Proper warm-up for forged pistons

[SoopaCooga]

I'm one of a handful of guys here running forged pistons. You'll recall that forged pistons require greater clearances so that the material can expand when heated. The colder weather has, naturally, increased the time required to warm up the pistons so that they seal. This got me thinking about the "proper" warm-up procedure.

One of the first recommendations I came across was from Corky Bell, author of Maximum Boost, who offered this counter-intuitive advice for Miata owners here:

There are things that can be done to increase forged piston life; driver habits and preparation.

The driver habits are to get the pistons warmed up ASAP. Start motor, move immediately, run modest rpm (say, 3000) max, use moderate boost (2 or 3) if desired, then after water temp needle moves, one good shot of boost will do the warm up job needed. The idea is to reduce the number of engines cycles to warm up.

My views changed when I became aware of the BMW sponsored efforts conducted by Southwest Research...... here in San Antonio, of course. The conclusion was slow warm ups increase wear significantly. How much, I do not know.

What do those of you who have rebuilt engines or own rebuilt engines think about this advice?!? I would like to minimize the time required for warm-up without risking additional wear or "cold-seizure."

 

[svttour]

With or without forged pistons... I usually wait untill the fasten seatbelt light is off to move the car if its cold. Then I fasten my seatbelt.

 

[shavedsvt]

i usually start my car and walk back inside for a few minutes. my car is sluggish if i get in and go. i love my forged pistons tho... no noise from cold starts from the larger clearances

 

[Dyoel182]

I've always heard just to drive it and keep the revs relatively low until it starts coming up to temp. Good advice for all cars really.

 

[SoopaCooga]

I've always heard just to drive it and keep the revs relatively low until it starts coming up to temp. Good advice for all cars really.

That appears to be the best approach, intuitively, and that's what I've been doing.

But that is the opposite of what Corky Bell recommends! I might strike a compromise between the two, which in my mind would be to keep the RPM up around 2-3K, and once both the oil and coolant are up to temp, don't be afraid to boost.

 

[BrApple]

and once both the oil and coolant are up to temp, don't be afraid to boost.

that is what I did over the summer. but then again I would let the car idle and warm up, and I don't have forged internals, at least not yet ....

 

[Dyoel182]

But that is the opposite of what Corky Bell recommends! I might strike a compromise between the two, which in my mind would be to keep the RPM up around 2-3K, and once both the oil and coolant are up to temp, don't be afraid to boost.

Its not really the opposite of what he says. Basically he says drive it easy to warm up and then get it on it a little which is basically what any normal person would do once the car warms up.

 

[SoopaCooga]

that is what I did over the summer. but then again I would let the car idle and warm up, and I don't have forged internals, at least not yet ....

If you are thinking of going that route, buy my Buckshot block and put me out of my misery! :crazy:

 

[SoopaCooga]

Its not really the opposite of what he says. Basically he says drive it easy to warm up and then get it on it a little which is basically what any normal person would do once the car warms up.

In another post he says he gets into boost when reversing out of his garage in the morning! :laugh: