How can I add compression to a built engine?

[jz56oval]

Hi

I have a 2110 cc motor and the builder made it set at 7.2:1 which really low and I was wondering what I need or can do to up this number to around 8-9 compression. Is this an easy fix or hard. Im assuming I will need to take the engine out of the car and remove the heads, correct? Anything else? Thanks for the help and info in advance.

Jason

[[email protected]]

Depends.

Engine out.
Heads off.
CC the heads.
Measure deck height.

Post those #s here. Generally you want DH .040-.070". If you are already in that range then you have stupid big chambers.

The deck height is the first thing to fix. But know that as you tighen up the deck, you will need shorter push rods (shorter by the same amount), assuming (big assumption) that the builder knew how to set the rocker geometry in the first place. This is a crap shoot because we already know he doesn't know how to match compression with cam.
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[jz56oval]

I don't know the deck height right now and the build died a few years back. I will post later. What do you obtain big chambers?

[sgmalt46]

we need more info. was that static or dynamic comp ratio? cam ? ect...
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[Dale M.]

If you deck height is correct (around .050) solution to bring up compression ratio is to have head fly cut to reducer combustion chamber size.... You need to "CC" the chambers to see where they are now, and then determine how much to cut from heads to reduce chamber to size that gives you CR you want....

http://www.cbperformance.com/v/enginecalc.html

The above calculator may help you work out the "numbers"...

Note: According to Bill Fisher in his book "How to Hotrod Volkswagen Engines" he states for every .001" of fly cut reduces combustion chamber size by 0.157 cc.... Something to play with when running the numbers....

Also you may want to look up on i-net is "how to cc heads"...

Dale
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[Dan Ruddock]

Low CR engine like extra timing and a leaner mixture. Try fooling with that but be careful not to go too far. Yes a CR raise would be the best thing to do. What cam does it have?

Dan

[jz56oval]

Can is

82 crank Engle cam wv25

Heads are

D R D racing
44x37.5

DRD Website says the heads are 58cc's. Is this to big?

[Howard 111]

That CR sounds fine to me. The days of high CR are over. If it's not fast enough, put a turbo on it.
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[bugguy1967]

[bugguy1967]

If you mean an Engle W125, you'll need anywhere from 9.5 to 10.5:1 compression, depending on what type of fuel you want to use. If your deck height is fine, then you need to flycut your heads to shrink those chambers. Your whole combo is suffering from that weak comp setting (shakes head).

[jz56oval]

Sorry it's a VZ-25. Check the specs card

[GTV]

Yep, 8.5-9:1.

Pull the motor, remove the heads and post back here.
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get the CR up to 9:1 for that cam to work properly. IMO.
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[Dan Ruddock]

If this a street car !!!

While you at it I would yank out that cam at the same time and run a W120 instead if you want a quiet long lasting engine.

The VZ cams beat the valve train to death and I never recommend them for a street car.

Also those who justify running very high CR because modern cars do is flawed.

1. Vw's are not water cooled.

2. Vw's don't have knock sensors.

3. Vw's don't have direct injection or even fuel injection (well most don't).

Dan

[jz56oval]

This is in a weekend car for a round town and some freeway driving. Thanks for the info everyone. I just need to get the deck height now. And possibly remove this cam. Any one else run this cam? What are the pros or cons of this cam?

Any recommendations on a different cam that I should run? What I the difference between a 120 and 110.

[PumaGTe]

[spencerfvee]

Hi the vz 25 cam you have is for midget/crc.trk./off road comp. this cam has very fast ramps It slams the valves. Down on the valve seats it wears out the valve guides. And over time will wear out the lifter bores on your case it's a off the road cam for raceing only not a very friendly street cam .it likes to be run at high RPM .like the guy says go with a 110 or 120 cam spencerfvee quote="jz56oval"]This is in a weekend car for a round town and some freeway driving. Thanks for the info everyone. I just need to get the deck height now. And possibly remove this cam. Any one else run this cam? What are the pros or cons of this cam?

Any recommendations on a different cam that I should run? What I the difference between a 120 and 110.[/quote]

[jz56oval]

Im definitely not doing any track racing. Im gonna eventually remove the cam and check deck height. Is splitting the case a hard task? Im thinking not, but just thought Id ask as I havent done this before.

[GTV]

Pro: lots of valve lift with stock rockers (cheap), good for power.
Con: lots of valve lift with stock rocker (all the lift is at the cam, hard on lifter bores)
A 110 has slightly less duration, and of course less lift (with the same rockers). Comparatively, it will move the power band slightly down.
A 120 has more duration and also less lift with stock rockers. It will move the power band up. With an engine as large as 2110, I would use the 120.

How deep you go depends on your budget. Splitting the case can easily snowball.
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[jz56oval]

looks like a 120 is what I want and need. might see if I can find someone to split it open or I might.