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Engine Controls for a N/A '77 280z Converted to Turbo?


nienberg.11

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I have the '81 front mount CAS and 'blank' dizzy, for one, which I thought I'd need to change out to use MS,

 

I don't know what Prox spent on his 82-83 type dizzy, but it was easy to install and I would just suggest anyone make that change if they install MSnS.

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Guest bastaad525
I don't know what Prox spent on his 82-83 type dizzy, but it was easy to install and I would just suggest anyone make that change if they install MSnS.

 

cost isn't so much the problem... well not on it's own but yeah it does up the total cost out of what I would be willing to spend any time soon.

 

But as far as the easy install... I dont know if I'd call dropping the oil pump and dizzy shaft easy... and have heard too many stories of problems with getting everything lined back up properly on the install. Never done it myself so I can't say for sure but it sounds like it could be a hassle. Well I guess it'd probably be no harder that the mod Tony did to get his '81 CAS working... so probably is the better way to go.

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  • 6 months later...
Guest crowbar

 

A turbo's fuel requirements are almost independent of rpm! It is a varaible flow engine' date=' so unless you have a non-linear AFM that meters above 3500 when theturbo is kicking in, you can not properly manage the fuel delivery needs of the engine!

 

A RRFPR is basically turning your EFI into a BAD carburettor. For that effort, buy triple solexes, build a surge box, and be prepared for FAR MORE power than you will get using stock N/A electronics on that turbo!

 

In the end, with the advent of the Megasquirt, there really is no reason to screw around with stock electronics whatsoever. The cost of the RRFPR and the time you spend trimming it will not get you the results you will get with the Megasquirt and some basic tuning of the fuel maps.[/quote']

 

Do you know how a stock 300zx turbo ecu works? It just measures the air flow and meters the fuel accordingly.

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Do you know how a stock 300zx turbo ecu works? It just measures the air flow and meters the fuel accordingly.

 

Ummm - yeah, I'm pretty sure Tony knows how the ECU works. :roll: I think that in the text you quoted, though, he was referring to using an N/A EFI setup on a turbo car. So, when the boost hits, the AFM gets pegged almost immediately. If the AFM is pegged, the ECU won't add any more fuel.

 

Also, although Bastaad didn't care for it too much, the quote about the RRFPR being a bad carburetor is pretty much dead on, technically. If you look at the number of things you can tune, at least on a carb you have main and idle air and fuel jets that you can play with (sometimes more, depending on the carb). With the RRFPR, you just have one adjustment for fuel versus MAP, and that's it. In other words, if you were using a carburetor with that amount of adjustability, you'd most likely find yourself wishing you had bought a better carburetor.

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Well guys this thread is pretty old, and now the car is mostly done and running. Bashing fmu's is all well and good; I realize there are better ways to manage fuel for a turbo car. However, it took me very little time, effort, or money to set up, and as TheSkrich testified in my other more recent thread, the car is quite fast at only 7 psi. Since it's running so well, I have no plans to upgrade to MS or any other aftermarket EFI. I need to install my IC and tune w/ windeband, and after that I plan to drive the car and enjoy it. I see no need to fix problems that arent there and waste money as well as time that could be spent having fun with the car.

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Guest bastaad525

actually, depending on what brand and model of RRFPR you go with, there can be a LOT more than just one adjustment to tweak to help you get the a/f ratios you want.

 

The one I bought actually has two seperate adjustment nuts, one controls the rate of gain (how much fuel pressure increase for each psi of boost), the other adjusts the ONSET of gain, which is to say, it adjusts at what point of vacuum/boost amount the RRFPR actually starts to function. In it's stock configuration, the RRFPR can be set to do nothing until 3-5psi of boost is reached, or can be set to come on before boost is even reached (good for use on turbocharged honda's or other speed density type systems that use a MAP sensor instead of a MAF/AFM setup). You can have it adding fuel even at idle around 20 in. hg's of vacuum. It's a pretty wide range of adjustment.

 

There are also less obvious adjustments on the BEGI unit (the one I'm using), you can change out the internal spring, and can also change out this little plate/washer that affects the overall spring rate in a different way that can actually change the onset of gain even more dramatically, increasing the boost threshold that must be reached before the RRFPR starts adding fuel pressure.

 

Yes it the end it is a very simple device and can't hold a candle to something like Megasquirt or SDS, but it still has quite a range of adjustments and can be tweaked for a wide range of applications and fuel needs.

 

There are other brands and models out there that offer even more adjustments, I forget the brand but I think it was a Vortech? that had something like five different adjustment screws on it and I've heard very good things about that unit and how tweakable it is and how easy it is to set up for exactly the fuel curve you want in varying driving conditions.

 

Really when it comes down to it the stock 280zxt EFI is pretty simple itself, relying on relatively few inputs to determine optimal AFR, and really gets maxed out quickly once you start upping the boost, most people agree that past 9-10psi it just cant compensate and will run lean. The RRFPR is a perfect way to add more fuel ONLY WHERE YOU NEED IT, at boost levels higher than the stock EFI can provide a safe AFR.

 

There have also been tests done, I forget which magazine right now but they had a great article on it (I want to say Hot Rod magazine?), where they showed how raising the fuel pressure actually had great side benefits, including a much more even and much better atomized fuel spray. They found that at around 70-80psi the injectors achieved their optimal spray patterns. The article had a LARGE pile of pics backing up what they were saying, also with a ton of math for helping you figure out how much fuel pressure can support how much increase in power.

 

People do love to knock the RRFPR's, mostly people who've never tried one, but there are a few guys on here including myself who have used them to very good results and love them. Sure some actually come close to the cost of a barebones megasquirt setup but in terms of ease of install and tuning the RRFPR holds the upper hand... don't need to rewire your whole EFI, just find a place to bolt it up and route your fuel return line thru it, hit the dyno and start turning a couple screws til you get the a/f you want... that simple.

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actually' date=' depending on what brand and model of RRFPR you go with, there can be a LOT more than just one adjustment to tweak to help you get the a/f ratios you want.

 

The one I bought actually has two seperate adjustment nuts, one controls the rate of gain (how much fuel pressure increase for each psi of boost), the other adjusts the ONSET of gain, which is to say, it adjusts at what point of vacuum/boost amount the RRFPR actually starts to function. In it's stock configuration, the RRFPR can be set to do nothing until 3-5psi of boost is reached, or can be set to come on before boost is even reached (good for use on turbocharged honda's or other speed density type systems that use a MAP sensor instead of a MAF/AFM setup). You can have it adding fuel even at idle around 20 in. hg's of vacuum. It's a pretty wide range of adjustment.

 

There are also less obvious adjustments on the BEGI unit (the one I'm using), you can change out the internal spring, and can also change out this little plate/washer that affects the overall spring rate in a different way that can actually change the onset of gain even more dramatically, increasing the boost threshold that must be reached before the RRFPR starts adding fuel pressure.

 

Yes it the end it is a very simple device and can't hold a candle to something like Megasquirt or SDS, but it still has quite a range of adjustments and can be tweaked for a wide range of applications and fuel needs.

 

There are other brands and models out there that offer even more adjustments, I forget the brand but I think it was a Vortech? that had something like five different adjustment screws on it and I've heard very good things about that unit and how tweakable it is and how easy it is to set up for exactly the fuel curve you want in varying driving conditions.

 

Really when it comes down to it the stock 280zxt EFI is pretty simple itself, relying on relatively few inputs to determine optimal AFR, and really gets maxed out quickly once you start upping the boost, most people agree that past 9-10psi it just cant compensate and will run lean. The RRFPR is a perfect way to add more fuel ONLY WHERE YOU NEED IT, at boost levels higher than the stock EFI can provide a safe AFR.

 

There have also been tests done, I forget which magazine right now but they had a great article on it (I want to say Hot Rod magazine?), where they showed how raising the fuel pressure actually had great side benefits, including a much more even and much better atomized fuel spray. They found that at around 70-80psi the injectors achieved their optimal spray patterns. The article had a LARGE pile of pics backing up what they were saying, also with a ton of math for helping you figure out how much fuel pressure can support how much increase in power.

 

People do love to knock the RRFPR's, mostly people who've never tried one, but there are a few guys on here including myself who have used them to very good results and love them. Sure some actually come close to the cost of a barebones megasquirt setup but in terms of ease of install and tuning the RRFPR holds the upper hand... don't need to rewire your whole EFI, just find a place to bolt it up and route your fuel return line thru it, hit the dyno and start turning a couple screws til you get the a/f you want... that simple.[/quote']

....i see the RRFPR on Ebay for cheap and will probably try one out on my remote turbo 1988 200sx SE...i like the idea of keeping my stock ecu/injectors because it runs great on them.... i havent been able to find a reasonable price on a turbo 300zx ecu and matching injectors,so this RRFPR should get me close to those using the non turbo parts.

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Guest bastaad525

*shrug* I think I spent $200 from mine or maybe $250 straight from BEGI. But yeah I wouldn't be surprised if you could pick them up much cheaper on Ebay.

 

They are just soooo easy to install and tune, which is why I decided to go with one instead of going with bigger injectors. I love that this thing doesn't affect off boost driveability or fuel mixture at all.

 

I'll never say they are the best way to go but it works and works well enough for me.

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  • 3 weeks later...
Guest charles_richey

This is my first venture onto a forum. Its also the first time I've ventured into z's. This Friday I'm picking up a 1979 280ZX. I wanted to get a 280Z but I'm getting this one for $350 dollars and the engine was rebuilt about 20k ago. There are alot of questions I have and you guys seem very knowledgable. First the car has an automatic, how hard would it be to switch this to a manual. Would you recommend a 4 or 5spd if going to a manual. How hard would it be to turbo? You've been talking about turboing 280Z's I just wanted to find out if you know about turboing a 280ZX. What mods would you guys suggest to get the most bang for the buck. What kind of power did these cars make stock (hp/torque)? Is there a dual exhaust out there that sounds good but not too overwhelming inside the car? Any info you guys have to offer would be great?

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Guest bastaad525

whoa... that's a lot of questions dude :icon44:

 

I'll say it to you first because if I don't someone will... as a new member of the forums it's like your initiation rite... use the search feature. Not that we mind answering questions (well, most of us, anyways), but there is soooooo much accumalated knowledge built up in the archived threads on this board that you can usually answer any question you have and then learn the answers to 10,000 more questions you haven't even thought to ask yet in just one good long sitting of searching and reading. This forums been around for ages and so many people here have explored so many different aspects of the possibilities of the Z and ZX cars and documented them here that you are 99% likely to find someone who has done what you are thinking of doing and has already posted the info you are looking for.

 

Even if you have some specific question and you don't want to go looking for the answer right that moment (hey guys face it sometimes it can be very time consuming digging up some of these answers with the search), I still recommend setting aside an evening sometime and going thru the archives anyways even if you don't have a specific question just becuase there is really so much good info... you'll probably be amazed all you can find.

 

Then, when you do come to post your specific questions, a couple basic guidlines for you... one, it's a good thing to just start your own thread, and two, try not to ask so many all at once. Start off with a few and when the answers start coming go from there. Ask 20 questions all at once like that and you're more likely to just get 10 replies of "use the search" :-D

 

My quick answer for you though... switching to a manual isn't that hard, go for the 5 speed, adding a turbocharger to any nonturbocharged car is never 'easy', in the case of any Z it's always easier to either start with a turbocharged model or find a turbo 'donor car' that you can grab the whole engine and all electronic related stuff.

 

You're just starting out so slow down a bit, get the car, drive it, learn a bit about it, read read read and then... read some more, ask questions here questions there, see what's out there. Rush headlong into it and you're gonna hit a wall hard and knock yourself out. :-D

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  • 4 weeks later...
Guest crowbar

The 300zx 84-89 ecu DOES have a MAF that can meter above 3500 rpm. Its output IS a non-linear exponential type output.The 300zx NA ecu DOES use an adaptive control scheme. In other words, it looks at mass air flow and rpm and gear and makes a 'load' computation that can be described as an electronic boost calculation.The statement that the MAF gets pegged as soon as boost hits is false. Perhaps for a flap door AFM but not a MAF hot wire technology.

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  • 3 weeks later...

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