Roswell256 said:
See here is what I don't get. Everyone opens them up on the road right? What about opening it up sitting in the parking lot in park. That can't be bad on the transmission and other then putting a load on it is equivilent to running it on the road. Correct me if I'm wrong but won't a few redline throttle pumps in the parkinglot do the same?
-Roswell-
Revving the engine up in neutral does little or nothing helpful. The time at WOT is so brief that there is little or no chance to build any cylinder pressure and heat before the engine is bouncing off the rev limiter. Revving it at part throttle puts little or no gas pressure load on the engine and pistons - it puts a lot of inertial loads into the crank, bearings, rods, etcetera - but nothing that does any good to the engine. Forget it. Put the car in gear and go drive it.
There are many advantages to occasional full throttle accelerations with a Northstar and any engine. It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. This is designed this way to promote good incylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build up to touch the piston causing noise. Ever heard of the Northstar "cold carbon rap" problem? Simply put you'll hear a rythmic, piston slap like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head causing it to rock in the bore and "slap" - much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.
Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston. They actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant. Also harder to breakin and seat the rings to the sides of the ring lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related to some extent with the rings never seating to the sides of the ring grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring grooves due to carbon build up can eventually be freed up with enough high RPM operation.
WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particulates, rust and such out of the system.
Frequent WOT operation will not hurt the engine or the transmission. It's designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing. No carbon buildup.
The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the trans shifting out of the question if you are worried about hurting the transmission, also. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point ie 6500rpm for an L37 and 6000rpm for an LD8. Hold the throttle wide open until the engine reaches, say, 6200rpm for your STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy overrun conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy overrun which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of the cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.
The Northstar engine was designed, developed and validated to be run hard. It was expected that people would use the performance of the engine, though few seem to do so. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.
In every conversation with owners I've had, once the owner started doing the WOTs and using the power and the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" when you do a wot you are not doing enough WOTs) etcetera. A bit of judicious use of the other end of the throttle travel is a
good thing.