Project S2000 - Track Testing Revised KW Clubsports and Earl’s Oil Cooler

By Khiem Dinh

Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing.  All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.

The last track outing for the S2000 showed a few deficiencies still existed in the setup.  The most problematic from a reliability standpoint was the scorching oil temperature.  From a speed standpoint, the car was still very loose (last track update).  Going back to the beginning of the project, you'll remember that we switched the tire sizing from a stock staggered setup (215 widths up front, 245 on the rear) to an even, or non-staggered, setup utilizing 245 width tires front and rear (Part I).

Acura were the first to pioneer this setup in modern Prototype racing on their car raced in the American LeMans Series.  Audi and Peugeot have since followed suit running tires that are basically even width front and rear on the R18 (360f/370r) and 908 (370f/370r) prototypes respectively.  In anticipation of the increased front grip with the wider front tires on the S2000, we added a stiffer Whiteline front sway bar and removed the rear bar (Part II).  As I've learned the car over time and started pushing harder and harder (my previous cars were FWD and AWD), I hit the limit of grip and determined I needed more setup adjustment to address the oversteer tendencies.

The next logical components to change were the front springs.  The KW Clubsports were designed for a stock S2000 using standard tire sizing, not for cars running a non-staggered setup.  After researching what many other track-only S2000s were running for spring rates, I decided to increase the original KW Clubsports spring rate of 100N/mm to 120N/mm.  Yeah, KW does it a little different and rates springs as N/mm instead of Kg/mm.  If you want to get super geeky, I guess it should be Kgf/mm which is kilogram-force/mm because a kilogram is a unit of mass on its own and you need to multiply it by gravity to make it a force.  So a Kgf implies a kilogram of mass multiplied by the acceleration of gravity to give you a force.  It's good ole F = ma.  1 Newton = 1 kilogram x 9.81 m/s^2 (acceleration due to gravity on earth).  So KW is technically more correct by rating its springs in N/mm.  Anyways, back on topic.

To test the setup changes for the Earl's oil cooler (Part IX, or 9 for those of you that don't do roman numerals) and suspension, I hit up another Speed Ventures auto-x and an Industry Track Day put on by the guys at Mackin Industries (Edward Lee is da man!); Industry Track Day is open only to those somehow related to the automotive industry, so it's a fun day with your peers. 

Earl's oil cooler Koyo Ano-tuff
Earl's Temp-A-Cure oil cooler with Ano-Tuff fittings and Pro-Lite 350 hoses.

On the drive to the auto-x, I was able to get my first real evaluation of the oil cooler.  On the highway with an ambient temperature of about 70F, the oil temperature would hover in the 72C-75C range which is approximately 162F-167F.  The Mocal thermostat was rated at 180F, so it's just about right.  The temperature is cooler than I would actually like it, but that was the only temperature thermostat available from Mocal in the sandwich adapter design.(EDIT: it turns out Mocal has one at 200F and it is a special order item.  I wish I had known this before as I would have gone for the 200F one)  On the stock setup, the oil temperature was about 90C/194F, so the oil cooler created a significant temperature drop.  With an ambient air temperature of about 85F and cruising with A/C on the highway, the stock setup would result in an oil temperature of 100C.  The new oil cooler setup reduced the temperature down to 85C.  One other little change was the coolant temperature.  It use to hover at 89C-90C, and now it’s a bit cooler at 87C-88C.  This is not a surprise as hot oil is no longer adding heat to the coolant system as was the case with the stock oil/coolant heat exchanger donut.

During the auto-x, I got to test out the other feature of my oil cooler setup which is the built-in oil cooler fan.  After each run, the oil temperature would peak at about 95C.  While waiting in the staging lanes for my next run, I turned on the A/C in order to turn on the fan mounted to the oil cooler.  With the fan running, it dropped the oil temperature down to 85C after a few minutes in the staging lanes.  So it worked just like I thought it would.

The last concern with the oil cooler setup was the resulting oil pressure due to the pressure losses incurred by the extra plumbing and oil cooler core.  I’m happy to report that the oil pressure barely changed.  At idle with an oil temperature of 90C, the oil pressure went from ~1.6 bar to ~1.5 bar, or a reduction of ~6%-7%.  At cruising speeds, the oil pressure remained around 6 bar.  The oil pressure reading fluctuates a lot at cruising speed on my sensor setup, so there’s no definitive number, but it seems to have dropped only a couple tenths of a bar out of about 6 bar of total pressure.  The conclusion is my oil cooler setup has an insignificant oil pressure drop.

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Monday, October 03, 2011 12:03 AM
Great reading Khiem.
Have you checked Robert Walker blog? (great tips for S2000 junkies):
www.maxrev.net (you might find useful information about spring rates and suspension setup).
As far as the rear brakes heating problem. Have you thought about removing the heat-shield and install silicon-ducts like you did in the front?
How about a Stop Tech rear BBK :)
Dusty Duster
Dusty Dusterlink
Monday, October 03, 2011 2:57 AM
How well do those KW Clubsports do for daily driving? I'm torn between the Variant 3s and the Clubsports...
Der Bruce
Der Brucelink
Monday, October 03, 2011 12:18 PM
Khiem - Some people are obsessed with the building of project cars but I love to see payoffs like this! It's nice to see your mods paying off as hoped. Your front rear brake wear and temp difference has got me intrigued and excited to see your final solution and results. Good stuff man, I'm looking forward to what's ahead!
Monday, October 03, 2011 4:15 PM
Maybe a stupid question, and maybe to the wrong people, but you all being so close to KW you might know. If one was to follow the project car, and have 245s all around will KW sell the perferred set up? Them seem to sell the "kit" with no options.
Monday, October 03, 2011 4:31 PM
Man-O-Man, if you do anything more???? What a tease!!! The car is so tight now you have to keep going and give us more power!!! You owe to yourself! YOu owe to your readers! Show us how to do a turbo right. Not over the top, keep it real, keep it on the street but ready to rock a few laps! Do what you do man......
Tuesday, October 04, 2011 10:22 AM
@JDM, I researched Walker's blog before I started this project. I also researched the Sport Compact Car S2k suspension shootout. I also researched a few other outlets. Unfortunately, 2 years ago(!) when I was planning out this project, there weren't a lot of heavily tracked S2ks. I'd say in the past year, the information available has gotten much better on the forums. Rob Robinette has a great site too (http://robrobinette.com/S2000TrackEvolv.htm).

Deep down, I knew I'd probably need an adjustment. All the other S2k guys back in the day were able to get away with the standard spring rates because they ran big ass rear wings in addition to a super stiff front sway bar. It's a bit of a bandaid in my opinion as I think the car should be mechanically balanced and downforced added evenly front and rear. So now I have the car mechanically balanced to how I like it. The more recent track junkies have also figured out they need to run staggered spring rates with the non-staggered tire setup.

For the rear brakes, I have two ideas in mind for directing air towards them. I'd love to do the StopTechs on the rear too, but I'd loose the parking brake. There are too many big hills around here to not have the parking brake!

@Dusty, even with the stiffer front springs on the Clubsports, I don't think they ride worse than stock. The car still rides better than my old stock 2005 Evo. Depending on what your ultimate goal is with the car with regards to usage will determine if you want the V3s or Clubsports. To take advantage of the Clubsports, you really need the stickest street tires you can buy. The compromise there of course is cost and tire life. The V3s are probably better suited if the car will see more street use. So I think it really comes down to your tire budget and not ride quality.
Tuesday, October 04, 2011 11:02 AM
More power? How ab the Rotrex supercharger kit? All I've read ab the rotrex on the s2k is glowing reviews.

I like how your build has progressed and it's cool that you hit your initial goals. Good to see a project car hit a milestone!

Does your one of your rear brake cooling solutions include a wide body kit? Or more ghetto ducting? :)
Tuesday, October 04, 2011 11:23 AM
Wilwood makes a parking brake. Some time in SolidWorks, and a visit to your local machine shop could yield a bracket to make things work... ;-p
Tuesday, October 04, 2011 1:08 PM
as for hp even basic hondata tuning will yield quite a bit and your car will still pass smog - or you can add a v2 intake, hytech header sport cat and I would say a custom exhaust most store bought is freakishly loud and produce 40+ more than you have now with tuning. If that's not enough or in lieu of that pick up a set of kia 4.4 gears. I went to 4.7's in my ap1 and it was the best single thing I have done besides strip out alot of weight.

Also tires in ALMS or sizes have no bearing - Acura "was" using a square setup because all race slicks "were" the same. There tire provider has now produced a tire intending to be on the steering end and as a result they have gone back to a staggered size to improve turn in, reduce drag and increase ride quality.

If your in the market for new tires I suggest the conti DW's I love all of the sets I've had and they are always rated very high and have good tread life.
Tuesday, October 04, 2011 8:17 PM
Not planning on any NA mods, namely intake or headers. The $:hp ratio is very poor. Not to mention, I like the car nice and quiet; I put on around 12k miles last year, so I rack up a fair amount of miles in this thing. I'm already partially deaf from my old Nissan with a 3" exhaust. Plus, attracting attention to a modified car in LA is a BAD idea.

No 4.4 or 4.7 gears either. I actually want 3.10..... but I guess I'll have to settle with 3.90 unless I can find another option. I'm trying to lower the highway cruising revs as much as possible to bump up the gas mileage on the highway. If I follow thru on the power plans, it'll have much more torque :)
Eric Hsu
Eric Hsulink
Thursday, October 06, 2011 9:03 AM
By "cosworth corners" do you mean Fujita Circuit? If you come on the weekends, there are drag guy practicing launches, drifters practicing drifting, and guys like me doing detailed driveability ECU work.
Thursday, October 06, 2011 5:10 PM
Ha you have plan for more power!!! Soooooo what's the plan? Hmmmm more torque, sounds like a 2.4 stroker from Inline Pro or a small turbo. With your emisson concerns it must be the stroker??? Do we have to beg for the plan???
Friday, October 07, 2011 7:37 AM

Have you given any consideration to this:

Friday, October 07, 2011 8:40 PM
@DaGou, I've always had a plan, it's just limited by money (and my lack of) :) For emissions, here in Cali, modern cars get plugged into the smog computer that reads the ECU thru the OBD port. I think that data is recorded in some master DMV database. So that has to work with no error codes present. Then there's the sniffer test on the dyno where they test you at idle and ~2500rpm under load on the dyno. So I think that data is also recorded and stored. As those pieces of data are stored in some electronics database, the car must pass those. The other check is the visual check which is of course by a human....

@epadilla19, I'm aware of the iVtec conversion, but that's more into the engine than I'd want to get. Reliability is a key goal and the OEM engineers spend a lot of time consideirng all factors like vibrations, resonances, bearing loading, etc. So I don't like messing around with stuff like that so much where I don't have a good understanding of how the changes may affect reliability.
Sunday, October 09, 2011 4:15 PM
So you definity have a plan for more that will pass CA emissions testing...What is it going to take for you to leak the plan?
Wednesday, October 12, 2011 2:30 PM
The ivtec kit is over priced garbage not suitable for anything more than race use if that. It's more cost effective at this point to sell your stock motor and pick up a k20/24 hybrid to swap in and run to 8k.

The author obviously plans for smog legal and tq - only boost is an option in CA for that. Supercharged boost most likely.

Let me just warn you before hand - based on your current set up you will hate it and I will be seeing your car for sale within the next year as a result. If you still plan to drive it anyway.
Wednesday, October 12, 2011 6:38 PM
@circuitsports, why do you think I'll hate it? This wouldn't be my first rodeo of putting a turbo on a non-turbo car. I've actually done three cars previously. My first, my old Nissan SE-R, I put on over 80k miles with the turbo on it (160k total) before I sold it.

I'm not going to do anything that I feel overly compromises the car. If Kojima had his way, it'd already have cams, header,loud intake and a loud exhaust. You'll just have to trust me :)
Monday, October 17, 2011 6:57 PM
I would say that was a leak! Looking foward to you releasing the plan in your own time. InLine Pro does sound like something that fits your constraints. Do it at home, still drivable, AC still functions, boost at 2500RPM. What is not to like?
Monday, October 17, 2011 9:01 PM
What's not to like? Simple, I can do better :)
Tuesday, October 18, 2011 5:55 AM
This is going to be good! Kits are for the masses, and in lots of cases the masses, sorry to say, ain't too smart, so the kits have to be dumbed down a bit. It will be more than enjoyable to see you apply all you know to doing what you are going to the S2000. If I did not already have one, I would go out and buy one! What you have done so far is such a great blueprint. Just hope you have the money to continue!
Tuesday, October 18, 2011 7:34 AM
Sadly, smog legal and custom turbo setup don't mix. How's that going to work out? Or are you going to ignore the 'inspection' aspect of the smog test and just ensure the exhaust gas is properly cleaned?
Tuesday, October 18, 2011 1:19 PM
@speedball, the best I can do is make sure it passes the OBD-II check and the sniffer as those are both recorded in the computer database. I'm keeping the stock cat for sure and maybe even the stock exhaust. All emissions components will remain intact, such as the air pump, PCV, etc. I like clean air, what can I say? There's no computer check for the visual inspection though.
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