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Sorry, no metal was chopped off the crank or rods. Only the pistons are going to be reprofiled, I made that kind'a clear.
Now get off my thread! And your 1-7/8 headers are still too big for 400 HP.
It just kills you that this can work. Lol. Didn't you say you were not going to comment on my threads once already? The Mods say I should "ignore you" like so many others do.
Go away, you are an A$$ and a troll. You are a bully too with your speed-boy-toy
You ruined another thread, ya creep.
You should be grateful for my insight, saving you from wasting any more time.....
And if you mean pointing out that you will never be able to "balance" this combination of pieces ruins your thread....you should be grateful, not calling me names!
Yes, I did fail to clarify "spinning."
One can obviously chop chunks of metal off of rods, cranks, and pistons to make virtually any combination of parts "spin".
That's a really simple task.
Grind to fit.
But making a crazy combination work in a running internal engine....that's a bunch tougher.
I already took you to school twice by solving the wheel offset problem and the steering rack torsion bar problem. Same drill crapped all over those too at first but had to admit they work in the end. It's gonna be the same here too. You cant stand if someone else succeeds where you have failed
You crapped on Colin and his centering spring which I have and has been fine for years. I'm sure there are others. The list goes on and on. You're not the only intelligent life in the 928 community. You biggest claim to fame lately is a gasket ! WOW No-one else could have ever though of that?
Last edited by icsamerica; Mar 17, 2022 at 02:07 AM.
You should be grateful for my insight, saving you from wasting any more time.....
And if you mean pointing out that you will never be able to "balance" this combination of pieces ruins your thread....you should be grateful, not calling me names!
Still not grateful. It was already rough balanced by Scat. We did the whole bob weight thing. It will be final balanced local. Again, you DONT KNOW WHAT I ORDERED FROM SCAT
First it wont turn, it turns, now it wont balance, it was rough balanced already. Go re-watch the video, you can see where is was drilled for balance already. Did you ever stop to consider short rods motors are easier to balance because short rods are a bit lighter. There is also this thing called Mallory. What's next? Keep trying, ya creep.
Keep going, you're just exposing yourself as the fraud you are.
balance ?
Last edited by icsamerica; Mar 17, 2022 at 02:26 AM.
... It's a custom crank. All of my own spec but typical in the sense that I'm sure others have come to the same conclusions, 96mm, stroke, 141mm rods and, 100MM pistons . So it's going to be a 6.0 L / 6000 RPM max and torque focused. Rod ratio will be an acceptable to me 1.48. The high mid cycle piston speeds coupled with the good mid lift flow of the heads should make this engine pull hard from 3500 to 5500. I toyed with the idea of a shorter stroke, longer rod and larger bore pistons but around here no one can or is willing to bore these blocks. Then there is the piston coating / scuffing issue, it's a bit of a mystery to most. Some say coatings work and some says it doesn't last so stock pistons and bores will remain. Alusil refinishing is a dead art, like cutting rotors, and TV repair so I've chosen what can be done over what I usually do in the SBC / LS realm. This has been a long time coming, the block sat for a long while at a machine shop who said they would / could bore it to 104mm (968 piston size) but the block and parts just sat there for 9 months, untouched, after that my calls to other machine shops in the area went un-returned so stock bore it will be, and that's fine for the intended purposes.
In any case this is how I see it. The stock piston are quite good, the stock rods are far heavier than they need to be, and the OE crank has oiling issues. So the path of least resistance and opportunity align with a redesigned crank and modern and far lighter connecting rods topped with the OE piston.
Folks, if I had any common sense I would seriously avoid stepping into this conversation. But I think we need to respect the constraints posited in post #1 here: Can't bore the block and no one trusts the piston coatings, so stock 100mm pistons, custom crank, custom rods, and a longer stroke. The result fits the stated goals: more torque at a lower RPM range than stock. Not my choice, but also not my engine.
ICS, I don't know your car but if this is an automatic transmission for street use then this might be as good a choice as any. The problem is that whenever you have to shift to a higher gear, you lose torque at the wheels-- that's just the nature of gears. But when the torque falls off the cliff (post 22) you've got to shift.
Personally, I am quite fond of the GT character: the longer you keep your foot in it, the faster it wants to go. That, to me, is what these cars are about. (This is not a casual statement: We've put 100K miles on an S4, 150K on a GT, and a bit on a GTS-- all 5-speeds. The S4 runs great but runs out of steam, the GT is a scalded cat, and the GTS was like driving into a pillow at higher RPMs).
If peak power at 5000 rpm is the Holy Grail for you, then what you are doing is fine. If it is an auto then set it up to shift at 5500 and you will be good. But understand that no one ever said that short rods are good, you are just giving away torque. And long stroke / small bore is not what most folks would choose.
When Porsche built a 3.0L 4-cylinder (half a 6L 928 motor), they chose an 88mm stroke and a 104mm bore, with a 150mm rod and a rod/stroke ratio of 1.70. That's pretty far from what you are spec'ing. There are folks that know how to bore and finish alusil blocks, and 104mm pistons are available. You don't have to make design choices just because you want to be contrary.
Folks, if I had any common sense I would seriously avoid stepping into this conversation. But I think we need to respect the constraints posited in post #1 here: Can't bore the block and no one trusts the piston coatings, so stock 100mm pistons, custom crank, custom rods, and a longer stroke. The result fits the stated goals: more torque at a lower RPM range than stock. Not my choice, but also not my engine.
ICS, I don't know your car but if this is an automatic transmission for street use then this might be as good a choice as any. The problem is that whenever you have to shift to a higher gear, you lose torque at the wheels-- that's just the nature of gears. But when the torque falls off the cliff (post 22) you've got to shift.
Personally, I am quite fond of the GT character: the longer you keep your foot in it, the faster it wants to go. That, to me, is what these cars are about. (This is not a casual statement: We've put 100K miles on an S4, 150K on a GT, and a bit on a GTS-- all 5-speeds. The S4 runs great but runs out of steam, the GT is a scalded cat, and the GTS was like driving into a pillow at higher RPMs).
If peak power at 5000 rpm is the Holy Grail for you, then what you are doing is fine. If it is an auto then set it up to shift at 5500 and you will be good. But understand that no one ever said that short rods are good, you are just giving away torque. And long stroke / small bore is not what most folks would choose.
When Porsche built a 3.0L 4-cylinder (half a 6L 928 motor), they chose an 88mm stroke and a 104mm bore, with a 150mm rod and a rod/stroke ratio of 1.70. That's pretty far from what you are spec'ing. There are folks that know how to bore and finish alusil blocks, and 104mm pistons are available. You don't have to make design choices just because you want to be contrary.
All fair points but please consider I'll end up with the same rod ratio as a BMW M3, 1.48. By all accounts that's a fantastic engine. The engine sim shows the limit for the HP is head flow, not rod length.
Look and listen, instead of tossing out personal insults.
When you add stroke to a crankshaft, you need to add more counterweight to offset the rod journals being further out from center....not less!
When I build an engine with as big a counterweight as I can get with a 6"(+) light weight connecting rod and a super light piston/pin (under 500 grams), I'm having to add 6-8 slugs of Mallory, to be able to balance these engines.
Think about what you are trying to do.
Reduced counterweights for a short connecting rod. Super heavy stock piston.
Yeah, the rod is shorter, but the mass on the rod throw (which you need to counterbalance) isn't going to be reduced (unless you use Titanium rods.)
Relax dude...it's an engine discussion, not a bar fight.
Look and listen, instead of tossing out personal insults.
When you add stroke to a crankshaft, you need to add more counterweight to offset the rod journals being further out from center....not less!
When I build an engine with as big a counterweight as I can get with a 6"(+) light weight connecting rod and a super light piston/pin (under 500 grams), I'm having to add 6-8 slugs of Mallory, to be able to balance these engines.
Think about what you are trying to do.
Reduced counterweights for a short connecting rod. Super heavy stock piston.
Yeah, the rod is shorter, but the mass on the rod throw (which you need to counterbalance) isn't going to be reduced (unless you use Titanium rods.)
Relax dude...it's an engine discussion, not a bar fight.
Again. It was already rough balanced. Mallory is not a crime. Pins are drilled, 8 counter weights. OE crank only has 6. Big end of rods are far lighter than OE. I'm using rods that are good to 450HP, I'll be well shy of that. This was considered and accounted for long ago, it's settled, a dead issue. All these techniques are news to you?
Pins are drill to save weight to aid in balancing.
Last edited by icsamerica; Mar 17, 2022 at 04:27 AM.
Again. It was already rough balanced. Mallory is not a crime. Pins are drilled, 8 counter weights. OE crank only has 6. Big end of rods are far lighter than OE. I'm using rods that are good to 450HP, I'll be well shy of that. This was considered and accounted for long ago, it's settled, a dead issue. All these techniques are news to you?
Pins are drill to save weight to aid in balancing.
You can get 42 grams off the original wrist pin in order to facilitate crankshaft balancing.
Åke
All fair points but please consider I'll end up with the same rod ratio as a BMW M3, 1.48. By all accounts that's a fantastic engine. The engine sim shows the limit for the HP is head flow, not rod length.
Head flow is not the limit for good engine performance. You can hardly find an engine having more intake port air flow. The intake manifold is a bottleneck.
Åke
That is SWEET info. Thanks, I didnt think about the wrist pin but Its good to know I can loose some weight there IF needed. To continue the thought to the extreme... One could switch over to pressed on rod pins then a 58mm LS wrist pin can be used. At 90 grams and less than 75$ for a set of 8 its something to think about. Not sure I'd want to go back to pressed pins but, if weight was paramount then it's something to consider.
Last edited by icsamerica; Mar 17, 2022 at 10:31 AM.
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