Author Topic: Souping up a 250 engine. (Read 16442 times)

mirkwood · « **on:** March 26, 2012, 05:47:17 »

OK, the plan as outlined to me by the owner is to rebore and midly soup up his engine.
I suggeswted EFi and EDIS igniton so we can map the whole cycle and release a few hidden horses without going overboard with the dollars.
First plan is to strip and check the engine for wear ,thats normal.
What is planned though ,is because this is in fact a 250S sedan engine with dual Zenith carbs

i suggested we bolt in a manifold from a SE engine modified to accept electronic injectors . it also occured to me that I could bolt on a SE head with the injector holes bored out to fit the EFi parts. Finding a useable head is the problem.
Cam will be a SL grind to keep it on the boil but still driveable.
The owner wants to dispense with the water cooled oil heat exchanger and fit a alloy unit to the front.
Anyone else tried this yet ?

Cees Klumper · « **Reply #1 on:** March 26, 2012, 17:27:24 »

Very unlikely! But it sounds interesting, keep us posted please.

franjo_66 · « **Reply #2 on:** March 26, 2012, 21:16:43 »

Have a look at the following site - http://www.mbgrand600.com/

Karl Middlehauve has fitted modern EFI systems onto various Mercedes models including W113s, W108s, etc.

Definitely a very interesting project. Let us know how it comes along

Regards
Franjo

GGR · « **Reply #3 on:** March 28, 2012, 01:40:29 »

EFI will allow to make an aggressive cam grind more driveable. Higher compression also makes more aggressive grinds work better.

Honestly, the easiest would be to source a D-jet M110. D-jet is super easy to convert to Megasquirt, as all the hardware is already in place. I believe the price of the engine will easily be covered by the savings made by not having to adapt the 250 to Megasquirt. A well sorted programmable fuel & spark system can yield up to 15% additional power. That would put the M110 around 220hp.

I'm wonderig if some W114 250 were fitted with D-jet? if yes this may be the way to go, as the engine would look more original. Bore it to 2800cc as nothing replaces displacement for power and driveability on road cars.

GGR · « **Reply #4 on:** March 28, 2012, 02:09:40 »

Well, 250 D-jet do exist :

http://www.lichtenberg-classics.ie/1970merc250ce.htm#

That's what you would need to source.

mirkwood · « **Reply #5 on:** March 28, 2012, 02:34:43 »

Thats the first Djet 250 i have ever seen .

i have a 280SL head which will work ,and the same sort of manifold as in the picture I think that fitting the EFi will be somewhat simpler. The option of fitting another engine is out as the owners wants to keep the original block... but can a 250 block go to 280 size? .

GGR · « **Reply #6 on:** March 28, 2012, 23:28:52 »

Try to compare part numbers. If the MFI heads are the same as the 250 D-jet ones, you're in good shape. Manifold may also be the same as MFI ones. TB also, with a bit of luck. That would make your life easier as you could source the D-jet hardware and plumbing anywhere in the world with reasonable shipping costs.

Benz Dr. · « **Reply #7 on:** March 29, 2012, 15:24:06 »

I have a 250CE with D-jet injection. A 250C coupe is somewhat common in Norh America but the 250CE isn't.

Great running engine in a rusty car. I saved the car for the engine and kept it inside so it would be ready for the right project to come along. Maybe it's you.

mirkwood · « **Reply #8 on:** March 30, 2012, 03:17:05 »

it would be interesting get but is too far from me in Australia.

Pulled the engine down today and it has been rebuilt in the past,with a sleeve in number 1 ,a 050 oversize rebore and 010 crank grind .Everything is in good conditon exept for number three, It's 1mm down at TDC. The rod is bent,i dont know how that happened but it would appear that the bent rod was installed when the engine was rebuilt.

Benz Dr. · « **Reply #9 on:** March 30, 2012, 05:26:17 »

About the only way you can bend a rod is if the engine hydro locks. I've seen it before and this one was really bent. Engine was still running when it came to me.
This was a 450SL engine so I found a used piston and connecting rod. The bottom ends on those things are just about bullet proof.

Yeah, that would be a long ways to send anything big. I did send a cylinder head to Oz last year which took about a month to get there by mail.

mirkwood · « **Reply #10 on:** March 30, 2012, 05:45:30 »

The sleeve on number 1 and the little peices knocked out of the oil pump shaft housing tell me it may have been run with a broken piston and some lazy bugger put the rod from #1 into #3 . Even looking at it,without measuring it can be seen to be bent and twisted as much as 1mm . The owner said it was sluggish.....

ja17 · « **Reply #11 on:** April 01, 2012, 04:41:34 »

Hello,

A 250S engine will not accept a head from a mechanically injected 250SE since the chain gallery area of the head are different sizes. The electronically injected 250CE head (very scarce), which Dan posts about would work on your 250S engine.....

mirkwood · « **Reply #12 on:** April 01, 2012, 07:18:56 »

Hi Joe, thats something i need to look at closely.

mirkwood · « **Reply #13 on:** April 06, 2012, 00:20:56 »

I have taken a further step by sitting a 250 head next to a MFI 280SE head. Yes the combution chmbers are slightly different and the chain case sticks out a bit . but bolt and coolant holes are in the same place.What i prose to do ,if this head is OK,is to weld a peice in the below the chain wheel on the 280 head so it blocks off the chain case ,thus making it oil tight and although it will stick out slightly it should work perfectly OK.

Riverstick · « **Reply #14 on:** September 05, 2013, 23:51:39 »

How did the 280SE head work out for you Mirkwood?

Benz Dr. · « **Reply #15 on:** September 06, 2013, 04:23:36 »

You would think that the oil cooler on a 250S/SE wouldn't do that much but they in fact do more than you might think. I did some readings on my car once and the oil temps were about 30 degrees cooler after going through this little heat exchanger.

Some things are doable and some things aren't. Mods often end up being more feel good than feel the good.

mirkwood · « **Reply #16 on:** September 06, 2013, 09:19:10 »

unfortunately the project has stalled because the owner of the engine has been AWOF (absent without funds)

. The next step was to have been boring out the injector ports to fit electronic injectors, then making a wheel to act as a timing pickup. This would be a simple 36 tooth wheel which would mount behind the damper on the front of the crankshaft.
So...until (or If ) the owner shows up thats as far asm I will go with it. $:-\$

Benz Dr. · « **Reply #17 on:** September 06, 2013, 13:47:16 »

AWF? Never heard of such a thing as that.

Are you sure it's not the mechanic?

mirkwood · « **Reply #18 on:** September 06, 2013, 21:30:34 »

Nope,nothing to do with me,except a lack of funds coming from the owner ...I live on food etc not promises..

Besides i am in the middle of at least 10 vintage mercedes restos including a 3-0-0 B with a few engine modes such as a gull wing cam ,high compression pistons,300SE crank high vlume oil pump and so on...
https://www.youtube.com/watch?v=ZGfl1I0klpQ

Garry · « **Reply #19 on:** September 06, 2013, 21:37:19 »

Mercmad,

Just on another tangent for a moment, have you heard anything from Geoff (treedoc), thought you may know him coming from Qld also? He has gone MIA

Garry

mirkwood · « **Reply #20 on:** September 07, 2013, 02:36:28 »

I last spoke with a about 3 mionths ago, He was packing up his LHD pagoda and shipping it to switzerland where he has a house. I built the new engine for that car and he was asking me if I knew anyone who wanted the old engne,which was a 280SE engine,not a pagoda version.

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Author Topic: Souping up a 250 engine. (Read 16442 times)

mirkwood

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Riverstick

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