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| iCorvette | how much warm up do forged pistons really need? | ||
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Senior Guru
 
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or is this a myth?
i can't sit all the time to warm the car, every other car I've had i just start and go...like anyone else on earth, why don't their engines blow up? now with this "hi performance engine" i have to wait for the water temps, oil temps, forge pistons, valve springs to warm up, jeez, and the darn thing is so cold blooded and takes forever to even get to 160* water.. any good advice??? please don't say buy a mustang or something like that.... |
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Posted on: 2009/8/2 2:37
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| Durango_Boy | Re: how much warm up do forged pistons really need? | ||
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Elite Guru
 
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From what I've experienced you can start it and drive immediately, but don't drive aggressively before it's warmed up a bit. The pistons will warm up faster than the water, same with the valves, so don't think of it as an engine temp thing.
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Posted on: 2009/8/2 2:58
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| Churchkey | Re: how much warm up do forged pistons really need? | ||
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Depends on piston to wall clearance. .004 or more clearance & you can hear the pistons slap on cold start up. If this is the case its a good idea to let the engine run a bit to get some heat in the pistons before driving.
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Posted on: 2009/8/2 11:06
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| Stl94LT1 | Re: how much warm up do forged pistons really need? | ||
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Guru Newb
 
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I agree!! But, before I run the car hard I wait for 160* oil temps which are more important that the coolant temps at the point. |
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Posted on: 2009/8/2 17:14
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| iCorvette | Re: how much warm up do forged pistons really need? | ||
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Senior Guru
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Quote:
yeah it takes quite a while for the oil temp to register on my atari dash, when the water goes to 175-180 then the oil pops up( blank before this number) at 150, i've hammered it at 150*, i assume 160 and 150 are close, depending on the viscosity of the oil right?, i think it have 10-30 in there not 10-40 so do you think the 10* differential is immaterial? sometimes coming home from a club, and trying to warm the car, it is not even 150 degrees on the oil when i get on the freeway,....... so is it cool to drive the car at 75-80 mph when the engine oil is cold like that? i do rev it slow to get to speed, but i don't floor it yo know what i mean right? thanks for the comments! |
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Posted on: 2009/8/2 18:18
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| BillH | Re: how much warm up do forged pistons really need? | ||
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The Stig Moderator
 
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150s fine to cruise up the freeway as long as you don't totally hammer it. Churchkey's right about the piston to wall clearence making some difference. And the tighter the clearance, the more you need to warm things up. Aluminum expands faster than the steel bore. My LT1's stock, I warm it to 100/water and drive easy, shift under 2500 until it gets warmed up. On a warmer day, you need to get to 150/w to see 100 on the oil. Crusing easy won't hurt anything, you're not really loading the motor. In the racecar, it's 200 oil temp before I move the car. On the vintage Nascars, with the tight clearences, we heat the oil to 140 before starting. We also pull the pump belt and spin the pump with a drill to get 100 psi. oil. Then start and don't rev the motor at all until 200/oil and 180/w. |
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Posted on: 2009/8/2 19:44
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| CentralCoaster | Re: how much warm up do forged pistons really need? | ||
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"Warming up" basically any engine is unnecessary. Just start it and drive.
Once the oil is circulating, there's no need to sit there and idle, it just causes more wear on the engine, not less. My definition of warming it up is to let the oil temp start registering before I lay any rubber down. |
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Posted on: 2009/8/2 19:50
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| BillH | Re: how much warm up do forged pistons really need? | ||
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The Stig Moderator
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CC, I respectfully disagree. |
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Posted on: 2009/8/2 19:53
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| dan0617 | Re: how much warm up do forged pistons really need? | ||
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I don't warm up for very long at all, but this is a little aggressive even for me! When I first fire the car I let it warm up for about 30 seconds. I drive normal till it gets to about 160 water, then I am not afraid to hammer on it. I have forged pistons too. |
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Posted on: 2009/8/2 20:34
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| iCorvette | Re: how much warm up do forged pistons really need? | ||
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how many miles on your engine? do you use synthetic? |
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Posted on: 2009/8/2 20:58
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| bogus | Re: how much warm up do forged pistons really need? | ||
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Grand Imperial Pooh-Bah
 
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I only ever warm up when I lived in winter.
And even then, it was only on extreem days and only because I am a wuss and wanted heat in the car.  At that stage, I would shower, eat breakfast, run out and start the car, then come back in, change and brush and then leave... it idled no more than 5-7 minutes. And this was only 5-10 days a year, tops. The rest of the time, start the car, as I buckled and changed to my sunglasses, I would leave. 20-30 seconds to let the oil pump up. Easy. |
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Posted on: 2009/8/2 21:26
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| Durango_Boy | Re: how much warm up do forged pistons really need? | ||
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The rest of the time, start the car, as I buckled and changed to my sunglasses, I would leave. 20-30 seconds to let the oil pump up. Easy. Curious, why it takes you 30 seconds to put on a seat belt and sun glasses. LOL. 1...2...3...4...5...6...7...8...9...10...11...12...13...14...15...16...17...18...19...20...21...22...23...24...25...26...27...28...29...Ready to drive, LOL. |
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Posted on: 2009/8/2 22:04
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| BillH | Re: how much warm up do forged pistons really need? | ||
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The Stig Moderator
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6 point harness and having to get the glasses past your ears with a helmit on????????????? |
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Posted on: 2009/8/2 22:06
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| anesthes | Re: how much warm up do forged pistons really need? | ||
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Master Guru
 
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Obviously few of you build engines.
Cast pistons have the tightest wall clearance, because they expand less than forged. OEM uses them because they are cheap, and can be fitted with a tighter clearance and won't rattle when cold. Forged pistons expand when they heat up, which depends on how much silicone alloy is mixed in. The manufacturer will specify what the wall clearance, and you measure this when performing the final hone to fit the pistons correctly. When a piston has too much wall clearance, it can rock. Most heads position the plug so that the combustion will take place more toward the exhaust valve. Hammering a cold motor with too much piston to wall clearance causes the skirts to break off the piston and fall into the oil pan. -- Joe |
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Posted on: 2009/8/2 22:20
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| iCorvette | Re: how much warm up do forged pistons really need? | ||
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Senior Guru
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no problem, is seeing 100 on the water good enuff? |
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Posted on: 2009/8/2 23:07
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| anesthes | Re: how much warm up do forged pistons really need? | ||
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Master Guru
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To drive or go racing? Depends on the application. Track only cars run different sidewall clearance than street cars. Call the manufacturer and ask them. They will probably tell you to wait until the thermostat opens at least once, because that saves them from liability if you blow up your motor. Well not really blow up. I've taken apart motors with piston skirts in the pan and nobody noticed. Ignorance is bliss. -- Joe |
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Posted on: 2009/8/3 2:24
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| dan0617 | Re: how much warm up do forged pistons really need? | ||
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Senior Guru
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That is what I do when starting and driving the car when it is cold out, like below 50 degrees. I'm sure the small warm-up time helps the trans some too. iCorvette, my motor has about 1500 miles on it, and I do now use synthetic oil. Easiest way to figure it out, if you want to know exactly. Go pull everything off your valve covers. Plug all the holes but one. Start the car when cold. Notice how much blow-by there is. You will be able to see smoke drifting out the valve cover hole that you didn't plug and will feel it blowing a little with your hand. You will be surprised at how much blow-by there is on a cold engine with forged pistons. Let the car warm up, walking back and forth so you can keep an eye on the water temp (or oil temp if you prefer, that would be better) and the blow-by. You will notice the blow-by lessening as the car warms up. When the blow-by has quit getting less, see what the gauge says. Figure a few extra degrees, and now you know what temp your pistons have expanded fully and you are ready to go hammer on it. |
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Posted on: 2009/8/3 12:23
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| iCorvette | Re: how much warm up do forged pistons really need? | ||
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Senior Guru
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Thanks! I have about the same miles on my engine.. can you comment at around what range temps these pistons need to expand properly? this way i can have an idea before i do that test you suggested... and when did you go synthetic? |
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Posted on: 2009/8/3 15:51
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| iCorvette | Re: how much warm up do forged pistons really need? | ||
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open at least once it it's lifetime or in a day? |
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Posted on: 2009/8/3 15:52
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| dan0617 | Re: how much warm up do forged pistons really need? | ||
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I went synthetic after about 300 miles.
I haven't done that test myself on this engine as I don't worry that much about it. |
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Posted on: 2009/8/3 15:53
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| CentralCoaster | Re: how much warm up do forged pistons really need? | ||
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Why? Are you driving a vintage Nascar to work in the morning? |
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Posted on: 2009/8/3 17:57
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| GRX | Re: how much warm up do forged pistons really need? | ||
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Just to note that 1984-85 vettes came with forged pistons from the factory. I have forged TRW slugs in mine and warm up only because I'm running a supercharger setup. Never hear any piston slap.
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Posted on: 2009/8/5 4:13
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