'82 ZXT ECCS A/F curve + Nitrous at low rpm = perfect match?

[Guest bastaad525]

Spending way too much time looking at my dyno sheets

 

well... been thinking of ways to make use of the super rich mid range that seems to be programmed into the ZXT ECCS. Looking at my dyno sheets, or those of a few other guys I've seen, running stock '82-83 ECCS, there is a definately pattern of the fuel curve going WAY rich when boost first hits and staying that way up until about 4000rpm. From 2400 to 4100 rpm the air/fuel ratio stays richer than 12:1, and is curved, dipping as low as 10:1 at about 3500rpm. I've been wondering if this is rich enough to support a small shot of nitrous, 25 or 50hp shot at the max, without any additional fuel. I'm thinking of possibly setting it up to only kick in as soon as going WOT, and only to spray up to 4000rpm, as a way to improve off boost and low rpm response, to help with getting out of the hole, and improve cruising throttle to WOT transition response. Dont know much about naaaaaaaawwwws but I'm thinking this would be more than enough fuel to support such a small shot safely... would the internals of the motor be able to deal with both nitrous and boost though? I could always have the nitrous cut off even sooner, even as low as 3000rpm... just get the car into full boost quickly. Imagine how long a full bottle would last if used like this!

 

As an alternate idea are there any boost controllers that can create a boost 'curve'? Set it up to run higher boost, maybe 13psi, up until 4000rpm then drop back down to 9-10psi. I do like the Nitrous idea better, if only because I really want help getting out of the hole faster (still not doing so hot at mastering the art of launching a turbo) and coming up on boost as quickly as possible.

 

Any one with any ideas, throw'em out here! I know some of you guys will probably say I should instead be finding a way (megasquirt yada yada) to flatten out the fuel curve, but I'm thinking... I've got all this extra fuel, instead of trying to get rid of it, better to find a good, safe way to use it to get more power!

 

My only other question is this: I know the Nitrous kits I've seen (either 'wet' or 'dry' setups) all come with various ways of supplying more fuel along with the nitrous, but I'm thinking... shouldn't a kit that does NOT come with any method for supplying more fuel cost less? Are any nitrous kits sold like this? All I would need are the bottle, lines, solenoid, jet, and trigger switch right?

[Guest bastaad525]

wow, no one with any input on this?

[Lockjaw]

Are you talking dry nos? If so, I think your idea is crazy.

 

I can give you some insight on the richness. The ecu swtiches over, depending on airflow, to batch fire at like 90% duty cycle, from 40 to 45% at about that RPM. Usually you can feel the difference if have a stock turbo, and are running 10+psi of boost, about 3500 to 3800 rpms, the switchover occurs.

 

I had it very pronounced on my JWT box, since I was one of the first people to run the Cobra MAF set-up and they have tuned it out for me. I am going to be going to a dry NOS controller, JWT is going to put the computer control device in my ecu for me, and it will give me and extra 65hp.

 

If you ask me, you are asking for trouble. Spend the money and convert to a JWT or Z31 setup.

[Guest bastaad525]

How hard to switch to the JWT ECU? How much of a difference does it make over the stock ECU? What else get's changed besides the ECU itself?

 

 

I appreciate the input Lockjaw though I'm not quite sure how your info about the batch firing applies to running NOS Not saying that in a disargreeable/argumentative way, I just totally did not understand it. So all the extra fuel between 2500-4000rpm wouldn't be enough for a small 25hp shot of nitrous I take it?

[Guest Zcarsmakemyheadhurt]

I see where your coming from with your idea bastaad. If you have a wide band to watch over things I would try a NOS system using a single fogger tip from a dry system and no regulator set up that comes with a dry kit. Use small jets (not that jetted for a system) because NOS rates jetting with a fuel jet. Not using a fuel jet may do something kinda crazy so keep a small jet till you know what is what, you may see that lean situation go away quick. I think I would probaly go larger on the turbo or turn up the boost some more to lean it out. good luck.

[Sean73]

It might work, but I disagree with it in principle. Correcting a bad a/f curve with nitrous is just not good science. Fix the problem with your fuel system, then do the mods for high HP. You might have a leaky injector, bad sensors, bad AFM, incorrect wiring, etc.. etc..

[SleeperZ]

I think I would probaly go larger on the turbo or turn up the boost some more to lean it out. good luck.

 

Alex, your advice is going to cost someone their engine. I am not going to explain (once again) how the Z fuel injection works by measuring the airflow. Unless you can gain an understanding of Nissan EFI, please refrain from these sorts of uninformed comments.

[Guest bastaad525]

It might work, but I disagree with it in principle. Correcting a bad a/f curve with nitrous is just not good science. Fix the problem with your fuel system, then do the mods for high HP. You might have a leaky injector, bad sensors, bad AFM, incorrect wiring, etc.. etc..

 

 

but that's the thing, it's not a 'bad a/f curve', this is how they ARE from the factory. I have seen now, FOUR other stock '81-83 turbo motors with stock EFI dynoed, and ALL of them ran super rich somewhere between 2500 and 4000rpm. And I have gone over much of the EFI system trying to trouble shoot other little gremlins and taken care of most if not all of the problems there.

 

Alex... while my first inclination might have been just to turn up the boost, problems are that a) I have no I/C installed yet so I'm pushing it with 9-10psi as it is, and I'm ONLY running rich from 2400-4000rpm, after about 5000rpm it starts to head to the lean side at about 13:1 air/fuel ratio... too lean for a turbo application, definately too lean for a non intercooled turbo application, and too lean to even imagine turning up the boost any more than I already have

 

 

This is why I'm SPECIFICALLY looking for something ONLY to take advantage of the factory programmed super rich midrange, something that will just help get going faster from a standstill or help me get up on boost faster when I'm just cruising and suddenly floor the throttle... especially on the freeway, 4th or 5th gear, it can take a little bit for the turbo to spool up, so thinking of ways to take advantage of the extra fuel that comes on at that point to help get the car scootin a little faster.

[SleeperZ]

Just because it has fueling issues "from the factory" doesn't mean it's a reliable platform for selectively targeting a nitrous system. Personally I would not mess with nitrous unless I had the full range of safeguards in place. Bastaad, did you read what James (240Z twin turbo) did with his nitrous? He is one of the most experienced around with nitrous, and he flamed his intake pretty good.

 

Seriously, don't tailor a nitrous sytem to take advantage of a poorly performing fuel computer, 'cause that's what it will do. BOOM!

[Lockjaw]

How hard to switch to the JWT ECU? How much of a difference does it make over the stock ECU? What else get's changed besides the ECU itself?

 

 

I appreciate the input Lockjaw though I'm not quite sure how your info about the batch firing applies to running NOS Not saying that in a disargreeable/argumentative way' date=' I just totally did not understand it. So all the extra fuel between 2500-4000rpm wouldn't be enough for a small 25hp shot of nitrous I take it?[/quote']

 

batch fire means all the injectors are firing at the same time, in this case all 6. Some of the newer boxes are sequential, and fire in batch fire mode, 3 at a time. Most of the aftermarket efi's are fully sequential on each injector, which is the best way to go.

 

If you are having richness issues there is another option. On the AFM, on the plastic cover side, there is a little round plug. Drill a small hole in it, and pull it out. You now should have access to a screw, which is an air bypass inside the AFM. You can also see it by looking down inside the afm. Make sure you know where it is, and then back the screw out some, which will let UNMETERED air thru the system, and should make adjusting your fuel curve a little bit, easier.

 

By the way, my JWT box is quasi sequential, it fires in 3 cylinder batch fire mode up to 49% of capacity, and then switches over to full all 6 batch fire above that. Probably why I get 20 mpg driving how I drive.

 

 

Oh I probably did not explain it to well, a batch fire efi fires all the injectors at the same time, so in your case, you get all 6 firing, even though spark is on one cylinder. Thats because the box only has one timer, it would have to have 6 to be sequential, which would fire the injector on the firing cylinder only.

 

Anyway, thats my story, and I am sticking to it.

 

8)

[Guest bastaad525]

okay... wont do it then

 

and yeah, I do plan on messing with the AFM next time I go to the dyno and seeing if I can't tune out this rich midrange w/o screwing anything else up.

[Guest Zcarsmakemyheadhurt]

Sleeper are you serious? Just because I prefer higher horsepower that I can tune safe doesn't mean I haven't busted my head making power on a stock ECM. I've done all the tricks, the best I have seen is 11.49 @ 119mph, N/A ECM, stock turbo, turbo injectors and a converted turbo AFM. Do better then talk your shit about me.

 

Alex C

[SleeperZ]

Sleeper are you serious? Just because I prefer higher horsepower that I can tune safe doesn't mean I haven't busted my head making power on a stock ECM. I've done all the tricks' date=' the best I have seen is 11.49 @ 119mph, N/A ECM, stock turbo, turbo injectors and a converted turbo AFM. Do better then talk your dodo about me.

 

Alex C[/quote']

 

I am dead serious Alex, and normally I am quite mellow about this. But when you keep making comments like you know what's going on, but obviously don't, it can be misleading to someone who is needing correct information. Just because you have built a fast car doesn't mean you know "dodo" about a Nissan ECCS.

 

You want to discuss this further? P.M. me, I don't think we should hijack the thread any longer.

[Lockjaw]

Fix the problem, don't band aid it. Turning up the boost in theory is a good idea, but ultimately, unless the boost drops with RPMS, he is going to run lean and pop the engine.

 

NOS with no controller is just plain nuts. If you have an issue, you can blow chunks out of intercoolers, plenums, and perhaps trash your turbo.

 

Fix the problem, then do power adders.

 

I would convert to Z31 EFI, do a JWT, or standalone.

[Lockjaw]

Sleeper are you serious? Just because I prefer higher horsepower that I can tune safe doesn't mean I haven't busted my head making power on a stock ECM. I've done all the tricks' date=' the best I have seen is 11.49 @ 119mph, N/A ECM, stock turbo, turbo injectors and a converted turbo AFM. Do better then talk your dodo about me.

 

Alex C[/quote']

 

Don't forget the NOS.

[fl327]

Sleeper are you serious? Just because I prefer higher horsepower that I can tune safe doesn't mean I haven't busted my head making power on a stock ECM. I've done all the tricks' date=' the best I have seen is 11.49 @ 119mph, N/A ECM, stock turbo, turbo injectors and a converted turbo AFM. Do better then talk your dodo about me.

 

Alex C[/quote']

 

Don't forget the NOS.

 

And no intercooler right?

[Guest bastaad525]

yikes... seems like every 3rd question I ask get's someone arguing. Sorry guys. Well anyways it was just an idea. Again, I didn't consider the super rich mid range a 'defect' with the ECU's fuel curve because it seems ALL '81-'83's do it. I keep bouncing back and forth considering what might be a good, reasonably priced alternative... Z31... JWT... Megasquirt... but truth is NONE of them are reasonably priced, not for me, not right now. Even a reasonably priced nitrous system is outta my price range really, but looking at the fuel curve the idea occured to me so I just wanted to see if it was feasible. But for the time being, I'm stuck with what I got. But for all the times people have suggested to me to swap out the stock EFI.... I've seen enough people make good power on the stock ECU, a good bit more than what I'm making now, so I know it can be done, safely and reliably. I'm in no rush to get rid of it until I've hit it's limits and only if that limit proves not to be fast enough.

 

Lockjaw hit on my other idea, which was a way to have higher boost in the midrange and then have the boost taper off after the fuel ratio leans out... are there any boost controllers than can taper boost off with rpm? Anyways... I am going to try to fix the curve. I'll be ordering an adj. FPR soon. I'm going to turn the pressure up to get my high rpm a/f down to around 12:1, then I'll adjust the AFM spring to try to lean out the midrange and compensate for richening with the FPR. I'm thinking I may just be able to get a relatively flat curve and still have the car idle and run decently off boost... though I do worry a little as I've been playing with the AFM the last week or two and man the car is SUPER sensitive to adjusting it. Any more than 3 gear teeth tighter or looser on the gear and the idle goes to hell. I've tightened/leaned it 3 teeth from the stock setting... am VERY curious to see how this effected the super rich mid range, but I'm waiting to dyno again until after I get that FPR. Alternately, I may get those ford injectors people keep lucking out on at the junkyards, instead of upping the fuel pressure.

[Lockjaw]

Why don't you hunt around and get a 300ZXT harness, ecu, dizzy, MAF and injectors and wire that up? It would not be to expensive, probably about what your AFPR costs. There are people on the board who can guide you thru the process.

 

 

You will spend more time, effort, and money fooling around trying to bandaide this thing, and you would just be better off to save a little money, and spend it wisely.

 

It always costs more to "redo" something. Do it right the first time, you will be glad you did.

[SleeperZ]

I agree the Z31 would be overall a better solution, but you may get good results just using an MSD FPR and AFM adjustments. For the price, you may get good results. Good luck with what you decide to do.

 

And, BTW, I only start arguing when my spider "BS" sense starts tingling.

[Guest bastaad525]

don't think I can pick up a Z31 setup for as cheap as an AFPR... MSD AFPR runs $55

 

Considering there are more than a few guys getting good results with bigger injectors and AFM tweaking... and I know higher fuel pressure isn't going to be the same as running bigger injectors but it will be close... and considering I'm still limited to 10psi by the fact that I dont have an I/C, and will be for some time, I think the adj. FPR will probably work fine for me, for now. After I get an I/C installed and start cranking the boost then I'll probably want and need to start looking at other options, and I will most likely go with the Z31 only because it seems less likely that I can screw that up.