juntsky

well...you're posting on an open forum, where people voice their opinions. Would be far easier for me to say "those side diffusers look stupid and probably don't offer quite the benefit you think they do" but I tried to subdue it by saying it's not to my taste. What do you expect the reaction to be when you post a picture of a part you're going to add? "Do you think this will shave .0001s from your lap time at willow springs? why do you think this? OMG i need moar track focus!"

Be realistic.

Now, since you pointed out the hump on the Amuse R1 and claim it would be beneficial to maintain that shape with a bigger diffuser, it makes me wonder why Amuse wouldn't retain the shape with the legalo. Also curious now that I bring up the bumper if the indention in the fenders behind the vent has a specific airflow function. I would think it does, but I'm not sure what the benefit would be.

114_ap2

Have you ever measured rotor/caliper temps after a track session. Also, has your pad life increased? I have a pretty similar setup to yours and just ordered some Spoon calipers.

boyguan

i like how it looks, i perfer it to flare out a bit more at the end but either way looks good.

that 04 bumper will look good when you get it on andrew

andrewhake

Sorry for the ridiculously long post in advance, but for me to try to explain my thoughts on this I have to use a lot of words, haha. If I knew more about it I could probably due it more effectively, but who cares, this stuff is very interesting for me to discuss. Hold onto your butts, were are going in!

I VERY clearly stated I don't think any benefit they might provide is extremely minimal. I VERY clearly stated 99% of the reason I added them to the car was because I like how they look. If you would have read my post you would have known that. I know they are stupidly long sometimes but if someone wants to critique what I am saying they should at least have the common courtesy to read it fir.t I VERY thoroughly explained why I do think there is a small benefit, which can be verified by anyone who reads a basic book or article on aerodynamics. It's extremely annoying when people pipe up with things like, "I don't think that does anything actually." Well great, good for you, if you want to convince me of anything tell me why. If you don't have any good evidence to convince me then you are wasting your and everyone else time. I like discussing this stuff, and someone saying they think something does nothing because off some offhanded remark they read somewhere else just isn't interesting.

The R1 bumper was designed alongside Polyphony Digital back in the day who spent some time with them doing CFD. This type of shape on the bottom of a front wing or splitter is very common in high level motorsports and as I explained is a very common shape in aerodynamics period. You will see a similar shape on the ASM front under tray actually. I am by far no expert in aerodynamics or even particularly well versed in it, but from what I do know I would have definitely included the same hump and little tire diffuser spats that that R1 bumper has. As well as lowering the splitter on the Legalo bumper by about 25mm or so. Arvou did this on their demo car (RIP, thanks Orido...) by 50-75mm or so from the looks of it. Which should increase the efficiency of the splitter by a good amount, placing it closer to the ground, speeding up the airflow underneath it, creating a more effective lower pressure area. It also has a splitter with quite a lot larger surface area than the R1, but that has the downside of being harder to drive day to day and to accommodate that they probably place the splitter higher up off the ground for that reason. If you look at the R1 and the Legalo appears to sit higher off the ground. And the main reason for that is the lack of that hump (as well as not having the little tire spats). Simply comparing both I would say the Legalo is likely more effective, but incorporating all of the good elements of both would make it even better. If money is no object I would lower the splitter on the bumper like I mentioned, and also incorporate something like the ASM front under tray which has a more considered shape.

I think the Legalo fenders are an excellent design aerodynamically. Pulling as much turbulent air out of wheel wells as possible is a very common and effective way to increase front downforce. From what I have reasearched the front splitter and and good vented hood designs will have the largest impact on front end grip, but all these little detail elements definitely contribute as well. You see this on basically every high level time attack car and race car in the world, and even on production cars like the GT3 RS and many other more exotic models. Figuring out what actually "works" is extremely difficult. It isn't just a matter of popping something on the car and going out and trying to turn lap times. Lap time is a great data point, but it is EXTREMELY inconsistent from day to day and even from hour to hour. Track temp plays such a large role int this it becomes difficult to actually determine what works and what doesn't with getting into CFD and wind tunnel testing. And often what clearly works in CFD or the wind tunnel might not consistently work on track. There are a crazy amount of variables. Visually I prefer something like the GT3 RS front fenders, but who cares really?

I was looking at this the other day on my car actually with it up in the air and the wheels off. With the "brake ducts" on a front bumper like the Amuse bumpers and many others with no brake ducts installed, the air that comes through comes directly into the backside of the fender liners in the wheel wells. This probably creates a pretty large high pressure area inside the bumper itself in front of the fender liners. With nowhere to exit that air just builds up and gets turbulent inside there and creates drag, but allowing it a place to escape could probably create positive results and even contribute to reducing front end lift more. Bumpers like the original Spoon Super Taikyu and the ASM IS-11 have venting on the corners of their bumpers specifically for this reason I would guess. And it's stupid, but even the way people roll fenders and trim fender liners likely allows all of that air to escape at very high speeds. A sort of mickey mouse version of openings on the fender or louvres like you see on many race cars, or a much more open fender design like the J's, Spoon wide fenders, etc. Removing the fender liner likely creates a massive amount of turbulence (which leads to more lift and drag), as way more air comes into direct contact with the face of the tire, stuck in the large rear section of the fender itself, and so on. Will it keep anyone from setting a fast lap time or winning a race? f@#k no? Is it something that should be considered when experimenting and refining your car? Why the f@#k not? All of these small little considerations add up and when very well considered can definitely contribute to differences that can be felt by some drivers and taken advantage of. If everyone just ignored it you wouldn't have a majority of the crazy race cars we see today.

andrewhake

PSI is a major service center for Ohlins, they can rebuild and replace any parts you would ever need. Rebuilds aren't super cheap, but during a rebuild they can easily revalved for different rates to a limit. Personally I have a friend (that most of my parts purchases go through) who already had the ball rolling on getting a good revalved option from Ohlins made for stiffer springs, so I can get a very good deal on them so I will likely just end up with another set temporarily until I sell my current setup, or just hang onto it as a backup or whatever. My current set have nearly 20,000 miles and still feel fantastic. I don't notice any difference between the damping now and when they were new.

I think 700lbs/12.5kg is the sweet spot for a street car that is driven pretty hard on and off track. My current setup feels great, but going onto very grippy tracks it can be pretty clear the amount of body movement and amount of time it takes to transition could use a slight improvement. It makes the car easier to predict and makes the driver more confident in all of their inputs. It won't inherently make the car faster unless the driver can take advantage of it, so this is very driver dependent. Some drivers might be faster with softer springs, some might be faster with much much stiffer springs. But without trying it out there is no way to know. ASM actually provides 700lb HyperCo springs F+R on all of their ZF/Sachs damper setups out of the box. They run much stiffer springs on their dedicated time attack cars, but there is absolutely no reason to think that a good damper can't easily control a 700lb spring on an S2000. Honestly I think I could put the springs on the current dampers no problem, it would just shrink the effective adjustment range and would require me to sacrifice part of that range, so might as well do it the right way. This also allows more freedom if I want to increase or decrease the rates again later on.

I am not convinced that stiffer springs on the front make a useful difference under braking or improve the balance of the car. It doesn't makes since to me that a setup with 10k/8k springs would feel any different under braking than 10k/10k springs. It might change the way the car feels getting back onto the throttle. But I haven't spent a ton of time driving any car on a setup like this, and I don't have any desire to because I absolutely love the way the car rotates into a corner and the way how smooth the transition is into on throttle oversteer. I suppose it would be worth trying out to see if I could turn faster lap times this way, but I am much more comfortable with the car smoothly transitioning into oversteer than I am with it understeering slightly and having a more snappy transition into oversteer.

Dreaming_S2k

Sweet Jesus I love this thread...both the car and the discussion. Pretty much the way you've articulated the positive effects of higher springrates makes me want to look into a swift spring upgrade for my KWv3.

andrewhake

Pad life is definitely increased! I haven't had the chance to take measurements on rotor/caliper temps unfortunately. I wish I would have picked up an IR thermometer before I swapped over. The biggest difference that I can notice driving is how quickly the entire rotor/caliper/pad setup cools down after getting hot. Which I noticed most after switching to the new calipers. When I bed in pads. I get them EXTREMELY hot, to the point that they start fading badly, so I get a really good transfer layer down. The amount of time I need to cool the brakes down in between bedding cycles is much less with the new calipers. The pad wear is noticeably more even and the pad edges never start to crumble and fall apart like they would on the single piston calipers. With the stock calipers I could have pads that could develop a small chunk on one of the leading edges, which obviously reduces the effectiveness of that pad, and you end up tossing that pad earlier than you would if it was nice and even. The pad wear is dead even, very consistent, and so far allows me to stretch the same Winmax W5 pad further than I was able to on the OEM calipers.

I really like to think about and theorize on all this stuff and look at data, but when it comes time to actually spend time collecting all this data on the track during a busy track day I tend to avoid it I have found. I really prefer to just concentrate on the driving and not the car. Once I get more time at more tracks I will probably start getting more into this stuff though.

wingz

andrew,

i'm not speaking within the context being spoken here, but i will say that some of the best feedback i've received about anything related to me, have been unsolicited feedback. this has nothing to do with cars (yours or mine or anyone elses), but just in life. you can either agree or disagree with their comment, but i try to be open to all feedback. good or bad. there is almost always something you can take away from their comment. even if you don't like it.

with that said, i also do get a bit annoyed when someone who points something out just for the sake of putting someone down. its not constructive nor helpful to anyone.

your reasons on adding side diffusers makes sense to me. no need to be defensive. just acknowledge and move on.

Ricky_Flowers_

Page 90 of this thread summed up in a gif:

andrewhake

Thank you very much for saying so! It is good to know I am not just rambling on to myself here. And be discussing it here help me understand it better myself. It's odd with cars and parts and stuff because everyone sort of builds up an odd bias for certain things, and I definitely do that as well. But everyone generalizing so much and just saying this doesn't work that doesn't work, this works, that works, doesn't really mean anything without getting into the details.