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Boring for stroker without a torque plate?


HizAndHerz

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I've called several performance machines shops in the Houston area and nobody has a torque plate for an L28 block. The shops included Westside Performance and G&G in Tomball, others shops didn't know what an L28 was.

 

G&G was reluctant to try boring 0.120" over without a deck plate. Westside said it would probably be okay without a deck plate as long as the block was sonic tested.

 

So, how safe do y'all think it is to bore that much without a deck plate? Can a deck plate be rented? Can one be made from scratch?

 

Thanks in advance for any suggestions. It's taken me over a year to collect parts for this stroker motor project and now it looks like I might not be able to find anyone to do the machine work :-(

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Yeah, it would be great if the L28 machining gurus here could shed some light on the availability of torque plates.

 

Heck, I had the crazy idea of hacking oversized cylinder holes in a junk head, then have it milled flat. Shablam! Poor man's L28 torque plate! No?

 

Another hairbrained idea: have cylinders bored within a few 1000ths of the target, then bolt on a head and hone the rest of the way from the crank side. Probably not practical or effective, but hairbrained, yes. Signs of desperation!

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"Shablam! Poor man's L28 torque plate! No?"

 

No...

Using a 4" Slab of Aluminum you can punch out a deck plate on a Bridgeport manually in short order. A junk head cut up would not give you the same rigidity as the deck plate.

 

Back to topic, the boring plate discussion was covered previously, lots of discussion.

 

I've seen all sorts of high performance engines built using stone-age implements (can you guys remember a 'block top' boring bar?) so while there is 'state of the art' you have to ask 'am I competing in F1, or driving on the street'? What is unacceptable for top ranks of competition is perfectly acceptable for daily drivers with even more than occasional track use.

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Ask if they have an RB torque plate if they do have them use this as they share the same bore spacing and head bolt locations as the L6 series (no don't try and install a RB head onto a L bottom end the oil and water galleries are too different and then there is the belt vs chain issue too)

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Sunbelt performance here in GA. Has one, I drive by their shop almost everyday. If I can assist you in anyway, let me know. Are you using a F54? I could maybe source a block here and save you shipping one way.

Arnie

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I have a really nice N42 block (All bolt holes are great and the bores are at 87mm, "best" choice for a big overbore) that could be used for just such an occasion that I'd let go for cheap. (read $120 delivered to Sunbelt...) I'm like 35 minutes from Sunbelt but have never been there.

If you are interested let me know...

OTM

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Ask if they have an RB torque plate if they do have them use this as they share the same bore spacing and head bolt locations as the L6 series.

Thanks for that info. I'll probe a little more to see if anyone has an RB plate.

 

And thanks for the offer Arnie and OTM. I'm up to my armpits in blocks (I've got two N42 blocks, two F54 blocks and a complete turbo engine).

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I have to agree with TonyD... you do not truly need a torque plate for overboring an L series engine. The two things that are most important in doing an overbore is the thickness of the cylinder walls and the distance from the cylinder to the head bolt. On an L series engine you have both good thickness and a lot of distance to the head bolts. Now if a shop has one and the price is the same go for it.

 

IMHO the benifets you would get from using a torque plate on a street driven/weekend warrior L series could be negated by filling up with gas from station "A" verses station "B". The whole torque plate deal is just like the E-31 head deal... because a racer who is bound by very strict rules found something that would give him a 1/100 sec advantage under ideal condtions over the next guy people suddenly think that is going to make a difference on their car, well its not, untold hours of seat time will make a difference.

 

Dragonfly

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I have a really nice N42 block (All bolt holes are great and the bores are at 87mm, "best" choice for a big overbore) that could be used for just such an occasion that I'd let go for cheap. (read $120 delivered to Sunbelt...) I'm like 35 minutes from Sunbelt but have never been there.

If you are interested let me know...

OTM

 

 

BEST????

 

 

Please explain reasoning.

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BEST????

 

 

Please explain reasoning.

 

well between the two choices of an F54 or N42...

I'd rather have the extra cylinder wall of the N42 with a monster overbore. Stock for stock the F54 wins because of it's supposed cooling ability.

 

If you want to go really big and wet sleeve the block it doesn't really matter what block you use. A P30 block would even work for that.

 

But in the case of a hot street/race N/A L28 running an 89mm bore and high compression I'd rather have the cylinder wall thickness and deal with the heating issues by other means.

 

That is just my thinking. I'd like to hear what you have to say on the subject.

Personally I'd take my LD28 block, install wet sleeves with flats cut on the sides and sport a 92mm bore... That is just me though. An un-welded 3.3 L6...

 

Dan

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1 fast z, on another forum you recommended the N42 block for a stroker build:

I would HIGHLY sugguest using a N42 BLOCK, as you can almost bore those straight through without any sonic testing. The turbo blocks are NOT siamessed and if you just punch out a 89mm bore straight through, with no offset, then your chances of cynlinder wall blow out is pretty high. The last two blocks that I sonic tested that were F54, couldnt be punched out more than a 1/16. That was if I wanted to obtain a 3 mil thickness, and that was with offset boring.

 

There's one reason for choosing the N42 over the F54.

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When I was living in Birmingham I had my N42 bored out to 89mm by HESCO. They did not have a torque plate but Chuck was a very skilled and detail specific person. More so than other engine builders I had meet. Felt comfortable in his abilities and it worked out great. If sunbelt wasn't as busy as they were at the time I would have paid them to build my motor. Luckily I saved that money for more mods..

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I thought that the F54 was superior?

It is... when you compare it with a stock bore to an N42 with a stock bore.

The cylinder walls aren't as thick on the F54 block which makes them more prone to flexing out and allowing piston blow-by when using high compression or boost with a large overbore.

 

OTM

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