Engine Masters - different octane comparison on engine dyno

[kz]

If someone has Motortend on Demand subscription, suggest watching most recent episode of Engine Masters.

They've ran LS3 on engine dyno with 87, 91 pump gas, 110 and 113 race gas and E85 - adjusting timing and AFR for max power/torque.

Results can obviously vary for different engines with different compression rations (and boost), but in this case, every single fuel except E85 resulted in basically same power and torque. Makes these discussions where people swear on running 93 - let's say - interesting. (this applies to Coyote way more than to Ecoboost obviously).

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[Qcman17]

Interesting especially since the LS3 was a 91 octane minimum as per GM. I come from the Camaro side before the GT. I had a L99 auto tuned to run only 94 which was a LS motor as well. Also the LS3 is a pushrod without VVT and while a great motor it is old school to my mind. Its also port injected if that matters or not.

That said I'm really surprised to hear this moreso with this motor say compared to the mighty Coyote.

 

[Schwerin]

I remember someone did similar test on a early 90's v6 Taurus SHO. On 85 and 91 oct the car only had a variance of like 3-4whp and no detectable detonation, but it called for Premium.

 

[kz]

I'm not a GM or LS person but this wasn't stock LS3 - different cam, heads and who knows what else - but not super high compression ratio and obviously N/A. Saw Freiburger post about it on his Instagram account so thought I'd watch. The differences were negligible, on E85 it made about 10 more hp and 10 more lb/ft of torque.

Thought it was interesting to see.

 

[Qcman17]

Yeah not sure how that works. I've always understood more timing is more power and I would normally expect more timing on lower octane plus port injection would be detonation city but who knows? I think it was 10.7:1 or thereabouts iirc.

It's funny I always say I will try 87 and then when I get to the pump it's not today Satan not today

 

[Gregs24]

I'm not sure the results are a surprise. Higher octane rating doesn't increase the energy density of the fuel just the resistance to knock / pre ignition. So total power will not change, but torque availability will improve as you can advance the ignition more before detonation. Think about when old cars used to pink - low revs and sudden wide throttle openings. Before knock sensors, engines were tuned to run on specific fuel octane ratings and would pink (pre ignition) on lower octane fuels. This obviously completely ignores any added detergents etc in premium fuels. As always, pays your money and makes your choice. When 99 is only a few pence more than 95 why not use it, when it is 15 pence a litre more probably not worth it.

E85 no surprise either as it has a lower energy density than standard petrol so will produce less power.

 

[Dr. Norts]

I'm not sure the results are a surprise. Higher octane rating doesn't increase the energy density of the fuel just the resistance to knock / pre ignition. So total power will not change, but torque availability will improve as you can advance the ignition more before detonation. Think about when old cars used to pink - low revs and sudden wide throttle openings. Before knock sensors, engines were tuned to run on specific fuel octane ratings and would pink (pre ignition) on lower octane fuels. This obviously completely ignores any added detergents etc in premium fuels. As always, pays your money and makes your choice. When 99 is only a few pence more than 95 why not use it, when it is 15 pence a litre more probably not worth it.

E85 no surprise either as it has a lower energy density than standard petrol so will produce less power.

I think you mean ping. Cars don't pink.

 

[ice445]

I still want to see someone do this test with low ambient temp versus high ones.

 

[engineermike]

Something most aren't aware of is the dew point has a dramatic effect on octane requirements. If it was humid, then the octane requirement can be as much as 5 numbers lower than dry air. It could explain why they could reach MBT on 87.

 

[v8hgt]

I think you mean ping. Cars don't pink.

Depends where in the world you are from and your age as to what word you use to describe it. The poster is in the U.K. and here the term used to describe the ping/pink sound is generally pinking. Ie a description of the sound. There is no hard G when you hear knock on a British engine. Maybe on an American V8 the knock sound it deeper...

 

[Gregs24]

I think you mean ping. Cars don't pink.

You say tomato we say tomato (OK that doesn't actually work in print !)

 

[Bikeman315]

You say tomato we say tomato (OK that doesn't actually work in print !)

The will help!!

 

[Headless Horseman]

The will help!!

There's a min and a half of my life I can't get back! Can't believe I watched it that long!

 

[Bikeman315]

There's a min and a half of my life I can't get back! Can't believe I watched it that long!

You’re new here Tim. There are many more minutes, hours, days, & weeks to be wasted.

Welcome

 

[JCN]

If someone has Motortend on Demand subscription, suggest watching most recent episode of Engine Masters.

They've ran LS3 on engine dyno with 87, 91 pump gas, 110 and 113 race gas and E85 - adjusting timing and AFR for max power/torque.

Results can obviously vary for different engines with different compression rations (and boost), but in this case, every single fuel except E85 resulted in basically same power and torque. Makes these discussions where people swear on running 93 - let's say - interesting. (this applies to Coyote way more than to Ecoboost obviously).

I had a conversation with the FFRP tech line when I ordered my power pack, one question I had was how would car act on the remote possibility of having to by lower octane fuel in a pinch. He said the computer would still pull the timing to protect itself and that it takes maybe 4 or 5 drive cycles perhaps 2-300 miles for the timing to come all the way back to full setting again. Makes me think that changing fuel and immediately doing dyno pull would be deceiving? could something like this be at play here? can't watch vid so don't know how they went about the fuel changes ect. Jim

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