My old 300hp 4g93 needs some lovin!

Nice pics, what do you mean by Cosworth pistons? Are they for another motor?

From what I understand, they are blank pistons cast by Cosworth, then machined to your requirements by a third party. In this case, Special piston services.

Just having a break from lapping the valves.
Hopefully, the head will be back together tonight. Took the day off work tomorrow to reassemble the engine. (hope the boss isnt on this forum).

Cast or forged by Cosworth?

i didn't think any 93 was built with 93 parts. lol

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Have you checked that the volumes of each combustion chamber are even???
I also worry that the valve seat is now undercut by the detonation that bottom end looks too pretty and expensive to put a sub par head on.

Head reassembled.
Yeah, I know what your saying Frosty, but I figure its not too bad, considering my old r31 Skyline had it a lot worse than that and it still pulled 430KW on the dyno with 2 chambers ground out and 2 different types of pistons. Im dropping the rev limit to 6800 and crossing both my fingers, so it should be ok.
What could possibly go wrong.............


Dont answer that.......
Anyone.......

Sorry Spetz. SPS told me they were forged pistons.
And speaking of 93 parts, I was also told it was stroked to 2 litres, but the casting in the crank says g93, so Im assuming its still 1.8.

94 crank?
is the 94 block taller than the 93?
If so would need short rods...

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You could easily measure the stroke.
I believe it was 89mm for the 4G93 and 95mm for the 4G94 if I am not mistaken

We are at 89mm folks. And 81.5mm bore.

1.8

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I don't think that's necessarily a bad thing. The 4G94 bore/stroke ratio was really undersquare

1.8 is not bad, but being told it's a 2.0 is when it is not.

the 1.8 could probably make more power anyway in fact the 1.6 is probably better again.

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The 1.8 has (like most Mitsubishi 4 cylinder motors) a pretty bad R/S ratio at around 1.51 or so.
Using the 1.8 crank in the 2.0 block and longer rods would be pretty good for revs and hence power

So......
A bit of an update.
I got the engine back together on Friday night. Kicked it over about 1 am. It sounded better than I have ever heard it.
Took it for a short run, changing the revs and load constantly to help bed in the rings.
Made it approx 700 metres and put my foot on the clutch approaching an intersection, and it stalled. Tried to turn it over and starter motor sounds like its not working.
I knew straight away it was not the starter motor. Sure enough, engine locked up.
Walked home got another car, towed it back and pulled the rocker cover off, white smoke everywhere.
Long story short, what are called the rocker beams can be installed upside down which means no oil will pass through these hollow beams and supply oil to the cam journals via pinholes.
Now, I think there may have been a pre-existing condition, as the cam did bind slightly when you rotated it by hand.
However, that does not excuse Captain Numpty here from ballsing it up completely.
I have managed to extract the cam from the head and it is ok. The head is rooted, but I think it was doomed anyway.
I have another stock head, so now its time to port.

Photos are of No 1 Journal



Anyway, this is Captain Nupty from:

Never Be the Same Again Racing..........

Looks pretty bad, will you do the porting yourself?

you'll get there, bigger and better.

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Strip the other head and use it as a guide for the new head. There are some good videoes on the YouTube's.

Yes, Ive ported and port matched heads/manifolds before. Its been a long time, but slow and steady, Ill get there.
Its pretty much turned into a complete rebuild and I am actually quite enjoying getting back into it. Pulling out tools I have not used in 10+ years.
Dont want to over do it as I still believe a bit of turbulence is good for atomising fuel.
Im actually glad it happened like it did as if it happened under any load or revs it could have been catastrophic to the bottom end.

I was at WSID or Sydney Dragway on Sat where my nephew invited me to watch him work with his mate on his VB Commodore at a private session. Car ended up running a 6.13 @ 239mph. The engine tuner that came over from the states said its the fastest time he has ever seen in the world for a 4 door tin top.
This pic is my nephew doing the valve clearances after a run.
Its unreal, about 3 hours of 4 blokes working on the car flat out just to get it ready for the next 6 seconds!
The guy that owned and drove the car, Jeramy, was disapointed the car didnt get into the 5s.



Anyway, the point is, where do you stop and say enough is enough.

I thought I could hear noise coming from WSID on Saturday.