lowlancer Posted June 4, 2007 Author Share Posted June 4, 2007 Matched to manifold eh? My manifolds are a LOT bigger so shouldn't be a worry exhaust wise. Might hve to look at inlet stz Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 4, 2007 Share Posted June 4, 2007 from what ive seen theres alot less science involved than people think, it only gets really scientific when you start doing stuff that messes with the compression rather than flow. thats a random statement theres more science going on to describe the flow than you could shake a stick at. Quote Link to comment Share on other sites More sharing options...
thminiman Posted June 4, 2007 Share Posted June 4, 2007 from what ive seen theres alot less science involved than people think, it only gets really scientific when you start doing stuff that messes with the compression rather than flow. thats a random statement theres more science going on to describe the flow than you could shake a stick at. was fucken vaige as etc due to my laziness Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted June 4, 2007 Share Posted June 4, 2007 Matched to manifold eh? My manifolds are a LOT bigger so shouldn't be a worry exhaust wise. Might hve to look at inlet stz Mine were only about 2mm bigger. Look on the net for a guide to your specific head too. Like mine you have to watch for the waterway under the ex ports. Saves ruining it eh. What sort of head you doing 4g63? Quote Link to comment Share on other sites More sharing options...
Roman Posted June 4, 2007 Share Posted June 4, 2007 nobody who is serious about modifing heads polishes intake ports thesedays. Polishing is out boys it's been proven. This isn't just for carbed heads who don't want the fuel slicking to the polished intake. But also for injection as the air doesn't flow as well through polished surfaces. Tis true believe it or not. Every factory engine that I've seen which makes ~100+hp per litre has smooth ports, and intake manifolds with smooth surfaces too. The rough surface is merely a byproduct of the casting technique in mass production. (in my opinion.....)cleaning up the surfaces is not cost effective in mass production. 'special' mass production engines get this treatment. Which makes me think that it's a cost/benefit reason more than anything. B18CR & F20C honda engines for example, which make over 100-120hp per litre have port & polish jobs, done by hand in the factory, specifically to clean up the rough surfaces etc. Otherwise, why wouldnt they just cast the head into a slightly different shape? rather than casting it, and then drilling extra out.... Many people who think that there are big gains to be had from going to a quad throttle setup, probably do get gains from a quad throttle setup. But only because their factory single TB manifold is so shit, with rough castings etc. I doubt I'd get any HP gains with a quad throttle setup, seeing as how the engine already has (smooth) steel intake runners with bellmouths on the ends, inside the (smooth) pressed steel plenum, leading to smooth ports. If I had a nasty cast intake manifold, then I'd either look at binning it, or smoothing it out somehow, Because lets keep things in perspective... Porting the head isnt going to do shit, if your intake manifold is utter crap. The only way to really get some gains is to treat the head and intake manifold as one functioning unit, and alter the head/intake runners in conjunction with each other. Perfectly flowing ports are no good if your intake runners are half the cross sectional area, and you're stalling the air just at the point where it should have maximum velocity! also, opening up intake ports doesn't always mean good things, bigger is certainly not better in many cases you loose velocity. Serious modifiers even close up the ports in some cases. Quoted for mother fucking truth! Quote Link to comment Share on other sites More sharing options...
RT Posted June 4, 2007 Share Posted June 4, 2007 I think we might be talking about two different things here. 1. Cleaning up the ports by removing casting marks is always a good thing to do but best to leave the surface slightly rough. 2. Polishing up the intake system to a smooth finish on the other hand is what I was referring to & not a good thing. simply because you have seen some decent powered engines with polished ports doesn't justify their existance, perhaps if they were not polished they might flow even better! Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 4, 2007 Share Posted June 4, 2007 The reason people went away from polishing ports is that research in to boundry layer flow found that the air sticks to the polished Port wall and there is a shear effect that narrows the usable flow area in the port. With a good stone finish 90 degrees to the air flow there are tiny ridges that cause localised turblence on the port wall, this has the effect of making air bearings that the main flow can roll over..... same idea as a golf ball. I'll dig up some links tomorrow.... Quote Link to comment Share on other sites More sharing options...
Roman Posted June 4, 2007 Share Posted June 4, 2007 I think we might be talking about two different things here.1. Cleaning up the ports by removing casting marks is always a good thing to do but best to leave the surface slightly rough. 2. Polishing up the intake system to a smooth finish on the other hand is what I was referring to & not a good thing. simply because you have seen some decent powered engines with polished ports doesn't justify their existance, perhaps if they were not polished they might flow even better! Aaah yep, I think that what you're saying is one of the major problems with the car 'tuning' scene. For example. Tuning company A takes a massive engine, and stuffs it into a little car. There isnt any room left for the standard intake piping etc, so the simplest solution is to bung a pod filter on the end. People think "omg that car makes 400hp and it's got a pod filter, I've gotta get one too!" When the pod filter is a solution to a problem, rather than being the cause of an HP increase. But what I'm saying is, honda have brilliant engineering when it comes to high strung NA engines, and they opt to take the cost of porting/polishing on board for their limited production high HP engines... and they've been in the game for a long time and definitely know their shit. Although in saying this, it does bring up an interesting point. Perhaps some rough cast heads are designed with port sizes etc to take this into account. EG a large port with rough edges etc will have an effective reduced diameter thanks to turbulence etc, if you smooth off the bumps, then you've (perhaps) increased the cross sectional area of effective flow by a massive amount, and dropped the intake velocity a whole lot. I suppose (like most things) that it's dependant on the particular engine that you're working with. I definitely wouldnt base my conclusions on joe blow down the road with a dremel, saying he gained 40hp by polishing his ports (among other things) The reason people went away from polishing ports is that research in to boundry layer flow found that the air sticks to the polished Port wall and there is a shear effect that narrows the usable flow area in the port. With a good stone finish 90 degrees to the air flow there are tiny ridges that cause localised turblence on the port wall, this has the effect of making air bearings that the main flow can roll over..... same idea as a golf ball. I'll dig up some links tomorrow.... Interesting, I think I've heard something along these lines before. But It's also interesting that a lot of the high hp/litre engines have smooth ports from factory, and they're hardly 50 year old engines or made by morons either.... Quote Link to comment Share on other sites More sharing options...
Hemi Posted June 4, 2007 Share Posted June 4, 2007 heard pod filters are bad for afm's somthing bout burning them out? Quote Link to comment Share on other sites More sharing options...
Roman Posted June 4, 2007 Share Posted June 4, 2007 Depends, if you had an 'oiled' pod filter and a hotwire AFM, I could see that possibly doing some damage.... Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 4, 2007 Share Posted June 4, 2007 Interesting, I think I've heard something along these lines before. But It's also interesting that a lot of the high hp/litre engines have smooth ports from factory, and they're hardly 50 year old engines or made by morons either.... Smooth or polished? Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 4, 2007 Share Posted June 4, 2007 Here's the golf ball theory.... Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 4, 2007 Share Posted June 4, 2007 People think "omg that car makes 400hp and it's got a pod filter, I've gotta get one too!" When the pod filter is a solution to a problem, rather than being the cause of an HP increase. But what I'm saying is, honda have brilliant engineering when it comes to high strung NA engines, and they opt to take the cost of porting/polishing on board for their limited production high HP engines... and they've been in the game for a long time and definitely know their shit. You do realise you are saying omg "that car makes 400hp and it's got polished ports" Although in saying this, it does bring up an interesting point. Perhaps some rough cast heads are designed with port sizes etc to take this into account. EG a large port with rough edges etc will have an effective reduced diameter thanks to turbulence etc, if you smooth off the bumps, then you've (perhaps) increased the cross sectional area of effective flow by a massive amount, and dropped the intake velocity a whole lot. I suppose (like most things) that it's dependant on the particular engine that you're working with. BINGO! I generally work with old cast iron shit that has nasty ports, the pinto for example it's much easier to hurt the flow than increase it. Port it bigger and polish it is a great way to slow down the air velocity which means the carb will respond slower and fuel drop out can be come an issue just to start off with. Porting a head I haven't done before means first doing the research to see what's been proven to work with that head. Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 5, 2007 Share Posted June 5, 2007 By all means remove any factory castings and smooth the ports if there are any harsh angles but a modern head probably can not be much enhanced without major surgery. The short side radius is usually where the easy gains can be made and even in some moden heads... that often depends on the cast and casting method. As a genaral rule the more performace a modern engine, the less gains porting will make. Some of the modern engines are still nasty and will respond to a tickle up. In all honesty it is probably a waste of time but if you have nothing to loose it could be fun. Exactly! Port matching requires your manifolds and bearing blue. You will probably find that they are really close already. The marvels or modern Japanese engineering. Break a ball point pen in ½, pull the nib out and you have "Bogan bearing Blue" with air powered applicator (Blow the ink out of the tube) Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 5, 2007 Share Posted June 5, 2007 The short side radius is usually where the easy gains can be made and even in some moden heads... that often depends on the cast and casting method. As a genaral rule the more performace a modern engine, the less gains porting will make. Some of the modern engines are still nasty and will respond to a tickle up. Clearly we are on the same wavelength Enhancing the short turn radius is pretty hard on many heads. With certain old Ford heads a few wise men have built 'downport' heads which effectively bring the charge in on an almost straight line from above the chamber. It requires custom inlet manifolds and welding up the original ports so they are almost gone. Heat, distortion and water leaks are near impossible to eliminate. That is a lot of work Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 5, 2007 Share Posted June 5, 2007 Clearly we are on the same wavelength That would be the dirty old bogan frequency Enhancing the short turn radius is pretty hard on many heads. With certain old Ford heads a few wise men have built 'downport' heads which effectively bring the charge in on an almost straight line from above the chamber. It requires custom inlet manifolds and welding up the original ports so they are almost gone. Heat, distortion and water leaks are near impossible to eliminate. That is a lot of work There's making the best of what you have and then there's starting up the welder. I recently did RT's EB 4L head and it was alloy and had a good shape but it was still pretty much 3 flat angles making the curve. After I'd finished with it, it was a nice smooth curve..... with that and the shaping of the valve guide I'd guess I'd have been lucky to pickup any more than 5% flow though. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 5, 2007 Share Posted June 5, 2007 Randomly widening out the ports isnt going to acheive a hell of a lot. I can't quite agree. It will in all probability achieve a significant and noticable reduction in mid range power Yes - I know that's what you meant. I am just bored Quote Link to comment Share on other sites More sharing options...
Chrome_GT Posted June 5, 2007 Share Posted June 5, 2007 Yeah Nismo capri is onto it. Make it turbulent to make the flow stick around bends. Used on aircraft , golf balls and all sorts of things. Whether turbulence is a benefit or not depends on the fluid velocity though. I'm not sure how the flow velocity through head ports compares. Someone with a bit of time should look up Reynolds Numbers for ducts, ports etc and see if they find some charts. A few quick calcs and you might get a better answer. I've had people tell me the whole roughness helps vaporise thing too. However having the roughness would surely help catch the fluid in the first place too so I'm not convinced it's the reason. Anyway, equipment wise an air grinder and a decent sized compressor. My die grinder was a lot thristier than my spray gun. a 2.5hp, 50 litre isn't big enough. You'd have to keep stoping and the compressor would be charging all day. I'm pretty sure i've seen long reach grinders on TM too. Quote Link to comment Share on other sites More sharing options...
Roman Posted June 5, 2007 Share Posted June 5, 2007 You do realise you are saying omg "that car makes 400hp and it's got polished ports" No, because I lend differing amounts of credibility to what a long established maker of proven high HP engines chooses to do, and what some random 'tuning company' decides is a good idea. Not that any of this matters to me, because I know enough about heads to know that I dont know nearly enough to start playing with the ports etc. Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 5, 2007 Share Posted June 5, 2007 No, because I lend differing amounts of credibility to what a long established maker of proven high HP engines chooses to do, and what some random 'tuning company' decides is a good idea. For sure man, I was just fishing for a bite Quote Link to comment Share on other sites More sharing options...
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