SVX Network Forums Live Chat! SVX or Subaru Links Old Lockers Photo Post How-To Documents Message Archive SVX Shop Search |
IRC users: |
#16
|
||||
|
||||
Re: Increasing Compression
baza was I dreaming or did you tell me you have the standard cams in your motor?
Tony
__________________
1995 - SVX 700,000 K Mine, DMS Struts to lift car 2in. Tyres Wrangler Silent Armor 235/70R16, PBR Radiator. 6 speed with DCCD and R180 rer diff, Heavy duty top strut mounts front and rear. Speedo correction box fitted. New stero (gave up on the old one). Back seat removed and 2 spare tyres fitted for desert driving. ECUTune SC sitting in the box for the next SVX. 1992 - SVX 255 K Wife (Want to stay Married so not allowed to fit SC) 1992 - SVX Pearl with black roof race car roll cauge etc ready to race. Ex Tasman Targa car. 1995 - SVX Green low k mint condiation. 1995 - SVX Rally car, ex Matts car. Now to be used on track. 1992 - SVX red & Black being converted to Mid Engine. 1995 - SVX Red 143,000 bit rough. Owned 5 others Subaru back to a 1974 1400 GSR. |
#17
|
|||
|
|||
Re: Increasing Compression
That's right mate, standard cams at this point in time. They turn rather asthmatic around 550-600 bhp which from what I recalling Ecutune Mike saying it's mainly the exhaust cam.
|
#18
|
||||
|
||||
Re: Increasing Compression
OK, Tony,
On our stock 10 to 1 Compression Ratio engines we have 3318cc, or about 202.46 cubic inch displacement. That should work out to 3.318 cc (or 20.246cid) above the piston at TDC. You now have 11 to 1 CR on a 3.3L, or 202 CID engine, with a bore of 97mm, (roughly) or 3.815". This has been done with different pistons. (As far as I know.) So, the displacement, above the piston at TDC has to be about 301.636cc, (or 18.405cid.) To get a 14 to 1 ratio the above the piston displacement now would have to be 237cc (or 14.461cid.) Since there is only a reported 0.060" clearance, and getting a thinner head gasket by say 0.030" would only increase the compression ratio up to about 12.384808 to 1 CR. AND you still have the problem that Harvey mentioned that you have to "adjust" the cam sprockets to correct the timing. No mate there is only 0.60" between the piston and the head, so you can't push them up any more. Shaving the heads is not the go as it will need adjustable cam pulleys to keep the timing right. Higher comp pistons would be the best. Harvey. I have not heard of anyone welding the heads to increase compression, but it sure sounds more expensve than, and risky then a bigger bore resulting in both more displacement, and higher compression.
__________________
www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#19
|
||||
|
||||
Re: Increasing Compression
The reason I mention it is that it has been banned in some rules,
have anyone else heard of it being done?
__________________
1995 - SVX 700,000 K Mine, DMS Struts to lift car 2in. Tyres Wrangler Silent Armor 235/70R16, PBR Radiator. 6 speed with DCCD and R180 rer diff, Heavy duty top strut mounts front and rear. Speedo correction box fitted. New stero (gave up on the old one). Back seat removed and 2 spare tyres fitted for desert driving. ECUTune SC sitting in the box for the next SVX. 1992 - SVX 255 K Wife (Want to stay Married so not allowed to fit SC) 1992 - SVX Pearl with black roof race car roll cauge etc ready to race. Ex Tasman Targa car. 1995 - SVX Green low k mint condiation. 1995 - SVX Rally car, ex Matts car. Now to be used on track. 1992 - SVX red & Black being converted to Mid Engine. 1995 - SVX Red 143,000 bit rough. Owned 5 others Subaru back to a 1974 1400 GSR. |
#20
|
|||
|
|||
Re: Increasing Compression
Quote:
Reason why is I've done a fair bit successful AVCS tuning on the intake cam (02-07 STI heads). As most know it effectively advances the intake cam during low end RPM and you wind it back to zero as revs and air flow climbs. The result is a massive improvement in low end torque. 0 advance gives the best top end (no bottom end) so theoretically a couple more degrees of retard will help with more top end. Also the exhaust AVCS works by retarding the cam as the rpm and airflow climb - retarding makes more top end power. So in english, decking the head in an EG33 and the resulting timing belt effects which cause overall retardation of all cams should if anything make the car more powerful up top due. Last edited by bazza; 05-29-2012 at 09:52 PM. |
#21
|
||||
|
||||
Re: Increasing Compression
Matt tried shaving the heads and had problems part because you can't buy adjustiable pulleys for the cams on our engines.
To get 14:1 how much has to be shaved off the heads? Tony
__________________
1995 - SVX 700,000 K Mine, DMS Struts to lift car 2in. Tyres Wrangler Silent Armor 235/70R16, PBR Radiator. 6 speed with DCCD and R180 rer diff, Heavy duty top strut mounts front and rear. Speedo correction box fitted. New stero (gave up on the old one). Back seat removed and 2 spare tyres fitted for desert driving. ECUTune SC sitting in the box for the next SVX. 1992 - SVX 255 K Wife (Want to stay Married so not allowed to fit SC) 1992 - SVX Pearl with black roof race car roll cauge etc ready to race. Ex Tasman Targa car. 1995 - SVX Green low k mint condiation. 1995 - SVX Rally car, ex Matts car. Now to be used on track. 1992 - SVX red & Black being converted to Mid Engine. 1995 - SVX Red 143,000 bit rough. Owned 5 others Subaru back to a 1974 1400 GSR. |
#22
|
|||
|
|||
Re: Increasing Compression
Quote:
Yours is out a bit, I make it 42.5 cc for a 14:1 ratio. Comp ratio is, swept volume, plus the clearance volume, divided by the clearance volume. Yes welding the heads would be a huge job for very little return. There would be a big chance, that you would change the shape, to the detriment of the combustion turbulence, which would cost you a lot more than the 2% gain. Harvey.
__________________
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. |
#23
|
|||
|
|||
Re: Increasing Compression
Quote:
Also for your interest Tony, adjustble pulleys available on eBay.co.uk ... 400 pounds including delivery, just checked, search "EG33 pulley" or "EG33" etc. |
#24
|
|||
|
|||
Re: Increasing Compression
Quote:
E85 is a good fuel, if full advantage is taken of it, but it is a case of what is the engine going to be used for? Like I can't imagine Tony using it, as he couldn't carry enough to get to the next pump. For circuit racing, especially if the regs only allow, 'pump gas', you would use it. In your case it is almost essential to allow the boost that you use. As I said before, it depends on what fuel you are going to use, and build the engine to suit. There is no real point in chasing a number, just to use it. Harvey.
__________________
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. |
#25
|
||||
|
||||
Re: Increasing Compression
Were is Matt, would be good to see if he thinks shaving the heads has any futur?
I sent a email to Mike about high compression pistons but did not hear a single word back. Tony
__________________
1995 - SVX 700,000 K Mine, DMS Struts to lift car 2in. Tyres Wrangler Silent Armor 235/70R16, PBR Radiator. 6 speed with DCCD and R180 rer diff, Heavy duty top strut mounts front and rear. Speedo correction box fitted. New stero (gave up on the old one). Back seat removed and 2 spare tyres fitted for desert driving. ECUTune SC sitting in the box for the next SVX. 1992 - SVX 255 K Wife (Want to stay Married so not allowed to fit SC) 1992 - SVX Pearl with black roof race car roll cauge etc ready to race. Ex Tasman Targa car. 1995 - SVX Green low k mint condiation. 1995 - SVX Rally car, ex Matts car. Now to be used on track. 1992 - SVX red & Black being converted to Mid Engine. 1995 - SVX Red 143,000 bit rough. Owned 5 others Subaru back to a 1974 1400 GSR. |
#26
|
||||
|
||||
Re: Increasing Compression
Quote:
but I was speaking of the combined head volume, for all six cylinders.
__________________
www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#27
|
||||
|
||||
Re: Increasing Compression
Quote:
Or do you believe that the tensioner would equalize the timing?
__________________
www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link Last edited by svxfiles; 05-30-2012 at 05:05 AM. Reason: Thought about my question... |
#28
|
|||
|
|||
Re: Increasing Compression
Prolly, I drew it all up before on paper but then confused myself again lol. Need to spend more time figuring it out.
|
#29
|
||||
|
||||
Re: Increasing Compression
Actually I gave it a little more thought and I believe that the right bank would be a little retarded, and the left bank would have double the amount of retard because all of the slack,
(Due to a shorter distance from the crankshaft to the camshafts) would be between/after the left camshaft and the crankshaft. Left cam is 0.030" shorter, Right cam also 0.030" shorter, ALL belt slack is adjusted out after the left cam SO, get custom pistons to up the compression ratio if you like, cuz shavin heads won't do it.
__________________
www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#30
|
||||
|
||||
Re: Increasing Compression
Two questions
If shaving the head is the way to go how much needs to be shave to increase it to 14:1. Does any one know were to get the piston if thats the way to go. Harvey the higher compression is for the race car. Tony
__________________
1995 - SVX 700,000 K Mine, DMS Struts to lift car 2in. Tyres Wrangler Silent Armor 235/70R16, PBR Radiator. 6 speed with DCCD and R180 rer diff, Heavy duty top strut mounts front and rear. Speedo correction box fitted. New stero (gave up on the old one). Back seat removed and 2 spare tyres fitted for desert driving. ECUTune SC sitting in the box for the next SVX. 1992 - SVX 255 K Wife (Want to stay Married so not allowed to fit SC) 1992 - SVX Pearl with black roof race car roll cauge etc ready to race. Ex Tasman Targa car. 1995 - SVX Green low k mint condiation. 1995 - SVX Rally car, ex Matts car. Now to be used on track. 1992 - SVX red & Black being converted to Mid Engine. 1995 - SVX Red 143,000 bit rough. Owned 5 others Subaru back to a 1974 1400 GSR. |
|
|