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I'm planning out a build of a 532 cubic inch big block for a project, gonna be twin turbo, sequential fuel injected, coil near plug ignition, somewhat normal stuff for serious performance. The weird stuff starts here, I decided to go with a flat plane crankshaft, long aluminum rods, and short pistons so I can spin this thing higher than I could otherwise, maybe even as high as 9,000 rpm, not sure yet. For the proper quench I want, the static compression I'm eyeing, and the RPM I'm looking for I'm gonna use 6.7" aluminum rods and 1.1" tall forged aluminum pistons, netting me 0.021" quench due to the head gasket thickness. What issues will I run into? First thing that comes to mind is with that piston height the wrist pin is going to start getting into the oil control ring, would I see issues with oil consumption? If the pin is moved down towards the bottom would I have stress issues that could/would lead to cracking and breaking of pistons over time? On the crank I'm thinking an Up-Down-Down-Up rod journal arrangement so as to have a firing order closer to that of an LS, however I have no clue what the bob weight on the crank will be and in the response email I got that was one of the things they'll need, is this just the weight of the crankshaft?

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The pistons should be built to handle the stress to a point......I’m worried about the 9k spin over and over something will give sooner than later. Spark plugs are the only thing that stands out to me?

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The pistons should be built to handle the stress to a point......I’m worried about the 9k spin over and over something will give sooner than later. Spark plugs are the only thing that stands out to me?
I don't think in street driving I'd get to 9k with the gear ratios in the tranny, the diff ratio, the tire height, and the design of the car. It's not going in a trifive, this was just the first forum I found on Tapatalk that was close to being right to discuss this topic

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That’s a pretty radical build. I wouldn’t consider that any more than a temporary motor on the street. Sounds pretty expensive also. It’s easy to tell that you want to do it no matter what anybody else says, so I wish you luck, and let us know how it works out please.

On the other hand, a 532 built in a more traditional way is still going to have power galore. The modified LS and blown BB guys will give you a run for sure, but most others will be done for.
 

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Discussion Starter · #5 ·
That’s a pretty radical build. I wouldn’t consider that any more than a temporary motor on the street. Sounds pretty expensive also. It’s easy to tell that you want to do it no matter what anybody else says, so I wish you luck, and let us know how it works out please.

On the other hand, a 532 built in a more traditional way is still going to have power galore. The modified LS guys will give you a run, but most others will be done for.
I don't think the LS crowd would stand a chance, the rest of the powertrain is going to be A RaceTech 6XD sequential manual dogbox in the all wheel drive transaxle, when it's released, with an MME paddle shift kit and the appropriate Winters Quick Change differentials that they're designing it to be coupled with. The turbos on this 532 are Precision made mirror image 76MM units, in the twin config they're capable of supporting 2,600 horsepower, however that doesn't say what engine that's on so for all I know it'll do 3,000. I think the diff ratios I picked may be a little too low numerically but given it's gonna have some decent aero (a front splitter that's advertised to provide over a ton of downforce at 150+, a rather aggressive wing, and a rear diffuser made by the same people as the splitter) it'll be fine, and if not it's easy enough to change on the Winters

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Oh ok, that straightens things out a bunch. I had thought you were planning to run the quarter and some street use. Kinda sounds now like a mud bog truck, or a rock climber. At any rate what you are planning should kill every living thing on whatever course you’re going to run. LOL!
 

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Discussion Starter · #7 ·
Oh ok, that straightens things out a bunch. I had thought you were planning to run the quarter and some street use. Kinda sounds now like a mud bog truck, or a rock climber. At any rate what you are planning should kill every living thing on whatever course you’re going to run. LOL!
It's not a mud truck, it's gonna be a mid engine car, I got the idea one day with one of the previous truck driving job that it'd be cool to try and do something with a heavy duty truck engine and tranny like this and then I realized that was stupid, I moved on to a 598, realized I could get a longer life out of the engine with a shorter stroke, and so I kept the 4.6" bore but dropped to a 4" stoke, hence the 532

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Discussion Starter · #8 ·
If I were to build a mud truck or an off road rig I'd do diesel, maybe a 6v53 Detroit, a 5.9 Cummins, or to be weird a DT466

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Ok, that’s getting a little closer. A mid engine car to do what? Are you planning to build a whole body, or is it for an existing car?
 

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Ok, that’s getting a little closer. A mid engine car to do what? Are you planning to build a whole body, or is it for an existing car?
I'm gonna be building the whole thing, I'm not sure the exact way it'll be done but I do know what I'm going for

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Am starting to feel that I got snookered into this. An interesting build question though. Adios.
 

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your rotating assy has 1 serious issue. the .021 quench is way too small with an aluminum rod. the rod grows as it heats up and stretches as it rotates with a piston on it. the piston grows too. with a quench of .021" it will probably have the pistons smacking the heads before it reaches full operating temp. another thing to consider is that with a bearing clearance of .0035" that reduces the quench down to about .0175" at tdc on deceleration. This would happen even with an aluminum block as it will grow less due to mass and steel cylinder liners. just my thoughts
 

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your rotating assy has 1 serious issue. the .021 quench is way too small with an aluminum rod. the rod grows as it heats up and stretches as it rotates with a piston on it. the piston grows too. with a quench of .021" it will probably have the pistons smacking the heads before it reaches full operating temp. another thing to consider is that with a bearing clearance of .0035" that reduces the quench down to about .0175" at tdc on deceleration. This would happen even with an aluminum block as it will grow less due to mass and steel cylinder liners. just my thoughts
This whole thing sounds like to me that you are getting your crank stroked!
 

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The radical rod ratio and pin height started raising alarms. Not impossible but could be problematic even with a talk deck Big M block. Tried to draw him out with the mud bog and crawler question just to get more application info, but after all that he still wouldn’t come forth. It’s another case of troll BS I think. A fun conversation though.
 

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Discussion Starter · #15 ·
I'll accept that I'm not entirely sure the point of this but it's going to be done. What's the quench height I'd want so as to avoid piston contact with the valves?

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your rotating assy has 1 serious issue. the .021 quench is way too small with an aluminum rod. the rod grows as it heats up and stretches as it rotates with a piston on it. the piston grows too. with a quench of .021" it will probably have the pistons smacking the heads before it reaches full operating temp. another thing to consider is that with a bearing clearance of .0035" that reduces the quench down to about .0175" at tdc on deceleration. This would happen even with an aluminum block as it will grow less due to mass and steel cylinder liners. just my thoughts
hotrodg726 beat me to it. That .021 quench simply will not work with aluminum rods, especially at 9 grand. .035 to .040 is the norm for steel rods, so yours should be around .060. Really though, with twin turbos, I don't think a tight quench is really all that important anyway.
 

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Discussion Starter · #17 ·
hotrodg726 beat me to it. That .021 quench simply will not work with aluminum rods, especially at 9 grand. .035 to .040 is the norm for steel rods, so yours should be around .060. Really though, with twin turbos, I don't think a tight quench is really all that important anyway.
Thanks for that, knowing that I think then I'll go with a slightly shorter rod, around 6.65" that way between the head gasket and the deck clearance I hit around that 0.060"

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What's the quench height I'd want so as to avoid piston contact with the valves?

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QUENCH HIGHT HAS NOTHING TO DO WITH PISTON TO VALVE CLEARENCE it is the distance from the top of piston to the flat quench area of the head at the block deck.
 

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Discussion Starter · #19 ·
QUENCH HIGHT HAS NOTHING TO DO WITH PISTON TO VALVE CLEARENCE it is the distance from the top of piston to the flat quench area of the head at the block deck.
I understand that. It was mentioned that with a 0.021" quench the pistons would hit the head because of rod and piston growth due to heat, I phrased it the way I did because of that.

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