Teardown and rebuild Thread: Converting GT350 race motor to CPC

[honeybadger]

Hi all,

Creating a new tear down and build thread for the motor. For those unfamiliar, while pulling the oil pan 2 weeks ago to see if the FPC vibrations had cracked the GT500 oil pickup tube (surprise, it did!), I found a main stud in the bottom of the pan. I decided to put the motor on a stand and do a full tear down to check all bearings, caps, rings, pistons, etc. Ultimately, I found a pair of cracks in the crank snout, so it's trashed. Plan is to replace with a CPC, drop in new cams, and re-pin the harness and send it. This thread will detail that process.

Please keep discussion educational/constructive around the swap, analysis of findings, etc. Would like to keep this thread informational for everyone vs. arguing over FPC vs. CPC, 5.2 vs. 5.0, GT350 vs. GT, etc. With that out of the way, let's jump in!

I have been taking video and that will share the step-by-step process, but wanted to start the conversation regarding some of the findings.

First up, the findings that triggered the tear down. Main stud in oil pan. Looks like the nut loosened up and it backed itself out.

From the #5 cap. Builder thought it might be because of a bad clutch/flywheel balance issue. Who knows.

Stud where the oil pickup tube broke off.

Broke right at the bend, just like the FP350S one did

Okay, further in. First thing I noticed is that my secondary tensioners are showing excessive wear on the top. Passenger side has almost worn all the way through

These have the FP GT4 pieces. They were replaced about 44 track hours ago. The set before ran 52 hours without issue. Only difference is I ran E85 exclusively this time vs about 80% in the previous refresh. I reached out to FP to see what they say.

Cams are beginning to show a bit more wear. Nothing particularly outrageous that I can see, but it's definitely got my attention now. Lobes still look good from my POV.

Heads off and I noticed some inconsistency in the way fuel appears to be burning. On one head, we have the intake valves two different shades - one gray and one black. However, on the other head, the same pattern appears to be limited to just one of the cylinders. Thoughts?

Piston tops like good from what I can see. Head gasket patterns looked good, I didn't see anything blown out or evidence of water/oil leaking

Flipping it over, here's some info on the bottom end. Bearings look great. We have that one gouge on #5 main, but it's not deep. Thinking maybe from a cold start?
#5 below

#3 cap and journal

Rod bearings and journals all looked like this. Still need to remove one to look at bottom

I don't have a good shot of the combustion chambers, but they all looked pretty good--much better than the previous refresh

Unfortunately, here's the big one

And here's where we sit now. Anything ya'll want to see before I remove the crank/pistons?

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[Decible]

Man hate to see that…the vibration must be really violent to walk a stud out, break the pickup, and crack the crank snout

 

[ChipG]

So you're saying you don't want to hear that you should LS swap it?

Interesting stuff, looking forward to following though I doubt I'll have anything helpful to add.

 

[honeybadger]

Man hate to see that…the vibration must be really violent to walk a stud out, break the pickup, and crack the crank snout

Very much so. I've had lots of informative convos regarding the FPC in the last week or so. Let's say this--the FPC won't ever be reliable outside of dead stock trim. My recommendation--don't tune, don't change NVH stuff (balancer, motor mounts, clutch, trans mount, or headers). Once you do, it's only a matter of time.

So you're saying you don't want to hear that you should LS swap it?

Interesting stuff, looking forward to following though I doubt I'll have anything helpful to add.

I'll allow the suggestion since it means you read the disclaimer ha! But no, no LS swaps. If anything because I don't want to learn an entirely platform right now. ha

 

[Cordero1]

I have nothing constructive to add but sure am subbed to try to sponge some knowledge up.

 

[331GT]

your comment about running e85 exclusively vs about 80% of the time previously- is there an implication with that or just an observation? just curious as to why you'd point that out and what it might mean.

Thanks for posting the pics/details. i am surprised as well that a main stud would walk itself out like that.

 

[honeybadger]

your comment about running e85 exclusively vs about 80% of the time previously- is there an implication with that or just an observation? just curious as to why you'd point that out and what it might mean.

Thanks for posting the pics/details. i am surprised as well that a main stud would walk itself out like that.

Some not-to-be-named company has said that the OEM plastics/guides aren't built to handle E85. But I have yet to see evidence that it's more than a marketing claim for a product they offer. If it were true, I'd have expected to have an issue before now, but I want to be transparent that I do run E85 exclusively now vs. just most of the time before. We'll see what the Ford Engineers say.

 

[Bulldogs22]

Some not-to-be-named company has said that the OEM plastics/guides aren't built to handle E85. But I have yet to see evidence that it's more than a marketing claim for a product they offer. If it were true, I'd have expected to have an issue before now, but I want to be transparent that I do run E85 exclusively now vs. just most of the time before. We'll see what the Ford Engineers say.

Interesting thread. After warranty period is over wanted to tune E85 with factory headers but high flow cats, jlt intake, and soler engineering throttle body, but will not be doing this if any of these will cause the FPC to for sure fail eventually

 

[331GT]

Some not-to-be-named company has said that the OEM plastics/guides aren't built to handle E85. But I have yet to see evidence that it's more than a marketing claim for a product they offer. If it were true, I'd have expected to have an issue before now, but I want to be transparent that I do run E85 exclusively now vs. just most of the time before. We'll see what the Ford Engineers say.

thanks! was just curious of any tech implications of potential issues.

 

[Demonic]

Kevin do you know about how much power you were making on the previous build?

 

[honeybadger]

Kevin do you know about how much power you were making on the previous build?

 

[Demonic]

Oh man, 500 at the wheels. Better to have loved and lost? Do you have a hp/tq target for the CPC build?

 

[Decible]

Very much so. I've had lots of informative convos regarding the FPC in the last week or so. Let's say this--the FPC won't ever be reliable outside of dead stock trim. My recommendation--don't tune, don't change NVH stuff (balancer, motor mounts, clutch, trans mount, or headers). Once you do, it's only a matter of time.





I'll allow the suggestion since it means you read the disclaimer ha! But no, no LS swaps. If anything because I don't want to learn an entirely platform right now. ha

Awww man the ls swap all you need to learn is in your right foot. 427 ci lots of low end torque and still 8k rpm when built

 

[TonyNJ]

So for the uninitiated, like myself, you amped up the power on the flat plane crank, raced it many times with e85, eventually got heavy vibration and now you're changing the crank to a cross plane? Sorry for the obvious question but I want to follow correctly.

52 track hours on the engine, then 44 track hours on a rebuild? How long was the factory engine around for?

Has this ever been done, and documented on the 5.2 Voodoo? And is it still a Voodoo or a Frankenstein after the FPC is changed out? Lastly, can us with the factory built engine expect these vibration bolt loosening issues from agreesive street driving or is it from the mods?

Very interesting stuff you're doing. I'll be watching. Good luck!!

 

[honeybadger]

Oh man, 500 at the wheels. Better to have loved and lost? Do you have a hp/tq target for the CPC build?

Short term, not sure. But i'd like north of 540. I *should* be adding power with upgraded cams, but not 100%. I should also add some midrange and lose some RPM. Hoping to be able to hit 8k, but will try to shift between 7.5-7.8 depending on track and power band.

So for the uninitiated, like myself, you amped up the power on the flat plane crank, raced it many times with e85, eventually got heavy vibration and now you're changing the crank to a cross plane? Sorry for the obvious question but I want to follow correctly.

52 track hours on the engine, then 44 track hours on a rebuild? How long was the factory engine around for?

Has this ever been done, and documented on the 5.2 Voodoo? And is it still a Voodoo or a Frankenstein after the FPC is changed out? Lastly, can us with the factory built engine expect these vibration bolt loosening issues from agreesive street driving or is it from the mods?

Very interesting stuff you're doing. I'll be watching. Good luck!!

I never really got heavy vibration. In fact, I'd argue most of the work we did made it run much smoother. But due to the design, it'll still fatigue parts--especially the crank snout. This is the original crank 23k miles - all but ~7k of which are track miles.

I am far from the first to drop a CPC into a Voodoo for road course use, but I am not sure I've seen much detail on the engine specific bits.

Just don't mod the motor/supporting parts and I think you'll be okay. Street driving is also mostly okay. It's the extended 5-8K rpm use that causes issues.

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