kyteler Posted June 1, 2007 Share Posted June 1, 2007 Same as Romans. Not so much the total area, as it is the smoothness. Air flow disruption is ftl hard.No point having massive ports if they are rough and cause turbulence Unsure on that, I know there used to be a lot of debate about whether leaving them slightly rough (not massively) was a better bet as it broke the air up and allowed for better atomisation of the fuel into the combustion chamber. Quote Link to comment Share on other sites More sharing options...
lowlancer Posted June 1, 2007 Author Share Posted June 1, 2007 Hmm, most injector systems would atomise the fuel fine Perhaps on carb fed systems... Quote Link to comment Share on other sites More sharing options...
kyteler Posted June 1, 2007 Share Posted June 1, 2007 Aren't you going carb'd? Or are you using one of those filthy Mitsi "EFi" Carbs? Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted June 1, 2007 Share Posted June 1, 2007 fuck I'd lawl if he spent huge coin and injected it. jesus. chuck it on sidies, boe Quote Link to comment Share on other sites More sharing options...
lowlancer Posted June 1, 2007 Author Share Posted June 1, 2007 Yeah will be carby, but twin carbs, so it won't be underfuelling on individual cylinders. You make a good point though old man. Might have to research further... Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted June 1, 2007 Share Posted June 1, 2007 bike carbs plz Quote Link to comment Share on other sites More sharing options...
kyteler Posted June 1, 2007 Share Posted June 1, 2007 Yuh, what Cam said! Quote Link to comment Share on other sites More sharing options...
lowlancer Posted June 1, 2007 Author Share Posted June 1, 2007 Nah/k Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 2, 2007 Share Posted June 2, 2007 rough finish is the norm from head shops these days. also a fuel injection doesn't atomize the fuel that well Quote Link to comment Share on other sites More sharing options...
Roman Posted June 2, 2007 Share Posted June 2, 2007 I'm not convinced about the 'rough finish' idea. (for a fuel injected system at least) My injectors basically shoot straight at the back of the valves, given the airspeed of an engine sucking 2000-7000 litres of air per minute into four tiny ports, I seriously doubt that the fuel hangs around long enough for it to condensate back into droplets. Besides the swirl/squish into the combustion chamber is doing most of the air/fuel mixing anyway. But of course if you've got carbs or throttle body injection then this might be different. BTW, port and polish IMO is only useful in certain situations.... 1. Where there's rough casting marks in the ports 2. Where the ports are actually a bottle neck, do you really know if this is the case? Beams 3SGE heads flow 300hp in standard form, the TRD 270hp engine does nothing to the ports/head. So not worth messing with! 3. Where you're wanting the volumetric efficiency of the engine to be in a different flow range. For example, a mate of my old mans is working on a pair of 1UZFE heads for a jetboat. He's basically filled up the entire ports, with weld metal, and redrilled them from higher up, so the port has a straighter shot directly at the valve. It's fucken amazing what he's done, skilled++. As he's wanting high RPM full throttle power, rather than partial throttle lowish rpm power, which is what most large displacement engines are designed around. He's also developed a program that calculates the optimal taper in the intake runners/ports, so he knows exactly how much cross sectional area he should have, at a particular distance from the valves. Randomly widening out the ports isnt going to acheive a hell of a lot. I mean look at the 4AGE engines, the most powerful 16v varient had the smallest ports out of all of them. Quote Link to comment Share on other sites More sharing options...
Hemi Posted June 2, 2007 Share Posted June 2, 2007 i love these kind of debates so much better then i pwn joo nub nub. Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 2, 2007 Share Posted June 2, 2007 yea well most injectors dont exactly make the best mist. f1 injectors are up in the trumpets for maximum atomization. When your talking about the the time the fuel air mixtue "hangs around" with fluid dynamics in that tiny bit of time the fluids still acted on the surface. But anyways the mixtures going to end up sitting behind the valve on batch fire systems anyway. Im still unsure about rough vs polished but just seems to be what the go is lately. Maybe head guys are just getting to lazy to polish them Quote Link to comment Share on other sites More sharing options...
Roman Posted June 2, 2007 Share Posted June 2, 2007 F1 cars is an irrelevant example, unless you're planning on idling at 6krpm and pulling 18,000rpm as well. You're right though, outboard injectors are better for high (7-8000+?) RPMs... Which is why some high $$/HP engines run two sets of injectors, some closer to the head for lower rpms, and some out further for high rpms. But in absolute terms, the size of the injectors, and injector duty cycle is going to have more of an effect on the misting pattern than distance from the head. Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 2, 2007 Share Posted June 2, 2007 F1 cars is an irrelevant example, unless you're planning on idling at 6krpm and pulling 18,000rpm as well. Theres heaps of other race car engines that run it and its on the top injectors well before 8000rpm. Ive seen an old v8 touring car with this set up and there limited to 7500rpm. anyway unless you've got a 4k clean up the castings polish/rough it up as you please and match the manifolds if you can be fucked Quote Link to comment Share on other sites More sharing options...
lowlancer Posted June 2, 2007 Author Share Posted June 2, 2007 Great stuff guys All I'll be doing at this stage is cleaning up the VERY rough casting marks. Soooo haggard. Anyone got pic examples of massively ported heads? Quote Link to comment Share on other sites More sharing options...
RT 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. 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. Quote Link to comment Share on other sites More sharing options...
mikuni 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.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. I agree but there are certainly advanges in getting it cleaned up. Remember that these heads, although designed and engineered well on paper, are mass produced items, cast from alloy by the thousands. This means they can benifit from a little bit of a clean, especially inside the ports. Granted, alot of the "port and pollish" work that people are carrying out themselves detracts from head, probably due to them being uninformed of the dynamics of air flow into an engine. Also, eliot did just say this.. All I'll be doing at this stage is cleaning up the VERY rough casting marks. Soooo haggard. So I don't think he's going to go over board and make them 50mm diameter ports with shiny surfaces Quote Link to comment Share on other sites More sharing options...
lowlancer Posted June 4, 2007 Author Share Posted June 4, 2007 Yuh, just clean up. I think people still have the same preconception that all heads are like the dinosaur stuff from the 50s Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted June 4, 2007 Share Posted June 4, 2007 I tidied mine up, but took some off the sharper corners to (in my head) theoretically let it flow better. I didn't open them up fuck all though, just matched to manifolds Can't really comment on what it will be like improvement wise as it will have slightly more c/r and hopefully full compression on all cylinders now 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. Quote Link to comment Share on other sites More sharing options...
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