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My new pistons and rods are ready :-)

Arias pistons 94mm lower comp height, Pauter rods slightly longer.





Still with Robie on Isuzone, but soon they'll be on their way to me.

Tommy

Fuckin nice workmanship on the pistons thats for sure!

94mm = 4ZE1 right?

Nick-

Yes 4ZE1 going in a JR.

Rods are 154.5mm, 4.5mm longer than stock with a 22mm wristpin, stock is 23mm. Pistons are for 94mm bore
(4ZE1 block probably can take close to 95mm bore) 92.7mm is stock, comp. height is 32mm (stock is 36.5mm) with a 8mm dish.

I could have gone with longer rods shorter comp height, but would have needed oil ring support.

The pistons are to match this massaged head.




Tommy

very nice!

would have needed oil ring support.

how is that achieved?

Haven't actually seen any myself, but from the names: Plug and Bridge, it is fairly easy to imagine what they do.
It's not expencive either, 20USD extra for the bridge pr 4 piston set, 70USD for the plug pr set.
Acording to the shop doing the engine work for me it's not uncommon either.
But it is one more thing to fail, and 1.63 is a good enough rod/stroke ratio for a supercharged engine.

I did go with the tool steel wrist pin, and the set should be safe to 800+ crank HP.


Tommy

Hang on. Did i hear right? Supercharged? WHY?

Nick-

GeminiCoupe wrote:Hang on. Did i hear right? Supercharged? WHY?

Nick-

Do you need a reason????


lol.

Actual I used supercharged here to indicate any engine beeing force feed (turbo, blower or nitrous)

But yes, the neverending project has seen even more feature creep, and I've desided to go with an Autorotor screwcompressor (OA424 or OA426)

Total price is about the same as turbo charger + nitrous, and it should be more suited to the short twisted traks we mostly have here.


Tommy

any particular reason you went with Arias vs Wiseco, Ross, JE, etc?
what CR are you expecting?

plans for the crank & block?


good stuff!

Only reason is that Robie on Isuzone is a dealer for Atomic speedware, and I wanted to order through him.

CR is exspected to be 9.0ish the final matching of the chambers in the head haven't been done yet, also due to the large squis area the HG thikness will be part of the tuning, and could affect CR as much as .2

Block wil be mostly stock bored to 94mm and mains line honed.

I'm thinking about getting the crank knifed, at least the whole rotating assembly will be balanced together.


Tommy

getting the crank knifed

recently i've been looking into specifics on this, found a few different examples.

knifed:


"bullnosed":

seems like much more material is kept and just the edges are rounded a bit.

found this interesting technique from a DSM builder, refered to as a "butcher" crank:


"we knife-edge the trailing edge and round the leading edge. Much like the shape of an aircraft's airfoil. The result is a smoother "cutting" crank through the oil without the turbulence and parasitic drag that "normal" knife-edged cranks can and will give you. "

opinions, knowledge or experience with any of these specifics?

what boost levels are you planning? any thoughts of o-ringing the block and copper HG?

sorry for the interrogation, trying to learn as much as possible before I attempt my first build.

What I discused with the shop was a lighter version off the last one with sharp edges on either side off the counterwheight,
without removing so mutch of the original shape of the CW's,
removal of material from the rodside mutch like the first pic,
and cleaning upp the outer edge of the CW's to alow for better use of an oil scraper.

Dont have experience with lightening cranks my self, but shop advices to ratain most off the wheight for longivity reasons,
and go more for the aerodynamic improvements, and improved oil controll.

Basickly the plan is to get the max from the Autorotor SC without exceding max boost (1.8Bar aprox).
With a hot cam this is hoped to place it just at the edge off max rpm's for the SC.

Block will be o-ringed, and I will be using copper HG, multi level steel would be better,
and might be ordered when optimum squish distanse is determined.

Tommy

Tommy wrote:Dont have experience with lightening cranks my self, but shop advices to ratain most off the wheight for longivity reasons,
and go more for the aerodynamic improvements, and improved oil controll.

Seeing as the Piazza motor is over square by a fair way, the rotational mass would help in the torque department as well. Id smooth it and keep it, ditto for the steel flywheel. Atleast that way it will want to do a little bit "off boost".

Bob.

keep it, ditto for the steel flywheel.

isn't the stock flywheel absurdly heavy? I recall someone posting on Isuzone a ways back that it was in the neighborhood of 20 lbs!

I just took delivery of a box from Fidanza - 8.5 lbs of aluminum.

I dont think its that heavy.

Id prefer the heavier flywheel, you cant scream on boost all the time. Well not on the road.

One experiment you can do is with wheels. If you can get some realy heavy steel rims and fit them to your car/truck, you will notice the increase in torque feel that you dot get with light alloy mags.


Bob.