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96mm over bore
Posted: Tue Apr 10, 2018 5:31 pm
by balemo
Hi all Has anyone here put patrol pistons in their road car?
We do it in speedway car but wondering if anyone has tried in road car.
Regards Dale
Re: 96mm over bore
Posted: Wed Apr 11, 2018 10:55 am
by balemo
Should have mentioned its a 4G54 and i want it as a basically standard everyday driver. No balance shafts,34 Weber conversion from ReCarb, extractors, 2"system and Acell coil.
Re: 96mm over bore
Posted: Thu Apr 12, 2018 8:20 pm
by Superscan811
The web between the cylinders would be VERY thin.
Bore centreline spacing 101.1mm.
96mm pistons.
This would equal 5.1mm between the cylinders, and almost a 2.9l
Not a good recipe for reliability, but would be more torquey.
Re: 96mm over bore
Posted: Fri Apr 13, 2018 8:45 am
by balemo
Yeah it pulls awesome in the race car and had no issues in the bores or with heat (do run methanol though)
Im rebuilding an NG Pajero as full time drive car for business and pleasure and i want that bit more grunt. Hmm maybe back to the drawing board to find another solution.
Re: 96mm over bore
Posted: Sat Apr 14, 2018 6:36 pm
by Scorpma82
EFI conversion?
E85 tuning?
Turbocharging?
Avenues I'd look at before any "drastic"
Re: 96mm over bore
Posted: Sat Jun 30, 2018 9:01 pm
by barana
Hmm it still could be possie on a road car.... 96mm with the std bores would shed alot of heat into the coolant.. And very possibly cavitate on the outer bore surfaces... You could solve the heatshed (but not powerloss) by a waterless coolant, the aussie w.c. or evans.
Secondly, your rings would have a hard time holding decent compression and maybe even wear ring lands from thin bore flex. Ie the bore actually flexes as the rings pass over it heat and small loss of compression would be some indicators.
A mates mate solved this when he bored out a holden grey motor to a 2.6!!!! He installed steel liners. The rover/leyland 3.5/4.4 and 3.9/4.0/4.6 engines are siamesed like the astron and you can purchase tophat liners for them.It would be possible to machine out the bores and install tophat liners into an astron to get a 2.9.
Talking to a race engine builder about astron shaft removal he said 1/4 of engines hed deshafted got rougher. I left the shafts in my rebuild, but noticed while cyl 1&2 were well within spec 2&4 were borderline with heaps less meat on them. Vibration and or heat had eaten them away. A 2.6 with heavier pistons may exacerbate the problem especially considering the counterbalance shafts are now too light to act against heavier slugs..
i would like to see a 2.9 tho
