speedy sie Posted July 15, 2012 Report Share Posted July 15, 2012 the old zx7rr head has large round inlets posts,thing of making them oval to aid inlet speed,any thoughts....they have been epoxyed up to make them smaller down to the valve,...but at the mouth they are 38mm..bit large??.. the works zx7rr's had oval inlets this is why i think i may go this way? Link to comment Share on other sites More sharing options...
ronenige Posted July 15, 2012 Report Share Posted July 15, 2012 Ray stringer is the man to speak to , I'm sure he used to insert summat into the inlets on 'em Link to comment Share on other sites More sharing options...
speedy sie Posted July 15, 2012 Author Report Share Posted July 15, 2012 yep ill give him call tomorow Link to comment Share on other sites More sharing options...
Benji Posted July 15, 2012 Report Share Posted July 15, 2012 I think they used to only use the inserts on the exhaust ports to get rid of the step from the head to the header pipes. Link to comment Share on other sites More sharing options...
speedy sie Posted July 15, 2012 Author Report Share Posted July 15, 2012 seen these and seen the exhaust port welded up,might go this way aswell Link to comment Share on other sites More sharing options...
theo Posted July 15, 2012 Report Share Posted July 15, 2012 As usual, its not as simple as ovals being better cos they are works parts. They'll only work as intended if they are coupled with revised porting (might include the inlet valve guide and the shape of the back of the valve) and whatever else the works head had. But, i going to go out on a limb, and think youll just go oval cos you like the sound of 'works'. Link to comment Share on other sites More sharing options...
speedy sie Posted July 15, 2012 Author Report Share Posted July 15, 2012 no..not jus because the works head has it.. iv seen a few ported heads and they went oval,i know it all about air trubulance and air friction,and the xro engine has oval port ,as does the road srad,iv been reading about the pro and cons of it,and i think the head will benefit from it,at the moment it has 38mm round inlets witch i think is a bit to large. Link to comment Share on other sites More sharing options...
theo Posted July 15, 2012 Report Share Posted July 15, 2012 Specifically, Why do you think the ovals will work better? Link to comment Share on other sites More sharing options...
spannerman Posted July 15, 2012 Report Share Posted July 15, 2012 sie pm me your address and ill send you an old 4 stroke tuning book i have. it has all that stuff in plus more yes i know you may struggle reading it but your lass can read it to you at bedtime Link to comment Share on other sites More sharing options...
theo Posted July 15, 2012 Report Share Posted July 15, 2012 I dont actually think there is a hard and fast rule such as 'oval ports are better'. Yes bifurcated ports (i.e. a single port splitting into two to feed two inlet valves) most often have an oval shape as this tapers up towards the throttle body, but the throttle body itself will always be round on the bikes you are talking about. So youre going from an oval - circle - oval - bifurcated ports. Also to be noted, the oval throttle bodies run in Lemans cars by chevrolet are a very different shape to the oval throttle bodies youll see in a ducati 1098 for example. Link to comment Share on other sites More sharing options...
speedy sie Posted July 16, 2012 Author Report Share Posted July 16, 2012 sie pm me your address and ill send you an old 4 stroke tuning book i have. it has all that stuff in plus more yes i know you may struggle reading it but your lass can read it to you at bedtime oh you star...and have the old lady read it to me in bed....thats one fine idea Link to comment Share on other sites More sharing options...
speedy sie Posted July 16, 2012 Author Report Share Posted July 16, 2012 my thought is the valves them selves are in an oval shape set up,and MOST modern bikes run round to oval injection rubbers as did most of the carbed bikes,so plan was to copy. as for tunning the engine,the posts in a zx7r head are hard to open up(if you wanted to do this) as they are cast in a way that they have thin side wall's on the inlets,as they are cast in a way that has the flange are thicker than further down towards the head it self,and to get the inlet straighter you have to open them up to oval as this is wot the post is like further down the inlet,i just think round inlets are best but in some instance like a single valve head,but then two valves are used then oval is a better set up?? Link to comment Share on other sites More sharing options...
theo Posted July 16, 2012 Report Share Posted July 16, 2012 Are the throttle bodies circular or oval? In the 1098 for example, which is injected of course, the actual throttle bodies are oval. Link to comment Share on other sites More sharing options...
speedy sie Posted July 16, 2012 Author Report Share Posted July 16, 2012 no the fcr's are round as they are race flat slide carbs Link to comment Share on other sites More sharing options...
Gregorious77 Posted July 16, 2012 Report Share Posted July 16, 2012 no the fcr's are round as they are race flat slide carbs Ah well then you need Hexagonal intakes due to the vacuum fluctuations 4Um above the valve seat event horizon caused by the flat slides electromagnetic pulse generation at 4409 RPM, if they were curved slides you would want pentagonal intakes to invert the pressure waves at the peak of valve lift. Link to comment Share on other sites More sharing options...
kaighn80 Posted July 16, 2012 Report Share Posted July 16, 2012 ok then smooth vs rough, whats the opinions there, i tend towards rough purely because of something i learned in gcse science, being that turbulant air moves faster and probably helps to stop fuel drop out (discussion about golfballs and dimples) Link to comment Share on other sites More sharing options...
theo Posted July 16, 2012 Report Share Posted July 16, 2012 Golf balls and dimples (Something I asked the head of engine development at uni): Golf balls fly further with dimples. This is certainly true. However, you must think of a gold ball flying through the air, creating a wake behind it. If you can reduce the size of this wake (which funnily enough the dimples do by ensuring that the flow remains attached to golf ball for longer) then you have reduced the drag on the golf ball. The ball now flies further However, the effect of the wake (its size and therefore the magnitude of the drag force) is the over-riding factor for a golf ball which has a low surface area (a sphere has the lowest possible surface area:volume ratio). The surface friction for a gold ball is therefore negligible and its more important to reduce the size of the wake, rather than reduce the surface friction. This is not the case with ports, where the surface area is the over-riding parasitic force. Whilst there is a lot of debate over rough (and by this i mean very very small imperfections designed to induce turbulent flow) and smooth surfaces for ports, dimples like on a golf ball will only worsen the situation. Link to comment Share on other sites More sharing options...
speedy sie Posted July 17, 2012 Author Report Share Posted July 17, 2012 at a tangent to inlet air mix,had a though many years ago ,about a impeller blade inside the inlet to swirl the air mix round?? Link to comment Share on other sites More sharing options...
Gregorious77 Posted July 17, 2012 Report Share Posted July 17, 2012 line them with mole skin?!? Link to comment Share on other sites More sharing options...
Romski Posted July 17, 2012 Report Share Posted July 17, 2012 Be different, triangle ports. Link to comment Share on other sites More sharing options...
theo Posted July 17, 2012 Report Share Posted July 17, 2012 at a tangent to inlet air mix,had a though many years ago ,about a impeller blade inside the inlet to swirl the air mix round?? Great idea, but youve just invented the supercharger. Anything other than a supercharger which compresses the air, increases its density and meaning you can get more of it, along with more fuel into the engine, will just be a restriction, and remove energy from the incoming charge. Doesnt matter if it 'mixes it up a bit', it'll be worse than having nothing there. Link to comment Share on other sites More sharing options...
Benji Posted July 17, 2012 Report Share Posted July 17, 2012 at a tangent to inlet air mix,had a though many years ago ,about a impeller blade inside the inlet to swirl the air mix round?? Just leave the outside rough, avoid wall wetting, with the speed of the air you will naturally get turbulence from the rough surface of the inlet tract. As for putting an impeller in there sounds a max power buy 200bhp for a tenner idea, but in reality it will be worse. Link to comment Share on other sites More sharing options...
lorenzo Posted July 17, 2012 Report Share Posted July 17, 2012 Anything other than a supercharger which compresses the air, increases its density and meaning you can get more of it, along with more fuel into the engine, will just be a restriction, and remove energy from the incoming charge. Doesnt matter if it 'mixes it up a bit', it'll be worse than having nothing there. How about a secondary air source to add turbulence? On the face of it you could describe it as an inlet leak, but a metered air source, a tiny one perhaps, near the engine on the inlet tract, would create turbulence. Or am i talking shit? Link to comment Share on other sites More sharing options...
theo Posted July 17, 2012 Report Share Posted July 17, 2012 My feeling is that if it was a benefit, someone would have done it before. However, there is a guy called Apfelbeck, who made very powerful cylinder heads that had 2 ports feeding one valve. One came almost vertically down whilst the other was more conventionally situated. That did work, though I suspect more from increased flow rather than inducing turbulence instead. Link to comment Share on other sites More sharing options...
kaighn80 Posted July 18, 2012 Report Share Posted July 18, 2012 what about rifling the bores then would that work? Link to comment Share on other sites More sharing options...
lorenzo Posted July 19, 2012 Report Share Posted July 19, 2012 what about rifling the bores then would that work? It would make your inlet charge more accurate over distance... Link to comment Share on other sites More sharing options...
gregtrx Posted July 22, 2012 Report Share Posted July 22, 2012 You want to run a cryo cooled airbox and fuel tank to cram more charge in. Link to comment Share on other sites More sharing options...
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