Increased Idle Engine Noise/vibration with Forged Internals?

[ddogg777]

I am sending my pistons to swain tech to have the thermal bariar coating and skirt coating anyone else interested let me know pm me or something...

Mine will be there with ya! Have you also looked at Hpcoatings? They have better prices...

YP5, Did you get your rotating assembly balanced? I can't understand why your pistons could be making so much noise because they are OEM material (methinks). But if something is slightly out of balance, you will notice when it hits the right rpm. Just like a tire that causes your car to shake at 63-66mph; it hits that spot where resonant frequency rears its ugly head!

 

[MPNick]

Nick...come on.... thats not a very informative post....

Seriously...why is it not always a good idea?

When you coat the top of the piston you now have more heat the stays in the combustion chamber. Without the coating the heat will tranfer from the top of the piston down to the skirts and then to the cylinder walls and then to the cooling system. Your piston will expand faster and you reduce the amount of time that you have piston slap. Also now that you keep more heat in the chamber you need to reduce the amount of spark timing then before. With the extra heat you can detonate sooner. You also should run more end gap in your top piston ring. The temps on the top of the pistons will be higher so the top ring will grow more.

There are two side to the debate on coating the top of the pistons. Some OEMs have it stock, they have made the changes that was needed to run the coatings. I know alot of the very fast import racers use them but they also run alcohol fuel. This fuel burns alot cooler then pump gas so they do not have the same problem. Some people say that with top coatings you have less of a detonation because the heat across the piston top is closer to even that without. I have tried them and it does work with race fuels. I have not seen a gain with pump fuel. You mileage may very.


Thanks again


Later.................Nick

 

[YP5 Toronto]

Hmm...its tough for me to do a comparison...as I have completely swapped engines...and lowered the Compression... But I AM getting a noticable difference in INCREASED gas mileage.

I can understand both sides of this topic.

Now nick...that is how you post

 

[YP5 Toronto]

and.... sorry I have noticed through the datalogs via the Haltech the coolant temperature is consistant with the "before and after"

 

[Brian MP5T]

That post MPNick made so much sense!!

 

[MPNick]

I am glad you like it. I will try to be more complete in my posts when I have the extra time. It is hard when I am running out the door to get to the shop.

Better gas maileage and lower emissions is one of the reason the OEM is looking more and more into coatings. The tighter you run the piston to wall clearance the better control you have on blow- by and the less noise you will have.

Thanks again


Later...........Nick

 

[ddogg777]

Any idea why the gas mileage would be better? Lowered compression? Sweet, sweet, head gasket? (lol, probably not)

Edit: Nevermind, I didn't quite read everything like I thought.

 

[MPNick]

and.... sorry I have noticed through the datalogs via the Haltech the coolant temperature is consistant with the "before and after"

You may see a little cooler water temps because you have less heat soaking into the cylinder walls from the pistons. It is the exhaust temps in the combustion chambers that will increase. This is why some people have the bottom of the valves and the exhaust ports coated. The OEMs have been able to downsize the cooling systems with changes made to pistons. Side coatings, heat coatings on piston tops and lower tension rings. Less drag on the engine means less heat the it will produce. Less heat soak into the cooling also means less total heat that the system needs to deal with. Keep in mind that all of these things are tested over many types of drive cycles. You may never see any changes with a EGT or a cooling temp gauge in everday driving. But you can bet that it is there. No OEM would spend one cent if they did not gain from it, and I am not talking about making more power.



Thanks again


Later..............Nick

 

[YP5 Toronto]

One theory is that with the increased heat in the combustion chamber...the CLEANER the fuel burn = increased efficency

Someone please correct me if I am wrong.

 

[ddogg777]

I'm thinking it would be more on the lines of more heat is converted to power rather than a cleaner burn...

Meaning that the burn can be the exact same but you're not losing heat (ie. power) by soaking the pistons and cylinders.

 

[Brian MP5T]

Sounds like regular forged pistons is the way to go...

 

[Equinox]

Not really. I had a backhalved 69 Camaro, 383, tunnel ram, 2 4bbl holleys, 3000rpm stall. Idled much smoother than the pro does with the AWR mounts. So did the 72 Chevelle with solid motor mounts. They sounded better, were much faster. Gas milage isn't much different though.

Used to own a 69 camaro, that's how I know =)

 

[MPNick]

you should have balanced your rotating mass to reduce vibrations. the fordged units are a little lighter than stock. that pretty much sums it up

On a in-line four cylinder engine lighter rods and or rods would cause a balance problem. In fact the aftermarket rods and pistons are better balanced then the stock units they replaced.

I do agree that you should have the balance checked when ever you build an engine.


Thanks again

Later..........Nick