| Author | Topic |
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Location:
Brisbane
Registered:
May 2002
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Re: stroking a 4agze
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Wed, 25 February 2004 02:00
 
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the 7a block is taller... here's an extract from the MR2 mailing list a while ago...
| Quote: |
From: "Erik Berg" Erik_Berg@qmail4.nba.TRW.COM
Subject: Re: 4AGE/7AFE mod.
Scott Davis wrote:
Here's my question. Would it make any sense to take the crank out of a
7A-FE motor, or the rods, or both, and put them into the 4A-GE as a sort
of a "stroker kit?"
It might have been a darned good idea, except that I think it would be
physically impossible.
First of all, I think it unlikely that you could fit a crank with that long of a
stroke in a 4AGE block, without hitting things. We're talking an 8.5mm stroke
difference here, and the biggest stroker crank I've ever heard of for a 4AGE
has only a 7mm increase.
According to Mike Dowe, the rod journal on the 7AFE crank is larger, by
8mm. Also, Justin Timbrell told us (thanks for all the great data, Justin!):
To answer a previous question. The crank on the 7AFE has larger
diameters
By which I think he meant that *both* the rod and main journals are bigger.
True, Justin? OK, assuming the mains are different sizes, 'nuff said about
a crank swap. It ain't gonna happen, without spending more machining
dollars than it would probably be worth.
Next issue: deck height, compared to the compression height.
Toyota made the deck taller on the 7AFE, for a good reason!
Here's some comparison data (all in mm):
7AFE 4AGE
rod length 132.5 122
crank throw 42.75 38.5
stroke 85.5 77
OK, now, what is the difference between the compression height of a stock
4AGE and that of a stock 7AFE? Assuming the same piston in the 4AGE and
the 7AFE (which it isn't, but I suspect that is a minor deal...) it would be the
difference in the rod length plus the difference in the crank throw. In other
words:
Difference in compression height = (132.5 - 122) + (42.75 - 38.5) = 14.75mm
So, if you were actually able to stuff a 7AF crank and rods into a 4AG block,
the piston would probably stand proud of the deck by about 13 to 14mm
(half an inch-ish). Not a happy deal!
I still think the hot ticket would be to do exactly what Justin did... plop a
4AGE head on the 7A block.
Just for grins, what is Justin's CR? Can we calculate it, from the data I've
dredged up here?
I'm not sure exactly what the deck heights of the blocks are, but I'm pretty
sure they are *different* by 15.4mm. Ass-u-me-ing that to be correct, and
that Justin's original CR was 10:1 as he reported, I'm getting a result that the
chamber volume difference, with the same piston, would be 3.35cc (larger
volume for the 7AGE, compared to the 4AGE).
The total chamber volume for the 4AGE with a 10:1 CR, would be 44cc. The
total chamber volume for the 7AGE would then be 44cc + 3.35cc = 47.35cc
and therefore the CR would be..... about 10.3:1.
Well, is this correct? Can anyone find any errors in these calculations?
By the way, Justin you also wrote:
You might be wondering what happened when I turned the key the first
time ..... well unfortunately it started first time no problems and hasn't
skipped a beat since .... how boring !!!
"Unfortunately"?! Hey, that kind of bordom I could live with!
Regards,
Erik Berg
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The 7a uses a 20mm press fit gudgeon pin, the aftermarket 7a rods use a 20mm floating gudgeon pin. If you use the stock rods (ok for NA but not recommended for FI) then you can press fit the pin, with the aftermarket eagle/crower rods the gudgeon pin fits the same as the 20mm 4a rods.
You may want to dowel the crank and flywheel to add a bit more strength as the 7a uses a 6-bolt flywheel
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| | Subject | Poster | Date |
|---|
 |
stroking a 4agze
|
fatmr2 | Tue, 24 February 2004 04:29 |
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Re: stroking a 4agze
|
feral4mr2 | Tue, 24 February 2004 11:02 |
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Re: stroking a 4agze
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mrshin | Tue, 24 February 2004 11:31 |
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Re: stroking a 4agte
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fatmr2 | Tue, 24 February 2004 20:35 |
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Re: stroking a 4agte
|
fatmr2 | Tue, 24 February 2004 20:59 |
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Re: stroking a 4agte
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feral4mr2 | Tue, 24 February 2004 21:06 |
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Re: stroking a 4agte
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CLG | Wed, 25 February 2004 00:38 |
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Re: stroking a 4agze
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fatmr2 | Wed, 25 February 2004 01:44 |
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Re: stroking a 4agze
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CLG | Wed, 25 February 2004 02:49 |
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Re: stroking a 4agze
|
fatmr2 | Wed, 25 February 2004 01:51 |
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Re: stroking a 4agze
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jasonp1977 | Wed, 25 February 2004 02:00 |
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Re: stroking a 4agze
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fatmr2 | Wed, 25 February 2004 02:29 |
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Re: stroking a 4agze
|
fatmr2 | Wed, 25 February 2004 03:34 |
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Re: stroking a 4agze
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feral4mr2 | Wed, 25 February 2004 09:33 |
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Re: stroking a 4agze
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fatmr2 | Wed, 25 February 2004 20:38 |
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