Spec.B Coilover track performance question

[wpmarky]

Hi everyone,

 

I'd like to get some input from those tracking your spec.b on high speed road courses (since driving your car at the limit on public roads is a no no=p).

 

Currently i'm on Bilsteins/Pinks (2033021010) with the AVO RSB and LCA bushings. I do really enjoy this setup. It's comfortable as a DD, and is very agile and planted in the turns. On the track, it's great for the 80+mph sweeping turns, and is super stable on high speed straights. At the point where the tires loses traction, the car is sliding sideways, but pitched in the right direction so it's easily correctable with the throttle.

 

That being said, I'm looking for something stiffer since I plan on attending more road course HPDE's. I have a set of 6k/8k BC BR coilovers coming in. If the spec.b tranny is heavier than the 5mt, does that mean you should get stiffer coilovers in front as well? Should I not bother installing them and look for 8k/6k instead?

 

Or with the increased oversteer i'm expecting to get, can I counteract this with a stiffer front sway bar? Or should I welcome the increased oversteer and just power through those turns? Does understeer = slow on the track?

 

I'm probably going to just install them anyways, see how they feel, and adjust my driving accordingly, but any feedback or discussion would be welcome.

[Saul_Good]

I have the 6/8 springs on my MRs. You should be fine. Depending on your alignment settings, i wouldn't expect too much oversteer (excessive oversteer like you may be thinking). If you want, you don't have to buy different coilovers to get 8k/6k -- just swap the springs, on your coilovers. Unlike your fixed perch setup, the springs on the coilovers you bought are similar dimensions and can be swapped from front to rear and vice versa.

 

Just keep going to the track and make adjustments as u see fit. You'll be fine, maybe i'll run into you at Buttonwillow one day.

[wpmarky]

Good to hear, thanks for the tip on swapping springs... that does make sense too. I wasn't expecting massive oversteer, but enough to throw off my current feel for the car.

 

I do like how the weight of the car settles during hard turning right now with the pinks, and was hoping to maintain that same weight balance, just with stiffer springs. When there's 3-4 turns in a row, the pinks still have some wobble to it, taking a second or two to settle before i can give it more throttle. I'm hoping the coilovers will settle the car faster, so i can gas it sooner.

 

If you make any plans to go to BW, let me know. I'm itching to go there some time this year maybe once or twice.

[Drew888]

Currently i'm on Bilsteins/Pinks (2033021010) with the AVO RSB and LCA bushings. I do really enjoy this setup. It's comfortable as a DD, and is very agile and planted in the turns. On the track, it's great for the 80+mph sweeping turns, and is super stable on high speed straights. At the point where the tires loses traction, the car is sliding sideways, but pitched in the right direction so it's easily correctable with the throttle.

 

What are the rates of the Pinks, curious.

 

That being said, I'm looking for something stiffer since I plan on attending more road course HPDE's. I have a set of 6k/8k BC BR coilovers coming in. If the spec.b tranny is heavier than the 5mt, does that mean you should get stiffer coilovers in front as well? Should I not bother installing them and look for 8k/6k instead?

 

8k/6k should be fine. For a sedan I'd still still to the same rate front to rear.

 

Or with the increased oversteer i'm expecting to get, can I counteract this with a stiffer front sway bar? Or should I welcome the increased oversteer and just power through those turns? Does understeer = slow on the track?

 

Relative to your current set up it will induce a bit more oversteer. That's not a bad thing, and you can easily adjust via the front/rear bars and coilover settings. Understeer = sloweeerrr

 

I'm probably going to just install them anyways, see how they feel, and adjust my driving accordingly, but any feedback or discussion would be welcome.

 

 

What alignment settings are you using?

[Drew888]

Personally, I'd avoid a higher spring rate in the front.

 

Also, let me know when you are going

[wpmarky]

According to this site, my pinks are 257/217.

 

http://shop.edoperformance.com/sti-pink-springs-frontrear-legacy-p-9386.html

 

Coming from Ralliteks, which I think are softer in front, I saw a noticeable difference between the ralliteks and pinks.

[SubyShop.com]

The static spring rates of the stock springs have the rears stiffer than the front. I am pretty sure this is the case for STI pink springs as well. The reason behind this is due to the mechanical advantage imparted by the multi-link rear suspension. The rear spring rate seen by the suspension is less than the static rate.

 

6k front, 8k rear should result in a very similar balance to what you have right now.

 

You might be surprised if you add a stiffer front sway bar too. In my experience, it helped turn-in and improved the car's responsiveness. MacPherson strut ftl heh

-Franz

[AZP Installs]

I would suggest the Tarmac 1 RCE coilovers. Also have you done all the other bits to make it better handling on the track besides coilovers?

 

Bushings are key. Before going the coilover route, I'd exhaust all the other items that you can such as the LCA Bushings, Roll center kit, rear diffy locking bolts/bushings, steering rack bushings, etc. etc.

 

They made a big different on my 05 LGT Wagon that I track a lot. My last setup had all those bushings coupled with WL Front and rear sways and Group N Tops in front and Konis w/STi Pinks. Really was a wonderful setup. Now that I've exhausted all the other options I'm stepping up to the RCE Tarmac 1 coilovers for this coming season.

 

-mike

[SubyShop.com]

Good point, Mike. poly LCA bushings and poly steering rack bushings are probably the best bang for the buck as far as suspension bushings go. What rates are you getting on your RCE coils, Mike?

-Franz

[AZP Installs]

I haven't looked too deep into rates yet Franz. Any suggestions? The coils will be on for track/summer spirited driving only. Winter I will swap in the stock setup when I use it as a DD. For the spring-summer-fall, the CTS-V is on DD duty.

 

-mike

[Drew888]

I'm on 7k/7k and sometimes wish it were 8k instead. More and you are going to beat yourself up on the street.

 

I'm really liking my RCE Tarmac 1's. going stiff on them works very well and they can easily be softened up for DD use but...tarmac 2 add rebound adj. that I wish I had. I haven't looked into the price difference but I may next year.

 

Beyond the suspension I'm entertaining a larger oil pan (accusump would be nice), STI radiator, and waiting for the RCE 08 STI/WRX brake ducts.

[AZP Installs]

How about an oil cooler? I am planning on doing an oil cooler before the pan on mine. I can't wait for those brake ducts as well. I will likely need a radiator soon too.

 

-mike

[SubyShop.com]

The RCE's come with 400 lb/in springs normally, right? If they have some stiffer ones available, I think that might be a good thing, and try to go a bit stiffer in the rear. It sure is fun driving Clint's STI that has 500+ lb/in springs on it with Koni dampers (Ground Control c/o). With a quality damper, the ride is firm but it's not jarring. The rates he's running are nearly 10 kg/mm and it's his daily driver. For dd, I like the more supple ride of my car with Bilsteins/pinks. Personal preference of course. hehe

 

If I do any engine work, I'll probably go with a larger capacity pan and upgraded oil cooler. The cooling system has been no problem with routine maintenance.

-Franz

[AZP Installs]

I'm actually getting some temp rises on my car when I track it if I'm pushing it at 10/10th on track. As soon as I throttle it back to 9/10th then the temps drop down.

 

-mike

[Drew888]

Exactly what I have heard and I'm not taking any chances. I'm also installing a FMIC soon and a radiator upgrade will then be needed.

 

I thought of a cooler first until I read more about the pan. From a strictly cooling stand point I would think with a pan or cooler will net similar results by themselves. Going with a pan adds better baffling. With this extra benefit I'd tend to lean this way. Of course both is ideal, if maybe a bit overkill.

[Drew888]

The RCE's come with 400 lb/in springs normally, right? If they have some stiffer ones available, I think that might be a good thing, and try to go a bit stiffer in the rear. It sure is fun driving Clint's STI that has 500+ lb/in springs on it with Koni dampers (Ground Control c/o).

 

Is Clint running different rates front to rear, curious? Why a bit stiffer in the rear?

 

If I do any engine work, I'll probably go with a larger capacity pan and upgraded oil cooler. The cooling system has been no problem with routine maintenance.

 

Many have seen temps rise as much as 10* over when upgrading to a front mount so take that into consideration (some only a few, some up to 10+). Many accounts on NASIOC & IWSTI.

 

-Franz

[AZP Installs]

I also thought about a pan, that may be in my future as well the cooler is a lower cost of ownership I think.

 

-mike

[FPerron]

You guys are not being very clear about what you mean by "high temps" or "rising temps." Are you talking about cooling system temps, oil temps, intake charge temps, or underhood temps? I, personally, have not experienced or heard of many Subaru engine failures related to oil temperature - so I question the value of oil coolers or larger oil pans for street cars that are tracked from time to time. However, I know from experience that high intake temperatures can be very damaging. Consequently, I'd put water/meth injection at the top of my list of modifications designed to prevent heat damage to engine internals. Larger, more efficient radiators also make sense. I didn't realize that the STI unit was bigger and would fit. Finally, it would be great if we could figure out a way to vent hot air from under the hood. Unfortunately, the only way I can see to do that would be to cut vents into the fenders just in front of the doors - like the Subaru rally cars have.

[SubyShop.com]

Is Clint running different rates front to rear, curious? Why a bit stiffer in the rear?

 

Many have seen temps rise as much as 10* over when upgrading to a front mount so take that into consideration (some only a few, some up to 10+). Many accounts on NASIOC & IWSTI.

 

On his car he's running stiffer rear rates with big sway bars front and rear. 400 lb front, 500 lb rear. Keep in mind the 04-07 STI's have different rear suspension than our Legacy. Clint and I have different driving styles so our cars are set up a little bit differently. I'm a firm believer in running stiffer rear spring rate on the Legacy due to the multi-link rear (stock is this way too). My car is neutral and very predictable, even in snow and rain, with good turn-in. Clint's car is more tail happy because of the MacPherson setup all-around.

 

Ahh, I can see FMIC's causing problems with cooling. Is an STI radiator much of an upgrade for cooling? I haven't read into it much since I am sticking with a top mount setup. I know some guys go with Koyo units when they upgrade the radiator.

 

Extremely high g-force loads can cause short-term oil starvation to the engine. A baffled pan would be a good idea for cars that see a lot of track duty. Oil temperature is not a big deal unless the oil thins out too much and isn't offering good wear protection. A thicker weight oil is probably the best solution. 5w40 Rotella synthetic is popular and inexpensive.

 

-Franz

[AZP Installs]

Maybe I'm wrong but from my experience and research, higher Oil temps will lead to higher coolant temps. If you cool down your oil, your coolant temps will also go down. Hence the Oil Cooler setup. I am pretty slow at doing upgrades so I usually wind up doing 1 at a time, so my plan is to put in an oil temp gauge and then do some testing and then re-test after the oil cooler. So we should get a good feeling on how well the oil cooler is helping cool down the engine.

 

-mike

[SubyShop.com]

That makes sense. If the oil temp is higher, the engine is running hotter. The coolant temp will go up too. Will be interesting to see how much of a difference an upgraded oil cooler will affect the coolant temp. I usually run a mix of pump gas and race gas for track days to drop the cylinder temps down a bit. I'll be switching to E85 this spring so that should help even more.

-Franz

[Drew888]

What ratio in a typical mix? What is common?

 

I have only "heard" the STI radiator is two core to our one and bolts up (at least 08 STI to 08 LGT). If so then it's a big enough difference.

 

Sorry, I was referring to coolant temps.

 

FPerron, what is considered high enough intake temps to worry about? I'm not even going to try to self tune so I leave that to others.

[FPerron]

I have no idea what intake temperature is required to melt engine internals - but I know it happened to me.

 

After a season of pretty hard running on road courses, I noticed increasing oil consumption. Fearing a ringland problem, I did a leakdown test that showed excessive blowby. When we tore down the engine, we found no broken ringlands or other evidence of detonation. It just looked like everything got too hot with burned valves and warped piston aprons. We concluded that I was pushing my smallish (40BB) turbo outside of its efficiency range thus generating high intake temps that the Perrin TMIC couldn't handle.

 

Road racing is much more stressful on a motor than is any kind of street driving or drag racing. In road racing, you're doing repeated long WOT runs and are never really giving the engine a chance to cool down.

 

I rebuilt the motor with Wiseco pistons and tuned for water/meth injection and 100 octane gas. No problems since.

I reb

[SubyShop.com]

What ratio in a typical mix? What is common?

 

I have only "heard" the STI radiator is two core to our one and bolts up (at least 08 STI to 08 LGT). If so then it's a big enough difference.

 

Sorry, I was referring to coolant temps.

 

FPerron, what is considered high enough intake temps to worry about? I'm not even going to try to self tune so I leave that to others.

 

Well at Road America I was going through a 1/4 tank of gas per 20 min session. so I made sure to have at least a half tank of pump gas to start and then added a few gallons of race gas. Somewhere around 1/3 race gas 2/3 pump gas I'd guess.

 

Since I do HPDE and not timed high speed events for the most part, I play it safer and run richer AFR's for track days and drop the boost down a little bit (18 PSI). Knock on wood so far.

If you have an accurate EGT gauge, I think that would be the best indicator for seeing if your engine is at risk for meltdown. With E85, I'm expecting to hit MBT before seeing knock, so I'll run basically the same tune for track days and street.

 

-Franz

[AZP Installs]

I am getting those high temps at 10/10th on a completely stock driveline. My guess is the oil is heating up from the higher RPMs. I do HPDEs also with mine so to drop back to 8/10th isn't a big deal.

 

-mike