Short Block "Kit" Opinions Wanted

General engine tech -- Drag Racing to Circle Track

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rfoll
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Re: Short Block "Kit" Opinions Wanted

Post by rfoll »

There was a discussion on here a while back where an engine builder asked about those rods. He freshened an engine for a customer using them every few years, I believe it was a drag car. As it turned out the car owner was regularly hitting them with a 200 shot of nitrous, somewhere in the area of 700 hp total, but the rods showed no signs of deterioration. I have used several sets of them myself in 406 sbc applications with no signs of problems. That being said, none of the engines involves sustained high rpm operation.
So much to do, so little time...
skinny z
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Re: Short Block "Kit" Opinions Wanted

Post by skinny z »

rfoll wrote: Thu Jun 17, 2021 8:13 pm That being said, none of the engines involves sustained high rpm operation.
That bit is appreciated.
It's always benefitted me being involved, such as I am, in drag racing. With modest power you can still be pretty quick and get away with less as I have. As have many others. This isn't to say that a drag engine is a slouch. But when you're in the minors, it's not quite as intense.
That said, I've always admired the Cup cars, the 12/24 hour guys and the open road racers and what they put their machinery through. It really does require a step function change in the approach to engine building.
Or I suppose a guy can just buy a new Vette and call it a day...
Here's hoping, however long it takes before I expire (as has been pointed out!) that I can get in the game to some degree.
Thanks.
Kevin
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Re: Short Block "Kit" Opinions Wanted

Post by rebelyell »

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.
x2 on the 7/16 scat I beams

I'm an a la carte guy ... in general, kits seldom cut the mustard or meet all my needs
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Re: Short Block "Kit" Opinions Wanted

Post by skinny z »

rebelyell wrote: Thu Jun 17, 2021 8:49 pm
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.
x2 on the 7/16 scat I beams
My choice as well if it's strictly a SCAT deal. A point to consider is that those rods, as I understand it, provide clearance for a 3.75" crank and allow for a standard base circle cam. And while on the subject of cranks, a 4340 would also be my preference.
As pointed out, it's becoming apparent that I'm talking myself out of that kit
Kevin
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Re: Short Block "Kit" Opinions Wanted

Post by rfoll »

Do you need the $650 crankshaft more than the $650.
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Re: Short Block "Kit" Opinions Wanted

Post by ProPower engines »

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 tear down and inspection. It's not going to be a race car per se but rather a car that I race.
Thanks.
skinny z wrote: Sat Jun 12, 2021 2:39 pm
skinny z wrote: Fri Jun 11, 2021 11:23 am What's the thought on externally balanced? 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?
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.

Well if you really want the best of both worlds then get you mind into the program.
Any of those kits are just basic low end private label stuff absolute bare bones parts.

The Scat crank is a good option but go with the 6" rod choice. the rods that use a 7/16" cap screw are much stronger and durable, The 3/8 bolt rods go out of round after just the 1st re-torque with a good bearing in them. They are fine for a bone stock build but not something with some power where longevity is wanted.

If you are looking at kits they offer the longer rod and better piston choices as an up sell but the ICON piston is heavy and uses a stock 5/64 ring set. The ring options for 1/16 or 1.5 mm is a better way to go for sealing the bores.
the bearings offered in these kits are always the wrong bearings and 99.99% of the time you wind up with too much clearance for dual purpose use and they are just a bi-metal bearing or single layer bored aluminum bearing sets.
They do offer the KING XP tri-metal bearing upgrade over the SI bearings supplied with the kits at a small up sale cost.

They only offer re-boxed or Hastings std re-builder ring sets again an up sell for the better ring package
But the balance issues of int. versus ext. balance are solved with the longer rod option and no counter weights ring gear/flywheel and or balancer. But several offer Wiseco pistons which are a better choice and lighter weight making the internal balance easier and they can be supplied with a better ring option as well.
The cost of the parts you have for a build is not worth the small cost savings to not get them in a kit new but this is the time to get it perfect so as you say the annual tear down is not needed.

But a cast crank will work but its not forever in a street race application so the better rod and bearing upgrade is where you need to be at among other mentioned parts.

jmo
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skinny z
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Re: Short Block "Kit" Opinions Wanted

Post by skinny z »

rfoll wrote: Fri Jun 18, 2021 12:05 pm Do you need the $650 crankshaft more than the $650.
If either $650 crankshaft gets me a forging then I'm all for it. It's not so much do I need in now but with the cast steel option and my goal of ultimately participating in something like the Sandsprings Challenge in Nebraska, I'm thinking the forging is the way to go.
Kevin
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Re: Short Block "Kit" Opinions Wanted

Post by skinny z »

ProPower engines wrote: Fri Jun 18, 2021 1:31 pm
jmo
Those details are exactly what I'm finding with this "discount" package.
I spoke with the local speed shops SCAT rep and wanted to upgrade. Yes, 6" rods with 7/16ths hardware, forged crank, different choice of piston, etc. Soon the economy went out the window.
This brings me back to my opening statement. I've lost touch with my machine shop of choice (after moving cross country) and those details were easily discussed and sorted out. As far as bearings and ring packs go, that would have been something that I left in their hands knowing their racing history and having had several engines roll through there.
This is probably where my best bet is finding a local shop along those same lines. Tell them what I want to do and go from there. And pricing will probably be better than what I can get on a retail level.
Great reply by the way and much appreciated.
Kevin
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Re: Short Block "Kit" Opinions Wanted

Post by ProPower engines »

A couple issues to consider is piston material either 4032 or 2618.
One material the 2618 is much stronger but nosier then the other in street trim IE mufflers on.
And the other is weight. Some econo pistons while good enough are heavier then others which when it comes to crank choice the bob weight the manufactures targeted for use with it must be considered or your balance guy may end up adding a ton of heavy metal making the crank deal much more then you think it will be.
The other is if its an auto or stick. A flywheel for either should be considered to use an internal balance to make parts replacement easy down the road if needed. Again bob weight needs to be considered so nothing needs to be changed on the flywheel or balancer.
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Re: Short Block "Kit" Opinions Wanted

Post by skinny z »

ProPower engines wrote: Sat Jun 19, 2021 11:43 am A couple issues to consider is piston material either 4032 or 2618.
One material the 2618 is much stronger but nosier then the other in street trim IE mufflers on.
And the other is weight. Some econo pistons while good enough are heavier then others which when it comes to crank choice the bob weight the manufactures targeted for use with it must be considered or your balance guy may end up adding a ton of heavy metal making the crank deal much more then you think it will be.
The other is if its an auto or stick. A flywheel for either should be considered to use an internal balance to make parts replacement easy down the road if needed. Again bob weight needs to be considered so nothing needs to be changed on the flywheel or balancer.
Pistons were one of the items I'm struggling with. I hadn't considered weight other than when I was trying to match the next overbore for the 350 (from .030 to .040) if I were to refresh the 350. With a 383, it's all new so I haven't explored the options other than looking for an appropriate dish. My target is 10:1 to go with 65cc iron heads and .040" PTH clearance. Forged or hypereutectic, I'd say for what I'm doing may not matter in terms of durability. No spray or forced induction planned. Just a simple carb.

The internally balanced is my preference. I've an SFI balancer and flexplate (both neutral from the 2pc RMS 350) and would like to keep the 2 pc if only to reuse the rather pricey Canton road race pan.
Based on info gathered, and in particular what's come of this thread, (thanks to all who chimed in) it's looking more like a mix and match deal rather than a "kit". That's the way I've done it for the several engines that have passed by over the years.
Thanks for the input.
Kevin
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