Trw l2352f piston ,destroke only? - Chevelle Tech
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post #1 of 13 (permalink) Old Jan 15th, 10, 12:41 PM Thread Starter
chris
 
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Trw l2352f piston ,destroke only?

I have a set of TRW/Speed pro L352F pistons and all the info I find for these at Flatlanders indicates for a 400 ci with a 350 crank/5.7 rods. This makes -for a destroking the 400. My question is I do not want to "destroke" this 400, but assume this piston cannot be used in a 400 ci with the stock 375 stroke crank?
Does anyone know where I can fine information for this piston indicating it can be used on a 375 crank in a 400 ci (going .030 over 4.155 making a 406)? Thanks

Last edited by hopalong; Jan 15th, 10 at 1:18 PM. Reason: incorrect piston #
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post #2 of 13 (permalink) Old Jan 15th, 10, 1:02 PM
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Re: Trw l2253f piston ,destroke only?

Quote:
Originally Posted by hopalong View Post
I have a set of TRW/Speed pro L2253F pistons and all the info I find for these at Flatlanders indicates for a 400 ci with a 350 crank/5.7 rods. This makes -for a destroking the 400. My question is I do not want to "destroke" this 400, but assume this piston cannot be used in a 400 ci with the stock 375 stroke crank?
Does anyone know where I can fine information for this piston indicating it can be used on a 375 crank in a 400 ci (going .030 over 4.155 making a 406)? Thanks
=
Do you mean the 2352?
It would help if you added the specs, especially the c/h of the piston so we do not have to go look it up but if that is the piston it has a 1.555c/h so it will not work except with the stock 400 rod & then you have to watch the counterweight clearance unless it is a stock crank
Also unless you already have the pistons there are many others I would choose before the Speedpro
And don't drop that sucker on you toe

Mike (Wolfplace)
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post #3 of 13 (permalink) Old Jan 15th, 10, 1:07 PM
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Re: Trw l2253f piston ,destroke only?

Quote:
Originally Posted by Wolfplace View Post
Also unless you already have the pistons there are many others I would choose before the Speedpro
And don't drop that sucker on you toe

George Kettler
o 70 Elky 496 build with #074 AL heads is done race weight should be 3895# with the AL heads and the thinner front race rubber. New combo, no times
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post #4 of 13 (permalink) Old Jan 15th, 10, 1:22 PM Thread Starter
chris
 
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Re: Trw l2352f piston ,destroke only?

Yeah it is a L2352F piston. Stock 400 crank (3.75 stroke). So the 5.7 rod will not work due to the stroke?
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post #5 of 13 (permalink) Old Jan 15th, 10, 1:35 PM
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Re: Trw l2352f piston ,destroke only?

350 and 400 both use the same compression height. To make up the difference of the larger stroke in the 400, GM went to a shorter rod.

Those pistons will work with either a 350 crank and 5.7 rods OR a 400 crank and 5.565 rods.

Ray
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post #6 of 13 (permalink) Old Jan 15th, 10, 1:35 PM
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Re: Trw l2352f piston ,destroke only?

Quote:
Originally Posted by hopalong View Post
Yeah it is a L2352F piston. Stock 400 crank (3.75 stroke). So the 5.7 rod will not work due to the stroke?
Correct unless you want to run a really thick head gasket
Piston will be an eighth inch out of the bore give or take

Goes like so
1/2 stroke + rod length + c/h
3.75/2=1.875 + 5.7 + 1.555 = 9.13
9.13-9.025 (undecked nominal height of a small block) = .105 above the deck

BTW, that 9.025" is what GM says it is supposed to be not necessarily what it is,, they vary a lot

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post #7 of 13 (permalink) Old Jan 15th, 10, 1:50 PM
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Re: Trw l2352f piston ,destroke only?

Quote:
Originally Posted by Wolfplace View Post
=
Do you mean the 2352?
It would help if you added the specs, especially the c/h of the piston so we do not have to go look it up but if that is the piston it has a 1.555c/h so it will not work except with the stock 400 rod & then you have to watch the counterweight clearance unless it is a stock crank
Also unless you already have the pistons there are many others I would choose before the Speedpro
And don't drop that sucker on you toe
600gram rock there

Have had a few of them lightened, now I wonder why we messed with them lol

Mike, when did they stop making the proper rings for the OLD OLD TRW's? Remember when they cut the grooves for ~.230" depth etc? I believe the rings were what, .220"

I still have some of the old pistons with the "DEEP" ring groove , they work fair with a .183" D wall today

Quote:
Originally Posted by hopalong View Post
Yeah it is a L2352F piston. Stock 400 crank (3.75 stroke). So the 5.7 rod will not work due to the stroke?
You didnt say what your deck height is, but it really doesnt matter at this second

Here is some information to "help" you with this,,

Stroke/2 = X + compression height (CH) + rod length = deck height of piston

So lets look at your CH, rod length of 5.7" and stroke

3.75" stroke /2 = 1.875" + 5.7" rod length + 1.555" ch = 9.130"
So the problem here is the spec for small block with no milling is 9.025" , so the piston would be .105" out of the hole

Now lets look at it with the 400 rod and 3.75" stroke
3.75" /2 = 1.875" + 5.565" + 1.555" ch = 8.995"
So if your block was decked to 9" deck height, your piston would be .005" in the hole, it can get hairy as Mike AKA Wolfplace has pointed out

Do you have a budget to get new pistons? You can get both Probe and Keith Black for a very reasonable cost for the 3.75" stroke and 5.565", 5.7" or 6" rods

An example would be the Keith Black 2618 Premium Forged now know as KB Icon and Probe Sportsman Race Series pistons (I dont know what compression you want so im just gonna throw two examples out there)

Probe 12338
4.0cc flat top
1.425" compression height
507grams/118gram pin
5.7" rod length

KB751 flat top
4.8cc flat top
1.433" compression height
517grams/132gram pin
5.7" rod length

If you can go 6" rods, I would rather have 6" rods but thats just my opinion


Probe 12339
4.0cc flat top
1.125" compression height
450grams/118gram pin
6.0" rod length

KB755 flat top
4.8cc
1.133" compression height
449grams/132gram pin
6.0" rod length

With KB755 I would upgrade to 107gram Tool Steel pin, just to get some weight out of it so your not using a 132gram pin, the 118gram pin is fine in the Probe. If street the 132gram pin in the KB is fine, I just like the pins to be below 120grams BUT strength is more important in my opinion
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post #8 of 13 (permalink) Old Jan 15th, 10, 1:52 PM
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Re: Trw l2352f piston ,destroke only?

Quote:
Originally Posted by Wolfplace View Post
Correct unless you want to run a really thick head gasket
Piston will be an eighth inch out of the bore give or take

Goes like so
1/2 stroke + rod length + c/h
3.75/2=1.875 + 5.7 + 1.555 = 9.13
9.13-9.025 (undecked nominal height of a small block) = .105 above the deck

BTW, that 9.025" is what GM says it is supposed to be not necessarily what it is,, they vary a lot
Started on the quote at 1:25 then had to run, You tree'd me
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post #9 of 13 (permalink) Old Jan 15th, 10, 3:11 PM Thread Starter
chris
 
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Re: Trw l2352f piston ,destroke only?

Base on not wanting to go with any other pistons for now and using these with the stock 400 rods and 400 crank and with a 9.025 deck .What would be the compression with these L2352F .030 pistons using 64cc heads?
The compression data at Flatlanders shows this piston .030 over is based on a 350 crank and 5.7 rods in a 400 block.
Thanks
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post #10 of 13 (permalink) Old Jan 15th, 10, 3:29 PM
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Re: Trw l2352f piston ,destroke only?

Quote:
9.13-9.025 (undecked nominal height of a small block) = .105 above the deck
Your piston will stick above the deck by 0.105" so assuming you have/or can find a head gasket that's 0.145" -0.150" thick ,you'd be around 9.2c/r.
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post #11 of 13 (permalink) Old Jan 15th, 10, 3:43 PM Thread Starter
chris
 
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Re: Trw l2352f piston ,destroke only?

Quote:
Originally Posted by Mike View Post
Your piston will stick above the deck by 0.105" so assuming you have/or can find a head gasket that's 0.145" -0.150" thick ,you'd be around 9.2c/r.
You are refering to of course using the piston with a 5.7 rod . With the stock 5.56 rod it would be at 8.99, below deck

Using the 5.7 it would be at above the deck
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post #12 of 13 (permalink) Old Jan 15th, 10, 3:59 PM
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Re: Trw l2352f piston ,destroke only?

Without knowing the cc's of the piston head ,head gasket thickness you want can't calculate it but you can
http://www.csgnetwork.com/compcalc.html
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post #13 of 13 (permalink) Old Jan 15th, 10, 4:34 PM
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Dave 383 now
 
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Re: Trw l2352f piston ,destroke only?

64cc head approx 9.9:1
76cc head approx 8.9:1

So as mentioned to use your 400 (3.75) crank with those pistons, you need to use 400 (5.565) rods.

Dave
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