E85Forum.com

79superwagon · Joined: 05 Aug 2010 Posts: 1

Hey i have a sbc 350 .60 over high comp. motor i was wanting to know what i need to do to my timing and how much more fuel i will need. ive been running a holley black pump 140 gph 14psi with -10 fuel line. i have a holley 850 getting converted over right now. just wanting to get a heads up to see if i need a new pump or what im running a msd 6al with the probillet disey. mech advance its a solid roller motor the cam is a 310dur.645lift

murphinator · Joined: 08 Jan 2010 Posts: 57

theres a couple e85 carb specialists on here that will answer your carb questions. as for fuel increase on e85 you are looking around 30% increase.

typically you can add a substantial amount of timing but add it in doses and verify you arent getting into detonation
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PB's 1/4 mi 12.209, 117.75 trap ,1/8 mi 7.76 ,93.99 trap , 1.949 short time 4.53 0-60

I tune with HP Tuners software

89shortbox · Joined: 04 Nov 2007 Posts: 135 Location: Michigan

That working all depends on how much power you are making.
Most likely it will work if your under 700hp.

If you where octane limited on gasoline you will be able to add timing. If you werent or you were running race gas you shouldnt need any more timing on e85.
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89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season.

Drag Chevette · Joined: 18 Sep 2007 Posts: 443

Eric68 · Joined: 01 Nov 2007 Posts: 308

You might want to ask your guy doing the conversion what timing curve to run because the tuneup will affect this.

I typically want my carbs run with locked out timing. Depends a little on the application.
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E85 racer and E85 carb builder
www.horsepowerinnovations.com

E85 powered 68 Camaro street car
Best ET on motor 10.04 @ 132 MPH, 5.95 on N2O in the 1/8th

hotrod · Joined: 19 Apr 2005 Posts: 812 Location: Colorado

Timing is effected by your fuel air mixture as richer E85 mixtures burn significantly faster than leaner mixtures (more variation in burn speed with mixture than on gasoline).

That said, start off with the same timing you would run on a 112 - 118 octane gasoline and you should be about right.

Remember that just because the fuel "allows" you to run more ignition advance does not necessarily mean it is a good idea to do so. Over advanced ignition is a primary cause of lots of engine failures, as cylinder pressures go up dramatically with too much advance. The engine runs great right up to the point where it blows a head gasket, burns a valve or kills a bearing due to high cylinder pressures.

You should always run MBT timing in a high performance application. That is the minimum ignition advance that gives you 99% of the max power the engine will make. You tune for best power then back off the timing until you can just detect a slight drop in power (about 1% drop off).

That leaves you a cushion in case your mixture is off, the engine over heats or some other unplanned event causes unusual strain on the engine and cooling system.

The car will make the exact same power if it is over advanced a few degrees, but the peak cylinder pressures and temperatures will be far higher, and your bearings and other components will not live as long as they would with proper MBT timing.

MBT stands for Minimum Best Torque timing.

Larry