WINDYCITYJOHN400 Posted March 23, 2010 Report Share Posted March 23, 2010 The drag port number your searching to hear is 198-130. Your not going to find a HP curve/slide rule comparison of a stocker VS. a fully drag ported cylinder. Your going to have to face the idea, that if you fully drag port a stock cylinder....it won't be worth a crap to use for anything but drag racing. Your talking about port work that will leave you with a tiny high RPM area that you will make power in. Your gear,tire,chassis,jetting, and pipe choice will need to also match what you have done port wise. If your talking about savings.......don't worry about what you spend VS. what you give up.....think about what you'll have to spend to get a max port job to run. Those who actualy run fully done stock cyliders well, are about as rare as pro linebackers. You'll also need to be fluent in dome design concepts. (not just cc's = compression) But shape. (You gotta' really know your stuff to tune with those guys cause if your off by 1 jet size your loosing tons of power) At this point a bone stock cub is making more power than your current setup. That's why the cub is so widely used. Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted March 23, 2010 Report Share Posted March 23, 2010 Laying it on a little thick, aren't we? Let's cut the crap here. A stock banshee engine makes a certain amount of torque at a certain rpm . This rpm is determined by certain factors, the main ones being the tuned length of the exhaust pipe and the other being the port timing. Now Horsepower is torque times rpm. So if you have 50 lb of torque at say 3000 rpm, you wouldn't have bus say 25hp (numbers may be way off but the correlation is accurate". haha....yo sloryder....your pretty close with how to calculate horsepower....but your missing the dividing number. But your right...horsepower is a derived number determined by rpm and torque. But the equation is ..... TORQUE X RPM / 5252. That is torque times rpm devided by 5252. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted March 23, 2010 Author Report Share Posted March 23, 2010 haha....yo sloryder....your pretty close with how to calculate horsepower....but your missing the dividing number. But your right...horsepower is a derived number determined by rpm and torque. But the equation is ..... TORQUE X RPM / 5252. That is torque times rpm devided by 5252. Right... Basically what i was trying to get across is you can double horsepower without increasing torque Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted March 23, 2010 Report Share Posted March 23, 2010 I wouldnt use a base plate with your set-up,but if you do, set up the entire rotating assembly with top-end and run a degree wheel to scribe some marks. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted March 24, 2010 Author Report Share Posted March 24, 2010 Pics Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted March 24, 2010 Author Report Share Posted March 24, 2010 How about exhaust port shape? I've heard that it plays a role in power delivery... In my mind a port with a flat roof would cause a sharp pressure spike in the expansion chamber, and might make the powerband stronger but more peaky...Is that about right/ And also the intake port; I've noticed some builders make the top of the intake port not flat and angle upwards toward the divider...Would that produce a similar effect by smoothing out the power and maybe giving you a better rpm range? Quote Link to comment Share on other sites More sharing options...
misterww225 Posted April 6, 2010 Report Share Posted April 6, 2010 How about exhaust port shape? I've heard that it plays a role in power delivery... In my mind a port with a flat roof would cause a sharp pressure spike in the expansion chamber, and might make the powerband stronger but more peaky...Is that about right/ And also the intake port; I've noticed some builders make the top of the intake port not flat and angle upwards toward the divider...Would that produce a similar effect by smoothing out the power and maybe giving you a better rpm range? Port shape- absolutely. Your description of the results of a flat roof are right, however, as we all know a flat roof will hang a ring. I keep the roof radius to 5" and, of course, bevel the edges. When beveling the edges, remember the ring sticks out the most in the center of the port, so depending on the width of the exhaust port beyond 75%, you will need more bevel in the center to, literally, press the ring back into the piston. The angle of this bevel is fairly shallow but rounds and then blends to the port passage. Back to you question though- yes, a "flatter" roof will peak the power because the sonic wave is more defined and higher in amplitude. That it is less dispersed over time means the pulse will be at a more specific RPM range. This will turn a trail pipe into a dune pipe. The idea behind the intake shape is to improve flow. You can increase flow by decreasing the effects of eddy currents and straightening the path. Eddy currents are caused by sharp changes in the flow path. Having a smooth flow path will decrease the resistance of the flow and dramatically increase the flow rate. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted April 7, 2010 Author Report Share Posted April 7, 2010 Alot of good info in this thread Quote Link to comment Share on other sites More sharing options...
madjimmax Posted April 7, 2010 Report Share Posted April 7, 2010 By the looks of your pics if you send it out to a builder you didnt save yourself any money. If anything its gonna cost more. I'm sorry to say that but I just got my cylinders back from fast and everything is a smooth as a babys ass. By the looks of those intakes they look pretty rough Quote Link to comment Share on other sites More sharing options...
papa_smurf49319 Posted April 7, 2010 Report Share Posted April 7, 2010 By the looks of your pics if you send it out to a builder you didnt save yourself any money. If anything its gonna cost more. I'm sorry to say that but I just got my cylinders back from fast and everything is a smooth as a babys ass. By the looks of those intakes they look pretty rough You dont want your intake ports perfectly smooth! Exhaust port is ok smooth Quote Link to comment Share on other sites More sharing options...
papa_smurf49319 Posted April 7, 2010 Report Share Posted April 7, 2010 and to further claify smooth, typically you use like a 60 to 120 grit for intakes on automotive heads, and 400 grit for the exhaust. You dont want fuel puddling on the intake side because of a ultra smooth finish. Cody Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted April 8, 2010 Report Share Posted April 8, 2010 he means "rough" as in poor port symmetry, poor port shaping, etc. the intake bridge is starting to get a little narrow IMO. i would have raised before i widened to your extent. you can do alot more w/those intakes. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted April 8, 2010 Report Share Posted April 8, 2010 papasmurf is correct w/the grits. i personally use 80-120 grit on the intakes and 180 grit for the exhaust. i don't polish to a mirror look, as its a waste of time IMO. Quote Link to comment Share on other sites More sharing options...
madjimmax Posted April 9, 2010 Report Share Posted April 9, 2010 You dont want your intake ports perfectly smooth! Exhaust port is ok smooth Im not saying that it should be polished but damn thats rough, to rough in my opinion. And I guess your telling me that the set of cylinders that I just got back from FAST aint going to be worth a shit then because they for sure look a lot smoother and cut more even then that. But who am I to say I just forked out the money and had a professional do it. Where all not as good as you I guess. Thanks Mopar1 at least someone else sees what I'm seeing But I guess thats 2 of us that just dont know. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted April 9, 2010 Author Report Share Posted April 9, 2010 So let's say I get my porting to 198/ 130 and set up my intakes accordingly... Theoredically, assuming I get the right pipes for the rpm of my durations, I will be getting pretty much peak hp out of my engine; limited by transfer angles and rate of flow, right? Angles I won't even attempt to correct...But what about opening up the transfers... How much are these normally hogged out for a full drag port? What is there....10 or more hp to be gained by hogging these out AFTER getting your durations right...Or would it be worth it just to get your durations correctly matched to your pipes (cpi or shearer of course)? Quote Link to comment Share on other sites More sharing options...
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