MFI and Techron

daepp · daepp's Garage

Are fuel injector additives like Techron recommended for the MFI cars? Has anyone actually used it? If so, at what frequency? Concentration as per the instructions on the bottle?

kwikt 911 · kwikt 911's Garage

Don't know if it really works but I use the Techron injector cleaner in my 72 with mfi. It seems to run a little smoother when added.

Kevin

pwd72s · 06-16-2008, 08:37 AM

Can't hurt, might help. But do keep in mind that MFI operates at a much higher pressure than later fuel injection systems. This makes the injectors semi self cleaning. But then, there is the additional carbon removing benefits that fuel system cleaner additives tout...

Jeff Higgins · 06-16-2008, 10:30 AM

I don't run Techron, but I do run Marvel Mystery Oil. I'm more worried about pump piston lubrication than injector cleaning; as Paul points out, the very high nozzle pressure keeps the injectors themselves pretty clean.

My reasoning behind the Marvel Mystery Oil is that these pumps originally ran on leaded gas. Lead has lubricating qualities essential to early, non-hardened valve seat life. Removing the lead led to many early valve seat failures in cars designed to run with lead; modern stellite seats fixed that problem. Nothing has been done with the pistons in our pumps.

I'm not sure that the pistons in our pumps really need much lubrication. They do, however, only "see" gasoline, which now has no lubricating qualities whatsoever. Are the pistons loose enough to allow the motor oil to migrate all the way up the cylinder walls? Seems if they were, there would be a great deal of gasoline "blow by" into the pump (even when new), since the gasoline side generates such high pressure - 230 psi. Did the Bosch engineers count on the lubricating qualities of lead to lubricate these pistons? It's probably well neigh impossible to find out at this point. What I do know, for sure, is that they ain't making any more. I'm playing it safe with the ones I have and adding a bit of lube into my gasoline.

RSBob · RSBob's Garage

Jeff,

How much do your add and how often? Also is your engine back together?

Thanks,

Rick

304065 · 06-16-2008, 12:05 PM

Quote:

Originally Posted by Jeff Higgins

I don't run Techron, but I do run Marvel Mystery Oil. I'm more worried about pump piston lubrication than injector cleaning; as Paul points out, the very high nozzle pressure keeps the injectors themselves pretty clean.

My reasoning behind the Marvel Mystery Oil is that these pumps originally ran on leaded gas. Lead has lubricating qualities essential to early, non-hardened valve seat life. Removing the lead led to many early valve seat failures in cars designed to run with lead; modern stellite seats fixed that problem. Nothing has been done with the pistons in our pumps.

I'm not sure that the pistons in our pumps really need much lubrication. They do, however, only "see" gasoline, which now has no lubricating qualities whatsoever. Are the pistons loose enough to allow the motor oil to migrate all the way up the cylinder walls? Seems if they were, there would be a great deal of gasoline "blow by" into the pump (even when new), since the gasoline side generates such high pressure - 230 psi. Did the Bosch engineers count on the lubricating qualities of lead to lubricate these pistons? It's probably well neigh impossible to find out at this point. What I do know, for sure, is that they ain't making any more. I'm playing it safe with the ones I have and adding a bit of lube into my gasoline.

Oil has an octane rating of ZERO. Remember that when you mix, particularly after the meltdown repairs (although twin plugs should help)

Jeff Higgins · 06-16-2008, 12:34 PM

Quote:

Originally Posted by RSBob

Jeff,

How much do your add and how often? Also is your engine back together?

Thanks,

Rick

Whatever the bottle says; I want to say it is about 3-4 ounces per tank. And yes, it is back together and running great.

Quote:

Originally Posted by john_cramer

Oil has an octane rating of ZERO. Remember that when you mix, particularly after the meltdown repairs (although twin plugs should help)

Yup, you are right. I'm thinking that a few ounces in 15-18 gallons does not significantly affect octance rating, however. I wonder if there is any information available on how much it does, if it's even measurable.

304065 · 06-16-2008, 01:05 PM

Quote:

Originally Posted by Jeff Higgins

Yup, you are right. I'm thinking that a few ounces in 15-18 gallons does not significantly affect octance rating, however. I wonder if there is any information available on how much it does, if it's even measurable.

I think in Bruce's book there's a mixing chart showing the octane effect of 100LL avgas with premium. . . I would see if you can figure out the formula used there (it may be a simple weighted average) and then substitute ZERO and the mixed quantity to see how much it comes down.

IF it's a true weighted average. . . MMO recommendation of 4oz to 10 gallons of 93 pump fuel . . . going metric, that's

0.118294118 liters of MMO to

37.8541178 liters of 93 octane R+M/2 fuel (or 35.204330 of 100% iso-octane and 2.649788 heptane)

since the MMO has zero octane, you just add the quantity of MMO to the heptane number. . . now 2.768082 liters of heptane equivalent, plus the original 35.204330 liters of 100 equivalent- gives you 37.972412 liters in total. Now divide the hundred equivalent by the total . . .and you get. . . . . .

. . . 92.7 octane. . .

So much for math!

(before some gasoline pundit starts pencil-whipping me, I KNOW that gasoline doesn't actually contain heptane and iso-octane in those proportions, it's just an index AS THOUGH it did.)

Jeff Higgins · 06-16-2008, 01:09 PM

Darn, John, I missed the obvious. Of course it boils down to simple math, knowing the octane rating of Marvel Mystery Oil - zero. Somehow, I was getting confused with products intended to alter octane, which this stuff most decidedly is not.

pwd72s · 06-16-2008, 01:15 PM

Quote:

Originally Posted by Jeff Higgins

Darn, John, I missed the obvious. Of course it boils down to simple math, knowing the octane rating of Marvel Mystery Oil - zero. Somehow, I was getting confused with products intended to alter octane, which this stuff most decidedly is not.

But MMO might help lube the MFI pump's pistons...I used MMO too. Now that Oregon requires 10% alcohol in all automotive gas? May be even more beneficial.

Lucky for my old car that it now lives in a country where leaded gas is available...
her MFI pistons back to being lubed as designed.