DIY ITB

[gav240z]

Buy an RB25. It may end up costing $500+ than setting up ITB's, but you will have a newer engine with perks over the 'L'egacy series engine that's currently sitting in your engine bay.

 

Scoota G should be able to work something out for you if you're serious.

 

Yeah but where is the fun in that?

 

I'm interested to see how you guys go, I want to try building a Megasquirt EFI set up on my 240z. I hear what you guys are saying in terms of it being a headache but I'm very eager to learn.

[Six_Shooter]

Wow, lots of ney-sayers here.

 

I realize that the cost of living is a little higher in Australia, compared to here, but it's all relative, I also believe that pay is higher as well...

 

That being said there is a lot of advice that is being spout as "required" and "the only way to do it" when it's not. There are many ways to accomplish this, and it's usually only after you have built and installed several set-ups that it becomes clear how to do it easily, it's that experience thing.

 

For the record I have built or been involved in building and tuning several custom EFI systems, for engines that never had EFI, to conversions from difficult to tune EFI to easier systems.

 

I tend to use Delco (GM), that would be Holden for you guys ECMs for my conversions. They are plentiful, they are cheap, and they are extremely reliable. They are also easy to tune, and can be done cheaply, if you don't care about real time tuning, also included is onboard diagnostics. I am running my turbo L28 on a Delco ECM and have for about 5 years, works great. Why am I bringing this up? People tend to "Oh I have to go aftermarket to inject my old engine". No, no you don't, you can adapt other OEM EFI, and the great part about that is that the parent companies have spent Millions on development, to make sure they are reliable and perform well. The DIY community then takes these and hacks them for tuneability and adding features.

 

Personally I'm using OBD1 ECM, that is running wastespark DIS and bath fire injection, this was cheap, reliable and don't need "credits" to tune it. I could have easily went to an OBD2 ECM that would allow for SFI, but it's just not needed.

 

Thanks for the "option #3" link, I was not aware of this company and I think I will use these parts for my planned custom ITB conversion on a V6 engine I plan to use.

 

Getting a solid map signal is not that difficult, especially since you will be making a manifold or modifying and exiting one. You can run a tube from each runner below the throttle blade (but above the injector), to a common vacuum block, that is then fed to the MAP sensor. If you want to use an IAC valve, you need to replicate this set-up again, and have a separate block for the IAC valve. The reason for this is to not affect the MAP signal with the IAC valve directly. I do know of one person that made both work on a common IAC/vacuum plenum, but it was definitely not ideal.

 

Spark triggering and control is not that difficult either. When I first installed my system I ran out of time to get the DIS in off the bat, and so I used an electronic dizzy from an L28, from a '77 or so. I locked out the mechanical and vacuum advance. I then triggered a GM ignition control module, that fed the DRP (Distributor Reference Pulse, AKA RPM reference) and allowed the ECM to control the timing of the ignition. I then swapped in my DIS the following winter, that involved a custom (pretty simple) trigger wheel, using the same ECM, with a couple settings changed for the DIS offset. Aftermarket systems also have this ability. Some systems have the ability to have sequential spark control in addition to sequential injection, such as the Megasquirt 3.

 

If this was my first build, I'd do plenty of research, but I would hold off buying the ECM part, if I was going aftermarket, until most of the mechanical part was squared away. The reason for this is that the aftermarket changes so often, that the ECM you buy today may be "obsolete" next year, or at least a "better", "more improved" version may be available, that may work better for you. If I was going with an OEM set-up, such as what I like to do, then grabbing the ECM and related hardware can be done at anytime. I would plan which system I wanted to start with, even if the plan was to hold off on buying it. The reason for this is that certain ECMs will only work with certain hardware. Again, I'll go back to my Delco (GM) ECM, the ignition is easiest to interface with GM parts, due to the signals between the ICM (Ignition Control Module) and the ECM being somewhat specific. Going aftermarket you can usually use just about anything you can get your hands on, with a few exceptions. I do know of a universal adapter that is said to allow any ignition system to be used with a Delco ECM though. I'm not sure if it's released to the public yet though.

 

Other sensors and such, are less incidental, since most will use the same threads to attach, or be easily adapted, like coolant temp, manifold temp, TPS, etc, with a few specific exceptions, again researching what you want to use as a system, will make this easier in the end.

 

I always find it entertaining when people say "You NEED to dyno tune your set-up". Why? Are you driving your car on a dyno? I'm not, I'm driving mine on the street, so that's where I tune it. A dyno is great if you want to get max power numbers, but does next to nothing for driveability. Even "load cell dynos" will only get the tune so close. The best data is retrieved from where and how the vehicle will be driven. This is why I tune on a drive around the city and highway as the vehicle will be used. When I tune for other people I sit in the passenger seat and tell them to drive as they normally would to get a tune that suits that person. I do get the driver to drive in certain ways sometimes just to get into certain load points and RPM points that wouldn't normally be hit, just to get a wider range of tune, but that only usually happens when there seems to be a small hurdle to get tuned out.

 

Real time tuning is great and is one element I look for when deciding on an ECM to use, again this is another reason I like my Delco ECMs, with an EPROM Emulator, I have real time tuning that I can see the changes immediately as they are made. Obviously if I'm driving, I do it the old way of looking at logs or rather, keep track of what happened and when, pull over, make a change and re-test.

 

With careful planning an EFI system that works great, is reliable and is inexpensive can me put together.

[juz0]

I've actually had an ITB set up finished using a triple weber manifold and rb26 itb's.

Unless you can do the machining and welding yourself its cheaper to buy a ready made kit.

I'm pretty sure my total cost just for the itb setup is around 3k and the biggest cost was getting it all together and set up.

If i was doing this again I would just buy an OER kit.

 

I still have to buy an ECU, different injectors, coil packs, make the wiring loom etc etc.

It's not a cheap conversion!

 

for the trigger I've got an L28et dizzy with optical disc.

should work alright once it's all together

 

take a look at my last post on this thread and you can see what it looks like

 

http://www.viczcar.com/forum/index.php/topic,12893.msg138049.html#msg138049

 

good luck!

[DreamZproject]

Woooooow. Several amazing replies here!

Yes there's still more for me to learn, but I've been pointed in the right direction no doubt!

I'm sure I'll come back to this thread in a couple of weeks and a few more questions, but

This is FANTASTIC!

Thank you very much for the time guys! I feel somewhat more confident in going ahead with

This at some point in the near future.

[1600dave]

Buy an RB25. It may end up costing $500+ than setting up ITB's,

 

Buy an R33 skyline, it'll be way less than buying / modifying / maintaining an old zed 

 

I'll see if I can find my set of Toyota ITB's and measure for you - I vaguely recall that they weren't far off / may have been the same as webber pattern ? I could be wrong, its been a while.

[53-681]

Buy an R33 skyline, it'll be way less than buying / modifying / maintaining an old zed 

 

Buy a bicycle, it'll be way less than buying / modifying / maintaining a car.

 

What are you implying? That a half assed mod is superior to an engine conversion?

 

If you're really that keen on being a Datsun/Z-Car enthusiast; you would retain the vehicles 'original' parts. In this case the original fuel system being the twin flat top carburetors with the air box.

 

 

[Six_Shooter]

If you're really that keen on being a Datsun/Z-Car enthusiast; you would retain the vehicles 'original' parts. In this case the original fuel system being the twin flat top carburetors with the air box.

 

I don't agree with this statement.

 

I love my Datsun Z-car, but I will never leave it stock, which I haven't. I also have many more modifications planned, most that will not be seen.

[DreamZproject]

Original or not (I do see both points) doing it this way means I don't have to get the thing engineered = less money and

Stuffing around, plus I can drive it whilst still on my P's.

I also want a really nice sounding engine, and I've never heard an RB that I like the sound of...

[luvemfast]

Why go ITB's at all?

For what you want, an L28 manifold with the big plenum will suffice!

[1600dave]

Buy a bicycle, it'll be way less than buying / modifying / maintaining a car.

 

What are you implying? That a half assed mod is superior to an engine conversion?

 

If you're really that keen on being a Datsun/Z-Car enthusiast; you would retain the vehicles 'original' parts. In this case the original fuel system being the twin flat top carburetors with the air box.

 

Sorry, just a flippant comment.

 

Perhaps a half assed mod (or maybe even a well-engineered mod if he gets some good advice to his original question) may be what the original poster wants.

 

Anyway, a bit of info.

 

Toyota ITB's come in two sizes apparently, mine have a 42mm butterfly (don't know if these are the larger or smaller ones). They are set on 88mm centres, weber flanges are on 90mm centres. "bolt pattern" on the flanges of the Toyota throttle bodies and webers are also different. What this does mean however, is the it should be simple enough to use a "spacer" of aluminium to adapt both the bolt pattern and the centre spacing of the Toyota ITB's to a weber manifold.

 

The Toyota ones are true "individual" throttle bodies - ie 4xthrottle rather than 2 lots of 2 like weber carbs, so you may be able to spread the carbs out a few mm to match the weber flange spacing (depending on how the linkages, etc, will handle being a few mm further apart). This only matters for the "pairs" of throttle bodies that end up next to each other (ie that replace a weber carb), you will still need to work out how to sort the linkages to spread the "pairs" further apart - how far apart will probably depend on what weber manifold you use.

 

So, just cut the spacer to size, bolt it onto the weber manifold, a little judicious shaping to take up the few mm of difference in spacing if needed, and then bolt the Toyota ITB's onto the other side of the spacer. You may also be able to incorporate the injector bosses into the spacer, although personally I'd weld them onto the manifold closer to the head. Easy ! Well, getting the ITB's onto the engine is easy - as others point out, there is still a lot to sort out before you get your L-series running.

[Zedman240®]

If you want to hear a nice RB, youtube any Rocky Auto carbed RB and it will change your mind....

[DreamZproject]

Oh I'm sure a carbd rb would sound fantastic!

I couldn't imagine how hard it would be to get engineered.

Great info guys, yes perhaps an aftermarket intake plenum would be the way to go...

I'll cost up everything for itbs and then compare it.

[d3c0y]

You can't. Carb twin cam RB is illegal.

[luvemfast]

You can't. Carb twin cam RB is illegal.

What about a Carb, twin cam L series? 

[d3c0y]

No that is legal as you go off the block not the head! 

[gav240z]

Carb RB30 Twin Cam?

 

Wasn't there an RB30 that was fed by a carby?

[d3c0y]

Yeah that would work and just put a twin cam head on it same same.

[44014]

Yep! The rb30 patrol had points and a carb.

Was not very spirited to drive...

[d3c0y]

Gav said with a twin cam head, i'm thinking it would be pretty spirited.

[DreamZproject]

Haha that sounds fantastic! Anyone want to make one for me?

Sure I have a spare 20k lying around...

[d3c0y]

what about the rest of the money?

[DreamZproject]

Wow, lots of ney-sayers here.

 

I realize that the cost of living is a little higher in Australia, compared to here, but it's all relative, I also believe that pay is higher as well...

 

That being said there is a lot of advice that is being spout as "required" and "the only way to do it" when it's not. There are many ways to accomplish this, and it's usually only after you have built and installed several set-ups that it becomes clear how to do it easily, it's that experience thing.

 

For the record I have built or been involved in building and tuning several custom EFI systems, for engines that never had EFI, to conversions from difficult to tune EFI to easier systems.

 

I tend to use Delco (GM), that would be Holden for you guys ECMs for my conversions. They are plentiful, they are cheap, and they are extremely reliable. They are also easy to tune, and can be done cheaply, if you don't care about real time tuning, also included is onboard diagnostics. I am running my turbo L28 on a Delco ECM and have for about 5 years, works great. Why am I bringing this up? People tend to "Oh I have to go aftermarket to inject my old engine". No, no you don't, you can adapt other OEM EFI, and the great part about that is that the parent companies have spent Millions on development, to make sure they are reliable and perform well. The DIY community then takes these and hacks them for tuneability and adding features.

 

Personally I'm using OBD1 ECM, that is running wastespark DIS and bath fire injection, this was cheap, reliable and don't need "credits" to tune it. I could have easily went to an OBD2 ECM that would allow for SFI, but it's just not needed.

 

Thanks for the "option #3" link, I was not aware of this company and I think I will use these parts for my planned custom ITB conversion on a V6 engine I plan to use.

 

Getting a solid map signal is not that difficult, especially since you will be making a manifold or modifying and exiting one. You can run a tube from each runner below the throttle blade (but above the injector), to a common vacuum block, that is then fed to the MAP sensor. If you want to use an IAC valve, you need to replicate this set-up again, and have a separate block for the IAC valve. The reason for this is to not affect the MAP signal with the IAC valve directly. I do know of one person that made both work on a common IAC/vacuum plenum, but it was definitely not ideal.

 

Spark triggering and control is not that difficult either. When I first installed my system I ran out of time to get the DIS in off the bat, and so I used an electronic dizzy from an L28, from a '77 or so. I locked out the mechanical and vacuum advance. I then triggered a GM ignition control module, that fed the DRP (Distributor Reference Pulse, AKA RPM reference) and allowed the ECM to control the timing of the ignition. I then swapped in my DIS the following winter, that involved a custom (pretty simple) trigger wheel, using the same ECM, with a couple settings changed for the DIS offset. Aftermarket systems also have this ability. Some systems have the ability to have sequential spark control in addition to sequential injection, such as the Megasquirt 3.

 

If this was my first build, I'd do plenty of research, but I would hold off buying the ECM part, if I was going aftermarket, until most of the mechanical part was squared away. The reason for this is that the aftermarket changes so often, that the ECM you buy today may be "obsolete" next year, or at least a "better", "more improved" version may be available, that may work better for you. If I was going with an OEM set-up, such as what I like to do, then grabbing the ECM and related hardware can be done at anytime. I would plan which system I wanted to start with, even if the plan was to hold off on buying it. The reason for this is that certain ECMs will only work with certain hardware. Again, I'll go back to my Delco (GM) ECM, the ignition is easiest to interface with GM parts, due to the signals between the ICM (Ignition Control Module) and the ECM being somewhat specific. Going aftermarket you can usually use just about anything you can get your hands on, with a few exceptions. I do know of a universal adapter that is said to allow any ignition system to be used with a Delco ECM though. I'm not sure if it's released to the public yet though.

 

Other sensors and such, are less incidental, since most will use the same threads to attach, or be easily adapted, like coolant temp, manifold temp, TPS, etc, with a few specific exceptions, again researching what you want to use as a system, will make this easier in the end.

 

I always find it entertaining when people say "You NEED to dyno tune your set-up". Why? Are you driving your car on a dyno? I'm not, I'm driving mine on the street, so that's where I tune it. A dyno is great if you want to get max power numbers, but does next to nothing for driveability. Even "load cell dynos" will only get the tune so close. The best data is retrieved from where and how the vehicle will be driven. This is why I tune on a drive around the city and highway as the vehicle will be used. When I tune for other people I sit in the passenger seat and tell them to drive as they normally would to get a tune that suits that person. I do get the driver to drive in certain ways sometimes just to get into certain load points and RPM points that wouldn't normally be hit, just to get a wider range of tune, but that only usually happens when there seems to be a small hurdle to get tuned out.

 

Real time tuning is great and is one element I look for when deciding on an ECM to use, again this is another reason I like my Delco ECMs, with an EPROM Emulator, I have real time tuning that I can see the changes immediately as they are made. Obviously if I'm driving, I do it the old way of looking at logs or rather, keep track of what happened and when, pull over, make a change and re-test.

 

With careful planning an EFI system that works great, is reliable and is inexpensive can me put together.

 

Six_shooter I've thought about it for a while, and what you're saying makes a ton of sense. I think that this might be the path I'm going to go down.

There's heaps more i need to research, but just costing it up, this way seems to make sense. I don't need a hyper tuneable machine. Just something

that is a bit special.

 

The idea of using another cars ECU is ingenious! With the Delco ECM's, are car tuners familiar with interfacing with them? I have no clue on tuning cars

and i think that it may be something that is not worth my while spending hundreds of hours learning.

 

What is the advantage/ disadvantage of going DIS over using the L28ET dizzy with this sort of setup?

 

Costs; (partly second hand parts)

ITB's + injector bungs from racehead.com $750

DCOE Manifold $300???

LS1 coils $100 (wow they can be found cheap)

Leads $100

Delco ecm + harness $100?

EFI fuel pump etc. 

Injectors 

various sensors $150

Tuning $300

 

This looking right so far?

[nizm0zed]

I have a box full of Delco stuff, ECU's, throttle bodies, woring loom and plugs ect ect, and a Kalmaker SP3 fully programmable Delco ECU.

If your interested i'll get some pics over the weekend and send them to you?

[Six_Shooter]

Six_shooter I've thought about it for a while, and what you're saying makes a ton of sense. I think that this might be the path I'm going to go down.

There's heaps more i need to research, but just costing it up, this way seems to make sense. I don't need a hyper tuneable machine. Just something

that is a bit special.

 

The idea of using another cars ECU is ingenious! With the Delco ECM's, are car tuners familiar with interfacing with them? I have no clue on tuning cars

and i think that it may be something that is not worth my while spending hundreds of hours learning.

 

What is the advantage/ disadvantage of going DIS over using the L28ET dizzy with this sort of setup?

 

Costs; (partly second hand parts)

ITB's + injector bungs from racehead.com $750

DCOE Manifold $300???

LS1 coils $100 (wow they can be found cheap)

Leads $100

Delco ecm + harness $100?

EFI fuel pump etc. 

Injectors 

various sensors $150

Tuning $300

 

This looking right so far?

 

Ok, well if you use the OBD1 Delco stuff you won't really be able to use the LSI coils.

 

The LS1 coils are meant to be triggered directly from the ECM/PCM, the OBD1 is not set up this way, and requires an Ignition Control Module for this purpose, and also to tell the ECM when the engine is running and at what RPM. I can go into more detail, but it's not important right now. Suffice it to say this is why you need to research how things work together BEFORE buying anything.

 

Before I get into the advantages of DIS, I will also say that the L28ET will not work with the OBD1 Delco ECM either. The L28ET, while it was an improvement in control for the Nissan systems would provide no advantage when using a Delco EFI system, if it would even work. The problem here is that the L28ET dizzy uses an optical sensor, which does not interface (directly) with a GM ICM. The standard L28 electronic dizzy is perfect here, cheaper and easier to get a hold of. The only thing needed is to lock out the mechanical and vacuum advance. Though, thinking about it as I type this, you could set the ignition tables in the ECM to a value (possibly zero, I would have think about this), and let the dizzy do timing control, but then you're throwing away about 60% of what the ECM can do. Best IMO just to lock out the dizzy, if you are using a dizzy. I can link to an article on how to use the non-efi GM ECM with an L-series, the only difference becomes the 4 wires that connect to the ECM.

 

The advantages of DIS is that there are no moving parts to wear out, no contacts to wear down., you gain more precise spark control and hotter spark, since each coil can be charged longer than single coil system. You can also choose where to mount the coils, to possibly clean up the engine bay. I use an ICM and coil system from the gen II/III 60 degree V6, which is a FWD V6 found in many North American GM vehicles, I'm not aware of Australia getting these engines, but the 3800 style DIS systems are similar, and can be used for a conversion such as this.

 

The popular ECM to use in Australia for these types of conversion seems to be the '808, and I know these have been used with the 3800 style ignition system.

 

There is a device made by an Australian bloke that is meant to be a more universal Ignition Control Module to use virtually any trigger wheel available, and interface with the Delco ECM, but I am not sure if this is available to the public yet or not.

 

The only real fabrication here the trigger wheel that you will need to mount to the front of the crank pulley. It is slightly different between different GM ignition systems in notch layout and count, but I will attach pictures of mine to this post, to give you an idea.

 

As far as tuners being able to interface with the Delco ECM, it depends on what ECM specifically and what your local tuners are comfortable with. I'm one of the few around me that will tune the OBD1 Delco stuff, most people only do the OBD2, probably since there are more OBD2 vehicles around than OBD1, and there's no real hardware needed for ODB2, but there are limitations. I prefer my OBD1 tuning.

 

If you seriously want to look into the Delco I can link you to a couple of sites, one is based in Australia, the other is a site I helped to start.

 

Australia based Delco tuning forum (though they are expanding out from there):

http://pcmhacking.net/forums/

 

The one I help run, which seems to have mostly Delco people, though we do not discriminate:

http://www.gearhead-efi.com/

[DreamZproject]

Ok, sounds good so far... one thing i am a little confused about with a DIS setup... What is a 3800 style DIS?

Which car am I pulling these from? is this the same gear that i would pull off an LS1?