When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The ecm will not experiment with timing advance if running more than 93 octane. Higher octane in an engine engineered for 91 is a waste of time and effort, been proven over and over for decades. Can't get something for nothing.
When you say engineered for 91, are you saying all air quality and fuel is equal? There are lots of variables and it’s safe in the extremes because of its ability to retard timing, but that doesn’t mean higher octane can’t be beneficial in certain conditions. The tests I’ve seen done that you speak of were on older engines that didn’t have variable valve events that vary the dynamic compression ratio as static compression you mentioned isn’t the only factor in determining the octane requirement. A tune can be set up for best case scenarios, i.e. the 100 octane “tune” in the previous generation Corvette.
When you say engineered for 91, are you saying all air quality and fuel is equal? There are lots of variables and it’s safe in the extremes because of its ability to retard timing, but that doesn’t mean higher octane can’t be beneficial in certain conditions. The tests I’ve seen done that you speak of were on older engines that didn’t have variable valve events that vary the dynamic compression ratio as static compression you mentioned isn’t the only factor in determining the octane requirement. A tune can be set up for best case scenarios, i.e. the 100 octane “tune” in the previous generation Corvette.
11.5 compression ratio is set in stone unless boosted. Let's see some real ENGINE dyno numbers.
Not drag time crap.
I know what an acronym is, and those don't qualify.
So what do they stand for and curious your experience tuning engines? As you demand a lot, but don’t offer much. How about the “initialism” IVC, does it have anything to do with cylinder pressure and if you change the IVC does it change the “boost”?
My CA car with 91/E85 blended to about 95 octane seems to be happy. We don't have any Kum and goes here in CA. They are called something else and they don't sell gas. I remember a few years ago while travelling for work I seen one of these stations and about lost my ****. I had to send all my buddies a picture. The kid in me couldnt get over that name. I walked in and was disappointed.
Wonderful. Do you know how timing advance works? This isn't the 1950s with a stationary cap & rotor.
Yeah, but my first hotrod had a points distributor with 12:1 SCR and I realized the amount of timing I could run was weather dependent. I also could tell the difference when adjusting lash on the rockers, which slightly changes the valve events
Yeah, but my first hotrod had a points distributor with 12:1 SCR and I realized the amount of timing I could run was weather dependent. I also could tell the difference when adjusting lash on the rockers, which slightly changes the valve events
Clearly your hotrod wasn't "engineered" for 91-octane
Clearly your hotrod wasn't "engineered" for 91-octane
Haha, no fortunately we have 93 here though usually mixed octane booster in it when not running 100LL. Back to the LT2, viscosity of the oil varies with temperature and doesn’t that affect the cam phaser?
Some Sunoco stations around here have 94 octane premium, anyone ever run it in their C8?
I have. The locations along Dallas North Tollway have it so I've stopped at the Plano station a few times since its only a few exits south of my office.
Haha, no fortunately we have 93 here though usually mixed octane booster in it when not running 100LL. Back to the LT2, viscosity of the oil varies with temperature and doesn’t that affect the cam phaser?
I believe an oil pressure solenoid is used to adjust the cam timing, at least in the Hondas and Mitsubishis I've torn apart. I'd assume GM's technology isn't wildly different...
All I'm saying is the fact that a LT2 is still a basic small block, you can change fuel timing and volume, you can change cam timing although you can't change cam LSA, you can change spark timing, but you can't change the maximum combustion chamber size or compression ratio..
Bang for the buck is dismal on a naturally aspirated engine with ethanol. Your better off doing Nitrous with your money.
If anybody has any hard data from a LT2 on an engine dyno I would love to see it.
@Kracka I am not going to get into all this Engineering marvel you ding dongs are talking about. I have always said "If you dont have anything valuable to offer STFU" LOL With that said. Here is the bottom line for me. I live in Northern Ca and luckily I have a E85 "Marathon" station down the street. It ironically is the cheapest gas with 4 stations at all 4 corners. These are rough numbers and it continually changes but E85 is roughly $3.29 and 91 $4.89. I mix 4 gallons of E85 to roughly 13-15 gallons of 91. Last tank in my Camaro that makes 750HP went 4/14 gallons. I ran that pig dry. With the worksheet that gave me about 94 octane. Car loves it. I do the same with my C8 which just has bolt ons. Both cars drive just fine. When I put a little to much E85 in the car I get a CEL but it goes away. It has been a trail and error.
Now with that said here is my EXPERT opinion. Other then saving a few bucks I dont see no difference. I am sure its there but I drive the dog **** out of both of these cars and they perform well. In my non expert opinion, if E85 burns hotter and cleaner, I am doing the cars a good thing while saving a buck. And as mentioned yes MPG are affected so am I really saving
As for that "Kun and Go" merch, next time you stop grab me a large tee shirt. You have my address I will Zelle you the cash. You know I am good for it. LOL
All I'm saying is the fact that a LT2 is still a basic small block, you can change fuel timing and volume, you can change cam timing although you can't change cam LSA, you can change spark timing, but you can't change the maximum combustion chamber size or compression ratio..
Bang for the buck is dismal on a naturally aspirated engine with ethanol. Your better off doing Nitrous with your money.
If anybody has any hard data from a LT2 on an engine dyno I would love to see it.
Electronic fuel injection has been around for a long time of course, but they’re pushing the limits on detonation for the sake of emissions. To say the computer can handle whatever is thrown at it perfectly is like saying every situation can be accounted for with autonomous vehicles. Also race teams tune an engine for the current conditions if they’re serious about maximizing performance. Instead of a dyno number, I’d say log KR with and without to see if the corn supplement helps or not and don’t just look at peak WOT for gains.
@Kracka I am not going to get into all this Engineering marvel you ding dongs are talking about. I have always said "If you dont have anything valuable to offer STFU" LOL With that said. Here is the bottom line for me. I live in Northern Ca and luckily I have a E85 "Marathon" station down the street. It ironically is the cheapest gas with 4 stations at all 4 corners. These are rough numbers and it continually changes but E85 is roughly $3.29 and 91 $4.89. I mix 4 gallons of E85 to roughly 13-15 gallons of 91. Last tank in my Camaro that makes 750HP went 4/14 gallons. I ran that pig dry. With the worksheet that gave me about 94 octane. Car loves it. I do the same with my C8 which just has bolt ons. Both cars drive just fine. When I put a little to much E85 in the car I get a CEL but it goes away. It has been a trail and error.
Now with that said here is my EXPERT opinion. Other than saving a few bucks I dont see no difference. I am sure it’s there but I drive the dog **** out of both of these cars and they perform well. In my non expert opinion, if E85 burns hotter and cleaner, I am doing the cars a good thing while saving a buck. And as mentioned yes MPG are affected so am I really saving
The CEL comes on because you’re outside of the parameters that the tune can compensate for and are running lean correct?
. I remember a few years ago while travelling for work I seen one of these stations and about lost my ****. I had to send all my buddies a picture. The kid in me couldnt get over that name. I walked in and was disappointed. 
