My Findings on 87 octaine and FP in an LS1

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Chris B.

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I just finished my 1st tank of 87 octain in my LS1 which requiers "premeium"(91 around here). I also use FP every tank. So far with 87 I hear no knocking/pinging under any type of excelleration/load and no loss in performence that I can tell yet. The engine reves and sound like it did on 91. I hope it stays that way, do you guys think this is safe for this engine?
patriot.gif
 
I'm not going to risk it with my LS1. I don't think that the few pennies saved is worth the risk. I use Fuel Powers as well.
 
Yeah, I'll probibly go back to 91 here soon. I just wanted to see what would happen and it appears to be absolutely no change.
 
I would stick with the 91. Don't save a few $$ and get 87. When I first bought my LS1 the dealership filled it up with 87 octane at their pump. On my 300 mile trip home I could not believe how sluggish the car felt along with the pinging and knocking at low speeds around town. I was doubting the power of the LS1 with my first tank of gas. My first refill went in Chevron 93 octane and it immediately felt like I gained 30rwhp over the 87. BTW I use FP also. I've recently changed my stock heads to Stage II 5.3L heads and I'm now running 10.8-1 compression so I need all the octane I can get.
 
You should definitely stay with the premium gas, because even with 93 or 94 octane a lot of LS1s get knock retard, especially once some carbon builds up.

I used to get audible pinging in my LS1 even when using 94 octane, but it would only happen if the gas was more than a week old. I also had the HPP3 tuning though, along with a timing tricker and a ported stock MAF.

One thing to remember with the LS1 is that if it senses a lot of knock happening over an extended period, it eventually toggles itself over to the "low octane table" in it's programming. Then it stays there until you add at least 5 gallons of fresh fuel. So ideally you want it to remain in the "high octane table" for better performance.
 
Ok even though I hear no pinging I'm going back to 91 which is the highest I have ever seen in Colorado.

Pinging sounds like sparks under the hood, right? My engine sounds normal and just the revving noise can be heard.
 
Chris, because of your operating altitude more than likely the 87 octane and FP is adequate for you (or I would not have recommended trying that regime).

Don't guess ! For anyone trying to drop octane levels using FP keep good records on MPG over a month or two and if able hook up to a scanner and test for injector balance and retard.

If all that works well and the engine develops plenty of power without "clatter" then run it that way because the extra octane is wasted. Right now it will lower your gas bill by 20 % or so too.

If Chris drives down to DO DA Land in Kansas then he would do well to use 91 octane or so.


Terry
 
Thanks Terry! I'll keep with 87 and watch MPG. I don't have access to a scanner though unless the dealer would do but I'm sure theu would charge me a bunch! Anything else I should watch for besides pinging and MPG?
 
I agree with Terry's comment. Ideally, you would want to hook a scanner to see if the 87 octane is causing timing to be pulled. As long as you don't hear any pinging or knocking, then you should be fine. The pinging sounds like ball-bearings in a can.....sort of a machine gun sound....sort of! Knocking is much more audible and easier to identify. Pinging won't cause damage as long as you let off at first sign. Knocking can split a piston if ignored.
 
i'd like to point out that if you can hear the detonation, it's already really bad. there are plenty of cars out there where it isn't audible from the driver's seat.

i used to dyno tune cars for a living. i can't tell you how many people came in saying their car never detonated, and it would ping on the first pull. but, you had to know the trick to hearing it, and my method was near foolproof.

i tuned a lot of supercharged cars especially where people were disappointed with the power level. a few of them then went to another shop where the tuner wasn't as diligent about avoiding detonation and beat my tune in terms of power, only to have their engines breaks pistons within weeks or months.

-michael
 
Michael,
I agree! That's why I wrote "Ideally you would want a scanner" I still believe that with the higher altitudes and "same as before" performance, then he should be ok. The LS1s are notorious for pinging.....and one would be able to hear it right away.
Chris, a scanner is the only way to be sure!
 
LastZ thank for the heads up. Well my rotors are warped so it is going in to be fixed under warranty and I'll ask about the scanner.
 
quote:
Originally posted by Michael SR:
i'd like to point out that if you can hear the detonation, it's already really bad. there are plenty of cars out there where it isn't audible from the driver's seat.

i used to dyno tune cars for a living. i can't tell you how many people came in saying their car never detonated, and it would ping on the first pull. but, you had to know the trick to hearing it, and my method was near foolproof.

i tuned a lot of supercharged cars especially where people were disappointed with the power level. a few of them then went to another shop where the tuner wasn't as diligent about avoiding detonation and beat my tune in terms of power, only to have their engines breaks pistons within weeks or months.

-michael
Click to expand...
Did you ever tune any LT1 cars? I am really happy with the dyno tune I got on mine last weekend. I even got him to tune it based on 91 octane instead of 94, that way it wasn't quite as agressive. He brought the total spark advance curve down to 30 instead of 38 where it was. But even still, we picked up 11rwhp at the peak and found 30 foot pounds of torque in the midrange! The car makes more power everywhere in the curve, even off idle the engine feels considerably stronger. And the a/f ratio is now a much safer 12.5 to 1 instead of the slightly dangerous 14 to 1 (at WOT) He told me he likes to tune for "safe horsepower" and not try to squeeze out 5 more just for bragging rights, only to end up with a motor grenading a week later.

It's amazing what a good dyno tune will do. When I get an LS1 Corvette in a couple of years, first thing I will do is get it dyno tuned. It's an easy way to make the best of something that is already there, it's like free horsepower. The factory never sets them up perfectly.
 
quote:
Originally posted by Chris B.:
How much on average is a dyno tune?
Click to expand...
I paid $320 Canadian, but it would've been $100 less but we needed an extra hour's dyno time when we had to rig up a different intake elbow (we found the stock one was torn)

Most LS1 guys report it cost them about $2-300 US. It's well worth it though. A good tune can easily get you 10rwhp, plus much better driveability.
 
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