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so I'm considering building a motor
I've been toying with the idea of building a motor for my SVX. I don't want to spend all that much on parts for it, and I think I'd stay stock with the block as I don't need to make any more than 300 crank and even that seems to be a lofty goal with this motor. There is so much info on this subject, but I'm hoping one of the engine guys will give me an idea of what I'm looking at. I have a motor available to me for $100 that has a broken head from an accident way back in 2000, it'sa 94 and has 63,000 miles. It needs a RH head, it's broken.
What I want to know is, can you get in hp/torque just from headwork? If I wanted to stay stock on the valve size, and I just did cams, and a polish, what kind of hp gain could I get? Would it be worth it?
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2007 GS 450h-Active Stabilizer/Radar cruise 1994 L Blue 3.70 VTD ASE Master Automobile ASE Advanced Level Specialist Toyota Master Diagnostic Technician (former life) |
#2
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Re: so I'm considering building a motor
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To get the 300HP you have to get the engine to produce the same 228ft lbs of torque at 6200, then the engine would give 300 @ 6900. There in lays the problem moving the torque peak from 4800 to 6200. The inlet and exhaust resonate, and valve duration are all centered on the 4800 point. You would have to do a lot of surgery on the inlet manifold tracts, to get it to the new resonate point the exhaust is easier. So you are left with the only option of using a small amount of duration and lift increase to stretch the torque curve further up the rev range. The inlet cam is the easiest to do, and the 247* 8mm lift does do that without affecting the low speed torque. You can get a bit more using 257* 8.75 lift cams both on the inlet and exhaust, but the low end will suffer. So if you are going to use an Auto with the 3.5 ratio, you will still need the low end of the torque curve. If you go to a lower ratio or a manual, you can get around using the low end. 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. |
#3
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Re: so I'm considering building a motor
Bah, why do anything Harvey said, when you can just install one of THESE bad boys Ultra supercharging turbo HP gainer module!!!
Install and enjoy |
#4
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Re: so I'm considering building a motor
To do cams properly, you need longer valves, springs with more compression travel before binding, and solid lifters. If you do this, along with some strong cams, you can make lots of power on a stoke short block(crank,rods,pistons). EFI Logic's EG33 impreza was making around ~285 awhp hp with a factory short block with the above mods.
Justin Quote:
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#5
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Re: so I'm considering building a motor
I have also woundring about this stuff. I have been on ECU tune website.
Are these engine parts give HP or must you have some other. I have try also to find N/A tune parts, But i have only fine these. Are the some other website that have tuning stuff for the Svx And what must will you give for get around 280-300Hp?
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Alexander (Norway) My subarus: 1992 Svx LSI 5-MT(3.54) 1998 Legacy BG 2.5L GX |
#6
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Re: so I'm considering building a motor
This is my take on it, accept or reject as you see fit.
Doing cams and valve work on this engine must surely be for the challenge challenged among us. It's an awful lot of expensive head work for F all return. Now I would see sense in leaving the cams and valves alone and going for a bigger swept volume using a rebore and larger pistons to 3.5 or 3.7 litres, I haven't done the numbers. { but if 3.3 ~ 225hp, then 3.5 ~ 240hp and 3.7 ~ 250hp without tuning.} Then, while you were buying your bigger pistons, you go for lower compression, something like 9.5 to one or so. Next you add either a turbocharger or a supercharger and compress the charge 4 lbs, maybe 6 or 7 lbs, a half atmosphere sounds about right. Some European cars like Saab and Citroen got this factory upgrade which worked very well on real roads, LPT they called it, Light Pressure Turbocharging. It should be easy and inexpensive to add a small fast spooling turbo, no intercooler, just add water injection or water/meths mix injection. It will at this stage need a new exhaust because the standard system will not breathe fast enough [have low enough back pressure] for the output. Probably because you are a technician and you have a broken head on one of the blocks you actually want to do the headwork. And we can encourage you to do it and spend all that time gaining a few geegees up in the stratospheric end of the rev range where it is only really useful for track work. And because I am not a technician, but merely a driver, I would want my engine to give me a kick in the back, not a kick in the wallet. Horses for courses, eh? Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl Last edited by svxistentialist; 09-11-2009 at 10:12 AM. |
#7
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Re: so I'm considering building a motor
Very well said Joe!
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#8
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Re: so I'm considering building a motor
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The power improvements from the new 3.5 litre shortblock were not as radical (+26 whp), but the torque also got proportionately better, and it picked up across the entire powerband as well (including low rpm). Engine flexibility was improved too. It's running 11.95:1 compression on 93 octane pump fuel with 38 degrees of total timing. |
#9
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Re: so I'm considering building a motor
is it even possible to bore to 3.7L? and even then the engine would be more fragile wouldnt it?
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Tranny goes in, tranny comes out, tranny goes in.....AW ****, tranny comes out.... |
#10
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Re: so I'm considering building a motor
Yes it is possible. Check YouTube
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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. |
#11
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Re: so I'm considering building a motor
Thanks Soviet.
I'm not into raining on anybody's parade or dampening anyone's aspirations, but to me valve work and camshaft work and head work is primarily about delivering horsepower higher up the rev range, and mostly useful for racing, not road cars. Add to that the SVX is a heavy car with a sluggish gearbox and the obvious upgrade it needs is more torque low down in the rev range to get its fat butt rolling. Bigger brakes are nice too.
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#12
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Re: so I'm considering building a motor
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100 x 75= 3.534L 102 X 75 = 3.677L 100 x 78.5 = 3.699L |
#13
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Re: so I'm considering building a motor
Ya'll talked me out of it. Haha. I would consider boring and sleeving but that is a PITA on an open deck alloy block. I think my new transmission is about the best performance mod you can make to this car without using forced induction.
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2007 GS 450h-Active Stabilizer/Radar cruise 1994 L Blue 3.70 VTD ASE Master Automobile ASE Advanced Level Specialist Toyota Master Diagnostic Technician (former life) |
#14
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Re: so I'm considering building a motor
You can still overbore the motor to 100mm with stock sleeves. That will get you all the displacement you'd need. Do some nice cams, and exhaust and you are good!
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#15
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Re: so I'm considering building a motor
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