McBear

I have a 88 300SEL with 200+K miles. The body, suspension and everything else is perfect. Drivetrain is the weakness. I want to look at bumping that up. Everything I can tell points to putting in a very late model LS1 with 6 sp and a 560SEL rearend to make very good strong HP, 30+mpg for road cruising and near limitless mods for the future.

I know the purist argument of putting a GM motor in a Benz but the 350 motor is one of the strongest motors ever developed. And if you gotta stay pure you have to throw away Cobras, Panteras, Masarati's, Cunninghams, Nobles, Lotus, etc.

Anyone done, know who does it?

C43AMG

What's the matter with the current motor? I thought those 6 cylinder motors are supposed to run forever.

McBear

They run forever, just not all that quick and the tranny is starting to go. I have a 300E that can use the top end of the motor and that would allow me to play with the SEL which has plenty of room to put in a larger motor. The 300E just does not have that much wiggle room. Otherwise I would be looking at asking about an LS1 in a 300E Sportline.

C43AMG

I am currently looking at - # 1 1990 300sel w/150k and 91 420sel w/150k.Based upon your experience, which motor/drivetrain is better.FWIT the 91 is $1k cheaper. Thanx in advance.

McBear

Maintenance on the 300 will be less due to 6 cyl obviously. Both motors are very very good. The 420 is stronger and I believer has a stronger tranny but all the stories say to get the tranny worked on/replaced at 150 anyway. Every 80-90's Benz tranny that I know of has a 150K lifespan. Check the paperwork of the cars and see what has been done. Topend will want some work at 100-150K for valves on either (300 will be cheaper). Replace timing chain at that time. 300 will be about $2500. Otherwise both cars are monsters. I have lowered my SEL with the same suspension that my 300E Sportline has...Which is the 500E suspension of bigger front/rear sways, shorter springs (HR) Sport Bilsteins, better bushings, tighter steering rack, etc.

The 300 has 3.46 rear end to make up for 177HP on starts, the 420 and 560 have 2.47 which makes the motor a bit quieter on the road. The lower diff on the 300 negates any fuel savings you would expect. I have been told not to try and put a 560 diff in for fuel savings as it would be very slow out of the hole.

My thought is to put a large lightweight motor (LS1 is lighter than any of the Benz motors of the era) with either 6sp ZF manual or auto tranny from Vette which is very smooth and use the rear diff from a 560 which will hold the power. That would give me options to map a LS1 ECU which is available in a million variations, potential for very cheap turbo or supercharging and replacement parts, if necessary anywhere. I have had LS1's in my trucks for company use and heavy towing (work and race cars) and have never had a failure in 600K miles. Initial expections are 400bhp and 30+mpg in initial tuning with a 6sp which will have the car cruising at 1800rpm at 80 or so.

C43AMG

Thanx for the info.One more question , what kind of MPG are you getting with the 6 cylinder ?

McBear

20-23 on the road. 17 or so in town. I don't drive that car hard so few hard starts

McBear

Only other option seems to be to either supercharge or turbo the 300 motor. Anyone done that to the 103.xxx motor? Opinions?

newton22

LS1 is a awesome motor.



Went into a E30 BMW. I've also seen some squeezed into a Miata.

HLG600

LS1 in a E30? That should make a very interesting ride.

K_Sport Driver

why not swap in some reliability and power? put in the 2JZGTE motor. those will last forever and can create more than 1000bhp

McBear

If I were putting it in my 240Z that would be one thing but I really don't see a need for that type of motor in a sedan. 400-500 is more than enough hp. Also, there is not a more reliable motor, or easier to maintain motor than the small block GM motor. There are more of the on the road than any other motor in existance and I can get parts anywhere at anytime. My last 350 (327) motor ran 350000 miles without a rebuild in a 65 Corvette and was only rebuilt then when I rebuilt the entire car to get ready to sell.

psycho's poetry

Plus you have to tak into consideration, the size of 2JZ-GTE. Inline engines are naturally better that v-oriented engines in many ways: higher rpm, more starting torque, better balance, durabilty, simpler exhaust layout etc. but, they do have one big problem; engine bay space. You can easily fit a v8 and sometimes squeeze in a small dicplacement v12 in the same space an inline-6 fits in. You ever notice how long the Supra's engine bay is. That is why they probably fit the LS1 in the bmw(if I'm not mistaken aren't BMWs almost always inline-6's?)

HLG600

Any performance figures?

GTA23109a

Swapping a LS1 into ANYTHING is never a bad idea . . . . The availability of those motors coupled with their light weight and HUGE aftermarket support make them the easy choice for nearly ANY hotrod project. 30mpg doesn't hurt either.

McBear

Well, a solution has been decided. Last week a New Old Stock Mosselman Twin Turbo for the M103 motor came available and I grabbed it up. It will provide a bump from 177hp to about 310hp (reliable with only 5lb boost). This will allow me to change my rear diff from the current gas sucking 3.46 to a more friendly 2.47 and give me a very strong bottom end with a strong power band from 1200 up. Installation will start as soon as I beef up the transmission and driveshaft.

Good part about the setup with <6lb of boost is that I don't need to rebuild the bottom of the motor with lower compression.