Switch from Flat Plane Crank to Cross Plane Crank Build

[Texas_Muscle5.2]

Does anyone have good advice on Cross Plane Crank build for the GT350? I know the cams need to be changed and repinned for the CPC firing order. Unfortunately today loss compression in Cylinder 6-8, on a built sleeved motor. If I’m going to crack this motor open again she is going to be a CPC.

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[olaosunt]

sorry to hear that man . Do you know what may have happened ?

Did you say this was your second engine ?

Who built this one ?

I will always have a spare engine as long as I own the car . At one point I kept 2 but sold one.
The engine in the car is now a mild build with upgraded rods / head studs and PAC springs but I have an RPG sleeved motor as a spare .

 

[Inthehighdesert]

That sucks. Be interested in knowing what the failure actually was. I don’t recall. Were you on E85, how turned up is your application. Depending on what the conversion runs, a coyote swap and oem rebuild may be a consideration.

 

[Texas_Muscle5.2]

sorry to hear that man . Do you know what may have happened ?

Did you say this was your second engine ?

Who built this one ?

I will always have a spare engine as long as I own the car . At one point I kept 2 but sold one.
The engine in the car is now a mild build with upgraded rods / head studs and PAC springs but I have an RPG sleeved motor as a spare .

Will Rollins is one of my buddies but he didn’t build my current motor. Lund stated on the log that everything was perfectly fine, I had no issues once I did a WOT pull that the car was acting strange. I came to a light and noticed she was making noise as if I broke the header again. Once I stopped at the builder shop I showed him the log and he confirmed everything looked great. I read for any codes and noticed intermittent lost of signal at the crankshaft position sensor and misfiring in cylinder 6. We ran a compression test and noticed the loss in cylinder 6. We ran a bore scope down in the cylinder noticing slight burning in the edge of the piston. Valves look great so I’m happy with that.

Below is my current build list:
Gen 3 2.9 Whipple Supercharger

132mm Whipple TB

123mm Whipple Intake

Darton Racing Sleeves

2020 GT500 Predator Block

Flat Plane Crank

Manley Extreme I Beam Rods

Manley Extreme 12:1 Pistons

King Racing Bearings

ARP Head Studs

ARP Main Studs

ARP Side Studs

Ferrea Valves-Stock Size

PAC Valve Springs-Stock Size

Mishimoto Radiator

170 Degree Riesche Thermostat

ATI Damper-Stock Diameter

Boundary Oil Pump Gears

Boundary Crank Gear Sprocket

MMR Timing Chain Guides

MMR Secondary and Primary Tensioners

Stainless Works Longtube Headers

OEM GT500 Catback

MBRP X Pipe

Fore Double Pump Fuel System (TI Automotive F90000267 Fuel Pumps)

Injector Dynamics ID1050X

UPR Breather Catch Can

Active Exhaust Valve Deletes

Ford Performance 200amp Alternator

Brisk Spark Plugs RR12S (Gapped .028)

 

[Texas_Muscle5.2]

That sucks. Be interested in knowing what the failure actually was. I don’t recall. Were you on E85, how turned up is your application. Depending on what the conversion runs, a coyote swap and oem rebuild may be a consideration.

I was on E85, and running about 15psi. The motor is sleeved so I should be about to clean up the sleeves stuff some new pistons, Gen 2 Cams, lash adjusters, Cross Plane Crank and run the 15-17 GT Harness to change the firing order. I should be able to contact Lund to change firing order to Cross Plane firing order vice Flat Plane. It’s going to cost me about 6-8k to redo this one. I can turn the redline up to 8,200rpm on the new build.

 

[olaosunt]

Will Rollins is one of my buddies but he didn’t build my current motor. Lund stated on the log that everything was perfectly fine, I had no issues once I did a WOT pull that the car was acting strange. I came to a light and noticed she was making noise as if I broke the header again. Once I stopped at the builder shop I showed him the log and he confirmed everything looked great. I read for any codes and noticed intermittent lost of signal at the crankshaft position sensor and misfiring in cylinder 6. We ran a compression test and noticed the loss in cylinder 6. We ran a bore scope down in the cylinder noticing slight burning in the edge of the piston. Valves look great so I’m happy with that.

Below is my current build list:
Gen 3 2.9 Whipple Supercharger

132mm Whipple TB

123mm Whipple Intake

Darton Racing Sleeves

2020 GT500 Predator Block

Flat Plane Crank

Manley Extreme I Beam Rods

Manley Extreme 12:1 Pistons

King Racing Bearings

ARP Head Studs

ARP Main Studs

ARP Side Studs

Ferrea Valves-Stock Size

PAC Valve Springs-Stock Size

Mishimoto Radiator

170 Degree Riesche Thermostat

ATI Damper-Stock Diameter

Boundary Oil Pump Gears

Boundary Crank Gear Sprocket

MMR Timing Chain Guides

MMR Secondary and Primary Tensioners

Stainless Works Longtube Headers

OEM GT500 Catback

MBRP X Pipe

Fore Double Pump Fuel System (TI Automotive F90000267 Fuel Pumps)

Injector Dynamics ID1050X

UPR Breather Catch Can

Active Exhaust Valve Deletes

Ford Performance 200amp Alternator

Brisk Spark Plugs RR12S (Gapped .028)

Wow .. cant be any more built than that .

what pulley size ?
I also run the same Whipple blower on my mild built motor(Gen 1 block so not as stout as the predator in yours )but only a 3.375 pulley (ran down to a 3 inch grip tech but I think it was slipping ) and ID 1300’s/ triple pumps .

You think the failure is related to the Flat plane crank ?
Fuel related by chance ?

 

[Texas_Muscle5.2]

Wow .. cant be any more built than that .

what pulley size ?
I also run the same Whipple blower on my mild built motor(Gen 1 block so not as stout as the predator in yours )but only a 3.375 pulley (ran down to a 3 inch grip tech but I think it was slipping ) and ID 1300’s/ triple pumps .

You think the failure is related to the Flat plane crank ?
Fuel related by chance ?

Honestly I saw a bit of detonation on the Cylinder 6 plug. Fuel trims were all within 5% so I’m unsure to be totally honest.

 

[olaosunt]

I was on E85, and running about 15psi. The motor is sleeved so I should be about to clean up the sleeves stuff some new pistons, Gen 2 Cams, lash adjusters, Cross Plane Crank and run the 15-17 GT Harness to change the firing order. I should be able to contact Lund to change firing order to Cross Plane firing order vice Flat Plane. It’s going to cost me about 6-8k to redo this one. I can turn the redline up to 8,200rpm on the new build.

May be a leak down test as the failure could be the top end ?
if you do rebuild with cross plane crank , you can keep the same lash adjuster with the 5.2 cross plane cams .

The 5.2 crank is about $1200 , 5.2 cams about $1600.

 

[Texas_Muscle5.2]

May be a leak down test as the failure could be the top end ?
if you do rebuild with cross plane crank , you can keep the same lash adjuster with the 5.2 cross plane cams .

The 5.2 crank is about $1200 , 5.2 cams about $1600.

We’re going a leak down test to see what the issue is, and I’m not to thrilled being that is has build heads. I guess you have to pay to play.

 

[olaosunt]

We’re going a leak down test to see what the issue is, and I’m not to thrilled being that is has build heads. I guess you have to pay to play.

You already paid

 

[Texas_Muscle5.2]

You already paid

That’s a fact dude

 

[stanglife]

With those mods - would be hard to point a finger specifically at the FPC. Sounds like you are -but I'd definitely dig until I found the actual failure before I gave up the FPC sounds - that thing on boost must sound pretty crazy.

 

[rolfe.oliver]

So sorry to hear about the issues. Why the jump to CPC versus keeping the FPC? I may be wrong, but out of all the high horsepower voodoos out there, the crank seems to be a strong point. Though just a sample size, I believe Fathouse uses FFRE for their built engines and they retain the flat plane crank up to ~2,000hp in their fox body.

Based on your description, fueling and tuning seemed spot on, so it seems like a freak motor failure. Also, when you say you can turn the redline up to 8,200 on the new build, why is your current rev limiter lower?

 

[furdfan2018]

How much timing?

Something not adding up here. You should be able to handle 15 psi easily with that motor build. e85 only exaggerates the point (safe).

 

[olaosunt]

OP, with how much you have in all other parts build not sure if you skimped out on fueling

My GT 350 was making 920 hp at the wheels @16 psi /ID1300’s / triple pumps
if you are making close to that @15psu , could the 1050’s /dual pump be maxed out ?

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