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Dyno Baseline

This is the first dyno test of the car. I am happy with the results of all my hard work, and the money spent,what a wad it took to get the car to this point. The readings of the graph are readings at the wheel.
When I first got a look at the horse power I thought, isn't that a little shy of the horse power this upgrade was advertised to do? Then I did the math and added in the 20% loss through the drive train, and sure enough, the car was putting out about 456 Hp. Not to bad, but I was wanting more, but who doesn't want more.
The car pulls well, but I would like to see some improvement, not that what it does do right now is not very good, but I just haven't gotten that feeling out of the car that I like to feel. The car still seems to strugle getting up to speed in my opinion, but then I have always been a power hungry kind of guy when it comes to cars and how fast they run.
Anyway, this dyno results shows me where I need to do some more work for the most part. REDESIGN the whole shootin match, no not really, I would like to see the power curve to come on where it is now, but last up into the 6500 rpm range. There are a number of things that may be causing the drop off in power, and all of them say give me some more money Jeff. I think the next step in the car is to get a good header on the turbo, and then do another run to see just how much it changed. Then it is just a matter of installing the rest of the parts to build what I really want, a 600hp engine and get some real neck jerking power to the wheels. The tranny is a major consideration at this point also, and that is going to cost a bundle, but looking at the torque the engine is putting to the wheels the T5 that is in the car right now is screaming under max load, and I think if I really launch the car hard one time I can make a necklase of the gears off the cluster and first gear. Aint it great? Have a good one.

Here is the most current dyno run.

This last run I turned up the boost to 23-25 psi. I am not sure exactly as the boost gauge was moving from 23-25 and would appear the turbo is out of air. The question on the curve of the hp/torque is a tricky question at best. You could assume the turbo is running out of air, or the cam is not letting the engine breath at the higher rpm levels, or the back pressure in the exhaust turbine housing is getting to the 40psi range, and in that case the turbo could pump 35psi out the compressor and I would not gain anything to speak of. I have noted on other cars that when the turbo back pressure becomes excessive this is what the power curve does. The cam can also make such a power curve in the engine also, so I think the most appropriate step will to get a bigger turbo. I am working for 600Hp at the flywheel so I am going to need about 35psi to get that power anyway, and I can put a pressure gauge on the inlet to the turbo to double check the back pressure. That is about it for now I guess it's time to tear the car apart again, mo' money Jeff, again, will it ever end LOL.
Well I put a pressure gauge on the turbo before I took it off of the car. I was able to get to 23psi of back pressure, and that is exceptional. So the back pressure was not a factor in the power curve for the last run. The turbo definetly is going to be upgraded at this point with a larger compressor, and I have come up with a .70 A/R exhaust tuerbine housing. The turbine housing has been machined to accept the stage five exhaust turbine wheel, so the A/R ratio of the housing has dropped slightly, but that is just what I wanted. That should put the A/R ratio just about perfect for the application. When I complete the upgrades, I will dyno the thing again and see what I get with the larger compressor. I think it is a combination of both cam and turbo, so I will do a pull with the new turbo get those results and then do a cam change based off of that data. I am thinking I am going to have to go with a longer duration on the exhaust side of the cam and that will improve the performance at the higher rpm levels. James made a significant comment regarding the flow rates of the intake and exhaust ports of the head, and in reality that will be the hp limiting factor for the engine.

New Build first test

This is the latest dyno I have completed. I cant say that I am all that pleased with the results. I spent 4 hours on the dyno at a cost of $100.00 per hour, and a $50.00 dollar hook up fee. I wasted my money I think, but at least it got me thinking of a better way to get the car tuned. I am going to setup my own bench and simulate the engine running to get a handle on what is happening.
Lets look at the dyno graph and I will explain what we are seeing. The dyno this time was completed on a Mustang dyno. The first dyno pulls were on a Dynojet. The mustang unit is a much better dyno to use for realistic tuning of the car, it is a load bearing unit that simulates actual street driving much better then the inertia dyno.
The car was run in Forth gear for all pulls/tests 1:1 gear ratio. The testy consisted of running from 2000 RPM's to 7000 RPM's on the dyno for the graph.
You can see that the power starts coming on @ about 3400 RPM, and builds quickly from there. The turbo does spool about 5-8 psi at about 2500 RPM. The black line is the AFR through the pull. You can see that I start a little rich in the beginning. I will complete that part of the rpm range at 14.7 AFR's but for now I want the car a little rich. This is good until about 4500 RPM where you see the AFR increase to about 12- 13.0 : 1 Not good for pushing close to 20psi of boost.

This is where I am having the problems with the Nissan ECU. I am not sure exactly what is happening, but I do have a few clues. The ECU has three modes of operation.
1) Batch fire- two banks of three injectors firing at equil interivals, bank1 then bank2 and so forth.
2) full injection- when the ECU fires all injectors ar one time.
3) Full injection divide by 2- where the ECU switches modes, takes the single injection pulse per revolution, divides that pulse in half, and triggers TWO pulses per revolution.

This is where I believe I am having trouble. The MSD 720cc Rochester injectors appear to be UNABLE to switch on and off fast enough. So what I get for my trouble is a short lean condition, and then a PIG RICH condition.

I have not verified this, but it is clear I need to setup an accurate simulation bench running the ECU real time to see just what the heck is happening at the injector with an Oscope, poke around until I figure out what it will need to fix the problem. So that is where I am at right now with the car, 11-29-06.

Now the dyno itself:
Aside from the screwed AFR curve, the engine was making some good power, 489 HP. The power is on by lets say 3500 RPM, as that is nearly double the power of the stock engine. The power curve to the end of the chart, (I did not let the dyno get to 7000 RPM's as that run the car started to ping, and seeing I had completed a number of runs before that with essentially the same AFR curve, I did not want to work the engine through that spot again for nothing)I got to 6800 or so and shut it down. The power curve, if you look at it looks very good all the way up. You can see the decrease in power as the engine got into the 10:1 AFR range, no problem, better rich then lean right. There is no doubt the cam is breathing very well and continue to at least to 7500 rpm's. Ron Iskyderian and I figured out that grind. I thought it was a little to high of lift, and a little long in overlap, but the lobe center made up for the excessive (some may call over cammed) cam. I think this is the Largest I would ever recommend for a turbo cam for anybody. The grind before this grind is better suited for street use and racing, generally an overall well rounded cam that will give the best of both worlds. The cam I have now in my opinion is strictly race, but I still may be able to play with the timing slightly and make additional improvements. The lowend is still VERY good, and the car picks up gear to gear VERY well.
I did remove the timing on the topend, around the 5000 RPM range, as the guys on the dyno said they heard pinging. I could not hear it in the car at all. But since I could see the lean spot, RIGHT around the peek power, I pulled the timing to 18-20 degrees to be safe while I tuned the car, or tried to tune the car rather. So there was a decrease in the power, and when I get the electronics figured out and corrected, I BET it is those MSD's causing my problem, then I can do the timing curve, AFTER the fueling is correct.

I was building this engine for 600 HP at the crank, looking at this graph, the boost levels, I am really starting to believe this engine is going to produce power if not at 700hp, VEEEEEEEEEEEEEEEERY close to it. So that is about it for now. I am happy about the power curve, this is what I should have had on the earlier DYNO, but the cam was killing the power and made for a peeky power curve. I am not all that happy to find that there is an electronic problem with the ECU and injectors. I will keep at it, and if it is possible to get the results I want, good for me. The other options I had is after market(and I have just the system to use) or go with a 1990 M30 ECU because it is a little different then the Z31 box, in that it fires the injectors sequentially and that should take of the problems. So there is a solution, I think, with the Nissan ECU, and that is really what I want to run. So we will see how it turns out.

Latest Failure

Again no Joy! this car for whatever reason doesn't want to see things my way! I was happy to see the numbers at 20psi of boost, but the damn thing is still misfiring! I had the designer and tuner of the new fuel management at the dyno tuning the car. I was driving real fast to no where! This is the most power recorded on my car. The last tuning incident (and since it has failed the last two times, and since I have now spent about 3K on the whole deal, I CHOOSE TO CALL IT AN INCIDENT!) This car! what will it take. We did all of the standard stuff, change plug gap, change plug to colder range(the plugs I had been running glased) with GET THIS Champion plugs. NO JOY! I am going to have to do more testing to assertain the problem, or defficiency. Still this has been the best dyno run for the car even though it was misfiring. I think this was the last run that we got to @ 20psi of boost, and even then I could feel the slight misfire, but what the hell, its only money Jeff. Maybe next time big guy! pisses me off, oh well I guess that just the way the old ball bounces.

Final Test Results

I got back to the dyno after buying a 250 dollar external boost pump for the car. I also did determine the NGK plug wires and boots were my problem with the car. I installed MSD boots and magnacor wire and that did take care of the misfire. The plugs are a BKR8EIX Iridium plug and they did very well. The car did well on the dyno, it did surprise the tuner a little. Seems like I have heard before the engine want to ping in the 4-4500 rpm range and again in the 5-5500 range of the rpm. Good old L28 LOL.
I was able to run 26psi of boost or so, but the car would not make any more power after 22psi of boost. We are thinking that the back pressure in the exhaust has something to do with it, and I tend to agree. Then talking to Bernard on the phone about it, he mentioned that I still have the .82 A/R exhaust turbine housing for my turbo. DRRRRRRRRRRRRRRRR, oh yea LOL. I am running the .63 A/R turbine housing. Maybe there is more power to be had with that change, I also tend to thing there is, but that is one of the nice things to try.
I am overall pleased with the results of the build. I think I was just about spot on with the hardare for 600hp.
So the last two pulls on the dyno, I'm in the car getting ready to do the pull, and I notice that Lance moved away from the pc on the side of the car. The guy operating the brake disappeared, and Nick was hiding around the side of the building. I just thought you know guys, you don't exactly inspire confidence here LOL. The car did just fine.
The last pull, the dyno glitched at about 5500 or so and I lost the last part of the graph to 7K, but you can use the previous graph to see how the cam comes on and its peek, well getting close to peek RPM LOL.The dyno guy said the total @ 7K was 658 HP at the crank. So no problem.
Ron, you were correct, I am having good luck with this grind as well. Robins clutch held 509 foot pounds, good job there. Nathan the cylinder head worked perfectly, excellent!Brian, the damper held in there just fine, sweet.Dave Robello did an excellent job on the rotating assembly.

AND ALL OF THIS--------- with my stock, restrictive turbo intake manifold, my small intercooler, small intercooling piping, and my small turbo.
I had a good day April 11, 2008.