Teardown and rebuild Thread: Converting GT350 race motor to CPC

[JAJ]

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?

So, I knew there was a thread on this exact topic somewhere and I found it on TMO. It's here:

S550 - GT350R Race Car Build Build Thread | TrackMustangsOnline.com

User "spartan" did a FPC to CPC conversion along the way - look at the posts starting in Jan-Feb 2018 and you'll see a lot of good information on the topic. As I recall, that's where the firing order sheet came from.

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[honeybadger]

So, I knew there was a thread on this exact topic somewhere and I found it on TMO. It's here:

S550 - GT350R Race Car Build Build Thread | TrackMustangsOnline.com

User "spartan" did a FPC to CPC conversion along the way - look at the posts starting in Jan-Feb 2018 and you'll see a lot of good information on the topic. As I recall, that's where the firing order sheet came from.

Yep - I've followed both Nick and Fred's journeys closely. I plan to add to their efforts with details on the motors themselves. I'll be doing the re-assembly in the ol' garage this time. Tim is just sending me a balanced crank to drop in.

 

[UnhandledException]

Didnt you recently change the flywheel to a lighter one? I apologize if I am confusing it with another member. I follow your channel very closely and watched every one of your winter refresh videos at least 5 times now, end to end, without skipping But lighter flywheel is probably not cooperating with vodooo?

 

[honeybadger]

Didnt you recently change the flywheel to a lighter one? I apologize if I am confusing it with another member. I follow your channel very closely and watched every one of your winter refresh videos at least 5 times now, end to end, without skipping But lighter flywheel is probably not cooperating with vodooo?

I did, I installed it, but never ran it. Once I found the header rubbing on the on the frame rail, I stopped the install to replace the motor mounts. As they say, one thing led to another and now I have an engine in a million pieces all over the garage

 

[UnhandledException]

I did, I installed it, but never ran it. Once I found the header rubbing on the on the frame rail, I stopped the install to replace the motor mounts. As they say, one thing led to another and now I have an engine in a million pieces all over the garage

Do you think the changes in your motor has caused these issues or its just inherent flaws of the FPC design compounded with the wrong material being used? The only other high revving N/A I know is Porsche’s GT3 engine which takes quite a bit abuse but I have never seen this type of damage. You also had other issues in your videos if I recall correctly where the oil pick up tube had broke apart.

By the way, my whole family watches your videos including your laps with our surround sound speakers. Your videos are my favorite and I have a GT3RS and a ZR1 in my garage. That says a lot about your content!

 

[Angrey]

So the obvious question is what engine management you'll use. I wonder if it's possible to revert the CPC tune back to the modular firing order. Not that it matters, but one of the most compelling features of the voodoo is the sound. The coyote reverted back to the "flathead" firing order. Somewhere in my memory, I remember reading that Ford squeezed out a whopping 4 hp (crank) by using the flathead firing order. But to me, it sounds so much worse than the modular firing order. The 4V modulars sounded magical. The coyote sounds trashy and unrefined. Would be interesting if you're gonna just run a coyote PCM or go with something custom.

 

[JAJ]

...I'll be doing the re-assembly in the ol' garage this time...

Ah, yes. Get our your three pound hammer, a cold chisel and a cutting torch and you won't have any trouble getting the stuck bits apart

 

[JAJ]

Yep - I've followed both Nick and Fred's journeys closely. I plan to add to their efforts with details on the motors themselves. I'll be doing the re-assembly in the ol' garage this time. Tim is just sending me a balanced crank to drop in.

Now for some real input - I was bored a while back and did a bunch of reading about crank balancers. There seems to be a lot of science baked into the factory pieces, and it might be worth looking into a few alternatives to ATI. I'm not saying that there's anything wrong with ATI, but you have a cracked crank and mangled timing chain tensioners, which happen to be connected to each other by short lengths of timing chain.

If you're looking to spend a lot of time at high RPM with this engine, it might be worth spending some extra time evaluating the various options - OEM units, hydraulic units and the regular ones like ATI. Everyone says theirs is the best, but some might be bester than others.

 

[honeybadger]

Do you think the changes in your motor has caused these issues or its just inherent flaws of the FPC design compounded with the wrong material being used? The only other high revving N/A I know is Porsche’s GT3 engine which takes quite a bit abuse but I have never seen this type of damage. You also had other issues in your videos if I recall correctly where the oil pick up tube had broke apart.

By the way, my whole family watches your videos including your laps with our surround sound speakers. Your videos are my favorite and I have a GT3RS and a ZR1 in my garage. That says a lot about your content!

I don't know if it's all or mostly, but the inherent design is the biggest contributor. The clearest explanation I heard last week during my convos was "they just can't dampen it enough to compensate for the vibrations." If understood correctly, the bore/stroke ratio, length of the snout, weight of the rotating assembly, firing order, etc. are all not optimal for managing vibrations. On top of the Coyote architecture never being developed for race use, you just have a lot of challenges to overcome. And when I pushed hard, I was told there's nothing you can do. They tried with the GT350RC and they just couldn't get it right. The new part I learned was around the crank snout/balancer issues. I think most of us assumed it was vibrating bolts loose, bad powerband, poor reliability, but the impression I got was more tied to the crank snout reliability.

Appreciate the kind words

So the obvious question is what engine management you'll use. I wonder if it's possible to revert the CPC tune back to the modular firing order. Not that it matters, but one of the most compelling features of the voodoo is the sound. The coyote reverted back to the "flathead" firing order. Somewhere in my memory, I remember reading that Ford squeezed out a whopping 4 hp (crank) by using the flathead firing order. But to me, it sounds so much worse than the modular firing order. The 4V modulars sounded magical. The coyote sounds trashy and unrefined. Would be interesting if you're gonna just run a coyote PCM or go with something custom.

You can use the OEM computer. Just re-pin and the tuner manages the rest.

Ah, yes. Get our your three pound hammer, a cold chisel and a cutting torch and you won't have any trouble getting the stuck bits apart

Now we're talking. I love me a good blow torch and hammer

 

[honeybadger]

Now for some real input - I was bored a while back and did a bunch of reading about crank balancers. There seems to be a lot of science baked into the factory pieces, and it might be worth looking into a few alternatives to ATI. I'm not saying that there's anything wrong with ATI, but you have a cracked crank and mangled timing chain tensioners, which happen to be connected to each other by short lengths of timing chain.

If you're looking to spend a lot of time at high RPM with this engine, it might be worth spending some extra time evaluating the various options - OEM units, hydraulic units and the regular ones like ATI. Everyone says theirs is the best, but some might be bester than others.

Ya. I noticed the GT4 engine uses some modified version of OEM (at least it looks like it). I have some inquiries out. I'm also trying to see if Dean can hook me up with that special dry sump oil tank

One thing I can't deny...the crank failed with the ATI balancer on it after lasting with the OEM. Could be a coincident...maybe not. Needless to say, I have research to do. Hopefully Dean or Capaldi can shed some light

 

[TonyNJ]

@UnhandledException

By the way, my whole family watches your videos including your laps with our surround sound speakers. Your videos are my favorite and I have a GT3RS and a ZR1 in my garage. That says a lot about your content!
[/QUOTE]
Lolol. I just went to his YouTube and watched the Circuit of the Americas from 2 months ago. Holy hell. Screamer. Awesome.

 

[barstowpo]

At your last refresh, was the crank fully inspected? Is this something that could have been brewing for some time? I really appreciate all the research and experimentation you have been doing and also your transparency with the forums.

 

[shogun32]

I wonder if it's possible to revert the CPC tune back to the modular firing order.

https://fordfiringorder.com/ford-modular-firing-order/ was illuminating.

the fatigue on the oil pickup tab suggests there's fairly large amplitude to the free-end. Would be interesting to put a bunch of weight on the end, or better yet put a rubber ring on the bell and weld something to the pan to significantly limit freedom of motion. Or something vastly cheaper like chop off the metal tube and use a bit of rubber hose like an elephant nose?

I can't imagine how E85 would get into the crank-case so much so that it would be flinging around on the cam chains and dissolving chain guides. That would be a massive failure of cylinder integrity, no? It seems rather more likely the tensioner mis-behaved and ratcheted a notch or two past where it should have and thus had enormous strain on the chain and thus the guide got chewed down to nothing.

The scratch in the bearing looks like a big enough piece of carbon happened to find a moment to hang out before ending up in the filter.

The valve color is indeed curious. Is there a pathology in the intake charge turbulence that the flame-front is heavily biased to one half of the cylinder and thus the other half stays 'cold' and accumulates soot instead of burning it off? Does the other side of the engine tumble more equally? was the heavily worn chain guide on the side with the black valves?

 

[Mrhavasu]

You also stated problems most likely to be in the 5 to 8k rpm ranges. I wonder,
does anyone know how the Ford school cars held up since they probably
mostly lived in that range?
Thanks

 

[barstowpo]

I have a school car. It had the engine and transmission replaced due to a flywheel failure failure that cracked the block and transmission. I don't remember at what mileage but the car has 14,185 miles on it now.

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