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The Rx8, in addition to primary, secondary, and tertiary port controls, has two more actuators. One opens a flap on the intake box, I believe this is just for sound but some people claim it helps with low end torque. The other is the VDI actuator which essentially changes the length of the primary and secondary intake runners above 7,500 RPM by linking the front and rear runners closer to the ports. The positive pressure wave created from the closing of one rotor's ports supercharges the intake charge to the other rotor through this passage. It would be like having a closed plenum at low RPM and an open plenum at high Rpm. It would be cool to adapt something like that to the 12a. For all the hate that the RENI gets, the intake design is quite cool.
Diabolical1, you mention that you're a fan of bringing the outer edge of the intake port farther out, would you mind elaborating on that? What trade-offs would be in store if small changes - and what changes might they be, if any - were to be made to the 74 spec intake ports?
yeah. i like the concepts behind earlier opening. suffice it to say, at first, i was all about the closing edge, but as with most things in life, it all boils down to balance, doesn't it? so, that's where i am now with porting these engines. Jeff20B pretty much covered the trade-offs - it can start to affect idle, and the more you move in that direction the more idle will be affected, as a concept, think of it this way, the reason you get the signature sound of a bridgeport is partially from it opening so early (because you have increased the overlap).
Originally Posted by Benjamin4456
Huh, that's intriguing. I would assume that... hold on, I'm gonna do some quick math here. Lets say, just for comparison sake (in other words these are not true values), that the length of the primary runners are 10cm and the secondaries are 18cm in the manifold, and because the length of the runners in the block are essentially identical we will negate those. We're also going to state for this scenario that the air will be at STP to simplify the math and rule out other conditions. Finally it will be assumed that the reversion wave propagates at the speed of sound (yes, not necessarily true for reality, but this is conceptual so we'll go with it). Okay, so at 1000rpm we have an intake event on one rotor 1000 times per minute (oh and if any of this is wrong please call it out, I'd like to make sure that this is recorded correctly). This is the same as the eccentric shaft rotating once about every 60,000 microseconds. So now we can see that for each one degree of rotation of the eccentric shaft, it takes 117 microseconds. Since the intake events per time is equal to the number of eccentric shaft revolutions per time, each phase of induction take 167 microseconds to progress one degree (although due to the rotational path of the rotor, I don't believe this would be exact). With the same figuring, the time for one degree of rotation (not of the rotor, rather the eccentric shaft or phase of combustion) at 7000 rpm is 23.8 microseconds. The time for the reversion wave to travel in the primary intake runner is 292 microseconds and the secondary is 525 microseconds (using the values for length previously stated). In order to offset the time difference between manifold runners (233 microseconds), the intake closing of the primary would have to be delayed by about one and a half degrees to have the reversion waves arrive at the bottom of the carb at the same time at 1000rpm. However, at 7000rpm the primary closing would have to be delayed almost 10 degrees for the same effect. I can go over and check the math some other time, but for now I need to get on with things.
i read through this several times and i'm still not getting what you're trying to figure out or say. i know it was a response to Jeff20B's reversion reference, but beyond that ???
can you try again, or something else? i'm actually interested in what you're trying to say.
A way to simplify the idea about reversion pulse timing is to imagine a stock 12A with pri and sec ports the exact same size. Now think of the stock intake manifold and how its runners differ in length. This means the primary pulse will arrive under the carb earlier than the secondary pulse. We can mentally manipulate the arrival times further if we imagine bigger secondary ports (later closing timing edge).
this is interesting. never really thought of intake pulse-tuning in that context before, you know, at the port itself. i've only ever thought of it in terms of manifold and runner lengths. i guess it makes sense though because i think i read where there start at the intake valves when they tune intakes on piston engines. you live ... and learn. thanks.
I found a typo in my calculations: in post #46 where I said 167 microseconds it should be 117. There may be more, although I haven't caught any.
That's really neat how the RX-8 manifold works. I bet you could install some sort of solenoid/valve assembly where the ACV normally is. Interesting idea.
Originally Posted by diabolical1
yeah. i like the concepts behind earlier opening. suffice it to say, at first, i was all about the closing edge, but as with most things in life, it all boils down to balance, doesn't it? so, that's where i am now with porting these engines. Jeff20B pretty much covered the trade-offs - it can start to affect idle, and the more you move in that direction the more idle will be affected, as a concept, think of it this way, the reason you get the signature sound of a bridgeport is partially from it opening so early (because you have increased the overlap).
What sort of concepts are you referring to, other than those already mentioned? From what I understand, the only other major trade off for earlier opening (in addition to the rough idle) are a decrease in low end torque and shifting the powerband up. What sort of balance do you see here, maybe you could give an example from one of your setups? I wouldn't mind the brappy idle, if it didn't detract too much from other areas, but I feel like it's one of those things where it would be ideal to have either a smooth idle or a brappy idle - not some place in between with inconsistent misfires. I've also read that a 12A with no low end torque is straight up not a fun around-town power plant, which does of course make sense, I'm just once again trying to weigh the alternatives (going for a balance as you said).
Originally Posted by diabolical1
i read through this several times and i'm still not getting what you're trying to figure out or say. i know it was a response to Jeff20B's reversion reference, but beyond that ???
can you try again, or something else? i'm actually interested in what you're trying to say.
Yeah sure, I'll give it a shot. Essentially it's just what Jeff said except with some math to put it into context. The gist is that if the manifold runners were 10cm (primaries) and 18cm long (secondaries) - which is just an estimate - the primary closing edge would have to be one and a half degrees later than the secondary for their reversion pulses to arrive at the base of the carb at the same time at 1000rpm. At 7000rpm, the primary closing edge would have to be nearly 10 degrees later than the secondary for the same effect. The calculations assume standard temp and pressure (which is not accurate, hence why this is just hypothetical), that the presence of fuel doesn't alter the speed of sound in air, and a few other things. Did that clear anything up?
Yeah sure, I'll give it a shot. Essentially it's just what Jeff said except with some math to put it into context. The gist is that if the manifold runners were 10cm (primaries) and 18cm long (secondaries) - which is just an estimate - the primary closing edge would have to be one and a half degrees later than the secondary for their reversion pulses to arrive at the base of the carb at the same time at 1000rpm. At 7000rpm, the primary closing edge would have to be nearly 10 degrees later than the secondary for the same effect. The calculations assume standard temp and pressure (which is not accurate, hence why this is just hypothetical), that the presence of fuel doesn't alter the speed of sound in air, and a few other things. Did that clear anything up?
you are over thinking things. and then B, with the nikki, its much much simpler.
1. the runners are pretty close to the same length, ~185mm, the secondary runners are longer, but by maybe 50mm.
2. each runner gets its own carburetor barrel, in essence they are independent
so the reversion pulses won't match, but they don't need to
if you would like to underthink things, carb is small, and is the power limit with stock ports. making ports a little bigger helps, but making ports a lot bigger you start to loose everywhere
What sort of concepts are you referring to, other than those already mentioned? From what I understand, the only other major trade off for earlier opening (in addition to the rough idle) are a decrease in low end torque and shifting the powerband up.
i was referring to how the early-open adds power to the engine. that was the concept i was referring to. i guess the part that i didn't say, and probably why i bothered to mention it at all, is that i don't think it's as cut-and-dry as it might sound or seem. for the purposes of this thread - porting fundamentals - it's probably simpler and safer to just leave it at that.
What sort of balance do you see here, maybe you could give an example from one of your setups? I wouldn't mind the brappy idle, if it didn't detract too much from other areas, but I feel like it's one of those things where it would be ideal to have either a smooth idle or a brappy idle - not some place in between with inconsistent misfires.
when i referred to balance right there, i was specifically talking about doing intake ports. it was on the heels of saying that i used to think the closing is all important when porting an engine, but i eventually realized that the opening edge is equally important. well, striking a balance between how much earlier you open, and how much later you close is more important than doing either by itself. i used to make templates years ago, so i have thought about this stuff a lot. i still do, it's just that i don't have as much time as i did ... say ... 10 years ago.
as far as stuff i've actually built, i'll stick to the 12As. so i built one for myself that closes a little later than RB's streetport. i made no changes to the opening end. for the exhaust i went with more of a race-oriented port - probably a mistake, but that's the "2019-me" speaking. i didn't find myself slipping the clutch from a dead stop or shifting any more than i did in a stock-ported engine, but i did detect a little more urgency in it, particularly after the secondaries opened. idle was solid at 800-ish when warmed up, i did notice a little bridge-like sound whenever it was on choke, but that's about it. nothing really crazy going on with that setup. i have since driven a 12A with an RB streetport and while it behaved similar to mine, i guess i must have liked it better. i say that because i remember thinking "i'm going to do a RB streetport for my next 12A." as far as details of differences, my memory is not that good, it was just that one drive in someone else's car.
having said all that, you have to keep in mind that all of this is subjective. someone else could have driven my car, or the RB car, and given you a completely different assessment of them. also, i think i'm a little more aware, maybe savvy is a better word, than i was then (my engine was like 13-14 years ago - though i still have it) and the experience with the RB car was maybe 10-ish. so driving either car today, i might be able to notice things that i did not back then.
I've also read that a 12A with no low end torque is straight up not a fun around-town power plant, which does of course make sense, I'm just once again trying to weigh the alternatives (going for a balance as you said).
honestly, i think you found balance in Jeff20B's advice. as i said, you have OEM intake and exhaust ports that are improvements over your stock ports. it sounds like you're looking to build something nice and fun. it doesn't sound like you're chasing numbers, and that's the only reason i could see for deviating from it. drivability seems to be your main concern and i believe that combo hits the mark right on the nose.
Did that clear anything up?
yes. i guess i got lost in your math. i will have to revisit the math at some point though - maybe whenever i can realistically start thinking about building a custom manifold for something.
Well it's been four days, wow, only four days, feels like longer... Anyway, I'm back now and the engine project is in full force (new parts will be here Thursday).
Originally Posted by j9fd3s
you are over thinking things. and then B, with the nikki, its much much simpler.
if you would like to underthink things, carb is small, and is the power limit with stock ports. making ports a little bigger helps, but making ports a lot bigger you start to loose everywhere
Yes, I had been over thinking things and I am completely aware of that. I simply was curious, that's all. Sometimes it's just fun to crunch a few numbers in the name of practical application.
Also, perhaps I didn't mention it before, but the carb is getting hogged out in near future. It's already been modded rather heavily with larger venturis being one of the last things on the list. How much could a hogged nikki (say 24mm primaries, not sure about secondaries) cover in terms of a 12A running N/A; in general that is?
Originally Posted by diabolical1
when i referred to balance right there, i was specifically talking about doing intake ports. it was on the heels of saying that i used to think the closing is all important when porting an engine, but i eventually realized that the opening edge is equally important. well, striking a balance between how much earlier you open, and how much later you close is more important than doing either by itself. i used to make templates years ago, so i have thought about this stuff a lot. i still do, it's just that i don't have as much time as i did ... say ... 10 years ago.
having said all that, you have to keep in mind that all of this is subjective. someone else could have driven my car, or the RB car, and given you a completely different assessment of them. also, i think i'm a little more aware, maybe savvy is a better word, than i was then (my engine was like 13-14 years ago - though i still have it) and the experience with the RB car was maybe 10-ish. so driving either car today, i might be able to notice things that i did not back then.
honestly, i think you found balance in Jeff20B's advice. as i said, you have OEM intake and exhaust ports that are improvements over your stock ports. it sounds like you're looking to build something nice and fun. it doesn't sound like you're chasing numbers, and that's the only reason i could see for deviating from it. drivability seems to be your main concern and i believe that combo hits the mark right on the nose.
Thank you for that reply, that did help a fair bit. You are correct in that drivability is a prominent concern for me, I suppose that the idea of more power is just so tantalizing... oh well. And I think y'all are right - that I should stop and settle for something that won't have drawbacks (except for the thought that there could be more power, and there surely will be further down the road ). That said, I went ahead and reread Jeff's advice and I think that's the route I'll be taking (thanks all for sticking with this while I made a few circles around); 74 spec intake, and a bit smaller than the T2 exhaust template I now have. I'll be making the templates sometime soon here and I'll get some pictures up as soon as I do. Again for the exhaust porting, should the portion of the sleeve that narrows be brought out to the full width of the port, or left alone - I can get some pictures if what I'm talking about is unclear. Also, should anything be done about the small machining lip on the intake ports near the oil seal track? It seems like that would cause some undesirable effects, though perhaps not.
Thanks once again to everyone who has helped out in this thread so far.
Who wants to field his questions about how much HP a 74 ported 12A with a hogged out Nikki (24mm primary and let's say 29mm or 30mm secondary) could make NA. I'll try. Um, count on like 150HP maybe. Does that sound about right? Remember these are light cars so it doesn't take much to be like Charlie Sheen. WINNING!
Who wants to field his questions about how much HP a 74 ported 12A with a hogged out Nikki (24mm primary and let's say 29mm or 30mm secondary) could make NA. I'll try. Um, count on like 150HP maybe. Does that sound about right? Remember these are light cars so it doesn't take much to be like Charlie Sheen. WINNING!
Jeff, that sounds right to me. I once had my car on a dyno (with the Dell) and it put down 134HP to the wheels, if you factor in the estimated loss your are near 150HP at the crank. Its amazing you can almost double the 12A output by just doing external mods. Of course the extra bit of porting from the 74 spec can only help.
Ah but the thing about Yaw's version of a hogged out Nikki at 24mm was his bellmouth shape which he claimed was... well let's just say he preferred it. One can only guess as to why.
What we discovered later is a bellmouth is a bad idea for a venturi. Yaw's bellmouth venturis were 24mm and only flowed as much CFM as my 22mm. I didn't compare them on a flow bench but I did compare them with seat of the pants, and also jetting requirements. Yaw's 24mm carbs felt weak and small like one of my 22mm and also only needed the jets of a 22mm. I've made improvements since then of course, doing no smaller than 24.5mm at least. The power these produce and the jetting requirement are proof enough for me. Power can only go up with larger venturis. Up to a point of course. 27.5mm is the upper limit I think.
Ah but the thing about Yaw's version of a hogged out Nikki at 24mm was his bellmouth shape which he claimed was... well let's just say he preferred it. One can only guess as to why.
What we discovered later is a bellmouth is a bad idea for a venturi. Yaw's bellmouth venturis were 24mm and only flowed as much CFM as my 22mm. I didn't compare them on a flow bench but I did compare them with seat of the pants, and also jetting requirements. Yaw's 24mm carbs felt weak and small like one of my 22mm and also only needed the jets of a 22mm. I've made improvements since then of course, doing no smaller than 24.5mm at least. The power these produce and the jetting requirement are proof enough for me. Power can only go up with larger venturis. Up to a point of course. 27.5mm is the upper limit I think.
i did hesitate to post that... the Pro7 cars would do 112-116hp at the wheels, and then when you add the header they go up to about 125rwhp. this is stock engine/carb. 125rwhp is basically what Yaw did with all of his fancy stuff...
I'm glad you posted it, if just for the RWHP figures as I don't know what they could do. It would be interesting to compare one of my carbs to Yaw's and just see what they could do in a head to head vs battle or whatever lol.
The Dave ******* Racing Nikki (from Pineapple Racing) I've had for a while now and have experimented on numerous times, had some poorly cut venturis in the shape of sleeves for lack of a better word, at 25.5 and 26.0 respectively in the primaries (yes you can barely see the size difference in old photos and also in real life as I recall), and about 31 to 32ish mm secondaries. No venturi shape whatsoever, and even this monstrosity had more power than the Yaw carb did. Dave *******'s airbleeds were so big the carb did not want to run at all for me on the mains. It only had an idle circuit and an accel pump the first time I tried to drive it. That was fun. I solved it by swapping in a set of stock SA air bleeds (90 and 140) and viola! It ran! Since then I've upgraded it to the typical sizes I use in most performance carbs (70 and 80).
I've seen some pics on this forum within recent memory of perhaps another one of Dave *******'s carbs, and it too had those giant air bleeds (well just stockers but drilled out to like 150 and 200). I literally do not understand why these racing carbs had air bleeds that were so big. The jets they had in their were oversized as well which I assume was compensating for all the unwanted air in the emulsion tubes. It was using the weber air bleeds as jets which you can find on the Mazdatrix website sized every 5 numbers or .05mm which in my opinion is too wide (I prefer every .02) in the sizes of 155 and 175 but drilled out to beyond 200 if I recall right. These are not jets and do not posses a proper funnel shape. They are air bleeds and have a very straight hole. Thus they will have cornering issues like all Yaw and Sterling carbs did, because they used Holley Dominator air bleeds of a similar shape as the Mazdatrix weber bleeds for their jetting, and sized in a non-metric scale which sucked to convert while doing my research. Their carbs supposedly required the thick chunky clunky RX-3 floats and the Grose Jets (glass ball) style needles and seats just to try to corner as well as a stock Nikki can. The Racing Nikki of course had all that stuff because it certainly needed it.
Now maybe this could have ran on the big streetported pineapple racing engine I took this off of, had it not been stored with the hood off and rainwater funneled down into the engine over time from the RB spun aluminum air filter funnel shape, but what I think is that it only may have worked within a tiny RPM range, like from 5000 to 9000 (it had carbon seals). My air bleed testing bears this out about the RPM range width; smaller air bleeds allow a much wider range of operating conditions, including positive pressure territory (boost) but only up to a point, as too small can have a negative effect just like too large can, but at opposite ends of the spectrum. The trick is to get it right, but once I got it right, it has remained consistent across all carbs with the minor exception of the small air bleeds for the idle circuit. The best range for those is from 116 to 124 with the average being around 118 (or Mikuni 120 air bleeds which are about 118 to 119 metric, and can be found on eBay).
So it sounds like 125rwhp is the number to beat... But did Yaw only do 125rwhp with one of this carbs and also a free flowing exhaust? I guess I don't understand.
Hmm, I might just attempt to do that. Stockport S3 84-85 12A, matching year intake manifold and Nikki. 24.something primary venturis with I think 30mm secondaries as I believe Yaw's were 30mm. Matching N249 dizzy for the 24 degrees of mech advance, and I might play with vac advance too as the Nikki has two nipples that have timed vacuum based on throttle position available. Has anyone else tried these or just stuck with the nipple on the spacer? I don't know if I can trust that one on the spacer as most people have argued as to which one to actually use. Furthest to the left? Blah.
Question: did these stockported 12As have a stock flywheel or was like an RB light steel or aluminum allowed? Also how about exhaust? You mentioned a header. I can try a short collected RB header 2" system and also a RB long primary.
Ah Jeff, your info and ideas will never leave a thread unturned... . Off topic, but who cares, interesting stuff as always.
The nikki actually has a few timed vacuum nipples (three that I am aware of). The second from left on the spacer is what I've seen most commonly used for vac advance. The leftmost also works I believe, although I haven't checked recently. You have to be careful though, because not all t-bodies actually have the timed vacuum ports that connect to the second to left (and maybe even the leftmost) nipples - as I discovered on my '84 t-body. I have actually teed off one of the PCV lines as I found it works very well for vac advance. It's the one on the t-body that comes straight out and is to the lower right of the mixture screw. Here's a photo:
It worked perfectly for this '84 t-body that has no 'normal' timed ports.
You mentioned that the holley air bleeds are not a good replacement for the fuel jets on Nikki's due to their profile, is there a better option, or have you just stuck with drilling out the oem ones? I have yet to do my venturi's, but when I do I had planned on using the holley air bleeds, although perhaps not if there is a better option (I only have four carbs total, and I try to keep at least two complete so I'm not keen on drilling oem jets).
As for porting, I've had less time than anticipated so I still don't have all the parts cleaned up. Hopefully I can finish cleaning and get a template made tomorrow. And thanks all for the HP estimates.
Last edited by Benjamin4456; 06-20-19 at 12:41 AM.
Yes as I recall not all carbs have the same timed ports that connect to the left side of the spacer. That is another reason why I don't want to bother using it. I'll give the nipples a try in the right of the mixture screw the next time I'm around an NA Nikki.
Edit: the way these are sized is close to actual metric drill bits, but is usually off by about 2 numbers. For example, the 126 jets are actually 124 metric or 1.24mm so I order them with this in mind.
There is no list of jet sizes compared to venturi sizes as it really depends on how "good" you are at maximizing air flow CFM through the carb while taking into account the required vacuum signal that must be maintained for good drivability. Sterling tried to find the perfect size and, well, ended up at only 22mm as they had the same or similar power and CFM with vacuum signal to Yaw's 24mm bellmouth style. I cut my venturis kinda like Sterling but I took mine to the next-level of finesse and that is how I achieved much larger sizes with still ok street manners and much more power.
Question: did these stockported 12As have a stock flywheel or was like an RB light steel or aluminum allowed? Also how about exhaust? You mentioned a header. I can try a short collected RB header 2" system and also a RB long primary.
basically Pro7 was a stock 12A, stock intake, stock ignition, stock exhaust manifold, 2.5" exhaust into a muffler. stock flywheel, you could run any clutch. carb had to be stock, but you could change jets. if you bought new housings/rotors it was about 116rwhp, used parts were lower, 112 or so.
adding a header makes it Improved Touring, and added 10hp. not sure if you could do the flywheel in IT or not.
Quick post, but I've finished cleaning so I went ahead and made a 'first attempt' template. As you will see in the photo, things got a little interesting. Good lesson for me to not go so far with the burr before switching to the sanding wheels, and also to check more often against the stencil... I'll make another sometime later tonight that hopefully won't go so crazy on the inner edge. Here's the template:
Speaking of the inner edge, the lip present on the underside of the port. Is safe to bring the port that direction at all, does that lip cause any issues with airflow? It's only maybe a mm, but I don't know, seems like it could be an issue, perhaps? What is the margin there before one would be too far?
Well this second template turned out miles better than the first. Although there is one catch, it's about a mm or two taller than a 74 spec port. Now, am I going to regret going with this slightly taller port, or should I just run with it? Here's a photo if it helps:
And one comparing it to the 74 spec port:
I realise that the perspective is somewhat disorienting, so my apologies if the shape can't be made out clearly. But now then, will this taller version of the 74 spec cause noticeable losses and therefore I should make a new template (I don't believe I have any more plexi, but that could of course be remedied), or will the negative effects be negligible? My questions about removing the port lip from the previous post still stand.
Jeff, thanks for that info regarding the jets. It will definitely come in handy.
That's honestly a really good question. I suppose I made it because one, it seems like most people creating templates do it that way, and two, because it's more permanent and sturdy. It also has two dowel pin holes holes rather than one so it's more precise, or at least more consistent. And yes, I realize y'all probably don't use templates that often anymore, but I'm a first timer so I don't want to mess it up.
For some reason I hadn't thought about just tracing the paper template with a sharpie, seems like that would work fine. Again, it looked like most people used dykem or similar with a scribe (hence the need for a solid surface to run along), but they probably didn't have a paper template in the first place.
Edit: Just to run with my previous post, what effects would a taller port have - this is 'porting fundamentals' after all, so I'm still curious. And if anyone would be willing to answer the questions about the port lip along the oil seal track I'd appreciate it.
Last edited by Benjamin4456; 06-21-19 at 10:43 AM.
That looks like about 2.5mm later closing than true 74 spec. Is that right? My current 12A has that size on its primaries. It loses low end below say 2000 or so. It can still idle but a slight bit lumpy if conditions aren't totally perfect, but it is a "streetable" port job so I expected this, and I'm mostly ok with it. Though for a daily, a smoother idle might be preferred. Along with better low end torque. Adding a turbo helps from the midrange up but the really low stuff where the turbo isn't spooled, is understandably lacking. It also has a light steel flywheel which I think in retrospec a stocker would have been better, but that means less quick acceleration as it must spin up the heavier flywheel every time.
Oh, my primary opening timing is about 1mm earlier than stock.
As for my secondaries, those were copied from a pineapple ported engine and are later closing than my primaries. I think the opening was also about 1mm, same as primaries. I did use some finesse during the portiong process to make the ports appear better looking than the ports I copied from. I also did not hog out the runners. All I did was clean up the ugly sections of the casting like casting flash and stuff.
Also my intake mani is very hogged (by pineapple) which helps to reduce the unwanted reversion pulses by letting them expand a bit before they crash into the bottom of the carb. This reduces the tendency to have fuel splash up and out of the carb during quick throttle stabs. This also can hurt low RPM stuff below 2000 by making things feel a bit mushy down there. If the runners were narrow like a stock 79 manifold, it would feel more crisp but the theory is that the reversion pulses would be worse and could result is poorer drivability at low RPM but with also improved drivability at low RPM, but only around that RPM range where the reversion pulses affect things the most, or the least. Sorry if that sounds confusing.
Lol, I think that made some sense, I think... You are correct that the port is about 2mm taller than 74 spec, but by what you described, it sounds like it's a completely manageable port for the street - my secondaries would be the same size as the primaries. I don't plan changing the opening, so at least the way I understand it, I shouldn't have to worry as much about overlap and a rough idle. My exhaust ports will also be in theory smaller than yours which should also help avoid your touchy idle scenario (you mentioned before that your exhaust ports are 'true pineapple' aka huge) as well as aid in low end torque (again, that's my general understanding of it so correct me if I'm wrong).
Do you have any comments regarding the lip that follows the oil seal edge of the port. I know I've been pushing the question a lot, but it's something I'd like to better understand if anyone would be willing to give their two cents on the matter.
06-12-19, 11:26 AM
. Off topic, but who cares, interesting stuff as always.
