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PostPosted: Fri Oct 25, 2013 4:38 pm 
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Hello, i'am searching for information, of max bore size for 4g61 engine, i'am thinking of building 4g61 with 85, or 85,5mm bore pistons from 4g63 engine, as far as i know, the castings for 4g61, 4g63 and 4g64 block's are the same, so 85,5 bore will not be a problem. Is there any simmilar builds has been allredy done in this forum?

setup;
4G61 block, crank, (stock rods?)
4g63 pistons (cast/forged/evo9) ?
hx35
1g kead
fidanza aluminium flywheel
tubular exhaust mani
bore/stroke 85,5/75 mm
rod lenght 150mm
engine cc 1700
rod ratio 2.0
bore/stroke ratio 1.14

tune plan :

9k rpm redline
30+ psi boost
e85
400bhp+
spool up 5k rpm+

Car mirage Ca0 1.6glxi fwd :)

any thought's or suggestions would be welcome :)


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PostPosted: Fri Oct 25, 2013 5:35 pm 
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You can do 9,000rpm easily on a standard 4G63 with the balance shafts removed. No need for fancy stuff. I rev mine to 9,000 every time I drive it.

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

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PostPosted: Fri Oct 25, 2013 5:42 pm 
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Ditto for a standard 4g61. That engine has a stroke of only 75mm, versus 88mm found in a 4g63. No need to overbore a 4g61 to make it rev.


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PostPosted: Fri Oct 25, 2013 5:47 pm 
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Quote:
Ditto for a standard 4g61. That engine has a stroke of only 75mm, versus 88mm found in a 4g63. No need to overbore a 4g61 to make it rev.
Right, bore really doesn't have anything to do with how high you can rev an engine. It's all about the stroke and the rod length. 4G63 has a 1.7:1 rod ratio from the factory, which is perfect for high-revving.

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus


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PostPosted: Sat Oct 26, 2013 3:18 am 
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you dont understand me, overbore is only bor CC capacity, and offboost response.
I had 4g61 (NT), 4g63(NT), 4g67(NT) and 4g63T (1g 7bolt turbo with some mods; no bs, ported head, cams, t3/t4)
but as far as i remeber 4g61 spins i high revs with more fun than 4g63 or 4g67. because it has short stroke, which helps alot in high revs, and it has less torque than 4g63, because there is no need of torque in light fwd car.


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PostPosted: Sun Oct 27, 2013 1:57 am 
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Quote:
you dont understand me, overbore is only bor CC capacity, and offboost response.
I had 4g61 (NT), 4g63(NT), 4g67(NT) and 4g63T (1g 7bolt turbo with some mods; no bs, ported head, cams, t3/t4)
but as far as i remeber 4g61 spins i high revs with more fun than 4g63 or 4g67. because it has short stroke, which helps alot in high revs, and it has less torque than 4g63, because there is no need of torque in light fwd car.
It is a much shorter stroke with the same rod length, and this does help with revving, but you have to rev it very high to see any benefits. Higher than any valvetrain that's available can support, and higher than any factory transmission can safely shift at.

_________________
91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus


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PostPosted: Mon Oct 28, 2013 4:37 pm 
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what are max hp number for 4g61 on this forum? i tnow that stock 4g63 6bolt engine with right tune, can handle 500hp with stock crank, pistons and rods. i think 4g61 can handle the same power level, but in higher rpm and boost, because of less displacemen. o I'am wrong?


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PostPosted: Mon Oct 28, 2013 4:44 pm 
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what are max hp number for 4g61 on this forum? i tnow that stock 4g63 6bolt engine with right tune, can handle 500hp with stock crank, pistons and rods. i think 4g61 can handle the same power level, but in higher rpm and boost, because of less displacemen. o I'am wrong?
People have done over 600whp on a stock 4g63 bottom-end. There are examples of even more than that out there. The 4g61 can easily handle the same amount of power, it's basically the same engine. The better rod-ratio will mean that it can rev higher for longer periods of time and be happy, and probably have a broader, flatter torque curve even though it won't be producing a lot of torque necessarily. The displacement doesn't have as much to do with it as the overall dimensions of the engine.

_________________
91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus


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PostPosted: Fri Nov 01, 2013 10:04 am 
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4g61t may have less cc's, but there is slightly less rotational mass, with rods as strong as the 4g63. So in theory the 4g61t could make more power than the 4g63, but torque may suffer. But hey a turbo is the replacement for the missing displacement. The trannys for these older mitsu's are probably made of hopes/dreams and glass. Have one professionally built, or have a couple spares if you intend to up the horsepower/abuse it. Unless you get rid of the funbox and go auto.

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PostPosted: Sat Nov 02, 2013 10:06 am 
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Straight up dog box made for an AWD 2.0 GVR4 or DSM, and you are laughing. PPG or whatever their name is in Australia, and I believe there may be a few more. The only way to make it shift with authority (because you cannot pussy foot your shifts with a dogbox) and take the high RPM's for any period of time. And, the sound of a dogbox full of straight cut gears is so enticing too. Your neighbours will love you as you whine down the street.

Keeping these motors making power in a slightly lower power band, keeps them shiftable and streetable. Period. Track cars, are another story altogether.


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PostPosted: Sat Nov 02, 2013 9:01 pm 
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I spoke with my machinist about this today. According to his calculations, a 4g61 with 4g63 pistons will make a 1.736 liter engine. Due to me having issues sourcing a good std. bore 63 block, I just dropped my spare 61 block off with him to bore out for the new pistons. We will see how it turns out.


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PostPosted: Sat Nov 02, 2013 10:05 pm 
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Joined: Sun Sep 02, 2012 9:52 am
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Location: Astoria OR
please keep us updated on how boring the 4g61 block goes

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PostPosted: Sat Nov 02, 2013 10:07 pm 
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What about pin height and crown? The 61 has a lower deck than the 63, so a stock 63 piston may ride too high.

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Early 2000's: 1992 Summit sedan - 14.1 @ 100.9mph w/ 155/80 13s
2012: 1989 Dodge Colt GT Turbo - 14.9 @ 100mph, 10psi/s16G


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PostPosted: Sat Nov 02, 2013 10:36 pm 
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Quote:
What about pin height and crown? The 61 has a lower deck than the 63, so a stock 63 piston may ride too high.
I noticed that, but the plan is to run evo8 pistons. Those are shorter too. Everything is at the machine shop so I can not take measurements yet, but the few measurements we took make it look promising. It might have a bit higher compression, but I will just run a thicker head gasket if it is too high.


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PostPosted: Sun Nov 03, 2013 8:12 am 
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Cool, post up any updates, I like this sort of thing :).

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Early 2000's: 1992 Summit sedan - 14.1 @ 100.9mph w/ 155/80 13s
2012: 1989 Dodge Colt GT Turbo - 14.9 @ 100mph, 10psi/s16G


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