How does higher octane affect turbo?

[Len]

After reading a post concerning mixing some "shadetree" octane additive. I had some Laquer thinner, trans fluid & Desial fuel. So I mixed up a batch . Put in about a quart to a full tank of 93 octane. Drove my car (I listed the mods I just installed on my car in the "I'm telling ya; WOW!!!" Hybridz section). I know higher octane helps avoid detonation. But what else? For example when I usally got on my Z my boost was around 12/13psi. It seems with the higher octane my boost increased to 14/15psi. causing my modified pop off valve to blow. I figure I need to eventually remove the pop off valve since I installed a 1st gen DSM BOV valve. But what other effects does higher octane?

[Drax240z]

Please quit now while you are ahead!

 

"Shadetree" octane additives can be detrimental to your engines health. Be wary.

 

Higher octane will not raise boost levels.

 

A BOV and a POV are not the same thing at all. A BOV does not perform the same function, and by adding a BOV you aren't necessarily replacing the POV.

 

Raising octane simply raises the fuels resistance to burning. This can help prevent detonation and preignition. It isn't going to give you more power (without other modifications), better economy, or anything else. However, if you add laquer thinner, transmission fluid, and diesel fuel to your gasoline, who knows what you are doing.

 

My advice, run the highest octane gas you can find, tune the car for that, and stay away from an unpredictable witches brew. The car will be fast.

[Mudge]

Higher octane means less likely to ping, you can do the math to figure out what your required fuel octane would be.

 

http://www.vtr.org/maintain/gasoline-octane.html

 

I like NA setups, easier to deal with, and often cheaper, but it depends what your going to do with the car. Tolulene was $11 a gallon last I got some.

[Len]

Richard

With referance to "quit while your ahead" Well if I did that then I would still be driving a stock 280ZXT with 7psi. of boost .

"Shadetree octane boosters can be detrimental to engines health". Understood; so is excceding 6000 rpm. If properly researched that xtra 1000rpm (from 6000 to 7000) can really be FUN! .

That's what I'm trying to do ask questions.

"Higher octane levels will not raise boost" That's what I'm trying to find out. WHAT IS THE BENEFIT OF HIGHER OCTANE? I'm searching here guys: Since higher octane levels cause slower burning then retarding timing (which will also help detonation) Will enable a more complete burn causing more power? Also allowing a person to increase boost safely? But still wondering if higher octane would increase boost by itself with no other changes. I remember my stock computer advances and retards timing to a certain extent so that is not a constant.

Concerning BOV and POV NOT being the same thing UNDERSTOOD. Sorry I guess my wording in original post insinuated I was ignorant to the difference between the two. I was thinking out loud concerning next thing I may change on my car. Although I do like the safety of my POV. I guess I'll just add another washer to allow increased boost. Further I like the benefit of my BOV increaseing longevity of my old turbo; wonder why Datsun didn't install one in the first place!

"Higher octane isn't going to give you more power....better economy or anything else" THEN WHAT GOOD IS IT? The post I'm refering to "Shadetree" mix was in Misc. tech section of our HybridZ where bastaad525 and Night_rider_383 really opened my eyes (thanks guys "Anyone heard of using These for boosting octane?". I like it because it sheds light on "higher octane" WITH SUBSTANTUATED research quoting from Richard Lassiters book "How to Mix your own home brew" along with a referance to the Hot Rod Website where people have been using said "Homebrew" for 5 plus years with benefits and no noticable side effects. Its good reading; all of us should read it. Sounds like they know what they are doing.

With all the great knowledge I have gained over the years from this website. I just wanted to hear input concerning my original question "HOW DOES HIGHER OCTANE EFFECT TURBO?"

Oh yea Mudge I see you have been doing your homework. That's basically what I found in Hot Rod website. I was able to purchase laquer thinner cheaper by calling around to paint stores and asking how much to buy before getting a price break. I found I could buy 5 gallons for $16 ($3.20 per gallon) I agree concerning N/A being pretty cut and dry. I'm trying to learn more and more about these turbos.

I guess as with everything. Be open minded enough to absorbe all; then keep what is useful. Discard what is vague and unsubstanuated.

Thanks for input guys

Len

[Mudge]

I know what you mean, playing with a turbo would be FUN, I am guessing though that wanting to road race the car is going to require a nice intercooler $$$

 

So with that in mind, I will probably end up running NA for awhile, and eventually an NA V8, but have to see how it does on the track first, too much power is no bueno in RR, if its more than I can handle.

 

Also, I live in CA, and gas here is crappy (91 octane MTBE), so I'm looking at streetable power overall. I can spend time engine tweaking, or racing, so I figure, lets be practical here...

[Len]

I hear you Mudge. I was born in San Jose and raised in Palo Alto. My mother still lives around Watsonville. Right currently in Oklahoma. gas 93 octane is around $1.25 per gallon. I guess that's another benefit of "Homebrew (although I'm still searching for more information with regards to that). I can only guess what it is in the Bay area (what $1.60?). I was lucky thanks to Shane I bought his NPR I/C for I think around $150 (don't remember I'd slept since then ).

If you read my signature you see I too would also like to install my Lt1 in my 240Z. But first I'm really having a blast working on this 280zxt (while gaining experience and courage!) .

BTW saw a turbo on E-bay last night for around $500 (don't know what it is now). I think it is in Southern CA.

[SleeperZ]

I will attempt to answer your question about octane. A higher octane will resist detonation (uncontrolled burning) more than a lower octane. This will allow you to run your optimum ignition timing for your engine's compression and boost level. That is what can give you more power with higher octane fuel - a Z car generally have a set ignition curve, and if it's set to handle a lower octane without detonation, you will not benefit from higher octane.

 

Search archives here - there are some excellent links on this subject that explain exactly what detonation is and what you can do to mitigate it.

 

By itself, the octane will not "increase boost". That sounds like a function of your boost controller's inability to manage a constant boost level under different load conditions. And be careful with your POV shims. You will add another shim and the valve will be wedged shut, or have so little flow area to be any use. You'd be much better off just plugging it, or adding another or stiffer spring inside so you still have the valve travel.

[Len]

Thanks for the input Nathan!

You are verifying what I was thinking concerning octane and how to; and what to do to benefit from it. I wish I could remember what amount of octane pump gas contained back in 1981/83? To maybe guesstimate what ignition curve z was dialed in at factory to benefit from the highest amount of octane available. So I can figure what would be overkill by using to much octane. I know, I know SDS or what you have (upgraded with a 300zx computer) would be easier but I'm still trying to go farthest with cheapest investment (you know I'm a follower of ScottyMiz ).

Ya, I figured my $35 Dawes booster was creepin! (you get what you pay for). One more reason for keeping POV.

Concerning POV. Thanks for suggestion. I do remember in the 240z site I obtained info. on modding POV in the first place. He talked about a larger spring. Further I didn't think about the possibility of restricting POV flow by using to many washers (which makes alot of sense; I'm currently at three thin ones).

[Mudge]

www.gaspricewatch.com , I'm in 94080.

 

As far as I can recall I payed $1.67 for 87 last I put some gas in the beater, and that is the cheapest place in my area. Premium is $1.87-$2.10 or so in my neck of the woods

 

MTBE is also responsible for as much as 3% power loss, since its a crappy way to raise octane. Supposedly 76 stations dont use MTBE but ethanol, but they are more $ and I dont use premium anymore since I hardly drive the Camaro at all.

[Len]

Mudge

After you mentioned that! dam! I guess "..I'm proud to be an okie from...Oklahoma" (thank you Meral Haggard; sure hope you didn't hear me sing that, that can cause loss of hearing . Now I understand your desire for autocross. Your near my old stomping grounds. I used to drive old La Honda, Skyline Blvd. All over those mountains! (Nearly killed myself more than once during the late sixties!). Agreed;If your "Camaro was an early model those earlier higher compression engines really suffer with crappy gas!

[Mudge]

94 LT1, 411 RWHP @ 5900 RPM (ignition miss ), 11.4:1 compression (shaved and .026" gasket).

 

Skyline Blvd is nice yes, about once a month it seems a biker runs headon into someone and eats it. I have seen some nice Vipers and an occasional Cobra-Replica up there...

[SleeperZ]

Originally posted by Len:

I know, I know SDS or what you have (upgraded with a 300zx computer) would be easier but I'm still trying to go farthest with cheapest investment (you know I'm a follower of ScottyMiz ).

Ya, I figured my $35 Dawes booster was creepin! (you get what you pay for). One more reason for keeping POV.

Concerning POV. Thanks for suggestion. I do remember in the 240z site I obtained info. on modding POV in the first place. He talked about a larger spring. Further I didn't think about the possibility of restricting POV flow by using to many washers (which makes alot of sense; I'm currently at three thin ones).

Truthfully, ScottieMiZ is my hero too.

 

Everything I do is low budget, because I have a low budget. I will be using junkyard injectors and kludging a Z31 MAF sensor into a bigger housing to compensate. With what I have, and the deals on used parts I got, I am seriously thinking 1/4 miles in the mid 12s this spring.

 

I do have a nice boost controller (got a deal on a Greedy Profec B - $100), and it stays where it is set.

 

When I was monkeying around with the POV, I found the spring from a 200SX turbo POV nested inside the 280ZXT POV very nicely, and popped off at 12-13 psi with full valve travel. That double spring can be easily shimmed to 15-16 psi.

[randy 77zt]

when i take my car to thunderhill or other road race track i run union 110 nascar gas.i run about 13 lbs boost.this is cheap engine insurence.its $4 a gallon.the distributor is in my town and can is filled from 20000 gallon storage tank.i usually run 10 gallons on top of a little street gas.no pinging all day.last time at track it was 110 degrees.some day when i get a real turbo engine built i can run the 110 on 20 psi boost.i trash canned the pov valve for a pipe plug from orchard supply.most of the time i run chevron 91 but its 1.80 a gallon.