rotarenvy

All that paper talks about is how low boost systems run at higher bost cause excessive back pressure. They are talking about 3:1 back pressure and how it causes problems.

TeamRX8

iTrader: (25)

yes, at the beginning, but later after they figured out what what was going on they were able to implement changes and improvements that resolved those issues. It's not that hard to understand and I'm not sure why you're questioning it, except maybe you weren't following Brettus discussion in his thread about PR?

It's also why I stated previously that I have no intention to use small manifold runners to force high velocity into the turbo. Using the smaller, more responsive turbo offsets having to do that and instead use lower velocity/less restrictive manifold piping to help relieve the PR inside the engine to instead move it into the WG/turbine area. Small runners limit it from flowing freely into the WG and instead trap it in the engine. I intend to use 2" pipe, whereas most people use 1.5" pipe, for the primary runners. On a low mount manifold the primary pipes aren't really that long to begin with so while percentage wise it looks like a big amount of volume increase in the overall sense it isn't, but just like my results on the Renesis header thread it does make a big difference on it being able to help minimize combustion gases from being trapped in the rotor chamber as it transitions from the exhaust to intake phase.

It makes sense if you really think it through; at 3 PR there's 3x more combustion gas trying to escape out the side exhaust port, which is not really designed for that scenario and is a poor design even for NA use, in the very short time the exhaust port window is open as the rotor side orbits across and over it. Inhibiting that with a too small of an exhaust pipe is going to cause problems. Regardless, even if it does slow response some I'm prepared to live with that to improve engine longevity. Which again while the Pettit mods improve the situation, the reality is that the higher the the PR on any engine always results in shorter engine life. While it takes a toll on any engine, it's more of one on a Renesis due to the side exhaust port and side-seal arrangement.

We're not playing games here ... like I said earlier, it's not just an engine only parameter, there's a reason that was happening ... I've been at this a long time having bought my RX8 in April 2005. What I'm laying out here is almost 13 years of personal experience and I've devoted a lot of time into understanding the Renesis and learning anything I could from any source possible. Some of my ideas will likely not pan out, which is always the case, but in general I think this engine is going to perform a lot better than many people believe. Just like my Renesis header design got poo-poo'd by most members here for about that long too. Well it's not a theory once it's proven out.

Again, 3 PR on a race engine operating most of the time out at the choke limit is going to be a big issue. On this street engine it will be operating in the more efficient part of the map with only the occasional rev out maybe. The goal here is low-end performance, but some sacrifices have to be made to make for a reasonable engine life regardless.

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Brettus

iTrader: (2)

I'm really shocked that you think that will make a significant difference to what is happening inside the engine. Backpressure is determined mostly by your turbo size. The amount you reduce it by at the engine by fitting big pipes will be inconsequential.......IMO Have you done any calcs on this ?

TeamRX8

iTrader: (25)

I'm going to suggest that you re-read this and try to comprehend what I posted. I'm also going to suggest that you try to think it through some more and perhaps lay off with the hair-trigger responses. I wasn't going to respond to you as per my earlier post and mistakenly did so to try and convey that using the wrong method and then deleted my mistake. I apologize for this. As long as your posts are sincere and on topic I'll try to be more understanding going forward.

If you still feel the same way about that post tomorrow I'll respond accordingly


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Brettus

iTrader: (2)

Well ... I am being sincere . I'd like to know if you have calculated the difference in pressure drop between say .... 3x1.5" pipes and 3x2" pipes ?

If you have ... that would be of interest to me . And sorry for jumping to a conclusion instead of asking the above.

TeamRX8

iTrader: (25)

I took the time to explain why and it seems as if you didn't grasp or read it. I don't like repeating myself when it's right in front of your eyes; 2nd & 3rd paragraphs, sorry for being that way.

but trying to be more understanding, I was doing multiple edits and perhaps you were reading before I was done. Going back and re-reading your question; it seems to me that you're making an assumption and I'm advocating that the assumption I think you've made is incorrect.

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Brettus

iTrader: (2)

I read your explanation and understand that it's a step in the right direction. My question is , how much of a step ? If it's just a matter of say ..... 1psi improvement, is that really worth all the pain you will go through to fit 2" pipes in that cramped space ? You will have to be somewhat of a magician to even pull it off !

TeamRX8

iTrader: (25)

I'm fairly confident it's the reason your turbo isn't responding the way it should and all the other issues. This is what I didn't explain to you previously. You have to understand that small runners do increase velocity to help response at low rpm. The flip side is that at high rpm the amount of time to transfer these gasses from the chamber to the turbo becomes shorter and shorter. So as RPM climbs the smaller primaries begin to restrict the flow so much IMO that PR in the chamber is higher than PR at the turbo. The larger primaries relieve this, which is going to not only help clear out the chamber, but also drive the turbo harder for better performance. You got the double whammy going on there;choking off the turbo and carrying over excessive PR/combustion gasses into the intake cycle.

Sorry, and choking it off from your wastegate too unless you have extra side ports feeding it directly.


Also,in the header thread I posted I'm telling you that a 1.75" 16 Ga. OD Tube ID is too small for NA, so anything smaller than that IMO is certainly too small for a turbo Renesis. 2" will provide full circumference coverage for the the main exhaust port openings which I don't thing going any larger than this will provide much if any benefit. I also don't think it's any benefit to form the pipe/tube to match the rectangular opening. You might need to oval it a bit to cover the full rectangular port opening but otherwise let it just overlap out onto the flange and weld it up that way. Which greatly simplifies building the manifold as the formed rectangular to round transition is the hardest part of the job, other than maybe trying to fit & pipe the largest possible turbo down there. Having a big honking T4 flange isn't doing you any favors either. That's why I'm going V-band and then IWG on the 7163 is another big piping advantage too as long as the proper canister is used to control it properly. Which for my concept is the Turbosmart unit.

In theory you could use a smaller pipe for the smaller siamese center port opening, but I'm not sure it's worth the bother. I keep repeating myself here; the Renesis can't be treated the same as any other engine. You need to really put the thinking cap on and consider things for this engine that nobody would ever consider for a standard engine.

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Brettus

iTrader: (2)

I do understand that there is a trade off between response and backpressure . You will recall that this was discussed at some length before I had my manifold built. I settled on 11/2" more because that was what would fit plus research I did suggested the penalty wouldn't be that great for the power levels I wanted to run .So far ,my results are better than what others have seen with bigger manifolds so I don't see it as a major issue , at my current power level anyway.
In your case however, wanting to run at a lower power level, the penalty is even less. And my point about getting 2" to fit is a valid one.

RIWWP

iTrader: (2)

Being careful to avoid talking out of my ***...

I think your openness to it falling on it's face ... and exploring unique ways to handle the reasons why it would ... is precisely why the idea has a lot more going for it than people may expect at first glance. You are using an approach which values precision work with the parts most people ignore, rather than a brute force approach for the points that everyone focuses on.

Regarding the loss of the UIM, I would expect some sort of change, but with the understanding that I am not nearly enough of an expert, I suspect that you will see a net benefit vs piping through the stock UIM. The compressor and IC change the flow dynamics enough that the UIM's engineering features probably won't be nearly as applicable anyway, the excess valving to optimize NA power gets replaced by the compressor's whole function, and the shorter lower volume route removes complexity, straights the flow route, and reduces the volume of air to compress.

I think it's a great idea.

TeamRX8

iTrader: (25)

Thanks.

Brettus, I understand your position and am not trying to discount your belief in any way, but I respectfully disagree with you on multiple points. There’s no point in is trying to convince the other any further and instead just accept it for what it is. However, just because you think it’s better the way you’re doing it now doesn’t necessarily mean you found the optimum method doing it the other way before, or now for that matter.

Again, imo you’ve limited yourself in multiple ways by certain choices, which you seem to agree with me on that point. I suppose we’ll just have to wait and see if I ever execute this using my choices and then compare results. Despite our target goals being different I still think there will be some good comparison points for us to consider. Otherwise I think you can lay off questioning/challenging everything just because you believe that your way is better.

We’ve already established that neither of us is going to switch positions until there are results for both to assess and judge from there. I already accepted this, which is why I signed off from your thread. I’m not mad or upset with you. I just came to respect that your going to do it your way regardless and my suggestions were only aggravating you to think I had negative ulterior motives. I hope you’ll do the same for me.



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AAaF

Yes I used the table shown in the picture you mention. I guess the values will change a bit, but remember that when increasing pressure, you are changing density of air, far more than the volume. I assume that volume is close to identical, but density is close to doubled(molecules packed twice as tight)

Understood, if you port it, you'll often shift Ve curve upwards, getting the peak Ve at higher RPM. But looking at the compressor map, this does not look beneficial, the 13B-SI as it is, looks to be close to perfect match. If you port, and get higher Ve at higher RPM, you'll need to move more air, and moving out of the efficiency range, similar to the 4- port renesis.

Just a refresh for new readers:

TeamRX8

iTrader: (25)

Well I already decided not to port. In my minds eye that will only result in the EFR 7163 operating faster and further towards the inefficient choke line area. It’d be much better to run higher boost, which E85 fuel with all the other correct parameters such as timing, fuel ratio, etc. would allow for. This will help the turbo to instead operate in the more efficient compressor map area, which also favors running higher boost. Kind of a win-win the way I see it. So 25 psig or so boost might be a possibility if the turbo manifold/WG allows for the engine to clear the rotor chamber enough running that high of a PR.

But Ve for FI changes a lot more “than a bit” over NA Ve, even with resonance assisting NA Ve on the Renesis. Seems like you might want to investigate that some more.

EDIT: For FI you have to look MAP (manifold absolute pressure) to determine the Ve on an FI engine. I posted a weblink in a reply to to your reply on this reply (ugh, that sounds confusing) and equation 7 in that weblink demonstrates this.



In the header thread I did, I stated that the Renesis NA is equivalent to a lightly supercharged engine due to the intake resonance design and all the pulse tuning for it comes from the intake system only due to it having no exhaust overlap because you can’t have resonance tuning on the exhaust side without overlap between the intake and exhaust cycle. It just can’t exist without it, period. This is what makes the Renesis unique among all engines; that all the performance comes entirely from the intake tuning (which is pretty amazing considering a Pro built 1.3L 2-rotor unported 6-port will typically pull 265 - 270 peak fwhp) and no port timing overlap changes so many factors that you can’t just blindly apply common techniques from other engines because they either won’t work or have negative impact rather than positive.



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AAaF

Thanks, good point, without resonance, its impossible to get above 100% Ve, haven't thought about that. But if you exclude the effects resonances have(who also occurs at Ve below 100%, yes), then I do not see why Ve should change massively...?

But I'm also quite sure that even at FI, resonances will occur somewhere, but even estimating this is above my league. Among other things, if density of air is increased, resonance frequency for a given length will lower. Air temp is another thing that affect a lot. As said, above me....

EDIT: Not sure what if resonance fill increase or lower, but it will change a lot with pressure, density and temperature.

AAaF

Remember that you intended to use as much as possible of the pressure pulses, if you are to transfer the pulse energy from port to turbine as efficient as possible, it is better to match areas. If you go from one volume to another, you will loose pulse energy, especially if transition between areas are sudden(but that is a bit intuitive). Just a input from another industry

TeamRX8

iTrader: (25)

So in doing some research I came across a formula discussed on the Rotary Car Club forum by RX7Club member and vendor; Rice Racing, who can be a bit controversial, but imo the guy is smart and knows his stuff about rotary engine performance, that can be used to determine the boost figure required to determine what it takes to reach a certain peak bhp (flywheel hp) based off the known peak bhp of the NA engine. He used the formula with known rotary engine bhp output from various race shop vendors using a variety of known turbo 12B and 13B with known dyno results, known modifications like OE-port, s-port, b-port, p-port etc., and boost pressures and the calculated NA results were pretty spot on for what those same engines could be expected to do NA.

In discussing this concept with some very experienced Renesis people I know, a pro builder told me he built and ran an unported 4-port auto engine a number of years back and it dyno’d around 210 peak bhp @ 6800 rpm. His 6-port NA engines usually output upper 26x - low 27x bhp as a comparison. These numbers seem valid to me and I’m going to use 210 bhp as the 4-port NA bhp output for these calculations. If I were to build this engine it will be pro built with all the right parts as previously discussed earlier in the thread.

So the formula is based on the concept of whatever the engine does NA, which we can reasonably assume is 1 Bar atmospheric pressure, that for every increase in x Bar of boost, when converted to absolute pressure, will increase bhp power output by that same amount. So if the engine is making 100 bhp at 1 bar absolute pressure if we boost it by 1bar, which will be 2 Bar absolute, the new putput will be 2 x 100 bhp = 200 bhp.

So I decided to use this formula to determine what boost level is required to achieve my estimated 350 rwhp output for what this concept might produce. Just to be fair I’ll point out that there are a few experienced Renesis turbo people on this forum who think the 4-port engine with the BW EFR 7163F(v) turbo will never be able to achieve a 350 rwhp output. However, I respectfully disagree with that assessment. Obviously we’ll never know 100% until I or someone else actually pulls the trigger to build and test one. I am going to base the calculations on the output value though.

EDIT: The 210 bhp value used on these calcs is artificially high due to the engine having the S-DAIS resonating intake system on it. The value needs to be based on the engine without S-DAIS on it to be a more accurate model of what actual performance the turbo adds to it vs. what actual performance it had without S-DAIS. I’m going to leave it up because I think the calculations gave some value, but this demonstrates how you need accurate values to start with to achieve accurate estimating results

So moving to the formula it goes like this:

NA(y + 1) = Turbo bhp

Where NA = known NA bhp output and y = (x/14.7) and x = required boost psig pressure. If we use x = 0 psig boost we get the NA bhp output figure so the formula does seem to work in that sense.

I already established that 210 bhp is a known output for a pro built unported 4-port NA engine

If we rework the formula we get:

200(x/14.7+ 1) = Turbo bhp which translates to:

200x/14.7 + 210 = Turbo bhp

200x/14.7 = Turbo bhp - 210

200x = 14.7(Turbo bhp - 210)

X = Required Boost PSIG = [14.7(Turbo bhp - 210]/200

However our target is 350 rwhp and we need to figure out how much drivetrain hp loss there is from the flywheel to the rear tire contact patch in order to get from bhp to rwhp. I know that a pro built 6-port engine with a 265 - 270 bhp output will produce rwhp output with OE drivetrain (OE flywheel, clutch, trans, driveshaft, rear diff, tire/wheel weight 40 lbs each and race exhaust system including high flow cat converter) around 225 rwhp conservativly. I still have my HJS Motorsport racing cat with 100 cpis core and rated at 400 hp from my race RX8 that I would use on this concept if I were to build it. But I figure that the higher hp will have more drivetrain drag plus I want to be conservative, so I’m going to choose 80 hp loss at the wheels to use in the calculation. Which now looks like this:

Required Turbo bhp = 350 rwhp estimate + 80 hp drivetrain loss estimate

Required Turbo bhp = 430 bhp

Required Boost PSIG = [14.7(Turbo bhp - 210]/200

Required Boost PSIG = [14.7(430 - 210]/200

Required Boost PSIG = [14.7(220)]/200 = 3234/200 = 16.1 psig

So to achieve the estimated peak 350 rwhp based on this formula the turbo needs to be at roughly 16.2 psig around 6800 rpm or so with a 7000 rpm red-line. The higher boost pressure I mentioned would be used at lower rpm ranges to maximize low-end torque which I’m hoping could peak by no later than 3500 rpm but am hopeful of lower around 3000 rpm and then taper off to the estimated 16.2 psig level near the 7000 rpm redline. That’s how I see it anyway as a general initial estimate. It may prove to be higher I think because the formula is rather simplified and may not account for a few extraneous factors.



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TeamRX8

iTrader: (25)

Somewhat agree, but there are other factors involved that I detailed out in previous posts (sometimes it seems as if you either didn’t read or comprehend them fully), which is why the 2” Sch. 40/Standard pipe I’ve chosen for the turbo manifold is the best fit to the main rectangular exhaust port opening circumference and it’s very strong for withstanding heat expansion cracking as well as carrying the turbo weight & vibration load which is why I chose it. The ID is 2.067” which is actually just a fraction larger on circumference than the port. However the next size down is 1.5”, which for Sch. 40/Standard thickness and is what many Renesis turbo builders are using, is much smaller circumference than the main end exhaust ports with only a 1.610” ID. Even the Sch. 10/Thinwall thickness is closer, but still too small at 1.682” ID. Either of those would work for the smaller siamese center port though.

So based on what you said then the best fit would be 2” Sch. 40 pipe and elbows for the two main end ports and 1.5” Sch 40 or Sch. 10 for the smaller center siamese port. These are not only the best fit for the exhaust port openings, if you read my earlier post they’re also the best fit for the rotor chamber to have the least amount of flow resistance for clearing out combustion chamber gases to have equal PR between the rotor chamber with the turbo and wastegate positions. The 1.5” pipe size other turbo Renesis kits are using for the exhaust manifold does help increase velocity for lower flow/rpm levels, but there is no free lunch because at higher rpms my position is that it’s too small and the restriction ends up resulting in the rotor chamber having a higher PR when the exhaust port closes than the resulting PR at the turbo and wastegate due to the excessive restriction of the too small exhaust manifold pipe size.

The other factor you’re not taking into account is they are using larger and heavier turbine wheels, which then need high velocity to help get spinning. The EFR turbine of equivalent size to a Garrett turbine is roughly 50% lighter. This is one of the primary reasons they spin up and reach full boost pressure quicker than an equivalently sized Garrett turbo. However in this case, if we were to use Brettus current turbo for a comparison, the EFR 7163 turbine is smaller, which means the percentage that it’s lighter than his larger Garrett-based turbine is even greater. When you’re trying to spin up to 120,000 rpm turbine speed that weight difference then makes a huge difference in how quickly it can do that. And it’s not just a lot lighter. It also only has a 0.85 AR as compared to his 1.03 AR, which is where it will actually will receive higher velocity exhaust gasses too as a result.

So my contention is that this is going to both offset the the lower velocity through the manifold piping, but also not going to be restrictive about transfering PR equally between the rotor chamber and the turbo/wastegate positions for letting the exhaust gasses flow freely clearing as much combustion gasses/PR out of the rotor chamber and then also not carrying as much of it over into the intake cycle. The EFR 7163 V-band IWG turbo being proposed for this proposal has both the highest potential turbine flow of all the 7163 turbine flange options and the internal wastegate is large enough to handle the excess flow that needs to bypass the turbine without choking combustion gasses/PR from exiting the rotor chamber combined with manifold piping optimized not to do that either. This concept is also limited to a 7000 rpm red-line, which is why the chosen, what I’ll now call the “little big turbo” can spin up quickly yet have enough total flow coverage for making strong power to that limit and also being capable of expelling excess flow through the wastegate to that limit. I seriously think many people are underestimating the potential of this turbo for the chosen application duty.

Anything that’s not cleared out of the rotor chamber before the exhaust port closes carries over as EGR into the intake cycle. EDIT: I had incorrectly undrstood what Brettus did wrt controlling EGR flow in his patent thread per his later reply below so I deleted that incorrect assessment from here.

So again, imo there’s a lot more to it than just the pulse deal you stated. The EFR 7163 turbine isn’t as dependent on that factor as you proposed because you clearly haven’t factored in the differences of this particular application as it compares to other applications using different concepts and factors that weigh into the overall equation.

TeamRX8

iTrader: (25)

Well look guys. I can’t keep getting into these long winded replies to repeat my self over and over again or correcting your misunderstandings etc. At some point I’m just going to not answer or just move on to keep this thread going on topic. You have to figure out how to keep up on your own. I want to keep this on topic and not be chasing down every misunderstanding. If you think I made an error or stated something wrong I’ll be open minded and consider it, but if I disagree probably either will just say I disagree or won’t respond if I strongly disagree, as in you’re way off base.





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strokercharged95gt

I built my manifold out of 2" Sch 40 mild steel and it has been a beast, no cracks or warps. Was just as strong as the day I welded it up. 0.165" wall thickness FTW! Pipe was so thick, I had to set the welds in using flux-cored wire (MIG wouldn't penetrate deep enough on my 140 amp welder). Weighs like 16 lbs though. Therefore, I say go with the 2" primaries.

TeamRX8

iTrader: (25)

I might consider 16 Ga T321 stainless 2” OD tube instead just for that reason, but the cost goes up quite a bit. The strength is actually greater despite the thinner material because of the T321 high heat properties. The ID would be 1.874” though (0.063” thickness) which is just a hair smaller than the exhaust port though, but close enough to be comfortable with. 18 Ga would be perfect though with a 1.920” ID, but I’m not sure if it can handle the stress even with that material since it’s only 0.040” thick. It works fine for an NA header as does 20 Ga. at 0.032” thickness.

I’d never use steel though for a number of reasons, mostly because I’m in the stainless steel fab business. You’re supposed to bevel Sch 40 pipe joints to a 1/8” flat landing, run a penetrating pass there first, then fill in with stringer beads to finish out the bevel area. That’s why you probably couldn’t penetrate. Because otherwise a 140A welder should be able to do it the bevel way easily.

EDIT: Meh, 2” Sch 40 T304 fittings are so cheap I don’t care if it weighs more for a street car with power. I’m going to stick with that plan instead. Though I may use 1.5” for the smaller siamese port now. With the piping layout I’m looking at now a 1.5” pipe size for the center port would be sufficient for flow and work in nicely with rest of the piping since the smaller elbows allow for a tighter radius for easier fitment.

The Pac Performance 500 4-port turbo manifold blocked off the center siamese port and only used the two main end exhaust ports. That was a mistake that they didn’t ever recognize imo. My goal is to try and make the turbo manifold piping as short as possible. I need to get out to where my car is to check a few things since it currently is sitting there on stands without the front exhaust section installed.

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Brettus

iTrader: (2)

I did my best to explain it but you obviously missed this point:
A crucial part of the whole design is that I CAN block EGR under load or at any other time it is beneficial. Go back and have a look at the valve design and you will see this.



BTW: you do realise that your carryover EGR will be over 30% more than what mine is (at the same power) don't you ?

TeamRX8

iTrader: (25)

Ok, sorry about that. I was having some difficulty following it as we discussed there. So I can see having missed that you had that covered. So good job thinking it through! And my apology for not giving you more credit than that too. I should have known better too.

TeamRX8

iTrader: (25)

Re: carry over EGR. Well we’ll have to see. I said earlier that there were some details that I wouldn’t be detailing out fully in this thread, though I have expressed a few ideas that I think are going to assist with that too. Again, we’re both tackling it from a different approach and until there are results from both to compare against we won’t really have anything substantial to claim either way. Mine is still just a concept for now, though I feel fairly confident in it despite you seeing it differently.


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AAaF

No worries, not insulted, I do not know what left wing means, I guess sometimes ignorance is a blessing

I think its me mixing up the expressions and definitions, as previously mentioned I'm trying to learn. But think we kind of have the same basic understanding. I thought about Ve as how much filling you have in each stroke. With 100% you'll have atmosphere inside cylinder when NA, or whatever the compressor delivers if you are FI. Imagine a very slow engine where this is the case, no resonances. Now the volume will be the same, but density of molecules doubled if you have doubled the atmospheric pressure. Now you can do a calculation of Ve x Pressure to find the fuel you should spray. Therefore I came from the opposite side from what was explained in the link you provided(thanks!), I thought that you multiplied Ve with whatever pressure you are using, to get the amount of air going in, I did not know that it was baked together in one lump, and expressed as Ve FI, if you understand what I mean?

Thing is that when I did it this way(Ve x Pr), then the numbers looked sensible for the results I've seen. If you multiply NA hp with FI absolute pressure, you end up reasonably correct. For example Brettus who had 410whp@16PSI. According to this simplified approach:
231fwhp x (16+14,7)/14,7) = 231 x 2,09 = 482fwhp
Or old draggers SC(330whp:
231 x (13+14,7)= 435fwhp. Here we need to subtract 40-50hp drive power to the SC.

I hope you realize this project, I think it can evolve our understanding of Renesis and FI.

TeamRX8

iTrader: (25)

So after considering this more there is a point in here that I now recognize that I missed previously. I did my theoretical boost calculations based on a Renesis using the S-DAIS resonating intake, which is incorrect. Since those harmonics are out the window with FI, especially if I do the plenum on the LIM which deletes the UIM, then the NA bhp value for the calculation needs to be based on the engine without S-DAIS on it. So the 210 bhp number the pro builder saw on the engine dyno is artificially high due to it having the S-DAIS resonance design on it.

As demonstrated in the Mazda graph above, the engine performance is lower without S-DAIS and I’d either need to estimate that that loss is based on the Mazda graph or have the turbo system plenum/TB assembly ready when the engine goes on the dyno for break-in, and power runs once broken in, to determine a more accurate NA bhp value for the calcs to estimating the required boost pressure to achieve a 350 rwhp peak output. Probably closer to 20 psig I’m thinking now, though the 80 bhp drivetrain loss is likely too conservative too (high). Guess it was me out in left field afterall ...

And I also came to the same conclusion you did, and completely glossed over your point previously, that porting was going to do more harm than good for keeping the turbo operating in the more efficient area of the compressor flow map. So my apology for not fully grasping your well thought out points.





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