Hi jp335i
Yeah! You have been busy. I love the way you documented all this. Few few people do that and it's great to see
I'll throw my 2 bits in. First a few comments with regards to your mods:
Correction factor-- Can you post up STD correction? It seems to be the standard on this forum. Nothing is wrong with SAE but we should compare apples to apples. All the power numbers will go up a bit. Even the stock run.
Catted Downpipes-- I'm still not sure how much power these are worth over the stock catted downpipes. Certainly nothing like going catless. Without having tested them, I'd be surprised if they were worth more than 5-10whp. Then again, my catless downpipes really weren't much more than that until I tuned the map accordingly. And then they picked up 25whp peak and nearly 70whp at redline! I wouldn't expect that with catted downpipes but it is certainly something we want to (and will) test out ourselves.
Meth/water injection-- Coming from the EVO world, this is something that I have a lot of experience with. Just not in BMW applications yet. But in EVOs, meth/water mixes only really helped with power when we ran a lot more meth than water (like 75/25). And it REALLY helped when we ran straight meth. Of course, all this specific tuning as just injecting it will make it run a lot richer. To take advantage of this injection, you'd have to adjust the AFR target as well as add some advance. This is especially the case if you have any water in your injection mixture because its presence is actually contributing to power loss (but meth to power gain). On the dyno, you will see some improvements in run to run consistency by virtue of its cooling effects. But, on a dyno, we are barely cooling the car anyway because even a big intercooler fan doesn't replicate the kind of cooling effects you'd get on the road at even just 30mph, let alone 70mph. Still, meth/water injection is something that we will eventually play with. The good thing about your particular approach is that you are using it for a cooling agent, not necessarily a power adder. This is safe just in case you get a plugged jet or any other injection system failure.
Intercooler-- Again, this is another product that we will be testing. In my experience, power gains afforded by intercoolers can be a little misleading. Not intentionally but just by the nature of dyno tuning. This goes back to the whole inadequate cooling issues that we see on dynos. Without real 60+mph winds going through the IC, an IC will not operate at peak efficiency. This means that it will not properly transfer heat from the intake charge to the fins, to the ambient air. But not all is lost, even without adequate airflow, the intercooler still has mass. And the heavier it is, the more heat it can steal from the intake charge. In some cases (where airflow is low enough), the stock intercooler will operate at just 50% cooling efficiency (as opposed to the usual 80+% it operates in on the road). Whereas a bigger (ie, heavier) IC will still operate at an effective 80% just do to its greater thermal mass. On the dyno, in this case, you will see a huge power differential, esp at high RPM where the heat rejection differential is huge. Of course, without enough airflow, all this cooling ability is temporary. Once either IC absorbs as much heat as it can (through poor airflow and limited cooldown time, it becomes "heat soaked" at which point you are relying completely upon the ability of the core to shed heat from the charge. So what we sometimes end up seeing are 'unfair' dyno tests between a stock intercooler and an upgraded one. Yes, the upgraded one made more power on the dyno where it enjoyed its extra thermal mass. But, on the road, with proper airflow, this advantage doesn't exist. At which point, you are relying on its better efficiency and reduced pressure drop. Which can be substantial in some cases. I'm just not sure that is the case in the BMW when we are only talking 400-450bhp and a pretty large, well-designed stock intercooler to begin with. But again, we will see soon enough. It's just hard to keep up with you guys while giving every level of upgrade a fair shot!
Boost Level/Taper-- It's perfectly normal to see lower boost pressure with the presence of additional cooling mods. The intercooler, itself, will reduce the boost target if it cools the charge better. Same with the water/meth injection. Especially if it is sprayed upstream of the TMAP sensor. The cooler the air charge, the lower the boost. Of course, one can run more boost when the air charge is cooler (since the engine is less knock prone). But we are dealing with a fuel system limitation right around the 400whp level. It's not an issue when we are running race gas (since the extra octane allows us to run leaner). But on pump gas, I wanted to make sure no one runs into this by accident. This is another reason that taper is in there. Yes, you can get rid of a lot of it by ramping the user TQ values, at higher rpm, upwards. But please do not do this until we have additional safety measures in there. At this point, to play it safe, the max power I'd like to see anyone make on straight pump gas (with no additional meth injection) is 380whp. On race gas, I'd like to stay under 410whp. Both are 10-20whp shy from what I consider to be the fuel system limitation. At least what I saw on my car. I'd like to custom tune a few cars just to be sure. This will happen in time.
Conclusions--- You're runs look great! It's a bit too early to have maps specifically made for your level of mods right now. But I'm happy that you are able to run the baseline map with no real issues. The little torque bump you get at 3800rpm is typical given all your free-flow mods. That will be gone with a mod specific map. For the time being, you can get rid of it by just dropping the User Tq value at 3500rpm by 3-4%.
Cheers and great job!
Shiv
