When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Nice to report some progress! Diffusor is painted and mounted. They did an awesome job with the piece I provided and is now super secure. They did have to clean up a ton of work from the hack who plasma'd the s**t out of my inner trunk area but looks great now and totally worth the investment to fix / clean it up.
Custom muffler and full vband is just about complete as well. Seriously looks awesome and def saved more than a few lbs. The Laguna tip I requested is def a fun piece, ha.
So all that's left for this phase is chassis mounting my Esprit 1640mm dry GT, installing custom quick release center flat-bottom section (from engine / trans area back to differential where it meets the rear diffusor, front is completely sealed with KnightSports under tray and Laile engine cover) and custom carbon fender extensions ala RE / Ridox style. Then off to Laguna for some beta testing.
Although I'm not sure how balanced front end downforce will be with so much rear aero… we'll see!
functionally it’s poorly executed on multiple levels
.
You need to be more specific when making statements like that. I'm not a mind reader.
Regarding work and design, the pro D1 shop who's completing all the fab work seems to think the diffuser was road course worthy and their work sound, I'm curious where you see fault. Could you please elaborate (this is where the being specific part comes in)?
On a side note, you could always take a higher road to be kind / helpful as opposed to making negative, condescending, snide, rude, etc remarks. I've always made it clear that I value your input but you seem to be preoccupied with being the resident know-it-all. There is no competition other than what you perceive in your mind. High time to leave the nonsense behind.
"We shall pass this way on Earth but once, if there is any kindness we can show or good act we can do, let us do it now, for we will never pass this way again." -Stephen Grellet
ps- unless you have an impulse control disorder or something, and then I apologize for not being sensitive to your specific needs.
it’s the truth, you could constructively ask me to explain my reasoning of such. it works both ways.
which I already attempted to explain some, but Paul only ever wants to hear what he wants to hear. Not that I’m obligated to explain in detail regardless. There are plenty of examples of more effective diffusers wrt less drag and more downforce.
at best it’s a not so efficient under-bumper wing.
.
consider the rear diffuser on the winning Ford F150 EV Pikes Peak vehicle, which could be applied to the center exhaust muffler by coping the diffuser tunnel around it tightly, or even piping through it with the muffler in the airflow for cooling:
.
Which I had attempted to address several years ago in another thread relative to cutting the entire rear bumper sides off in addition to the center bumper section. Which I think the rules prevented running a diffuser in that particular scenario or had a points/weight penalty, but the sides still serve a purpose with some informed thinking:
the way they did it 50 years ago:
.
the way they do it in 2024:
.
the fabricator who built this imo (not the car owner) .
.
But why would it be a benefit doing it like that (like f150e) and pushing the exhaust through it?
the OP runs a conservative angle of attach minimising the probability of flow separation as there is no flat floor to straighten it before the difusor (a steep exit angle/radius would add downforce with significant drag) . he is also running it close to the ground which is always better than running it from far away.
F150e runs a moddest angle. Which is needed at higher elevation due to lover density and the fact its grip limited not power, so expensive (drag vise) downforce is a benefit.
Just some opinion to contiue the discussion and exchange of theories and knowledge.
consider the rear diffuser on the winning Ford F150 EV Pikes Peak vehicle, which could be applied to the center exhaust muffler by coping the diffuser tunnel around it tightly, or even piping through it with the muffler in the airflow for cooling: ...
Which I had attempted to address several years ago in another thread relative to cutting the entire rear bumper sides off in addition to the center bumper section. Which I think the rules prevented running a diffuser in that particular scenario or had a points/weight penalty, but the sides still serve a purpose with some informed thinking:
the fabricator who built this imo (not the car owner) .
.
+1
This is the first I've heard about a diffuser thread you created. When I started this project and asked for help, that would've been a great time to present relative info so that others (and myself) may have an opportunity to educate themselves. People typically call that gate-keeping.
Regarding the spacial relationship and angle of the exhaust to diffuser / rear bumper wing, after 9+ months of this project being up, this was the first time you mentioned anything about it. I agree that their relationship does not look balanced and I would have requested the shop to respect this principle but this was unknown to me but not unknown to you.
A gentleman, friend, colleague, most acquaintances, etc would be more than happy to share said info because a healthy and productive citizen is more than willing to help their fellow man, American, etc. Lovingkindness very much falls into that practice and this unwillingness to help others is a big part of why the moral conscience of society has eroded to nothing. The concept of a civilization and the society that exists within it carry many implications established through humanity's collective history. Why anyone would intentionally withhold knowledge that helps others is beyond me and imo points to some type of motivation.
This statement holds truth because I specifically asked for help in the very first post (as well as the second for that matter) where you took time to criticize the bolt-on muffler, etc (no info or help willingly offered) and then went silent for a few months until you appeared again to mention I have no idea what I'm doing (again no help or info offered). This project needing help was no surprise to anyone but the thing I think you always fail to recognize, is that I do not work or have any connections in the automotive Industry and instead of offering up knowledge you posses, you choose to not be helpful. Any vehicle you seen built in this manner is typically owned by a shop, team or someone who works in the industry and I think you should put your opinions aside to appreciate the effort that the various shops and I have put into bringing this car to life.
ps- and thank you for finally taking a moment to clarify what you're specifically talking about. I just wish you were outspoken in a way which benefits the entire community as opposed how you choose to behave. If I had to guess, I think you spend too much time comparing, competing, etc and miss the part where some of us just do this for fun. There's a recent Option Video where Amemiya himself states how "back in the day, we just made cars to look cool." I also recall someone once saying that "jdm is all about emotion." I've always said I sought to create a work of art and all I'm trying to do is build a vehicle that honors jdm tuner style with no goals of podiums, trophies or cred.
But def a bummer the design and execution is flawed. It's hard to find good help these days, especially when you don't have any connects. If only someone could have told me sooner...
@MilosB to my lay understanding, it creates an effect similar to a "blown diffusor."
+1
But def a bummer the design and execution is flawed. It's hard to find good help these days, especially when you don't have any connects. If only someone could have told me sooner...
@MilosB to my lay understanding, it creates an effect similar to a "blown diffusor."
its not flowed.. the force is created on the underside and the attach angle is important.. if you want to improve on it make a "flat" flow in front of it... angle of muffler to diffusor is pretty much useless measurement.. (and I'm not theorizing and "extrapolating" data from Super 4.2 and other unrelated cars..
I wish I would have stumbled upon this thread sooner to give input.
I agree with Team, I think you missed two simple principles to gain a true effect of implimenting ground effect downforce. You will gain some with this, but not that much. A steeper, multi-radius angle would gain you a lot, and the lack of a clean air flow prior will be your largest hinderance. Additionally if you could have put the muffler further back at an angle with the exhaust being a more flat, open tip, it could have helped power the air out from the diffuser as well. Some racers will also add a small gurney flap on the back similar to a rear wing to aid air to remain attached to the diffuser surface before it escapes; granted your angle is shallow enough this likely won't be much of an issue for you.
Lastly the lack of closure on the exterior of the diffuser to the open air above it will likely cause very large amounts of drag.
Tack on the fact that the air hitting this thing will be so turbulent without a flat floor or at least fins to straighten out the flow before it gets to the diffuser, idk how well it will actually perform.
No one builds Rome on the first attempt though, give it another shot if you have the time and resources.
Downforce is nothing more than pressure differencials on either side of a plane. The greater the NEGATIVE pressure on the side closest to the road surface, the more downforce. I suggest gaining a thorough understanding of air-foils first and how they have been optimized for minimal drag but high pressure differentials.
I wish I would have stumbled upon this thread sooner to give input.
I agree with Team, I think you missed two simple principles to gain a true effect of implimenting ground effect downforce. You will gain some with this, but not that much. A steeper, multi-radius angle would gain you a lot, and the lack of a clean air flow prior will be your largest hinderance. Additionally if you could have put the muffler further back at an angle with the exhaust being a more flat, open tip, it could have helped power the air out from the diffuser as well. Some racers will also add a small gurney flap on the back similar to a rear wing to aid air to remain attached to the diffuser surface before it escapes; granted your angle is shallow enough this likely won't be much of an issue for you.
Lastly the lack of closure on the exterior of the diffuser to the open air above it will likely cause very large amounts of drag.
Tack on the fact that the air hitting this thing will be so turbulent without a flat floor or at least fins to straighten out the flow before it gets to the diffuser, idk how well it will actually perform.
No one builds Rome on the first attempt though, give it another shot if you have the time and resources.
Downforce is nothing more than pressure differencials on either side of a plane. The greater the NEGATIVE pressure on the side closest to the road surface, the more downforce. I suggest gaining a thorough understanding of air-foils first and how they have been optimized for minimal drag but high pressure differentials.
Please remember reading that there is supposed to be a full flat bottom very similar to what is seen in post #20. The vehicle was only released because I was told by the shop manager that they lost their main fabricator for an undetermined amount of time due to a serious injury. This being the case, the diffusor will be removed and postponed until the project can be fully realized.
@Fickert Hey thanks for dropping a few lines. Are you an educated / trained aerodynamicist or experienced with building custom aero for motorsports applications? If so, please share any relevant information and personal pictures for posterity.
I ask because there is no shortage of armchair engineers hanging around who claim to posses a certain skill set but very few actually back it up with tangible work and / or results. A lot of info is readily available on basic aero fundamentals but I'm of the mind to believe you can trust shops who operate in professional motorsports arenas. One thing I've learned during this entire build process is that this is definitely not the case and most shops greatly over-exaggerate their skills. So I ask all members to please direct your attention of improper XYZ (design, execution, etc) to those who consider themselves knowledgeable in a specific auto field(s) because I do not, nor have I ever claimed to possess such knowledge. Now I could have commissioned AJ Hartman or Zebulon to make a diffusor but I'd bet the same people would still make similar remarks; and at this point, for the cost of what I've already spent, would've been the more cost effective (and apparently respectable) route. Maybe I will, certainly doesn't hurt to write an inquiry. Something else I've had the displeasure of learning after hanging around forums, simply put, is you can't please people who aren't happy with themselves. The world could be a much better place but certain types of people are more concerned with personal agendas and ideologies as opposed to appreciating what is before them and graciously helping others in need, especially when they ask for it. Moving forward.
There's bunch of track days coming up and with both of my cars prepped and ready, it's time for some family adventure fun. I'm going to finally take my son (10 months in less than a week!) to the track! He loves wheels, just like his old man some might say, haha. Sonoma has always been so much fun getting to hang around eating, trail hiking, sight seeing and day tripping to Yountville, I can only imagine how much fun it's going to be. My wife is truly incomparable in what she allows me to put us all though (for real haha) so I've always tried to find that happy medium between my track day participation and family fun day.
Not done yet so there'll be plenty more to come, hopefully involving competent shops. Wish me luck or better yet, if you know any, please forward that info along!
I'll send you some info that may be of interest of to you.
Also I will more-so fall into the keyboard warrior category but with some understanding and backing. Last year I was heavily trying to get into a motorsport engineering position with Bridgestone (Mechanical Engineer), but ultimately that plan has fallen short due to my lack of real world experience vs other applicants. I have a friend from College on their motorsport team, they develop the Firestone tires for Indy. Really cool stuff. Heavily regret not taking part in the SAE formula team during college, my professional career I am sure would have been completely different (for the better imo).
All in all I've studied a lot and worked in a few CFD programs to get my feet wet during the process. Tack that onto the Aero courses I took I can say I at least have a mild grasp of what is going on with airflow, but with no real world experience which will always be king.
Also my son just hit 11 months and I totally get the desire to get them exposed to cars asap ha! As well as following Imsa, Indycar, and some F1, he'll be sure to like cars... I hope.
I'll send you some info that may be of interest of to you.
Also I will more-so fall into the keyboard warrior category but with some understanding and backing. Last year I was heavily trying to get into a motorsport engineering position with Bridgestone (Mechanical Engineer), but ultimately that plan has fallen short due to my lack of real world experience vs other applicants. I have a friend from College on their motorsport team, they develop the Firestone tires for Indy. Really cool stuff. Heavily regret not taking part in the SAE formula team during college, my professional career I am sure would have been completely different (for the better imo).
All in all I've studied a lot and worked in a few CFD programs to get my feet wet during the process. Tack that onto the Aero courses I took I can say I at least have a mild grasp of what is going on with airflow, but with no real world experience which will always be king.
Also my son just hit 11 months and I totally get the desire to get them exposed to cars asap ha! As well as following Imsa, Indycar, and some F1, he'll be sure to like cars... I hope.
Cheers.
It sounds to me like you're well on the right path and have taken the appropriate steps to gain access to desirable information related to your profession / industry. Best of luck in the future and I hope you're able to find a position where you can have your passion and purpose come together in an enriching work environment.
Congrats on the family! I wish someone would've told me how magical becoming a Father is! It's really the greatest experience in my life to date without question. He totally loves all his little trucks already (or possibly my sound effects that accompany them haha). And we might've watched a few hours of LeMans this year. It's all the noise I swear.
Since it sounds like you're not too worried about chasing lap times, I wouldn't worry about doing anything over again and just run what you have if you like it.
What I was hoping you'd notice from the link I posted a while back was that a little diffuser in a properly integrated system goes a long way. I'm sure the reference FD diffuser and the one now on your car does something since it looks like a diffuser, but it's likely that the airflow benefit-to-detriment ratio on a design like that isn't too great. I'm a JDM junkie too, but it's pretty clear that the vast majority of Japanese TA builds are not the example for proper aero application (or other aspects), especially when builds that do execute on a high level like Feras Q and Will Al-Yeung shoot up to the top of the leaderboards with little experience at Japan circuits.
If you do want to learn more, a lot of discussion is in FB groups. Make a burner if you don't have an account. I highly suggest joining the Professional Awesome technical group as topics like this have been discussed ad nauseum. You may even find an rx8 racing group that's a little, or a lot, more active than ol' 8club
Re: the Esprit wing, there's a solid chance that your car will understeer like a pig if the front doesn't have anything to overcome the wing and the diffuser. Is it the 052 model?
Since it sounds like you're not too worried about chasing lap times, I wouldn't worry about doing anything over again and just run what you have if you like it.
What I was hoping you'd notice from the link I posted a while back was that a little diffuser in a properly integrated system goes a long way. I'm sure the reference FD diffuser and the one now on your car does something since it looks like a diffuser, but it's likely that the airflow benefit-to-detriment ratio on a design like that isn't too great. I'm a JDM junkie too, but it's pretty clear that the vast majority of Japanese TA builds are not the example for proper aero application (or other aspects), especially when builds that do execute on a high level like Feras Q and Will Al-Yeung shoot up to the top of the leaderboards with little experience at Japan circuits.
If you do want to learn more, a lot of discussion is in FB groups. Make a burner if you don't have an account. I highly suggest joining the Professional Awesome technical group as topics like this have been discussed ad nauseum. You may even find an rx8 racing group that's a little, or a lot, more active than ol' 8club
Re: the Esprit wing, there's a solid chance that your car will understeer like a pig if the front doesn't have anything to overcome the wing and the diffuser. Is it the 052 model?
Yeah a few friends have also made the recommendation to just run with what I got. If I'm being honest, it was one thing to see it mocked up on a lift as opposed to on the ground with wheels on, etc. It's possible with the new wing mounted to compliment / offset some of the proportional relationships I might like it more. But as-is it just looks kinda funny imo. Maybe if I had been able to work more hands on with the fab process it could've turned out differently. It's been really difficult to find ethical and / or competent shops to help me with almost everything.
Totally agree with you on the jdm TA car execution and wow Feras Q's car is a serious machine. I've been a fan watching him develop his ride for years now. Insane lap time he threw done at Tsukuba imo. And sounds like I'll have to join some FB groups so I can learn to start taking a few things back into my own hands.
Yes it's the 1640mm 052. I don't recall offhand what the gt depth or stand height is but I was hoping to work with the previous fabricator to find an ideal placement for chassis mount. I'll grab the height from the stands they sent and the foil depth in a few days. Regarding understeer and driving dynamics, turn-in and exit have always felt neutral with very little input required while running the Odula GT (57" wide, 10" deep, 6.5" stands) on various wheels (18x9.5 255/35, 17x10 275/40, current 17x10 255/40) and track alignments. Something worth note is that the 052 is only 7.48" wider than the Odula (depth tbd). I'm sure where it's placed (height, how far back, etc) is the largest influential factor on how much effective df it produces but I can't imagine it would disrupt the balance so much as to cause an issue (I'm not planning for anything crazy). Long story short, there was supposed to be a modest update to my front end to go with the flat bottom, etc to 'complete' this next installment.
Got a chance to measure the 052 yesterday but forgot to grab the weight. Depth is 12.5" (I've heard of up to 14") and the stands are 9.5." So the foil itself isn't too much larger when compared to the Odula imo. It might be worth mentioning that the Odula has the '3D' shape with .5" integrated gurney flap (1.5" on the side plates) molded into it whereas the Esprit is purely flat and the area behind the '3D' shape on the Odula is a really nice curved radius (imo) which leads into the flap. I'll measure each side plate as I'm sure they're different proportions as well. The Odula is 8" x 5."
Here my untrained natural instincts would lead me to believe that certain trade-offs between the character of each GT wing would more or less be 'comparable' in driving experience. So not to be such an abrupt or drastic change to the chassis that you need to relearn and adjust to the altered / new driving dynamic.
But I could be totally wrong and I'll be sure to share any and all experience. Hoping to get it installed and put a few laps down soon.
Some progress. I had the good fortunate to find someone really talented to help me out. My mount kit specs will be available for the 052 for anyone interested. At some point in the future I'll get a real aero consultation and continue the flat bottom with real numbers to back it up.
it is obvious that with an full flat flor it works better. Nobody normal would question that (at least I hope).. the argument at least on my point was that what he did was not that bad. And he can continue working with it as he can.. There is always better way to do something and that also depends on the extent as to how far one can stretch $$$ and also how much they want to modify the body and its components.
imho 1 very important aspect he did very good was that he didn't mount it with overly aggressive angle which is very common mistake.
Some slight progress and I expect this to be the final stretch as far as getting the wing mounted goes.
Parts are back from the machine shop and ready for install. Personally think it turned out really well and love the brushed finish. Just waiting to coordinate schedules with the fabricator; definitely before the end of the year.
