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Bonneville GXP/ Northstar Powered Cars Discuss your Bonneville GXP and/or any other Northstar powered Olds or Cadillac... Including the 3.5L Twin Cam V6 (Short Star ) 4.0L and 4.6L Northstar V8's. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 01-16-2006, 10:32 PM   #21
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You know I have seen this method described on a couple of Cadillac/Northstar forums they swear that is what helps the motor.

Check hear

Click on Occasional Full throttle accleration is good for your engine.

Just thought you might want to check it out.
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Old 01-16-2006, 10:50 PM   #22
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Originally Posted by willwren
Originally Posted by 1993 SLE
Originally Posted by Jim W
Does anyone agree with my logic or was I blowin smoke?!
I agree with a old ole WOT run to clear out the carbon.....put just leave the trans in D or 3 and go
WOT to clear carbon? Carbon is a by-product of a rich condition. At WOT, most engines run full rich. WOT INTENSIFIES the carbon buildup problem.
Occasional full throttle may be good for it, but you should have a full understanding of the EGR and PCV systems and how they work.

Full throttle is good for your engine in WHAT manner? What are you trying to prevent by WOT? It better not be carbon buildup.
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Old 01-17-2006, 09:15 PM   #23
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Default WOT and Oil usage

I must say, being over here in Germany with my 2004 GXP and now having a little over 18,000 miles on the car, I am consuming less oil than I was before. Not sure if it is because I go at WOT once in awhile on the autobahn or just because the engine is finally breaking in a little bit but whatever it is, I'm glad!

I have been using synthetic oil since the first oil change and I change it according to what the DIC says is left percentage wise. I actually change it with about 15-20% of oil life left. The type of synthetic oil I use depends on what'* on sale. I think that the DIC works pretty well letting you know when it'* time to change. In the summer when I did alot of highway driving, the oil life indicator would go down slower than city driving which makes sense. But I also noticed the oil getting darker in city driving quicker and the oil life indicator reflected that. In other words, driving in stop and go traffic and short distances in the city was reflected on the oil life indicator dropping quicker than highway driving. I will not argue with people who religiously change their oil every 3,000 miles. If it gives you peace of mind and the cost is not a concern then it'* perfectly fine. I just think that if you use the oil life indicator you will not have a problem either. At least I haven't yet.
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Old 01-18-2006, 01:42 PM   #24
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Occasional Full-Throttle Acceleration Is Good For Your Engine (check this discussion for references): (back to the top)

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. It'* designed this way to promote good in-cylinder 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 (wide open throttle) 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 break-in 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 particles, rust and such out of the system.

Frequent WOT operation will not hurt the engine or the transmission. They're 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 transmission shifting out of the question if you are worried about hurting it. 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 - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an 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 over-run 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 over-run 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 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/validated to be run hard. It was expected that people would use the performance of the engine - which few people seem to do. 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 have had, once the owner started doing the WOTs and using the power of 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" at WOT then you are not doing enough WOTs...) etc... A bit of judicious use of the other end of the throttle travel is a GOOD thing...
Interesting read.
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