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Can TD42 block be used for TB42 engine?

Posted: Mon Aug 09, 2010 7:40 pm
by toughnut
Hey guys. I've found a couple of things on this but usually no answers, just the questions. So I'm asking again.

Can a TD42 block be used for a high compression TB42 engine?

The basic specs are as follows:

TB42 (89 Model)
4.2 litre, water-cooled petrol engine.
4 cycle, 6 cylinder in-line OHV.
Crossflow cylinder head, high camshaft.
Bore x Stroke: 96 x 96mm.
Displacement: 4169 cc.
Compression Ratio: 8.3.1.
Max. Power: 125kW @ 4200r/min (DIN).
Max. Torque: 325Nm @ 2800r/min (DIN).

TD42
4.2 litre, water-cooled diesel engine.
4 cycle, 6 cylinder OHV.
Crossflow cylinder head, high camshaft.
Bore x Stroke: 96 x 96mm.
Displacement: 4169 cc.
Compression Ratio: 22.7.1.
Max. Power: 85kW @ 4000r/min (DIN).
Max. Torque: 264Nm @ 2000r/min (DIN).

So they have the same bore, stroke and displacement but I'd like to find out the size of the bearing jounals on both the rods and crank of each and are they interchangable?

Also can a TB head be used on a TD block to effectively have a petrol engine capable of high compression. (head being the weak component)

Re: Can TD42 block be used for TB42 engine?

Posted: Mon Aug 09, 2010 7:49 pm
by stimpy
you could do it side by side they are very much the same the td42 block has bigger head studs about 12mm and the tb42 has about 10mm so you would have to drill the head out. you could just put a carby on the td42 and take the glow plugs out and put spark plugs in maybe

Re: Can TD42 block be used for TB42 engine?

Posted: Mon Aug 09, 2010 7:51 pm
by toughnut
I guess the other thing to look at would be the CC size of each head and would putting the petrol head on the diesel block lower the compression enough to run petrol or is the deck height of the block too low?

Re: Can TD42 block be used for TB42 engine?

Posted: Mon Aug 09, 2010 8:55 pm
by toughnut
I didn't even think about a dizzy. Guess thats a big reason it hasn't been done. I guess now I'm just chasing the info on the various internal components to see if there is a viable way of doing some decent mods or whether its just easier to get after market H beam rods to suit.

Re: Can TD42 block be used for TB42 engine?

Posted: Mon Aug 09, 2010 9:34 pm
by toughnut
Didn't think of this before but an EDIS system could be used instead of a dizzy. More food for thought. Hmmm

Re: Can TD42 block be used for TB42 engine?

Posted: Thu Aug 12, 2010 6:37 am
by Raisins78
Why would you want to? i dont get it? the petrol has more than enough potential for big hp, or convert to the diesel (your talking changing blocks anyway) a few mods on a standard 4.2td will give plenty of grunt.
unless your just trying to do what hasn't been done before, then bravo.........your gamer than me, considering the potential benefits of running a high comp (very high) petrol is far outwayed by drivability, reliability and effort to put it all together.
dont forget, the diesel may be good for hih compression, but how will it handle the revs of a petrol setup???