EricF

Doh! Yeah forgot the EGR port part. I bet with an R manifold and a nice sized turbine wheel you're in the 1.1:1 range...

OK, you're wrong and here's why. You are usually right, this is disappointing though. Simplistically: The piston travels up in the exhaust stroke (4th stroke of a 4 stroke motor), the exhaust valve is open and it's pushing exhaust gases out into the exhaust to meet the turbine wheel. As it reaches TDC, the exhaust valve starts to close and the intake valve starts to open. As the piston starts going down on the intake stroke, there's a point where both valves are open (overlap). In a *turbocharged* engine, the air in the turbo manifold in most OEM-ish setups has a higher pressure than the intake manifold (as Lucky effectively described and demonstrated with firsthand observations). So, do you think the air filling the cylinder is going to come from the intake valve which has less pressure on the other side of it? Or do you think the higher pressure in the exhaust is going to cause the cylinder to be filled from the exhaust valve? This is one reason why turbo cams, NA cams, and supercharged cams all have different profiles for similar power output goals. Turbo cams designed for OEM-ish applications pretty much always have low overlap for this reason. More extreme turbo cams where very large turbine housings and better headers are being used will have more overlap because the EBR (exhaust backpressure ratio) will be closer to 1:1. Lucky, that is awesome information. Do you have an R manifold? I wonder if someone could check on a conical-outlet housing setup with everything else being equal.

Just remember, the most frustrating part of doing it without the cam holding tool will be when you release the tensioner and it tightens the belt revealing that one cam is actually a tooth off. Then you have to remove the tensioner and do it all over again It is not as simple to do it without the cam locking tool. But if you are careful it shouldn't be a problem. Don't get all upset if you mess up the timing by a tooth or so though, just do it again.

I am really enjoying this thread you guys. It has got me thinking of a higher flowing head on my car, and of a super budget longblock And of continuing to tinker with these damn cars when I really should be selling mine and getting an expedition or something to pull my boat with You bastards... I love you.

If the TPS value itself is used in any of Motronic's calculations it could matter if it's off by 15%. However I'm really not sure if it is or not.

It's all pretty easy, compressing the tensioner might be the most awkward thing to do. It's hydraulic, so you need something that can push on both ends of it with a lot of sustained force. The methods I've used in the past: 1) Valve spring compressor, 2) Big bench vise (probably best), and 3) Floor jack pushing up onto the bottom of the car (most readily available and basically what I do these days when not at the shop The water pump shouldn't be difficult, just a handful of 10mm bolts. The tensioner pulley is easy, I think it's two bolts although I don't really remember. The most PITA thing I think is going to be physically getting the old belt off around the crank pulley. Always seems to be something you wrangle with for whatever reason. When I do the NA cams, I'll try to at least do a writeup on everything I do.

Guys, the stock turbo cams are very anemic. The NA cams are slightly less anemic, though they do have a good amount more lift. It's a no brainer. They are better, period. Whether it is worth it to do them in your car depends on your confidence, skill level, schedule, horoscope for the day, etc. It's no more difficult than doing a timing belt IMO. Actually, it's easier IMO. Hussein, you are a saint for encouraging people to do it the right way. However, I have had the cam cover and timing belt off about a jillion times in these cars, and never used any of the special Volvo tools. I pull the valve cover off when the engine is all lined up on TDC, then it just takes a quick visual check that the crankshaft is still lined up, re-installing the cams and the cover, compressing and installing the tensioner, making sure the gears are on the right teeth so when the belt re-tensions they will be pulled to their TDC marks, and that's it. I have *never* stripped the threads in a cam cover bolt when reinstalling the cover. It is tedious, and you absolutely have to do it carefully, but as long as you tighten a center 6-8 or so bolts just a turn or so at a time by hand until the cover is snug against the head, you'll be fine. I think I could do the cam swap in about an hour's time. I would get a chance to test this estimate, but I think I'm going to do my timing belt and water pump at the same time. As far as before-after numbers... I have a pretty good setup to show significant gains, but it's also a setup that everyone will probably dismiss the results in discussions as I'm "heavily modded" (whatever that means ). The bottom line is the cams are meaningfully more aggressive, and as long as you can optimize the cam timing for your intended powerband and tune, you will see gains. In my opinion people being wishy-washy about their confidence in doing the swap is why we see sooooo many of these annoying threads and nobody actually doing anything. If anyone wants a hold-the-baby's-hand walkthrough on doing the cam swap with hand tools, I'll write one up. Until then, everyone stop pretending like nobody knows if they're actually better or not. They are.

In VEMS, my throttle position at rest is 10%... Even if I re-calibrate it. WOT is right, but it starts at 10 and I'm not really sure why. You'd think with a fresh calibration that it would read 0 and 100 in the right places.

How about some octane to see if it consistently increases your logged timing If it does, you are getting timing pull from knock. If it doesn't, then that is not the case... If your timing values from the logger are correct, then I think it's obvious that you are getting timing pull (compare your timing tables to your logs by RPM/load, and if they are lower, obviously they are logging incorrectly or are being pulled down by knock).

Or, "Why you should just start preparing yourself for standalone management *now*" :lol:

The EGT is my hangup... If he's getting negative timing, his EGTs will be off the charts, especially with that much boost and load. That's why I think there is something wrong with those numbers. I also think the car would feel pretty anemic even with 25 pounds of boost if it didn't have any timing at all. Heck my car doesn't even feel that fast and I'm running a fixed timing map as posted a couple pages ago :lol:

I would suggest tailoring your datalog to show you as much as you can about what's going on now with your setup, before you start changing variables. I'm still very leery of those timing values, I think either the logged values have to be wrong, or there is some massive timing pull occurring for one reason or another. If they go up consistently when you increase the octane, it is likely timing pull from detonation.

Does that dyno shop offer tuning by the hour? Maybe their "3 pulls" is really high to get people to buy tuning time...

Hi Hussein, I have a request! Could you find some 100 or 104 unleaded, or spike your next tank with a hefty dose of toluene to bring the octane up a bit? I would be exceedingly curious to see the timing datalogs from that tank of gas. It has been a long time since going to the track frequently with a Motronic powered car, but I do recall that between my experiences along with those of Joseph Essaye and a few others, we would consistently get much better top end pull with some added octane. This would be a wonderful chance for us to see if there is actually some light knocking going on that is pulling your timing back. Especially since Jan (JCViggen) has said MTE seems to tune with the assumption that there will be some timing pull...

Your thoughts on timing are off quite a bit If you follow a stock map's 25% line, it will start at 15 degrees for the 500 RPM bin, and climb to 37 degrees by the last bin. The 100% line starts at 12 and climbs to 26... The last bin is 6200 RPM btw. Especially in the higher RPM range as you get further away from the torque peak, you need quite a bit of timing even on small fast burning chambers like these with centered spark plugs. Here is my current timing map, I think it is a little too conservative in a few places. (I'm running 17-19 psi boost, so at WOT by 4000 I'm in the 200-230 KPA range. I have a suspicion Hussein's datalogger is lying to him about timing. Or else it's all being pulled for some reason.

If I were starting with a bone-stock 850 turbo, I would go one of two directions. 1) bolt on a 19T, intercooler, good software, and convert to manual transmission 2) bolt on a nicely sized garrett turbo, wire a 'decent' (for you Charles, I mean 'cheap') standalone with a modified stock gauge cluster, intercooler, manual swap and NA cams These are the two best bang for the buck setups for a stock longblock. The first will get you 280-290 whp and 105-110 mph trap speeds.. The second will get you 280-330 whp, a more fun powerband, and probably with 105-112ish trap speeds. I have run the gamut from this to that and everything in between in terms of stock block setups. These are my two scenarios I would actually pursue. The first costs about $3000, the second costs about $3500. With 850s starting to show up used in good shape for $1500-2500, there's no reason we don't see more of us actually going fast :)

3" MAF That probably really throws off the ECU's load calculations. Sorry to jab at you for the stock-ness, but with your knowledge you should at least have a damn boost controller on that thing If I ever see you and your car in real life, I'll sneak the windshield washer vacuum tee into the wastegate line for ya ;)

You have stock exhaust, boost, and turbo I am not surprised to see you never get to 100%.

Also, I would be interested to see what happens to the logged ignition timing at 1.2 bar, 1,4 bar, etc. If you have more timing at lower boost levels, it is pulling it because of knock detection, whether it be erroneous detection or not.

Can you log throttle position? I find it difficult to believe that timing was retarded all the way to 0.1 degrees of advance... Have you verified the logging's values with a timing light?

I think this is a very good area to look into. The stock pumps can support decent power levels, but almost every one of mine has had some sort of issue (in 850s that is). It's an area that isn't always looked into as much as it should be.

If your compression is even, it could have to do with your gauge. I think compression tests are most useful for showing differences between cylinders. Can you check to see if your turbo has any end-end shaft play? If the compressor wheel is pulling forward under boost, then rocking back when you lift off the throttle, there could be oil getting past the hard exhaust side shaft seal when it moves. Just a guess, really not too sure if it would work like that although I seem to recall similar symptoms on one of my setups. Oil in the intercooler piping, I forget, do you have a catch can or not? It's most often just from the PCV... Also, if it was coming through the compressor housing, I think it would stick to the piping and intercooler core before ever reaching the engine itself. Given all of the hard running your engine has seen, if you're still a bit shaken up about the compression readings, you may want to do a leakdown test to check the ring sealing that way. That is a much more repeatable and reliable way of testing in my opinion..

Since it runs with the greens at 535cc/min, I would still kind of suspect the injectors. I have heard a lot of issues with Dekas. Sending them to be flowed is an alright plan, you can at least verify what they are flowing at. You may want to send the greens as well while you're at it so you can absolutely see where they are at. Then you can say with certainty that the greens at 5 bar flow "xxx cc/min" and then calculate where to put the Dekas to match that rate. If they are flowing the same effective rate but one runs right and one doesn't, it has to be an injector issue. Have you tested resistance across the injector pins on both sets of injectors? Something does not add up.

Misfires can very well cause the lean readings though, on the bright side. So as long as it was spiking lean while misfiring, the AFRs may well settle once you resolve the misfires. Then you'd be in business again :)