370cc's for me??? QUESTIONS re: 370's and stock ZXT EFI

[Guest bastaad525]

I just KNOW Tim240z will have something to say about this

 

 

After all this time that I've been sticking to my guns, swearing up and down that I was not going to upgrade to 370's, that I didn't need or want them. Well... then someone just happened along and offered me a set for cheaper than dirt cheap, and skewed my perspective a bit .

 

So, I'm very seriously considering the upgrade now. And though I still think they might be overkill, as the chances that I'll be upgrading from the stock turbo any time soon (read: within the next couple years) are slim to none... so even if I do swap to 370's, I'm still gonna be limited by what that little T3 can put out w/o overtaxxing it. A limit I"m already very close to breaking as it is.

 

Anyways... to the questions!

 

For everyone who has run 370's on stock EFI (talking '81-83 EFI), and just adjusted the AFM to compensate.... how IS the off boost, every day normal driveability with this setup? Be HONEST... I want to know exactly how the car will behave modded like this. I have a hard time believing off boost driveability is perfectly fine and bug free running this setup. How about idle? How do the plugs look? Remember I'm running the BEGI FMU right now, which is providing enough fuel for what I"m running, while not affecting off boost driveability at ALL. I know I was warned about this... if I go 370's I'll probably ditch the FMU.

 

Is there any, CHEAP alternative to compensating for the over rich off boost fuel curve? Say, just lowering base fuel pressure a bit? Piggyback or for that matter, fully programmable EFI is OUT OF THE QUESTION for right now so please don't suggest any of that!

 

For anyone who has dynoed running 370's on stock EFI, what did the A/F ratio look like? Stock '81-83 EFI ALWAYS seems to follow a given pattern, that it will run super rich at the onset of boost, up to about 4000-4500rpm, where it will lean out quite a bit, and then at 5000 or 5500rpm, will lean out some more and continue leaning out up to redline. When I added the FMU, the fuel curve actually didn't change at all, oddly... it just richened up the whole thing, but the SHAPE of the curve was exactly the same. I expect the same will happen with the 370's???

 

I'm hoping to get some fast answers to this one... I know the weekend is the WORST time to ask anything around here but I just got paid and am being offered first dibs on these injector, and don't want to keep the guy waiting or miss out on my opportunity.

[ToplessZ]

Hey bast something else to rethink might be a good aic you can get the hks aic on ebay for around 200 bucks. I think its like 600 new but I see them on ebay all the time and they have alot of adjustability. Upgrading that stock turbo would be recommended and if your not looking for a huge turbo capable of 35+psi boost there are some less expensive options out there including upgrading using your turbo with the t4 conversion kit. I know there were a few guys on here running the 370's hopefully they will chime in here.

[Guest bastaad525]

I keep saying it but guys just don't want to believe me here... AIC's and AFC's and Piggyback this and stand-alone that... for right now it's all just out of the question. Same deal with an upgraded turbo. I've put a LOT of money into this turbo swap, more than I had originally planned, by far, due to mishaps in part. Being married, and both me and my wife working, she has as much say on every $$$ that get's spent as I do. And truth be told she has held off on or sacrificed a lot to let me spend the money I have on this car. This is why my goals were always modest... whatever I could reach on stock injectors and turbo with just a few upgrades. The last few things I need to do on the car and will do soon are safety or maintenance oriented... I'm pretty much done with performance oriented upgrades for a lonnnng time. The ONLY reason I'm even considering buying the 370's now is because of the great great price. But if I get them I will need to be able to make them work without any further mods or trips to the dyno. And without buying more hardware.

[Clifton]

370's are still too small. If you put a decent turbo on there and run 18 psi you will be beyond what they can support. I would run 450's minimum. preferably 550s. You could keep your stock 260cc's and run 2 550cc + injectors with an AIC and that would come out out about 450cc per cylinder. That's what I origainally ran and got 368rwhp @ 15 psi. Plus you have total control over your fuel under boost. If you are going to go bigger atleast go large enough so you don't have to upgrade again when you crank the psi up a little more. I'm running 6 440's and 2 450's(AIC) on my 7MGTE. With the right turbo you will need the extra fuel.

[Cody 82 ZXT]

You really ought to think about upgrading that turbo. I know you've said it a million times but, really at this rate I give you under a year (6 months) before your asking about big turbos. Theres nothing wrong with that it's just a move in the right direction.

 

I never used the 370's but, I know Len did and liked them. You might look him up and PM him and ask about how he made them work.

[Guest ON3GO]

i know you just said this bast.. but i think the stock ecu is the only down side to your car.

i think you could have a 100% reliable, fast, and smooth turbo Z with a nice standalone unit.

get it tuned right and then let it be...

you can find some nice used haltec units for real cheap and the car will drive 100% better then with the stock stuff.

 

if you dont wanna do this then get the 370cc injectors, it wil run abit richer off boost but they will deff help when you wanna up the boost some.

it cant be worse then my 77ecu/harness L28ET car off boost, and mine runs awesome off boost.

only when the motor is cold will it surge abit off boost, but thats it.

mine does run rich though but the AFM is tuned for bigger injectors.

 

mike

[fl327]

I wish I would have taken my own favorite advice and just swapped the turbo out. 370cc is good upgrade I think, theres a set on zcar.com going for a good price.

[Garrett76Zt]

Hey Bast,

First off 226 hp is not near the limit of the stock turbo. I would say 275-300 would be. At any rate I would say that if you arent going to raise boost then dont bother with 370's if you are then do it. Furthermore if you do get the 370's don't get rid of your FMU you will only need to play with the fuel curve more.

 

I run 370's at 15psi on stock ecu and a regular FPR. With this setup I can only move the stock map richer or leaner. That means the whole map moves up or down (on a A/F chart) I have to run 45 psi base pressure to make it somewhat safe on the topend, actually still on the lean side. So you will need to run stock fuel pressure and adjust the rate of rise so that it stays safe on the top. That way you should still be able to get some good gas mileage. But the power level was dramatically different when I did 370's. The topend was way stronger. and my 1/4 mile times dropped by nearly a full second. 13.4 down to a 12.7 only other change was little more fuel pressure and about 2psi boost.

[Guest bastaad525]

Huh... not quite the responses I was expecting.

 

 

Well I'm just gonna say it again... I am just about OUT of MONEY here, so upgraded turbo's and standalone EFI's are out of the question! Do I WANT a a T3/04? SURE I do! But that's $400-700 I just don't have the option of spending. And to be honest it's more than money keeping me away from the programmable EFI... I don't want the headaches of trying to get it tuned right. But it doesn't matter, I can't go spending any more big money on this car for a while, period. And when I do have another few hundred I can spend exhaust is next thing on my list anyways, and then I NEED new bushings.

 

And anyways, I don't ever go to the track, and probably never will... as it stands, making the car much faster is almost a waste. I'm finding that at the level it's at now I really don't ever even get to utilize the power that it has... blasting up freeway onramps, and that's about it. Traction is also JUST starting to become a problem, and I dont' really want to exceed that limit because then the car stops being fun and starts being dangerous. Even with upgraded suspension I"m afraid to push the thing in turns because it's just so easy to overpower the tires now. I originally wanted this car to be a great mountain road car but now I feel it's almost just a drag car that will never get dragged! At this point I'm thinking another upgrade I should get soon is an in-car boost controller so I can turn the boost DOWN when I feel like hitting the hills! But anyways that's a whole other subject.

 

I do like the AIC idea, simply because I can set it up the same way as the FMU, that is, to only come on at a certain point, and tuning for that should be a breeze. But... theres that issue with $$$ again....

 

Well thanks guys now I"m even more confused

 

Any other 370 users can chime in here? Really this topic kinda got off topic anyways... I'm not so much asking if I SHOULD get 370's, but rather, how is the car going to run with them installed, during normal driving, and idling, and really just how effective is adjusting the AFM once they are in?

[lifegrddude]

I'm using the 370's with the stock efi and stock fpr. When I dynoed the motor last year with the stock turbo and 9 psi, I was running an a/f ratio between 10-11, and on the second pull it hit a high of 12.7 at the top. (6000 revs) I have since upgraded the turbo and just recently got an intercooler installed, but I haven't had time to dyno the setup yet. With the 370's, it's a bit rich at idle, but there aren't any ill effects. Nothing out of the ordinary during cruising either. The highest I have run my setup on 91 octane gas is about 12 psi with no pinging or odd readings from the narrowband a/f gauge. Before the intercooler, I could only run about 10 psi without pinging or bad readings.

 

John 82ZXT

[ToplessZ]

Bast. If you ever get to the point where you need the aic units will have only become more reasonable. I just saw a blitz unit for 80 bucks on the bay. Very simple to hook up and adjust. Just for future reference. I would just enjoy the car with the condition you can afford. When the right time comes and you can afford it. Then buy the next upgrade. There is never a rush when you are at the point with the car that you are. Besides you should always have a little cash set aside for maintenence and small fixes when they occur. If you have spent that money on upgrades then you have down time. Just a thought.

[Guest bastaad525]

I would just enjoy the car with the condition you can afford. When the right time comes and you can afford it. Then buy the next upgrade. There is never a rush when you are at the point with the car that you are.

 

 

That's what I'm doing! I'm not in this big rush to upgrade upgrade upgrade... the car is already very quick for a street driven car, maybe not the fastest at the dragstrip, but 230rwhp in a 2400lb car definately does not feel slow to me. Yeah just like most everyone here there's always that part of me that wants a 400rwhp beast that can roast tires at will in four out of five gears and run 11's all day long, but that's just not practical for me. And again, on SoCal's clogged streets and freeways, really... other than a dragstrip, when could I actually put that power to use?

 

Besides you should always have a little cash set aside for maintenence and small fixes when they occur. If you have spent that money on upgrades then you have down time. Just a thought.

 

Yeah well... I"m very bad at saving money, at least, I have been since I started this Z project. However, after much advice from Hybrid Z'ers I did go out and find myself a small, cheap, econimical yet still very fun to drive Sentra SE-R to use as my daily driver and backup car for whenever the Z is out of commision. Funny thing is the Z was having all kinds of problems before and now that I have another car suddenly the Z is driving pretty much problem free??? So I still drive the Z more than the Sentra, which my wife get's angry about

 

But that's another reason why I'm TRYING, very hard, to just say "The Z is DONE for now!!" so I will stop spending money on it and start saving as quickly as possible, as me and my wife are desperate to move and want to buy a house by this time next year. And that just isn't ever gonna happen if I keep prioritizing this car.

 

 

lifegrddude - Very very interesting info bro!!! And very confusing info as well! You are the first I've seen mention dynoing on stock EFI with 370's. I'm actually more confused now... your fuel curve doesn't sound a whole lot different from mine when I first dynoed, w/o an I/C, at 10psi on the stock turbo, and I was running stock injectors at the time! I was just a tad leaner, but the extra psi could easily account for that. Frankly I'm baffled, with the 370's you should have been nice and rich (more like nice and PIG rich!) all the way to redline at 9psi of non intercooled boost on the stock turbo.

 

Case in point, I"m still running the stock injectors with the rising rate fuel pressure regulator set to max out at 65psi of fuel pressure, 12psi increase over what the stock FPR would provide at WOT/full boost. At 12-13psi of boost from the stock turbo, running an I/C, my fuel curve is now EXACTLY as you describe yours! Averages between 10-11, and hits a lean peak of 12.7:1 right before 6000rpm... I mean it is exact! But I find it VERY hard to imagine that a mere 12psi increase in fuel pressure has my injectors flowing 110cc's more, or for that matter, my injectors would have to be OUTPERFORMING your 370'ss considering I'm running more boost and the I/C!!! The math doesn't back that up either... using equations provided at RC Engineerings website, to solve for flow increase from increased pressure, my injectors should flowing about 295cc's. So how is it that (effectively) 295cc injectors are giving me the same fuel curve at 12-13 psi of intercooled boost as your 370's give you at 9psi non intercooled?

 

You SURE you got 370's???? I mean... it sounds like a stupid question... but what you're saying definately 'fits' better if you were still running stock 260's. Or maybe there is some other problem in your fuel system??? Pump maybe???

 

Garrett76Zt - your results baffle me as well... you're saying that at 15psi on the stock turbo, and 370cc injectors you still ran a bit lean on the top end? So I would need to keep my FMU to still provide the extra fuel pressure I would need to keep rich and safe on top? This is all very interesting info... so the 370's themselves are not the end-all-be-all answer I once thought they were, and can still be outpaced by the stock turbo eh? Wow... I thought the 370's would be more than enough for the T3.

 

I dunno if I want to turn the boost up much more... I had heard so many times that anything over 15psi measured AT THE COMPRESSOR, was way out of the efficiency range of the turbo, and was also spinning it way fast and most likely shortening it's life dramatically. Add to that, the fact that I'm getting about 1.5psi of pressure drop accros my I/C, and I'm gunshy of exceeding 14psi in the manifold. I know guys do it all the time here... BUT, I also have to keep in mind that the turbo itself is the last major component that came out of my donor car that I have NOT had to rebuild yet, the head and then piston rings failing within months of the swap at STOCK boost levels... I'm amazed the turbo is still going, to be honest, and am scared to push it. And I already know for a fact that the BEGI FMU can cover me at that level of boost. GRAAAARRRR I'm such a dumbass why didn't I just set it at 14psi when I was at the dyno, tune at that and be done with it!!

 

 

Still getting more and more confused here LOL

[Garrett76Zt]

Bast, Yes even with raised Fuel pressure and 370's it runs a little lean on top. Really its because I can't do anything but richen or lean out the entire map. At any rate you have to remember that at 15 psi thats more than double the original amount of boost this setup was inteded to see from the factory. I think 370's are plenty as long as you can dial them in. you have that abilitity with the FMU. This is the cheap way to make more power, but it sounds like you aren't even sure if thats what you want. So I don't know what to tell you.

[Tim240z]

I can hear the thunder of a rolling snowball

[Cody 82 ZXT]

I can hear the thunder of a rolling snowball

 

 

It seems it always starts the same:

 

Just a few mods for this reason or that and then next thing you know it's Viper fryer.

[Guest bastaad525]

I can hear the thunder of a rolling snowball

 

 

ROFL what took you so long???

 

I just KNOW Tim240z will have something to say about this

 

 

 

 

Garret76Zt - heh well... make no mistake... who DOESN'T want more power??? Well okay just a little... I mean if I had endless $$$ I'd definatley have Z capable of taking out just about any car in any straight line, road coarse, rally, swimming event, you name it! For now it's just all about reliable power on a budget... but I'm still a bit confused as to exactly how far I can reliably push some of these components??? Like the stock T3?? I thought 15psi was it? As far as needing the 370's to make more power.... I'm actually not TOO far off from your numbers with the stockers... If I added the 60mm TB and 3" mandrel exhaust (running crappy 2.5" pressbent now) and upped the boost to 15psi (vs. 12psi when I dynoed) I think I'd be right there with you on the stockers, but running like 80psi of fuel pressure (that same question again, how far can I push and stay reliable?). So... it's not so much that I need them for more power, it's more like I just want them for added safety, so I don't need to strain my fuel system with such high pressure.

[cygnusx1]

Hehe

so I don't need to strain my fuel system with such high pressure.

 

Poor fuel system (playing smallest violin)? What about the poor engine, chassis, trans, driveshafts, rear end, and wallet? All of which are working harder than the fuel pump at 80psi.

 

I guess bigger injectors would work but, at least in my case, I can choke the motor with fuel at 13-14psi boost with the BEGI if I wanted to. However, it still it drives like factory off boost.

 

I am done modifying my Z until next year or two when I go out looking for a programmable ECU, injectors, pistons, rings, headgasket, rod bolts, head studs, and stronger drivetrain parts....at which point I will be needing some sort of unibody bracing as well....see where it goes?

 

It is so thrilling to creep up on total destruction only to get away clean for one more day!

[Guest bastaad525]

yeah the BEGI FMU can definately provide plenty more fuel than I'm using right now, found that out when I tried running it w/o the restrictor... BAD bogging and smoking at 13psi of boost. And the MSD fuel pump is up to the task as well. I don't even know what to worry for as far as running the 80psi of fuel pressure... I don't think it is really hurting the pump, but about injectors 'blowing up' or blowing fuel lines? I dunno but I do love the FMU, installed easy and works great.

[lifegrddude]

Haha I'm sure I have 370's, lol pulled the last 4 off of the SVO myself. My fuel system still needs to be upgraded though. I'm still using the stock pump and fpr so I know the pump is probably being pushed pretty hard when I use the higher boost settings. I'll redyno my setup whenever I get a breather from class. At 9 psi with the intercooler, from what I can tell is that now I'm running super rich up to 5000 revs before it leans up a bit. At 4000 I see an ocassional black cloud. Whenever the heck I get around to dynoing, I will use the 9 psi setting and see if anything has changed. Here's the dyno sheet from my run last year with no intercooler.

 

http://dynoperformance.com/search_details.php?ID=407

 

John 82ZXT