To sleeve or not to sleeve a Voodoo

Imma Sssnaake

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As everybody knows, voodoos love boost but tend to be living on borrowed time with the stock bottom end (yes, i know your brother’s friend’s uncle has one that’s been boosted on a SBE for years without a problem). But most people who build motors for their boosted Shelbys go ahead and sleeve the motor when doing rods/pistons, but is it really necessary? Yes, the walls are thinner than a coyote but has anybody seen a boosted voodoo have failures due to the block itself? All the blown engines that I have seen have been because of a rod or piston failure, never the crank or the block. So if someone where to keep power under 1000 tire, wouldn’t a set of rods/pistons designed for boost and some ARP studding be a reliable setup?

 

EFI

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Honestly, under 1000 and not beat on constantly should be fine SBE. The Voodoo already has forged pistons, the rods are solid so you shouldn't have any issues as long as tuning and fueling are on point.
 

Niz55

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drop a gen2 5.0 in it and save your stock motor.
 

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Going to answer your question with some additional context.

(5) things to keep in mind with boosting a Voodoo:
  1. The Voodoo is high compression. As a result, adding boost to it will add a lot more pressure and stress to the internals than a similar lower compression engine. This goes to point #2.
  2. The engine is forged, but it is bean counter forged. The OEM parts are good, but they're not superior quality. I'd say the QC is hit and miss enough that risking high compression AND boost is beyond an acceptable level of risk.
  3. This engine is ultimately built with Detroit tolerances. Bores might be a few thousands off, piston assemblies weigh a few grams more, etc. Mix these with high compression, boost, and high RPM and you're adding even more stress and heat to the motor.
  4. The Voodoo is a HUGE bitch with crankcase pressure and PCV due to the FPC and block design. All the above just makes it worse and, therefore, increasing the problems.
  5. The Voodoo has a custom flywheel and harmonic balancer specifically designed to handle the secondary vibrations created by the FPC. I wouldn't recommend changing either. People have snapped crank snouts off with aftermarket balancers. I personally know a few. This rules out superchargers, IMHO.
All this means you have a rotating assembly that isn't optimized for boost, creating tons of friction and heat, building tons of stress, and spinning at insane speeds. It's a HUGE uphill battle.

Sleeving the block allows you to fix those bore tolerances and reduce friction. Because you can't hone the OEM block due to the plasma arc coating, it's a no brainer for most.
 

honeybadger

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Yeah but then i’d lose displacement and the whole reason for buying a GT350, that flat plane crank..
Just for additional context, most engine builders I know would MUCH rather build a coyote for boost than a Voodoo. They can make the same power with much less stress.
 
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Imma Sssnaake

Imma Sssnaake

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Going to answer your question with some additional context.

(5) things to keep in mind with boosting a Voodoo:
  1. The Voodoo is high compression. As a result, adding boost to it will add a lot more pressure and stress to the internals than a similar lower compression engine. This goes to point #2.
  2. The engine is forged, but it is bean counter forged. The OEM parts are good, but they're not superior quality. I'd say the QC is hit and miss enough that risking high compression AND boost is beyond an acceptable level of risk.
  3. This engine is ultimately built with Detroit tolerances. Bores might be a few thousands off, piston assemblies weigh a few grams more, etc. Mix these with high compression, boost, and high RPM and you're adding even more stress and heat to the motor.
  4. The Voodoo is a HUGE bitch with crankcase pressure and PCV due to the FPC and block design. All the above just makes it worse and, therefore, increasing the problems.
  5. The Voodoo has a custom flywheel and harmonic balancer specifically designed to handle the secondary vibrations created by the FPC. I wouldn't recommend changing either. People have snapped crank snouts off with aftermarket balancers. I personally know a few. This rules out superchargers, IMHO.
All this means you have a rotating assembly that isn't optimized for boost, creating tons of friction and heat, building tons of stress, and spinning at insane speeds. It's a HUGE uphill battle.

Sleeving the block allows you to fix those bore tolerances and reduce friction. Because you can't hone the OEM block due to the plasma arc coating, it's a no brainer for most.
Thank you for the response, so it seems besides all the harmonic issues that the compression is the only danger to the block after doing rods/pistons. What if you chose to lower the compression when picking out pistons? So a lower compression rod/piston combo with say twin turbos to avoid messing with the harmonic balancer, could that be a safe setup?
 

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Coyote engine has the same comp ratio as the voodoo now... even the previous gen was close. Most engine builders like high cr as long as fueling isn't an issue. I've talked to RPG engines several times and they prefer boosting the voodoo at its factory cr or higher depending on application. if you're building an engine, def sleeve it and spend the money on balance/blueprint.
 

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It was mentioned the GT350 pistons are forged. Are the connecting rods?

What is forged, and what isn't that could be?

Does it vary by year?

thx
 

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Forged is when a block of the material is literally hammered into a mold or block and then it’s CNC machined to get finished. If it’s cast the metal is melted and flowed into a mold. When you forge a part it’s much stronger since the molecules of the alloy are literally forced closer together. There are variations of all these processes and I’m sure the resident metallurgy experts will chime in. I know we have a few in here.
 

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Forged is when a block of the material is literally hammered into a mold or block and then it’s CNC machined to get finished. If it’s cast the metal is melted and flowed into a mold. When you forge a part it’s much stronger since the molecules of the alloy are literally forced closer together. There are variations of all these processes and I’m sure the resident metallurgy experts will chime in. I know we have a few in here.
Thank you!

But what I mean is, what parts of the motor is forged? For example, are the connecting rods also forged, or just the pistons?

thx!
 

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Thank you!

But what I mean is, what parts of the motor is forged? For example, are the connecting rods also forged, or just the pistons?

thx!
I had my stock voodoo engine torn down by RPG racing after it failed (with Whipple ).
Failure was due to a couple of bent rods . He also found evidence of head lift so that could have contributed but the rods are definitely a weak point and are not “forged” at least like the typical aftermarket rod .
I had that block sleeved with the rebuild - Manley H rods (voodoo specific ) and Diamond pistons . Some minor head work - upgraded springs /new valve seals and Head studs .So far so good with 15 psi this time around (and you can keep the stock balancer with the whipple )

The stock pistons are high quality/forged and made by Mahle .They also sell them as a “drop in replacement “
http://www.us.mahle.com/media/usa/motorsports/ford-5-2l-drop-in-2020-web.pdf
I am building at least one spare (non sleeved ) engine(got the entire engine cheap ) just swapping the rods and keeping the stock pistons.

if you plan to add boost and will be starting from scratch, the Gen 2/3 voodoo block is definitely what to use as a foundation . It’s the same block in the GT 500 and it definitely “beefier “ . Also uses the longer 12 mm Head studs /bolts so less chance of head lift .
Of course if you have a 19 + GT350 then you already have the block .
Sleeving the block of course is still the strongest option (and you get to address other issues at the same time) but sleeving also has its risks as they can drop causing head gasket sealing issues .
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