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#61
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Pistons themselves cannot dictate displacement unless you bore the engine out (read OBI's comments). The other way to increase displacement is to create a longer stroke which requirse a new crank.
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Greg 97 Red SVX LSi clean 96 Black SVX LSi beater 90 Red Eclipse GSX track ho 99 Ford F250 work horse My Locker |
#62
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i decided not to comment at all
Tom |
#63
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As for as I know, Alfa Romeo's engines are designed for a longer stroke, this is why their engines have a higher torque than other cars.
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Danny 1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon) 1967 Mercedes-Benz 250SL Euro Specs, Hard/Softtop, White/Red. Under Complete Restoration 2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection. |
#64
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Not entirley true....
One can always lower the gudgeon/piston pin height, rework the cyl head and gain a few mm of stroke this way.(I did this on a Ford 302 Jetsprint boat motor that we couldn't afford a stroker crank for!! ) The other alternative is offset grinding the crank, again, good for a mm or two. In my personal experience with Subaru Engines over the years, I have realistically doubled the overbore limit that the book recommends, (i am NOT saying this is OK to do and you will have NO probs!!), I have bored a EA82 Turbo out to .75mm and the factory limit is supposed to be .25mm!! This was my own vehicle, I came across the stuff cheap and machined my case to suit the bits I had. I then disconnected the fuel cut and drove it @ 11Psi, (std is around 7), on std Everything except Dumpipe for 35000kms!! Never had a drama.... I could go on and on about engines I have done WAAY oversize, but again, I am not Recommending it, Just my 0.2 Cents worth! There MANY ways to get your SVX pumping, I believe the best, (cheapest, most effective, most 'bling value' ), is the Twin intake setup. Cheers Sixpack Subaru |
#65
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You could bore the cylinders till they are paper thin and he still wont get 3.6 liters. According to CCR in colorado they wont go beyond the overbore limit on their svx rebuilds because the cylinder walls will get to thin and distort causing premature engine wear. They have rebuilt more subaru engines than anybody else and have the best warranty.
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EG33 Turbo Porsche 914 |
#66
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Thats just it.. if they didn't have to warranty them, think they would be willing to bore them out farther? Anywho, I had been thinking what would happen if you ground down the crank journals to be a much smaller size, however keeping the "outer" edge the same, and taking more material off the "inside" part. Essentially taking a circle, and by only grinding 340 degrees of it, (the main bearing side of the rod/crank journal), you would essentially "lengthen" the stroke by 2-3 mm. Does this even work? Like take the stock as "O", then grind it such that it is "o" Disclaimer, I am in no way suggesting you do this as it will most likely weaken the crank significantly.
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Greg 97 Red SVX LSi clean 96 Black SVX LSi beater 90 Red Eclipse GSX track ho 99 Ford F250 work horse My Locker |
#67
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Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#68
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Mr. Harvey,
I understand what you are saying, from a metalurgical standpoint. Question - how do you explain the popular 350 cu in. stroked to 383 cu in. small block Chevy engines that have been around for years and are taken up beyond the SVX's normal 6500rpm redline rotational speed on a regular basis? Thanks.
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Maximum acceleration, maximum lateral g-force...it can be done, it just takes time and $$$ |
#69
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Forged 383 cranks
Tom |
#70
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Im trying to post pictures of the pistons but im having a some trouble. I already have them in my locker down to 640x480 but i cant attach them to my post, im getting an error when i upload them on the bottom of the type box where it says manage attachments. Can anybody tell me how
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EG33 Turbo Porsche 914 |
#71
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#72
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it's hard to see for sure but it looks like the top edges are the same height and the only difference is the dish...is that correct?
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#73
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Thanks for the pictures.
There is a lot of clearance volume in that dish, It is at least the same depth as the valve cut-outs in the SVX piston. Looking better.
Still need the cylinder clearance volume, to know what the final comp ratio will be. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#74
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Looks to me like they took the same piston with the valve cut outs in it and everything and milled the dish into it.
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#75
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-Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
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