2.2 KB: Enough octane for the timing?

[SM0KE]

One of my race tunes on my car is for 19#'s of boost w/ 22 degrees of timing on 109 unleaded (that's the fuel used when the car was tuned). I've been around these cars since they've come out and IMO that much octane for that boost/timing level seems like a little bit of overkill. Here's my dilemma: I can get 100 unleaded at the pump approximately 15 minutes from my house. 109 unleaded comes in pales but it's about an hour away from my house. Would 100 unleaded be enough for this boost/octane level? Obviously 109 would be better, but having 100 at the pump is a hell of a lot more convenient. As far as price, 100 is 6.99/gallon and I think the 109 is around 8.99/gallon (can't remember to be exact). I am going to be calling my tuner and running it by him but I figured I'd get some of you guys' opinions as well. If 100 would be putting the car on the jagged edge then I'll stay away from it and just stick w/ the 109. Am I wrong for thinking it's slight overkill to run 109? Anyone w/ experience, your input would be appreciated. :beer:

 

[evil04svtcobra]

why dont you just have a couple different tunes set up for your car?

and when you want the high hp, high boost then run higher timing and octane.

always running 109 would be very expensive.

 

[SM0KE]

This is just ONE of my race tunes. I have a pump gas tune and another race tune besides this one for 23#'s as well. I'm just wondering about this tune.

 

[SM0KE]

ttt...any ideas?

 

[evil04svtcobra]

2 more of my cents... its about octane but also about making sure your getting enough fuel to the engine as well. whats your duty cycle at on these tunes?

i use 93 octane with a bottle of torco... it brings the octane up to around 100 on ten gallons. but im set at 19* of timing on my current tune.

 

[SM0KE]

80% duty cycle.

 

[SVT03Chris]

I'd like to learn a little on this subject too since I see a Race Tune with a 2.2 in my near future :coolman:

 

[Jay Meagher]

I don't see a problem with using 100 with that boost level. If your doing high gear pulls I would want the higher octane fuel, if your doing what 90% of us do it will be fine.

 

[unit213]

IMO...100 octane is fine. I ran an agressive tune on 93 octane for years (19psi / 21* of timing). That was with a 2.2L KB. I run 110 leaded now, but my setup is much different.

Granted, running 19psi and 21* of timing on pump gas is pretty risky and I certainly wouldn't recommend it, but IMO you'll be fine on 100 octane.

 

[SM0KE]

IMO...100 octane is fine. I ran an agressive tune on 93 octane for years (19psi / 21* of timing). That was with a 2.2L KB. I run 110 leaded now, but my setup is much different.

Granted, running 19psi and 21* of timing on pump gas is pretty risky and I certainly wouldn't recommend it, but IMO you'll be fine on 100 octane.

Good to know, thx. Ya, we only have 91 here and it'd be a ticking time bomb running that kind of timing on our junk gas. I went out last night and ran my car thru a few gears and it seemed to run great on 100 Unleaded.

 

[SM0KE]

I don't see a problem with using 100 with that boost level. If your doing high gear pulls I would want the higher octane fuel, if your doing what 90% of us do it will be fine.

Ya, I've never done any 5th/6th gear pulls on my car. I don't think my car's ever seen anything north of 135mph. My IAT2's stay within reason (between 115 and 135 degrees) during a normal pass too, so I'm thinking I should be fine.

 

[04sleeper]

19 PSI and 22* timing is safe with 100 Octane.

Here's a good rule of thumb.

Start with 13 psi and 23* timing on 93 Octane. Pull 1 degree of timing or add 1 point of octane for every PSI of boost you add.

So in this example.

19 PSI - 13 PSI = 6

So @ 19 psi you can either run 17 degrees timing (23-6=17)

Or you can bump up your octane to run more timing.

With 100 octane you would be good for up to 24* timing so 22* will still leave you with 2* saftey margin.

Another thing to note is that the car should run much better with the 100 as well.

The higher the octane the harder to burn.

Hope this helps.

 

[c_mart_28]

19 PSI and 22* timing is safe with 100 Octane.

Here's a good rule of thumb.

Start with 13 psi and 23* timing. Pull 1 degree of timing or add 1 point of octane for every PSI of boost you add.

So in this example.

19 PSI - 13 PSI = 6

So @ 19 psi you can either run 17 degrees timing (23-6=17)

Or you can bump up your octane to run more timing.

With 100 octane you would be good for up to 24* timing so 22* will still leave you with 2* saftey margin.

Another thing to note is that the car should run much better with the 100 as well.

The higher the octane the harder to burn.

Hope this helps.

Awesome info, much appreciated.

One question- what inital octane rating is this general rule of thumb based off of? 91 octane? I'm looking to tune for a little more power myself and am considering going to 19psi with the whipple 2.75 pulley and stock crank pulley or 21 psi with a 3" whipple pulley and 9" crank. If I was to mix torco to create 95 octane shouldn't I be safe running 21 lbs with 17* of timing or 19 psi with 19* of timing? And if that is considered safe, which do you guys think would be the best way to go for power and consistancy?

Thanks in advance,
Casey

 

[04sleeper]

Awesome info, much appreciated.

One question- what inital octane rating is this general rule of thumb based off of? 91 octane? I'm looking to tune for a little more power myself and am considering going to 19psi with the whipple 2.75 pulley and stock crank pulley or 21 psi with a 3" whipple pulley and 9" crank. If I was to mix torco to create 95 octane shouldn't I be safe running 21 lbs with 17* of timing or 19 psi with 19* of timing? And if that is considered safe, which do you guys think would be the best way to go for power and consistancy?

Thanks in advance,
Casey

Sorry, I edited my post. It's based off 93 Octane. For 91 you would have to subtract 2 more degrees or add 2 more points of octane.

If using Torco I would be careful because some of their info is misleading on how much it actually boosts octane ratings.

Here is a good read on an actual test of Torco VS Octane. :read:
Torco Mach Series Accelerator

This can be used as sort of a guidline:

Torco Unleaded when mixed with 93 Octane

.............8oz.....16oz.......24oz.........32oz

5 gal......95.......98..........100...........101
10gal................95..........97.............98
15gal.............................95.............96
20gal.............................................95

 

[c_mart_28]

Okay, cool. Thanks again.

Also, good link posted above. After having visited the torco site it did sound almost too good to be true.

Now I do have potential access to 100 octane leaded aviation fuel which is supposed to check out somewhere around 110 actual octane. I just wish I had unlimited funds, time and material to be able to test these things out individually on a dyno..

 

[SM0KE]

19 PSI and 22* timing is safe with 100 Octane.

Here's a good rule of thumb.

Start with 13 psi and 23* timing on 93 Octane. Pull 1 degree of timing or add 1 point of octane for every PSI of boost you add.

So in this example.

19 PSI - 13 PSI = 6

So @ 19 psi you can either run 17 degrees timing (23-6=17)

Or you can bump up your octane to run more timing.

With 100 octane you would be good for up to 24* timing so 22* will still leave you with 2* saftey margin.

Another thing to note is that the car should run much better with the 100 as well.

The higher the octane the harder to burn.

Hope this helps.

Where did you come up w/ this table/equation? It sounds like it's pretty accurate, so I'm glad you shared it.

However, I just talked to my tuner and he said he wouldn't push 100 octane that far (19psi w/ 22 degrees). So who knows...:shrug: Again, where did you get this info? Thx again man!

 

[04sleeper]

Where did you come up w/ this table/equation? It sounds like it's pretty accurate, so I'm glad you shared it.

However, I just talked to my tuner and he said he wouldn't push 100 octane that far (19psi w/ 22 degrees). So who knows...:shrug: Again, where did you get this info? Thx again man!

From tuners I have dealt with in general. RWTD uses this for their cars as a rule of thumb.

Also a good friend of mine, "Skaarew04SVT" on here, is running 21 psi and 21 degrees timing on his Whipple with Sunoco GT 260 with no problems.

 

[Soundfx007]

You need to understand that octane is made up of two numbers. RON and MON. The 100 you see at the pump is an average. We as hotroders dont give a damn about RON. RON is a low load, low temp, low speed octane. Who cares what your gas octane is when your putting around at 5mph or coasting down a hill with your foot off the gas. We only care about MON (motor octane). FYI, the motor octane of sunoco 100 is 95 octane. Keep this in mind when comparing different fuels. The real deal race fuels like c16 (117 MON) only list motor octane.

But who cares, just buy AV gas 100ll, its 3.50 a gallon and at any airport. I run 25psi and 20 deg of timing in my cobra on straight av gas. As for anyone who starts telling you its for airplanes ignore them. Other than the fact its leaded (bad for 02's and cat's) it works amazing. Ive run it for 15 years in a dozen 10-11 second street cars. The most amazing example of what 100ll can do was in my 650whp evo. At 8700rpm and 35psi boost I raced that car for two years and over 150 passes and never skiped a beat. I even swaped my 100ll out on the dyno once with c16. Only to find av-gas made 5 more hp.