240Z L28ET project

[bucket240z]

When the engine is actually in the car it will be mighty difficult to get the exhaust manifold off with the intake still on.

[Gollum]

Some notes I wrote down in my head while reading this thread:

 

Blow off Valve - I'd suggest a recirculating type that moves air into the intake, because this is a AFM system in which air is metered by way of passage through a sensor, not MAP based off of air pressure in the manifold.

 

What this means is that when your blow off activates and throws air into the atmosphere in this AFM setup, you're not pumping fuel for air that no longer exists. The air has already been counted, so the fuel must be used. This means you'll go extremely rich under those rapid throttle decreases. Using a recirculating BOV will just mean the motor doesn't drop in revs all that fast, as air will still be getting past the trottle when you let off quickly.

 

And as far as the Z31 turbo. Sure you COULD use the Z31 wiring and such, but I don't really see a point. If you're gonna do a wiring/ecu swap I'd go the full 9 yards and do the late Z31, or Z32 swap and install a romulator so you can tune it.

 

There isn't much of a point in upgrading the wiring/ecu and keeping the AFM that chokes the car's responce.

 

The only thing that NEEDS to be done for the Z31 turbo conversion (that I'm aware of) is you need to plumb a water source to it, since it's water cooled. This shouldn't be too hard, as there's already a water source that heads to the trottle body in the L28ET (and L28E). Most people bypass it anyways since they don't live in climates that they're worried about the throttle freezing at all, but you could just pump some new lines off of those to the turbo. I'm not sure how others do the swap though.

 

I've currently got a L28ET in a S30 (75' 280Z) so if you need pictures of how the swap was done just let me know. I bought the car less than a month ago with the swap already done, and I don't think it's the best quality swap out there, but it could give you an idea or two.

[MazterDizazter]

Yes, I agree. My MR2 Turbo had a non-recirculating BOV and it was a mistake; I would autocross it and every time I'd lift off throttle and get right back on it again, the car would become very unsettled. Any idea if the GReddy RS is a recirculating type? I just happen to have one lying around

[Gollum]

I don't think it is, but the only thing that really makes a BOV a recirculating type is that it has a connection to easily hook up to plumbing to route the air to the intake.

 

So if you had someone weld a nozzle onto the "exhaust" of the BOV then you could plumb it into the intake.

 

For an examble of a BOV designed for recirculation:

 

http://www.turboxs.com/more_info.php?ID=7

 

That's similar to the one I plan on getting for my car once I get an intercooler setup, which could still very well be more than a year out for me.

[MazterDizazter]

Hmm, alright I'll do some more research.

 

I started degreasing the engine today. Look at the difference!

Before:

After:

Before:

After:

[MazterDizazter]

The valve cover came out nicely; I was gonna replace it but I think I'll keep it at least for now:

 

The front is going to need a LOT more work:

[MazterDizazter]

Well, I'm on spring break this week, which really isn't a break at all since I'll be splitting my time between my job and working on the car, but I'm pretty excited. My gas tank came in yesterday, and my flywheel, intake manifold, and injectors should be coming in soon!

[Six_Shooter]

As long as the BOV remains closed in high vacuum conditions, as in idle, it doesn't need to be a recirculating type. This is because the onlytime it needs to open, and should open is when the throttle is closed after being in boost. At this point the fuel delivery should be cut off or severly reduced, sice an engine in decel (I'm speaking engine only here), doesn't need ANY fuel to slow down. So venting the excess presurized air to atmosphere will not effect the fueling, or cause it to go excessivly rich as it was once believed to do. The engine will go rich at this point anyway, since it takes time between letting off the throttle, to the fuel that was being injected that second to make it way through the engine, and out the exhaust past the O2 sensor.

This is of course if the fuel decel tables are set up this way in the Nissan ECU, my experiance is with GM ECMs, and very limited exposure to a few others, most seem to cut fuel in very similar ways though.

In driving where there is a lot of on and off the throttle transitions, such as auto-x as mentioned, a recirulating type might work better, but it doesn't seem to be a definate thing as there are people that use both styles in all forms of racing or driving styles, and have benefits to both and draw backs to both.

[Gollum]

The nissan ECU only cuts above 2500, and needs a full 100% throttle cut in order to work. There will be times that you're feathering throttle so fast that draining that air to atmoshere is just plain a waste of time. Leaving the air going into the engine will give you a more quicker throttle responce as the mixture gets in range faster, and the intake is already charged with air and isn't creating as intense of a vacuume.

 

For a street driven car either works imo, but if you're going to be doing any type of racing with turns in it I think you're better off not chancing it. Just do it right the first time. I think there's a reason why pretty much all OEM turbo cars use a recirculating type BOV, even the brand new and redesigned STIs and EVOs.

[Six_Shooter]

The nissan ECU only cuts above 2500, and needs a full 100% throttle cut in order to work. There will be times that you're feathering throttle so fast that draining that air to atmoshere is just plain a waste of time. Leaving the air going into the engine will give you a more quicker throttle responce as the mixture gets in range faster, and the intake is already charged with air and isn't creating as intense of a vacuume.

 

Wow, that's pretty high to have the fuel enable come back in. In the ECMs that I'm used to seeing the parameters for the fuel enable is much lower, and the throttle position doesn't have to be 0%, though I imaging that the Nissan ECM needs to see a closed throttle because of the TPS switch, instead of a sensor, at least the early Nissan TPS is this way, not sure about the ZX or ZXT TPS, as I haven't really found any information on that.

 

For a street driven car either works imo, but if you're going to be doing any type of racing with turns in it I think you're better off not chancing it. Just do it right the first time. I think there's a reason why pretty much all OEM turbo cars use a recirculating type BOV, even the brand new and redesigned STIs and EVOs.

 

Most of the aftermarket systems go to a vent to atmoshpere, even the Factory authorized BOV from Mopar performance for the SRT4 is a vent to atmosphere, so I wouldn't necessairly say one way is right and one is wrong, they just do things a little differently.

 

One reason I can see the OEM BOVs being a recirculating type is for emissions, in that most emmisions laws state that there can be no "open elements filters" or any "emmissions control system vented to atmosphere", and anything after the air filter would be considered part of the emmissions control system.

 

The "need" to recirculate would also depend on where the MAF is located, I have only seen flapper door AFMs used on early Nissans so that would need to be before the turbo, on later model MAF systems, the MAF can be placed post compressor housing, and then the BOV, as long as it's pre-MAF can be open to atmospher without effecting any reading of the MAF.

[Gollum]

Isn't the SRT4 MAP based, thus negating any worry about richness off boost?

 

Though I believe the STI is map based as well.

 

As far as I know ALL the L series TPS "sensors" are switches. So that combined with the high fuel cut you should be able to see why I'd suggest a recirc type for this particular application.

 

Sorry if I ever seemed to be making general statements. If we were talking about a different motor, or even an L series running a MAP based megasquirt my advice would probably have been different.

[MazterDizazter]

Well for now I'm going to use a GReddy RS BOV because I already own it, and if it becomes a nuisance I'll replace it with a recirculating type. I got my car out of storage today, w00t! I'll be pulling the motor tomorrow morning, and I hope to have it done by noon so I can start cleaning out the engine bay. I am gonna miss my triple Webers!!!

[Daeron]

dorky point of order:

 

TPS stands for two different things;

 

Throttle Position Switch (L-series type, two contact switch)

and

Throttle Position Sensor (potentiometer-style, resistance based sensor. think a volume knob)

 

Now, I realize that almost everyone knows the difference.. but it often makes life easier to say TP Switch, throttle switch, etc or throttle sensor just to avoid confusion.

 

On a side note, I am 99.99% positive that All l-series FI used switches, not sensors.

[MazterDizazter]

Can anyone answer me how to switch from low impedance to high impedance injectors? I asked in the fuel delivery forum but got no answers and it's driving me nuts! I want to use 295cc Supra injectors because they'd only be 30cc's larger so I don't think they'd make a humongous difference, and they'd allow me to use a Pallnet fuel rail for 11mm injectors. This would allow me to easily upgrade to larger injectors in the future, without changing fuel rails.

[MazterDizazter]

I got some parts in from MSA today: BRE rear spoiler, clear headlight covers, Cusco oil catch can, and two polished block-off plates. I also got my Fidanza flywheel and Supra 295cc injectors in, and should be getting my downpipe and ported intake manifold in soon. Here's some pics:

[MazterDizazter]

I also got some more cleaning done on the engine tonight. 26 years of grime is a PITA to remove! I'm not looking for car show-winning cleanliness, just clean enough to work with. It will get a major cleaning when I get it rebuilt, probably next year.

 

 

 

My shiny new polished block-off plates...if only the rest of the engine could be so shiny.

 

 

When I get a full gasket kit in, I'm going to take all the accessories off the front and give them a proper cleaning. It's just not working with everything assembled.

[MazterDizazter]

Just a small update: I got my downpipe in and bought an engine stand at Autozone so I could get the engine off the pallet and work with it more easily. Cost me just under $75, with a trip to Lowes to get bolts and washers to mount the engine. Now I'll be able to turn it upside down when I need to replace the oil pan. I'll be ordering a gasket kit shortly, and once I replace the major gaskets I can start putting everything together. The transmission should hopefully be ready in a week or two if everything's on time.

Also, I may be purchasing a Megasquirt kit which will further delay the time it'll take me to get the car finished, since I'll have to research and buy a new turbo and injectors, at the very least. I may choose to wait however since my budget is very limited to what I already listed, plus possibly new struts and springs, new Autometer gauges, and an aftermarket bucket seat. We'll see how that ends up.

[gsr355]

Where did you get the block off plates from? I need to get some for my swap also. Thanks.

[MazterDizazter]

got them from Motorsport Auto. Here's the direct link: http://www.thezstore.com/page/TZS/CTGY/saleengdress

[Daeron]

Just a small update: I got my downpipe in and bought an engine stand at Autozone so I could get the engine off the pallet and work with it more easily. Cost me just under $75, with a trip to Lowes to get bolts and washers to mount the engine. Now I'll be able to turn it upside down when I need to replace the oil pan. I'll be ordering a gasket kit shortly, and once I replace the major gaskets I can start putting everything together. The transmission should hopefully be ready in a week or two if everything's on time.

Also, I may be purchasing a Megasquirt kit which will further delay the time it'll take me to get the car finished, since I'll have to research and buy a new turbo and injectors, at the very least. I may choose to wait however since my budget is very limited to what I already listed, plus possibly new struts and springs, new Autometer gauges, and an aftermarket bucket seat. We'll see how that ends up.

 

To the best of my understanding, installing standalone fuel injection is not, in and of itself, cause to immediately go buy new, larger injectors and turbocharger to complement it. As far as I have gathered (internet bookworm, not speaking from experience disclaimer) there is a significant amount of room for growth for the L28ET to be found in the engine management alone. You will need to upgrade to a MAP sensor instead of your AFM, (for megasquirt) and the airflow meter is as much of an impedance on the air intake as the stock throttle body. (Granted, the stock intake manifold is probably as much of an impedance as well.. but it can still make plenty of power.)

 

Larger injectors are a relatively easy replacement anywhere down the line; they are right up there on top of everything else. The turbo can be played with until you get tired of it.

 

I would suggest simply installing what you have, and then playing with more fuel and bigger turbo as a preliminary incentive to blowing and rebuilding your engine. It sounds like you plan on rebuilding shortly anyhow, so I say that tongue-in-cheek

 

 

It looks like you've got the disease; I don't know whether to congratulate you or pity you