Front splitter and spoiler project

[Don L.]

Ok, it was a tough decision to start drilling into my Supras well maintained body, but it became apparent to me that to be more competitive in autocross, I would need some aero aids (at least that's what everyone was telling me). So, here I have my first versions of a front splitter, made of 1/4" Aluminite (an aluminum wall board material, honeycombed center, sandwiched), and the rear spoiler made of 1/4" abs plastic, 10" tall, limit of the rules. Still just testing for benefits now, will get around to painting the splitter black later, and possibly trimming the rear spoiler too. Maybe won't need all 10" height. Sorry for the ugliness. For now I'm looking for purposefull, later for pretty. Tested the car at autocross with just the front splitter, seemed to turn better, less understeer. Not dramatic, but noticeable. I'm hoping the rear spoiler will add some stability in high speed sweepers. Big thanks to Frank C. for idea/design of the front splitter. He used abs plastic for his, which I think is better for daily use, but mine is mostly autocross duty, and extends out to far edge of the bumper, so it won't see normal street usage. Can't wait for the next autox to try this out.

Don L.

http://i196.photobucket.com/albums/aa249/toy4speed_2007/supra%20pics/DSC_1402.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/supra%20pics/DSC_1400.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/supra%20pics/DSC_1399.jpg

[celica fanatic]

I'm loving the wheels. :)

[Malloy]

Cool! Love those steamrollers too ;)

[Don L.]

Thanks! They're awesome with the tires :)

[7mgt-66e]

Good thing they are functional, cause I would say, RICER! I've never seen anyone with this kind of mod. Let us know how it performs. I don't think I've seen the specs on your wheels? Post some info in the wheels section if you have not.

Is it still gonna be a street car? If so, I suggest keeping the parts off unless you're on the track.

[one2spooku]

Steam Rollers.

They do look pretty aggressive:thumbsup:

[Don L.]

Haha, call me a Ricer... at 53 y.o., all it means to me is dinner time :)

Yeah, the car is track only, but I've designed the splitter to come off with wing nuts, and the rear spoiler comes off with 3 screws. Car is street legal, and I will tune the motor on the streets, but would never drive on the streets with that stuff on. Heck, I'm not sure I can get outa my driveway with the front splitter.

Wheels are 15x10 Work Equip, -13mm offset, 275/35-15 Hoosier A6 tires.

Don L.

[SupraFiend]

Interesting, I'm curious how beneficial this will be. I've never felt I reached high enough speeds to worry much about aero, but our venues are usually pretty tight and I rarely get out of 2nd gear.

Not to get off topic but how has the car been with the new power from the itbs and SDS? You catching up to those pesky beemers yet?

[Sean Chung]

Those things look serious! They should definately help in the aero department. When's the next test date? I don't think candlestick is the best test site, maybe stockton. Hopefully I'll have my car running and tuned before the divisional. I would like to see how you mounted the spoiler. I had a similar idea with abs, but it was only about 3 inches high, then I chickened out and didn't want to drill holes in my hatch. Went with the little lip on the stock wing instead.

[Turbosidosis]

I think the splitter looks great! And i'm glad to hear that you can feel at least a little difference in a competitive environment. I did a splitter a few months ago, mainly because I was looking for a more agressive look. I hope to take more advantage of it when I get off the stock suspension. And of course those wheels you have are seriously bad ass.

http://i162.photobucket.com/albums/t261/Turbosidosis/86%20Supra%204-13-09/mk24-13-09-020.jpg
http://i162.photobucket.com/albums/t261/Turbosidosis/86%20Supra%204-13-09/mk24-13-09-018.jpg

[Atl_Racer]

Thanks! They're awesome with the tires :)

what size tires are those?

[sickntwstdtoy]

Wheels are 15x10 Work Equip, -13mm offset, 275/35-15 Hoosier A6 tires.

Don L.


theres your answer atlanta racer

don. i dig the splitter not sure i like the spoiler but if it gets you around the course in better time than by all means it's awesome because its done its job.

[Atl_Racer]

sorry, i missed that.

[Superium]

Wheels....Yes, splitter and spoiler....No thank you.

[Greg G]

Don is the man... rock on playa.

[Don L.]

[QUOTE=Turbosidosis;566179]I think the splitter looks great! And i'm glad to hear that you can feel at least a little difference in a competitive environment. I did a splitter a few months ago, mainly because I was looking for a more agressive look. I hope to take more advantage of it when I get off the stock suspension. And of course those wheels you have are seriously bad ass.

Gosh, everyone else's splitter looks soooo much better than mine! I really need to paint and detail up the front end. The splitter hangs about 4" above the ground, so I can clear large rocks, newspapers, maybe a coke can, but it's not everyday survival worthy. I really like the better "planted" effect on the front end in autox turns. We tend to overdrive the car in turns (resultant understeer), but the car seems more tolerant of aggressive corner entry now.

The rear spoiler is a whole different story. Visually, it's not my favorite either. Almost a Nascar appearance to me, but if it works (and I expect it will), then I will trim and shape it a little to help the look. I also am bothered by not being able to see behind me too well. The abs block half the view out the back. Might go to smoked plexiglass or acrylic to test.
The rear spoiler is attached to the hatch via 3 nutserts installed on the deck. Hated to drill, and bought a used hatch just to practice the install, then drilled mine.

As for the ITBs and SDS system, I'd say the car is at least competitive with the Nat. Champ E46 BMW in DSP. Specs on paper put us well behind, but the San Diego Tour this year had us within 1/2 sec in raw time on some laps. Pretty good for a hilly course. The car's success will hinge on the handling development, thus the aero aids. Frank's 6m with ITBs will easily have 25+ hp on me, so I can gauge my progress on his times too. I might squeeze
180 hp/190ft-lbs out of my engine, but not much more. The ITBs helped my torque more than I expected.

Frank, still got some stablilizer rods for the splitter? If the right length, I could use a few!

Don

[godzilla]

How does that spoiler affect the view out the back window? By the way nice do it yourself solutions for track use.

[Don L.]

How does that spoiler affect the view out the back window? By the way nice do it yourself solutions for track use.

Pretty much the bottom half of the rear view is gone. Unless you are being followed by a lifted 4x4, you might not know what's behind you. My options include lowering the height of the spoiler, or changing to a see-thru type material. One of the issues is that th rear spoiler has to bend slightly, going from side to side, can't be straight across. The rear of our hatches are slightly curved and I was trying to match that.

Anyway, at our speeds at autox turns of 35-45 mph, I'm expecting to get the rear end to stay more planted, since the tru-trac needs both rear tires to be on the ground to work well.
2 weeks till next autox, we'll see.

Don L.

[Tanya]

Can someone please explain to me what the splitter does, how it makes the car "turn better" ?

[85supra15]

I can't do it very well but this should tell you its all about pressure:

http://www.e30m3project.com/e30m3performance/myths/splitter/splitter.htm

[Don L.]

Hi Tanya, mostly it's mental. However, much of the autox game is mental, so it could be significant :)

Mostly, I believe that the splitter creates a downforce at the front of the car, at a given speed, thus increasing the grip of the front tires. Probably has no effect till at least 25 mph, and then some will contend that there is no benefit till much higher speeds. Certainly at track speeds there is a benefit. At autox speeds, where we seldom exceed 60 mph, the splitters and spoilers have to be rather large (and ugly) to have a small effect. Try sticking your hand out your window at 40 mph, then imagine a spoiler thats 5ft x 1ft sticking up in the windstream.

I have a fellow racer that during one autox removed his rear spoiler (similar to mine) from his BMW 325 because he felt it slowed his acceleration. It was a big course, fairly high speed, and the spoiler was clearly hurting more than helping that day. So, its once again, all about the tuning!

Don L.

[Don L.]

I think the splitter looks great! And i'm glad to hear that you can feel at least a little difference in a competitive environment. I did a splitter a few months ago, mainly because I was looking for a more agressive look. I hope to take more advantage of it when I get off the stock suspension. And of course those wheels you have are seriously bad ass.


Hey, I like your tow ring on the front of your car! How's it mounted and is it usable?
I could use a few of those!

Don L.

[xiong80s]

I'm loving the wheels. Definitely looks like an AutoX vehicle w/the rear spoiler added.

Turbosidosis tow hook seems to be made for a HOnda mounted on the factory tow hook?

[bshapton]

What's with all the beeeeautiful silver cars? Don't see many of those up here. Also I have to weep to see those mint hatches drilled! :sadsmilie I've had to deal with so many rusty (lightened for autoX?) hatches here .... oh my, so sad.

Bob

[hambone]

I thought the splitter reduces the amount of air going under the car causing less lift for the car in general. But hell, I don't know much.

[donkey2]

^^Kinda yes, not only takes the air and keeps it from going under, but it mainly redirects the air up instead of down and presses the front down(two fold) It depends on the size(obviously) as to when it takes effect it is possible to build a splitter effective at speeds below 25mph but they have to be huge(Pikes Peak Puegot 405). The one in the post #1 looks good for 25+(not certain without meausrements) They are a pain in the ass to tune. I wish you the best of luck, and don't forget to play with shape, angle, and side canards/diffirential angles to tune exactly where you want the downforce to be and when you want it to be effective.

[turbogoo1]

My heart sank when I saw that you cut into that beautiful hatch....but if it helps you out...good!

Save some rust free wingless hatches for the east coast!

[jrok]

but i think there is to much of an angle on the spoiler to help any, i think it will act as an air brake!!!!! just my thoughts

[theWeezL]

I remain unconvinced that those modifications are anything more than mental.

[Turbosidosis]

Yea, my tow hook is the standard Honda Civic rear one they sell on ebay. I mounted it to where the stock tow hook bolts in using another spacer piece of metel I made. It's on there pretty good and will deffinatly move the whole car if I had to winch it. My splitter goes up to the front tires like Don's and up to the oil pan covering the stock tow hooks. Also even if I didn't have a splitter and I tried to winch my car with those stock tow hooks the cable would most likely cut into or deform my bumper or cressida lip and my car is not even lowered yet.

[Don L.]

Autox results today with the splitter and spoiler are encouraging. Rear of car is definitely better planted with the rear spoiler. Our top speed with the spoiler was 3 mph more than without. (we ran 4 laps with and 3 laps without). There was a noticeable looseness in the rear w/o the spoiler. Seems to help in the slalom. I was concerned that too much drag might result from the rear spoiler, but it didn't show in the data. We use a Max Q Data gps system to collect data, video to review too. Now I feel that the front end needs tuning to grip better (relative to the rear), so some alignment changes may be in order. The aero stuff seems to necessitate new suspension settings. Here's a few pics.

http://i196.photobucket.com/albums/aa249/toy4speed_2007/supra%20pics/bmwautox1061409.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/supra%20pics/bmwautox3061409.jpg

Don L.

[Don L.]

Notice the high performance rear window decal :)

Don L.

[SupraFiend]

Cool! Will you remove the wing for lower speed events?

[BillyM]

See vid cam.... demand video.

--billyM

[Tanya]

Nice pics! But I think the stickers have increased your drag and are slowing you down :p

[Don L.]

Cool! Will you remove the wing for lower speed events?

After running this event with and without the wing, I think I'd rather leave it on all the time, and tune the susp accordingly. I can adjust shocks fairly quickly, but ride height and alignment settings take awhile. I'm surprised that the rear wing didn't seem to slow us down in the higher speed elements of the course. Perhaps Rusty's modeling could support that the wing results in less over drag. Wouldn't that be a kick?

One of the autox setup methods I may try is make the susp setting such that the rear of the car is very loose (rear toe out, stiff rear springs, stiffer shocks, higher rear ride height, some combo of such), this should help the car turn extremely well in th slower stuff, but be a handful in the faster stuff, but then the rear wing (spoiler in my verbage) would act to settle the car down in th faster stuff. So the spoiler would do little at low speeds, the car would sping like a top, at higher speeds the spoiler would plant the rear down such that we could keep looking forward.

I'm considering this method.

Don

[kmfdmk]

I thought the splitter reduces the amount of air going under the car causing less lift for the car in general. But hell, I don't know much.

Like donkey2 mentioneed, it prevents air front going under the car to a degree, creating a High Pressure zone over top the splitter, and also creates a Low Pressure zone UNDER the splitter pulling the front end down. Also hold up 2 loose sheets of paper parallel to each other (held vertically) about an inch or so apart and blow between them. You'll see that the air moving between them creates a low pressure zone, and the non-moving air on the outsides pushes them together. Think of one sheet of paper as the ground, and the other as the splitter.


but i think there is to much of an angle on the spoiler to help any, i think it will act as an air brake!!!!! just my thoughts

If Don was reaching faster speeds the wing would create more drag and offset the amount of downforce it creates. As it is the lower speeds that Auto-X participants see on a regular basis make this spoiler fine for most of the tracks that I've personally ever witnessed. Larger more open/higher speed tracks might necessitate swapping for a shorter spoiler height, or a slightly less agressive angle.


I remain unconvinced that those modifications are anything more than mental.

And you need to check out the 2D MKII Airflow testing that's linked in my sig and you'll see that Don has done pretty much was exactly needed. I suggest attending a local Auto-X even or track day and ask the drivers about splitters and wings and how they help.

Don.

I'm not too up to date on SCCA rules. How LONG (out front) can you make the front splitter. If you're looking for even more downforce up front I'd suggest lengthening the front air splitter. However as Donkey2 suggested look into adding stall fences (the flat plate of aluminum you see on wings that's on the left & right ends), also some canards or fences that aren't necessarily straight (when looking down from above) would affect handling as well.

A word of caution. Make sure that front air splitter is securely attached.

This air splitter for an e36 M3 BMW ...
http://i428.photobucket.com/albums/qq6/joe91985/airsplitterproject001.jpg

Has mounting brackets that are THIS beefy (stock!!)
http://i428.photobucket.com/albums/qq6/joe91985/iphonepics067.jpg

[Don L.]

Great info and feedback guys! Some of the higher speeds we were getting this weekend with the rear spoiler may also be due to higher exit speeds from the previous turns, the spoiler allowing us to put down the power on exit, getting us more speed by end of the straight. Hard to argue with the clock, and the results are pretty good. My son and I co-drove the Supra this weekend at the BMW autox. Our times were very good considering the Hoosiers were cording and show metal by end of the day, but his times were still near top time of day. Better tires and the car would have turned in better, and it would have been more fun! Here is the link to u-tube one of my runs, the other 3 videos are his runs. I think he drives more aggressively :)

Enjoy his videos, lots of videos from our STI running Street Mod class too. You won't confusse those with the Supra :)

Turn up the volume, the sound is kinda weak.

Don L.

http://www.youtube.com/watch?v=CsZLNESSt5s&feature=channel_page

[SupraFiend]

Great vids! Nice to see some from an experienced driver and a nationally competitive car on here. I'll have to browse through more of them sometime.

And awww man you guys have a nice venue, and a nice cone budget too!! I'd love to do an autox at a place like that. Our current pad was just paved and its nice but its a little on the small side. We'll see if it gets doubled like originally planned. The neighbhors have been complaining and we almost lost the venue for good.

[Malloy]

Don, your car is bad to the bone.

[Don L.]

Update for an old thread. Wanted to add some pics to this thread since some questions have been asked about attachment methods. I used the flat metal channel that often seen used in supporting a garage door opener. Has holes already, pretty easy to cut and bend into 2" tall "C" brackets for mounting the aluminite splitter material. I made these "C" brackets to attach below the factory front lower lip. Frank C. gave me much of the ideas and his black abs splitter still looks like one of the best. My rear spoiler has been changed to a clear plexiglass material. I like the see though feature better than my original black abs design. Still works well, not as fugly as my original design. For next autox season, I will be redesigning the front splitter to extend approx 6" forward of the bumper. Current DSP class limit forward protrusion to edge of bumper, but next year I'm going to Street Modified class which has diff rules. My rear spoiler may be replaced with a full adjustable wing. That should get me more "ricer" comments :)

Here's some pics of the "C" brackets and the 2 "L" brackets on the factory tow hooks. I welded 1/4" bolts onto the brackets so when I put the splitter up against the brackets, I used wingnuts (yes, wingnuts) to hold the splitter in place. Wingnuts make for quick removal, and easy tightening. Clearance not a problem.
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0116.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0117.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0118.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0119.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0120.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0124.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0125.jpg

Then a strip of abs to cover the gap between the stock front lip and the top of the splitter. Held in place by some 1/4" screws and nuts going through the brackets.
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0121.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0122.jpg

The aluminite panel cut to fit the contour/shape of the bumper per my autox class rules. My next version will extend more forward, and have a rubber molding along the front edge.
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0123.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0126.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/DSC_0127.jpg

The front supports are just threaded rod (stainless) bought at the hardware store, with small rod ends on each end, attaching the under side of bumper to an "L" bracket on the splitter. Autox speeds aren't usually over 70mph, but I felt these 2 supports were needed, especially if I mangle some cones. If I were road racing, or going faster, would probably have at least 4 supports.

Below are two pics from our visit to Wendover, Utah for a Nat. Tour. You can see the rear clear plexiglass is much more subtle.
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/wendovertour32010.jpg
http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/wendovertour52010.jpg

Enjoy the pics, I will try to update the thread when I redesign the splitter and rear spoiler for 2012. Have to work on the new engine first :)

Don L.

[Don L.]

I realized the smaller pics don't show the rear spoiler well, here's a bigger pic, hope its ok.

http://i196.photobucket.com/albums/aa249/toy4speed_2007/pics%20to%20share%20supra/supra%20splitter%20and%20spoiler/wendovertour52010-1.jpg

[Suprajayaz]

As always - great work and that's an excellent photo!

[SupraFiend]

Yep, another calendar hopefull there I would say.

[Don L.]

Nah, maybe sometime next year will get a high quality race pic. I've been fortunate enough to have been in the calendar previously, I'll stand back for a while. Just hope to get that 1jz motor ready for next season. Seamus, one of my main goals for next season is to bring the Supra up to Packwood to run against those Nissans (Don Nimi, etc). Nice guy, met him at Nats. If the Supra is competitive, I'll be there! Hoping Street Mod grows a bit this year. Seemed like many cars left, but a nice variety of cars slowly coming into the class too.

Don L.

[SupraFiend]

Cool, just let me know in advance and I will be sure to come down and race with you.

Don Nimi is bloody fast. He's my benchmark up here for the level I need to get my car to to be capable of FTD. A looong ways to go still.

I don't know, that one with the plane is a pretty nice shot. Would be good variety for the calendar.

[SupraLee]

Awesome install details! I'm planning on fabricating a front splitter as well. Had a crazy idea to try and adapt the AE86 TRD spoiler to my hatch.

[killbill oddy]

Awesome install details! I'm planning on fabricating a front splitter as well. Had a crazy idea to try and adapt the AE86 TRD spoiler to my hatch.

Dunno where you would get such a crazy idea from:ugh::laugh: i've updated on driftworks btw ;)

http://i106.photobucket.com/albums/m260/spoon_4130/FILE0015-2-1.jpg

http://i106.photobucket.com/albums/m260/spoon_4130/FILE0016-3-2.jpg

Hey im having one piece frp rear bootlids made soon with the spoiler integrated into it, will be very light but strong enough to use daily.

As for splitters and spoilers, i did notice an increase in downforce when i had my volvo lip spoiler on the front, but only about 85-90mph. Needs to be pretty flat under the car to have ground effect.


@Don L, Glad the rear spoiler works good, but it kinda ruins the nice work you put into the car with those awesome wheels:sadsmilie
Maybe a rocket bunny rear spoiler will be more up your street? Lots of angle and drag, just more honed product.
http://www.ebay.co.uk/itm/NISSAN-180SX-200SX-ROCKET-BUNNY-DUCK-TAIL-REAR-SPOILER-/360325888446

[Don L.]

Hey Killbill, I like that AE86 rear spoiler job! Pretty clean! Yeah, I hated to drill and tack on my rear spoiler 'cuz my car is an original owner in very good condition, but for my autox goals, it was needed from a technical aspect. At least I know the rear spoiler has a positive effect at autox speeds. I wouldn't use it at road race speeds, it would be crazy to have that much downforce at 100+ mph, plus it would need reinforcement. I still plan to go rear wing in th future. More ugly, posibly more tuneable, crazy. For the front splitter, I just plan to use my same basic design, just build stronger brackets, make it easier to install/remove, and make it bigger. Should be able to have breakfast on the front lip :)

Have a good day!

Don L.

[SupraLee]

Haha, totally had the idea and then searched and found your thread on it, awesome job on adaption. But I'm kind of digging the rocket bunny rear spoiler you showed Don

[Sam_Smiles]

I love the setup Don. Low, ITBs, splitter, fat tires, and a tall wing is a textbook autocross setup. You know, when in rome.. watch the fast guys. LOL. Anybody who questions these mods definatly hasn't gone autocrossing. Those cones come up faster in real life, than what's shown in videos. Aero especially helps in a sport where grip is key.

Definatly let me know if you're planning on heading to the PNW for any events (Nats or Regional). I've love to race/chat with you and Fiendy sometime. I'd especially love to compare times. Muahahahaha!!

BTW.. I'm thinking about heading down there next year for a Hooked on Driving (http://www.hookedondriving.com/hooked-on-driving-events) Event.. I'm thinking Laguna Seca!! I'm going to do a post on the HOD in the racing section to try to get more MKIIs out there on the track.

[Don L.]

Hey Sam, your 1jz thread is one of my most studied links! I'm almost ready to start my 1jz project, really hoping to have the car autox ready by next February. Thankfully, your 1jz info and that of a bunch of others have kept me up late at night reading. My eyes get kinda sore after 15-20 pages of monitor reading!

Yeah, would love to come up to Packwood next year. One of my main goals for the car!

Don L.

[SupraLee]

Hey Don, where did you get the aluminite panel and how did you cut it so neatly?

[Don L.]

I got my 4x10 panel at a wall paneling factory a few towns away. I'd have to find my old receipt to get the name of the company. I believe this are wall panels, available in 4x8', 4x10', maybe larger. With a 4x10' piece, I could may 4 pieces of 2x5', which is the about the dimensions of my front splitter. I recall the 4x10 cost about $200. Its about 1/4" thick. Use a metal blade in a circular saw to cut the straights, and a jig saw with fine metal blade for the curves. The metal cutting circular saw shoots metal everywhere, kinda messy, but quick.

Don L.