300SD race car

[buzzboy]

This is my '79 300SD LeMons car.
We bought the car last spring for 800$ with a good running engine, bad paint and a dilapidated interior with no working vacuum accessories. For the first race we repainted it(to fit the theme of our car), stripped the interior, removed bumpers, caged and added racing safety gear.


For the second race we cut 1.5 coils from the front, 2 coils from the rear, removed the stock air cleaner and straight piped the exhaust. We're still not fast but she handles much better than the first time around.


We're hoping to figure out how to make her quicker and handle better for our next race, sort of an ever-evolving racing machine. Our main gripe is how slow she is compared to other cars. During our last race our hot-lap was 30 seconds off the fastest car. We'd like to cut 5 seconds off our lap times and possibly be able to pass somebody. I don't know enough about the om617 to know how much more I could get out of it. I do know though that I'd like to move to a bit shorter rear end for some acceleration. We've also been looking for a 15" wheel that will fit on the car. We picked up a set of w201 wheels thinking that they would fit but they have way more offset than the stockers which makes the track width very narrow and gives clearance issues that won't let us run them. 

[MattW116]

Slap a massive Holset truck turbo, home brew manual boost controller, and a cheezy cheap Chinese intercooler on it! I had a buddy who did that to his 300SD, but he kept cracking transmission cases. Anyway, due to the forged nature of the OM617's internals, they can take a fair deal of abuse

Love the Planet Express/Futurama theme!

It's kind of neat to see one of these in Lemons. I have a Miata track car myself, and a W116 300SD as a daily. I know you're looking for 15's, but may I recommend the 16x7 (x7iirc) wheels that were optional on W210's? They're ugly, but allegedly some of the the lightest production 16x7's ever made. Unfortunately I'm not sure of the offset.

They look like this:
http://i198.photobucket.com/albums/aa240/moparrbust/powderedclkblackgreypairs.jpg

[ZCarFan]

I've never warmed to LeMons -- Chump Car feels less contrived without the pretense of having to be overtly silly just to take some laps.  Bet it's fun nonetheless.

How does the chassis work now that it's lowered?  I imagine it's still prone to a lot of roll, but the basic geometry should be good and you can dial in a useful amount of negative camber and still have a lot of caster.  Those 14s have got to go though.  you should be able to fit 15s from a  86-91 W126 and they are plentiful.  Should make tire selection easier.

Engine-wise my understanding is the factory plungers in the pump are simply too small to deliver any significant gains in power.  the best I've heard of was a bit over 120 hp at the wheels with the stock pump.

How many miles on the car?  I've got a 280SE with 3.69 gears and I'd entertain the idea of swapping the diff for the 3.08 in the SD.  i don't see the point of running the thing at 3300 at 70 mph.  Will be going to the Mitty again this year if you'll be there.

[buzzboy]

I need to check out those cars for wheels, it just seems hard to find them in my area and I don't want to buy a whole set to find they don't work. If I can find some 3.69's I'd be really happy. On the track we never really see 4th gear so I'm not worried about killing the overall speed.

She actually handles pretty well in the corners, especially now that we lowered it. It's not as flat as the smaller cars but still much better than our first race. Also we switched tire pressures from 30 to 48lbs and it made a huge difference in handling. Much less sidewall flex now.

[Squiggle Dog]

Oh, holy crap, that is something different! As a 300SD owner, it's really neat to see one being raced. If you check out http://www.superturbodiesel.com/ , they get quite a bit of performance out of the OM617. I don't think 500 horsepower would be out of the question with the right modifications. I've heard of these engines putting out as much as 2,000 horsepower--but only right before exploding into shrapnel.

[ZCarFan]

Oh, holy crap, that is something different! As a 300SD owner, it's really neat to see one being raced. If you check out http://www.superturbodiesel.com/ , they get quite a bit of performance out of the OM617. I don't think 500 horsepower would be out of the question with the right modifications. I've heard of these engines putting out as much as 2,000 horsepower--but only right before exploding into shrapnel.

But the point of LeMons is cheap racing, and getting power out of an OM617 is not cheap.  Those guys at superturbodiesel are spending thousands just on the pump mods.

The fundamental problem is the pump simply can't deliver fuel to make more power and nobody works on injection pumps on the cheap.  New elements alone would be far over a LeMons budget.

[Squiggle Dog]

Yeah, you gotta pay to play... or be really good at engineering, machining, and fabricating, I guess.

[buzzboy]

Yeah, we're learning about diesel mechanic work through this car. One day it might get a w56 transplanted into it, but with a sourced adapter.