W126 420 SEL Race car, What mods good?
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MBWorld Fanatic!
Joined: Jun 2003
Posts: 1,179
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W126 420 SEL Race car, What mods good?
hey guys. I found a few W126 SEL's for super cheap and i want a beater car that I can go fast in but also have alittle fun in, most cars in the $1000-1500 range are slow as crap but the 420 is the only V8 with substantial HP that would be fun to drive. I found a local one for $1500, i plan to bargain off alittle more.
Ok, heres my plans.
Strip weight :
trunk mats, spare, jack, tools,
Rear seat, maybe rear door panels, take out from seats and put in some recaroes or someting. maybe even carpeting. I really dont care about resale b/c car is so cheap anyways. My goal it to take off a good 400lbs (from 3900 to 3500), more if possible.
Suspension: Regular H&R race springs or anything cheaper most probably.
Intake: this im confused about, i heard all cars past 1985 are fuel injected but it appears to look like a carburated motor. or is it just one of those Mercedes airboxes that looks like that (like on new ML's and etc). if i can take the whole thing off and run custom intake, that would be nice. BIG K&N of course and find out how to run a ram air system of some sort.
Exhaust: I plan to take off full exhaust system and run custom piping, No cats, I will probably run Remus universal exhaust but thats it. are there any headers for V8 W126's (420 especially)?
anyone have any stock dyno's of W126 420? anyone ever modded one?
any ideas are appreciated, thanks
Ok, heres my plans.
Strip weight :
trunk mats, spare, jack, tools,
Rear seat, maybe rear door panels, take out from seats and put in some recaroes or someting. maybe even carpeting. I really dont care about resale b/c car is so cheap anyways. My goal it to take off a good 400lbs (from 3900 to 3500), more if possible.
Suspension: Regular H&R race springs or anything cheaper most probably.
Intake: this im confused about, i heard all cars past 1985 are fuel injected but it appears to look like a carburated motor. or is it just one of those Mercedes airboxes that looks like that (like on new ML's and etc). if i can take the whole thing off and run custom intake, that would be nice. BIG K&N of course and find out how to run a ram air system of some sort.
Exhaust: I plan to take off full exhaust system and run custom piping, No cats, I will probably run Remus universal exhaust but thats it. are there any headers for V8 W126's (420 especially)?
anyone have any stock dyno's of W126 420? anyone ever modded one?
any ideas are appreciated, thanks
MBWorld Fanatic!
Joined: Jun 2003
Posts: 1,054
Likes: 1
From: Nashville
300SEL
The 4.2L M116 V8 had 201hp from the factory and 228lb ft of torque.
All US market w126s had fuel injection, in fact, the only carbureted w126 was the 280S and that was a six cylinder available from 79-85 I believe.
Funny you should mention removing the interior, I just did that last weekend! However, to clean the carpets and such, not to strip it of weight.
All US market w126s had fuel injection, in fact, the only carbureted w126 was the 280S and that was a six cylinder available from 79-85 I believe.
Funny you should mention removing the interior, I just did that last weekend! However, to clean the carpets and such, not to strip it of weight.
Newbie
Joined: Dec 2003
Posts: 13
Likes: 0
From: SF Bay Area, CA, USA
'86 560SEL
You realize that this is totally impractical, right? 
The W126s were far too big and heavy to be suitable race cars in most cases. I drive a 560SEL... Sure, it's faster to 100MPH than a Mustang GT, but it couldn't outhandle the Ford if it's life depended on it.
However, if you still want to do it, my suggestions would be:
-Loose all the interior panels (incl. headliner, trunk lining & package tray)
-Remove the glass windows & windshield, replace with polycarbonate (lexan)
-fix side windows in place & remove the window motors
-Remove all the seats except driver's, replace with a recaro & 5 point harness
-Get rid of all the "luxury" stuff: the entire HVAC system needs to go, including the heater core, blower motor, ac compressor, etc.
-Take the dash out; put gauges in an aluminum sheet (a la NASCAR)
-Take out the center console
-Take out the gas tank, replace with fuel cell.
-Re-route cold air intake system ducting to holes left by headlights
There's probably some other stuff I've forgotten, but I'd start with that.
Oh, and by the way... the 420 is too slow to race; you really should swap the 4.2L for a 5.0L & 5 speed out of a W140; either way, get rid of the entire exhaust system, and if you keep the 4.2, replace the manifolds with euro spec ones.
The W126s were far too big and heavy to be suitable race cars in most cases. I drive a 560SEL... Sure, it's faster to 100MPH than a Mustang GT, but it couldn't outhandle the Ford if it's life depended on it.
However, if you still want to do it, my suggestions would be:
-Loose all the interior panels (incl. headliner, trunk lining & package tray)
-Remove the glass windows & windshield, replace with polycarbonate (lexan)
-fix side windows in place & remove the window motors
-Remove all the seats except driver's, replace with a recaro & 5 point harness
-Get rid of all the "luxury" stuff: the entire HVAC system needs to go, including the heater core, blower motor, ac compressor, etc.
-Take the dash out; put gauges in an aluminum sheet (a la NASCAR)
-Take out the center console
-Take out the gas tank, replace with fuel cell.
-Re-route cold air intake system ducting to holes left by headlights
There's probably some other stuff I've forgotten, but I'd start with that.
Oh, and by the way... the 420 is too slow to race; you really should swap the 4.2L for a 5.0L & 5 speed out of a W140; either way, get rid of the entire exhaust system, and if you keep the 4.2, replace the manifolds with euro spec ones.
Member
Joined: Jul 2003
Posts: 197
Likes: 0
1990 560 SEC (modified), SLK55, CLK500
If you are serious, try for a 500 or 560. Not a big price difference, but a superior block.
The most important thing is actually to improve the weight balance of the car, as most of the easily removed weight is in the middle and back of the car. Easy thing to do is remove washer bottle, and move battery to back of the car.
In terms of dropping weight in order of importance:
lighter wheels
all accesorie motors
glass
smog pump
a/c
carpeting and insulation
cruise control and all linkages
weld sunroof, remove assembly
trunk padding
firewall padding
extra wiring harness
fuse box and rewire all grounds to closest point
airbags if any
steering wheel can be replaced for lighter
no need for shift knob with an automatic anyway
keep all fluids at minimum (tranny, motor, gasoline, hydraulic)
someone suggested to sand off the paint too...
anyway, if you are looking for serious answers, go to benzworld.org/forums.
Edward
The most important thing is actually to improve the weight balance of the car, as most of the easily removed weight is in the middle and back of the car. Easy thing to do is remove washer bottle, and move battery to back of the car.
In terms of dropping weight in order of importance:
lighter wheels
all accesorie motors
glass
smog pump
a/c
carpeting and insulation
cruise control and all linkages
weld sunroof, remove assembly
trunk padding
firewall padding
extra wiring harness
fuse box and rewire all grounds to closest point
airbags if any
steering wheel can be replaced for lighter
no need for shift knob with an automatic anyway
keep all fluids at minimum (tranny, motor, gasoline, hydraulic)
someone suggested to sand off the paint too...
anyway, if you are looking for serious answers, go to benzworld.org/forums.
Edward
Almost a Member!
Joined: Feb 2003
Posts: 29
Likes: 0
You need to do more research into what these cars really are intended for in other countries. FIrst off realize that US models are made for US highways and tastes, meaning ridiculously slow speeds and full(heavy) eqipment. If you want a car that will run then go look for a Euro. A 500SE/SEC should be not too difficult to find, a 560 harder. The cream of the crop is an EPA exempt model with (hopefully) NO Hydro, NO climate, NO sunroof, NO power seats and NO power windows.
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Newbie
Joined: Sep 2011
Posts: 8
Likes: 0
95 e320 cabrio, 89 420 sel, 91 300e
You don't have to change much. They were ment to run fast.
I had mine on the track numerous times, not a racecar but sure spectacular. I had more looks than Corvettes and the like. I was the fastest limo on the track
I had mine on the track numerous times, not a racecar but sure spectacular. I had more looks than Corvettes and the like. I was the fastest limo on the track
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