87 octane + T3 turbo

[240Stilo]

Alright now that i got your attention, I'm planning on setting up my turbo kit with a T3 .60 compressor and .63 turbine, FMIC, upgraded injectors, upgraded fuel pump. Basically evrything needed for it to run properly and safely. At what rate will I have to use higher than 87 octane? For example, until 4 psi 87 is safe, until 7 psi 89 is safe, and until 10 psi 91 is safe.

[Yoshi]

well, if you read your owner's manual, KA or SR needs 91 at least. You can technically go down grades until you ping, but why put that to your engine? If you're going to spend all that $ on this stuff, why would you be a stingy azz when it comes to what you feed that nice engine you've built up?

Do it right.

[SilviaDriver]

i agree with Yoshi

but do u know wat the prices are in CA for gas!? 2.11 for 89!! and 91 is the highest we have [for most of us] which runs normally [well here] its 2.31!

but yea..feed wat the engine needs

[240Stilo]

Calm down, just curious as to if you could use this low an octane rating. I remember reading some mag about someone using 87 octance on a turboed car don't remember the specifics but it stuck with me and I was curious about it. Well now that 87 is out the window, until when will the 91 octane offered in Cali be enough?

[Yoshi]

be happy people feel strongly about this, people could just not say anything and let you toast a cylinder :P

Honestly there's no real way to tell you how your engine will react, cuz everyone's is different. Everything is a risk, how willing are you to find out the limits? If you always put in the best, you can rest at ease, mostly.

Honestly, my experience in turbocharging so far, is that there are a BILLION things that can go wrong, and only 1 way to go right... don't screw with your odds, cuz they're not in your favor to begin with, know what I'm saying? :) I wish you luck tho!

[240Stilo]

Originally posted by Yoshi
Honestly, my experience in turbocharging so far, is that there are a BILLION things that can go wrong, and only 1 way to go right... don't screw with your odds, cuz they're not in your favor to begin with, know what I'm saying? :) I wish you luck tho!

You're trying to tell me you don't know.:D I was just thinking that probably in the other guys situation more lower octane fuel was compensating for not enough octane. Thanks anyway I'll just stay away from turboing my car until I'm a little more sure about everything and until I read Maximum Boost by Corky Bell.

[Yoshi]

Originally posted by 240Stilo
You're trying to tell me you don't know.:D I was just thinking that probably in the other guys situation more lower octane fuel was compensating for not enough octane. Thanks anyway I'll just stay away from turboing my car until I'm a little more sure about everything and until I read Maximum Boost by Corky Bell.

Yes and no.
What I'm saying is that I know a guy who's s14 blacktop SR seems to run fine on crappy 87 octane, I know a guy with a redtop who will knock with anything lower than 92. Both setups are completely stock, just different engines, different ages, and different mileage histories. I have a lot of $ in my SR, so hell if I"m going to screw with going down grades of gas until my car gets ****ed; therefore I can't tell you a specific octane range for a specific boost level on a given turbo, not because i'm talking out my a$$, but because there is no clear answer for your question... only recommendations on what is the safest.

Good call on the book tho!

[Jeff240sx]

17 gallon tank. $.20 cents per gallon difference btwn crap and premium. $3.40 for the ease of knowing you'll be safe.
The owners manual states fairly obviously (and on the gas door, mabey the instrument panel) to "Use Premium Gasoline Only." This is because the KA has a fairly advanced timing already. When you turbo the car, you add a lot of heat, and higher octane gasoline will burn cooler, eliminating knocks.
You could run 87 octane on a "properly setup for cheap-ass gas" setup. You'd need to inject more gasoline to run rich, which will cool the combustion chamber. But... by the time you've wasted more gas running richer (and fouling plugs, ect.), you should've probably ponied up the $3.40 for Premium.
-Jeff

[240Stilo]

Well just to clear things up, my gas lid doesn't say to "only use premium." It says "ONLY USE UNLEADED For maximum performance use premium." You might ask now, why wouldn't you want the car running to it's maximum performance level? To that I will answer that with 87 octane gas I notice I seem to be getting better mileage. It may not be true, but I recall a few other people commenting on this as well. But, yes every now and then when I got the extra bills in the wallet I give it premium.

[240Stilo]

I understand basic principles of octane. Too much octane will not be good on an NA engine and too low octane on a high power engine is bad. Things in between would be such as having probably 98 or something to play safely with higher boost. I remember a post way back by boosteds14 about his drive with 21psi I think and 100 octane and I think his result was a thrown bearing. I must have gave the wrong impression with this thread because it sure did start off wrong. I guess what I learned from the most part is you guys can't give me specific info to help me out but you can vaguely tell me how to at least be safer. I will probably be running low boost like 5 psi with 91 octane and move on up from there with some trial and error. Hopefully not too much error with some advise from more experienced people such as boosteds14, like i mentioned earlier, and everyone else on Zilvia.

[DuffMan]

87 will be fine






Just never go above 3000rpms. :D

Actuallly with that small a turbo make it 2700rpms just to be safe.

Seriously though. 87 will cause the ecu to retard timing on a normal engine. That should tell you something right there. When you turbo an engine with an already relatively high compression ratio dentonation is a big issue.

[240Stilo]

Detonation = what exactly? I know it's bad and that's about it. I always pictured it means you blew a hole through something i.e. head gasket or piston.

[DuffMan]

Well here's my oversimplified explanation:

The spark fires before the piston reaches the top, if the explosion is fast enough to reach the piston before it is at the top the compustion is pushing it down while the momentum of the engine is pusing it up.

When you cram more air into a smaller space (turbo or high compression) the air is denser and dense air burns faster. Octane is a componant of gasonline that is a major factor in how fast it burns. With more octane, the gas burns slow which prevents this detonation. Also retarding the timing will prevent it because the spark fires later. Temperature is also a factor in the speed of the combustion.

[240racer]

I equate octane with compression ratio. That means the higher the compression ratio, the higher the octane. If you have a 10:1 cr NA engine, then you beter be running premium. Our engines are 9.6:1, which is pretty close to 10, so that means you should run at least 89. Now you can retard the timing if you want and run 87 with out knock or pinging. Now, if you go and add 5psi to a 9.6:1 cr engine that just bumped it up to 12.87:1 which is definatly in the premium range. Also, you beter be running colder plugs then stock and retarding your timing some. I would recomend this at even 5psi on the stock engine. Those ring lands are really fragile and if not treated properly will just give way. You can make a lot of HP on the engine stock, but it must never detonate. The other thing that you should have is a EGT gauge, that will tell you how hot you are running. It will give a good indicator of when you are getting close to detonation due to heat or running lean (not timing or spark plugs being too hot). For 5psi I would recomend NGK 6 or 7 heat range plugs. If you are going to run more then 10psi then you might want to consider runing colder plugs. Most people are not running more then 10psi on stock internals, and when you get new pistons they are often lower compression then the stock ones, which means you can run a higher boost with the same dynamic compression ratio.

I had problems with my car running 87 octance before the turbo, so I just run 92 all the time now. You can play with the timing and bring it down if you want so you can run 87, but you will make less power. Also, below 3000rpms and about 75% throttle I don't think the octane matters all that much whether you are NA or turbo. With that said it should not affect your gas milage unless you consistantly cruise at full-throttle in 4th or something.

[Jeff240sx]

Originally posted by 240Stilo
Things in between would be such as having probably 98 or something to play safely with higher boost. I remember a post way back by boosteds14 about his drive with 21psi I think and 100 octane and I think his result was a thrown bearing.
I guess what I learned from the most part is you guys can't give me specific info to help me out but you can vaguely tell me how to at least be safer.
Hopefully not too much error with some advise from more experienced people such as boosteds14, like i mentioned earlier, and everyone else on Zilvia.

Wow guy. You're a dick. Everyone who has posted knows a lot about octane evcept you, and your vague comments about everything.
Tell me how fuel, a mixture that only goes into the combustion chamber results in a thrown rod?
No. AFAIK, Boosteds last engine died due to oil starvation, like AceInHole's. Not enough oil in a fast spinning crank/rod assembly, and you now have metal to metal contact, no lubrication, and the parts expand due to heat. The expanded rod and bearing, with thousandths of an inch, will lock up, and stay in one place. The crank forces the seized rod to move, and simply snaps it. Octance does not have the slightest effect on the rods.
Octane affects how fast the A/F mixture burns, and at what temperature. More octane = cooler, detonation resistance mixture. Detonation = combustion cycle of a motor occuring whenever the pressure and heat are great enough to ignite the gasoline, as opposed to a combustion in a controlled, timed location. The result, blown headgaskets, and to a further extent, cracked ring-lands on the piston, and pits on the top of the piston.
There is no error in this thread, as you seem to think, from anyone that has posted, except from you. You need to chill out and read what you say before you piss people off that have helped you.
-Jeff

[pasha]

hahaha.. can you feel the love :)

[240Stilo]

No i didn't ask what knock pinging was I said I didn't know what detonation was, which is my proof people must not be reading my posts well. And 240racer and duff man seem to be the ones who understand what it is I am saying because if Jeff read my statements he would see that I mentioned that I know basic things about octane which therefore lead to letting you guys know the "vague" knowledge that I know so you can fine tune it. Sorry about that wrong info about the result of boosteds14's engine but that's how I remembered it. I thought it sounded weird but I didn't post to ask about it while it was still up. Unless he edited after but like i said, that's how i remember it.

[240Stilo]

Originally posted by Jeff240sx
Tell me how fuel, a mixture that only goes into the combustion chamber results in a thrown rod?

I said thrown bearing, and like i mentioned before that's how I remembered it. Unless a rod and a bearing are the same thing to you.

Originally posted by Jeff240sx
Wow guy. You're a dick. Everyone who has posted knows a lot about octane evcept you, and your vague comments about everything.


Come on now, i tell you the little i know so you know how to help me out and I'm a dick for it. You must be a dick as well for trying to learn new things, according to you're awesome theory that is.

[Jeff240sx]

Spinning a bearing 99% of the time results in a thrown rod.
Also, I for one, am not a dick. If I ask for help, I am very gracious to anyone who offers help.
You, on the other hand, have said that out of the 18 posts, only 2 were correct (Duffmans and 240racer). Then, you said
"I guess what I learned from the most part is you guys can't give me specific info to help me out but you can vaguely tell me how to at least be safer"
and
"Hopefully not too much error with some advise from more experienced people such as boosteds14, like i mentioned earlier..."
Guess what. We gave you specific information, links to other Zilvia topics about octane, and no error.
I dont have an "awesome theory," I have real world experience, mathematical formulas, testimony... what the hell else do you need?
Run higher octane when you make more heat/compression in the combustion chamber.
And a final thing. I don't edit people's post except for offensive language, always make a note in that post, and at the very bottom, it will say:
"Edited by Jeff240sx at 12:12:12 on March 18, 2002" Get over it. I didn't edit anything.
-Jeff

[240Stilo]

Sorry, you are right. I forgot to give thanks to everyone else who is leading me in a good direction, except for you that is. Furthermore, I haven't seen one post that showed a past thread about that octane discussion. I believe i remember that one too; everyone was working out the math to predict the temp of the air in the cylinder and the fuel needed for it to work properly. I say that people have been giving me vague ideas because i get comments such as "every engine is different" such as in yoshi's example with the two SR's. I respect that and I know you guys can't be 100% sure on how a modification would affect my car specifically. And no you're theory isn't a good one because to teach someone it's good to know the little they know so you can take out all the wrong things, reinforce the right things, and build more onto it.

You're right about boosteds14, sorry for not thoroughly reading that thread. You can go ahead and close this sucker if you'd like Ilearned what I had to learn and I'll have to look stuff up the hard way. Thanks again to everyone, except Jeff....well he was right about not thanking everyone and about boosteds14....hmmm that was everything haha.:D

[Tyler Durdan]

You are asking a vaque question looking for a specific answer...the question has to be searching for a specific answer. If you would have said if the intake temp. is x and combustion chamber temp. is y, at what octane should I be running with such boost level and cfm's. That would get you the specific answer you are searching out. There is just way to many factors to calculate...when you give a vague question, it's not possible to get a specific answer. Now, for my vague answer...go here and read about octane ratings and such...Click me (http://www.zilvia.net/f/showthread.php?s=&threadid=19858&highlight=octane) . Just look at it this way, detonation occurs from the combustion chamber temp being too hot and melting the internals, or from the car running lean...which causes the internals to run hot. The higher the octane, the cooler the combustion chamber will be...in turn less chance of detonation. Another way to do it, is to retart the timing to allow the engine to run rich, but you would be wasting that much gas that you saved at the pump, and your idle would be pretty shotty. My suggestion when you go turbo, run a good egt gauge, and premium gas. Look at Sport Compact Car's Turbo Matrix. They turboed the stock 10:1 (maybe higher compression), and drove it from CA to TX and had zero problems. They got the car back six months later from Florida, and had engine problems. They're best guess was that someone had put non premium in on a fill up and caused the enigine problems. If you won't listen to the amateurs (Jeff240sx and others), learn from the pro's. Just run premium for the extra three bucks, and have no worries about detonation being caused by cheap gas.

[240Stilo]

Dangit, it wasn't the thread I was hoping it was. You're right Tyler, my fault for not asking the better question I was wrong to assume that all engines with that type of setup would push out the same temps. Well like I said, I'm off to look for the thread with all the temp and fuel equations to see what I can work out for myself.

[Yoshi]

well, just to add to the chaos, there are other things that no one has yet mentioned taht will alter what you're looking for. Elevation and ambient temperature. Beyond the obvious affects these have, they also can greatly change your A/F mixture, resulting in either a decidedly more rich or more lean condition. I'm fighting this right now as I try to tune my engine by feel, but the weather fluctuates from 20 degrees (3 days ago) to 60 degrees (today).

Tons of variable... so like Tyler said, it's vague answers to a vague question... and not cuz we don't like you, I FULLY understand the learning process, I'm in it waist deep right now, this is just one of those things you'll have to learn by experience... others can lend advice but NO ONE is in the exact same situation to give you difinitive blacks and whites.

Let us know how it goes.

[240Stilo]

Chaos is right, I'm sure i'll let you guys know how my stuff turns out whenever i decide to go shopping for the turbo kit.

[RedlineRacer]

Sorry, I never read the thread about boosted14. How high of an octane did he need to run it safe? I hope no one says "SEARCH".

It's too late at night to think.

[240Stilo]

Boosteds14's thread. (http://www.zilvia.net/f/showthread.php?s=&threadid=14156&highlight=goodbye+KAt)

Just so you know, the octane he was using wasn't the cause of the problem. So, read it well because I sure didn't.

[PowerDrifter]

i agree with Yoshi

but do u know wat the prices are in CA for gas!? 2.11 for 89!! and 91 is the highest we have [for most of us] which runs normally [well here] its 2.31!

but yea..feed wat the engine needs

i just had to bump this because i find it so funny! Damn prices sure have changed

[jr_ss]

i just wanted to increase my post count because i have no useful information to add to this thread!

I fixed that for you. There was no reason to bump a 10yr old thread because you find it funny gas prices have changed...

[PowerDrifter]

I fixed that for you. There was no reason to bump a 10yr old thread because you find it funny gas prices have changed...

hey moron look at my join date and post count. do i look like i give a f&%k about how many post i have? I wouldnt talk compared to you

did i bump an old thread? yes
would you rather me started a new one and everyone yell search? NO!

[jr_ss]

hey moron look at my join date and post count. do i look like i give a f&%k about how many post i have? I wouldnt talk compared to you

did i bump an old thread? yes
would you rather me started a new one and everyone yell search? NO!

Look at my join date and my post count. It's from contributing to this community and being an active part of it.

Your response doesn't make you any less of an idiot.