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Southwest Montana SCCA discussions for the 2003 season.
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RayAR
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Postby RayAR » Tue Aug 26, 2003 5:07 pm

I had as much camber as I could get at the Ice garden. It helped but I was still on the bump stops and they are a pain to trim. I don't think the Cossie has an understeer problem at all, at least I didn't notice it on the rides I took. If the Cossie has an understeer problem then my Stealth is very bad.

Russ is right about driving, You will notice drivers like Joe E., Norm(CRX), Ken Decker(Billings) and Jeff Richie(didn't race this year) are all very smooth drivers. Most of the time they don't even look fast but are still knocking down very good times. I am sure I left other smooth drivers out of that list but those are the ones I can think of just off of the top of my head. These are the people I want to be able to drive like. Concentrate on being smooth and running the correct line and you will only get faster.
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Postby WRX-B » Tue Aug 26, 2003 9:55 pm

I was seeing the Cossie's understeer on the uphill left hander at the Garden. Watching from the doors of the building, it looked pretty pushy. (i gots plenty understeer there too, especially on the first lap through). Its all good. After Ruskel runs the STi, the Escort will be a distant memory anyway :wink: :wink: :wink: :shock: 8) :wink: Trouncing everyone will be too fun for him.

Russ- what differential setting you gonna beat us with? :?:

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Postby rkaiser » Wed Aug 27, 2003 12:21 am

Thats where I was getting some serious turbo lag when trying to go up the hill in second gear. This car will understeer in that condition. When I started to shift into first in my later runs (third set of runs and buck runs) I was able to keep the rpms up and go much, much faster - over 2 seconds faster - and no understeer. I bet my last run would have been a 40.2 if I haden't missed my shift into second coming out of the last corner. If I could just keep this thing in it's power zone it would be awesome! The transition between no boost and 20 PSI of boost that worry me! Hopefully tweaking the ignition timing on the ECU will help get more low end power and soften the power and torque curves a bit so the transition isn't so brutal.

I've been playing with the center diff on the STI and to be honest I think I like it set to open (34-65 split) and not on Auto. I think I just need some time to get used to the auto but right now the car seems to handle better and more predictable in open mode. Maybe if we get enough runs I'll try both. However, I'm loving the low rpm torque and power - this thing is going to scream ouot of the corners!

The Cossie will never be forgotten - look forward to it doing some serious spanking on street tires next year :D
Russ

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Postby WRX-B » Wed Aug 27, 2003 11:34 am

Good anti lag systems are only several thousand dollars, git some!! :D

I read in one of the car mags where a guy was autocrossing the STi, and at first he left it in auto mode and found it had a touch of understeer coming out of corners. Then, he switched it to the mode you are thinking about and the understeer was gone, and he went way quicker too. Can i borrow that whole driveline off of ya Russkel?

Also, in the same article, the guy got to take the STi to the dragstrip. He did a bunch of races against alot of cars and even though he wasnt getting the best launches, he was spanking everyone. Eventually, he figured out that the tranny was so freakin tough, he could drop the clutch at high revs- no problems at all. I could do that, once. Blamo.

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Postby RayAR » Wed Aug 27, 2003 2:59 pm

WRX-B wrote:Good anti lag systems are only several thousand dollars, git some!! :D


Much cheaper then that. Just keep our right foot on the floor and brake with your left foot. I still need to give that a try and run 2nd gear. It will overpower the brakes in first I even think it might in second.
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Postby WRX-B » Wed Aug 27, 2003 10:02 pm

Good ole two footin!

I practiced LFBrakin quite a bit before last event. Only managed to do it once, around that single cone. I didnt do it very well though. I didnt have the nads to use the left foot to brake going into the downhill chicane. Oh well, i suck.

Never thought i would ever run in second gear at the Garden. It feels soo slow, but the times are good. When i have a passenger with me lately, i feel like apologizing, feels so uneventful. 1st gear just feels more violent, its louder too, i spose. Them tiny falken tires helped out a bunch, gonna run them in Billings. Hopefully, they will be the right choice.

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Postby rcurrier44 » Thu Aug 28, 2003 10:45 am

Sounds like you turbo guys need to drive an old farm truck with worn out sinkros (?sp?) for a while. Man ya gota heal-toe keep those turbos spooled up. Most of the guys I have seen don't just keep a high RPM they tap on the throtle, bliping the engine as they brake and turn. Just keep the clutch in and time the clutch release so your creating good pressure when you are ready to power out of the turn. It takes lots of practice.

Persionaly I heal tow around town all the time. Mostly in my 4X rig since the RX7 has been down for so long. But I have gotten good enough that I don't need the clutch to shift and when stoped on a hill I can move from holding the truck there with the brake to using the clutch & back to brake without the rig moving at all. Just takes practice :P

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Postby RayAR » Thu Aug 28, 2003 1:12 pm

Rob,
Turbos don't create boost unless the engine is under load. I can hold the throttle to the floor with the engine a 7000 and maybe have 1 PSI. You can pre spool turbos by blipping the throttle a few times and that is the technique I use at the starting line. It would be tough to find the time to do it on the course and I bet it would be very hard on clutches and I have enough clutch trouble the way it is. If I keep the Revs over 3000 RPM my car has virtually no lag. I have a feeling I could keep the turbos spooled by left foot brakeing but it would be hard to get my car to slow down. I guess I just don't understand how heal toe shifting would keep boost. Are you sure you haven't watched F&F II a few to many times? :P :lol:

Both my old 74 chevy 94 GMC and CJ5 when it was a manual where easy to shift without a clutch and I used to do it all the time. My car is very difficult to do that with and I would be replaceing syncros on a regular basis if I tried it. I have heard of a company that makes a dog engagement gear set for my car. It would allow no clutch High RPM shifts but you would have to rev match downshifts and it would be very harsh for a daily driver. I doubt it would make me any quicker.
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Postby rcurrier44 » Thu Aug 28, 2003 2:27 pm

Maybe thats why "Most of the guys I have seen don't just keep a high RPM they tap on the throtle".

Maybe these guys had different turbos - or tricked there turbos into thinking the car was under load. You say you blip your throtle before takoff inorder to spool up the turbo - that is not creating boost? or is it turning the turbo and just dumping it into the air untill you drop the clutch and load the engine? So you cars turbo has a clutch on it that is vacume activated? Why would this not work on a turn?



Sounds like you tranny probubly has more holding power than a MR2 or RX7. Both Ridgleys and my car can be power shifted. (or maybe our trannies are worn out) :?

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Postby RayAR » Thu Aug 28, 2003 5:41 pm

Well Rob,

I will try to explain it but not sure if I will do a good job. First the F&F remark was just fooln' with ya but I thought it was pretty funny :lol: An engine just dosen't flow enough air or produce enought heat to make a turbo spin fast enough and produce boost when not under load. I know that many turbo cars that drag race will use a rev limiter to build a little boost at the line but it is still only 1 or 2 PSI. Now you ask where the air goes when I am blipping the throttle at the line. A turbo car needs a blow off or bypass valve(mine has a bypass) that will release the pressure when you close the throttle. Without that valve the turbo would get very bad compresor surge and it would destroy the turbo. A blowoff valve is open loop and will release the pressure into the atmosphere. A bypass is closed loop and releases the pressure into the turbo inlet. A bypass is also suppose to leak under vacuum. Basically I am releaseing all of my pressure back into the turbo inlet. No........ I am not getting any boost but I am getting the turbos spinning pretty darn good ready to pressurize the system as soon as I floor the throttle and release the clutch. They still aren't spinning as fast as when the engine is under load but it helps. You are welcome to watch my boost gauge when I am blipping the throttle. I gaurentee that it will be going between the 0 mark and 15 inches vacuum mark.

Not sure how much of that helped but an engine is an air pump and it just dosen't flow much air unless the engine is under load. Without airflow the turbos don't spin very fast. Did you know that crank driven superchargers also don't build boost unless they are under load but when it does build boost it is instant. I think a lot also has to do with throttle opening. It dosen't take much throttle to cruise at 3000 RPM so there is very little opening that the supercharger can suck thru so it dosen't build boost.

Now lets clarify powershifting. Do you consider powershifting shifting without the clutch and at full throttle or useing the clutch at full throttle? I consider it the second one Useing the clutch at full throttle. I can do that with my car but I don't because if I miss the gear I can almost gaurentee I just destroyed a syncro. It's just not worth a broken trans for maybe 1/1000 of a second improvment. The first method would only work on specialy built race trannies that had dog engagement gears or modified syncros.

I have seen racers blip the throttle when downshifting and I even try to do that because it makes for a super smooth downshift when I do it right. Not very often :oops: That is where heal/toe brakeing would come in handy instead of trying to do the 3 pedal dance :D


Oh, I almost forgot. My car gets 15 PSI in 3rd gear around 3000 RPM. Guess where it get that same boost in 5th gear....... just a bit over 2500RPM. Why? More load on the engine, more airflow, more heat. And one more thing. Most of the real high horsepower turbo cars, We are talking 800+ at the wheels, are making more horsepower in 5th or 6th gear(overdrive) then they are in 4th because it puts more load on the engine. Something to think about.
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Postby rcurrier44 » Fri Aug 29, 2003 10:13 am

Sorry Ray, I don't know what F&F stands for :?:



"An engine just dosen't flow enough air or produce enought heat to make a turbo spin fast enough and produce boost when not under load"

Ok I just don't buy this. Why woulden't an engine flow a different amount of air under load vs not under load? It is still the same size cylinder, valves etc - moving at the same rpm. Its just a pump. Why is this different under load vs not? Its probubly something I don't understand about engines, I hate engine work because I realy don't understand them. This might have something to do with the fact that you have more vacume under load?

I didn't relize a turbo bypass droped you to zero psi when dumping/looping I assumed they had a pressure reducing relief valve like on hydraulics that simply prevents spikes.


"You are welcome to watch my boost gauge when I am blipping the throttle. I gaurentee that it will be going between the 0 mark and 15 inches vacuum mark."

So if you hold the throtle down the pressure bleads off, but when just blipping the throtle it rises while the engine RPMs rise?



Accualy I consider "power shifting" using the engine to match the rpm of the next gear you are going into - vs. most people push in the clutch and let the syncro match the RPM of the 2 gears. This allows me to be smoother when racing + heal-towing with the clutch; because I don't get a jerk in the drivetrain when transitioning from braking to throtle.

The "powershifting that you speek of - whare you shift at max RPM without droping RPM - doesn't work for my car on an autocross course. I tried it a bunch while at one of the icegardens races and everytime I released the clutch it would grab instead of smoothly slip & reingage. This would break the rear end free and try to spin me out. The fact that the poor little car has a 32lb flywheel doesn't help. I just coulden't be smooth with it.

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Postby rcurrier44 » Fri Aug 29, 2003 10:40 am

"My car gets 15 PSI in 3rd gear around 3000 RPM. Guess where it get that same boost in 5th gear....... just a bit over 2500RPM. Why? More load on the engine, more airflow, more heat."

I was also thinking about the vacume thing. Vacume is neg pressure. So if there was more load the engine should be creating more neg pressure = less final pressure at a specific RPM when your in that higher gear.

You refer to heat several times. Does more heat allow the turbo to flow more air? I always thought you wanted cool dense air? Or is this heat help more for the exhaust side than it hurts on the intake side?

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Postby JoeE » Fri Aug 29, 2003 10:55 am

Maybe I can help a little here. What makes the turbine (exhaust side) of a turbo spin (In turn spinning the compressor and making boost) is the energy contained in the exhaust gases as heat. Simply pushing air through the turbine would make it spin, but when the turbine spins the compressor spins, and when the compressor spins there is resistance because the compresser is trying to compress the intake air and jam it into the intake. So Rob you are correct in that what ever CFM the engine is producing at a given RPM (because it is an air pump) would make the turbo spin if there weren't anything resisting it. But the compressor is resisting it, so there needs to be more than just moving air to make boost. When the spent charge comes out of the combustion chamber is very hot and really wants to expand. A turbo takes advantage of that normally lost energy by allowing the exhaust to expand in the turbine housing.
Is that any clearer than mud?
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Postby rcurrier44 » Fri Aug 29, 2003 12:05 pm

JoeE wrote: So Rob you are correct in that what ever CFM the engine is producing at a given RPM (because it is an air pump) would make the turbo spin if there weren't anything resisting it. But the compressor is resisting it, so there needs to be more than just moving air to make boost. When the spent charge comes out of the combustion chamber is very hot and really wants to expand. A turbo takes advantage of that normally lost energy by allowing the exhaust to expand in the turbine housing.
Is that any clearer than mud?



Ah, I see now. That is ware the heat comes into play. It acualy explanes alot. I had always assumed that turbos created a mechancal increase in pressure between exaust and intake - more like the relationship between the crank and compressor on a supercharger. I guess I never relised that the exhaust gasses were that much hotter when the engine is under load than not.

I guess that is why people say that a turbo engine is so efficent (?sp?), since it uses that extra heat......

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Postby RayAR » Fri Aug 29, 2003 12:17 pm

I do not get any boost when I am blipping the throttle. It is just a technique that most turbos guys that drag race use to get the turbos spinning pretty good(again, not anywhere near as fast as when the engine is under load). Like I said earlier, the only way I know of to build boost without a load on the engine is a rev limiter but you still will only see 1 -2 PSI.

An engine is an air pump but throttle opening is what will limit air flow. If you are cruiseing down the highway at 3000 RPM it will not flow as much air as if you suddenly opened the throttle still at 3000 RPM to pass someone. Try to think of it as trying to breath thru straws of different sizes. With a small straw(throttle barely cracked) you will have a hard time getting enough air. Breath thru a large straw (full throttle) and you could probably run a marathon.

Actually heat is good on the exhaust side of the turbo. Thermo tec even makes a turbo wrap to RETAIN heat in the Turbo and that is suppose to reduce lag. Keeping heat in the exhaust is even good for N/A engines.

Anyway, I am just getting ready to head out the door for the weekend so don't badmouth me to bad when I am gone :D See some of you on Monday.
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Postby WRX-B » Fri Aug 29, 2003 3:56 pm

I need a boost gauge. I kinda want one that actually clamps to my head and squeezes real hard on my skull to make me lift my right foot. Everyone would be safer driving around town.

When i had all my fun exhaust stuff done to my car this spring, i had a turbo 'blanky' put on as well. I went with a lil kit from DEI, they are very similar to Thermo Tec. Before i had Tim F. of Autoworks install all my junk, i wrapped my downpipe with 'header' wrap too. Besides going with the theory of keeping the exhaust gases hotter to aid in speedy flow, i was also trying to keep the underhood temps down a bit-- in order to keep my TopMountIntercooler from turning into a StupidTopMountHeatSoaker. <-- Thanks Subaru. :roll: Russ's STi has a neato IC water sprayer, i wont feel bad when he beats my time, even with two broken legs. (my legs) :lol: :wink: :wink:

Audi`O's. (thats dork for Adios)

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Postby rkaiser » Sat Aug 30, 2003 9:05 am

What a nice lively discussion about turbos and heat :D I've been thinking of wrapping my downpipe too. I have heard that it can make them brittle though. I'm not sure how much boost my turbo makes while sitting still. i think if i rev it too 5000 rpm I make enough boost that my BOV is venting when lifting off of the throttle.

The best way to get boost while sitting and at low rpms is the WRC trick and use anti-lag. The full blown WRC cars are making almost full boost when sitting at the starting gate! They do this with a modified idle control valve, throttle body and a ECU upgrade. Fuel is injected on throttle lift off and allowed to passd through the combustion chamber and is then ingnited on the hot exhaust manifold. Very tough on turbos and manifolds but they rebuild the engines a lot more frequently they we do! Looks pretty darn cool with the huge flames shooting out the exhaust! I think some of them are using exhaust gas now to keep the turbo spinning. Not sure how this works yet but it I'm looking into it.

Ricky - been thing of installing a intercooler spray on the Cossie too :D
Russ

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Postby WRX-B » Sat Aug 30, 2003 12:06 pm

bastage!
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Header wrap

Postby JoeE » Sat Aug 30, 2003 6:05 pm

So here's a question. Its obvious that you want to keep as much heat in the exhaust as possible from the exhaust port to the turbo, but what is the advantage of wraping any of the exhaust after the turbo? Except for Rick and his intersoaker right above the exhaust, it seems to me that a larger temperature differential from turbine inlet to turbine outlet would be advantagous. :?:
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Postby rkaiser » Sat Aug 30, 2003 7:07 pm

I was going to wrap the downpipe to keep the heat away from the ABS/brakes that are right next to the downpipe. However, since I got that heat sheild for the turbo/downpipe in place I don't need to wrap them anymore. I've seen some paint on ceramic coatings for exhaust manifolds. Any one with experience with that?
Russ

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Postby rkaiser » Sat Aug 30, 2003 7:49 pm

Joe - is the 911 back together and running?
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Postby WRX-B » Sat Aug 30, 2003 10:03 pm

Joe- heres some opinions for you from a bunch of WRXers. Basically, theres no way to know who to believe.

http://forums.nasioc.com/forums/showthr ... t=wrapping

Turbos- yuck. Makes me want an 2004 S4. 8) Or, maybe i just want one just for fun.

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911

Postby JoeE » Sun Aug 31, 2003 6:36 am

:D The ol' 911 is running again. Derek and I did the intial start-up and run in (20 minutes at 2000rpm, the neighbors loved it) thursday night. I've got a whopping 45 miles on it since. There is a bit of tuning to do, its carbureted, so it will be some work to get it running smoothly.
:D
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