Noob Questions for a N/A or low boost build.

[Emeraldragon657]

Good afternoon fellow engine enthusiasts,
I am looking into doing a Cobra Kit at some point in the future, and am 99% sure I want to run a 1UZ-FE in it due to the inexpensive up-front cost of them (400$ CAD in my province) while still getting the distinct burble of a V8, and the snap and fuel economy of something with a lower displacement. As well as the unique-ness that comes with running a Lexus engine while everyone else is busy with thier LS's and 302's. My question is this, what are the best "Bang for your buck" mods on this motor, or just some things you learned while assembling/rebuilding your motor that you wish someone had told you before you started? I'm already thinking Headers and intake (ideally ITB's) will be my first mods after doing a full engine rebuild/refresh. How far can you take a stock ecu before you have to go aftermarket? Is Megasquirt worth looking into, or is it better to just pony up the cash for a already built one? Should I go for the older motor with thicker con-rods? Or is having VVT more important? I am a bit of a DIY'er, so not afraid to take on tedious tasks in the name of performance and driving feel. Hoping to end up in the 400HP-ish range. Also if I have to go boosted to get there, twin turbos or supercharger?

 

[P Bateman]

The stock ECU is fine for stock applications but once you start modifying, you will reach its limits fairly quickly.
Having the engine tuned correctly is the most critical part of any build - it doesn't matter how strong you build the internals, if it runs lean or the timing isn't right, it won't last long.

Bolt on mods (air filter, extractors, etc) will generally get you to 200-220hp at the wheels.
Anything more than this, I would start looking at an aftermarket ECU - especially if you're going to run ITBs.
I'm not a fan of Megasquirts or interceptor ECUs - if you're going to invest time and money into building your car, then don't skimp on the ECU. I highly recommend either a Haltech or Link ECU. You will also need to upgrade the pump, injectors and pressure regulator to suit the application.

Most guys running head porting, big cams, intake and exhaust mods are topping out around 300hp.
Yes, there are NA race engines that make a lot of power, but you'd need to rev the shit out of it, and streetability is questionable.
Add nitrous oxide and you're starting to get close to 400, depending how much your engine can take.

With boost, 400hp at the wheels is not a problem - I was able to achieve this on a 100% stock motor with a single T3 at around 14psi.
It has great low-end response, but it runs out of puff in the top end - I'm OK with this as it's a streetcar and I'm not ready to build the motor yet.
Twin T25/28's would give quick response and big top end. A single T4 is going to be slower to respond but deliver up top.
There has been some discussion here about twin T25 manifolds for a Cobra kit car.

I have no experience with supercharging a 1UZ, but many people here do, and they make solid dyno figures. There are several good kits around.

While some people have successfully run more boost on stock internals, others have also suffered head gasket failure past this pressure.
Steel head gaskets and ARP head studs solve this issue.

Whether you're going to run high revs NA, nitrous or boost, the early thick rod engines are preferable.
VVT is not important. The heads do flow more than (stock) non-VVT, but have weaker rods.
The lower efficiency of the non-VVT heads is easily overcome with positive intake pressure

PB

 

[Emeraldragon657]

The stock ECU is fine for stock applications but once you start modifying, you will reach its limits fairly quickly.
Having the engine tuned correctly is the most critical part of any build - it doesn't matter how strong you build the internals, if it runs lean or the timing isn't right, it won't last long.

Bolt on mods (air filter, extractors, etc) will generally get you to 200-220hp at the wheels.
Anything more than this, I would start looking at an aftermarket ECU - especially if you're going to run ITBs.
I'm not a fan of Megasquirts or interceptor ECUs - if you're going to invest time and money into building your car, then don't skimp on the ECU. I highly recommend either a Haltech or Link ECU. You will also need to upgrade the pump, injectors and pressure regulator to suit the application.

Most guys running head porting, big cams, intake and exhaust mods are topping out around 300hp.
Yes, there are NA race engines that make a lot of power, but you'd need to rev the shit out of it, and streetability is questionable.
Add nitrous oxide and you're starting to get close to 400, depending how much your engine can take.

With boost, 400hp at the wheels is not a problem - I was able to achieve this on a 100% stock motor with a single T3 at around 14psi.
It has great low-end response, but it runs out of puff in the top end - I'm OK with this as it's a streetcar and I'm not ready to build the motor yet.
Twin T25/28's would give quick response and big top end. A single T4 is going to be slower to respond but deliver up top.
There has been some discussion here about twin T25 manifolds for a Cobra kit car.

I have no experience with supercharging a 1UZ, but many people here do, and they make solid dyno figures. There are several good kits around.

While some people have successfully run more boost on stock internals, others have also suffered head gasket failure past this pressure.
Steel head gaskets and ARP head studs solve this issue.

Whether you're going to run high revs NA, nitrous or boost, the early thick rod engines are preferable.
VVT is not important. The heads do flow more than (stock) non-VVT, but have weaker rods.
The lower efficiency of the non-VVT heads is easily overcome with positive intake pressure

PB

Even for low boost the entire fueling system needs an upgrade? I'm glad to hear that your boosted motor has such good response, as that would be my only deterring factor from a turbo, going twins would likely improve response even more no? The fact that there's already a discussion about tt manifolds for a kit car is promising for sure. I was planning on going ARP on the initial refresh anyways. Are ITB's with boost worth it? The main reason it's on my mind is because I know part of the recipe for the RB26 having such great responsiveness is it's combination of twin turbos and itb's, that and looking under the hood and seeing itb stacks would be sick (though I suppose they would be camouflaged by the intake piping) Why stay away from megasquirt? I mean I understand that other options might be more user friendly, but there must be some support out there for it right? Especially when the price difference is close to 2000$ CAD, I could do decent internals for that kind of money.

 

[P Bateman]

Stock injectors are only good enough for around 300hp on low boost. There are several different types of injectors you can swap in, and you can read all about them here. You will need an aftermarket fuel pressure regulator that references boost, so that your fuel pressure doesn't drop. A Walbro Fuel pump is cheap insurance.

If response is a concern then supercharge it, as boost is virtually instant.
There will be lots of different opinions on turbos here - it all depends on where you want the power to arrive and how much room you have to mount it/them. When done right, little twins can see over 700hp... but so do Barra's with a single GT3584.

If you can afford to setup ITBs and they fit under the hood, then go for it. IMO, I would use the stock manifold and spend the money on a decent ECU. With a target of 400hp, the stock manifold won't be a limiting factor.

Why stay away from megasquirt? Because there are much better products available.
I would encourage you to have a good look at all the ECUs out there - compare the features, see what support is available, get advice from your local tuner, get some user feedback on the pros and cons, maybe even download the software and start building a map yourself.
In the end, it's your choice.

My experience with Haltech has been exceptional.

 

[Emeraldragon657]

Stock injectors are only good enough for around 300hp on low boost. There are several different types of injectors you can swap in, and you can read all about them here. You will need an aftermarket fuel pressure regulator that references boost, so that your fuel pressure doesn't drop. A Walbro Fuel pump is cheap insurance.

If response is a concern then supercharge it, as boost is virtually instant.
There will be lots of different opinions on turbos here - it all depends on where you want the power to arrive and how much room you have to mount it/them. When done right, little twins can see over 700hp... but so do Barra's with a single GT3584.

If you can afford to setup ITBs and they fit under the hood, then go for it. IMO, I would use the stock manifold and spend the money on a decent ECU. With a target of 400hp, the stock manifold won't be a limiting factor.

Why stay away from megasquirt? Because there are much better products available.
I would encourage you to have a good look at all the ECUs out there - compare the features, see what support is available, get advice from your local tuner, get some user feedback on the pros and cons, maybe even download the software and start building a map yourself.
In the end, it's your choice.

My experience with Haltech has been exceptional.

I suppose losing the itb's for a better ECU might be a good idea, especially since my local tuner is me haha. I live in the middle of nowhere Canada, so my nearest professional tuner is a solid 4 hour drive from home. Gotta do the math to see what size turbos I want, maybe the itb's will stay on the back burner as a "future upgrade". Is there anything I should know for doing a rebuild? I know some older engines like Ford Small Blocks have certain issues that should be addressed when rebuilding, such as improving flow through oil passages or replacing faulty stock valves, does this car have anything like that? Or is Lexus's legendary million mile motor just that good from the factory?

 

[P Bateman]

If you are tuning it yourself, this is where a better ECU helps. I am no tuner, but it was relatively easy to setup a base map and get the engine started. Based on the VE calculations, the software gave me safe fuel mixtures and conservative timing. Every time i drove it, the closed loop self tuning function trimmed the fuel down and by the time i got to the dyno, the tune was about 85% done.

For some tips on engine building, search for Skid Factory 1UZ on YouTube. They built one a few years ago (blue Ford) and gave excellent detail, tips and tricks.

 

[Emeraldragon657]

If you are tuning it yourself, this is where a better ECU helps. I am no tuner, but it was relatively easy to setup a base map and get the engine started. Based on the VE calculations, the software gave me safe fuel mixtures and conservative timing. Every time i drove it, the closed loop self tuning function trimmed the fuel down and by the time i got to the dyno, the tune was about 85% done.

For some tips on engine building, search for Skid Factory 1UZ on YouTube. They built one a few years ago (blue Ford) and gave excellent detail, tips and tricks.

Thanks man, this has been a lot of incredible info! I think you've managed to answer all the questions I could come up with

 

[Emeraldragon657]

If you are tuning it yourself, this is where a better ECU helps. I am no tuner, but it was relatively easy to setup a base map and get the engine started. Based on the VE calculations, the software gave me safe fuel mixtures and conservative timing. Every time i drove it, the closed loop self tuning function trimmed the fuel down and by the time i got to the dyno, the tune was about 85% done.

For some tips on engine building, search for Skid Factory 1UZ on YouTube. They built one a few years ago (blue Ford) and gave excellent detail, tips and tricks.

Actually I came up with a couple more questions, are there any mods for a 1uz that increase torque? And how far can you rev stock cams?