Prius Pistons

[JustDidIt]

Originally Posted by tooter

That would seem to indicate that trying to run Atkinson pistons in an Otto engine did not go well.

Ahhh.. Come'on Tooter...you of all people... lol - I'd like to see more optimism. The better answer would be, most people are too skurd to try it - Those who have...don't post here on YW...or just have better things to do than post cool EUREKA DIYs ... Like your manifold. :)

I've found a FULL 2012 Yaris 1NZ-FE cylinder head super cheap. Now just waiting to hear back if I can have it shipped or if I have to go pick it up.

[xnamerxx]

I wouldn't take the crank having a different part number as meaning anything more then it might not have a standard bolt pattern or it might require a longer snout.

Here is a cutout of a 1nz-fxe from an autoshow.

You can see the giant mechanical flywheel, which doesn't have provisions for a starter and you can see the giant start/stop starter on the front of the engine.

I seriously doubt that the FXE piston would have any issues in the FE engine aside from the massive increase in compression that would cause some tuning issues. The compression being close to 13:1 doesn't really scare me as long as you can control the tune, which is pretty much only possible with a aftermarket ECU. I've seen 4.6l engines running 12.6:1 on 91 octane its doable just takes more work.

The piston being HYPEREUTECTIC doesn't mean it can't handle power it just means the piston is less elastic than a forged piston, meaning when its given a shock like say detonation it doesn't deform as much so if the material sees a strong shock it will crack rather than deform. Hypereutectic pistons have some great properties about them that make them suitable choices for performance oriented situation like the fact they have little heat deformations which means they don't compress and swell as much with heat which means you can run a piston tighter in the bore and you can also run a lighter piston which makes the engine more efficient.

[Viperoni]

Here's another thought; since 13:1 *may* be on the high side... are there thicker head gaskets we can use?

[tooter]

Originally Posted by JustDidIt

Ahhh.. Come'on Tooter...you of all people... lol - I'd like to see more optimism.

Sorry, I really didn't mean to come off as being negative. I was only commenting on the lack of feedback as to what happened after 13:1 pistons were installed. There's no information. I'm all for trying new things. Wait till you see what I'm cooking up...

The better answer would be, most people are too skurd to try it - Those who have...don't post here on YW...or just have better things to do than post cool EUREKA DIYs ... Like your manifold. :)

That manifold wasn't even my idea. I can't take credit for it. The guys in Puerto Rico did it first. I just thought it looked really cool and wanted one on my engine.

I've found a FULL 2012 Yaris 1NZ-FE cylinder head super cheap. Now just waiting to hear back if I can have it shipped or if I have to go pick it up.

Sounds good!

The Atkinson engine is really strange. Did anyone notice that it fires on every revolution?

[JustDidIt]

Originally Posted by xnamerxx

Here is a cutout of a 1nz-fxe from an autoshow.

Sooo Pretty!

Originally Posted by xnamerxx

I seriously doubt that the FXE piston would have any issues in the FE engine aside from the massive increase in compression that would cause some tuning issues. The compression being close to 13:1 doesn't really scare me as long as you can control the tune, which is pretty much only possible with a aftermarket ECU. I've seen 4.6l engines running 12.6:1 on 91 octane its doable just takes more work.

Originally Posted by Viperoni

The (static) CR would be 13:1 if you use Prius (FXE) pistons.
The dynamic CR is apparently 11:1 if you use FXE pistons

To answer your question, it depends. A quick googling seems to say that there's diminishing returns, especially since you're not improving the breathing of the motor and filling the combustion chamber with more air/fuel.
One calculator said 6.5% and that's more or less what I read on another site as well... which I think is a bit low, but could be bang on. In any case, a 6.5% increase is 7hp.

Originally Posted by Viperoni

Here's another thought; since 13:1 *may* be on the high side... are there thicker head gaskets we can use?

If your original post is correct, then most I may need to change when running 11:1 compression is 91 instead of 87 pump gas, besides some EM. But even then....I run on 87 now...at the supposed static CR of 13:1 or dynamic 11:1.

Originally Posted by tooter

Sorry, I really didn't mean to come off as being negative. I was only commenting on the lack of feedback as to what happened after 13:1 pistons were installed. There's no information. I'm all for trying new things. Wait till you see what I'm cooking up...

That manifold wasn't even my idea. I can't take credit for it. The guys in Puerto Rico did it first. I just thought it looked really cool and wanted one on my engine.

If if you weren't the original.. "Imitation Is The Best Form Of Flattery"... Your idea to hack up a manifold and try something new got me thinking. The way my MG1/MG2 sits, I could never use the 1NZ-FE intake or even your 'Tooter manifold' - the throttle body would conflict with my inverter. But I was thinking of doing something with the 2AZFE intake manifold because the throttle body would come out the passenger side...problem is - the manifold is plastic.



Not sure how I could 'weld' the 1NZ flange onto the 2AZFE plastic tubing :( I may just have to make/design my own. Luckily you already have the flange I need to weld onto!

[JustDidIt]

Originally Posted by JustDidIt

I've found a FULL 2012 Yaris 1NZ-FE cylinder head super cheap. Now just waiting to hear back if I can have it shipped or if I have to go pick it up.

For a decent EMS...Still haven't found much info on whether or not I can get by with the AEM F/IC or if I'll have to step all the way into the AEM EMS2 $$$$ :( Tuning is my biggest concern at this point. Just not looking to drop $2k just yet on EMS.

[xnamerxx]

Here is a comment from someone I know who used to tune cars for AEM, about using it for tuning my car.

the FIC was good, but i only used it on FI apps. in FI apps we only retard the timing, in your case i would imagine you want to increase the timing, which it cant do, can't predict the future, only delay it

[tooter]

Originally Posted by JustDidIt

If if you weren't the original.. "Imitation Is The Best Form Of Flattery"... Your idea to hack up a manifold and try something new got me thinking. The way my MG1/MG2 sits, I could never use the 1NZ-FE intake or even your 'Tooter manifold' - the throttle body would conflict with my inverter. But I was thinking of doing something with the 2AZFE intake manifold because the throttle body would come out the passenger side...problem is - the manifold is plastic.

Is this the layout of your engine? And if it is, is your intake at the front of the engine or behind it?

Not sure how I could 'weld' the 1NZ flange onto the 2AZFE plastic tubing :(

I'm not sure, but I think that the plastic might have been ultrasonically welded. And that "snail" style manifold might still have clearance issues, but that could be easily determined simply by taking some measurements.

I may just have to make/design my own. Luckily you already have the flange I need to weld onto!

No rpoblem.
I'll always be stocking them. Since the design is finalized they can be manufactured as needed.

[BEEF]

I am not sure if garm commented earlier in this thread but you can get pistons from him in a variety of thicknesses (compression ratios) so the big reason to use the prius pistons would be to save money.

I can't remember exactly what he said he had but it seems like he had 9:1, 11:1 and a 12:1. I may be a bit off on that one but you could ask him directly.

[JustDidIt]

Originally Posted by BEEF

I am not sure if garm commented earlier in this thread but you can get pistons from him in a variety of thicknesses (compression ratios) so the big reason to use the prius pistons would be to save money.

I can't remember exactly what he said he had but it seems like he had 9:1, 11:1 and a 12:1. I may be a bit off on that one but you could ask him directly.

Saving $$$ is the idea... otherwise your correct you can get Arias Pistons with the CR ratios of 9:1 - 14:1 for the 1NZ...

Basically I just need the Cams and Cam gear with EMS...and I can test out this "prius Pistons" theory - not only will I get a bump from swapping cams from 1NZ-FXE to 1NZ-FE (stock 78hp to 108hp) ..but I should get a small boost from the 10:5 to 11:1 CR increase. I am sourcing a full 1NZ head now.

[cali yaris]

^ Or CP pistons, or a couple of other brands. All available in whatever size/compression ratio you want. I wouldn't pay the premium just for the Arias name, but that's up to each customer; they do make great products.

[JustDidIt]

Originally Posted by tooter

Is this the layout of your engine? And if it is, is your intake at the front of the engine or behind it?

My intake manifold is up front like the 1NZ-FE but the manifold is mounted/designed with the throttle body sitting directly on top in the middle of the manifold.



Picture of my front strut bar install... shows the layout better.





I really think I have the clearance to make the 2AZFE intake manifold work or something similar because I don't have much in the way if the intake was routed to the passenger side of the engine as the 2AZFE would if mounted on my 1NZ.



If the 2AZFE manifold doesn't work, My idea is to create the log style intake with fairly long intake runners. Basically the 1NZ-FE reversed. Such as examples below:

[cali yaris]

I don't see any baffling in the large picture that xnamerx posted. The inside of the cutout intake manifold is shown in blue, right? Looks pretty smooth and open.

What's the purpose of a different manifold?

off-topic. How difficult would it be to transplant my motor/trans into a Prius?

[JustDidIt]

Originally Posted by cali yaris

I don't see any baffling in the large picture that xnamerx posted. The inside of the cutout intake manifold is shown in blue, right? Looks pretty smooth and open.

What's the purpose of a different manifold?

off-topic. How difficult would it be to transplant my motor/trans into a Prius?

Haven't ever really looked inside mine but I doubt its as smooth. I'm sure this one was polished up and powder-coated for display.

The 1NZ-FXE manifold was tuned for for a specific RPM range with most efficient MPG... I'm not concerned about MPG but more looking to increase HP. Most N/A motors w/o going ITBs have longer intake runners - not like the Prius's 1NZ-FXE manifold.

Are you speaking of your 1NZ-FE? The Motor transplant shouldn't be difficult and was done by the Bonneville Landspeed Prius. They swapped the Otto Cycle 1NZ-FE from an Toyota Echo in but didn't do the Prius pistons swap. I'm looking to do both. Besides the MG1/MG2 and tranny the engine itself (mounting points) are exactly the same as the 1NZ-FXE

Transmission transplant - hmm...depends on if you want to keep the hybrid system or not.

[JustDidIt]

Originally Posted by xnamerxx

Here is a comment from someone I know who used to tune cars for AEM, about using it for tuning my car.

The FIC was good, but i only used it on FI apps. in FI apps we only retard the timing, in your case i would imagine you want to increase the timing, which it cant do, can't predict the future, only delay it.

I would probably just need to adjust the timing and A/F ratio - if you moved the timing chain up a bit manually with a AEM F/IC you could retard the timing to adjust according while adjusting the A/F ratio to compensate for the OEM tune (as you mentioned..can't increase timing with the AEM F/IC only retard)

[xnamerxx]

Originally Posted by cali yaris

I don't see any baffling in the large picture that xnamerx posted. The inside of the cutout intake manifold is shown in blue, right? Looks pretty smooth and open.

What's the purpose of a different manifold?

off-topic. How difficult would it be to transplant my motor/trans into a Prius?

Atkinson cycle engines don't have large powerbands but rather a small efficiency zone, so whereas a traditional otto engine is probably about 27-33% efficient between 2-5.5k a Atkinson engine is 35-39% efficient between 4-4.5 rpms. So because it uses a hybrid drive transmission the engine never really cycles through its rpm range but rather like a CVT just has a gearing change that keeps the engine happy but still allows acceleration while the electric engine is providing the majority of the mechanical drive.

I don't think the transmission bolts up to the 1nz-fxe, it would be far simpler to get an electric engine/generator and attach it to the crank snout like a supercharger to get some extra assist that way. That kinda the way honda currently does it with the CRZ/Insite

[JustDidIt]

Originally Posted by xnamerxx

Atkinson cycle engines don't have large powerbands but rather a small efficiency zone, so whereas a traditional otto engine is probably about 27-33% efficient between 2-5.5k a Atkinson engine is 35-39% efficient between 4-4.5 rpms. So because it uses a hybrid drive transmission the engine never really cycles through its rpm range but rather like a CVT just has a gearing change that keeps the engine happy but still allows acceleration while the electric engine is providing the majority of the mechanical drive

I don't 'feel' my Prius engine at all under 3000k but the usable rpm looks to be about 3000-5500. Swapping the cams yet keeping my pistons will essentially switch me over to otto cycle with a touch of compression increase.

[xnamerxx]

I can almost guarantee you, you'd be doing more harm then good by swapping to otto cycle cams in your engine. The prius is mainly powered by the electric engine, so to make that as efficient as possible the torque output on the gas engine needs remain a constant. The numbers I listed were WAG and so probably not accurate. Remember your gas engine isn't directly connected to the wheels, so its RPM's are also not a contant

Here is a website that explains how the HSD powersplit device works. Website

Upping the power on the gas engine doesn't help as much as you'd think since only torque at certain rpms provides assist. Since the engine only revs to 5k you'll be throwing away all the constant torque of the fxe to gain the peak torque of the fe all with major loss and no benefits. You have to think of the gas engine as a electricity generator/backup power unit rather than a PU. You can rev the nuts off the Prius engine and the car won't move unless the electric motor is moving.