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Location:
Lost in the K hole
Registered:
May 2002
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7m-ge model spec differences
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Wed, 02 October 2002 04:06
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ok...
1986.5 -1987 7mge has the following spec:
2,954cc 9.2:1 200@6000 rpm 185@4800 rpm
1988-1992 7mge has this spec:
2,954cc 9.2:1 200@6000 rpm 188@3600 rpm
can anyone identify the difference, either engine or ecu, that cuases the peak torque for the later model to be 1200 rpm lower?? and didnt the earlier model run the ACIS intake which was supposed to increase bottom end torque?
perhaps the earlier 7m has a better overall torque curve, just a later peak?
:wtf:
and also, are the manual and auto ecu's tuned differently at all in the 7m? is the manual more hash? better than the auto?
cheers
ed
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Location:
Brisbane
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 05:59
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I think the crank was upgraded to a double-counterweighted item at about the same time... I don't know if that would have an effect on the torque curve though. It's probably just minor differences in cam profiles and possibly manifolds, but I don't know for certain. 
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Location:
Lost in the K hole
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 10:39
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tell me more about the differences b/w these engine models...
this is the first ive heared about the later models being double counterweighted crank jobbies for eg. anything else i should know? im going to build an engine from bits of both, and obviously want to bring the beast features of each engine together.
and the auto vs manual ecu??
cheers
ed
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Location:
Brisbane
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 12:25
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All I know is the double counterweighted crank was introduced around 1988, and at the same time the redline was reduced by a few hundred rpm, but I don't know if that's related to the crank. I have seen both types of crank in 7M's so I can confirm this. The earlier 7M crank is almost identical to the 6M crank.
As for the ECU, I've heard the auto version retards the timing on gearchanges and generally has a "softer" tune, but I don't know for certain. I know two people who are running manual transmissions with auto ECU's with no problems though.
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Location:
Mildura
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 12:30
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As norbie said upto 89 the cranks weren't fully counterweighted.
They are easily identified by having 6M stamped on them.
As for the ECU's I just changed from an auto to manual ECU and can't find any real difference(bit hard to tell by seat of pants).
I though by having the ECT ECU disconnected it might have been stuffing the auto ECU up as I had alot of missfire problems at about 3300rpm,but it ended up being the AFM.
But I also have the turbo on mine too so that creates its own problems.
When I get it all back together I'll run the auto and manual ECU's back to back and see if I can find a difference.
marty
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Location:
Lost in the K hole
Registered:
May 2002
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 13:07
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Depends on end aim:
- light crank for rapid response
- heavy crank for smooth operation and low down torque.
The double counterweighted crank sounds heavy, and the 7M has enough trouble revving as it stands.
Seeing as you want to stay unsnailed, use light bits everywhere to reduce inertia and help rpm so you can get more power.
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Location:
Lost in the K hole
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 13:17
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well, i dare say that explains the differences in the torque curve as originally posted. its in the crank
cool.
that leaves me open to run the 86 ecu which'll run my ACIS intake, ill probably keep the earlier 6m/7m lighter crank, plus ive got a manual ecu to run the thing (from which i understand is more responsive, as opposed to the auto which has softer pedal response to take spike loads off the box)
cool
thanks ppl
ed
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Location:
Brisbane
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 13:54
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| gianttomato wrote on Wed, 02 October 2002 23:07 |
The double counterweighted crank sounds heavy,
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You're not wrong there. I tried lifting one once... damn near put my back out! It looks like it's come out of an industrial diesel or something... which explains why you rarely hear about 7M bottom ends coming apart.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: 7m-ge model spec differences
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Wed, 02 October 2002 14:05
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hehehe and I thought the old M series cranks were heavy....these beasts sound like something else. 
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