clint78z
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Posts posted by clint78z
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Guys before you go into COMPRESSOR sizing speech, he is staying with the 60-1 hi fi COMPRESSOR.
Randy is dealing with the other half of the turbo EXHUAST TURBINE size. A stage III turbine should be find somewhere in the .63 to .69 a/r ratio. One optiion you could do is leave your tiny turbine alone, get a big external wastegate. When you have a big bypass, the restriction will not be very much restriction at high load conditions. Be sure to get manifold & turbine housing ceramic coated (increased heat to the wheel means better spoolup time).
I wouldn't go stage v on a road race car, that is more suited to a drag application.
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A 2" body lifts looks pretty decent, if there is still no room you could route the crosover tube under the tranny.
If you flip the exhaust manifold that might work, might bang into the A/C pump which is around the same position.
Mabey I will have another look under the hood.
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If you could get it not to leak oil, it probably would be half decent. I would take every last strange doo dad of the engine stip it bare bones with manifolds and use aftermarket efi, and use throttle cables instead of that abortion linkage setup. It's very heavy since it's cast iron, probably it's biggest penalty.
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Might be my twisted sense of humour but I like this one.
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Keep us updated, I have an 89 pathy and have seen a couple junkyard zxt motors. Motor mount was the big one I saw. The oil pan may be different due to the front diff. Power steering and A/C are probably not in the rigth place either. So the turbo doesn't hit the frame rail ???
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Well here is how the igntion sytem works, all components of the DFI are almost identical to a Chev 350 TPI computer.
The engine cranks over spinning a reluctor in the distributor(dizzy). This creates an AC voltage which goes to an 88 Chev pickup module made for Electronic Spark Timing. The module delays the igntion firing buy a set amount. Once the engine spins over 400rpm from the reference wire on the module, the computer bypasses the module and takes over ignition timing.
Setting the dizzy position is done one time, it syncs the timing on the screen to whats actually on the balancer.
Here's a clip from the manual
9)Set timing-When setting the timing on an ACCEL ECU, it is critical to make sure you synchronize the timing between the harmonic balancer and the base timing matrix. If this is not done, the timing program that you implement may not be accurate. To synchronize the timing, first enter the ignition menu and save the current timing map in a subfile by executing "save ignition map in a file" routine. This will allow you to revert back to the original timing program without reprogramming the whole ECU. Once the map is saved and titled, return to the timing matrix and press the "E" key to place CALMAP in edit mode. Since the timing map interpolates values from one cell to another, it is essential to make a set timing map of one value. It is usually best to use a value of 6 degrees for Chevy's and 10 degrees for Fords.
What ever value you use, convert the whole matrix to that number. You will now have a map with all the same numbers. Start the engine and let it idle. With your timing light hooked up, physically adjust the distributor until the value on the dampner reads the same as the value in the boxed area below the timing matrix. Please note that during this initial set up procedure, we have already zeroed the idle spark function. If you are just going to check the timing for sync on a vehicle and not executing the complete base set up, make sure you raise the TPS to over 1.5% to disable the idle spark function. It is easier to disable it this way in lieu of erasing an established idle spark program. For the initial set up you should choose to zero the idle spark due to the fact that it has not been established as to what degree it will be needed. When the timing procedure is completed, return the TPS to a setting of 0-.5% and re-enter the already saved timing map by executing the "Program the ignition from a file" routine.
The computer controlls the firing event of the coil, it fires whatever degree BTDC you type into the igntion map.
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Agh role playing well D&D is not my bag, but 2 ladies in school girl outfits have been known to spark my intrest. Wink wink, nudge, nudge, Say no more, say no more ...
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Yes you are right on the lean reading, wasn't thinking of that correctly. However checking plugs is still important, since one cylinder could be running leaner and cause detonation on that one even though the combined air fuel ratio of all cylinders is correct. Wideband would be nice, where do you usually park your car ??
Anyhow I just got the timing light into town to check timing tonight.Damned laptop battery has kicked the bucket, anyone got a 1/4 mile extension cord ?? Forces of nature stacked against me, most definately !!
The DFI you can't set the timing on startup, you are stuck with whatever is built into the Chev igntion module. The DFI only takes control after the engine is spinning over 400rpm. I think 8 degrees is the module setting.
Anyhow thanx for the info guys, and setting me straight on the misfire lean reading.
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Thanks I will probably pound my head against the wall a bit more. Trouble is right now I don't trust anything on the car. It is running rich right now, and I am not sure it is that way because the ignition is not doing it's job or I have too much fuel dialed in. I would like to get a scope on the igntion to make sure I am getting proper voltage and the pattern looks good. Do a fuel pressure test to see fuel pump is good. When I am sure all mechanicals are good I will start messing with the programming. Right now there is no TPS sensor yet.
I got a map from Tim78zt his car has been dynoed, but it is very rich in the mid rpm to the point were it makes your eyes water
. Then once it hits 3 1/2 grand and 2 psi boost it pulls like a freight train. He has a different turbo and intercooler, higher compr pistons. I compensated for the injector and fuel pressure differnce in my maps. I scratch my head why mine is that far out. Since I don't have the TPS yet I can't switch into closed loop, and it doesn't give me that extra shot of fuel on throttle tip in. Mabey I am just being a wuss about pulling extra fuel out, I guess I just keep tack of the plug readings and O2 outputs. Plans are to take it to the dyno once I know everything is tip top
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Yes I do have an O2 sensor and display on my laptop. I am aware that above .5v is rich. However if you don't have a good spark to ignite all the mixture, you will get a rich reading as well. Or if the ignition has a miss in it, it will also give rich readings as well.
On the open chambered heads like the L6 benifit from more igntion advance than newer cars. Trouble is if you go too much, detonation will occur. Newer chamber design is much better against preignintion happening. The ignition goes 40degrees at 0.5bar and 2400rpm, basically light cruise conditions. Benifits of this are better gas mileage and tip in throttle response.
Once I get to 1bar it is back to 36max.
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There is another 8mm bolt that keeps that lockdown plate on the distributor loosen it it will give you a little more adjustment since it is sloted as well. It hidden under neath !!
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Stock distributor with mechanical advance locked out, and vaccuum advance adjustable to set intitial timing. For timing you set the whole map at say 15 then when idling you hookup the timing light and adjust the mark on the balancer to 15 using the modified vacuum advance mechanism. I did this and it was good but seems to have changed since I have driven it. I have to reverify.
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I had some snags putting in my Accel DFI, with crappy instructions. I got it running well then a series of stupid things just kept getting worse & worse. 2 injectors died, so I got new ones. Then I found the chip tooth on the dizzy reluctor was giving me erratic igntion, so rebuilt dizzy went in. Still bad then after a ton of diagnosing found that the Chev 4 wire Igntion module had 2 plastic pins that must be removed to get a proper ground. Then it ran good for intial tuning, as soon as I try and take the car away from the garage ugh running crappy again. I will not blame the DFI yet, I won't until I know it is that for sure. It sure makes it hard to diagnose with all this new stuff. It started out real good and just seems to go backwards from there.
There is no one remotely in my area to come to my rescue, and I can't exactly take it to a GM dealership or nissan. I am waaaaaaaaay past the point of amusement. It's probably something dumb and small but indetectable. I am very good with a multimeter, and wiring diagrams but I think I need a scope. I have been through the system 1000 times can't find anything wrong.
So I have some questions I need to be verified.
Base timing should be 20 BTDC at idle for an 81zxt, timing varies up to about 40BTDC. Is this right ??
I set up the distributor so the rotor is pointing at #1 cylinder at 20BTDC, and used a lockdown adjustment to set timing by moving the reluctor ring on the vacuum advance mechanism. This is known as setting rotor phasing.
I used a timing light to verify that the timing mark on the balancer and the screen were the same.
It has 6 new injectors, 1 new distributor, 1 new chev 4 wire ignition module,new igntion wire, new MSD blaster 2 coil, new cap, new plugs, a new fuel filter (old one looked good when torn apart).
I haven't verified fuel pressure, quite sure it's not a vacuum leak it go a new intake gasket, and leaks before TB don't matter on MAP sensor system.
It seems like it is changing timing, the lockdowns for the dizzy seem solid. I have to put a timing light on it and reverify. It gives starter kickback like it is firing at the wrong time. That would be a pain in the ass if I was sold a bummed DFI that couldn't keep proper timing.
I think I know this system inside and out, but the car begs to differ. If anyone has any helpful hints I sure could use them.
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It does have notable differences, like direct injection whic varies the the injector angle. Meaning more power, better milage, and emmisions. This is a pretty big step up in combustion technology.
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Joe Satriani is a genius, he has taught so many guitarist it is not even funny. My jaw dropped the first time I heard surfing the alien. Can't forget Eddie, Mark Knopler, man there are so many
Any Stevie Ray Vaughn, BB King... fan should listen to Jordan Cook or better yet see him live. He is from my home town Saskatoon and toured with BB for a year in Europe. I saw him at 8 years old belting out Mustang Sally, everyone knew he was special. While I am at plugging home town bands Wide Mouth Mason is another good blues band.
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Yeah what a peace of junk, better give me the keys and let me drive
It's got 150hp at 3000rpm that's what my stock Z ever put out total. I hear the supra's are a dream to own as a high power street car, comfy, nice ride, good handling. Bit of a pain to get porky off the line but once rolling a sweet car. STOP GRANNY shifting you guys, it's not an 8.0l V10 WIND IT OUT. Personally when I want to go fast, I push in the clutch and downshift. You are going to have to know what you are doing with this kinda power, but you will have to with most 700hp cars anyhow. Anyone not happy with their T78 supra, I have spare room in my garage.
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There are big differences in a 2.0l DSM and a 2.8l L28et. We have both in the family. The 2.8 is far superior off boost and has better low end. The L28 will not rev like the 2.0l, the cam just won't let it, and it would be the first to break a crank.
On a full out modified race motor there are other hidden factors that limit a motor. Crank resonace limits the rpm and sometimes limits horspower.Main bearing and cap distortion limit how much power will be made before destruction Combustion chamber design is a big factor on a turbo car. The new heads can take way more boost before preigntion happens. The 2.0l DSM is a 4v head and is more effecient. How the head is bolted on limits the amount of boost that can be run.
Size isn't everything you have to know how to use it too
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Mabey those are alcohol injectors, or he is using nitromethane in the tank. Pehaps a big ol bottle of NOS. That could account for another 300hp. Perhaps the whole car is gutted ?? It may be possible but I am skeptical until I see a timeslip and more info.
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Very true JeffP that those factors do affect how the turbo will respond on your car.
1)Diameter of wheel, moment of inertia.
2)A/R ratio, affects pressure drop and speed of gases, smaller is quicker response but there is a point where the pressure drop is too much affecting high volume flow.
3)Wheel design, number of blades, pitch, spacing
Some of these variable can be hard to pin down what affect they will have on your engine package. The really good turbo guys know and won't tell, even then they can't always predict without testing.
The simple fact is you need to pick a turbo that will flow enough air effieciently enough to produce 600hp. Why even worry about the other factors on a turbo that can't flow enough to make the power you want.
I do think it is cool to see how far you can push something you already have. My jaw dropped to see Scottie push his stock T3 into the 12's. The T3 is not meant to do this, and died.
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That's a pretty good price 240z turbo, I can't believe the price some places quoted me when I was looking into stuff like that. Hey James what amount of boost creep were you getting on your old 57mm hybrid. I doubt that I will get as much since you had a better intercooler. Getting a good wastegate is a must, I hear some of the lesser quality ones can fail due to the intense heat. Just conquered igntion gremlin last night, improper ground on GM HEI igntion module. The two plastic dowels had to be shaved off to make the case ground properly.
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Play nice don't make PeteP give you a
Let's have a pint and continue on James and TimZ are right about the analogy for wastegates. LockJaw think of turbo flow this way. you turn your tap on full blast in your sink. As the water goes to the top you try to open the drain. If the drain isn't big enough the sink will overfill. If you barely turn on the tap low flow it will be easier to controll it this way. Sometime a couple of psi boost creep is all right, but at higher boost can be deadly. An external wastegate will allow you to use full potential of the turbo safely.
There is so much misinformation about turbos, but the information here as a whole is very accurate.
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Evem my old Robbie The Robot Accel DFI can run in wideband closed loop. Not sure what type input voltage it is looking for, the NTK sensor is fairly new but cheap. It could do alot but lacks good datalogging speed and graphical software for it.
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Most vibration dampers have a certain shelf life, and a rated number of hours until failure. The rubber starts to dry out after so many years even if it is never used. Don't bolt on a straight pulley, you are just asking for trouble. It always makes me cringe when I see unorthox doing this to try and get more power, definately a high rpm reliablity no no. The fluidamper seems to make a bit more sense to me, seems less likely to wear out.
Good comments JohnC, doesn't the added rod end angle and piston skirt tipping add more stress to the crank. The weight difference isn't that much, they are all damned heavy and long. Luckily Nissan blessed it with good balancing and a solid forging.
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Okay - the compression ratio is what determines the combustion efficiency of your engine (i.e., how much power you get by burning a given amount of fuel). Higher compression ratios are more efficient. The problem is that higher compression ratios also result in a higher temperature rise as the fuel/air mix is compressed. If you go too high with the CR, the temperature of the fuel/air mix will get high enough for it to ignite, causing detonation.here is another good one, Compression, what the heck does compression have to do with all this, and combustion chamber size. I did a little off the norm for these engines. I upped the static compression on my engine, and you know it worked out very well for me. A similar setup to what I have takes 6 more psi to develop the same power. Combustion chamber, there again, you will be able to fill more air and fuel if it is bigger.
Interestingly, if you look into the thermodynamic equations for the Otto cycle, you'll find that the amount of temperature rise is dependant ONLY on the Compression Ratio, hence the final temperature at TDC is determined by the temperature of the air at the beginning of the cycle, and the CR of the engine. Contrary to popular belief, it is not dependant on the pressure that you start at. Read that a couple of times before shouting that I'm full of sh!t
. The problem that turbocharging adds is not the pressure, but the fact that it tends to increase the starting temperature of the combustion cycle.Okay - well I thought it was interesting, anyway.
As far as the combustion chamber size thing - do you mean displacement, rather than combustion chamber size? They are two different things. Larger displacement will do the stuff you mentioned re: getting more air/fuel in. However, a larger combustion chamber by itself will only result in a lower compression ratio. While this will give you more resistance to detonation for the reasons stated above, it does not cause more air/fuel to get pulled in.[/QB]
TimZ you are so full of it your eyes are brown
Good discussion and TimZ is absolutely correct about the Otto cycle. T1 [V2]n-1
__= [__]
T2 [V1]
The point I was trying to make about max boost and rpm TimZ explained better. The easiest units to work with when doing complete systems like this, think mass flow (it never changes unless you motor is capable of destroying mass
)I always start with mass at the air filter and that way you can check later on in the system if your volume calc's are correct. Gone are the days of big turbo huge lag, with a good amount of research you can have your cake and eat it too.
Let's have a pint and continue on 
. The problem that turbocharging adds is not the pressure, but the fact that it tends to increase the starting temperature of the combustion cycle.
HeadGasket Questions
in Miscellaneous Tech
Posted
The problem probably isn't the type of head gasket, it's that you allowed preigntion to take place. My philosphy is that the head gasket is like a fuse, it's the first to blow and tell you something is wrong. It's alot cheaper than those pistons you have got in there, check fuel & timing before you get big holes in those nice pistons.