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The area about where the sunroof is located is also a low pressure area..there is usually a "standing wave" of high pressure above the windshield and it diminishes about a foot back from the upper edge of the windshield, creating a low pressure zone. You might vent some air out to that zone too. If you ever watch water creep up the side window of the car, while at speed, that lets you know that the compressed air from under the car is going up the side and onto the roof area...That's the reason that a lot of high speed guys put rails under the bottom of the door, to keep the air where it belongs so they can channel it out the back. .02 cents
The area about where the sunroof is located is also a low pressure area..there is usually a "standing wave" of high pressure above the windshield and it diminishes about a foot back from the upper edge of the windshield, creating a low pressure zone. You might vent some air out to that zone too. If you ever watch water creep up the side window of the car, while at speed, that lets you know that the compressed air from under the car is going up the side and onto the roof area...That's the reason that a lot of high speed guys put rails under the bottom of the door, to keep the air where it belongs so they can channel it out the back. .02 cents
Aerodynamics... it's almost like physics!!!
I never did well at physics or science or biology.
"Vent it out"... but how?
Are you sure the water on the glass isn't vortex from the side mirrors? My understanding about the lip on the side of the rocker skirt helps keep the high pressure from entering underneath the car (similar to a front splitter).
V2Rocket suggested venting out the high pressure that cools the rad & engine bay through the body. This is something I totally would do if Wilson was a race car. But on a daily... no.
Since you are building a flat bottom/undertray anyways - the hot rad air would dump between the existing car floor and the undertray (spaced away from the car floor a bit) and exit at the rear of the car.
Because of the v-mount rad and with respect to reducing air flow obstacles I will try to alter the water neck angle to the upper radiator.
By the way, there are different takes/methods to "v mount" here are 2 types:
Notice the "dam" on the sides to prevent the air going the path of least resistance.
Notice the smooth ramp the builder created to guide the air in. Beautiful car!!
Okay, before I can trust this head I need to assess the condition. Disassemble using magnet to acquire the valve retainer keepers.
I am hoping to do all of the head repairs & mods by myself. This head looks rough in a couple of areas, for instance the 2 broken studs for the water neck were severed when I got it. After attempts to weld nuts and wrench them out were unsuccessful, then I tried drilling & using easy-out removal tools (which of course did not work). Then I tried drilling through and tapping. I managed to drill an tap the bottom bolt but my drill bit broke in the upper bolt. That doesn't really matter though because I don't plan on using the top bolt hole.
Top: 8 valve neck, bottom 16 v which points to the driver's fender versus the rad.
The 16v neck isn't shaped the same where it'll meet the head unfortunately, but maybe it can be modded. Notice the spacer.
Assessing the condition. Valve surfaces shouldn't be "cupped" or worn, where the valve head seats. They should appear flat on the machined bevel. This looks like it could use a quick hand powered "valve lap" and be good to go! As each valve and spring and spacer & retainer is removed from the head, it is placed in a particular order on the bench (i.e. cyl #1 intake).
YES!! Woohoo! These intake ports have a 5 angle grind already!! This is something I wanted but was going to forgo because not in the budget. Awesome
I check the valve guide wear with the springs removed and at 10mm "lift" in the direction of wear a little play is okay. These guides are not worn out so I will reuse. The last head I had apart had twice this radial movement and the valve seat were cupped... I think worn guides wear out seats.
Some respected builder Chris White taken out from several of his responses on a thread regarding turbo head modifying.
"If you must port and polish then polish the outside of the head and buy a nice port wine and drink it.
The ‘good old days’ of porting and polishing died a while ago. The “bigger hole – more air – more power” theory does not apply. The interactions of the shape/texture/design of the intake ports and the production of power is seriously complex and, as any decent head man will tell you, not scientifically well defined.
The most important product of modern cylinder head design is the turbulence created in the combustion chamber – a pretty tough thing to measure. The propagation of the frame front can be greatly effected by the turbulence, by as much as a factor of two. The speed of propagation has every thing to do with controlling detonation and achieving favorable conditions for additional ignition timing. So if anybody thinks they can grab a die grinder and alter their ports to add turbulence to the combustion chamber good luck.
Back in the days when I helped out on the Trans Am circuit I got to see the real high dollar heads and you would swear that they wouldn’t work well. They were the result of a little science and a lot of trail and error. If you have 30 or 40 heads to experiment on (the results can only be shown on the dyno so you will need to assemble and test each engine) then you might be able to show some real improvement.
That being said – it doesn’t hurt to clean up any casting abnormalities and maybe clean up the valve guide casting area. A good valve job will get good results.
PS - the turbo may create some turbulence at the compressor but after it has traveled through the intercooler and quite a bit of piping and the throttle body the turbulence is pretty much "straightened out."
Oh yeah – one other issue on head texture – remember that at any kind of real load the fuel injector will be squirting fuel at a closed valve. 80% duty cycle refers to the injector firing for 80% of the complete 4 cycle. Batch fired systems fire twice per each 4 cycle (720 degree) occurrence. One shot will be during the intake cycle but the other one will be 180 degrees out. The texture of the walls can effect the ‘wetting’ factor. Very smooth surfaces tend to increase the amount of fuel that will come out of suspension.
Just as a point of interest – the Tec3 system even has an adjustment factor for the amount of intake port ‘wetting’. If you have a set up that really encourages intake wetting then you will see an initial lean out when opening the throttle. This is because the fuel is ‘sucked’ of the walls during a closed throttle decelerating condition and when you first crack the throttle a certain amount of fuel will drop out of suspension to rewet the walls.
Polish the outside….
Think ‘systems’ approach.
If you bolt that head on an other wise completely dead stock engine then it will not do anything ‘special’ and quite possibly drop off your low to mid range torque just a tad.
If you really want modifications, especially those directly effecting the air flow, to work you need to make sure that the ‘system’ is modified or adjusted to accommodate the mod. So if you are bolting that head on an engine that has a larger turbo, different wastegate set to a higher boost level, modified engine management then it may well make more HP.
Another thing to keep in mind when I use the catch word ‘system’ – you need to define what you want to accomplish (and ‘more performance is not an acceptable answer!)
Defining what you want to accomplish is a very important step in modifying – and don’t take it too lightly as there are consequences for every action.
Do you want more max HP? Then you will give up low to midrange torque.
Do you want to support more boost? Then you will not have as good spool up or off boost response.
To a certain extent its all give and take, so defining your goal and understanding the implications is pretty important."
03-04-2017, 06:18 PM
This is something I wanted but was going to forgo because not in the budget. Awesome
