scottdh20

DavidNJ

Can you post more pictures of the radiator/intercooler duct in the hood, the intercooler/radiator mount, any sealing/ducting on radiator/intercooler, and any diffusers used on the front splitter? What size tires are those?

scottdh20

i will try to dig up through some pictures of what i can find as far as mounts and ducting. i attached a couple i have on my phone. the rad mount is just some square tube utilizing the stock top mounts for a mounting point. then some flat stop triangulated to the stock rad support with some holes rivnuted into it for mounting the top is just some aluminum flat stock i bent in a break and used some stock m6 holes that were nearby to anchor down and used pcv rubber grommets from oriellys to isolate it. all the ducting i used some metal from the ducting section of home depot, cut riveted it and then used that metal ducting tape to seal all the joints. where the duct meets a cooler i have the single sided 1/2" thick foam tape for insulating doors/windows from home depot. other gaps i used home window a/c insulation foam to fill gaps. the previous picture you can kind of see the bottom of it and it swoops down and attachs to the radiator mount. there is a center duct that gets sandwiched between the coolers and the top section is connected to the hood so i have acces to the entire engine bay without removing any ducting. the angle out the hood is not ideal aerodynamically but space limited with the cold side charge piping/bov its as good as i could get it. i did 4 laps with the turbo screaming and never saw over 3bars with the modify coolant adapter which means it stayed under like 190* the entire time

front splitter is diffused but i broke it pulling onto the alignment pad at the track...oops. currently the diffusors are made from sheet metal but talking to professional awesome they are going to be coming out with a smaller version of there large diffusor that will work with s2000's which im really excited for. i have been semi-consulting them for alot of my aero concerns.

konig stepped up as a sponsor this season and im running the 18x10.5 +25 konig hypergrams and the tires are 285/30r18 re71r square setup (class max width for rwd) it was a bear to fit, rears is tight with the asm, fronts i would have been fine with voltex but the wait on a set of voltex/shine fronts wouldnt have been here in time so some cheap ebay $25 3" flare did the trick. i had to head the mounting points to get them to sit on the s2k's fender, not perfect but meets the rules requiring the tire to be covered viewed from above

scottdh20

also on top of the fender vents i have the front fenders spaced out to help evacuate the air in the wheel well unfortunatly dont have a great picture of it.

DavidNJ

Umm...very interesting! Thanks for the detailed answer.

You were cognizant of the lift/drag from the cooling system. Do you wrap the ducting all the way around the radiator to force both the radiator and intercooler through the hood duct? With the radiator sealed off, where does your air filter draw from? What temp is that air?

On the splitter, what determined the depth of the lip? I is much shallower in the front than on the sides. Did you have the chance to do a CFD, flow visualization, or load measurement (presumably front suspension deflection) on it? Did the diffuser size interfere with the brank ducts?

Why did you go with +25 wheels? My rough calcs indicate a +47 would have probably fit, tucking them under the fender by nearly an inch more. Not sure what you meant by "the front fenders spaced out to help evacuate the air in the wheel well". Wouldn't you have wanted the fender behind the tire visually from the top to tuck in as closely to the inner fender as possible to route the air around the sides of the car? The WTAC cars use inboard coilovers I believe in part to achieve a clearer airflow there, some even with bargeboards to assist.

scottdh20

from a flow standpoint a stacked radiator/intercooler and oil cooler angled with the top forward will achieve the best flow in terms of drag/lift. downside of stacking is reduced cooling efficiency. i still trackday the car and wanted something capable of more than 2 laps. i took a small loss in terms of drag but gained an incredible amount of cooling efficincy. this should allow me to do 20+ minute sessions with no cooling issues. nothing was cfd but more designed around theory and i consulted a bit with professional awesome and ran my designs and idea by them to get constructive critisism on the design, he suggested stacked but did verify that if i chose to do v-mount to fully seal the system, although not aerodynamically the best it could be was a good compromise. by fully sealing the system it traps the incoming air from from pressurizing the engine bay and flowing under the car and instead sends it all up and over the car. this setup will produce a reduction of lift (downforce) in its current state vs stock by a good amount.

air will still enter the engine bay around the engine as the splitter can only go back as far as axle centerline. there is also a rather large hole next to the headlight into the fenderwell right where the filter is placed. i will be adding louvered vents further back on the hood to help more air and heat escape. for being turbo'd and no lovers currently we were very suprised it wasnt cooking under the hood, so the low mounted turbo seems to have worked as theorized

the splitter is not optimized for sure. ran low on time and i chopped down a old splitter from last season that was 3" at the front and was more of a hammer head shape. i chopped it down on the sides to meet the 5" rule. i will be making a new splitter to maximize the 5" allowance. and the ducts i measured my available space before making them. no interference at all. pro-awesome gave me some "general rules of thumb" to abide by as far as tunnels go, so although not optimized they are still highly functional. i can update this thread when i make the new splitter aswell. should be within the next month or so

+25 wheel choice had to do with the sponsorship. i knew if i wanted to take a stab at street modified i would need to be running max allowed tread (285) so the 285/30r18 re71 was the no brainer being limited to a 200tw tire. 18x10.5+25 is the best fitting flow-formed rim for our chassis they offer unfortunatly. i did send them some feedback that making a couple rims in a higher offset would be very marketable to several chassis not just s2000's.

as for the fender there is many ways to skin a cat. i could run a fender like j's, i could cut my stock fender and fold the lower portion inward, or the inner structure of the s2000 isnt terrible and can be spaced. basically you leave the top bolt as normal but remove the bolt in the door frame and the lower two bolts. make a bracket to extend the bottom of the fender outward several inchs. this creats a opening in front of the door(like a widebody) as the fender physically is further outward than the door. the allows for the pocket of air that gets traped behind the wheel and infront of the door to get evacuated. in the future i would like to extend my side skirts out aswell that will help that evacuated air from slipping back under the car and creating additional lift. i also have the top of the fenders vented but with such large tunnels was concerned the vents wouldnt quite be enough.

this is not a wtac car, far from it, im just a track rat that got into some time attacking. all self funded and lots of diy projects. you would be surprised what you can do at home with simple tools in terms of improving aero. they have big budgets for cfd analysis and aero engineers working on their cars. i talk to a few aero engineers and do lots of my own research on what works, i mimic what i see with a pretty decent understanding of what it does good and bad for airflow. i keep my designs relatively basic and in the middle of the road. if i attempeted to go extreme on any of them it would be very easy to make things worse, stick to the middle and 99% of the time things are improved, maybe not optimized but greatly improved never the less.

i did have some cfd tests done on the j's/voltex wing and although very very efficient isnt quite the df producer im going to need even with the custom end plates(31% increase in df with the cfd'd end plates iirc). likely one of the next big aero upgrades will be a better rear wing and getting it chassis mounted. but looking at the data the j's wing is a great wing for a n/a s2000 with a basic 3-5" splitter. extremely efficient with very little drag.

Charper732

Jesus, those diffusers are HUGE. Def. Update us with the new splitter. Care to share some of those general rulea of thumb you learned from them?

DavidNJ

Very few here spend the time to seal and duct the radiator/intercooler over the hood. Possibly one of the biggest moves you can make to reduced drag and lift. I imagine more than most front splitters. But you are still venting the air from the diffusers there so getting it out is key. I haven't hung a stock car body in a while, but Five Star used to recommend pulling the fender behind the tire as far in as reasonable to help air exit behind the tire. It is simply a matter of keeping it from getting under car and keeping it along the side of the car. You should be commended for your attention to this critical aero area that just isn't supported by the S2000 aftermarket.

At your power level and fuel (400hp on E85) I would have thought you don't have an IAT problem but could have a cooling issue. Since the cap isn't doing anything, I would have sealed the radiator...none of the stock car radiators have caps, just header tanks like your build.

The Viper ACR splitter could give some splitter ideas. This NASA racer has a business building some pretty fancy CF aero parts: https://ajhartmanaero.com/blog/split...ors-explained/ The WTAC is interesting because the rules aren't that different than NASA and as you said, lots of thought and money go into the top few cars.

I would have focused on the aero and the suspension...especially getting the geometry right on a lowered car. It looks like you may have the skillset to make a fabricated suspension with either different mounting points or different spindle (it all could be done with the spindle).

The +25 wheels should have a pretty big scrub radius. Are you getting any kickback and tramlining?

Everything is relative. I can't comment on the ark, and I would prefer flush fasteners (see Carroll Smith's Prepare to Win, which I diligently xeroxed when it appeared as a 7-part serial in 1970 copies of Sports Car Graphic), or given that this is 2019, use an adhesive.

scottdh20

i have had the intentions of boosting the car for the past few years so i have done my homework, lol. have track buddies and connections i have made over the years who specialize in many different fields like tuning, aero, engine building, suspension, etc is huge. share a beer with a guy in the pits and you'd be surprised the amount of free info they will give out when i set out to do something i typically spend a decent amount of time researching from multiple sources best practices, what works, what doesnt and overall do the best i can with what little budget i have. pro-awesome, aj hartman and a few other aero guys have really been pumping out some great youtube videos and articles over the last year or two that is getting this knowledge in the hands of the grassroots guys. i run in the gridlife series and 5 years ago some cars on podium didnt even have splitters, now your not on podium without some pretty trick aero devices (splitter tunnels, splitters, diffusors, wings, cfd endplates, etc) time attack is growing pretty well here in the states.

the thought process behind spacing the fender was a simple one. at the time i originally did the mod i had mint fenders and the mod allowed me to vent the air introduced into the wheel well from the tunnels without cutting or modifying the fender in any sort of permanent way. professional awesome used this very same technique on their own time attack car in the past with good success. to put into perspective of just who professional awesome is if you havent heard of them at #gridlife track battle this past weekend the professional awesome evo piloted by tom o'gorman took the overall win over both james houghton in his type r and will au-yeung in the vibrant civic (the same one that just set the tsukuba fwd lap record and the 4th fastest car to ever go around tsukuba). they definitely have some credibility.

yes the cap to the radiator is sealed but i have a coolant swirl pot in the strut tower with a tradisional radiator cap and stock overflow. never saw over 200* on track

oh man do i wish i had the budget for spindles they are amazing and can do wonderful things for suspension setup. maybe someday but likely not just have to work with what honda provided lol

the wheel/tire combo was just installed prior to this event, i cannot speak to much on them yet as i havent really pushed it hard enough in corners where i would have ran into issues. i will say the #1 podium in my class is a s2000 on the same wheel/tire setup

ultimatly id like to nail down a splitter design that works well and i will make it out of fiberglass with built in tunnels to keep airflow smooth. button head screws although not ideal are far less harmful than hex heads and adhesive wouldnt have likely worked well with the materials i used. ajhartman also used button heads in making his splitter, you can see it in this video , i figured if its good enough for hartman it should be fine for me aswell. as to the size its all relative to the amount of downforce your looking to make. honestly for the amount of wing i have they are probably a bit oversized, but i also made them earlier in the year when i had planned on a different wing. as for the tunnel pitch i was told no more than 12*

DavidNJ

Actually, all of the downforce is concentrated in a relatively small area directly in front of the start of the diffuser. The key to the diffuser is to keep the velocity high at that point. It seems all current F1 cars and most of the GTs that have flipped and shown us their diffusers have concave shapes with a nearly vertical edge where it begins. I have no ideas what parameters govern that and don't have a running CFD to play around with (project #851 somewhere after TIG pulse welding).

Note that Hartman also has a diffuser between the bodywork and the endplate. If further videos show he is short on instrumentation to measure its effectiveness (minimally a low-frequency wheel travel transducer, in contrast to the high-frequency ones needed for understanding the shocks. He hasn't adapted his spring rates or damping to the downforce which seems to have resulted in porpoising. I have no idea why he using a twin-tube shock, obviously another problem (I don't think there is a serious race car anywhere that uses a twin-tube shock unless it was required by the rules).