Engine break in. How do you tune without having miles on it?
06-30-2011, 08:15 AM
#1
Engine break in. How do you tune without having miles on it? Forgive my ignorance here, but I know nothing about tuning. And yes, I searched, but only found one relevant thread that didn't really have an answer.
My short block is currently getting rebuilt as a stock "refresh" job. Polished crank journal, new bearings, new pistons, etc.
But I'm planning on a heads/cam combo, which the stock tune obviously won't work too well.
Before you dyno tune it, I'm assuming you need to break it in. But how do you break it in if you don't have it tuned? Do you just get some "guesstimate" tune work done to allow some miles on it first?
Or do you just run the stock tune until its ready to dyno? I'm worried that an improper tune may cause damage to the engine.
I'm also pretty certain you just can't throw a fresh rebuild on the dyno either.
What does everyone do?
Thanks!!
My short block is currently getting rebuilt as a stock "refresh" job. Polished crank journal, new bearings, new pistons, etc.
But I'm planning on a heads/cam combo, which the stock tune obviously won't work too well.
Before you dyno tune it, I'm assuming you need to break it in. But how do you break it in if you don't have it tuned? Do you just get some "guesstimate" tune work done to allow some miles on it first?
Or do you just run the stock tune until its ready to dyno? I'm worried that an improper tune may cause damage to the engine.
I'm also pretty certain you just can't throw a fresh rebuild on the dyno either.
What does everyone do?
Thanks!!
06-30-2011, 06:01 PM
#5
I'm not crazy about breaking in a motor with no scanner hooked up to it. Ideally, you would want the tune to be pretty close, fuel wise, and timing. Then you'd start it and run it briefly, to check for leaks. Get it up to operating temp, make sure you have no air pockets in the cooling system, then run it and tune WHILE breaking it in.
06-30-2011, 06:14 PM
#6
I'm not crazy about breaking in a motor with no scanner hooked up to it. Ideally, you would want the tune to be pretty close, fuel wise, and timing. Then you'd start it and run it briefly, to check for leaks. Get it up to operating temp, make sure you have no air pockets in the cooling system, then run it and tune WHILE breaking it in.
06-30-2011, 11:00 PM
#7
I'm not crazy about breaking in a motor with no scanner hooked up to it. Ideally, you would want the tune to be pretty close, fuel wise, and timing. Then you'd start it and run it briefly, to check for leaks. Get it up to operating temp, make sure you have no air pockets in the cooling system, then run it and tune WHILE breaking it in.
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07-01-2011, 07:31 AM
#8
Launching!
If you're smart about the tuning process, it shouldn't be bad for break-in at all. I usually tune part throttle and light loads first. This puts the engine at slightly elevated speeds and under vacuum, which exactly where most engine builders like having their rings and cams broken in at. Doing this will get most of the ring seal done in about 15-20 minutes (or less) once everything is up to temp.
The other nice thing is that engines "want to run" at part throttle and are far less likely to load up and stall than they are at idle, or far less likely to break from stress like they would be at WOT. This gives the tuner a good opportunity to learn a lot about the new VE surface that goes along with the new heads/cam/intake/exhaust/displacement/whatever without putting the engine at much risk. It also lets the tuner slide through many of the cells in the MAF table in steady state so that he can get a good idea of what the curve should look like if he's dealing with a new MAF placement, cold air kit, or new physical sensor. A lot of what you learn about engine performance at part throttle can be carried down to idle and up to WOT after the engine is more broken in.
The other nice thing is that engines "want to run" at part throttle and are far less likely to load up and stall than they are at idle, or far less likely to break from stress like they would be at WOT. This gives the tuner a good opportunity to learn a lot about the new VE surface that goes along with the new heads/cam/intake/exhaust/displacement/whatever without putting the engine at much risk. It also lets the tuner slide through many of the cells in the MAF table in steady state so that he can get a good idea of what the curve should look like if he's dealing with a new MAF placement, cold air kit, or new physical sensor. A lot of what you learn about engine performance at part throttle can be carried down to idle and up to WOT after the engine is more broken in.
