Adding ITB to 2NZ... Big power gains

[RomanDave]

Hi,

I've tried a few different things on my engine while running a Link G4+ ECU where it's quite easy to quantify if a mod has made more power or not.

Basically with the standard intake, changing any of the airbox piping or air filter or anything like that, including completely removing all of it (MAF not needed anymore) does absolutely nothing at all.

So looking at the tiny throttle body and tiny long runners, thought I'd slap together an ITB setup on an otherwise standard 2NZ motor.

Couldnt believe the difference!

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Now pulls decently to ~7200rpm where it valve bounces.

At the drags ran a 16.4 @ 83mph which was 1.2 seconds faster than with standard motor and intake.

2.5 second 60ft.
I reckon it could get into 15s with a C56 gearbox and a good launch.

Took it to a trackday and despite the C152 gearbox really killing the fun (only 2 usable gears) it was a real blast.

https://www.youtube.com/watch?v=sFatZ3pmr18

[ElMagnifico]

Nice. Are those trumpets 3d printed?

[mitch9521]

Sounds really good!

I wish my NCP131 was cable throttle, I would love a set of ITBs on my 1NZ-FE. I'd need to run a standalone of piggyback ECU to even get the car to run with a cable setup.

[RomanDave]

Nice. Are those trumpets 3d printed?

Yes the trumpets are 3D printed, and the base piece which connets the throttles to the head is 3d printed. Then wrapped in carbon.

It was supposed to just be a quick test piece but it's managed to hold up for a few months so far!

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[Turbiini]

almoust indentical top end power that i have with my 2NZ with itb setup. 100whp but valvefloat at 6800rpm

[RomanDave]

almoust indentical top end power that i have with my 2NZ with itb setup. 100whp but valvefloat at 6800rpm

I found adjusting the ignition timing helped a little bit.

If you dont have enough ignition advance, the gas is still expanding as it goes out the exhaust - so higher pressure on the side of the valves holding them open so reduces effective spring rate.

So advance the timing more and seemed like I could squeak a few more RPM out of it.

But not really the fix needed!

[kevinj93]

All the gain seems to be from about 4500 RPM up. I very rarely see revs that high on my 2NZ-FE in normal road use, but more midrange would be nice. Anyone ever tried the 1NZ-FE inlet manifold and TB on a 2NZ?

[mitch9521]

All the gain seems to be from about 4500 RPM up. I very rarely see revs that high on my 2NZ-FE in normal road use, but more midrange would be nice. Anyone ever tried the 1NZ-FE inlet manifold and TB on a 2NZ?

AFAIK the intake manifold and throttle body are the same between the two. We never got the 2NZ-FE in anything over here in North America so I could be wrong.

[kevinj93]

From memory, there was a dyno run listing from a member who discovered his 1NZ-FE was fitted with a 2NZ-FE inlet manifold. It showed a big difference when he replaced the manifold with the correct one. So there may be a difference. I would have to see the 2 side by side and compare.

Of course, if the 1NZ-FE manifold has larger cross section runners, this could actually detract from the midrange on the 2NZ-FE..

[remcafee]

itbs are awesome! i need some on my 1nzfe, i bet they sound amazing

[RomanDave]

itbs are awesome! i need some on my 1nzfe, i bet they sound amazing

There's a video link at the bottom of the first post, this:

https://www.youtube.com/watch?v=sFatZ3pmr18

[RomanDave]

From memory, there was a dyno run listing from a member who discovered his 1NZ-FE was fitted with a 2NZ-FE inlet manifold. It showed a big difference when he replaced the manifold with the correct one. So there may be a difference. I would have to see the 2 side by side and compare.

Of course, if the 1NZ-FE manifold has larger cross section runners, this could actually detract from the midrange on the 2NZ-FE..


The heads are the same between the two, year for year (same part number)

and thats head, cams, valve springs, valves, etc etc.

No difference there.

The intake manifolds do have either 1NZ or 2NZ moulded into the plastic but they also "seem" identical year for year.

The later model 1NZ motors look to have a different manifold where the throttle body points more upwards. I think these are ones where e-throttle is fitted.

But they've all got super long, super skinny runners.

There's not going to be a massive difference swapping between any of them, I'd imagine.

[RomanDave]

All the gain seems to be from about 4500 RPM up. I very rarely see revs that high on my 2NZ-FE in normal road use, but more midrange would be nice. Anyone ever tried the 1NZ-FE inlet manifold and TB on a 2NZ?

It's a cylinder filling issue.

The reason it doesnt gain any power at lower rpm, is because in factory form the motor can already fill the cylinder with air very near 100% full.

Then you can only make so much torque from that much air/fuel pushing the piston down.

The only real options for low end or mid range power are forced induction or more displacement.

Or otherwise, changing the gearing can make an incredible difference.

Also when the motor doesnt completely fall over on its face when you rev it some more, it definitely changes your driving style a bit.

I've owned this car for 8 years completely 100% stock, since 30,000km old and I've always driven it like a complete nanna. As it doesnt want to rev, so you end up shifting short anyway.

But when that top end power is available, you use it!

More so when C56 is fitted :D

[mitch9521]

It's a cylinder filling issue.

The reason it doesnt gain any power at lower rpm, is because in factory form the motor can already fill the cylinder with air very near 100% full.

Then you can only make so much torque from that much air/fuel pushing the piston down.

The only real options for low end or mid range power are forced induction or more displacement.

Or otherwise, changing the gearing can make an incredible difference.

Also when the motor doesnt completely fall over on its face when you rev it some more, it definitely changes your driving style a bit.

I've owned this car for 8 years completely 100% stock, since 30,000km old and I've always driven it like a complete nanna. As it doesnt want to rev, so you end up shifting short anyway.

But when that top end power is available, you use it!

More so when C56 is fitted :D


My 1NZ-FE is the same way, I shift it at 2000rpm most of the time when I'm casually driving. I'm in 5th by 60-65km/h.