GT350 Engine Refresh Time!

[bauern]

Question for the experts
If you are swapping pistons either in a FP or CP build , do they have to specially “clearanced ” for the high lift cams (Voodoo or ford racing ?)

A piston designed for the Voodoo will not need clearancing as the cam lobes are identical between FP and CP camshafts.

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[Dominator961]

A piston designed for the Voodoo will not need clearancing as the cam lobes are identical between FP and CP camshafts.

I think he meant because the voodoo has 14mm lift. That’s more than a coyote.
Valve to piston clearance always needs to be checked. As does compression height

 

[AceOne]

I think he meant because the voodoo has 14mm lift. That’s more than a coyote.
Valve to piston clearance always needs to be checked. As does compression height

Correct but the cams for the Voodoo with 14mm lift and 270 duration are also the same specs used for the 5.2 CPC conversion cams so the PTV is same if you are using stock pistons. OEM dome is 7.8 cc.

 

[Dominator961]

Correct but the cams for the Voodoo with 14mm lift and 270 duration are also the same specs used for the 5.2 CPC conversion cams so the PTV is same if you are using stock pistons. OEM dome is 7.8 cc.

Correct I was aware of that. Only difference are the cams firing order.

 

[olaosunt]

Thanks guys .
I have just had my CPC 5.2 long block assembled.
I started with a brand new 15 GT block, BES sleeved to 3.7 bore and built with Ross 11.1 pistons and Manley rods .
I am not sure if the pistons were “GT 350 specific”
so hoping I don’t have any PV contact .

The GT 350 heads were cleaned but not ported and assembled with the Ford performance GT 350 spec cams . I used the “upgraded” phasers and lifters and OEM rocker arms .
Of course oil pump with billet gears /crank sprocket and GT oil pan . It’s complete form pan to covers .
It’s a replacement motor for the one currently in one of my 15 GT’s with 3.2 KB
The motor in it now has an MMR built/sleveve 5.2 and started off with GT 350 heads(stock GT cams ) but swapped to GT heads when I was replacing a blown head gasket and found the heads hadsome scoring .
Car now makes 950-1000 rwhp with 18 psi but is lifting the heads on the dyno .
I am hoping to get a few passes(hopefully a 9 second with the Magnum XL ) out of it before I swap in the new motor .Car will probably be for sale then if I can resist racing(drag) it again .

I am sure I will have it on the dyno to get it dialed in since the cams will need a different tune .

With hind sight I should probably have started off with Gen 5.2 block (sleeved or unsleeved) since it uses 12 mm bolts /studs which would have helped the head lift issues

 

[AceOne]

Thanks guys .
I have just had my CPC 5.2 long block assembled.
I started with a brand new 15 GT block, BES sleeved to 3.7 bore and built with Ross 11.1 pistons and Manley rods .
I am not sure if the pistons were “GT 350 specific”
so hoping I don’t have any PV contact .

The GT 350 heads were cleaned but not ported and assembled with the Ford performance GT 350 spec cams . I used the “upgraded” phasers and lifters and OEM rocker arms .
Of course oil pump with billet gears /crank sprocket and GT oil pan . It’s complete form pan to covers .
It’s a replacement motor for the one currently in one of my 15 GT’s with 3.2 KB
The motor in it now has an MMR built/sleveve 5.2 and started off with GT 350 heads(stock GT cams ) but swapped to GT heads when I was replacing a blown head gasket and found the heads hadsome scoring .
Car now makes 950-1000 rwhp with 18 psi but is lifting the heads on the dyno .
I am hoping to get a few passes(hopefully a 9 second with the Magnum XL ) out of it before I swap in the new motor .Car will probably be for sale then if I can resist racing(drag) it again .

I am sure I will have it on the dyno to get it dialed in since the cams will need a different tune .

With hind sight I should probably have started off with Gen 5.2 block (sleeved or unsleeved) since it uses 12 mm bolts /studs which would have helped the head lift issues

I would check Piston to valve clearance. The valve pocket don't look near as deep as what is in the Voodoo. 11:1 is less dome so that may be the reason. OEM 12:1 Mahle pistons are 9.8 cc dome and -2 cc for the pockets.

Looks like a nice build though. Coyote crank or the Voodoo? There is a slight bit more stroke in the Voodoo so a Coyote crank would give you .0055 more PTV clearance than the Voodoo.

How many miles/passes on the MMR engine? Will you post the tear down of it?

 

[olaosunt]

Thanks for your expertise .
Crank is coyote . MMR motor had about 10 passes and may be 2000 street miles in 2 years ,mostly short trips for street logs and a few 100 mlle trips to a drag strip that lets me run 9’s without hassle . Most passes were at local strip that kicks me out (or gives me warning ) after first or second pass .

Best so far was 10.0 @ 144 but it’s trapped 148 mph .
Only 3 dyno pulls since I swapped heads but no passes

I will surely post up pics if I tear the block down . Probably just going to visually inspect and deck the head and block and reassemble with new head studs. I will keep it as a “spare “

I had the same MMR block in my Hellion car (also GT 350 heads/stock GT cams ) and broke the crank on the dyno testing the GT 350 intake I had just swapped . That motor had about the same miles and dyno passes . It had gone 9.3@152(6R80) and was sure it had an 8 second pass in it .
I saw some big gains over 7000 rpm with the GT 350 intake over the 11-14 intake I had before (the 15-17 intake won’t fit the GT 350 heads )
It was also lifting the heads @17 psi and maybe had valve float but still made 1100 whp .
Crank broke on what was to be the last pull.
I won’t be pulling the motor till I have the replacement ready . I am hopefully but doubt I will be able to salvage any parts .

Will at Whipple is building me a replacement 5.2 block using the updated Gen 2 5.2L block for that car . I will be using either GT 350 heads/MMR springs /GT cams (if an old pair that has scoring can be fixed ) or GT heads with PAC springs .
I am hoping the longer 12 mm head studs will help with the head lift .

 

[AceOne]

Thanks for your expertise .
Crank is coyote . MMR motor had about 10 passes and may be 2000 street miles in 2 years ,mostly short trips for street logs and a few 100 mlle trips to a drag strip that lets me run 9’s without hassle . Most passes were at local strip that kicks me out (or gives me warning ) after first or second pass .

Best so far was 10.0 @ 144 but it’s trapped 148 mph .
Only 3 dyno pulls since I swapped heads but no passes

I will surely post up pics if I tear the block down . Probably just going to visually inspect and deck the head and block and reassemble with new head studs. I will keep it as a “spare “

I had the same MMR block in my Hellion car (also GT 350 heads/stock GT cams ) and broke the crank on the dyno testing the GT 350 intake I had just swapped . That motor had about the same miles and dyno passes . It had gone 9.3@152(6R80) and was sure it had an 8 second pass in it .
I saw some big gains over 7000 rpm with the GT 350 intake over the 11-14 intake I had before (the 15-17 intake won’t fit the GT 350 heads )
It was also lifting the heads @17 psi and maybe had valve float but still made 1100 whp .
Crank broke on what was to be the last pull.
I won’t be pulling the motor till I have the replacement ready . I am hopefully but doubt I will be able to salvage any parts .

Will at Whipple is building me a replacement 5.2 block using the updated Gen 2 5.2L block for that car . I will be using either GT 350 heads/MMR springs /GT cams (if an old pair that has scoring can be fixed ) or GT heads with PAC springs .
I am hoping the longer 12 mm head studs will help with the head lift .

That's impressive! Breaking the crank with turbo is very surprising! Was that block built? I'm curious about internals? What cause it to fail? I want to build one of mine for twins eventually. It may go in my 2005 TX mile/Drag car with a 6R80 conversion.

Any reason not to go to the Voodoo Cams other than cost? They have "better" cam lobes for higher RPM flow... MPR said they really haven't had issues with the heads lifting on the 12mm studs even with the shorter bolts in 5.2 Gen 1 blocks so that should solve that issue for you. I would bet you were getting some valve float if you were pushing 18 psi. The new PAC springs should resolve that also. I'm looking for high RPM stability.

 

[olaosunt]

Thanks man .

I used the “Voodoo” or GT 350 spec cams in the long block going in the KB car .Also has the crank double keyed . I figure the blower car would benefit more from the cams since the gains will be mostly at higher rpm . There was additional expense using those cams as you know since you have to use the OEM GT 350 followers .I also chose to use the upgraded phasers and lifters .
Springs are stock but I was not having valve float in the blower car and RPG says they are 15% stiffer than stock GT cams .
Unfortunately since it started off as 15 block I can only use the 11 mm studs (.L&M could have done a conversion when the block is bare )

I am looking forward to the RPG built block going in the Hellion car . One of the reasons I chose to use the Gen 2 (MA) block is so I can use the 12 mm head studs . If I use the GT 350 heads I will have to use the GT cams due to the wear pattern.
The heads also already have the MMR valve springs but I wonder about them since that’s what is supposed to be in the motor now seeing float (might be a reason to go with the GT heads which will have PAC springs) .

I am not sure if the turbo car will benefit as much from the high lift cams since I won’t be spinning it that high .

Both MMR blocks now in the cars are identical . They were the “1500 hp rated “ blocks with I beams and ARP hardware thought out .
I think the crank failure in the turbo car is related to the ATI damper I had on the car . May be bad installation ?

 

[65Terdlingua]

Thanks guys .
I have just had my CPC 5.2 long block assembled.
I started with a brand new 15 GT block, BES sleeved to 3.7 bore and built with Ross 11.1 pistons and Manley rods .
I am not sure if the pistons were “GT 350 specific”
so hoping I don’t have any PV contact .

Eek. On a build like this, 'hoping' you dont have PTV contact should not even be in the realm of possibility. Every build should have PTV measured, even documented.

 

[Epiphany]

I think the crank failure in the turbo car is related to the ATI damper I had on the car . May be bad installation ?

Did the crank fail at the front snout near the pump? Any photos of it?

 

[olaosunt]

Eek. On a build like this, 'hoping' you dont have PTV contact should not even be in the realm of possibility. Every build should have PTV measured, even documented.

I agree .
I really should have had BES do the long block assembly since they built the block .

I competely forgot about the high lift of the cams when I asked a buddy to help assemble the long block .It does seem like a good idea to have this done with every build regardless of cam lift . Never had it done before on previous blocks with same specs as stock(pistons /cams ) .

Going to look into shipping the block to BES unless I can find some one to do it locally. .
Yes it’s more expense since block will need to be disassembled but better to “pay now than cry later “

 

[olaosunt]

Yes, it’s hard to see but looks like it was after the pump .
I will know more in a few weeks when motor comes out to be replaced .

 

[Offboost]

No disrespect meant but I feel some of you have really derailed Honey-badgers thread and I think you should create your own thread.

 

[olaosunt]

No worries as you are right and I truly apologize.

Should have sent PM’s instead (asking for advice)
Back to regular programming on this awesome build.
Can’t wait to see it all done .

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