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      03-10-2012, 08:51 PM   #1
Carl Morris
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Stock 335XI 6MT + Cobb + some E85 at high elevation

So I picked up a used Cobb AP today. Updated the AP itself to the latest Beta, cleaned off the old maps and logs, and loaded up the various Stage 1 beta maps that just came out. Car is otherwise bone stock. Previous car was a GVR4 with an EVO turbo that ran 12.9@105 at Bandimere on 91 octane at 18psi. Faster with better fuel.

Loaded the Stage 1 sport.
I've been reading the board a lot over the last month and was expecting a strong torque peak when boost came on, but fading quickly at higher rpms.

My first impression was that the fade out wasn't as bad as I thought, but mostly because the torque peak wasn't as big as I thought it would be. I could feel the difference, but not quite what I'd expected from the rave reviews. Perhaps I'm jaded.

Drove it around a bit, trying to see if my impressions changed. Occasionally it would feel pretty good at part throttle, and 4k+ was decent, but I really expected more from 3-4k.

I have a lot of experience with E85 mixes and what you get from them on a 4g63, and I've read about people's experiences with the N54, so I decide to try something new...

Add three gallons of E85, top off with 91, load Stage 1+FMIC aggressive.

I know, I know...shouldn't do that without actually having an upgraded FMIC, but for short bursts I'm comfortable with using it on an E85 mix.

No misses or codes, runs a lot more like what I was originally expecting. Feels more like a turbo car instead of an 87 Mustang 5.0 :-). I'll do some logging of knock and timing parameters to look for any signs of trouble, but I'm not feeling any problems. Basically happy.


Question: Should top end still feel kind of weak relative to the midrange?


My Mitsubishi was turbo limited but still definitely felt stronger to redline. I'm curious if anybody who has done this at Denver-ish elevations has an opinion on whether it's more about the tune or the fact that I'm still on the stock intake, FMIC, and downpipes? In other words if I did the same thing with a Procede or JB4 would I be much more impressed with the top end, or would I have to change some hardware before being impressed no matter what tune I use?

In either case I'm going to stick with what I've got for now for warranty/convenience reasons, but I will put a real FMIC on relatively soon. The plan is then to just drive it that way until the big single turbo stuff sorts itself out and the CPO warranty is closer to being done.
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      03-10-2012, 09:23 PM   #2
forza1976
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hey, side question... what color is your 335?
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      03-10-2012, 09:37 PM   #3
Carl Morris
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It's white with the sport package + 18" 162s. Bought it at the end of January at Gebhardt in Boulder.
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      03-10-2012, 10:09 PM   #4
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I didn't know you could run an e85 on an n54....it is my understanding that after 6000rpm, the power will start to decrease no matter what tune you have. I can't say much about the Cobb though. However, in comparison between my old jb3 and my current tune (procede), the top end of my current tune is much better.
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Best 1/4 time = 13.6 @ 106.6 (with JB3) at Bandimere Speedway (5800' above sea level)
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      03-10-2012, 10:46 PM   #5
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Quote:
Originally Posted by Carl Morris View Post
It's white with the sport package + 18" 162s. Bought it at the end of January at Gebhardt in Boulder.
I had my eyes on that one. It seemed to sell fast.
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      03-11-2012, 12:25 AM   #6
Carl Morris
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I'd been looking for that exact combination for about a year nationwide. Almost bought silver ones in Missouri and Boston but they weren't exactly what I wanted so I didn't want to travel that far. When I stumbled onto that one at Gebhardt and they didn't want an unreasonable amount I had to jump on it. It had been misadvertised as a 6AT and I just wanted to show my wife a few features on it...I had no intention of buying that day.
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      03-11-2012, 12:26 AM   #7
Carl Morris
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Regarding E85 people seem to be running a 50/50 mix without issues, but I have no desire to run that much. I'm good with about 20%. With my Mitsubishi that was enough to max out the Evo turbo and run plenty of timing while doing it. It's amazing stuff, IMO.
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      03-12-2012, 02:30 PM   #8
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20% E85 mix should have no harm to anything, just wouldn't run it full strength like you said. E85 is about 105 octane at the high end, so it should give some performance boost, especially when tuned (just like race gas). Personally I would never use E85, and would just go with race gas when needed.

And yes, with the N54 on stock turbos, especially at our altitude, your top end will feel weaker than the midrange....the small turbos just simply run out of breath. But what makes them fall off at the top end is also the reason they have near instant spool.
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      03-12-2012, 02:45 PM   #9
Carl Morris
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It seems to be working nicely so far. I plan to have a FMIC on before the weather gets hot, though.

Speaking of instant boost, I'm confused about the boost curve...I can't tell if it's the Cobb or something else. I would expect turbos this small to come on hard even below 3000rpm even at high elevation. What I'm seeing is tentative performance from 3-4k and then it blazes. Anybody know if the Cobb intentionally limits boost to a lower level from 3-4k, or if it's due to running lean (I'm used to open loop and lots of fuel at WOT) or why it's so tentative right where I'd expect it to be strongest?
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      03-12-2012, 06:04 PM   #10
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Should be around 2,800-3,000 full boost up here.

Can you post some of the graphs, would be curious to see.
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      03-12-2012, 06:08 PM   #11
Carl Morris
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I'm still trying to get the hang of logging on the AP. I've gone one log so far for a few seconds and it only recorded about 4 parameters. I'll try to get it figured out so that I can record everything interesting in the next day or so.
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      03-12-2012, 07:44 PM   #12
Carl Morris
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Is there a standard template that everyone uses for creating graphs from logs? I notice everybody's logs look the same. Anyway, I was able to successfully log the drive home and managed to get one 2nd gear pull over most of the useful rpm range. I logged a bunch more parameters (stuff like WG duty cycle) but only graphed the ones that seemed useful in hindsight.
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      03-12-2012, 07:47 PM   #13
Carl Morris
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It looks like full boost hit at about 3600-3700 depending on your definition. It definitely was pulling much harder 500rpm later, though. What that makes me suspicious of is the air-fuel ratio. I suspect it's making significantly better power at 12.5:1 than it is at 14:1, but I don't know that for sure.
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      03-12-2012, 11:22 PM   #14
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That boost curve looks horrible, taking way too long to build full boost. How does it compare with TPS and pedal input?

Timing seems to match up pretty well with the load. AFR's look typical for Cobb. Would take someone smarter than me to tell you what might be going on. Try posting in the N54 forum, or send to Cobb.
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      03-12-2012, 11:30 PM   #15
Carl Morris
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Thanks for looking at it. It is second gear, so of course it will get boost later than in a higher gear. The entire range of the pull was at WOT, I didn't include any data from before or after WOT. The requested numbers and actual numbers all looked good regarding pedal and TPS and everything else.

Your thoughts (and the way power falls off more than I'd expect at top end) are making me wonder if I have an airflow issue with the air filter or the cats. I just got the car and it has 57k miles now, so anything is possible. I should take a look inside the air filter box. Hopefully it's not full of leaves or something :-).
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