porting a k24de head for turbo

[jbracy7]

i want to do it so bad. but i have some problems. i have tried todo it before.and just blew a head gasket.i need some one more exp on removing cast imperections and flow dynamics to school me. there are write ups on here but none for turbo ka's. like how much and where to remove/ grind .polish here dont polish there and such. thank a ton later

[480sx]

Just do a gasket match, and maybe a mild polish.

IMO a DIY port job can end up really fked up really fast. Not worth the risk. Your only talking marginal HP gains under 350 or so HP anyway, and you have the chance to really screw up your engines power balance between each cylinder.

[jbracy7]

thats what happened the first time thats why i need help. i want more boost but i need a better flowing top end first. the bottom is built up with rods,wrist pins,o rings .0136 over port job. and i'm still grinding on 215hp/187.9flbs my weakest point is the top end.i even have some cams lying around but there a lil bit to wild for myset-up right now help please

[480sx]

Why do you think you need a better flowing head dude, most people hit 300+ hp without doing any headwork at all..

Are you boosted now?

[jbracy7]

yes boosted now. i'mlooking for more torque higher in the rpm band than higher horse power

[480sx]

Turn up the freaken boost dude, or get a bigger turbo.

A port job is a waist at 200 hp.

[WDRacing]

More power in the upper rpms requires cams, not a port/polish job. A gasket match is going to be your best bet.

Here's the KAT head porting thread you said didn't exist Was in the FAQ

zerothread?id=162991

[eazye2000]

Not that I know what I'm doing, but the thread I posted a while back on porting and polishing went pretty well. Got a lot of compliments, and so far, so good.I don't have cams, and my car runs circles around 80% of any production cars that I've run into so far. I gasket matched, and removed casting imperfections. That's about it. Didn't open it up too far.Search around for it. It's got pretty good pictures too.

[jbracy7]

thanks guys all info will be abused

[D-UNIT]

The new Turbo magazine has a great article on building the KA's head. Port polishing , valve sizing , lifters , springs etc. They are shooting for 750hp on a KA. Lots of good before and after pics down the ports too.

[jbracy7]

i didnt say it didnt exist. i said theres not one for a boosted ka. and i am as high on boost as i can go with out my 200k+mile ka going boom. short of finding a new motor theres not much i can do

[nissanfanatic]

I'm willing to bet you are nowhere near the limit of your stock KA.

Where you make power in the RPM range is more complicated than just porting the head and switching cams. It is a factor of acoustics in the intake and exhaust manifold, cam timing, port size(not just as big as you can go) and numerous other things. Making top end power may work at one power level, but suck at another. Air flows though a certain size orifice efficiently at certain flow rates, but not others. Trying to shove too much air through a small hole only creates turbulence. Shoving too little air through too large of an orifice also creates turbulence. At certain flow rates, you get completely laminar flow which yields peak VE. The acoustics come in due to the frequency created by the engine operating. Each valve opening and closing creates noise. Noise is essentially air movement/vibrations. So basically, a certain size box(manifold in this case) will resonate at a certain frequency. This is basically when air only travels forward(laminar) as the vale opens and closes. Upon closure, the air packs into itself like people in line to see naked chicks. At that very moment, the valve will open and allow this air to rush in. Acoustics can explain this through the helmholtz theory/formula. It is very similar to designing speaker boxes for good sound quality. You can also think of this air movement as a sine wave, because thats essentially what it is.

The surface friction coefficient and design can also play a factor in how well the manifold performs. Dictating where you want laminar and turbulent boundary layers can be tricky. Flow benches or possibly water tesing can show what is going to happen in operation. In some areas, a turbulent boundary layer may help with transition and avoid flow separation, whereas in straight shot areas, a laminar boundary layer will prevail. Inducing these boundary layers can be done using different friction coefficients on the surface. Proper transition throughout the design will prevent stagnation points which may create turbulence. Aggressive transitions can results in laminar bubbles, which essentially is space taken up by stagnant air. Fuel puddling can occur here, not to mention, that is air not traveling into the combustion chamber to be combined with fuel and ignited.

Lots of work goes into designing a good manifold.

[neverlift]

i didnt say it didnt exist. i said theres not one for a boosted ka. and i am as high on boost as i can go with out my 200k+mile ka going boom. short of finding a new motor theres not much i can do

um, why woudl you want to rev the piss out of your"200k ka going boom" and that sounds like the plan, a ka wasnt designed to rev uber high, nor make big power up there, you need some cams, and no more then a gasket match, and clean up the runners

the guy above my post makes over 500whp with a stock ish ka

[WDRacing]

What Cory was basically saying is there is NO need to go overboard here. Clean up the casting defects, port match everything and use bigger cams that allow for more airflow. That's all that is really needed to make the KA flow "better" then it does in stock trim. Unless you're having a pro port/polish done then just improving upon the stock parts will be do a great job.

The best bet IMO if you have some money and want to capitalize your stock I/H/E is to send them to extrude hone. The method they use only removes material from the places that have the highest restriction and smooths the rest.

WD

[jbracy7]

thanks for straighting my out guys i get it now. ill check prices in my area for places that do extrude honing, i'm done trying to do port jobs my self

[WDRacing]

I had a spare RB20 head when I started porting stuff myself. It's really not that hard to do a clean up and port match. But changing the shape and or opening up the runner needs to be done by someone with experience.

[BigMACKenzie]

Port and polish jobs are a strange, weird voodoo-eseque art and usually require some rather special sauce to get done right. its usually one of those things that gets taught to you as opposed to just looking it up in a book somewhere. I agree with the others though, you are about %50 into what the stock stuff can handle, push it a little further before you get into big time/money projects like this one.