Short Block "Kit" Opinions Wanted
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Short Block "Kit" Opinions Wanted
Hi all.
I'm no longer in touch with the machine shop that built or assisted in building several of the engines that have gone through our hands over the last 30years or so. That leaves me in a bit of a quandary regarding the approach to another project.
This one is a Gen 1 383.
I have the heads, hydraulic roller valvetrain (less cam at the moment) and all of the tin. Also the intake, carb and exhaust. That said, those bolt-on/bolt-in bits can be changed to suit. So this isn't really a question about the combination or "what do you think it'll make".
The attached picture is from one of the local speed shops with a "take out" short block. In pieces as I prefer (assembly is not an issue).
Here's the question: Would you take this short block with it's rotating assembly and wring it out at 6000 RPM (maybe 6300 for a measure of overspeed) for let's say what would happen in an open road event? So, several minutes of WOT?
I'm off the opinion that no is the answer.
Cons:
Low end, albeit forged connecting rods with 3/8" hardware.
Externally balanced with the required weighted damper purchased separately.
Cast steel crank.
Pros:
It's relatively inexpensive and would allow me to get back in the game sooner.
I'm a drag racer at heart and with the expected power levels of <500HP/TQ (the current heads and cam should make peak power at ~6000), I can see this package being effective and reliable. But I'd like some insurance for the next possible step.
I know nothing of the machine shop doing the work but the speed shop itself has a solid reputation.
Thoughts? Opinions?
Thanks in advance.
I'm no longer in touch with the machine shop that built or assisted in building several of the engines that have gone through our hands over the last 30years or so. That leaves me in a bit of a quandary regarding the approach to another project.
This one is a Gen 1 383.
I have the heads, hydraulic roller valvetrain (less cam at the moment) and all of the tin. Also the intake, carb and exhaust. That said, those bolt-on/bolt-in bits can be changed to suit. So this isn't really a question about the combination or "what do you think it'll make".
The attached picture is from one of the local speed shops with a "take out" short block. In pieces as I prefer (assembly is not an issue).
Here's the question: Would you take this short block with it's rotating assembly and wring it out at 6000 RPM (maybe 6300 for a measure of overspeed) for let's say what would happen in an open road event? So, several minutes of WOT?
I'm off the opinion that no is the answer.
Cons:
Low end, albeit forged connecting rods with 3/8" hardware.
Externally balanced with the required weighted damper purchased separately.
Cast steel crank.
Pros:
It's relatively inexpensive and would allow me to get back in the game sooner.
I'm a drag racer at heart and with the expected power levels of <500HP/TQ (the current heads and cam should make peak power at ~6000), I can see this package being effective and reliable. But I'd like some insurance for the next possible step.
I know nothing of the machine shop doing the work but the speed shop itself has a solid reputation.
Thoughts? Opinions?
Thanks in advance.
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Kevin
Re: Short Block "Kit" Opinions Wanted
Here’s the scoop on the parts supplied:
All parts SCAT.
Kit no. 1-90305BE
Series 9000 Cast Cranks, Pro Stock I-Beam Connecting Rods with 3/8” Cap Screws (5.7”), Premium Forged Pistons (Icon).
Crank: 9-350-3750-5700
Rods: 2-ICR5700
Pistons: Nothing other than Icon Premium Forged. No info on ring pack.
As I said, this is part of a kit and as for the block machining quality I can't comment but I certainly can determine if it's right.
All parts SCAT.
Kit no. 1-90305BE
Series 9000 Cast Cranks, Pro Stock I-Beam Connecting Rods with 3/8” Cap Screws (5.7”), Premium Forged Pistons (Icon).
Crank: 9-350-3750-5700
Rods: 2-ICR5700
Pistons: Nothing other than Icon Premium Forged. No info on ring pack.
As I said, this is part of a kit and as for the block machining quality I can't comment but I certainly can determine if it's right.
Kevin
Re: Short Block "Kit" Opinions Wanted
What's not to like?
Well assembled SCAT stuff should perform just fine at 6000 RPM. IMHO
Now 7000+..........might increase the pucker factor.
6sally6
Well assembled SCAT stuff should perform just fine at 6000 RPM. IMHO
Now 7000+..........might increase the pucker factor.
6sally6
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Re: Short Block "Kit" Opinions Wanted
I've seen those rods fail over 450hp.
I would much prefer to see the pro I beams with 7/16 bolts in there.
The rest is fine for 550hp/7000rpm.
I would much prefer to see the pro I beams with 7/16 bolts in there.
The rest is fine for 550hp/7000rpm.
Re: Short Block "Kit" Opinions Wanted
True that. But as you indicate, the line is getting close. The drag racing 6000 RPM thing doesn't really concern but what about 5 minutes or more flat out (or nearly so as conditions allow)? I'm not so comfortable with that and why I'm soliciting opinions.
Kevin
Re: Short Block "Kit" Opinions Wanted
That's my thought on the rods as well.KnightEngines wrote: ↑Thu Jun 10, 2021 10:48 pm I've seen those rods fail over 450hp.
I would much prefer to see the pro I beams with 7/16 bolts in there.
The rest is fine for 550hp/7000rpm.
I've heard the cast steel cranks are relatively durable. And 500HP @ 6000 is about the target here.
What's the thought on externally balanced (specifically the balancer)? That's a lot to expect of a crank given that it may be a test of endurance rather than a sprint isn't it?
Kevin
Re: Short Block "Kit" Opinions Wanted
A weighted balancer is part of the kit but it's the stresses that this type of balancing induces is what concerns me. At least that's my understanding. I've got a decent damper now and SFI flexplate but it's an internal balance deal with a 2pc RMS. Plus a pretty good oil pan to go along with it (such is my reasoning for keeping the 2 pc RMS).
Any and all input is appreciated.
Kevin
Re: Short Block "Kit" Opinions Wanted
Thought I'd bump this thinking there may be some additional input.
I don't think the rods care entirely suitable as suggested earlier.
The crank, I'm on the fence about.
The externally balanced deal gives me cause for concern.
I'd still like to pin this thing for minutes on end (supporting parts notwithstanding) and not deal with something borderline that requires an annual teardown and inspection. It's not going to be a race car per se but rather a car that I race.
Thanks.
I don't think the rods care entirely suitable as suggested earlier.
The crank, I'm on the fence about.
The externally balanced deal gives me cause for concern.
I'd still like to pin this thing for minutes on end (supporting parts notwithstanding) and not deal with something borderline that requires an annual teardown and inspection. It's not going to be a race car per se but rather a car that I race.
Thanks.
Kevin
Re: Short Block "Kit" Opinions Wanted
you have listed enough concerns yourself, to look elsewhere.skinny z wrote: ↑Thu Jun 17, 2021 11:47 am Thought I'd bump this thinking there may be some additional input.
I don't think the rods care entirely suitable as suggested earlier.
The crank, I'm on the fence about.
The externally balanced deal gives me cause for concern.
I'd still like to pin this thing for minutes on end (supporting parts notwithstanding) and not deal with something borderline that requires an annual teardown and inspection. It's not going to be a race car per se but rather a car that I race.
Thanks.
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Re: Short Block "Kit" Opinions Wanted
Skinny,skinny z wrote: ↑Thu Jun 10, 2021 4:21 pm Hi all.
I'm no longer in touch with the machine shop that built or assisted in building several of the engines that have gone through our hands over the last 30years or so. That leaves me in a bit of a quandary regarding the approach to another project.
This one is a Gen 1 383.
I have the heads, hydraulic roller valvetrain (less cam at the moment) and all of the tin. Also the intake, carb and exhaust. That said, those bolt-on/bolt-in bits can be changed to suit. So this isn't really a question about the combination or "what do you think it'll make".
The attached picture is from one of the local speed shops with a "take out" short block. In pieces as I prefer (assembly is not an issue).
Here's the question: Would you take this short block with it's rotating assembly and wring it out at 6000 RPM (maybe 6300 for a measure of overspeed) for let's say what would happen in an open road event? So, several minutes of WOT?
I'm off the opinion that no is the answer.
383.png
Cons:
Low end, albeit forged connecting rods with 3/8" hardware.
Externally balanced with the required weighted damper purchased separately.
Cast steel crank.
Pros:
It's relatively inexpensive and would allow me to get back in the game sooner.
I'm a drag racer at heart and with the expected power levels of <500HP/TQ (the current heads and cam should make peak power at ~6000), I can see this package being effective and reliable. But I'd like some insurance for the next possible step.
I know nothing of the machine shop doing the work but the speed shop itself has a solid reputation.
Thoughts? Opinions?
Thanks in advance.
You need to pull the trigger and get it done,we will all die of old age otherwise
steve c
"Pretty don't make power"
"Pretty don't make power"
Re: Short Block "Kit" Opinions Wanted
Question on this... what was the failure mode, what stroke, and at what RPM? Wondering about this, as I have these rods in my 355.KnightEngines wrote: ↑Thu Jun 10, 2021 10:48 pm I've seen those rods fail over 450hp.
I would much prefer to see the pro I beams with 7/16 bolts in there.
The rest is fine for 550hp/7000rpm.
Re: Short Block "Kit" Opinions Wanted
Isn't that the truth! And I'll probably be the first to go.steve cowan wrote: ↑Thu Jun 17, 2021 3:44 pm
Skinny,
You need to pull the trigger and get it done,we will all die of old age otherwise
Covid kind of sucked the life out of the discretionary spending out of which comes the engine budget. Not to mention the whole house renovation I took on three years ago.
At least it's given me plenty of time to research and hang out on ST. Plus my theory data base has grown exponentially.
With any luck, I might be back in the saddle by this time next year (he said for the umpteenth time).
More questions to come.
Kevin
Re: Short Block "Kit" Opinions Wanted
Something I'd like to know myself. I beat the living crap out of stock rods with upgraded hardware but power levels were modest at 400 HP with RPMs less than 6500 with the 355. And that was basically a street/strip car with no endurance punishment dished out.novadude wrote: ↑Thu Jun 17, 2021 3:47 pmQuestion on this... what was the failure mode, what stroke, and at what RPM? Wondering about this, as I have these rods in my 355.KnightEngines wrote: ↑Thu Jun 10, 2021 10:48 pm I've seen those rods fail over 450hp.
I would much prefer to see the pro I beams with 7/16 bolts in there.
The rest is fine for 550hp/7000rpm.
Kevin
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Re: Short Block "Kit" Opinions Wanted
It was a 3.2" stroke 330 cube engine making around 440hp, the beam snapped in the middle when it was hit with a 100 shot of gas.novadude wrote: ↑Thu Jun 17, 2021 3:47 pmQuestion on this... what was the failure mode, what stroke, and at what RPM? Wondering about this, as I have these rods in my 355.KnightEngines wrote: ↑Thu Jun 10, 2021 10:48 pm I've seen those rods fail over 450hp.
I would much prefer to see the pro I beams with 7/16 bolts in there.
The rest is fine for 550hp/7000rpm.
I guess they're good at 450hp & 6500rpm, but not a lot of safety margin.