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Rebuilt performance 3.4 DOHC motors.


chadz34

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needs dyno proof

agreed.

 

also, what are the specs on the stock cams? it lists a "custom grind" so i am curious to compare.

 

What I could find:

 

Lobe Lift (Intake) 9.398 @ 108° Crank ATDC

0.370 @ 108° Crank ATDC

 

Lobe Lift (Exhaust) 9.389 @ 115° Crank BTDC

0.370 @ 115° Crank BTDC

 

 

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  • 3 weeks later...

My motor just died. Currently sounds like a truck and has no power to speak of. I hate to think what it looks like inside. So if I get a reman motor I have a few questions.

 

First of all, if the new motor is kicking out 20% more hp than stock, are the standard transmissions up to the job? Everything I read about the LQ1 states it was derated precisely because there was no trans that could stand up to the abuse it could deliver. At 240hp and 285ftlbs of torque, am I not likely to leave chunks of my stock '93 transmission all over the road?

 

Regarding the transmission, this is a good time for a major trans service, but with a new engine, should I rebuild the trans as well?

 

Also, nobody ever seems to make a distinction between the 91-93 vs 94+ engines when talking about reman engines. Is it not the case that up to '93 we have MFI and on 94 and higher it is SFI? If so, wouldn't a '93 also need a new ECM if the new engine was an SFI engine (I hope not)?

 

I was greatly saddened to hear and feel my poor CS Convertible dying like that, as I was hoping the next money would have been to redo the interior (I bought it 5 years ago in decent shape, but it does need some work). Ah well, a new motor it must be.

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Also, nobody ever seems to make a distinction between the 91-93 vs 94+ engines when talking about reman engines. Is it not the case that up to '93 we have MFI and on 94 and higher it is SFI? If so, wouldn't a '93 also need a new ECM if the new engine was an SFI engine (I hope not)?

 

the newer reman's can work in the older cars. my Z is an example.

 

however, if i were in your shoes, i would get a harness, pcm and 4t65-e from a 97 Z34. tuning ability and stronger trans.

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however, if i were in your shoes, i would get a harness, pcm and 4t65-e from a 97 Z34. tuning ability and stronger trans.

 

I keep seeing references to replacing the 4t60-e with the 4t65-e, and I must assume it is a relatively bolt on replacement (pcm and harness being the difference). I assume the PCM would be for an SFI engine and not an MFI engine as well. So I would think that when asking for the reman motor I should ask for a '94 3.4L or newer unit?

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however, if i were in your shoes, i would get a harness, pcm and 4t65-e from a 97 Z34. tuning ability and stronger trans.

 

I keep seeing references to replacing the 4t60-e with the 4t65-e, and I must assume it is a relatively bolt on replacement (pcm and harness being the difference). I assume the PCM would be for an SFI engine and not an MFI engine as well. So I would think that when asking for the reman motor I should ask for a '94 3.4L or newer unit?

 

if not, i would think that it definitely not have a cam sensor, so that would make sense.

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I spoke with the rebuilder and as I would prefer to continue with a DOHC they recommended rebuilding my specific engine, which they will rebuild using better than the original factory parts. Doing this will ensure I have no compatibility issues since I will have the same trans as before.

 

Here was the most surprising part. I asked if they thought I should rebuild the transmission and they said no, odd as that may sound. The reasoning which I understood after thinking about it was that if there is nothing wrong currently with the trans, then leave it alone. It has lasted 220K kms so far, it shifts properly and doesn't leak, so who knows how much longer it will last. Worst case, the newer stronger motor does kill the trans, and I would rebuild it anyway. In the short term, I save the rebuild cost.

 

These guys would not be the ones to rebuild the trans in any event, so it is not that they are trying to create a worse problem for me later, however I did find it an interesting perspective to take on it. In any event, I will do a full transmission service as it is due anyway.

 

Now all I have to do is line up the cash to get the work done.

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