Can the deck height of an iron block be increased? 2

[1450racing]

I am new to this forum, and my searches did not turn up the subject matter at hand. I have an inline 4-cyl engine w/ cast iron block, with a rather short deck height. I am trying to increase the rod ratio to something reasonable, however this engine will also be turbocharged. I believe the only solution to get a reasonable ring stack arrangement, and a suitably long connecting rod will be to raise the deck height by approximately .750".
Is it then feasible to have an iron spacer furnace brazed to my current block, then to insert taller sleeves? If so, what companies do such work? Besides block distortion, what other shortcomings am I not aware of? I seem to recall Chrysler doing a lot of furnace brazing to their 2.2's during the mid '80's for their racing programs.
I apologize for so many questions, but much of my planning rides on this one issue.

Bob

 

[GregLocock]

Rather than brazing it why not use a second head gasket, and some form of wet liner arrangement?



Cheers

Greg Locock

 

[patprimmer]

Why not use an iron spacer that is 0.75" thick, and dry or wet sleeves that come to the top of the spacer.

Use no gasket under the spacer. Something like Loctite 515 will seal the water and oil passages.

Use 0.750" longer bolts.

Use a standard gasket between the head and the spacer.

This will reduce the strength of the block as the sleeves will not be as strong as the iron that was removed from the bores regards the forces trying to separate the main webs from the deck.

The sleeves should be from centrifugal cast iron, which is generally a better material than the original bores

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[SMOKEY44211]

One other avenue you might explore is using a single compression ring. Total Seal makes a gapless ring that will live. There's 10-15 hp. gain over traditional ring packages on a 350 size V8. I know its not the .750" you're looking for but it makes for a nice light piston. You should be able to pick up .250"-.500" in rod legnth with this method. -------Phil

 

[1450racing]

Thanks to all for your suggestions. I fear I am still leaning towards a more 'permanent' solution. Thoughts of leaking gaskets, leaking spacers, shifted cylinder liners, etc have me concerned, especially when dealing with the stresses of forced induction. Currently, I have a 1.49:1 rod ratio to work with, I was hoping to approach 1.75 or so.

I have another N/A project engine I'd like to use longer rods in, I can get near 2.3:1 due to the shorter stroke in that engine, if I can raise the deck height a similar amount. Please, keep the suggestions coming...

Bob

 

[crashbox455]

http://www.theoldone.com

Larry Widmer does this to honda motors, it's in the archives somewhere....

 

[enginebob]

I know of diesel engines that use steel and aluminum spacer plates under cylinder heads, have never seen a leaking problem because of it.

 

[patprimmer]

If it is done right it wont leak.

I would use a gasket as a template to make the plate, but I would increase the bore to clear the compression sealing area of the gasket. I would make the plate slightly thicker than needed.

I would make the sleeves with a step, so they fitted down until the step hit the top of the original deck, and the sleeve protruded above the spacer a little.

The stepped portion of the sleeve would be big enough in OD so that the compression seal on the gasket sealed against the top of the bore, not the against the spacer plate.

I would drill and counter bore some extra holes in the spacer plate at a convenient location to add extra bolts to hold the plate firmly in place when the head was off the engine.

I would bolt the plate on with the Loctite 515 sealant between it and the original block deck surface, let it set, then skim the deck to the exact desired height.

I would then press in the sleeves until they sat firm against the deck of the original block

I would then skim the deck again until the sleeves were flush with the deck of the spacer plate.

Wella, one tall deck block with better cylinder wall material, but slightly reduced integrity between the deck of the original block and the crankcase.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Tmoose]

Are you going to be able to find a longer chain or belt to drive the cam (OHC) or get longer pushrods (OHV)?

 

[1450racing]

The timing chain is not an issue, I make those from bulk material anyway. The chain tensioner is not an issue either, it is adjustable and can be modified further if needed. ARP has been able to produce custom fasteners as well in the past. The timing cover must be welded to compensate for the added deck height, but as it is aluminum it is easily modified. I am tending to veer towards the concept of sealing and bolting the spacer to the block per Pat's recommendation, certainly there are enough areas to drill and tap into for the purpose of attaching the sealer to the deck surface.

Again, thanks to all who've replied.
Bob

 

[harrisj]

What about cooling?

This is the hottest part of the cylinder, and it's normally surrounded by water jacket. Now you will have solid metal around it with an indifferent heat path. Detonation?

John

 

[patprimmer]

Water will be passing through all the normal water passages.

If it is a drag race motor, or runs on methanol, cooling should not be a problem.

As I have mainly worked on methanol fuelled drag motors recently, cooling slipped my mind.

The top of the bore will not have good heat transfer without.

Some heat transfer medium between the spaces and the sleeve could help.

If heat concentration at the top of the bore is an issue, the sleeves could be fitted with "O"rings, and an annular grove cut into the plate.

Some thought would be required re water circulation and the points of getting it into and out of the annular groves.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[1450racing]

The application for the turbocharged engine is that of a road car, therefore cooling is essential. I had assumed, perhaps incorrectly, that when the spacer is made the coolant passages would be mimicked in the spacer material.
The second application was for a land speed record engine, so between the desert environment and the need to be able to hold full throttle for 3-5 miles, I'd say cooling is even more important!

Bob

 

[patprimmer]

Bob

If the water goes through the plate in the fashion it goes through the deck of the original block, The top of the cylinder will get hot because there will be poor heat transfer between the cooled plate and the heated cylinder sleeve.

You need to get some cooling to the top 3/4" of the bore.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[proengines]

The older cat diesel engines used a flanged liner that sat on the deck surface and a steel spacer plate without any problems at all, apart from the liners eventually fretting into the top of the block.
Cooling wise it would not be a lot different to an aftermarket cast iron V8 engine block, some of these have 5/8" or so deck thickness.
You still have coolant passing up to the cylinder head through the coolant passages, so there is some cooling there.
What type of engine are you working with?