So.... I have been at 14psi for a month or two since i did my gasket replacement. At stock timing, air/fuel at mid to high 11's, while spraying meth/water. I got some knocking. I lowerd the air/fuel to low 10's and no knocking, but thats pretty rich in my opinion (could be wrong). Now my theory as to why im knocking even with meth/water and sub 12's a/f, could be because my turbo might be running out of its efficiencly range blowing out uber hot air, can this be correct? The turbo I have is a t04b, .69ar turbine, .60ar compressor with 69mm wheel. I have a few psi's of pressure drop, so i estimate the turbo to be actually putting out about 17psi or so.

What do you guys think? i already oredred a larger nozzle for the meth but wanted you guys opinion.

 

I had that turbo. Its very hard to find a compressor map for it but i did find one.

http://www.vwparts.net/CB7488.html

 

I cant find my excel doc with details of my pressure ratio and air flow, coming from a 3.0, and turbo lets say putting out 17psi, where would that land me on the map?


btw, thanx. iv been looking for that
Edit:
well i did a really rough estimate and it puts me at about 40lbs/min, and pressure ratio of 2.1. I just dont know if thats spot means its out of its efficiency (not too good with these maps yet)

 

No problem. Took me awhile to find it, i bought that turbo and had absolutely no idea what the hell it was, but got it for a steal and freshly rebuilt.

Anyways, ill let someone else chime in, but id venture to say your approaching/approached the limits of that turbo.

I think its time to move into Holset territory

 

Trust me . he is going to move to holsets one way or another.

 

I believe that 3.0L maximas have a 35-38 cfm.

 

Even if you are out of the efficiency of the turbo, stock timing is too much when you start running that much boost. I am running reduced timing at 12 psi max and running water/meth injection in the summertime to keep from detonating.

 

96blkonblkse: gimme a week, and you'll see a holset

How much timing are you reducing? I reduced 10 degree's and ran without the meth/water, with air/fuel mid 10's, and i didnt get any knock. tried reducing less timing but it knocked a lil bit, so i guess i should stick to 10 if i dont spray meth. since im running the meth I wonder how much timing i can get away with.

 

You're probably getting pretty far to the right of that map meaning more and more hot air as you know. There's no reason to run your AFRs in the high 11s in my opinion, it gains you absolutely nothing - no power whatsoever. I've dyno tested it on a couple different VQs and maxmaxima91 has on VGs and hondas, lots of testing. All it does is reduce your safety margin.

I'd keep your AFRs mid-high 10s, pull a few degrees of timing, maybe 4-6 degrees around torque peak if you are tuning FOR the water/meth, or 8-9 degrees if you are simply using the water/meth injection as an added safety measure and still want to be safe if the water/meth stops working, and make your power with boost rather than advanced timing and borderline AFRs. It's always safer to make power with air flow (boost) and less timing/more fuel than flirting with disaster because you've got the flame front running on the ragged edge because of too advanced timing and too little fuel.

 

Cool I was expecting a post from you, valuable information. thanx

So basically instead of making power with timing, just put up the boost.

Now when messing with timing, how exacly do I go about it. Right now how i do is that for example at 14psi, it retards say 10 degree's, but across the entire rpm till redline. Should I only retard timing like that? or should I only retard the most at peak torque and then add more timing as it gets to redline?

the reason I retard it all the way to redline is because the knock I was getting was above 5500 till i let off, which is passed my peak torque. its more like in my peak HP. For now i'll retard 4 degree's, keep a/f's low/mid 10s how i have them now, until i get my new turbo in a couple of days(ftw!)

Nealoc, what I am getting is an hx35, do you think it will run cooler since it probably wont be getting to far right on the map at this boost level?

 

very informative thread, have you tried adding some octane booster to your fuel? Or try running some C16 and see how much of a difference it makes. What size meth nozzle are you using? And what's your meth / water mixture?

 

You retard the most at peak torque and less as you go to redline. Don't start retarding timing until whatever RPM you get to like say 6-7psi of boost or so.

 

Well I dont have easy access to any other fuel, but meth alone should be almost same effect as octane booster and higher octane fuel's. Now my nozzle size, thats a good question. I recently ordered a 6GPH nozzle, because im not 100% sure what size I have on now. I am using 50/50 mix. I spoke with a tech guy at devilsown and told me to try running 70water/30meth, because it will cool better, havent tried it yet

 

hmm, I would go the other way around and use more meth less water......but you're turbo so the extra water could help. But then you're running less meth. Wonder what would happen if you run like 35% water, 35% meth and 30% C16.........damm I have a 380cc meth nozzle, you may need like a 500cc nozzle, was this always a problem? I have heard cases of people getting bad batches of gas.

 

ok, so now question, if i dont have access to a dyno, how can I determine my peak torque, just go off other's dyno? with a working vias on 00vi, auto.

 

Well this boost level is new to me, and I did blow my previous head gasket (not completely but it was in very bad shape don kno if u seen my head gasket), this was probably due to my nitrous days and being careless, i was only at 10psi back then.. Now i wanna do things right.

I believe I also do have a 380cc, but since im not 100% sure i ordered another 6gph(380cc), to make sure thats what i have, and i also ordered an additional nozzle with a 3gph to run a dual nozzle setup incase i need more meth/water.

btw whats your setup like? a/f, peak boost, and mixture your using for meth/water, retarding any timing?

 

^ im using an FMU with revup injectors and got my tune down to 11.2 - 11.4 on a cool night and it dips down to the 10's at like 5800 onto redline cause I added fuel to the curve on the apexi. The fmu I think give me a little bit of an advantage of not running too lean. I am using 60-40 meth-water and a 380cc/m nozzle. That was my old setup. It ran nice.....btw, stock timing and boost would hit 13-14 on a cool night at redline. Not so much on warmer nights.

 

is that the setup which gave you mid 300's whp? 360something I believe.

 

You need to add J&S to protect your motor from knock and get a retune.

 

1. First thing, are you sure your A/F gauge/sesnsor is accurate? I would suggest having your downpipe tapped and check it with another sensor on the dyno. Then compare the dyno data to the readings on your gauge to see how far of it is. Another check would be to use Nissan Datascan to see if your O2 Sensors are reading the same as your wideband.

2. What plugs are you running? You should be at least 1 heat range cooler.

3. Are you running stock compression? If so, you are really at the limit with the amount of boost you are trying to run. Go another step cooler on the plugs will help.

4. What are you running for timing maps? How much timing advance is it running at 4000, 5000 and 6000 rpms? If you are running factory maps, yes you will have a problem.

 

Loren is still posting?

 

Yes my wideband o2 is accurate and calibrated (lc1), also checking with nissan datascan will not show you air/fuel as it is narrowband, and at open loop the o2's dont do anything anyway. but yea thats not an issue. (I have a scanner, thats why I can assure you that)

I am already running 2 step colder plugs bkr7es11, the engine is stock, stock compression n everything, also timing is also stock ecu, which is about 23 degree's to about 25 degree's towards redline.

I wouldn't agree as to my boost level being the limit, others have put alot of more boost through the 3.0 and not be at limit...

I do agree that timing might be an issue which is why im going to go ahead and retard some timing, even with the meth/water.

thanx for ur input

 

streetz what are you using to pull timing

 

I am using an emanage blue

 

well even say at 25 psi on a hx35 is still a winter blast (Cold as ice) I have a hx35 and have ran up to 15psi and I start pulling timing at 9-10psi for a degree per pound and have 0 knock even at around 4200-4600 where it shows to try to knock I pull about 2 degrees per pound over 10psi thier.
My friend says he runs about 45psi on his dodge truck. The hx35 have a very wide range
. Also I m going to guess that the hx35 will be adifferant animal than the turbo you have now at 14psi
Hope this helps

 

yes, 369 untuned.......I then street tuned but didn't get a chance to dyno again.

 

How was your wideband calibrated? Did you use a Horriba or similar to read accurate readings and adjust the gains on your box at different ranges to compensate for the sensor? I have a UEGO 5-wire which is very accurate, but still can be slightly off. I still use a Horriba when I am getting data for tuning. I know my UEGO reads .2 richer in the 11.5-12.0:1 range. Knowing exactly what your wideband is reading can save you a lot of $$$ down the line.

You are correct that the ECU does not use the O2 sensors in open loop, but they are still constantly sampling and you have 2 of them with one located on each bank. What are the voltage readings you are seeing off them? How close are they between banks? This can tell you very easily where your issue is. If you have an issue with an injector leaning out or a coil pack losing resistance, it will show up between the O2 sensor readings. You have a lot more data at your disposal. You just need to know how to use it.

There are those of us putting a lot more boost than that in 3.0L with built motors. It is easily possible to run 20 psi on 93 octane with a 12.0:1 A/F ratio all day long without methanol/alcohol injection or adding race gas...just not on a stock motor or with a stock tune. Open up a stock motor and take a look at what is inside: low silicon content cast pistons that can't take much heat, thin rings tightly gapped (unless they are very old), thin rods with weak rod bolts. Remember you are forcing your engine to do a lot more than it was ever designed to do and there is a risk in doing so. You can check these boards for the number of people who have broken motors trying to push it. You are currently at the limit where most have broken. Just don't be surprised when it breaks.

You do have too much timing to run 93 octane with the compression you are running. You should look at getting an ECU programed to back down the timing. If you want to stick with the high compression then you should have no more than 21 degrees on top. If you want to stay on pump gas, I would back it down even more to 18-19 degrees. You will lose some top end power, but you will find the car with drive a lot smoother all the time. The other option is to slow down the burning in the cylinder by running a 30+% mixture of race gas. Just adding some to the Methanol injection is not enough. You need a lot more octane to slow the mixture burning down. For a test I would suggest to run a 50/50 mixture of 93 and 104 Sunoco unleaded.

 

Very good information and thank you for sharing your knowledge, well appreciated. And yes your right im taking into account the timing, I spent a while last night adjusting my timing on my emanage's table, basically im going to have about 16 degree's at most (considering my log's show timing reaches about 23-25 degree's. im retarding about 8 degree's.) I have the timing retard by rpm vs. boost, so as soon as it get anything above 10psi it starts retarding given certain rpm. I also lowerd the a/f as well, now its going to be in the mid 10's. As for my lc1 wideband, i only have compared it to dyno jets with sniffers, and my lc1 reads about .3-.5 richer.

Interesting about the o2's, im going to look into that.

Would you suggest not taking it above my current limit or boost? I dont wanna get anything higher than 400hp to the wheels, im happy actually how the car performs right now, which based on butt dyno feels like mid 300's, maybe 350-360.



UPDATE: I just got my brand new HX, soon to be installed.

 

^^ oh my ! Let me know whenever your up this way !

 

I wouldn't up the boost at all, just leave it where it is and work on your tune.
From the looks of it, you have the A/F down so get the timing dialed in, increasing boost would throw another element into the pot and most likely throw your current tune off. GL!

 

One thing you might want to look into is your injectors. I was fooled by them once and it ended up killing my engine. At one point i had it were even when i was in the low 10's AFR wise, it was still knocking. It was all due to my injectors being unbalanced,causing some cylinders to be overly rich and others to be overly lean/knocking, yet have the average afr indicate a good safe afr. This was an extreme case and i doesn't sound like yours could be this bad but i may be something you want to look into. And yea for a streetcar, there is really no reason to be any leaner than low 11's it just gets more and more risky... cause all it take is a second to blow an engine.

 

Your right, I might have my injectors checked. They are z32 injectors that I bet have never been cleaned and they have alot of miles on them, even matty had these injectors i have lol.

UPDATE: As i was told, to be careful messing with this current boost and timing etc... The car still runs, however at idle specially in gear it its a little rough, at idle with no load say in park or neutral rpms may be like at 1k, i put car in gear, or even turn on a/c, rpms drop to like 600's. Meaning the engine is having a hard time under load n providing poewr in general, driving feels like it lacks power, im willing to bet compression is very very low. Also the car is blowing ALOT of smoke from the crankcase's, uber blow by. It has always had its little smoke, but now its very bad. Its not worth checking compression, i know the motor is on its way to the grave. So... i got a DE-K on the way to arrive on Sat with 72K miles, 00vi, injectors, coils everything still on it, even sensors. So now to a fresh start.

 

fresh start for the new year! lets see that auto put down 400 without cheater juice!!!

 

cracked ring lands

 

without a doubt. check your injectors before you use them for boost again.

 

What MAF are you using? I see you are using 370cc Z32 injectors, but with a Z MAF or a Max MAF? You should be on a Z MAF which has a higher limit than a Max MAF. In fact, you are already above the limit of the Max MAF. Remember when you look at MAF readings that once you hit 5.0 volts, you are done and you won't get anymore injector.

Personally, I would back the boost down until you get the ECU reprogrammed and not risk the engine. Keep it at a peak of 13 psi. The tough thing with using a retard device is unless it is programmable, you can't get it to respond exactly right. What you really want is to back the timing way back when you are spooling and then start bring it back in once you pass the torque peak. This is the disadvantage of boost indexed timing retard as it doesn't take neough out under spool and then has too much out when you are finally in the power. I would recommend to go rpm based instead.

L

 

You are right about the timing, I had it based on boost before, i can set it to start retarding at any boost. But i just went ahead and did it based on RPM. The only draw back about that is in 1st gear, i dont get full boost, so since its retarding timing based on rpm, it will give me some lack of power in 1st gear. Im expecting the new turbo to spool up sooner and provide me with higher boost in 1st gear so that wont be a problem.

As for my MAF, You are right, i have the maxima maf maxed out, input voltage reads 5v, however output voltage after corrections is not yet at 5v. So for example at 4500 rpm, input voltage would be 5v, but after my corrections the output voltage is 4.65v. meaning its still adding fuel, once my corrections give an output of 5v then thats where i'll start to finding a z32 maf since there wont be any more fuel to add.

For the new motor, im going to be putting 440cc injectors, im really considering just getting z32 maf already and not be having my tuned based on a maf thats maxed out, wanna do things right with this motor. I will be putting in my new turbo this monday, i also receive the engine on monday so a week later or so, hopefully i can start doing the swap and hopefully be running again in two weeks.

 

Yeah just get the z32 because you will definitely be at a higher power level with the new motor and turbo. Sorry to hear about the other motor but it served well!

 

He HX is in, it sounds insane. feels good, im only at 8psi right now. Im not going to do any further testing since the car is smoking alot(out of the valve covers), I just got my DEK an hour ago, so this weekend coming up I should be ratcheting away.

 

Dam its smoking out the valve covers. So wht do you think it is now valve seals? piston rings?. Good luck with the new engine.