Proformance driving school at Pacific raceways

[suberdave]

i took the class today, all i can say is IT IS AWESOME!!!!!!!!!!!!! if you can, take the calss.

 

the track is awesome, i learned things about my car that i never knew. unfortantly my car with the EJ20G and Z4 ECU tops out at 118mph. but thats about all the faster i want to go anyhow... for now.

 

 

well i put on a total of 93 miles at the track 14 of witch were the cone training stuff and the rest of them were on the track. total of 3 different heets at about 10-12 laps on a 2.25 mile track. at about 2 mins a lap thats just shy of 1.5 hours of track time total. and 1.5 hours of watching the other group on the track.

 

went through $70.00 of gas @ $8.25 a gallon.

 

and totaled just over 10 miles a gallon. thats less than half of what i normaly use on the street...

 

added some ware and tare on the car. as far as tires they got beat up a bit. but they have 2 auto X's on them and about 20K street miles. but they still have lots of tred. just a bit of chunking, mostly on the right front.

 

and brakes are just fine. even with hard brakeing for 100 miles, they are just fine. however i did find out that with the new welwoods in the front, going from a single piston caliper to a 4 piston caliper, the stock master just dosent push enough brake fluid under a hard stop. never had any problems under normal driving, but when i tryed to do a panic stop (during one of the drills not on the track) from 70 mph, i could not lock up the brakes right away... not locking up the brakes is a good thing. but if i cant lock them up, that means i am not getting the full braking power out of them. and trust me when going into turn 2 at just shy of 120 mph i need all the stoping power i can get.

 

ill try to get some pics up and post them soon, i also have some video, but i have to rip it off of DVD first...

 

over all - well worth the time and money!!!!

 

-=Suberdave=-

www.suberdave.com

[subynut]

Now, that looks like fun! Can't wait for the pics and vids!

[GLCraig]

It sounds like you had a lot of fun. Did any of the instructors have a WTF look on their faces when you showed up in a Leone wagon?

[daeron]

brake fade can be combated by adding stainless steel brake lines to replace the rubber hoses.

 

You might want to look into the possibility of retrofitting a master cylinder out of a Nissan.. Say a 280ZX, 300ZX, Maxima, or pickup truck. I have no REASON to believe they would swap easily, but subarus and nissans are first cousins when it comes to cars.. probably more closely related than any other two independent Marques. Just a thought.

[calebz]

Curious about the 118 limit. Is that a speed/rev limiter, or do you run out of gears?

 

What gas were you using for the track time?

[Virrdog]

Congratulations. That is the best performance mod you can do for your car! Tighten up the loose nut behind the wheel.

 

Oh, and I get about 5-6 mpg when I am at a track day with my BC Turbo Legacy. That gets spendy at $6 a gallon.

[suberdave]

brake fade can be combated by adding stainless steel brake lines to replace the rubber hoses.

 

You might want to look into the possibility of retrofitting a master cylinder out of a Nissan.. Say a 280ZX, 300ZX, Maxima, or pickup truck. I have no REASON to believe they would swap easily, but subarus and nissans are first cousins when it comes to cars.. probably more closely related than any other two independent Marques. Just a thought.

 

i have 4piston welwood calipers and 12" disks in front, and i do have stainless lines. i didn't have any problem with brake faid. just a bit of a soft pedel due to small diameter master cyl. my GL cyl is only .8125" diameter, witch is fine to push the single piston brakes. but an STI has a 1.0625" diameter master to push the Brimbo's...

 

i have got an STI master on the way...

 

 

Curious about the 118 limit. Is that a speed/rev limiter, or do you run out of gears?

 

What gas were you using for the track time?

 

the 118 speed limit is a speed limiter, not RPM limiter. RPM's were only about 5800 and pedal was only at maybe 20%.

 

-=Suberdave=-

http://www.suberdave.com

[crazyhorse001]

Track time is just SOOOOO much fun!

 

Add to that, there's no substitute for "seat time" to improve your at the limit skills.

[daeron]

are you spending extra money on high octane race fuel in a vehicle that normally sees daily driver status? If so, what octane fuel do you normally run on the street? Did you make any timing adjustments to take advantage of the high octane?

 

The entire purpose of high octane race fuel is to dial back your timing and run less advance. The high octane fuel merely has a higher anti-detonation rating, and can tolerate less advance before pinging. All things being equal, Less advance = more power. However, without high octane race fuel you cannot retard your timing very far from stock settings before you get major pinging. It also takes careful adjustment, and good info on your engine (ie, knock sensors and wideband O2) to do it properly.

 

In other words, if you just plunked $6-8/gallon race fuel into your DD that normally sees 91 octane and runs fine on it, you wasted $3-5/gallon on race fuel.

 

My brothers own a fully ITS prepped 71 240Z. They run standard pump 93 octane in it, because they haven't yet gotten the wideband O2 sensor and mixture gauge to put in the thing. It runs like a champ.

[suberdave]

are you spending extra money on high octane race fuel in a vehicle that normally sees daily driver status? If so, what octane fuel do you normally run on the street? Did you make any timing adjustments to take advantage of the high octane?

 

The entire purpose of high octane race fuel is to dial back your timing and run less advance. The high octane fuel merely has a higher anti-detonation rating, and can tolerate less advance before pinging. All things being equal, Less advance = more power. However, without high octane race fuel you cannot retard your timing very far from stock settings before you get major pinging. It also takes careful adjustment, and good info on your engine (ie, knock sensors and wideband O2) to do it properly.

 

In other words, if you just plunked $6-8/gallon race fuel into your DD that normally sees 91 octane and runs fine on it, you wasted $3-5/gallon on race fuel.

 

My brothers own a fully ITS prepped 71 240Z. They run standard pump 93 octane in it, because they haven't yet gotten the wideband O2 sensor and mixture gauge to put in the thing. It runs like a champ.

 

First off I don’t think I was tossing money into my gas tank. I am using the JDM ECU and it is tuned for 100oct. normally I run 92-93oct. but I am not running at 100+mph for 20-25 minuets at a time.

I feel that buying race gas is cheep insurance for detonation.

I’m not trying to start a debate. But I think you have it all wrong. The reason you run higher octane is so you can run your timing more advanced. The higher the octane rating the less volatile the fuel is and the harder it is to ignite. This you can run more advance and higher compression without detonation.

When I run race gas in my tank my car runs much better and has better response. I don’t think for a minute that I wasted any money. And next time I go out to the track I will put race gas in it again. Just like I did this time and like I will every time I go...

-=Suberdave=-

www.suberdave.com

[86BRATMAN]

The entire purpose of high octane race fuel is to dial back your timing and run less advance. The high octane fuel merely has a higher anti-detonation rating, and can tolerate less advance before pinging. All things being equal, Less advance = more power. However, without high octane race fuel you cannot retard your timing very far from stock settings before you get major pinging. It also takes careful adjustment, and good info on your engine (ie, knock sensors and wideband O2) to do it properly.

 

You just said the opposite of everything I know about ignition timing.

[cubastreet]

Yeah, high octane fuel burns slower, so more advance is needed for maximum power.

Less advance is theoretically better but any fuel that burns fast enough to set the timing to 0 at high revs will detonate like mad

[daeron]

my understanding was that to get maximum power, you want to detonate as close to TDC as possible; the more degrees advanced you are, the further away from TDC you are, and the more of your explosion gets routed out the exhaust valve instead of imparting downward force on the piston.

 

Higher octane fuel is more resistant to detonation from compression. In other words, you can wait longer before you have to spark it. the higher the static compression ratio of the engine, the more detonation prone; thus, either high octane or more ignition advance is required.

 

Am I wrong in these statements?

 

If so then I have some serious hunting to do, because these misconceptions (if such they are) sure make a hell of a lot of sense to me, and I want to find where I was steered wrong.... I am going on a brief search and re read of some of my bookmarked articles to see what I can find before bed, but if I AM wrong someone please steer me right.

[Numbchux]

Higher octane fuel is more resistant to detonation from compression. In other words, you can wait longer before you have to spark it. the higher the static compression ratio of the engine, the more detonation prone; thus, either high octane or more ignition advance is required.

 

The simple side of it is, Higher octane fuel burns slower, and therefore must be ignited sooner.

 

for more information than your average joe (like me) can understand, go here:

http://en.wikipedia.org/wiki/Octane_rating

[cubastreet]

You've got it all right except that advancing the ignition makes the spark sooner, so the flame doesn't go out the exhaust port. e.g. 10 degrees before top dead centre (BTDC)

 

The problem is that starting the flame too much before top dead centre means that the gases start expanding while the piston is still going up, reducing power output.

 

Ideally you want all of the gas to start burning right on top dead centre, but not detonating. You want all the gases burned up at the moment you hit bottom dead centre. What you get in reality is a flame starting from the spark plug and then spreading through the combustion chamber, and generally still burning when the piston starts rising.

 

So what you really want is a relatively fast burning fuel that resists preignition (compression ignition) and detonation (where it explodes and blows holes in pistons).

[Durania]

You all should take it to Mythbusters.

 

I dont know what to believe.

[calebz]

The simple side of it is, Higher octane fuel burns slower, and therefore must be ignited sooner.

 

 

Actually, the term that covers the rate/completion of the burn cycle is deflagration, which is in no way affected by octane rating

[calebz]

 

The entire purpose of high octane race fuel is to dial back your timing and run less advance. The high octane fuel merely has a higher anti-detonation rating, and can tolerate less advance before pinging. All things being equal, Less advance = more power. However, without high octane race fuel you cannot retard your timing very far from stock settings before you get major pinging. It also takes careful adjustment, and good info on your engine (ie, knock sensors and wideband O2) to do it properly.

 

 

100% correct - except that it is completely rump roast backward.

[Virrdog]

Am I wrong in these statements?

Uhh, yes.

my understanding was that to get maximum power, you want to detonate as close to TDC as possible;

No. You want maximum cylinder pressure near but after TDC so the force will push the cylinder down. Right at TDC there is less leverage on the crank, when the crank lobe is approaching 60-90 degress from that cylinder is where you want the most push.

the more degrees advanced you are, the further away from TDC you are, and the more of your explosion gets routed out the exhaust valve instead of imparting downward force on the piston.

Think about what you just said. Why would the exhaust valves be open on the compression stroke before ignition? The valves open after the ignition event, so the more advance (which means the cylinder sparks before the piston reaches the top) would mean less explosion is around when the exhaust valves open.

Higher octane fuel is more resistant to detonation from compression. In other words, you can wait longer before you have to spark it. the higher the static compression ratio of the engine, the more detonation prone; thus, either high octane or more ignition advance is required.

More resistant yes. Wait longer, no. The more detonation prone the engine the higher the octane or LESS ignition advance needed.

 

Gas burns at a certain rate. So there is a certain amount of time you want to allow it to burn and expand before the piston reaches top dead center so it pushes down with the most force. There is a general advance timing that allows this at certain rev ranges (the faster the engine is moving the faster you need to ignite the gas to allow it time to expand, that's why almost all engines have timing that advances with revs).

 

The problem with too much advancing is that the gasoline mixture is easier to combust out of control at lower pressures. The more advance means the lower the cylinder pressure when sparked. High octane allows you to run more advance to reach the timing sweet spot because it resists this out of control burn.

 

Hope all that makes sense. Less advance means farther away from the sweet spot and the gas has less time to burn and expand. As I mentioned in the paragraph above, more advance means more pre-detonation prone... thus the use of high octane fuel.

 

And since the original poster has a turbo car at a track, super high octane is the proper way to go. Heat adds to pre-detonation risk. There is a LOT of heat coming from the supercharged air AND everything is hotter driving hard at a track. 98+ octane is the way to go. NA cars can sip something milder typically, but who wants a NA Subaru at a road course? Not I!

[suberdave]

Open your hood in the pits. After sitting with the hood closed the IC becomes an interwarmer and all 3 subies had "misfire cyl 4" CEL's after lunch. That = det. Once we started opening the hood there were no more problems.

 

this was posted over at the Impreza board, from a board member that has gone and was posting some "info he would have liked to know before he went to the class"

 

turbo car at a track, super high octane is the proper way to go. Heat adds to pre-detonation risk. There is a LOT of heat coming from the supercharged air AND everything is hotter driving hard at a track.

 

this i agree with 100% and like i said. everytime i am going to run my car hard i will spend the $ for the high oct fuel...

 

-=Suberdave=-

http://www.suberdave.com