TimZ

In general, I think the farther down the exhaust path you join the wastegate back in, the better. For one thing, the farther down you go, the lower the backpressure is at that point. If you go very far, though, you might want to up the size of the wastegate pipe a bit.

This time I double checked - per the FSM, this is backwards. .010 and .012 is the warm spec.

Thanks, James! Yeah, mine always seems to make about the same ~480 lb-ft. I've just kept trying to move the peak higher and higher...

I need to double check, but I think you have the hot and cold backwards - it's not intuitive, but cold clearances are tighter. Also, I prefer to adjust clearances cold - it's definitely easier on the hands, and you are guaranteed of getting constant temperature from beginning to end. When you adjust hot, the head temp is pretty much always considerably cooler when you finish than when you started.

I tried several different things to try to get the temps down - I advanced the timing as far as I dared, which had helped on my last setup, but I was now several degrees more advanced than before, and didn't feel like it was a good idea to go any further. I tried retarding the cam timing - no help. I ran the mixure down to 10.5:1, and that seemed to be the most effective, but I was still running at ~1650. I thought I remembered the conversation with the dyno operator being about Grand Nationals, but I could be mistaken. The overall gist was that it wasn't as uncommon as I had thought for high effort turbo engines to run EGTs that high, and maybe even a little higher. I think I had mentioned this before, but since this is a new EGT with its probe in a new location which is more directly in the flow path, it's entirely possible that my old setup was also running this hot and it just didn't show up on the old gauge.

at the turbine inlet, directly in the flow path

Pretty friggin' high... on the best run, EGTs peaked at ~1750 degF The last run peaked near 1800 degF with 12:1 AFR. I was kind of freaked out by this, but the dyno operator/shop owner assured me that this was common for the Grand National guys, and also on a couple of other high output turbo cars he had tuned, which were all holding together just fine. The car did hold together and put out some good numbers at those temps, although i don't know if I'd want to hold it there for long periods of time...

Simple - I live in Detroit.

Well, I see that the second guessing has begun on zcar.com, so maybe I need to add some additional details... For the first several runs, I was running way richer than I had been when I street tuned - the culprit was later found to be that the manifold air temps were considerably higher on boost than what I was seeing in the real world - like peak temperatures of 132 degF vs. 94degF on the street. This was not being compensated for. My initial target for AFR was 10.5:1 and the car was in fact running down in the 9's for the first several runs. If you do the math this makes sense given the temperature difference. The first run netted "only" ~501rwhp. The reason for the rich target mixture was because of the high exhaust temps that I was seeing with leaner mixtures, as was discussed not long ago in this forum. For the next several runs I was slowly dialing fuel out in order to get back to something sensible, and then after talking it over a bit with the dyno operator (owner of the shop), decided not to worry quite so much about the exhaust temps that I was seeing, and tried leaning out a bit more to see if there was any more power there. There was. The next to last run was the one that I posted, and it was in fact 11.5:1, verified by TWO different, seperately calibrated wideband sensors. There was a spot just after boost hit that went a little rich (~10.6:1), and both widebands correlated very well. The last run was leaner still, running closer to 11.8:1, but still had the same rich spot just after the onset of boost. this run didn't net any more power, and had slightly higher EGTs than the one before it, so I went back to that cal and called it a day. As far as fueling goes, I'm running Ford Motorsports 150lb/hr injectors, derated to a base pressure of 32psi. So, when derated to 32psi, they should be flowing 128lb/hr at that base pressure. My old 72lb/hr injectors went static at around 20psi and 7000rpm. I was running a base pressure of around 50psi on those, btw.

The pistons have a BIG dish in them - see below. My N42 has had a fair amount of work done to it, it flows really well, and it works just fine for me so I don't see any reason to change it. (I don't want to start another N42 vs. P90 discussion ). The backfires are from the rev limiter - when it cuts fuel, it dumps a bunch of oxygen into the exhaust, and if there is unburned fuel in there it ignites. Interestingly, at the end of the session, my exhaust was very noticeably quieter than when I started - I think the backfires must have reshaped the insides of the muffler somehow. The effect was there for the last three runs which made the most power, and the datalogs don't show any appreciable difference in turbine inlet pressure, so - bonus!

I uploaded a video to uTube of the session (not as exciting as ZGad's drag race vids, but...)

7.5:1

if you pull a spark plug, is it wet?

No, 11.5:1 seemed to be pretty much the sweet spot. I would have liked to have had the ambient temps a bit cooler, though...

I'm pretty pleased with the results... this was done at ~85degF ambient, 25psi boost 94 octane sunoco gas no nitrous no water or meth injection it's a stroked L28 with an N42 head I'll fill in a few more details later, but wanted to get the results out (okay, I'm a little pumped:mrgreen:) EDIT: 100mph corresponds roughly to 5000rpm The rev limiter was set at 7600rpm and this run ended on the rev limiter.

My car only pulls ~5"hg at idle, and I do not have this problem. My PCV system is plumbed essentially like the stock setup - block vent to the PCV, which is plumbed to manifold vacuum, and crank vent to the turbine inlet. Both have oil separators inline, but otherwise the same configuration as stock. Find the actual problem before looking for exotic solutions - the stock setup works just fine, so long as things as plumbed correctly, and nothing is clogged. Adding a pump at this point would only be a very expensive and overly complex band-aid. Are you certain that the PCV valve is plumbed correctly? If it's check valve is backwards (possible if it's not the stock pcv), you would be pressurizing the block, for instance. Also, somebody else already asked this I think, but how long are you giving it before concluding that it's still broke? If the turbo seal (or whatever) dumped a bunch of oil in the exhaust system, it would proably act like you describe (i.e., doesn't smoke at startup, then starts smoking after things have warmed up a bit), and it could easily take 30 to 45 minutes of freeway driving (constant load) to clear it all out. Driving for 5 or 10 minutes is probably not enough. Idling for 5 or 10 minutes is definitely not enough.

First things first - when you say it starts for 2 seconds, how is it running for those two seconds? Is is firing on all cylinders and then it dies, or does it just kind of sputter and then do nothing? Start with the simple stuff - are the fuel injectors injecting fuel into the cylinders? Is it getting spark?

TEC3r here - I do know "a little" about the TEC2, too...

That is true with the stock fuel pump, as it has a check valve built into it. However, aftermarket pumps might not. Mine don't and my fuel system acts the same way.

I've been very happy with my Cunningham rods

LOL that's what I thought of too, but I didn't think anyone would get it.

Yep - not to mention the addition of the 2mm head gasket (I'm assuming that's different from before, too)

You were reading correctly - I literally have less pressure in the exhaust manifold than in the intake. This is not a situation that I am used to having. I've been thinking about retarding the cam timing, but haven't gotten to it just yet - hopefully this weekend. The thinking behind this is that keeping the exhaust valve closed longer will result in more energy being used in the power stroke, thus lower EGT when it does open. So far, I've found that I can keep the EGTs down to ~1600F by running a really rich mixture (~10:1), but that is killing the power. I've found that "leaning" the mixture out to ~11.5:1 adds a considerable amount of power, but the EGTs go back up. Also, I've found that adding timing has helped to an extent, but I'm not too comfortable with advancing any farther than where I currently have it.

Now that the weather is coming around, I've been able to start the dialing in process. Here's a bit of confirmation of my suspicions... I instrumented the turbine inlet pressure and datalogged it along with everything else. It appears that at ~24psi manifold pressure, I'm seeing anywhere from 16 to 20psi TIP (!). Exhaust temps are still running a bit high, but damn it's pulling strong... Tony D (or anybody) - any insight on tuning strategies?

So far my new exhaust has been working very well, if a bit loud... I instrumented the turbine inlet pressure, and so far I'm seeing TIP at about 2-6psi less than manifold pressure at 24psi of boost...