Another pistons / short block / what should I do thread

[Camel City]

Hey guys, long time lurker, first time poster. I bought a 2016 GT with the Hellion top mount kit a couple of years ago, knowing that it needed a short block (low compression in cylinder 8, pretty sure it's a cracked ring land). The car is still drivable and runs pretty strong, but I'm finally getting around to pulling the engine and fixing it right. 48k miles on the car, roughly 25k with the turbo kit. It's a 6 speed, Tremec Magnum XL, subframe connectors, axles, driveshaft, it's built well.

I think I've read pretty much every short block, pistons, rods, etc thread on here, and I'm still not sure what direction I want to take. The previous owner got about 25k miles out of the gen 2 short block on 93 octane, so the cheapest and simplest route is to just get a Gen 3 short block and maybe gap the rings. I do plan to go with E85, it's fairly cheap and available in my area, so I'm not too worried about the higher compression. It has a Fore Innovation 2 pump system, not sure about pump sizes, and 95lb injectors. I don't have a specific power goal in mind, 800+ RWHP would be great, but I don't know how much past that the injectors would handle on E85.

Part of me really wants to buy the parts and assemble the short block myself. I think I would get a lot of satisfaction out of knowing that I did the work myself, and took the time to do it properly. I've never done it before, but I'm fairly technical and can read a manual. With the fairly cheap availability of machined blocks and components, my expectation is that I can take my time and bolt everything together myself, minus the crankshaft balancing. I have a family history of machinists and tool & die makers, so I understand clearances and precise measurements.

Now for the questions. The first one is on piston material. This is a street car, it might see some 1/8 mile passes every now and then, but my ultimate goal is reliable, reasonable power. I'd love an engine that can do another 50k+ miles without having to worry about it, and that seems to point me to 4032 forged pistons. I'd prefer to stay away from 2618 and the increased wear, noise, etc. The problem is that I've found almost no one that actually offers off the shelf 4032 pistons for a Gen 3 coyote. The only option I've found is DSS, and I haven't seen much feedback on those or folks that are running them. I emailed both Mahle and Manley since they previously made 4032 pistons for Coyotes, and they confirmed that they're not available for the Gen 3. Manley offered no explanation, and Mahle said there little demand, but feedback/requests could cause them to be available in the future.

I guess what I'm wondering is does anyone really know WHY there are so few options for 4032 pistons for the Gen 3 Coyotes? Is it just not that much of an upgrade over stock? Is there any issues with them and the PTWA cylinder walls? Are the 2618 options with advanced coatings "good enough" for a street car?

While I'm rambling, one thing I've also been looking at is going with the Predator block. For the cost, it seems like a good upgrade for not a ton of money, and I've found that Mahle does make the drop in "Voodoo" pistons in M142P that could be used. From my understanding the pin diameter is a bit smaller on these, so I'd need to run Voodoo specific rods, but rod length is the same. A boss crank would then put them just slightly lower in the bore (~.006" or there abouts), slightly lowering the compression. I'm pretty sure Olaosunt built something similar, or maybe the same thing. I haven't searched as hard to see if there are other piston options in the 3.700 bore size in 4032, but I haven't run across much yet.

I guess I'm looking for some guidance or wisdom. I'd love to get some parts on order, I've been thinking about this off and on for 2 years now and haven't really got anywhere with it.

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[Timbuck]

Hi

i had a similar thought process to you. I’ve never build a coyote , but the best option for me was to re-build me gen2. (as I’m in Australia). Import duty and shipping makes it crazy $$$

I just got the bottom end sleeved and built and I did everything else.

after a million hrs of research. Contacting piston companies etc. I ended up with M142p pistons , Callie’s rods , darton sleeves. stock bore and stroke sizes so I have the ability to re-build again in the future if needed. ( hope not for a while haha).
also this rod and piston combo allowed me to still keep factory oil squirters. Yes there is debate to have them or not. But the way I look at it is nascar , Ferrari , lambo , heaps of races cars and the list goes on all use squirters. So I liked the idea of keeping them.

As it is street car I liked the idea of a piston that heated up quickly , didn’t expand much , and has tight OEM type tolerances and gives similar strength and resistance to knock as a 2618 or 4032.
kind Of gives you the best of both worlds.

cheers

tim

 

[Camel City]

Thanks for your perspective Tim, the M142P pistons do seem like a great option. I just wish they were available in the Gen 3 bore size off the shelf, I'd rather avoid going custom.

I can't see reusing my Gen 2 block making much sense in my case, the new blocks here are just too cheap to fool with machine work, and I don't plan to make enough power where the sleeves are necessary.

The piston oil squirters are one of those things that opinions seem to be pretty mixed on. I can see pros and cons, but overall I think Ford put them there (sometimes) for a reason.

How many miles do you have on your build? Any indication how it's holding up? I'd love to put together something could handle 50k+ miles before needing refreshing, I figure your setup should do that and then some.

 

[Timbuck]

Have you pulled yours apart yet ? is there any damage to that cylinder ? Check it with a bore scope.
you might find there is nothing wrong with it and you can just give it a clean up , replace pistons and rods and away you go again.
or
If you do get a new gen3 block , and you are keen on m142p pistons just order a custom set. from memory it’s not more money you just have to Wait 6 weeks for some thing.

mine is running awesome very happy… runs like a clock and very smooth running. 10K miles.
now just got to decide what boost I’ll go. 99% on twins.

it was another one of the reasons I went m142P pistons is they last like oem , with a life of 150,000 +miles so to speak.

 

[mepawn]

So i cant attest to the piston type but i did also recently have an engine rebuild. I actually used RPG to build my short block. I ended up going with a 5.2L block that was sleeved and i provided a coyote callies crank and molnar power adder plus rods. RPG then provided their spec'd pistons and assembled the short block. I also did delete the oil squirters to help increase oil pressure in the rest of the engine. My car is street driven with plenty of track use and good for 2k whp but i only run it at 1kwhp. This build should last me sometime and certainly not concerned about its longevity due to the overbuild.

 

[HKusp]

If you want longevity and you are going to run it primarily on ethanol, use stock pistons, ARP hardware, stock rods, stock crank and gap the rings for boost just to be sure. Make sure your tuning is right and knock protection is turned on. Change your oil on time and you'll have a block that lives a long and happy life. The stock bottom end on these cars is pretty stout. No need to get super exotic. If I had it to do over again, I would have went stock pistons, and forgone the 2618's for sure.

Edit: All of the above is assuming you are correct about the cause of the problem being a piston ring or ring land. I would also send the heads off and have them checked and add new PAC springs or similar with more pressure because turbo's are known for valve float and that COULD be a problem as well. Why you're in there it wouldn't be a bad idea.

 

[robvas]

Are the stock gen3 shortblocks reliable in something like a 1/2 mile run, or in that case would an aftermarket ring/piston be better?

After how many miles would it be a good idea to refresh the stock heads?

 

[mepawn]

Are the stock gen3 shortblocks reliable in something like a 1/2 mile run, or in that case would an aftermarket ring/piston be better?

After how many miles would it be a good idea to refresh the stock heads?

Realistically the gen 3 shortblocks are super stout and good for about 800hp without much issue provided you do oil pump gears at least along with proper maintenance.

I usually do the 1/4 mile but i would imagine they would be fine in the 1/2 mile provided youre not redlining the engine for most of it, adjust the rear gearing to suit.

 

[Camel City]

Have you pulled yours apart yet ? is there any damage to that cylinder ? Check it with a bore scope.
you might find there is nothing wrong with it and you can just give it a clean up , replace pistons and rods and away you go again.
or
If you do get a new gen3 block , and you are keen on m142p pistons just order a custom set. from memory it’s not more money you just have to Wait 6 weeks for some thing.

mine is running awesome very happy… runs like a clock and very smooth running. 10K miles.
now just got to decide what boost I’ll go. 99% on twins.

it was another one of the reasons I went m142P pistons is they last like oem , with a life of 150,000 +miles so to speak.

Haven't taken it apart yet, I did do a compression and leak down test though. Results are below, cylinder 8 did go from 130 PSI to ~170 PSI after adding a small amount of oil through the spark plug hole. I was hoping I might lucky and it be a head gasket, but nope.

Cylinder
1 - 205 PSI 9% leakage
2 - 200 PSI 7% leakage
3 - 205 PSI 8% leakage
4 - 185 PSI 19% leakage, air at oil fill cap
5 - 185 PSI 20% leakage, air at oil fill cap
6 - 210 PSI 9% leakage
7 - 190 PSI 21% leakage, air at oil fill cap
8 - 130 PSI 75% leakage, air at oil fill cap

I've got a cheap bore scope that I used during the test to make sure the pistons were TDC and valves were closed, I couldn't see well enough to determine conditions of the piston or cylinder though.

If you want longevity and you are going to run it primarily on ethanol, use stock pistons, ARP hardware, stock rods, stock crank and gap the rings for boost just to be sure. Make sure your tuning is right and knock protection is turned on. Change your oil on time and you'll have a block that lives a long and happy life. The stock bottom end on these cars is pretty stout. No need to get super exotic. If I had it to do over again, I would have went stock pistons, and forgone the 2618's for sure.

Edit: All of the above is assuming you are correct about the cause of the problem being a piston ring or ring land. I would also send the heads off and have them checked and add new PAC springs or similar with more pressure because turbo's are known for valve float and that COULD be a problem as well. Why you're in there it wouldn't be a bad idea.

I do plan to do the exhaust valve springs for sure, I've read the Hellion top mount kit isn't great with back pressure, so the valves can float early. I was hoping to get by with cleaning up the heads myself if they look alright, perhaps that's foolish though.

I'm afraid if I do go the stock rods and pistons and ethanol, the turbos and rest of the car are going to be capable of more, and I'll be tempted to push it.

 

[EFI]

I ended up with M142p pistons

What piston size did you go with? Do you have a part number for those?

 

[Timbuck]

What piston size did you go with? Do you have a part number for those?

As I was sleeving the engine. I went 10 over ,so we had some wiggle room for the machinist to get everything perfect and true. also I got him to make a custom torque plate to bolt up with ARP studs just to make sure the block was held true while honing.

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