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Date:         Sat, 16 Oct 1999 00:29:13 EDT
Reply-To:     kenneth d lewis <kdlewis@JUNO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         kenneth d lewis <kdlewis@JUNO.COM>
Subject:      Re: 1.9 heads on a 2.1 engine?
Comments: To: Vantaztik@aol.com

Roger; This is news to me. I thought both heads were the same. The Bentley refers to ONE head for both engines. Anyway, here are some formulas so you can decide for yourself. First some definitions:

Squish volume= The volume in the cylinder when the piston is at top dead center.

Cylinder volume= the volume swept by the cylinder i.e. 2.1L=525cc; 1.9L=475cc

If memory serves me compression ratio is given by the following formula:

C.R.= (Cylinder volume+Squish volume) / Squish volume

Solving for Squish volume I come up with:

Squish volume= cylinder volume/ (C.R.-1)

Assuming a compression ratio of 9:1 in both engine;

Squish volume for the 2.1L= 65.625cc Squish volume for the 1.9L= 59.375cc

This supports your claim of approximately 5cc difference between heads. Now lets recalculate using 2.1L volume and 1.9L squish volume:

C.R.=(525+59.375)/59.375

C.R.=9.84:1

There is one important piece of data we may or may not need to take into account; the 2.1L has a longer stoke. So how much of that change in squish volume is due to different heads and how much is due to different stroke? I will leave that question open for debate.

FWIW let's calculate stroke assuming the heads are the same. Bentley only mentions one piston for both engines; 9.4 cm in diameter. I come up with a stroke of 7.565cm for the 2.1L and 6.8475cm for the 1.9L.

That's enough math for tonite, I still have to go out and finish installing the relays to boost the voltage to the headlights on my transporter. I will mull these figures over and get back with you.

Drive Safely & Good Luck Ken Lewis<Kernersville,NC>86 VW crewcab;60 T-5 Coupe

On Thu, 14 Oct 1999 21:35:24 EDT Roger&Zoe Ann Banker <Vantaztik@AOL.COM> writes: >Hi all. My local mechanic (a reputable fellow) rebuilt an engine 6000 >miles >ago with 1.9 heads on a 2.1 engine. The cc loss is minuscule, maybe >5cc, but >the compression goes way up to 180. According to the Bentley, up to >189 is >acceptable, so this looks good. I rode in it today, a standard 1987 >Vanagon, >and the power increase was quite noticeable. It runs smooth, no >overheating, >no problems. Now mine is being rebuilt, and I told the mechanic to >get 1.9 >heads for my 2.1. Has anyone tried this? Aside from the need for >premium >gas, are there any drawbacks? I am only interested in low end power, >so I >don't want big valves, ratio rockers, hot cams, or any other stuff >that needs >high rpms to be effective. I am also getting a performance exhaust >system >from Fast German Auto. >Will this set-up work well, and are there any other low end >performance >goodies I am overlooking? >Roger & Zoe Ann Banker >1987 Syncro Adventurewagen

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