lafrad

Well.. got back from my other car club's "international meet", and it involved an extended period of time at the Drag-strip. Of course, I was driving my new RX-8... finally has enough miles on it to screw around some... and all the Dodge guys wanted to see it..

Got 14 runs in, and a lot of playing around.

Quickest run: 15.301.
Fastest run: 90.70.

THe 15.301 was my FIRST run. (first time EVER on a track with a manual. I have run my intrepid many many times) Run on 89 octane pump gas, the little "fill" light was on. I was in a hurry, and wasn't able to fill up before the track. I tried to do a burnout, had massive wheelhop, so i shut down before I broke something or looked like a fool.

Launched at 3500 rpm fast clutch release (I NEVER dropped the clutch), massive wheel hop and stats:
60' 2.438
330 6.547
1/8 9.930 @ 73.35
1000 12.827
1/4 15.301 @ 89.82

I backed off the throttle in the '60, and I hit all my shifts pretty well.

My FASTEST run was much later in the day. I had learned how to do a burnout, and was in the burnout box in 2nd gear, not first. (much more smoke, so its better, right? :-P ) I was launching at 5500 rpm, and feathering the clutch to keep the rpms above 5000 so I wouldn't bog down. To keep wheel hop down, I put MORE air into the tires... (traction wasn't a problem AT ALL.. the track was VERY sticky.) I ended with 45 psi in the fronts, 40 in the rears. I would get a little bark in the 1-2 shift, but never was I wanting more traction. (next time to the track, maybe) Here are the stats for the FASTEST run:

60' 2.167
330 6.427
1/8 9.894 @ 71.22
1000 12.840
1/4 15.332 @ 90.61

I was really expecting MUCH better times/speeds after I figured out how to drive it, but I changed something mid-day:
Insted of leaving the track to go fill up with some premium (with 10% ethanol, YUCK), I decided to try some of the "race gas" 104 octane, unleaded.
I didn't really notice the difference there at the track, i was still learning how to drive it. and the 60' times show that. BUT, I went and filled up with some mid-grade for the trip home, and INSTANTLY the car came alive. It felt MUCH stronger on the mid-grade 89 than it did on the 104.

Next time I go to the track I will make sure to fill up before I get there.

Now.. time to go to the garage and scrape some rubber out of my wheel wells.

blksf8

I think you should be using premium fuel, not 89. In regards to fuel, you probably don't want a full tank of gas as it adds to the weight in your car. Maybe just have 1/4 tank max.

good write up. let us know how your next track day goes!

lafrad

I have no issues filling up with premium gas when I am going to be driving the car hard. but its hard for me to justify filling up at $2.19/gal for a trip where I just burn the whole tank up on the hiway, on cruize at 75 mph.

I would definately use premium at the track next time, but I won't be looking for anything higher than 91 or 92.

Also, ya need to start with more than 1/4 tank, because the 14 runs burned through a little more than 1/4... who knows how far you have to go to the nearest gas station ?

Lawerence

Nice runs.

Its wierd that your first run was faster than the other one.
I mean with that 2.4 60' you still got a better time, than with a 2.1 60'? That is very strange.

I think maybe the shift points are killing peoples times too. What RPMs where you shifting at?

also you wont see any real increase with the use of 104 octane (as you found out). Maybe 2-4hp MAX. Nothing you will feel.

lafrad

I really attribute my longer times to the race gas. I didn't use it for any reason other than the fact that it was convienent... and at $5/gal it wasn't very convienent either. As I look back on all the other times that I had, I noticed that my max MPH was faster on pump gas... the Race gas just had less energy overall...

About shifting: I was trying to shift by anticipating the buzzer.. so I would start to move my foot to release the clutch before the buzzer went off.. and by the time I was fully disengaged, the buzzer just rang and I had almost been in the next gear....

Omicron

Very nice write up.

TiTaniumRX8

Great job man, i had an experiance just like yours... accept my fastest time was a 15.875 my first day/time and every thing with the car... and at the track.... good job

Velocity-8

That's different. Usually you are supposed to drop the tire pressure to get better traction and less wheel hop. Did you try any runs at lower than stock PSI?


Here's my time slip from Atco on stock tire pressure...

I'm car #202

lafrad

First thing I tried was to drop the tire pressure to 26 psi... wheel hop got worse.

And traction wasn't a problem... I had a 2.1xx 60' time on 40 psi of Cold Pressure. Also did a monster burnout in 2nd gear before that run, so the tires were warm, with lots of pressure..... and that rumor of limp mode remains that... a rumor.. i don't think I experianced it.

Velocity-8

Wow, that interesting. Next time I go to the track I'll try playing with the tire pressure.

When I was at the track my first two runs set off a CEL and the car was in a limp mode. I turned it off for a few minutes then tried some more runs but with less aggressive burnouts. No more CELs after that.

jdmlover79

are you guys talking about rx-8 6spd times?

Velocity-8

My 8 is a 6mt, yes.

lafrad

I also hava a 6MT

Mike Ockstynee

If you dont mind me saying so...

Burnout was a waste of time and rubber. Regardless of what anyone tells you, if your tire has tread a burnout does NOTHING for you except wear your car/tire out.

If you get a pair of slicks you need a burnout... but pointless on factory tires

And here's the coolest part....the water from the burnout box will get caught in your tread and cause you to lose traction when you run...so you will run slower...

Cool, huh?

Velocity-8

Mike, you are totally correct. I cracks me up to see the Civics do huge burnouts before their runs.

Atco, where I run, there is no way around the water box. I do a quick 1-2 burnout to shed the water.

lafrad

that is nice to know.
Next time I will try it without.

I *do* have a hard time believing that it is not benificial in any way, shape, or form, as the OE tires get super sticky when warm, (I saw this at the track.. the rocks and such all stuck into the rubber after some of the larger burnout/agressive launch runs... sitting in the parking garage righ tnow, the tires are relatively "hard", and will not pick up rocks.)

Also,
Why the attitude? I can get all the information I need from a post from someone who isn't being a sarcastic *****. I have very limited Dragstip experiance, and the observations, and what I do, are based on observations and educated guesses. I am sorry that I don't have the "god" opinion about my knowledge, I will try to be more "god-like" in my posts in the future.

From what you say about the water getting caught in the tires, it seems to me that a non-water, 1st gear short "burn-out" would be the best way to go, knocking the junk off the soft rubber, and warming up what it can... while not getting wet.


That is all moot tho, if you launch as hard as you can without tirespin. Just like the pressure thing, if you arent going to spin the tires in the first place, why do you need more traction?

JKonquer

maybe somebody can answer this question, but every time i see best motoring from japan. they launch their car by revving all the way to redline. and they feather the clutch. therefor you don't really burn out and still keep the high rpm after takeoff.
Most of the times people don't drop their clutch.

lafrad

I STILL want to have a clutch left to drive home....

visitor

how's premium gas gonna help his quarter mile time?

visitor

if you can get white smoke coming off your tires from a burnout, i don't see how water could still be trapped in the treads.

Tony Orlando

If you want to avoid tire pressure lights or limp mode, just put all 4 sensors in your spare, air it up to 32 psi, throw it in the trunk and forget about it. Now you can run whatever pressure you want.

Velocity-8

If you overheat street radials they become slick and loose their traction. If there is a waterbax like Atco that you can't avoid then a quick burnout is enough to shed the water. Too much and your launch will suffer.

Richard Paul

iTrader: (5)

Lets talk about that fuel. The least octane you can get away with will make the most power. Now, the problem is that you don't have control over the spark. If the octane is to low and the car goes into knock the knock sensor retards the spark and you lose power. If you have extra octane the only way to get more out of it is to advance the spark. This is because it burns slower. The knock sensor will not advance it over the spec setting.

The idea is not to run a lot of advance, that is a cure, not a power tactic. Think what you are doing. You are putting pressure in the chamber while you are still compressing it. Based on the 10 to 1 compression of the 8 you will not need more than 89 octane. But since chamber shape changes these things the only way to find out is on the dyno.

Of course you could just make several runs with all the octane gas available. If you can find a way of locking the spark at a given point it will help. BUT only do this if you know what you are doing as you will hurt the engine if you go overboard.

Just remember more advance is not a goal. Just enough to burn the mixture completly. There is a small spot to land in. Without dyno data maybe you better stick to trying the different fuels. Thus letting the computer save you from disaster.

Now I had a hard time getting my son to beleive me with his go kart. He just wanted to run the 104, when he went to the 92 pump fuel he went faster. when he went to 89 faster still. Can't get him ti try 87 though. He may be right here but you never know.

Richard

Velocity-8

OK, now lets forget about octane for a moment. Now, I don't know crap about fuels so don't slam me if I'm wrong... :D


So, wouldn't the best situation be to have the best quality fuel and one that has the most "bang" in it? Meaning a fuel that releases the most energy during combustion. I thought from what I've read that using Xylene increases the power of the fuel since it's a purer fuel.

Richard Paul

iTrader: (5)

V-8,
If you really want to play that game nitromethane is the perfect fuel.
As used in dragsters at 90% and 10% methonol it will triple the power over gasoline.

My good friend the late Dave Zeuschel used to say "gasoline is for washing parts, alcohol is for drinking, nitro is for racing."

Anyway most of the gasoline addeditives are anti detonation chemicals. mostly coolants. Nitro can be added to gasoline but it takes a catalist. And you have to be able to change the spark advance and mixture otherwise it will melt EVERYTHING.

I can only say that sticking with the 92 pump fuel is the best thing you can do. Without changing other engine componants you are wasting your money.

Having said that, when you get the supergharger and turbocharger options you might need to look for more octane at high boost levels. Other tricks like water/alcohol injection. Etc.