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Old 08-22-2007, 04:34 PM   #1
Optical NZ
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Default EJ25 open deck block build

Does anyone have any advice on things you can do to strengthen an open deck block for a reasonably high HP build? 400 -450hp

Ive built a few 2L engines up before, but not a 2.5. The only block available in my area is an open deck. Are there things you can do to strengthen the bores? Or will they we ok for that power level?

im not going to go to the effort of sleeving. Will maybe look into doweling the water jacket if it has been proven to be effective?

Thanks
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Old 08-22-2007, 08:29 PM   #2
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forged rods and pistons and a semi or fully closed deck
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Old 08-22-2007, 08:51 PM   #3
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I know of guys running open deck EJ25's to the tune of 400+whp and haven't had issues
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Old 08-22-2007, 08:58 PM   #4
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use arp head studs..ej25d's have headgasket problems in NA form..boost will add to the problem even more.
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Old 08-22-2007, 10:25 PM   #5
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very true with the hg deal. just be care ful with the boost
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Old 08-23-2007, 12:37 AM   #6
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Pinned cylinder walls.

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Old 08-23-2007, 12:48 AM   #7
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wow pretty nice
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Old 08-23-2007, 12:49 AM   #8
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why not just start with a semi closed block??? less hassle they are all over the place
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Old 08-25-2007, 06:23 AM   #9
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well the problem is there are no semi closed blocks that i can get my hands on in New Zealand..

im interested in these strengthening tricks

do you have any more pics Reddevil? are they pinned at top and bottom?

ive thought about tig'ing some metal to brace the cylinder walls, but im unsure how sucessful this would be.. might warp the block and ruin it?
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Old 08-25-2007, 10:06 AM   #10
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Just do forged internals..you don't need to make the block stronger unless you're daily driving 50 PSI or so IMO.
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Old 08-25-2007, 07:34 PM   #11
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the car will be tracked at around 20psi, does that change anything?
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Old 08-26-2007, 03:47 AM   #12
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Here is Australia we have the same problem. There is really only the open deck 2.5 available and they are hard to get also.
Here is what we do.
Overlay a head gasket over the deck. This will show you where to fit the dowel pins so they dont impede water flow.
The two large central pins are 19mm diameter and the smaller ones are 10mm diameter. All dowels are 20mm deep. Dowels are made of machining grade aliminium rod. Readily available and cheap.
Mind you after fitting these the bore will be out of round so a size up in piston will be required. Only go one size up so you leave as much metal in the block as possible.
When fitting the dowels do not take too much out of the inner section of the casting, You do not want to make the bore section weak where the pin is.
Typically the dowel pins are fitted with a thou or two interference fit. You could even leave them in the freezer to shrink them a fraction before fitting.
Make the pins about 22mm long so they are machined flat to the deck when the deck is finished off.
I have attached a pic of what it looks like when its done.
We have guys running high tens at the drags on these blocks so it definately stiffens things up.

If you need more info send me a PM.

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Old 08-26-2007, 04:38 AM   #13
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I just used brass rod, used a hand drill and reamer, then used a small lathe to mill the rods to press fit.

I did not machine the bores the first time as it was an experiment, and "out of the box" it was running 12.5 @ 112mph.

I have since actually had the block bored to 100mm pistons.
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Old 08-26-2007, 06:21 AM   #14
Optical NZ
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very interesting thanks for the input.

i'll have a chat to some block machinists and see if they are willing to have a go !


oh, do you just put these dowels in at the top of the block? any point in having the at the bottom too, if not?

Last edited by Optical NZ; 08-26-2007 at 06:26 AM.
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Old 08-26-2007, 12:40 PM   #15
mick_the_ginge
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I've always wanted to try this stuff : http://www.hardblok.com/info.html

You have to use wax/soluable rods to maintain a water pass through while the stuff sets. You then melt the rods out to remove them. Basically you turn an open deck into a closed deck

They say you can use it on aluminium blocks
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Old 08-28-2007, 04:44 AM   #16
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Quote:
Originally Posted by Optical NZ View Post
oh, do you just put these dowels in at the top of the block? any point in having the at the bottom too, if not?
The bottom doesnt need anything as its already supported by the block casting. By having the dowels only 20mm deep it allows for water to pass around the block without restriction.
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