Great info!NickTaliaferro said:We have made a couple odd engines. Using combinations of factory sizes you can get a range of displacement. Each having various benefits.
90x93 = 2.445 (Eds Viggen 2.3 crank c900 2.1 bore)
90x90 = 2.290 (Stock 2.3)
90x78 = 1.984 (Stock 2.0)
93x78 = 2.119 (2.0 Crank with large bore)
The larger bore helps un-shroud the valves. For a normal car there is not much benefit to changing..
Another variable to consider is rod length. The B204, B234 and B235 share the 153mm rod length but the B205 has a longer rod of 159mm. Using these long rods in the 93x78 will give best benefits and I will use this in my next engine.
Are you sure that's wise- abandoning a generally-regarded as "ideal" 1.7:1 rod ratio (153/90) in favor of a longer, potentially weaker, rod, as well as a MUCH thinner, and definitely weaker/less-reliable, piston ... merely for a very slight increase in efficiency brought about by a 1.77:1 rod ratio gotten with a 159mm rod on a 90mm crank?NickTaliaferro said:The B204, B234 and B235 share the 153mm rod length but the B205 has a longer rod of 159mm. Using these long rods in the 93x78 will give best benefits and I will use this in my next engine.
Have you forgotten than I know the (or at least one of the) chief engineer(s) at JE for custom piston design? (also named Nick, oddly enough :cheesy: ) I might not be sharing all my resources either, but really I was just concerned with the idea of fitting 159mm rods to a 90mm crank.NickTaliaferro said:Adrian.. A this is a discussion about modern saab engines.. In the families used in the NG900/9-3 B Pretty sure I can make a B205 based 2.1 Are you forgetting the fact we are a JE pistons dealer and I might not be sharing all the resources I have. Or all the details.
Actually, I got it from someone else, who apparently got it from Nordic.Nick said:I have seen that picture you got from Nordic years ago.. Even compared the parts in the workshop.
The 159mm rods "fitting" the 90mm crank? Not without a seriously thick head-gasket or seriously thin ring-lands, neither of which are ideas I'm too keen on. Unless the Saab literature is WAY off.Nick said:Are you sure about the later rods not fitting.. You have experience with this?
Where on Earth did I say you were using STOCK pistons? Even my reference to "stock rods" in regards to the trapezoidal small end was directed more at other members who MIGHT be considering the idea, as your post didn't make any mention of custom rods when referencing length, and a previous post made a mention of "factory sizes" that I thought people might misinterpret. That's all.Nick said:As I stated the Rod, piston, ring, pin combination is a PACKAGE.. you obviously can't just go swapping parts. I am sure not going to run a stock rod in an engine of this type. Probably not going to be able to find 93mm B205 pistons either. Orignal headgasket sure wont work either..
But the 9000 Aero pistons are ginormously tall, as can be seen, and forged pistons of the same pin-to-deck height might be a bit of over-kill. Forged pistons with the same heigh as the Viggen pistons could easily be made to handle 600+ horsepower.Troll_speed said:You really, really don't want stock Viggen pistons.
Maybe a 2.3 Turbo motor from a 9000 (94+up) is what you're looking for.
I know a few B204L's with 500+ hp and 600+Nm and reved to 7500rpms on regular basis, thus the "hepolite" pistons which are supposed to be weaker than the other std T5 pistons. All these parts will support big bhp as long as the mapping is in order, but eventually the limit will be found.Adrian W said:the stock B204L/B234i rods can handle around 400 horses or so, maybe more, and 7,000 RPM. Doubling the strength should cover almost any practical power goal.