5.3 LM7 powered '97 BMW M3 sedan!

[BRAAP]

Thank you.

Car is at the exhaust shop currently, owner of the shop was on the fence which gen-I SBC to build for his '71 Chevelle, when he saw the LM7 in my car, he lit up like a boy on Christmas morning, he's now set on an LM7-4L60E conversion.

[tanz45]

x2. Awesome build and detail.

[socal1]

great job man...cant wait to see some video

[BRAAP]

Talked to Ryan, owner and fabricator at Mulligans custom exhaust and custom hot rods in Sandy today, he said the exhaust is done and it's a sleeper. I took that to mean it's quiet, exactly what I wanted. I gave him him free reign with the exhaust, wanting to retain as much of the stock exhaust as possible, in particular the stock M3 muffler, neck down from the 3" collectors to 2 1/2".
Stopped in and took a peek under the car, WOW! very nice work, Ryan is a craftsman, too bad his work under the car where isn't seen very often. All bends are mandrel, welds are beautiful, came out much nicer than I hoped. Ryan transitioned from the 3" collector immediately to 2 1/2", tidy quality 2 1/2" flex joints just aft of the V-band, 2 pair of O2 bungs per pipe pre cat, (one each for narrow band O2, other two for wide band tuning). The stock cats with their angled inlet was not worth working with so he installed a pair of tight tidy aftermarket 2 1/2" cats then added 2 post cat O2 bungs. I wanted this to be quiet as a daily driver so adding another muffler in line with the stock M3 muffler was on the list. As luck has it, the BMW tunnel is just wide enough and deep enough to fit a dual 2 1/2" In-Out muffler, Ryan and I both like the crisp snap and snarl of a V8 exhaust note through Spintechs. From there he continued in 2 1/2" to the stock M3 tail pipe where it necks up to just under 2 1/2" from the 2" or so.
He used the BMW carrier bearing mount holes for rubber isolated hangers.
Fabrication and installation is 1st rate, anyone in the greater Portland OR area needing custom exhaust or any custom performance fabrication work, I strongly recommend Ryan at Mulligans in Sandy. Humble, down to earth, great guy. ;-)

http://www.mulligansmuffler.com/

How does it sound? Uh.... well, it is soooo quiet there's nothing really to judge, not much of an exhaust note. Standing behind the car about 20 feet back, someone in the car revving up the engine, you can hear the intake under the closed hood, (sans filter), over the exhaust. Total sleeper. Ryan says it's too quiet. Before he tied in the stock muffler he said with just the Spintech it sounded AWESOME!

Drive home was AWESOME! car is as quiet as a stock M3 if not quieter inside.
HUGE thank you to Mike of JTR for his use of OE GM engine/trans isolators, even with these moderately firm Vette isolators that don't allow any movement by hand, it is smooth, no buzzy-ness. Best friend drove it tonight and commented on it being so quiet and smooth, the car is deceptively quick. No aural indicator or buzz to indicate the car is working hard other than the rapidly climbing speedo needle.

4 day weekend for me starting Friday, will take apart the front end to properly reassemble and working out any bugs, hope to be driving it daily starting Tuesday.

Video to come soon.

Here are some pics of the exhaust work, my apologies for the poor cel phone photo quality.

Standing under oil pan looking back;


From behind looking up;


The Spintech and hangers;


Profile;

[lechez71]

very nice! stop teasing get s a vid lol.

[BRAAP]

Maiden voyage update.

Buttoned up the front end today, took care of the Alt charge light, drove into town, filled the tank and put 30 miles on it, mix of highway and tight twisty backroads. Drove excellent, LOVE the additional torque, no added noise or buzziness, the rubber mounts keep the smooth BMW refinement, no sacrifice in performance. ;-)

Brought it back home, obligatory burnout video. You can sort of tell how quiet it truly is in the video, note how loud the hood closing is and induction noise vs exhaust noise. WOT bouncing off the rev limiter set at 6000 RPM.

http://www.youtube.com/watch?v=ZKa34tRFjDU

Yee HAAA

(How do you embed YouTube videos here)?

[screamin86]

wow i absolutely love it! more videos please

[BRAAP]

New starter is in, did a Bubba fix to get the center of the fuel tank above the tunnel roof so it wouldn't rub on the drive shaft, gave the car a quick rinse, my oldest daughter asked to drive it around the lake, and off we went. Every time she pushed on the throttle she giggled, when she tried WOT in 2nd and 3rd, giggles stopped, BIG eyes, then lots of giggling.

Lots of little stuff to finish such as PCV, air filter, mounting the GM cruise module, etc. Till the next update, a few shots after the rinse.

[BRAAP]

Put 150 more miles on it over the weekend, LOVING it. Runs and drives just like the stock M3, similar power band and same drivability but with a butt-load more torque everywhere, even with the tiny 5.3. ;-)
Hooked up the GM cruise control and it works perfect. Also hooked up the cooling fan, still have a few more loose ends to tie up such as intake plumbing, PCV, etc. taking it to work this week, 153 mile per day round trip
Love the GM cruise control, doesn't lag over hills and responds crisply to accel/decel inputs. Another attribute of GM cruise strategy that I really like is each click of accel or decel raises or lowers your speed by exactly 1 MPH per click, 5 quick clicks adds or subtracts 5 MPH even if coming down a hill and it takes several seconds to coast down, it gives you what you asked for, not just a momentary switch you hold till you reach the desired speed.

[BRAAP]

Wife says AC is a must, condenser is on the way and if my M compressor wont fit will be sourcing a compressor.

MPG update. 90% freeway, 65-70 MPH, 10% city, tight mountain backroads, (2nd gear), handful of WOT blasts to 90-115, PCM with mix & match maps and settings, LTFT showing 10-20% compensation, achieved 26.7 MPG. I am quite pleased with that considering. With a bit of tuning I think 28-29 MPG under the same conditions is a reality.