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+--- Thread: OM603 Super Stroker? (/showthread.php?tid=6024)
OM603 Super Stroker? - Hexafluoride - 12-02-2014
Has anybody made a hybrid om603.961/97x, with a 3.0L block and a 3.5L crank and rods? This would make a 3.3L engine with a 87x92.4mm bore stroke. The wiki article on the om603 suggests that the 3.5L engine's shortcomings are a result of the bore, not the stroke. This combo would possibly mitigate the 3.5L's problems while providing more displacement and better lower end torque, though at the cost of peak rpms. Has this been done? Is it feasible or practical?
RE: OM603 Super Stroker? - Duncansport - 12-02-2014
There has been a lot of work/ research on this for the M104 gas engine (they use the 603 3.5 crank to build the 3.6 M104 storker). I think the issue becomes the piston pin height. I think it would be interesting to try. But as with most things i do not think that much effort would reward you very much.
RE: OM603 Super Stroker? - Edian727 - 12-02-2014
i believe the 3.5l problem was in the stroke to rod ratio, witch was like 1.5 and normal is usually like 1.8. the shorter the ratio the more side to side force that will be applied in to the piston and cylinder bore. this causes the bore to go out of round. that's my understanding of the issue.
RE: OM603 Super Stroker? - Petar - 12-02-2014
God knows what is the problem since in Europe we have OM601 in 2.3 liter form and OM602 in 2.9 liter form. These have the same bore and stroke, 89mmx92.4mm , as the OM603 3.5 engine and they have proven reliable. Vans with these engines are just as reliable as older OM616 and 617 engined vans. There are quite a bit of 603's 3.5 in the W140 here and they can also do a lot of miles without rebuild. They do have head gasket problems though.
The problem seems to be limited to US market OM603 3.5's.
The gains from increasing the displacement will be minimal compared to what you can do with a bit more boost and fuel. IMHO it's not worth the hassle.
RE: OM603 Super Stroker? - barrote - 12-02-2014
hy there,
well i intend to install a 612 crankshaft, 604 2.2 pistons in a 605.961 block, at the moment the main issue pending is a 2mm shorter com rod.
wich gains dont know!! will it ever work well!!! my deal is rebuild a 605.961 out of spare and not so well pieces laying around.
regards and good luck
RE: OM603 Super Stroker? - Hexafluoride - 12-02-2014
From my understanding, the performance gains wouldn't be solely from the marginal 0.3L increase in displacement, though that can't be neglected. Rather the biggest benefit would be from the increased stroke which would manifest in increased torque and help get the two ton beast off the line a little faster. Efficiency is a little better too, I guess.
Duncan, is the piston pin height a possible obstacle with the om603 or is that just a m104 issue? Any idea if the 3.5L's rods will mate with a 3.0L's pistons without issue?
Barrote, that's a fantastic project you've got going there. How do you plan to solve the short connecting rod issue?
RE: OM603 Super Stroker? - Duncansport - 12-03-2014
(12-02-2014, 02:42 PM)Hexafluoride Duncan, is the piston pin height a possible obstacle with the om603 or is that just a m104 issue? Any idea if the 3.5L's rods will mate with a 3.0L's pistons without issue?
I'm not to sure, i would think it would also be an issue with the 603's Im sure the rods would fit the pins just fine, seems like all the 60x engine the sam in that area
RE: OM603 Super Stroker? - raysorenson - 12-03-2014
How was the longer stroke accommodated? Shorter rod, taller deck or wrist pin pushed closer to the ring package?
RE: OM603 Super Stroker? - barrote - 12-03-2014
Barrote, that's a fantastic project you've got going there. How do you plan to solve the short connecting rod issue?
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well if my guess is right the 604 2.2 rod or the 601 2.3 rod will fit, the thing is i´m still searching for them , not easy to find in second hand.
611,12,13, or maybe the 46,47,48ths may be usable, the thing is there are no rods like those in the 60X turbo series.
if i cant find the correct rod, i´ll go after the cutting of piston crown enough to acomodate the valves.
or a thick head gasket made out of aluminium, with rings of thin to seal the chanbers. something i´ve seen in a very old caterpillar.
(layered metal gaskets , is not the only way to seal the head)
regards.
RE: OM603 Super Stroker? - raysorenson - 12-03-2014
603.96 rod length=149mm, 603.97 rod length=145.
Longer stroke+shorter rod=high thrust loads, higher piston speeds at TDC. Not the best thing ever.
RE: OM603 Super Stroker? - F.R.A.S - 12-03-2014
CDI-engines have 30mm piston pin. IDI-turbo-engines 28mm. N/a-engines 26mm.
2.3-turbo is a good option. Should work.
RE: OM603 Super Stroker? - barrote - 12-04-2014
fras,
how much can i cut in cylinder Wall to acomodate a wider piston, is it safe to cut from 87 to 89mm.
or watever the 2.3 piston is.
i´m after the com rods and pistons from that engine , the thing is they are scarse.
regards.
RE: OM603 Super Stroker? - F.R.A.S - 12-04-2014
2.3L OM601 (MB Vito and other commercial applications) is 89mm bore x 92.5mm stroke.
No problem doing 89mm
RE: OM603 Super Stroker? - Petar - 12-04-2014
(12-04-2014, 01:45 PM)barrote fras,
how much can i cut in cylinder Wall to acomodate a wider piston, is it safe to cut from 87 to 89mm.
or watever the 2.3 piston is.
i´m after the com rods and pistons from that engine , the thing is they are scarse.
regards.
I don't think the 2 valve piston will fit the 4 valve head, the pistons would hit the valves since there are only 2 cut outs.
RE: OM603 Super Stroker? - F.R.A.S - 12-05-2014
2.3 om601 turbo rods and make a new bushing for the small end of the rod down to 26mm and use stock om604 89mm pistons.
But that hustle to gain 0.1-liter
It's just not worth it.