4g61t.org

The 4g61 can make power but it takes drastically higher cylinder pressures or rpm's to get there. Jared's did just shy of 600 whp corrected which at this elevation would equate to around 500 whp uncorrected. I'd like to hear how the evo 8 pistons work out if at all...

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Turning a 4g61t into 1595 cc's of FURY!
10.995 @ 134.44 - http://www.youtube.com/watch?v=bZXvcvzuWGQ

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Any further progress on this build? cuz i am looking to do a similar build. question y use the evo 8 pistons when u can use the evo 3 pistons just a question iam not to sure

As for the 61t engines:
For stock rod lengths, you must use a piston with a max compression height of 32.5mm. This way the piston will sit flush with an uncut block deck.

OR...

find some 6.000" (152.4mm) forged rods and use some aftermarket honda pistons in the 86mm bore (k series engines), which have a compression height of 30mm. This will bring the piston to within 0.1mm of uncut deck height...

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89 turbocan, 63t, GT30-13 (laaaag monster), tubular manifold by me, maf-Trans, phil-tuned ecu, bla bla bla.... you get the drift...

Having Been down this road I can comfortably say you will need custom pistons to bore that far! Despite what people think it just won't work. The pin hight won't work, you can however bore it to 86mm comfortably

Understand what u r saying but from looking at the 4g63 pistons it looks like it would work but u would have to modify the piston( shave it down to the deck height of the block) i dont no iam just saying i could be wrong

back to the topic, i did some research and find out that 4g61 pistons are 32,5 comp height, mitsubishi has the same comp height only in 3000gt but piston bore is way too big for 4g61 block (about 90mm) so my curent plan is:
Honda b20z pistons 30mm comp height -4cc dome 21mm wirst pin 84mm bore (about 8.3:1 cr on my setup)
shave 4g61 block about 2,9mm for 0,0mm piston clearance (not sure, have to do some mesurements, after boring block to 84mm)
4g63 1g 6bolt head
4g63/61 stock 6 bolt conrods 150mm
fidanza aluminium flywheel
bc valve spring kit
4g63 NT cams in-260 ex-264
acl trimetal race bearings
stock 6 bolt head, conrod, crank bolts
4g63 head hasket

any ideas?

Get bigger cams

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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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Seems like a lot of work and $$$$ to make the same power as a stock 63t. Was this for a certain class of racing or just for fun?

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Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

Nice work goin on with ur project keep it up power to a 4g61

after some mesurement's of b20z piston i found out taht it is too difficult to match this piston for 4g61 and started to look for another one, and finaly found it bmw m50b25tu is very good choice for 4g61. it has 32.5mm comp height 84mm bore 22mm full floating pin wery thick top land 8.7mm and first ringland 4mm. the psiton is flatt top with valve reliefs. on 36cc bmw's combustion camber it makes 10.5:1 CR (stroke is the same 75mm) so for dsm head it would be 8.7:1cr. Weight with pin is the same as 4g61 nt piston with 21mm pin. piston wirst pin offset 0.5mm insted of 1mm dsm
some photos of the piston:

How'd the BMW pistons worked out ? I kno this is an old thread.

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Hyundai Excel
G4cr na

Is suspect the compression ratio will be quite high. No?

Valve reliefs will have to be checked and clearanced on the piston tops.

If you measure out the actual bore on a 4g61 composite gasket, there will be room for overboring.

I suggest the 4g61 gasket over a 4g63 gasket on the principle that you would other wise create a spot for carbon to develop between the deck and head if you have too large a fire ring.
I measured a FelPro gasket here recently and it had room for 4g64 pistons with overbore IIRC.

I confirm that, like the OEM 4G63 gasket, good to use with one oversize 4G64 bore bloc
I think this is a chimera build and time lost, but Ases_b has a nice mind a take the time to search here ...