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i have a decent grasp of aero, a super long way from being any sort of expert, i leave that work to the experts lol. i know enough to not jump int oprojects blind and do lots of homework and consult with some experts in the field and show them the rough ideas and tweak per their recommendations. far from ideal or perfect but pretty good jump for the world of grassroots time attack. i never intended this to become a aero thread lol or i would have posted in the racing/competition sub forum. there is alot of voodoo and black magic i dont full grasp with aero and its pretty easy to make your car worse. end goals would to have a cfd of my car at some point and a legit aero package designed and implemented for now i will keep it simple and just try to keep things middle-ground where things work but not optimized. step in the right direction without going backwards so to speak.
my intention for this post was to highlight the use of holset (hx35) turbos on out cars and give a little insieght for others to be able to find searchable content. im my quest i found one or two posts and that was about it. i feel the turbo is a great match for our engine with folks looking for the 4-500whp range which seems to be the vast majority of s2k owners. kinda the limit of a act/oem clutch combo, much over and the trans/diff become disposable, fuel system needs improvements, etc. the turbo's are also super cheap and commonly found on forums, facebook marketplace and craigslist for sub $200. the quality of these turbo's is very very good and are designed to work for hundreds of thousands of miles. 400whp, full boost by 4k and holds till 9k sounds like a perfect little turbo for a f20/22
But the turbo question is not just the cost of the turbo, but the custom fabrication. On pump gas without opening the engine, 400whp may be on the high side. SOS is showing 385whp at 10psi of boost. At those levels most sacrifice the performance of the exhaust manifold for better packaging. And many (most?) or looking for a reliable kit with the bugs worked out. Most willing to engineer their own solution including fabricating a custom manifold and intake tubing are often looking for more. While the turbos can get expensive, they are still less than 1/2 the cost. A new BW SX200-E is less than $1000.
The conversation switched to your aero because most people seem to fabricate their own splitter and radiator ducting, and yours is more involved and toward a comprehensive solution than most.
A new business starts with an idea. The key to success if often adapting to the part of the idea or related concept that the market is buying. In the TV show Silicon Valley, an original theme was that a wannabe tech entrepreneur developed a music app, and without realizing it had developed an embedded a class-leading compression algorithm. The value of the algorithm far exceeded the value of the app.
It is unclear if anyone will jump to a Holset turbo. However, I wouldn't be surprised is some are already trying to duplicate your splitter!
But the turbo question is not just the cost of the turbo, but the custom fabrication. On pump gas without opening the engine, 400whp may be on the high side. SOS is showing 385whp at 10psi of boost. At those levels most sacrifice the performance of the exhaust manifold for better packaging. And many (most?) or looking for a reliable kit with the bugs worked out. Most willing to engineer their own solution including fabricating a custom manifold and intake tubing are often looking for more. While the turbos can get expensive, they are still less than 1/2 the cost. A new BW SX200-E is less than $1000.
The conversation switched to your aero because most people seem to fabricate their own splitter and radiator ducting, and yours is more involved and toward a comprehensive solution than most.
A new business starts with an idea. The key to success if often adapting to the part of the idea or related concept that the market is buying. In the TV show Silicon Valley, an original theme was that a wannabe tech entrepreneur developed a music app, and without realizing it had developed an embedded a class-leading compression algorithm. The value of the algorithm far exceeded the value of the app.
It is unclear if anyone will jump to a Holset turbo. However, I wouldn't be surprised is some are already trying to duplicate your splitter!
when I start a project I tend to do alot of homework, consult with folks i've made friends with at the track throughout the years that "specialize" in whatever project i seem to be tackling. lots and lots of reading online, books, etc. Alot of it comes from trying to milk out the best end product vs time/money spent for the highest return. Im a track rat that became a time attack hobbiest, no i dont expect to be a front runner in most of the series as i just simply dont have the budget required to be a top dog. its not just car, its entry fee's, travel expenses, out of state events, consumables, etc. but you can make a name for yourself and be pretty competitive even in the world of time attack on a budget and thats more or less what im trying to accomplish. i'd like to be knocking on the doors of podium times. with the splitter the info is out there, lots of it, if you use your head a little you can make some pretty decent stuff for really cheap. i lean towards plywood vs composite simply for cost. i have the skillset to make a composite splitter, which i may in the future but honestly i go through a couple a year and bolting $500 in raw materials and dozens of hours of labor doesnt make much sense when plywood can get me 95% of the way there for 1/8th the cost. but i tend to do little things like profiling the leading edge of the splitter, tunnels, overall shape, and some other little tricks to maximize what wood can accomplish. my splitter mounts incorporate turn buckles to be able to adjust the pitch of the splitter in a matter of minutes similar to a apr gtc200 wing(and exactly where the idea came from lol) it also gives room for adjustment if i have a minor off and tweak the mount to adjust it back into place to continue racing without tearing the entire front end apart. i was really bummed that the splitter got damaged pulling it onto the alignment pad, it was probably strong enough to run but 3 or so of the ply cracked and if it did completely break the chance of it going under the car and causing damage was too much to risk and i opted to shake the car down without it. i was quite impressed however how planted the car still felt up front which leads me to believe the hood duct is functioning very well and doing its job well. ideally i will likely get a splitter design that works really well figured out in plywood and then make a mold of it and make a composite version to test
later in the season i will be making a rear diffusor and depending on how testing goes i may be able to benifit from larger tunnels(what these were more or less designed to use.) over winter i have plants to make some pretty trick sideskirts as well, they should both produce downforce and keep air from slipping under the car.
but you can make a name for yourself and be pretty competitive even in the world of time attack on a budget
There are very, very few people who get rich racing, a few who make a living. In the pro levels, it is as much about marketing as it is about going fast. If you were a scratch golfer at a local course you'd probably have a more people aware of your accomplishment.
You are absolutely right, the actual track time is very expensive. Transportation, hotels, entry fees, tires, fuel, and other consumables. Not to mention crash damage and equipment failure. It is the reason spec racing classes (Spec Miata, Spec Racer Ford, Spec E30, etc.) are popular. Before the rise of the spec classes, tightly controlled classes like Formula Ford and Formula Vee were the popular low-cost entry. Given the high cost of track time, big stuff like the aero goes a lot faster if you can look at meaningful data or images (e.g. strategic GoPros, flow vis, etc.). It also helps to have parts you may need (e.g. stiffer springs and the tools to quickly change them and adjust corner balance) readily at hand.
The best way to go racing is to have a lot of money or big marketing allurement. As I write this Keating Motorsports' Ford GT is leading the LM GTE AM class at Le Mans. Ben Keating is now 47. He began racing 13 years ago when his wife bought him some racing classes as a present. His father owned a dealership, and 4 years earlier he had bought his first. When he started racing he owned 4. Now he owns 10. There is a Ferrari F488 running mid-field in the same class with three female drivers. If you're famous or rich, racing is easy. And you get to hang out in an air-conditioned motorhome with a shower at the track.
The rear diffuser will do something, probably. In F1 I believe they are 40%-50% of the total downforce. I doubt it will be that much here. Also, in F1 the low-pressure area is in front of the rear wheel centerline, here it will likely be after it making the balance different. The only track-adjustable aero component will likely be the rear wing, so tuning will be limited, especially if the springs are too soft leading to significant pitch angle changes. Hartman has a product for that (https://ajhartmanaero.com/modular-diffusor/) and a blog on his work developing it (https://ajhartmanaero.com/blog/project-crusher-part-2/). You guys seem to be on the same wavelength; have you given him a call?
Sidebar: In F1 and some endurance cars the rear diffuser is concave, with a show angle upwards at its leading edge. I saw a CFD of this years ago, and it seemed to work best with some specific parameters. But it has made its way to some top draw race cars.
Sidebar: The current WEC GTE rules are very specific on rear diffuser size and location. They all look like the one Hartman is selling. Their rule limits it to 100mm behind the bodywork, and they all use that.
i havent talked to much with aj hartman. like i said in an earlier post i have and do talk quite frequently with professional awesome. another company making diy aero stuff and offers similar services as hartman and has some credentials and whatnot backing his claims. they have been instrumental in alot of the aero decisions i have made. i'll never make racing pay me, im aware of that i'd have a better chance making it onto a nfl team having never played football in my life. as anyone who has this hobby can attest there it is a very expensive hobby, making partners with some companies can definitely lessen the blow quite a bit. but nothing is free, you gotta work for those companies in return. i havent done much in the way of sponsors simply because i havent wanted to commit so much time off the track to said sponsors. at some point i will likely delve into that arena but for now not having strings attached has its own benifits.
the series i run in (gridlife street mod) i am allowed aero within 5" of oem bodywork. so the diffusor can only protrude rearward 5" or 127mm. when doing some diy aero my motto is to stay middle ground and not push the limits of what should work. am i leaving some potential on the table? absolutely. but aero is a funny thing and just because something in theory should be beneficial doesnt always mean it is. there is all kinds of trick things you can do, but if you keep your designs reletively mild/moderate you have a high likely hood of them producing net gains. its very easy to build something too aggressive that actually hurts performance. and without a full cfd model its very hard to tell and even harder when you may be changing multiple aero devices at once to know what did what. some simple gopro and yarn tufts are as about as high tech as i have gone lol, not perfect but lets you know what your doing is headed in the right direction.
my class does not allow flat floors. splitter and diffusor may only extend to axle centerline. i expect that the diffusors performance will be severly hindered however net gains are still there for the taking.
so the orginal splitter got damaged pulling it onto a alignment pad, so i decided to scale back the splitter diffuser size after some consulting with pro-awesome and realizing the first version was simply to large for the amount of rear downforce the j's wing is capable of. so i made a mold to make some smaller diffusers from plywood, it worked pretty well id say. able to recreate as many of these little guys as i please. i may make a further revision and reduce the angle a bit more. but they also had to be cut down shorter to fit so im not utilizing the entire molded tunnel.
here you can see the bulk of the new splitter design. you can also seen how i maked my chassis mounts the turn buckles allow me to adjust the pitch of the splitter. the driver side mount slightly interfeared with the rad mount so i trimmed it back a bit.
not nessecary by any means but i still like to drive my car around and the maybe 2lbs i added back in was worth it to have a cleaner looking trunk, trunk carpet back in
sweet roller shot from a event. you can see most of the splitter design is 95% complete here. i have since added steal cabling from the side of the bumper support to the outer edge to support the sides of the leading edge. going out the sides of the bumper support helps to support it from side to side movment.
i am trying to get back on track for one more trackday, i have tweaked the setup a bit to keep dialing it in, i think i have it close. i had it retuned, just a etune/street tune as i need to rent some dyno time to let my tuner log in and finish doing the fancy stuff. will be going with a smaller wastegate spring, 4 port boost controller and doing some trick stuff with boost by tps. this should help eliminate wheel spin quite a bit on mid corner and corner exit. grip from the 285s is still just jaw dropping, and havent quite found the limits mid corner, just keep pushing myself and it keeps sticking. i managed a new personal best driving through an absurd amount of traffic but still several seconds off my goal. i have a private event i may attend here in just over a week if weather holds out. oh and last event i never saw over 3bars on the cluster for coolant temps (running the aem series 1 and modify module) so that puts me under 190* at speed!
ninja edit: also finally got around to welding up my custom 3" single exhaust.
Nice build man. Maximizing performance at lowest cost possible. I like it!
thank you!
did take it out to a private track day with insane amounts of track time. I think there were about 20 people and open track for 5 hours. at the previous event I attended i snapped an axle on corner exit on my 1st hot lap on the last corner of my last session. I was bummed as predictive lap time was a new pb but luckily found someone with some spare part store axles. bought one of his spares, slapped it in and drove home defeated but at least driving. i noticed on the drive home i had a abs light, I assumed i nicked the sensor or something when i swapped the axle. ordered a used sensor and popped it in a day before the private event, didn't fix the light. was confused, check over everything, figured hell Im paid up for the event ill take it easy in brake zones and drive with no ABS, no biggie, right....wrong. apparently the abs sensors do more than just run the abs system, it also does some brake torque something or others. over 25% brake application it would lock up the inside front tire every time. luckily i was attending the event with a s2k buddy and asked he bring his spare axles with just in case i snap another as i knew i wasn't going to get another part store set in time. i just wanted to be prepared. after further investigation i noticed the abs ring gear wasn't aligned with the sensor, wtf, brand new axle was junk. swapped in one my buddy brought and boom back in business. unfortunately I lost a great deal of track time to fixing this. oh well, jumped out for 2 more laps and dropped 2 seconds off my PB, still la long ways away from where i want to be but steps in the right direction. alignment was definitely off, not enough rear camber, notice one front wheel had considerably more caster than the other to the point it was visible. off season plans consist of addressing the underside of the car, replace all the bushings and maybe check to see if i have a bend lower control arm up front as the adjusters seem like they are in similar locations but visually vastly different settings. the harder you push the car the more apparent the alignment being off becomes and looking at the data i was carrying less speed in the esses on 285s and more aero than i was on 255s, backing up my suspicions. so i have some great usable data to address the most important areas that need improvement. oh and set a new record, cracked a rotor in about 2 dozen laps lol, but gotta love those autozone lifetime rotors
Some small updates on the build. Covid pretty much messed up the entire season, mix into that a new baby boy time and funds have been limited. but digging in over the off season i found some issues that likely played into the handling of the car last year. either my driver side lca or knuckle was tweaked. i swapped those out and that corrected the alignment up front. i installed rear upper adjustable camber arms which gain camber by pulling the top of the tire in which made fitting the tires under the flare easier(and required by class rules). then did a fresh alignment. i spent a great deal of time trying to figure out a boost control issue, for whatever reason during a shift in race conditions the wastegate would flutter at a much lower boost level. i tried about everything you could think of. i contacted ap1chief (jm tuning) and had him dig in, while in there i just decided to have him retune the car completely. car feels amazing, he did a fantastic job and couldn't recommend him more. originally i installed a 7psi spring and 4 port controller to dial in some more advanced boost control but the 4port proved troublesome and inaccurate with changing weather conditions. so i moved to a 3port. i didnt however change out my wastegate spring so we were getting 20psi and it dropping off ontop likely to the spring not stong enough to stay shut. so ill be tossing the 11psi spring back in and hitting josh up to crank her up a bit more on kill. for now 440whp is more than plenty.
next area to address was brakes, i was cracking rotors way more than id like and missing sessions because of it, found a smoking deal on a set of wilwood 6 piston bbk so i jumped on it, paired it with the ballade 13" rear rotor upgrade to correct bias back to a manageable 106%f
and the last major change made was addressing rear aero, i knew i was pushing it with the amount of front aero i had and running the j's wing at max. it just wasnt going to cut it, i found a used crawford composite wing blade off an old IMSA gt3 cup car, 72" x 12"... this puppy will be more than i will ever need in street mod class trim. whipped up some chassis mounts that bolt to the trunk floor, made them 2 piece so i can unbolt the upper section and still get into the trunk and were good in this department. still need to do something about the endplates, not pictured but i did make the holes adjustable so i could level out the end plate.
i have more on my todo list and a pile of material to get onto the next projects, hidden bumper beam hitch, which then gives me the room for a diffuser. front tire blockers/spats and a few other small plans. i'll be headed to the track tomorrow for #gridlife midwest festival hoping to set some new personal bests and maybe achieve the times i set out to when i originally started the turbo build.
06-11-2019, 07:05 AM
