Huge knock issue.

[engineermike]

Combustion. Coyote has a problem removing heat from 7/8 because of water flow. It normally happens when you do a lick/hit/pull/race then turn around and do another back to back

Do the stock gt or gt500 have the same issue?

Sponsored

 

[Jackson1320]

Do the stock gt or gt500 have the same issue?

Gt’s that have a couple bolt on mods and a aftermarket tuned or any kind of boost are known to have this problem. This is one reason why they ask you to install a lower thermostat. There has been Stock gt’s that have had this problem is they are drove hard for a long period of time.
gt500 I have not heard about them having this problem but I don’t really pay attention to gt500’s

 

[engineermike]

Ok well just a couple of things to think about...the gt and gt500 stock top ring gap is .008-.012 and the gt supercar is .008-.010. The ecoboost motors are all about the same. This didn’t make any sense to me when I first saw it because I came from the old school of thought where you need .025 for the top ring with boost to deal with the extra heat. Then I began modeling of combustion and when I added boost the peak temp did not change vs NA. It took me a minute to realize that, for instance, doubling the fuel also doubles the heat. But the mass of combustion gas is also double and the gas mass is what absorbs the heat of combustion. Therefore, the peak gas temp doesn’t significantly change. If the peak gas temp is the same, then the ring doesn’t run any hotter or expand any more than NA. The oem ring gaps suddenly made sense to me, as long as detonation is controlled. What probably broke the ring lands is detonation or perhaps just metal fatigue. Detonation often happens in the ring grooves so that’s where the damage shows up first, plus detonation does induce a higher peak temp at the metal surfaces. What I’m getting at is that widening the ring gap won’t always cure the problem but rather just a symptom. Also, the cal allows you to run less timing in specific cylinders. I’ll need to look tomorrow to see if Ford runs less timing in 7-8 in the gt and gt500.

 

[15GaurdGT]

How much does a good block and piston go for?

 

[sigintel]

GT500 and FordGT have better head cooling though?
Cooling limitations leads to embrittled aluminum pistons from excessive thermal cycles underload?

Only reason I didn't add pull the firewall freeze plugs on my 2015 Whipple was too lazy to pull motor to mod then refit, mod, refit, mod , refit... Bloody knuckles.
Used to wonder why people would cut a firewall....

Next build for sure though.

 

[Jackson1320]

Ok well just a couple of things to think about...the gt and gt500 stock top ring gap is .008-.012 and the gt supercar is .008-.010. The ecoboost motors are all about the same. This didn’t make any sense to me when I first saw it because I came from the old school of thought where you need .025 for the top ring with boost to deal with the extra heat. Then I began modeling of combustion and when I added boost the peak temp did not change vs NA. It took me a minute to realize that, for instance, doubling the fuel also doubles the heat. But the mass of combustion gas is also double and the gas mass is what absorbs the heat of combustion. Therefore, the peak gas temp doesn’t significantly change. If the peak gas temp is the same, then the ring doesn’t run any hotter or expand any more than NA. The oem ring gaps suddenly made sense to me, as long as detonation is controlled. What probably broke the ring lands is detonation or perhaps just metal fatigue. Detonation often happens in the ring grooves so that’s where the damage shows up first, plus detonation does induce a higher peak temp at the metal surfaces. What I’m getting at is that widening the ring gap won’t always cure the problem but rather just a symptom. Also, the cal allows you to run less timing in specific cylinders. I’ll need to look tomorrow to see if Ford runs less timing in 7-8 in the gt and gt500.

The problem is the #8 cylinder intake port does not have a water jacket so water doesn’t flow around 7/8 very well. So it gets hotter than all the rest. Without any temp sensor in the left head the ecu doesn’t know anything is wrong so it will not add fuel or remove timing. The cylinders get hot and sometimes detonate. Which makes more heat. If you are pushing the car you are making more combustion heat. if you can not remove that heat then heat builds up rings expand until they touch. Can detonation cause this damage? absolutely. It all comes from to much heat. When you install boost you retune the tune doesn’t always come out as good as factory tunes and aftermarket tunes tend to push the engine harder. They may run Them leaner or turn off fail safes. You are comparing a spot on NA tune to a spot on boost tune but we have no way of knowing if that’s the case. All I can say is that sometimes aftermarket tuned cars have this problem. I don’t know who tuned them or how well just that it happens. I have torn down many of these engines. So my guess ( that’s all it is a guess) based on what i have seen is that heat cause rings to expand and touch.

 

[engineermike]

I checked and the stock gt only pulls timing from cylinder 4, and it’s 2 deg. The gt500 doesn’t automatically pull timing from any individual cylinder. Both will retard individual cylinders due to knock and also retard globally due to coolant temp, iat, and lambda.

 

[markmurfie]

The theoretical Adiabatic flame temperature for gasoline is ~3880*F (flame temperatures produced by a flame that loses no heat ), but if you are looking at the temperature of rings or any other component you need to consider the heat transfer from the combustion into that component. It's not as simple as peak temp still reaches x* even with twice the amount of reactants, so the engines components will not get any hotter because the flames temperature didn't. Its true a lot of the heat goes into the combustion product gases and out the exhaust. Catalytic convertors melting is an example of that, and they usually do it when you are trying to push more fuel and air through the engine and putting too much heat into the exhaust. Its also true twice the fuel and air will produce twice the heat and a lot more work. This work increases heat transfer rates, heating up the engines components more, so their temperatures will be higher. Its why at idle and cruise a small radiator can be more than enough, but start pushing an engine hard and it quickly becomes insufficient at pulling enough heat out through the cylinder walls.

I would say OEM ring gaps are they way that they are from great metallurgy and finding the right hypereutectic properties to give very little heat expansion, but also not have too brittle of a material. Detonation (pressure wave hammering) and brittle materials don't mix well. Move to aftermarket rings that are less hypereutectic and less brittle and you will need the larger gap that is common in race purpose built engines.

 

[stanger1]

This is very interesting information. Love read this stuff.
I was thinking that Ford had loosened the Ring gaps on the gen 2 and 3 motors, just for Boosted applications, but maybe not. I have not actually looked at the gap specs between the Gens.

 

[Jackson1320]

I checked and the stock gt only pulls timing from cylinder 4, and it’s 2 deg. The gt500 doesn’t automatically pull timing from any individual cylinder. Both will retard individual cylinders due to knock and also retard globally due to coolant temp, iat, and lambda.

But there’s no coolant temp available for cylinder 7/8 and theses are the hottest cylinders. Google (coyote cylinder 8 problem) You will find hundreds of cases

 

[Jackson1320]

This is very interesting information. Love read this stuff.
I was thinking that Ford had loosened the Ring gaps on the gen 2 and 3 motors, just for Boosted applications, but maybe not. I have not actually looked at the gap specs between the Gens.

There all around the same about 0.0018. When I take them apart

 

[thelostotter]

There all around the same about 0.0018. When I take them apart

Interesting. On my 2017 with 19k miles #1-6 were all at 0.015", #7 was closer to 0.014" and I didn't check #8 because the bore was tore up.

NA engine, broken ring lands on #7-8, #6 was cracked but not completely failed yet.

 

[Bmaughan]

is this head cooling flaw still an issue if running e85?

I was thinking of also adding a water meth kit with perhaps a slight emphasis on the water to help with egt’s. I would think that would be more than enough to control cylinder temps without having to mess around with coolant flow. Thoughts??

 

[Torinate]

Anyone have experience with cylinder head temps with meth? I know it’s not fool proof due to where the sensor is, but if #4 drops temp, I would like to think that #8 would drop as well.

With the temp sensor at #4, would this not be indicative of #8 as well or does coolant flow from #4 elsewhere whereas it dead heads at #8?

Thanks!

 

[Jackson1320]

Interesting. On my 2017 with 19k miles #1-6 were all at 0.015", #7 was closer to 0.014" and I didn't check #8 because the bore was tore up.

NA engine, broken ring lands on #7-8, #6 was cracked but not completely failed yet.

I have had some at 0.016 and some at .020 but normally 0.017-0.018. Did you check each cylinder with the rings that came out of that cylinder or did you check them all with the same rings

Sponsored