Just an idle question, but I'm curious as to how much boost you could run on race gas. My friend is a distributor for VP, and he has a lot of C16 at his shop as well as a dyno so that piqued my interest. I'm so used to seeing Supras, 240's doing dynos on C16 with massive amounts of boost. I'm wondering how high you could safely go on a boosted Maxima running race gas. So far all the high hp maximas are running pump right? Matt, Hal, etc.? I know Jim is running a 150 shot on race gas, but I haven't seen any turbo cars using it.

This is all just theoretical of course

 

That is really going to be tough and may even be dependent on the weather around you. I would just start turning up the boost and doing some test runs. If you here knock then take it back a notch and you should be fine.

A friend of mine just did this with his eclipse. He bought a forced performance red turbo (20+ psi) and 880cc injectors along with a DSM uplink and a whole lot more. He got it tuned on regular gas at the shop and the tech who did it said once he put race gas in he could advance the timing and up the boost until it knocks. It was very hot in the shop when he was getting it tuned, once he got some 110 octane gas and cooler weather he was able to turn the boost up from 15psi to 21psi without the slightest worry of knock.

Sorry that I couldn't help more, but I would think if your running high octane race gas on average you could increase at least 5 psi depending on surrounding conditions, but really your just going to have to listen to what your engine tells you.

Free Bump

 

That's what I'm thinking, maybe 5-6 psi difference. The other cars I see dyno there usually up the boost anywhere from 4-6 psi when tuning on race gas.

Luckily he's got the dyno right there so we can do all this on the dyno with a wideband. Hate to do this blind and pop something.

 

Race gas = Less possibility of deteonation ( KNOCK )

So without the worry of it, people rasie the boost bar.

HOWEVER, your still limited due to ALL of the parts of the motor.

Just cause you got 110 octane, does not mean our pistons/heads/etc.. can handle 20 PSI

Hopefully that made sense..

icy will have a better reply when he reads this

 

I don't expect the motor to handle more power just because of the race gas. I just expect that I could get closer to the limit of the motor more safely on race gas. Less detonation just means more safety margin. I wouldn't expect to see more than 15-18 psi safely even on race gas.

 

Good deal

I thought you knew that jeff, just wanted to point it out for safety.


And on 110+ I think 12 PSI would be the limit, but then you have injectors and FMU's to worry about.. unless you already solved that

Let us know what you DYNO

 

Oh, this will be a little while off after I finish some projects. But I was researching some stuff and just got curious about this.

The fuel thing I'm working on also. Hopefully I figure out something that works. High fuel pressure isn't my thing.

We will see on that dyno

 

bags said it well. The main restriction for a stock motor max is internals, not detonation (well, assuming you have that under control)

If your pistons can only hold 14-15psi absolute max, having race gas is not going to make your pistons be able to hold more.

Where race gas shines is if you are limited by detonation/fuel/timing issues. Say your car detonates above 7psi, well, then you could go from 6psi on pump gas to 12psi on race gas...

Make any sense? This is from my little knowledge of race gas, correct me if I am wrong please - I still have more to learn

just be REAL careful and prepared for the worst if you are testing 18psi or whatnot, even if you can get 12:1 a/f at 18psi, that does not mean it will run. at some point I've found its simply too much pressure.

for the record, I run pump gas
(although I may have to use race gas starting next week with the addition of my new toy, only until I get it under control.. )

 

Yo! Shadow....

Are you stuck up now or something????

Saw you driving your girl's car coming out onto 5-forks from the subdivision the other day (the day of the Ms. Parkview pageant) and you looked right at me at the light and even pointed. I flashed my lights at you, but you didn't seem to recognize me. What's up with that????

PSST: I was in the black Lex.....

 

Was this on Saturday? You had the Lex w/ the intercooler right?

I thought it was Sam or Arash's car. Didn't know it was you. I couldn't see inside your car, just saw the intercooler and banner. My bad

BTW, that's where I live now. You live like 2 minutes away right?

 

Just a little info if you guys are interested.

The fuel I use now is by Pro Racing Fuels
http://www.speedwaybikes.com/sponsors/fuel.htm

I use the Mark 5, 114 Octane, but the main claim to fame is that it is unleaded unlike C16 so it won't wreck your sensors. I have a WBO2 Wideband now and it doesn't like leaded either.

Plus it smells great.

 

With race gas, the threshold for Det & Knock are less and change - assuming you are running the same map/tuning that you use on pump gas.

If you have the ability to cnahge your maps, the use of race gas will allow you to use more boost and more aggresive timing.

It will also depend on how much stress your internals and block can take. Assuming you have good tuning and are putting down a lot of power for a long time, fatigue will happen.

On 94 vs 100 octane, I was able to tup my boost +4psi w/o any signs of knock or det.

On 94 vs me on C16, I was able to crank my boost up +7psi.

Then again, I am comparing a flat 4 to a V6. Just trying to give you an idea.

 

When you want to run race gas do you have to completely empty the tank of pump gas first or can you just mix it in? I know jime uses a seperate tank for the race gas but what if you dont have one?

 

Well, I personally run the tank almost dry then I put int he race gas.

If you have a tank with pump gas, then you add some kind of leaded fuel, the octane will be different. Say you have 1/4 of 93, then you stick in a 5 gallon jug of C16, you will not be at a octane rating of 116. There is a conversion to determine the final octane. The amount of each type of fuel you have will factor into the equation as well. I will have to do some digging to get you the math equation.

I have to run at least 100 octane in my car. I usually just run it till the gas light is on and then fill up on the leaded gas.

I also have a drain plug so that makes it easy.

 

Yeah, that was me. Sam has a GS300, but it's not FI'd (yet). I live right off Lake Lucerne. From your subdivision, it's about a block before getting to the lake. You can't see the house from the road, but it's up there.

I just put the CF grille tonight, so it's a little bit different. I can't believe you saw the intercooler. I didn't think it was that visible.

 

It's not that visible, but I kind of look for these things. I saw the Mahdavi banner and took a closer look, saw the wheels and then the intercooler.

 

Man, I live right next to you guys...Old Loganville and Beaver Road

 

That's funny, I do too.

 

HERE YOU ARE MR. I KNOW EVERYTHING:

 

What on earth is you problem?

I made fun of you in one post because you didn't know what you were talking about regarding that subject and now you have beef with me? It's the internet, deal with it. If you don't know something, that's fine, nobody knows everything. It's great to ask questions and learn, that's what we're all here for. But if you post on a topic you don't know anything about and act as if you do, you're going to get corrected. I wasn't the only one who said something.

And then you leave me a weird voicemail about me being too unreliable to install your nitrous when I had absolutely no idea that you wanted me to do it. We spoke of it over AIM, that's about as far as it got, I'm not a mechanic, I help people out if I have time. But I don't recall us setting up an appointment or anything, maybe I just don't remember. Hell, I barely have any time to work on my car. Regardless, just get over whatever problem you have with me or PM me or something. I don't feel like cluttering up the forums anymore.

 

check your PMs

 

I've got 110 right now but I'm trying to get rid of it so I can tune on pump. I put 110 because I was running the haltech and really didn't need the O2 for the ECU.

I was under the impression that you can burn your O2 after running 110 for a bit. Not sure how accurate this is though.

 

just wondering.....
in my recent lean AFR dyno, if I used 100 gas, will I ended up getting a better AFR?

or it is just something wrong with the car because it used to get rich AFR?

thx

 

I've never heard that octane rating has any large effect on afr. The benefit of higher octane is improved knock suppression, so it allows you to run higher boost and/or compression ratio without detonation, as others have already stated.

 

I don't know about burn, but you can ruin the O2's by running LEADED anything. Most 100+ octane gas is leaded gas. There are some that are unleaded, but usually they are lower octane than their leaded counterparts. I have run 104 and 110, but always unleaded. My race track has up to 115 octane but it's leaded. I think that is a similar fuel as they use in airplanes. Not sure though.

Also remember that Leaded gas can damage the fuel injectors too. The orafice of the injectors is very sensitive and can clog.

 

Hmm I didn't know 110 came in unleaded too. The highest unleaded I saw was 104. But yea I meant ruin the O2 with lead. Don't plan on running any of that until I get running right.

So I guess we shouldn't have any issues with a tank of 104/110 Unleaded? 104 should be easy to find at shops, I'll ask about the 110.

 

The fuel I use now is by Pro Racing Fuels
http://www.speedwaybikes.com/sponsors/fuel.htm

I use the Mark 5, 114 Octane, but the main claim to fame is that it is unleaded unlike C16 so it won't wreck your sensors. I have a WBO2 Wideband now and it doesn't like leaded either.

 

Sweet!! so how do they ship that? I didn't think you could order fuel?

 

Not sure how they ship it. I get it locally and they sell it at the track, comes in approx 5 gal steel container.

My supply is almost gone, I have a friend who is sponsored by them so it was free this year. He runs a 11 sec Miata with complete fuel management etc so has to have unleaded for the sensors.

This car started its life as an 18 sec 1/4 mile car.
http://www.etdracing.com/marck.html

 

thx....yea, I should've thought about this too. mine's a fuel delivery issue.....

 

Exactly as Jim mentioned. There are some other manufacturers besides the venerable C16 every track has. C16 is so widely used simply because the cars that use them are usually carburated or have no sensors to worry about. The higher than 104 unleaded fuel is not widely carried at tracks because sensored cars are the minority and therefore they would have a ton of gas going to waste. Remember gas does go "bad", so the track doesn't want it sitting around too long. 104 should be plenty fine for just about any car. Jim is an exception because he is running very close to a ragged edge and therefore needs all the protection against detonation as possible. I would run 150 octane if I was him, if it were available.