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2.0-4 with 103mm p&c's Question

I've got a 914 2.0-4 engine that I'm considering rebuilding with KB 103mm piston and cylinders. The engine will be used in a street car where low end torque is more important than top hp. I'm wondering if the stock heads will flow enough or do I need to port them with larger valves.

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Craig Backer
Old 12-07-2007, 08:10 PM
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In a recent conversation with my machine shop that specializes in flowing Harley MC heads, he told me that they use smaller valve sizes than others which improves the velocity at the valve and sprays the air/fuel mix "like putting your finger over the end of a garden hose". This makes for more low end torque where "most harley guys ride".

It sorta makes sense to me.
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Old 12-08-2007, 06:25 PM
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As I mentioned recently, the current thought is that 103s are not usually what you want. The quality of the ones currently available is less than stellar, and they don't tend to cool that evenly and don't last as a result. Most people recommend going no larger than 96es unless you switch over to the $$$$ nikasil-plated aluminum cylinders.

96x71 is 2056cc, which is a nice little motor. The 2.0 heads should probably flow well enough for it unless you're revving the heck out of it.

The guys in the "Type 4um" on http://www.shoptalkforums.com seem to know a good bit about these engines. Jake Raby at http://www.aircooledtechnology.com appears to be on the leading edge of development for them, and generally has a very good reputation.

--DD
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Old 12-09-2007, 03:36 PM
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Adding bore without a coefficiently effective head will just move the power band down, crippling performance.

Big bores require effective heads if you intend to maintain a broad powerband, good mileage and temperature control.

Our key to superior success is optimizing stroke and keeping bore sizes smaller. I make over 200HP with 11 different combinations with only adding 2mm of bore size.

It is all in the combo-
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Old 12-10-2007, 08:26 PM
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Quote:
Originally Posted by NOTASIX View Post
I make over 200HP with 11 different combinations with only adding 2mm of bore size.
Are you talking about adding 2mm of bore to a 2.0 liter with a stock 71mm stroke?

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Craig Backer
Old 12-10-2007, 09:40 PM
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Quote:
Originally Posted by NOTASIX View Post

Big bores require effective heads if you intend to maintain a broad powerband, good mileage and temperature control.
I'm wondering what would need to be done to the 914 2.0 head to make it effective with the 103's.
Old 12-10-2007, 09:44 PM
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Add 2mm of bore instead of 9mm of bore...
Your oil temps, head temps and wallet will all appreciate this.

Do some searches on www.shoptalkforums.com on the topic of 103mm cast iron cylinders and you'll see hundreds of posts from yours truly about the negative aspects of cast iron 103mm cylinders. There is a good reason we call them "Cast iron clunkers".

Adding stroke to the TIV engine is a very effective means of adding displacement and broadening the power output, doing this also doesn't require as much material to be removed from the heads (none) or case (they slip right in).

The quality and issues that are created by 103mm cast iron cylinders are what sparked my development of the medium displacement engine combinations 2270 and 2316 back in the late 90s. These engines make gobs of usable power, don't have longevity or reliability issues and can be used for every application from a powerful daily driver to A/X, DE or full race use.

Now, if you intend to use a 103mm bore effectively the heads will need to be opened to 115mm OD and you'll need to size the ports for the camshaft that will be used and the intended RPM. Typically a set of heads that are effective for a 103mm bore to make 150HP cost 500.00 more than the same head that will make 150HP on a 96mm bored engine if done by a specialist that does nothing except TIV heads.

One of the biggest problems that can be self induced at this stage of the design stage is applying the "Bigger is better" mind set. These big bores that are applied incorrectly, without the use of genuine LN Engineering "Nickies" cost people money and failures every year.

They have to come to me to solve their problems, don't be a statistic-
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Old 12-11-2007, 04:53 AM
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For those of you who don't like doing the math, 2270cc is 96 bore x 78.4 stroke; 2316cc is 96 bore x 80 stroke.

And I was following along on the World BBS as one of the guys over there was assembling a 2270 and watching as Jake ran it on the dyno, making 200 HP. Pure awesome out of a <2.3 liter engine, and not exactly a peaky powerband either!!

--DD
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Old 12-11-2007, 07:05 AM
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I ran a 103mm setup for over 12 years with absolutely no problems whatsoever. I did port my heads, 48mm intake valves, stock exhaust, 44mm Webers, H grind cam, NO external oil cooler, and I ran it hard, seeing 7000rpm fairly often. Pulled 7000 in 4th, 6400 in 5th when I chickened out.
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Old 01-19-2008, 05:52 PM
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