaney, 1:09 PM 12/4/2001]

 

To clarify: I put up this post so we can use it as an educational tool not as an attack on any one approach. I appreciate Tom sending me his pics to post up and it was done so on the premise that we don't attack the work.

If you look at how much Klymenko removes and his port volume compared to DPR's or Endyn's (especially in the exhaust port): it looks like Klymenko removes more material all around.

Mike (TypeRmsm), please don't take this the wrong way. My question is : Is the powerband peaky and narrower compared to pre-porting?

MikeK : thanks for sharing your experience. You raise a very important point -where is the most gain and how wide is the powerband? When people quote gains they definitely place emphasis on peak gains but don't mention any aspect of driveability. You hear 15-20 whp gains but do we assume that's peak? Would people be disappointed with an 8 peak whp gain for headwork realizing they got 15 whp in the midrange?

I think we touched on this before but I'll re-iterate it: what discussions did you have with your porter before he started work? I think you have to mention displacement, redline, cam profile, manifold plenum and runner size, TB size, header layout and primaries diameter/length, all motor/forced induction, daily driver vs trailer queen, octane, where you expect the power gain to be and how wide....did I miss anything? Sizing the port volume and shaping the ports can only be based on this info.

There is a statement by Endyn that the main gains in head porting are made in the seat angles, deshrouding the valves, and improving quench area. NOT AT THE PORTS. He says that the main porting done by Honda's top porters on the ITR out of the factory is mainly at the bowl area around the valve seat. Is this your experience? If so, would it not be more cost effective for a high performance streer/occasional weekend racer to have a 3 angle valve job and clean up the bowl area/quench area instead of a complete port work, 5 angle valve job, etc.?

3 angle vs 5 angle valve jobs: Is there a big difference? or are you spending more cash to have the Serdi work longer for minimal differences?

Oversized valves and stainless steel valves: are they worth the extra cash? Oversized valves is a trickle down from domestics and tends to make the engine peaky with a narrow powerband. Stainless does not afford a noticeable gain in hp for the cost and the valvetrain weight savings is more hype (Titanium is another story but is not durable for the street)....are these comments true?

How many people switched to silicone bronze valve guides with stainless steel valves due to metallurgical hardness incompatibility between stainless and the stock valve guides? How many people replaced their valve guides altogether with headporting?

Those turbulator dimples on the Endyn intake port entrance up top: supposed to help atomise fuel better. He also alters the injector slot shape for the same reason...is this a big deal? or marketing?

Greg: would love to see your clear pics.

Just to put some context on the pics: Endyn posted these pics as "B18C5 road racing" head and I think Tom's pics of his DPR head are more for a high performance street application.

Keep it coming guys....

cheers


[Modified by Michael Delaney, 9:37 AM 12/4/2001]

 

Can we start a "saved thread" section? This is an interesting post that I would like to see perpetuated in the future through further discussion and debate.

 

hello, both guys do extremely good work and bring tons of experience to the table, I have heads done by both portflow and endyne which I use for my personal cars.

Pics of my head(s) ?
naaa, thats ok

btw, you've seen my head you just didn't realize it, thats all.

Greg

 

I've asked for that a long time ago. It would be very nice to have something like that available. The search could be used much more efficiently.

SMSP- Who's got 3 spare heads now and who may personally just try to port each one a little different....

 

wrt using flow bench numbers: this was a very nice read
http://www.rehermorrison.com/techTalk/16.htm

In most cases, people use inlet to outlet cubic feet per min. (cfm) relationships and hp to cfm relationships at various vacuum pressures and displacement to describe how the ports should be done.

air fuel mix quality during filling, cam or valve timing, and header/exhaust sizing and layout will affect whether the wet flow bench numbers mean anything in reality. The number kicked around for normally aspirated engines is that exhaust cfm should be around 70-80% of inlet cfm but no one rule is true for all circumstances and at all rpms...midrange rpm vs peak rpm. Secondly, some people kick up the formula of hp vs cfm:

Potential hp = [0.43 x cfm @ 10 in. water] x no. of cylinders or
[0.256 x cfm @ 28 in. water] x no. of cylinders
http://www.racetech.com.au/custom.htm

This is why the flow bench alone is no longer the yardstick by which we grade porting work.

I think it would interesting to get some motorcycle racing head porter's views since they deal with low displacement engines that rev to at least 9000 rpm. I've seen motorcycle heads with D shaped ports and they work amazingly well. Port shape and smaller port volume are the general rules for import engines. But is this where head porting makes power? probably not.
http://www.650motorcycles.com/XShead.html

cheers

 

I personally have used Topspeed and was very happy. At first I was a little weary about having the valve guides hacked off but then I also realized that the car was not going to be driven 200,000 miles nor should I expect it to with loose clearances. I installed it on the car with the Skunk2 Manifold they did for me and I am very happy. We are still breaking the motor in, but from 1k-4k rpms that we have traveled you can tell that there is definatley extra power there and it feels better than some of the 185-195 motors that I have driven. Once the car is broken in I should be posting dyno results. I would recomend Josh to those who want a good port, especially if your in FL as the turnaround is mucher better than shipping it to Cali.

 

This is a good thread. I don't want to see this thing turn into a pissing contest with which head is better than which.

Regarding valve jobs, I don't think there is much gain to be had from a 3 angle to a 5 angle valve job. Just make sure you get the intake valves back-cut. I KNOW this improves flow greatly.

My friend used bronze valve guides, but only because all his old ones were shot and the price was comparable to new OEM guides. Not sure what kind of gain can be had from this either.

 

I have pics of Portflow's designs just need to look for them .. long story but I had them in photoshoot then they shut my account down because I wouldn;t join and lost everything so now I need ot put on my website... as if I have the time to do so.

I think Tom actually brings his experience from his Nissan gtp days, not sure if he gained any kind of experience from DPR, thats what he says anyway.

cfm by RPM is one variable, but the true magic comes from swirl technology. See if you can find more info about the BCE headwork, he incorporates some good technology also, just never used him.

Greg

 

I think if the job is done properly a 3 angle valve job would do the trick, expecially at the last concentric angle. Are back-cut valves matched to the last seat angle or is it a multiple cut for multiple angles? Once again, we have a difference in approach:

DPR back cut my intake valves in an effort to gain some low to mid lift flow. They believe that at maximum lift, no one can improve on the factory's work and the head flows really well there. So the gain in inlet flow is targeted to the low-mid lift areas. If you have Joe Pettitt's Volume 1 High Perfrmance Honda Builder's Handbook, the chapter on cylinder heads goes into this in more detail. Whether Portflow believes in improving low-mid lift flow with their seat angles and back of the valves, I don't know.

Endyn is a completely opposite story. He puts in a big step at the last concentric seat angle and has a single back cut on his valves all in an effort to have no flow forwards or backwards at low intake valve lift. The theory here is that during the exhaust stroke, the exhaust and combustion chamber pressure is much greater than in the intake port and intake manifold runner. So as the intake valve starts to open at overlap during the exhaust stroke, you will get back flow into the intake runner causing a detrimental dilution of your fresh intake charge. He uses valve timing to kick open the intake valve at 12 degrees ATDC instead to get his necessary intake flow.

You may want to replace your valve guides in the porting process. I was told by the Jun boys that stainless steel valves are incompatible with stock valveguides because they are too hard and would wear out the guides fast. The bronze valve guides was their suggestion and since they sell them I'm not sure if it was marketing or reality.

Lost Motion Devices: When you send off the head to the porter, please check if these are all there. I hear a lot heads get sent for work and then when they are returned there's complaints of a rattling noise when VTEC is engaged. Either the LMD's fell off after work or were never replaced when they arrived to the shop.

Welding on material to the combustion chamber (eg. DPR stage VI): Endyn advises against this unless the shop doing it has a lot of experience and cools the head properly at a controlled set rate so there's no mismatch between the new material and the head. Otherwise you have a structurally weaker head. I assume Dan's been doing this for ages and knows how to do it properly, so I won't dwell on the topic. Whether other porters know how to do this is another story.

Flow matching the head to the cams: I caught a lot of flak from Frank Lin on posting this awhile back. Ironically I got the calculation of how to flow match the head to the cam redline from HIS site in HIS archive! I think Dan has a table that flow matches his heads to the cams you use based on their intended valve timing and redline...I'm not sure on this though. The flow bench is not our only indicator.

b16a/b18c5 head vs b18c1 head: more direct shot in the GSR head and it has better flow numbers on the flow bench. b16a/b18c5 has lower flow numbers on the bench but "flow quality to properly fill the combustion chamber" is better...whatever that means.....

cheers

 

Agree with you 100% about the lost motions. We send a customers head of to a reputable shop and it came back, we installed it and it was screwed up. Lost motion assemblies where the problem.

 

Tom,

I was looking more at the quench areas and unshrouding of the valves in these pics. But you are right, the valve seats , bowl blending into the seats, and short turn radii can be looked at, at least in the Endyn pics anyway.

cheers