GT350 Engine Refresh Time!

[honeybadger]

That order isn't quite righ

OK, so let's think about these numbers. First, the Voodoo has a flat crank configured UDUD. So, if we look at each journal, we have the following pairings:

First UD journal pair:

UP #1 - #5: 1166 and 1180 for a total of 2346 going up
DN #2 - #6: 1168 and 1178 for a total of 2346 going down

Then the second pair:

UP #3 - #5: 1177 and 1179 for a total of 2356 going up
DN #4 - #8: 1181 and 1178 for a total of 2359 going down

It sounds pretty balanced to me - am I missing something? There's a 10g imbalance pair to pair and one pair is perfect while the second one is 3g off.

I don't think the logic above quite applies (could be wrong). Here's a video of my rotating assembly



Looking at the video, there are only 2 cylinders at top dead center at a time (and they're on the same side). Wouldn't we want to pair cylinders 1 with 3, 5 with 7, 2 with 4, and 6 with 8? I don't quite have the technical knowledge - hopefully someone can chime in. Definitely curious.

But I don't believe it's quite as simple as your post above. I know firing order/detonation will influence forces a lot too. As a general rule of thumb, most of the builders I've talked to want no more than 1g of variation between all piston assemblies.

That said, you are right that they're paired together to minimize the effects of the different weights. My post above is not to say the OEM balancing/assembly is crap and that every car is going to explode (hell, my own car has served me admirably). Just meant to show some additional data for folks to consider when they're choosing a path for themselves.

FYI - this post was edited for clarity. Want to make sure I am transparent.

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[JAJ]

That's exactly why I said "am I missing something?" in my post. It's just that it occurred to me that maybe the balancing of the moving parts is influenced by which parts are actually moving in the same direction at the same time. What the pairs indicate is that the weights that the crank feels are fairly balanced even if the weights moving in the cylinders are less than perfect, That might matter or it might be an interesting but meaningless coincidence. I figured I'd ask - you've got some real experts here, so I'm curious what they say about it.

 

[honeybadger]

That's exactly why I said "am I missing something?" in my post. It's just that it occurred to me that maybe the balancing of the moving parts is influenced by which parts are actually moving in the same direction at the same time. What the pairs indicate is that the weights that the crank feels are fairly balanced even if the weights moving in the cylinders are less than perfect, That might matter or it might be an interesting but meaningless coincidence. I figured I'd ask - you've got some real experts here, so I'm curious what they say about it.

You caught me before I saved me edits. Made edits to my original post for clarity and soften the tone. No hate/defensiveness intended. Am curious as well. Admittedly, I am neophyte at this level.

 

[JAJ]

You caught me before I saved me edits. Made edits to my original post for clarity and soften the tone. No hate/defensiveness intended. Am curious as well. Admittedly, I am neophyte at this level.

No worries - I didn't even notice. It was Offboost's post #173 about how small imbalances magnify at high RPM that got me thinking about this. His post got me to wondering about the imbalance at each journal, and I was taken by surprise when the pairs at each journal seemed to be balanced when the individual piston-rod combo's were all different weights.

 

[AceOne]

I suggest you re weight the piston assemblies after they are clean. It could be part of the differences. The first set of rods I got from Ford was rounded for easy typing
613
611
610
614
613
611
612
620

I ordered a replacement for the 620 rod since it is very difficult to to take more than 2 or 3 grams off them. Got one that was 612.5 grams. Perfect.

I played around with pins which were almost all 99.0 grams a couple were 99.2 and one was 99.4 grams.

I just looked at my spare rod supply,,,actually have 12.

They each weigh:
609
610
612
612
612
612
613
613
613
613
615
616
so they are pretty consistent with few coming in little light or a little high. The 620 gram one had an offset in the side of the side similar to a casting line misfit. It was thicker in the I beam section for some reason. Probably got through QC on lunch break or something.
Pistons varied from 387.7 to 389.8 grams so average of 388.7 grams +- 1. Great job from Mahle for "production" pistons. I mixed and matched and then did my sanding down to get within a 1.0 gram variance...I had one that that fell an additional .2 grams higher. It was good enough for government work!!

I can see HB variation happening if the parts were matched "poorly" just by tolerances stacking up. Still a niche engine assembled in fairly high volume coming out with +- what 7 or 8 grams??? That's pretty impressive to me.

BTW i just notice HB's are 10 to 24 grams heavier than mine and I didn't remove but 3 grams max to maybe the carbon build up is more than it appears or does it also include the cloth they are sitting on?

I hope this is helpful.
My new block and heads are shipping out tomorrow and ! just got my FR parts in yesterday...going to get started next week if I can get all my other crap done and the garage cleaned up and prepped this weekend.

 

[Nfs1000f]

If I keep reading this thread my head will explode.

 

[AceOne]

I suggest you re weight the piston assemblies after they are clean. It could be part of the differences. The first set of rods I got from Ford was rounded for easy typing
613
611
610
614
613
611
612
620

I ordered a replacement for the 620 rod since it is very difficult to to take more than 2 or 3 grams off them. Got one that was 612.5 grams. Perfect.

I played around with pins which were almost all 99.0 grams a couple were 99.2 and one was 99.4 grams.

I just looked at my spare rod supply,,,actually have 12.

They each weigh:
609
610
612
612
612
612
613
613
613
613
615
616
so they are pretty consistent with few coming in little light or a little high. The 620 gram one had an offset in the side of the side similar to a casting line misfit. It was thicker in the I beam section for some reason. Probably got through QC on lunch break or something.
Pistons varied from 387.7 to 389.8 grams so average of 388.7 grams +- 1. Great job from Mahle for "production" pistons. I mixed and matched and then did my sanding down to get within a 1.0 gram variance...I had one that that fell an additional .2 grams higher. It was good enough for government work!!

I can see HB variation happening if the parts were matched "poorly" just by tolerances stacking up. Still a niche engine assembled in fairly high volume coming out with +- what 7 or 8 grams??? That's pretty impressive to me.

BTW i just notice HB's are 10 to 24 grams heavier than mine and I didn't remove but 3 grams max to maybe the carbon build up is more than it appears or does it also include the cloth they are sitting on?

I hope this is helpful.
My new block and heads are shipping out tomorrow and ! just got my FR parts in yesterday...going to get started next week if I can get all my other crap done and the garage cleaned up and prepped this weekend.

I just noticed the Bearings are still in HB's when he weighed them...that was not in my total weight when I added mine up.

 

[honeybadger]

Alright ya'll. Time to come clean. I've gone ahead with the full rebuild with Tim at MPR Racing Engines. After talking to my wife, I narrowed down my goal for this project given how deep we are in it.

Build the most reliable, bulletproof engine I reasonably can that still utilizes the FPC.

The next morning I called Tim and spoke with him for 15-20 mins about my goal, my intended use of the car/engine, and if this was a realistic idea/goal. He believes the goal is reasonable and has a plan on how to make the FPC ready to take that type of abuse. We spoke at length about some of the challenges of this (harmonics + RPM) and how it ultimately comes down to harmonics, heat and oiling. His plan involves:

• Beefing up the block with sleeves to keep its rigidty when it gets really hot
• Using custom Diamond pistons (forged) and Callies Billet rods to handle the heat and RPM (also a lighter combo than stock)
• Improving the balancing of the rotating assembly so there is less stress/friction at high rpm (which will lower heat)
• Using race-spec coated bearings and piston skirts to better bead off oil, resist hot spots, and improve "slippery-ness"

All the above should create create less heat and friction, which should help with oiling and reduce stress. I'm also going to be installing the FP350S oil cooler and an Accusump Accumulator for pre-oiling and oil starvation prevention. Between these changes and the head work from RGR, we should have an engine that runs smoother, cooler, and is stronger.

I'll continue to be transparent with ya'll. If this blows up in my face and in 3 months I am sitting with a blown engine, I'll be transparent and investigate why.

At the end of the day, someone had to do it first - right?

 

[AceOne]

Alright ya'll. Time to come clean. I've gone ahead with the full rebuild with Tim at MPR Racing Engines. After talking to my wife, I narrowed down my goal for this project given how deep we are in it.

Build the most reliable, bulletproof engine I reasonably can that still utilizes the FPC.

The next morning I called Tim and spoke with him for 15-20 mins about my goal, my intended use of the car/engine, and if this was a realistic idea/goal. He believes the goal is reasonable and has a plan on how to make the FPC ready to take that type of abuse. We spoke at length about some of the challenges of this (harmonics + RPM) and how it ultimately comes down to harmonics, heat and oiling. His plan involves:

• Beefing up the block with sleeves to keep its rigidty when it gets really hot
• Using custom Diamond pistons (forged) and Callies Billet rods to handle the heat and RPM (also a lighter combo than stock)
• Improving the balancing of the rotating assembly so there is less stress/friction at high rpm (which will lower heat)
• Using race-spec coated bearings and piston skirts to better bead off oil, resist hot spots, and improve "slippery-ness"

All the above should create create less heat and friction, which should help with oiling and reduce stress. I'm also going to be installing the FP350S oil cooler and an Accusump Accumulator for pre-oiling and oil starvation prevention. Between these changes and the head work from RGR, we should have an engine that runs smoother, cooler, and is stronger.

I'll continue to be transparent with ya'll. If this blows up in my face and in 3 months I am sitting with a blown engine, I'll be transparent and investigate why.

At the end of the day, someone had to do it first - right?

I know Tim will build you a great motor...but I think it is a bit overkill for the intended application. Just my 2 cents and is probably all its worth. Where are you going to mount the accusump? I have considered it but really don't know where there is enough room in the engine bay. What level of headwork is Rich going to do?

 

[oldbmwfan]

I'm sure you'll end up with a great product. Agree that it's unlikely to blow up in your face, but also that it is probably more than necessary. Still, there is some peace of mind in overkill and I certainly appreciate that (you should see the cage in my track car; it is 40 lbs heavier than it needs to be but I like the extra safety).

I hope it at least doubles the time to your next teardown!

 

[nastang87xx]

I know Tim will build you a great motor...but I think it is a bit overkill for the intended application. Just my 2 cents and is probably all its worth.

Well he has come this far. Ahd sometimes you can't put a price on peace of mind too.

 

[5.2 liters of democracy]

Will you be keeping the stock redline or pushing it up a bit now that the engine build is official?

 

[honeybadger]

I know Tim will build you a great motor...but I think it is a bit overkill for the intended application. Just my 2 cents and is probably all its worth. Where are you going to mount the accusump? I have considered it but really don't know where there is enough room in the engine bay. What level of headwork is Rich going to do?

Overkill is pretty much my middle name. Growing up it was "destruction" and/or "how'd you break it again?"

Rich is porting the heads, doing valve seating work, upgrading the exhaust valves to Ferrea's Super Alloy, titanium retainers, bronze guides, and stiffer PAC Racing springs.

I'm sure you'll end up with a great product. Agree that it's unlikely to blow up in your face, but also that it is probably more than necessary. Still, there is some peace of mind in overkill and I certainly appreciate that (you should see the cage in my track car; it is 40 lbs heavier than it needs to be but I like the extra safety).

I hope it at least doubles the time to your next teardown!

I sure hope so as well. But at the end of the day, if it allows me to relentlessly beat on it without abandon for the same amount of time, I will call it a success.

And can't go overkill with safety IMHO. That's my winter 2020 plan. Cage time!

Well he has come this far. Ahd sometimes you can't put a price on peace of mind too.

Will you be keeping the stock redline or pushing it up a bit now that the engine build is official?

Plan is put on a conservative tune on it from Shaun at AED. So no plans for a higher redline right away. Will take it easy this year and then re-examine next winter. By then there should be cam options available as well

 

[Hack]

Well he has come this far. Ahd sometimes you can't put a price on peace of mind too.

I agree with the peace of mind especially. When you are pushing the car hard, you don't want to have any kind of catastrophic problem.

 

[nastang87xx]

I agree with the peace of mind especially. When you are pushing the car hard, you don't want to have any kind of catastrophic problem.

Yep. If I do heads, I'll just do the OPG at the same time too. And that would also mean cams as well. That is ONLY though because I'd be going that deep into the engine on a disassembly. Otherwise I'd be okay with it as is right now too. It's also about practicality, eh? Do it once, do it right.

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