2NZ-FE Supercharged Limits

[iwanttobeamole]

Hi all,
Evidently I'm new here. I'm also a new owner of a (not new) Yaris which has a 2nz-fe and a JIMZE supercharger kit.

I have a question for all the tech heads and boost boffins out there.

Preamble
On the assumption (and I could be wrong) that the 1nz and 2nz engines are identical (components) but for crank, stoke length, and block length, (so same rods and pistons etc) and the undestanding that the accepted safe limit to the 1nz-fe is ~150whp, here is my question.

The Question
Would a 2nz making more boost so as to make say 130whp, be as reliable as a 1nz making less boost, so as to also make 130whp..

Postamble
Now I know there's overhead on the engine load to run a supercharger, and one that's been overdriven will put more load on the engine still, but lets assume I'm aiming for 130whp, so as to stay well within the engine's understood safe limit of 150whp

Notes
A little background in case anyone wonders. Car is a 2000 Vitz/Yaris (we had them both here in New Zealand) 2nz-fe Manual.

[thebarber]

I would imagine the same percentage of power gained would be safe.....so 150whp on a 1nz would be about 135whp on a 2nz?

[iwanttobeamole]

Yes you're dead right.
I've also since had a conversation with a friend which prompted me to think about the crank, and the pressures being exerted on it between the 1nz and 2nz. Of course the 1nz will have more leverage from having a longer throw, so at a equivalent percentage of power between the two engines, as you mentioned, the rods would be under the same amount of pressure.

Awesome.

Now to tuning it. (original piggyback that came with the kit is fubar, so it's new ECU time)

Thanks :P

[why?]

I think that a more important measure would be boost pressure. If both engines have the same parts and the same materials, the compression ration and the boost pressure is what would matter in regards to blowing the engine up. according to wiki both compression ratios are the same.

Now it seems from the projects on here that around 8 or 9 psi is about the highest the stock motor can handle for long period at times.

[thebarber]

^^ what he said...i wouldnt run more than 9psi

[Parmas]

In my opinion a "20cm" (1nzfe) rod is more prone to bend than a "15cm" (2nzfe) rod. Thus a shorter stoke can benefit to withstand a slight more boost than a longer stroke.

So we make it real if the max boost of a 1NZFE is 9psi .. I would say the 2NZFE could be able to reach 11psi as a limit...

This is just a thought of discussion and I cannot prove it myself..

[codemonkey23]

Originally Posted by Parmas

In my opinion a "20cm" (1nzfe) rod is more prone to bend than a "15cm" (2nzfe) rod. Thus a shorter stoke can benefit to withstand a slight more boost than a longer stroke.

So we make it real if the max boost of a 1NZFE is 9psi .. I would say the 2NZFE could be able to reach 11psi as a limit...

This is just a thought of discussion and I cannot prove it myself..

just a question.. 1nzfe's ROD longer than 2nzfe that made it stroker.. or is the crankshaft is bigger allowing the stroke to be longer? thanks

[Deadlock Riff]

Originally Posted by codemonkey23

just a question.. 1nzfe's ROD longer than 2nzfe that made it stroker.. or is the crankshaft is bigger allowing the stroke to be longer? thanks

Crank journal positioning is what determines the stroke. Rod length only changes the height of the piston in the cylinder.

[Rednaz]

Hi,
and hyperthetically speaking, if Mole had custom forged rods made; would he be able to drop the compression still and does any manufacturer make low comp pistons for the 2NZ? Or could you just make the custom forged rods set that would accomodate the 1NZ forged pistons?
I have a 2NZ myself and I'm doing some research on getting forged internals to properly boost it when the time is right. I found a company that can make custom forged rods at a decent price in Cape Town but they don't produce forged pistons.
Thought I'd ask here since Mole might be able to use the info as well. Sorry if I'm going abit off topic.