posted on January 13, 2012 00:00
Project S2000 - More Winter Testing and a Challenge
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.
It started off like any other chat conversation (note: actual words may have been modified from the original text in order to fit the screen and time allotment)
Khiem: Yo Martin, what's happenin man?
Martin: Workin. What's up with you?
Khiem: I need to take the S2k out for a track day in cold weather.
Martin: Oh yeah? I need to take the SE-R out. Speed Trial USA has a day coming up at Streets.
Khiem: Perfect! How much power does that SE-R make...
And so the bench racing began. Let me back up a bit first as to the reason I needed a track day. Last winter, I did a day at Streets of Willow running the counter clockwise configuration. Since then, I have revised the suspension and added the oiler cooler, so I wanted to see how the car handled and how well the oil cooler performed in similar conditions and on the same track. Martin has a B13 Classic SE-R that needed the cobwebs shaken off. Let's see how they match up shall we?
In corner #1, we have Project S2000. Weighing in at 2950 pounds with the driver and packing about 200whp at the rear tires. Project S2000 rolls on 245 wide Bridgestone Potenza RE-11s tires with 20,000 miles of usage and a lot of track time. In corner #2 sits Martin's B13 SE-R. This is no ordinary SE-R though as a SR20VE resides in the engine bay generating about 200whp to the front tires and weighing in around 2825 pounds with driver. The SE-R can comfortably fit 205 width tires.
|S2k vs. SE-R. The battleground was Streets of Willow at a track day put on by Speed Trial USA. Thanks to Maddog Mike for putting on a fun and laid back track day! Also, a quick shout out to a few MotoIQ readers we met at the track.
The power to weight ratio is decidedly in the favor of the SE-R with each horsepower only needing to lug around 14.125 pounds. The S2000 has an extra 0.625 pounds to carry per horsepower putting the S2000 at roughly a 4.5% disadvantage. The advantage in grip however goes to the S2000 with a weight to tire width ratio of 3.01 (2950 pounds divided by 4 x 245 width tires). The SE-R has to support 3.45 pounds per mm of tread width in comparison. That actually gets worse if you look at the situation more accurately and examine each end of the vehicle individually as the SE-R has an approximate 60/40 weight distribution. 60% x 2825 = 1695 pounds on the front pair of tires. So that means the front tires need to carry around about 4.13 pounds per mm putting the SE-R at a whopping 37% disadvantage in front end cornering grip.
*Is there already an established performance parameter for tire width to weight in common use? If not, maybe I should claim it; if Coleman can have his Monkey Power Point, I can have Khiem's Grip Ratio (or some other name…. Traction Ratio? Loaded Rubber Ratio?)
In a straight-up street tire battle, it appeared the S2000 easily had enough of a grip and handling advantage to overcome the power deficit on the relatively tight Streets of Willow road course. However, Martin had a card up his sleeve to level out the playing field; Martin brought along an old and well-used set of Toyo RA1 track tires to add grip to his setup. In order to try to balance the understeer experienced by his street driven FWD set up, Martin stuffed 225 wide RA1s in the front while using 205s in the rear. This should allow the car to rotate better, while reducing the weight on the front tires to 3.76 pounds per mm of width. So now the battle consisted of worn-out sticky street tire RE-11s vs. worn-out sticky track tire RA1s. This was shaping up to be a very close battle.
|Not towing to the track requires stuffing lots of gear in your car. "Hey Khiem, bring your jack and jack stands. I'll bring the tools and chairs!" Here's Martin swapping on the wider track rubber and front brake pads using my jack and jack stands that I was able to stuff in the back of the S2K.
The forecast for the day was a low in the 20Fs and high around mid-50Fs. Considering the reduction of oil temperatures from the oil cooler, I decided to stick with the standard 10w-30 fill instead of the thicker 15w-50 I had used for previous track days. I was feeling especially lazy and decided to forego my ghetto cooling ducts too.
The drive in the morning to the track was COLD. The air temp was only 22F with my oil only reaching 60C (140F) despite the Mocal thermostat being rated for 170F. I am glad I decided to stick with the standard 10w-30! This also proved to be a good decision with my peak oil temperature for the day only hitting 108C (226F) with ambient air temperatures around 55F. 108C is a little warm, but well within reason as the car was designed to operate with an oil temperature of 100C in constant highway driving in warm weather. In going up a mountain grade when the car was stock, I'd gotten the oil temperature up to 106C. So the oil temperatures and pressures were a non-issue with the standard 10w-30 during tracking in the cold weather with the oil cooler. The oil temperature readings are courtesy of the ARK Design MFD-II of course.
Friday, January 13, 2012 4:17 AM
Khiem great reading. Thanks for sharing.
Try to stuff 255 tires all around (either Dunlop Direzza Z1 Star Spec, or Hankook Ventus R-s3), you might be able to pick up 1-2 seconds.
Upgrade the rear stock calipers/ rotors with the Stop-Tech ST40 and get rid of the parking brake (the S2000 project is officially retired from the street :P).
.....and please, do me a favor, don't turbocharge/ supercharge it. Keep it NA.
Friday, January 13, 2012 4:30 AM
Could You give a few more details on that neoprene Ducting or where it is fixated on the other side?
donno why but cant wait for that article of the ducting made permanent :D
Friday, January 13, 2012 11:40 AM
@JDM, while the car is no longer the DD, I still drive it once a week. So it still needs the parking brake. I had tossed around the idea of getting the rear StopTechs and making a custom extra caliper parking brake setup, but then I’d still need spacers too to get wheel to caliper clearance (I think). I also thought about the Racing Brake setup that uses a larger rear rotor setup, but that would throw off the brake bias. I’m very happy with the current performance of the braking setup, but the rears just need more cooling, so the cheapest option is to do some ducting. That frees up time and money for other mods with more worthwhile gains.
As for tires, I hate the Star Specs. I had them on my Evo directly after running Potenza RE-01Rs. While their ultimate grip was similar to the Potenzas, their feel was completely different. They did not inspire confidence and felt like the threads were chunking; not a good feeling when swinging through turn 1 at Streets of Willow at about 95 mph.
I also can’t go wider than 245, and the Star Specs run wider than the RE-11s too. I pulled out the shock and did a fender clearance check a long time ago. At full compression with the 245 RE-11s, they JUST touch the inner fender linear. I bent up the tabs about 45 degrees to give a smidge more clearance.
The Hankooks have more ultimate grip for sure. Apparently, their sidewalls are a bit softer and based on some testing a friend did between RE-11s and RS3s, the RS3s need another 0.5 degrees of negative camber. I am considering them though as while they don’t last as long as the RE-11s, I don’t need them to last long anymore with the little mileage I’m now putting on the car.
And the car will stay NA. Sorry DaGou, boost is no longer in the plans.
Friday, January 13, 2012 12:58 PM
I still think that someone needs to come up with a standardized measurement for tire grip. Then you could make a better comparison between the tires you're running. But mostly, it would help those looking for the right tires.
I still don't know why no one seems to use fiberglass for brake ducts or belly pans. Is there a reason? It's cheap, can be made into any form, and can be shielded from extreme heat. What's the issue.
Also, I think the Khiem Ratio sounds great. Better than the Dave Point ;) (kidding. Dave is awesome)
Friday, January 13, 2012 2:45 PM
@jeff - Part of the reason that brake cuts aren't fibreglass is that it's easy to get NACA ducts made out of durable plastics for cheap. all you need is a big pair of scissors, a littl epoxy, and some bolts and you can make those ducts work almost anywhere.
Another big reason is that brake ducts and belly pans constantly get whacked by debris, kerbing, and (sometimes) other cars. It can get pretty tiring remolding new brake ducts every couple races. I would consider using fibreglass for a splitter, but only as a wrap to surround a plywood core.
Monday, January 16, 2012 9:49 PM
I want to try playwood shot with bedliner materail for a splitter. The miltary uses bedliner to help Humvees resist IUD's so it might help a splitter resist splintering.
Tuesday, January 17, 2012 10:14 PM
spdracerut, thanks for remembering I am a S2000 Turbo Fan. I can't beleive an application design engineer who eats sleeps and poops turbos would not want to design and apply the absolute most perfect turbo application for his car!?!?!?!?! Maybe you are just sick of turbo this turbo that all day long? If me and the rest of the turbo fans can't twist your arm and you do go NA (boring) you still have to design the perfect setup for everyone else! You probably already have it on paper.
On another note still think you need to do something with the back brakes. I will present my case in a later post, stay tuned but do not hold your breath, thanks.
Go with K.A.T.R. pronounced kay-ter for Khiem's Automotive Traction Ratio.
Tuesday, January 24, 2012 8:49 PM
Khiem, I was rereading the whole S2000 series again. A lot has changed for you in 2 years. Back then you stated:
Our goals for Project S2K are not as crazy as the usual MotoIQ fare. We are not out to build the baddest assed time attack car or build an unbalanced street terror. With project S2K, we are going for refined daily driver performance. We want to get the most from our S2000 but we do not want to give up OEM levels of drivability. We want something that we can drive to work every day, then drive to the track without a trailer, pound out some fast laps and drive home. We also don’t want something that screams give me a ticket to our local law enforcement agencies.
The big change is that car is no longer your daily driver. So are your goals still the same after two years? Even though everything was well planned would you do anything different? Happy with the 245's, need the added traction of 255's, 18" wheels for bigger big brakes? And as you know I hope you use your vast knowledge of turbo charging application engineering and not go NA. Really, an intake, an exhaust, new throttle body, intake manifold, and for what 50 HP. Rather see some cool small twin scroll super responsive turbo application. Anyway the big question is are you happy with everything and what are the new goals.
Wednesday, January 25, 2012 12:53 AM
There's only one thing I'm going to revise and that's the front wheel spacers. The proper way to do it is to install longer wheel studs instead of the bolt-on spacer thing I used. The downside to installing longer studs is basically having to get new wheel bearings at the same time. Before, the KICS spacer allowed me to do what I needed to do easily and quickly. Now that I can put the car up on jack stands and not worry about having to drive to work the next day, I can do it the proper way.
Now that it's more of a fun car and not a DD, I'm going to tolerate a bit more NVH and noise. The motor mounts are shot so I'm thinking of putting in something a little stiffer. Maybe a mix of new stock mounts with one or two stiffer ones. I'm also thinking about intake, header and exhaust. A BIG maybe on the exhaust as I still want the car quiet. The intake will only be louder than stock when at WOT and the header won't add any more noticeable noise.
Additional safety items have already been planned. Overall, the car will become more driver focused, but still not extreme. It must still be streetable. Basically, think GT3RS, Z06, Cayman R, etc.
If the car were just for street duty, I'd turbo it in a heartbeat. But to make a car dead nuts reliable on the track for hours at a time is difficult at stock power levels and very difficult at double power levels. A turbo for sure would require track pads, even more oil cooling, and then you really have to start worrying about breaking the tranny and rear diff. Tranny and diff coolers would be good ideas too.
As the car sits, it's basically all the good stuff about the car amplified and it's actually a more comfortable DD due to the added chassis stiffness (no roof latch rattle) and better suspension. There are two major racing events I want to enter in the next year and a half, so that'll require some safety additions. Lots of small stuff to consider too as the stock parts wear out, like the rear diff mounts and control arm bushings. As they wear out, might as well upgrade.
Wednesday, January 25, 2012 1:39 PM
I have the upmost respect for you but Project S2000 is now about as exciting as Project Trailer...You do not want to build the car cuz it might break???? You want a track car to be dead nuts reliable??? Surprized you did not mention you wanted to get 40 miles to the gallon too. I guess I wish you did project S2000 10 or 15 years ago before you go to mature.
Wednesday, January 25, 2012 3:08 PM
@DaGou - I've never driven a Porsche GT3 but I have driven a z06 and can totally understand the desire to build a powerful N/A track car. Always better to be racing than sitting in the pits with a busted car and have to drag it home on a trailer. To that point, it's always awesome to take a car to the track, race it all day and then drive it home. It's pretty nice when your car is setup to do all those things. The crazy exotic turbo stuff is fun also but when your at the limit parts break which gets expensive. Looks like Khiem prefers to keep racing all day. All that seat time seems like a pretty good idea to me.
Wednesday, January 25, 2012 6:33 PM
I am sure where ever you take it will be well done and I will continue to learn from you. Thanks for what you have done so far, you have taken me done a solid well thought out path. The project is tight, reliable and sticks to the road like glue, what more could you ask for.
Thursday, January 26, 2012 12:15 AM
It would be more fun with a lot more power, but a conservative cost estimate to build a turbo the right along with the beefed up drivetrain is around $20k. More oil cooling, tranny and diff coolers, beefed up rear diff, stiffer mounts/bushings everywhere, lots of engine bay venting, making a bigger front opening to get more air into the engine bay/coolers, etc etc. One big issue is the smallish front opening on the S2k. Check out the front end of an Evo and it has a big opening just for the intercooler and then additional openings above that. A GTR has about double the front open area. More power = more heat to reject. So double the power = double the heat to reject. If someone wants to give me $20k :)
Monday, January 30, 2012 2:06 PM
Your automtive tunning knowledge dwarfs mine so much so that I am not even remotely qualified to disagree with anything you say. What you have said is that shelling out the five thousand or so for an average aftermarket kit for a turbo you need to put in another 15 thousand in parts to make the car worthy to carry the power. And even then cooling is an issue. All those companies out there making turbo and supercharges for the S2000 are just preying on a totally ignorant public. And those thousands of people who have boosted are riding time bombs(since few of them do the job right). I guess if I want a car that I can stay even with a run of the mill 5.0 Mustang I need to ditch this totally inadequate platform and find something else.
Monday, January 30, 2012 2:19 PM
DaGou, the platform is still really good. If you want to keep up with a 5.0 on the street, it doesn't take much. If you want to beat on the S2k on the track all day long and not break stuff all the time, you'll have to spend the money reinforcing all the complementary systems along with the engine. The same goes for any street car honestly. There are very few street cars (especially in the S2k's price range) that will hold up well to constant track abuse, Mustang included. They all need some track prep if you're going to race them on a road course all the time.
Wednesday, February 01, 2012 11:47 AM
An intake and exhuast system will not get the job done. What will it take?
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