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Discussion Starter #1
I'm considering blueprinting my '93 B234. A pressure test has shown that the compression diference of 25psi is down to a leaky piston ring/worn bore on cylinder #2. So, it's a lump out job to rectify that. Given it's out, I'm contemplating having it blueprinted for maximum balance and smooth perfromance.

On the "definite" list is:
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[*]Lightening/shot peening the rods
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[*]removing the balancer shafts and chains
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What other options would folk consider, and what are the benefits?

Cheers

Mark
 

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Removing the balancer shafts will make the engine less smooth, more raw but it should rev more readily, according to experiences documented by Kevin Yankton anyway. Certainly, my car is much smoother with nice new chains. But that said, I'm not planning to attempt to get > 300bhp out of the lump in mine, so I've gone for safety and stability over sheer performance.

Lightening the rods sounds like a good idea, nice to do if you can afford it.
 

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* Lighten the flywheel

* Shot peen crankshaft

* Of course, balance complete rotating assembly.

When digging this deep into your engine, you might consider going all the way and install billet rods (the originals are pleny strong, but also quite heavy), crankshaft and forged pistons...

BTW - oil cooling jets for the piston decks were only incorporated in B235R and 205 hp spec B205R engines, right? In that case...
 

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BTW - oil cooling jets for the piston decks were only incorporated in B235R and 205 hp spec B205R engines, right? In that case...  [/b]
I'm sure I read that some of the older (much older) turbo models had this as well.

Andrew
 

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Are you into real blueprinting to get the max power while still having the car "in spec"? Or are you going beyond that to get max power at any (reasonable) risk?

You can grind the big ends to max off-centre to increase the stroke. This will mean going to the minimum journal diameter, so no more re-grinds possible. Obviously this is self limiting as you weaken the journal as you increase the stroke.

Take the bores out to max. Again a balance of extra cc's against risk of cracked block.

Lighten the pistons. More risk.

Remove a piston ring or two to reduce friction. Probably not for you unless you rebuild engine between trackdays.

There are some production engines where the block was stiffened by welding / bolting cross-bracing to the outside of the block.

X-Ray every thing for cracks - especially the con rods. Cheapest way to do this (I'm told ) is to date a hospital radiographer


Good luck!!
 

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you don't need to lighten the rods, just get them checked for cracks and then polish and shot peen.
You will benefit from knife edging the crank and then getting it polished. You then take it out to max bore and fit cosworth forged pistons, these are considerably lighter than stock and much stronger. This is where you will make best gains and it gives the con rods an easier life also...less weight to keep hold of at max revs!
The flywheel can be lightened extensively also.
Get the head gas flowed by a company who do it as a living...they have the expertise. Then get the whole lot balanced together.
 

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Discussion Starter #10
I'm not aiming to go too OTT on this.. I just figured that whilst I had the lump out (or alternatively find a decent s/h one to work on) I may as well get a few reasonable mods done that would give me a performance benefit.

It's useful to know all the options and consider the performance vs cost benefit.

I know that taking the balance shafts out will make things rougher but by having it balanced, I hoped to counteract some of that.

Ref cams, I understand the trick is to get hold of a very early set of 9000 cams, which were ground much more aggressively. My local indy reckons that it was found that too many folk were planting their 9000s in hedges etc not being used to such power and acceleration in a family saloon when they first came out so Saab turned the wick down a bit.

I'm certainly considering mild overboring, not so much to increase capacity but to lower the compression ratio which will be better suited to higher boost levels.

Once I've got my potential shopping list together, I'll make enquiries of various specialists.

I already have the head ported & flowed with big exhaust valves.

Don't forget that in doing this I'm going to have to consider the gearbox budget as well
...
 

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If it's a B234R it already has good (albeit not too terribly lightweight) forged pistons. They're easily useable past 25 psi of boost as Mr Yankton has shown. Shotpeening the rods is always good, as is checking for crack's in it, the crankshaft, and the head if it's coming off as well. A lot of people have been putting anti-friction coatings on the pistons skirts, and ceramic coatings on the piston tops, combustion chambers, and exhaust valves. You might consider looking into those. (http://www.performancecoatings.com/) I hear fully coated engines run much much cooler and with lower emmissions. (The ceramic coatings reduce the pocket cooling of small amounts of gasses in the cyllinder. This gives it a better burn.) Some of the anti-friction coatings can go other places as well: Crankshaft journals, piston pins, cyllinder walls, camshaft lobes, lifter bores, insides of headers to smooth gas flow. Also consider Total Seal gapless rings. They aren't very good for high revving, and you won't see much advantage out of the box with them over the stock rings. But after 80K miles or so, they typically show very little leakdown comparitively. Not sure how good they are with high boost. Just worth looking into ...

ciao
 

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Originally posted by Mark E:
[qb]I'm certainly considering mild overboring, not so much to increase capacity but to lower the compression ratio which will be better suited to higher boost levels.
[/qb][/b]
I'm really confused now. Surely increasing the bore increases the swept volume, whilst the volume with the piston at TDC stays the same. Therefore the volumetric compression ratio will increase. Or have I lost the plot completely?
 

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lol Mark B you're right. The combustion chamber in the B234 I believe is mostly in the head. It's size won't change when you overbore the motor, but the swept volume will, so the compression ratio will go up. But hey, a nice set of low compression Cosworth forged pistons would fix that.
 

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But hey, a nice set of low compression Cosworth forged pistons would fix that.  [/b]
Thats what I did...expensive though!!


I was going to get the pistons coated with an anti detonation coating but whilst it was only £25 per piston I was told the cosworth pistons were more than adequate for my application of running up to 2 bar boost spike with 1.6 bar steady boost pressure assuming fueling was correct. Thinking back now maybe I should have had it done, extra protection in case of lean mixture times!

http://www.ctgltd.co.uk/technology.php?id=...Crown+Treatment
 

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Saabine's Cossie pistons weren't exactly cheap at about 900 euro/set - but set against the total cost of a major rebuild such as this, you might consider it unwise to skimp here.

That is, unless the B234R pistons are forged - that's something I heard here for the first time...
 

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If you read in some of the other threads they talk about how the B234R pistons are STRONGER than the B235R, and the B235R I know is forged ... also I believe it was mentioned then as well that the B234R's were forged. Even from deduction though, it's clear they must be. Along with the crankshaft and rods. Hell even the old C900 16V engines had forged cranks and rods. Tough stuff ...
 
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