103 mm bore x 71 mm stroke engine., Anyone tried this? |
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103 mm bore x 71 mm stroke engine., Anyone tried this? |
Charles Deutsch |
Sep 12 2003, 08:57 PM
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#1
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Unregistered |
The Scat (what a name!) catalog has a 103 mm big bore kit for the 914. Could I use these pistons & cylinders with my 2.0 case without any machining? What kind of hp and torque curves would this combination produce with a street cam optimized for mid-range power and torque? If it's well balanced, it should be a free-revver considering the stock stroke is retained, no? Btw, what are some of the bore/stroke numbers for the flat-six motors?
Thanks |
URY914 |
Sep 12 2003, 09:02 PM
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#2
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I built the lightest 914 in the history of mankind. Group: Members Posts: 123,652 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
That is a lot of questions!
1. 103's require case and head machining. 2. HP? easy question-many answers. 3. Yes 4. Don't know |
Charles Deutsch |
Sep 12 2003, 09:17 PM
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#3
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Unregistered |
I wonder what kind of engine dyno simulation software Jake Raby uses - it would be interesting to plug some numbers in and see the corresponding hp and torque curves. A few years ago, I read about the software that BMW bought for designing their engines - I wonder if it's dropped in price in the mean time. (IMG:style_emoticons/default/laugh.gif)
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tat2dphreak |
Sep 12 2003, 10:06 PM
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#4
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stoya, stoya, stoya Group: Benefactors Posts: 8,797 Joined: 6-June 03 From: Wylie, TX Member No.: 792 Region Association: Southwest Region |
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Jake Raby |
Sep 13 2003, 12:02 PM
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#5
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Engine Surgeon Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Going with a bore that big and a cast iron cylinder is asking for trouble....Some of this trouble is:
Head leaks- those darn out of round non square cylinders leak like a sieve and need 5-6 studs to keep from it... Oil temperatures- The bore size is increased 9mm over stock thats a whopping .360 about 3/8 of an inch!! Cooling that oil takes alot of work.. Head studs- the TIV has a non square stud pattern, it does not like a huge bore......Also the studs are 2 different lengths from top to bottom, and that makes for uneven expansion rates...uneven expansion warps the cylinder and even the heads and starts head leaks! heads- After you get them sealed off, you have to flow the air that a piston that big can move....not happening cheaply or easily! I felt so strongly and had so many problems with those pistons (actually anything over 100mm) that I REFUSE to use them any further. Every 100mm+ bored engine I build gets LN Engineering Nickies, or I won't put my serial # on it...simply too risky! alot of guys disagree with this, and thats fine....I can make 180 ponies from a 96mm bored engine with some stroke and correct cam and head selection and do so for 80-100K miles....I have seen 103s last 10% of that time before they have a head leak or worse. They are simply not needed, and until we correct some issues with cylinder heads and borespacing, they are a simple waste of money.(in my opinion) As for my software, I use Engine Analyzer Pro, coupled with old fashioned trial and error... |
Charles Deutsch |
Sep 13 2003, 01:48 PM
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#6
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Unregistered |
Thanks for the great information, Jake. I've decided that I'm going to just rebuild my 2.0 to stock specs (using the Euro pistons and cylinders) and build, or buy, a big-four sometime in the future. I'm going to do a web search for the software now but I'll probably get "sticker shock".
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Charles Deutsch |
Sep 13 2003, 02:34 PM
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#7
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Unregistered |
For anyone who's interested, you can download and try a demo version (beta) of the latest Engine Analyzer Pro software but you have to phone Performance Trends and ask for an unlocking code everytime you want to use it.
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