Fuel Injection Upgrade from Carbs

[Buffalo_Z]

So I've been wondering, even though I am still early in the restoration of my Z, if it would be of much benefit to switch to a later model FI system later on. My 73 240 came with an L28 from an 83 ZX, headers, and round top carbs. That seems like a good setup from everything I have read, but I'm wondering if there wouldn't be a performance and maintenance benefit to eventually upgrading to fuel injection from a later model car. If I did, I would want to take a stock system from a ZX and remove all of the emissions equipment so that it doesn't look like a rat's nest and add a lot of extra complexity. I also don't want to bother with a complete turbo upgrade.

 

Has anyone else undertaken something like this?

 

Thanks,

 

Matt

[Six_Shooter]

From what you posted, I would stay with the carbs.

 

Don't get me wrong, I love my EFI, but if both are tuned well, there should be insignificant performance differences and the amount of time and money you put into maintenance might be about the same, in the long run.

 

If the EFI upgrade used something other than the stock electronics, you could pull some better driveability and fuel economy out of it, but the stock system is pretty crude, though it does get the job done.

Edited May 18, 2012 by Six_Shooter

[OldAndyAndTheSea]

I've just completed this swap in my 73 240z.

 

My reasoning behind this was due to the fact that my carb bodies were very worn, and I required new cores to continue. Plus I am eventually turbocharging my motor and this was the first big step in doing so, although this doesn't apply to you.

 

I used the FI system from a 1975 280z. I am very pleased with the result. I will say I have absolutely noticed an increase in reliability, and obviously cold starts happen much easier. Considering you are in the Buffalo area, this is a concern for you as well (I went to Buff State by the way). As previously posted, the carbs, if fresh and well tuned, will give very little problems and can be daily driven. But if you are having trouble with the carbs, and keeping them tuned, this is probably an indication of needing a rebuild, or your 40 year old units are just past their prime. You could always get a pair of Ztherapy carbs and call it a day and be driving soon. But if you are considering the swap here are a couple things to think about

 

Things to think about with the swap:

 

The gas tank and fuel system will need to be addressed. Since the 240z gas tank does not have baffles, it should be swapped out for either a 280z tank (must be 75-76 non space saver tank) or a fuel cell (overkill in my opinion for a daily driver/street driven car.)

 

The stock return line will not be sufficient for a fuel injected application. I replaced the stock 3/16'' return line with a 5/16'' hard line. And I am using a Walbro 255 inline fuel pump.

 

and obviously you will require the FI components (intake/afm/engine harness etc...) Google: "Datsun Fuel injection bible" for a complete list of the parts needed, and how they operate.

 

performance wise, I would agree with Six_Shooter, you wont see any real significant changes (unless your current system is not running properly). The biggest difference I have noticed, aside from the easier cold starts is throttle response. This was a HUGE plus for me. I am thrilled with how my system came out and if you want to check it out, I have documented my entire swap from carbs to FI in my build thread (link is in my signature). I too used all NON emissions stuff.

 

Let me know if you have any questions regarding the conversion, I will be glad to help out.

 

Best regards,

 

Andy

Edited May 18, 2012 by OldAndyAndTheSea

[Buffalo_Z]

Thanks for the detailed feedback, I appreciate it. Sounds like I am better off with carbs for awhile. I grew up fixing lawnmowers, so I have the right background for them anyway.

[Pharaohabq]

BuffaloZ, Yeah, It's a pain to upgrade to EFI. If you were going to do so, I'd suggest you do the EFI swap to Megasquirt+spark so you can get more efficient control of your injectors/engine. You should get good power, and easier starting, but you won't see a huge difference in power over carbs. You will likely still have some fuel fumes too.

 

Another possibility is going with the Nissan EFI system out of an 86+ 300zx, it uses a MAP sensor and an AFM. it's pretty efficient and has been done on a L28.

 

Something I've really wanted to do is try out the 94 GM EFI system on an L28. Check out HESCO EFI conversion You won't need the full kit, just the harness, you can get a computer cheap on Ebay, and the CPS might work from the Jeep, but if not then There's a guy on here who made a bolt on timing wheel that would work. The advantage is Multi port injection, and the MAP/CPS/O2 sensor automatically tunes the emgine w/o needing an AFM or the bulky datsun flappy afm. The system worked great on my Jeep. But just it's a 4.2L, and I used a ton of junkyard parts, but I'm 100% certain it could be adapted to the L28 since the same GM computer runs both the GM 2.3L and the 4.2L inline 6 cyl engines. you can read about my EFI system on my ProjectJeep site.

 

If you need help, I'd love to help you figure this one out.

 

Phar

[Six_Shooter]

I'm using GM EFI on my turbo L28, have been for about 4 years.

[michaelp]

I've just completed this swap in my 73 240z.

 

My reasoning behind this was due to the fact that my carb bodies were very worn, and I required new cores to continue. Plus I am eventually turbocharging my motor and this was the first big step in doing so, although this doesn't apply to you.

 

I used the FI system from a 1975 280z. I am very pleased with the result. I will say I have absolutely noticed an increase in reliability, and obviously cold starts happen much easier. Considering you are in the Buffalo area, this is a concern for you as well (I went to Buff State by the way). As previously posted, the carbs, if fresh and well tuned, will give very little problems and can be daily driven. But if you are having trouble with the carbs, and keeping them tuned, this is probably an indication of needing a rebuild, or your 40 year old units are just past their prime. You could always get a pair of Ztherapy carbs and call it a day and be driving soon. But if you are considering the swap here are a couple things to think about

 

Things to think about with the swap:

 

The gas tank and fuel system will need to be addressed. Since the 240z gas tank does not have baffles, it should be swapped out for either a 280z tank (must be 75-76 non space saver tank) or a fuel cell (overkill in my opinion for a daily driver/street driven car.)

 

The stock return line will not be sufficient for a fuel injected application. I replaced the stock 3/16'' return line with a 5/16'' hard line. And I am using a Walbro 255 inline fuel pump.

 

and obviously you will require the FI components (intake/afm/engine harness etc...) Google: "Datsun Fuel injection bible" for a complete list of the parts needed, and how they operate.

 

performance wise, I would agree with Six_Shooter, you wont see any real significant changes (unless your current system is not running properly). The biggest difference I have noticed, aside from the easier cold starts is throttle response. This was a HUGE plus for me. I am thrilled with how my system came out and if you want to check it out, I have documented my entire swap from carbs to FI in my build thread (link is in my signature). I too used all NON emissions stuff.

 

Let me know if you have any questions regarding the conversion, I will be glad to help out.

 

Best regards,

 

Andy

 

I just did the opposite swap, 71 SUs on my L28 in my 280Z...it seems to have way better throttle response (even with the stock air cleaner, and even better without the air cleaner) and its definitely quicker...you just need to have the carbs tuned properly for this....car also starts up every time without issues....don't get me wrong, I'm all for EFI...but the stock L EFI sucks, especially for power. Previously I had a cone air filter and all of the emissions stuff removed....it just doesn't compare with the power from the carbs, especially since I can do cams and such with the carbs and make it run properly with it, but the EFI cant compensate. If I went to EFI, I'd go with Z31 Turbo injectors, MAF and ECU....or stand alone.

Edited May 23, 2012 by michaelp

[Pharaohabq]

I'm using GM EFI on my turbo L28, have been for about 4 years.

 

Nice! Could you elaborate on your setup a little, or do you have a thread on it. I've been really interrested in this setup, since the hesco stuff worked so well converting my Jeep inline six.

[Six_Shooter]

Nice! Could you elaborate on your setup a little, or do you have a thread on it. I've been really interrested in this setup, since the hesco stuff worked so well converting my Jeep inline six.

 

I have some detail, though brief, in my build thread, look there and I can answer any specific questions you may have.

[Six_Shooter]

BuffaloZ, Yeah, It's a pain to upgrade to EFI. If you were going to do so, I'd suggest you do the EFI swap to Megasquirt+spark so you can get more efficient control of your injectors/engine. You should get good power, and easier starting, but you won't see a huge difference in power over carbs. You will likely still have some fuel fumes too.

 

Another possibility is going with the Nissan EFI system out of an 86+ 300zx, it uses a MAP sensor and an AFM. it's pretty efficient and has been done on a L28.

 

Something I've really wanted to do is try out the 94 GM EFI system on an L28. Check out HESCO EFI conversion You won't need the full kit, just the harness, you can get a computer cheap on Ebay, and the CPS might work from the Jeep, but if not then There's a guy on here who made a bolt on timing wheel that would work. The advantage is Multi port injection, and the MAP/CPS/O2 sensor automatically tunes the emgine w/o needing an AFM or the bulky datsun flappy afm. The system worked great on my Jeep. But just it's a 4.2L, and I used a ton of junkyard parts, but I'm 100% certain it could be adapted to the L28 since the same GM computer runs both the GM 2.3L and the 4.2L inline 6 cyl engines. you can read about my EFI system on my ProjectJeep site.

 

If you need help, I'd love to help you figure this one out.

 

Phar

 

I looked through Hesco, but could only find ChryCo and Accel EFI being sold there.

 

I looked through your site, and your speculation of the Jeep pattern being adaptable to a GM ECM will not work, at least not with the OBD1 GM EFI. The dizzy ICM (Ignition Control Module) needs to be triggered, by the reluctor, that is located with the dizzy iteself, with even spacing and when each cylinder is at TDC, or rather, when the rotor is pointing at the cap terminal for each cylinder. Where these events happen, in relation to TDC, has more to do with base timing than where the actual TDC is. In other words, if you set the dizzy to 0* advance, then the ICM will be triggered when the cylinder is at TDC, but if you set the base timing to 10* advance, the ICM will be triggered 10* BTDC. This trigger event is only seen directly by the ICM, but the ICM will send what is known as a DRP (Distributer Reference Pulse) to the ECM, so that the ECM knows that the engine is running and at what RPM. These DRPs happen at the same time (or very close to, sometimes there can be some latency), as the trigger from the reluctor in the dizzy that triggers the ICM.

 

When it comes to DIS, the trigger wheel and pattern is different. For some of the GM DIS systems, they use a "7x" wheel (60 degree V6, early I4), that has 6 equally spaced notches, and 1 that is placed 50* before TDC #1 IIRC. This extra notch is known as the "home notch" and lets the DIS ICM know where in the firing order the engine is. Other GM DIS systems, may use a 9x wheel (LT5), or a very complicated wheel with unevenly spaced notches (52 of them IIRC), that based on the spacing and when the two crank position sensors are triggered (Northstar), lets the ICM know where in the firing order the engine is. 3.8L Buick based V6 is different again, regardless of what the tooth pattern is, the ICM sends the same signal to the ECM, "DRP," so that the ECM knows that the engine is running and at what speed. The ICM conditions the trigger signals it gets to send equally timed (basd on steady state RPM) to the ECM. The GM ICM is a pretty complicated device and very neat in what it's abilities are.

[Pharaohabq]

Thanks, Six_Shooter. That's great you're pointing out one possible issue with the Dist. I was thinking an 80's ZX distrib might work, I think it's got the same 7 points that the GM distrib has. If that still won't work, then perhaps I can frankenstein a Datsun and a GM distrib together. On my jeep, I just swapped out the distrib from a 94' for my 87' dist. Worked fine. I doubt the GM and Datsun distribs are interchangeable, but on the top end they might be moddable to make them work. That's a challenge we'd certainly have to overcome. The GM Dist actually has a plate that fits at the top that has the sensor for each. Now really I need to just see what signal the GM distrib puts out, and compare that to the signal from the 83' dist. But yeah that could be a problem, How'd you make yours work?

[Tony D]

I just did the opposite swap, 71 SUs on my L28 in my 280Z...it seems to have way better throttle response (even with the stock air cleaner, and even better without the air cleaner) and its definitely quicker...you just need to have the carbs tuned properly for this....car also starts up every time without issues....don't get me wrong, I'm all for EFI...but the stock L EFI sucks, especially for power. Previously I had a cone air filter and all of the emissions stuff removed....it just doesn't compare with the power from the carbs, especially since I can do cams and such with the carbs and make it run properly with it, but the EFI cant compensate. If I went to EFI, I'd go with Z31 Turbo injectors, MAF and ECU....or stand alone.

 

Funny, on my L28 I took off the headers, triple 40 Webers, etc and restored it all back to stock EFI. Went from 82HP to 147hp at the rear wheels per the dyno. FELT a LOT SLOWER because it didn't make noise and all that, but track times and dyno numbers don't like like the butt-dyno. You will be hard-pressed to beat a properly functioning EFI system. Yes, even the stock one. Yes, even for power. Take a look at the "N/A 200 HP Thread" in the L-Forum and see what it takes to get more power from an L-Engine. $4,000 in heads, cams, carbs, and etc to get 50HP more than what the stock L28EFI produces on a properly-tuned STOCK L28. Curiously I had a CAI and Cone Filter on it initially.... all it did was make noise. I put the stock box back on with a K&N Filter for the 147HP dyno run. (And anybody telling you a stock engine with stock SU's responds better and makes more power without the air cleaner is....uh...."emotionally invested in his work" and has never dynoed the results of that work to see the REAL story!)

 

But I hardly think that qualifies the system as "Sucking, especially for power."

 

It's a simple system, and simple systems have limitations. It's nothing you can't work around. For years people were taking 3.0Liter BMW EFI components and refitting them to their 3.0 L-Engines and they ran flawlessly producing gobs of power. Same goes for the easily prommable GM systems, they have gone on everything from Jeeps to VW's over the years...It just takes knowledge.

 

Today, EFI as a standalone is Cheap. But you still need knowledge. Anybody thinking carb are an 'easy' item to tune I got a few standard instances which will drive you crazy which NOBODY (and that includes some of the top carb gurus in the country on L-Engines) says are solveable. At some point on a carb, there will be things 'you just have to live with'...

 

There IS a reason OEM's went to EFI, you know. It eliminates the 'you have to live with that' syndrome!

[Six_Shooter]

Thanks, Six_Shooter. That's great you're pointing out one possible issue with the Dist. I was thinking an 80's ZX distrib might work, I think it's got the same 7 points that the GM distrib has. If that still won't work, then perhaps I can frankenstein a Datsun and a GM distrib together. On my jeep, I just swapped out the distrib from a 94' for my 87' dist. Worked fine. I doubt the GM and Datsun distribs are interchangeable, but on the top end they might be moddable to make them work. That's a challenge we'd certainly have to overcome. The GM Dist actually has a plate that fits at the top that has the sensor for each. Now really I need to just see what signal the GM distrib puts out, and compare that to the signal from the 83' dist. But yeah that could be a problem, How'd you make yours work?

 

The issue with the trigger pattern I was saying was with the stock Jeep crank trigger pattern, it looks like it has 4 notches in 3 groups, which will not work with a GM ICM.

 

Any of the electronic Datsun Dizzies, except the turbo dizzy should work. I haven't seen any difference in trigger patterns in electronic dizzies. I used a either a '78 280Z or an '81 280ZX dizzy early in my conversion that triggered a GM 8 pin ICM. The only modification I made to the dizzy was locking out the mechanical advance. When I swapped to DIS, I was glad I did, idle smoothed out a lot, and acceleration also got much smoother.

 

Here is a quick video shortly after I swapped in the DIS:

[MadMaxDallas]

You will be hard-pressed to beat a properly functioning EFI system. Yes, even the stock one. Yes, even for power.

 

I don't understand how you say that, when you witnessed a l28 with sus put 190 to the wheels on a dyno.

 

- Whoops, posted on my dads account this is from 78zstyle.

Edited May 26, 2012 by MadMaxDallas

[BluDestiny]

I'm sure he meant stock for stock. Any Z putting out that much is not stock.

[Tony D]

"I don't understand how you say that, when you witnessed a l28 with sus put 190 to the wheels on a dyno."

 

I don't know, maybe because my 0.020" overbore L28 with the head done by the same guy, a cam from the same guy, and EFI makes 278 to the rear wheels?

 

Maybe that might be a reason....

 

Seriously? You are going to debate being able to tailor the engine's response AUTOMATICALLY ON THE FLY? That's not a good thing?

 

Just because something makes XHp doesnt mean it is the penultimate achievement in mixture control. At best, "it works" -- and arguable, with another 20HP further being made with other carbs, the SU's ain't that great.

 

Have I seen 190 on the stock EFI manifold? Hmmmmm, maybe. But you didn't READ my statement. And before you retort further I'd ask that you actually do that before making statement like above again. Read, and understand what is being said before coming up with an off-the-cuff response that is ludicrous. 190 ain't that great! It may be acceptable, but by the owners own actions it has been proven in his application "there IS something BETTER"....and I got news: economics played a role in him NOT using the EFI instead of the Triples he got at a discount.

 

[Tony D]

And I will remind you my BONE STOCK EFI L28 with no cam, with no porting, BONE STOCK makes 147 to the rear wheels.

 

So for about $4000 in head work, cam, carbs and bottom end work you picked up 60hp.

 

Read that again.

 

Read that again.

 

Read that again.

 

That signifies to me that the BONE STOCK EFI does pretty darned good on a BONE STOCK ENGINE. What if I did porting and a cam, where would that EFI go? 190? I know someone with 187 but it's a different dyno and done 20 years ago. Now guys just slap a MS on it and don't look back.

 

In every way, power, emissions, driveability, the Stock EFI was an improvement over the former induction system.

 

If you had problems with it, and didn't take the time to learn the little you need to learn to fix it---that is your problem.

 

 

Don't blame the equipment for the poor performance of the guy behind the wheel!

[78zstyle]

Ah, a wonderful tony d rant where you just start saying random things . Keep it up man, entertaining.

[78zstyle]

Oh. And your l28 (unless its a stroker or turbo) does NOT make 278 to the wheels.

 

Remember we are talking about stock. BONE STOCK. The BONE STOCK efi is worthless for anything but BONE STOCK.

 

So go ahead and spend the next 30 minutes formulating a response laden in non-sequiturs.

[78zstyle]

My inbox is also a better place for your response than you ruining a good thread.

Edited May 27, 2012 by 78zstyle