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  1. #1
    dnielsen's Avatar
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    Head Flow Testing

    I need a donor head for a project. Looking for an old 4-Tec head thats maybe damaged that someone is willing to donate to a good cause. I went out to Mike Steels racing shop today and spent about two hours with him going over some of his porting and testing methods. This guy is the guru of head porting and after looking at some of the work posted in the forum he seems pretty confident he can improve flow dramatically. The guy has been doing this type work for over 30 years and is considered one of the top porting specialist in the country. He was able to demonstrate some of the suttle changes in the exaust and how big a difference it makes in the flow numbers.

    Check out his site below,
    http://www.nitrousshop.com/custom.html


  2. #2
    dnielsen's Avatar
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    Before I start getting a ton of PMs let me clarify a couple things from my previous post. We looked at some of the porting work on the forum and he had no negative comments on the ones we looked at. He simply sees areas that could be improved a bit, in some areas by even adding material to the OEM cores. This could only be verified by making suddle changes and then flow testing. They guy is very maticulous, could take a week to do one chamber.

  3. #3
    Eastside Powersports Slow 91's Avatar
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    Quote Originally Posted by dnielsen View Post
    Before I start getting a ton of PMs let me clarify a couple things from my previous post. We looked at some of the porting work on the forum and he had no negative comments on the ones we looked at. He simply sees areas that could be improved a bit, in some areas by even adding material to the OEM cores. This could only be verified by making suddle changes and then flow testing. They guy is very maticulous, could take a week to do one chamber.

    im actually working on a cylinder head for duke right now that is going to be my most involved and time consuming cylinder head to date. I have recorded before CFM flow numbers, and everytime i made a change to the port/chamber i have re- flow tested it and recorded those gains, im over 20 hours of porting time right now, and still have to install the larger exhaust seats and valves. There are a few of my very early ported heads that i did that were not as high flowing as the ones i do now, because i was being very careful as to not take alot of material off in the wrong areas and/or port through to a water jacket. i have actually contacted a couple people ( that i can remember) and told them i would update their heads with the newest porting program the next time they had their head off the ski.

    The problem with alot of porting shops ( not saying anything directed towards your friend Donnie) Is that they think bigger = more CFM gains, which is not always the case. On the early Mitubishi engines i have actually welded the floor of the intake port and closed off a decent amount and re-shaped the port and saw serious gains on the flow bench and there was hardly any turbulence compared to the stock port.

    If you ever need any information to help your project give me a ring. I will help out in any way i can.

  4. #4
    dnielsen's Avatar
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    Your comments are in line with his way of thinking with the exception of gained CFMs through the head. Are you suggesting that the head can flow too well? I can see this becoming an issue if not funneled correctly through the exaust. It was also noted that there were issues with the heads design, specifically in the location of the valves. They sit right next to the bores causing a significant increase in flow turbulence. This may be a trade off due to the room needed for four valves per cylinder and the room needed to accomidate larger valves.

    I really dont think there is anyone better at porting heads than Mike, maybe some equal (friend or no friend).

  5. #5
    Eastside Powersports Slow 91's Avatar
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    Quote Originally Posted by dnielsen View Post
    Your comments are in line with his way of thinking with the exception of gained CFMs through the head. Are you suggesting that the head can flow too well? I can see this becoming an issue if not funneled correctly through the exaust. It was also noted that there were issues with the heads design, specifically in the location of the valves. They sit right next to the bores causing a significant increase in flow turbulence. This may be a trade off due to the room needed for four valves per cylinder and the room needed to accomidate larger valves.

    I really dont think there is anyone better at porting heads than Mike, maybe some equal (friend or no friend).
    I had a junk cylinder head that was given to me a few months ago. I ported the thing so the exhaust ports were HUGE, and i noticed an extreme amount of turbulance, ALOT of dead areas. If you over port a head, you lose airspeed and velocity. This is why alot of new heads dont have huge ports, they have a very nice and smooth radius.

    This is what i have noticed on huge port 4 tec's

    1) Bad idle, lopes like it has a cam.
    2) Throttle response is non existant
    3)Transition from part throttle to WOT isnt crisp, its very choppy
    4) Recovering from comming un-hooked is bad, ski falls on its face ( almost like a bog)

  6. #6
    dnielsen's Avatar
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    Quote Originally Posted by Slow 91 View Post
    I had a junk cylinder head that was given to me a few months ago. I ported the thing so the exhaust ports were HUGE, and i noticed an extreme amount of turbulance, ALOT of dead areas. If you over port a head, you lose airspeed and velocity. This is why alot of new heads dont have huge ports, they have a very nice and smooth radius.

    This is what i have noticed on huge port 4 tec's

    1) Bad idle, lopes like it has a cam.
    2) Throttle response is non existant
    3)Transition from part throttle to WOT isnt crisp, its very choppy
    4) Recovering from comming un-hooked is bad, ski falls on its face ( almost like a bog)
    Yep, these are some of the exact things we discussed. However if you can port the head to the extreme most point without the turbulance you will gain HP (providing the exaust and intake are adequate). One of the biggest hurdles to overcome is the allignment of the exaust tubes and the close proximity of the exaust ports to the hull (not enough straight before having to make a turn). Your right, the trick is to get the head to flow at max CFM without the air bouncing around as it passes through. The next time you have one on the machine testing try holding a short 4-5" peice of pipe over the exaust port while watching the differences in the CFMs. Then try sliding it around just a bit over the port and watch what happens (You better wear a pair of leather gloves as it will get hot as hell quick). You can find the turbulance very easily using a small metal rod with a small string attached, this allows you to see the direction of the air as it passes through the head. When doing the test porting he uses an assortment of clays and epoxys to change and mold the openings in areas based on his experience, tests and retests throughout the process while recording suddle changes. He also does this while experimenting with different custom valve setups (The valves can be made to order depending on the specifications supplied). Valve/Valve Seat angle is also as important as porting the heads, he has told me the angles that flow best for him during his years of research.

    Anyway enough rambling, we may just have to bite the bullet and buy a new OEM head to cut up! Have you got any recent flow numbers for your latest portings? OEM vs. Yours. I know I remember seeing huge gains from your work before. I can tell ya that I am completely happy with the work you did on my head, it performs very well.

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