LS1 guys: Octane requirements for your LS1Z

[desert dog]

I have been kicking the idea around of the LS1 instead of my planned LR4 in the 240Z, and I was wondering if the LS1 pushing this light car around could sip lower octane fuel than premium without detonating?

[qwik240z]

I hate engine knock. I never tried low octane gas. I always use 93 octane in my LS1 Z.

 

It was recommended by GM for the car it came from so why take chances?

 

If you are building a V8 Z car, don't build it for the fuel it will need to run on.

[LS1 Z]

I agree with David (qwik240z). Use the gas that's recommended for the motor. I WAS having pinging problems at WOT at the track. The problem as too small fuel pump (walbro 190) for the engine mod's I did. Gone to Walbro 255 and switching out the injectors this week for Ford SVO 30 lb (flow 35). Remember on a LS1 or any motor with knock sensors, pinging will retard the timing!

JOEY

[DaleMX]

Well with the 11.1:1 heads I'm running 93 has been ok, no knock. Your stock LS1 is at 10:1 and will run on 87, but the computer will default to the low octane spark table and your power will be gone. Nobody wants that, if you want to use low octane use a SBC with 9:1.

[Mikelly]

...Furthermore, the powerplant knocks down 25-27mpg with the correct transmission. You'll be getting far better MPG than any standard V8 swap. You'll also be able to afford the 93 octane fuel because of that increased mileage.

 

We're guestimating (Based on GMs 15% powerloss claim) that I'm running 430+ at the crank on mine. I regularly see over 30mpg in my 3200# C5 Corvette. A Zcar would certainly see at least the same results.

 

Mike

[desert dog]

Thanks Mike.

 

You have to understand the reason I am asking this question is that I live at high altitude (5300') and the best fuel you can get is 90 octane. There are parts of NM where 88 is the highest.

 

The point of the engine swap is MPG AND HP. This car will be my daily driver. I am thinking that the light loading of 2700 lbs. of the 240Z and the automatic trans that I can run regular for my commute (never go faster than 45 MPH) during the week, and only use premium when I want to go fast. I just don't want low RPM ping in traffic.

 

Off-the-wall question relating to the subject: What is the compressed thickness of the OEM LS1 head gasket?

[Mikelly]

DOn't know off the top of my head what the gasket thickness is. Guess you're shooting for quench numbers?

 

The other thing to think about is that with LS1 edit you can pull out as much timing as you need to, and remap your fuel and spark tables for optimized fuel. I suppose in doing that, you'd be able to tune to fuel availability. I mean, heck, there has to be more than a few C5/6 corvettes and 98-2002 F-bodies running around in your neck of the woods.

 

So it is do-able!

 

Mike

[Phantom]

I have about 18,000 miles n my LS1 / T56 conversion. The car averages 19-20 mpg in combined commuting driving and around 24-25 on the highway at about 70 mph. The aerodynamics of the Z offsets the lighter weight at highway speeds.