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| Compression http://www.woodsbuggy.com/phpBB3/viewtopic.php?f=3&t=1651 |
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| Author: | A. Cole [ Mon Oct 29, 2007 6:08 pm ] |
| Post subject: | Compression |
While I am waiting for my new pistons/cylinders to arrive, I have been looking into deck height. This whole deck height thing is new to me. I have always had a 1641 that was "just put together." I'll have an 1835 with stock heads. So should I worry about my compression and deck height in an 1835??? If so, what a compression ratio to shoot for? |
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| Author: | turboblue [ Mon Oct 29, 2007 6:15 pm ] |
| Post subject: | Re: Compression |
[quote='A. Cole']While I am waiting for my new pistons/cylinders to arrive, I have been looking into deck height. This whole deck height thing is new to me. I have always had a 1641 that was "just put together." I'll have an 1835 with stock heads. So should I worry about my compression and deck height in an 1835??? If so, what a compression ratio to shoot for?[/quote] They all need to be checked. Nothing like having a tight deck and a piston smacking the cylinder hea |
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| Author: | m.ralston [ Mon Oct 29, 2007 8:43 pm ] |
| Post subject: | |
You need to check your cc in your head cavity before you set your comp ratio.To up the ratio in that motor you might have to fly cut the heads. |
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| Author: | A. Cole [ Mon Oct 29, 2007 9:11 pm ] |
| Post subject: | |
I had the heads fly cut on my 1641. The copper head gasket will essentially do the same thing though, right??http://www2.cip1.com/ProductDetails.asp?ProductCode=C12%2D4579%2D20 |
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| Author: | m.ralston [ Mon Oct 29, 2007 9:18 pm ] |
| Post subject: | |
I was saying that you might have to fly cut the heads to make them have less cc's so you can run a little higher comp ratio with a stock stroke crank. Those copper rings are the way to go and you can get differant thicknesses to. |
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| Author: | rockrockets1 [ Mon Oct 29, 2007 10:35 pm ] |
| Post subject: | |
yea but with a copper head gasket you will be lowering comp |
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| Author: | DVS1 [ Mon Oct 29, 2007 11:27 pm ] |
| Post subject: | |
[quote='rockrockets1']yea but with a copper head gasket you will be lowering comp[/quote] You are right, but with copper head shims/gaskets you get a better seal between the head and the cylinders especially when the motor heats up and starts to expand. |
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| Author: | db4spd [ Tue Oct 30, 2007 10:16 am ] |
| Post subject: | |
If you plan on running race gas how much compression can you run on an 1835? |
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| Author: | kybuggy1 [ Tue Oct 30, 2007 11:03 am ] |
| Post subject: | |
I've always heard up to 12:1 on 110 octane, from there on up you need 114 . Larry |
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| Author: | A. Cole [ Tue Oct 30, 2007 4:25 pm ] |
| Post subject: | |
It looks like I need to find out what my combustion chamber cc's are and go from there. I'm going to find out for sure, but found that stock heads a about 51cc. ?? I also read that your deck height shoud be at least 1.5mm (or .06"). |
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| Author: | Roy [ Tue Oct 30, 2007 8:14 pm ] |
| Post subject: | |
You should always leave at least 60 thousanths if you are using a stock crankshaft. You can go tighter than that if you are using a good quality crank. Roy |
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| Author: | Blake [ Wed Oct 31, 2007 8:34 am ] |
| Post subject: | |
Someone once told me a zero deck height is the best, is that true Roy (with good components)? -Blake |
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| Author: | fgrir [ Wed Oct 31, 2007 9:52 am ] |
| Post subject: | |
I used 40 thousands on my stock motor (counterweighted crank). If i remember right a stroker should be minimum 60 thousands. I dont think you can run a motor with 0 deck height without wrecking the motor. Most set it up that way then add 40-60 thousands shims. Turboblue is the one to ask. |
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| Author: | Blake [ Wed Oct 31, 2007 11:58 am ] |
| Post subject: | |
I thought it was one of the Alabama guys from way back when but I don't remember. Hell, I don't even know what my 2332 has for deck height! -Blake |
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| Author: | turboblue [ Wed Oct 31, 2007 12:02 pm ] |
| Post subject: | |
[quote='blbronc']I thought it was one of the Alabama guys from way back when but I don't remember. Hell, I don't even know what my 2332 has for deck height! -Blake[/quote] 0 deck would be what we call an interference engine. The piston will interfere with the head and valves....... 
You can use 0 deck if you run a copper head gasket. Then you have to make sure the inner diameter of that copper gasket doesn't get in the way of the piston @ TDC.. This setup is not tr |
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| Author: | Blake [ Wed Oct 31, 2007 4:03 pm ] |
| Post subject: | |
Yes, I think that was it, there were copper gaskets for sure. |
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| Author: | Roy [ Thu Nov 01, 2007 6:28 am ] |
| Post subject: | |
Lots of time I will set a motor to zero deck by machining down the cylinder bases and the piston is flush with the top of the jug. When you add a copper head gasket, the thickness of that gasket becomes your deck height. Like Gary said, you cannot run a VW motor with zero deck. Even if you notched the tops of the pistons for valve clearance, the piston would hit the cylinder head. Even with 20 thousanths deck, the crank will flex enough at 6 or 7 thousand rpm's and the piston could still smack the head. Back to the orig. question and post. It is very important to know and set all of you components up properly. Compression ratio is critical to engine performance. The camshaft grind also has to be taken into consideration when picking a CR number. That's the part that is tricky. Let's face the facts here. When building a motor other than a stock one, you are trying to get more power! Compression ratio affects power directly. For every full point you increace the CR, you power goes up 5%. If you want to run pump gas only, you are limited to how high you can safely go with the number. All of your components need to be carefully measured so you know exactly where you are. If you need any help, just ask. That's what we are here for. Roy |
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| Author: | bruce 1 [ Thu Nov 01, 2007 6:47 am ] |
| Post subject: | |
0 deck with .40 copper is the way to go. |
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| Author: | turboblue [ Thu Nov 01, 2007 10:35 am ] |
| Post subject: | |
[quote='bruce 1']0 deck with .40 copper is the way to go.[/quote] That depends on the head cc's too. |
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| Author: | bruce 1 [ Thu Nov 01, 2007 2:03 pm ] |
| Post subject: | |
I can not tell everything!! 
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| Author: | A. Cole [ Sun Feb 03, 2008 10:55 am ] |
| Post subject: | |
To get the compression ratio I want I am going to have to fly cut the heads. Is it worth cutting a little extra to allow the use of the copper head gasket? |
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| Author: | DVS1 [ Sun Feb 03, 2008 11:44 pm ] |
| Post subject: | |
Definitly, in my opinion the copper shims allows a better seat between the head and the cylinders. |
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| Author: | gkeeton [ Mon Feb 04, 2008 12:34 am ] |
| Post subject: | |
I agree with Roy that machining the cylinder base's to get close to zero deck, then run a copper head gasket to get your final deck height clearence. An engine will run better if more of the combustion is taking place in the combustion chamber of the head instead of the cylinder. If you're shooting for 9:1, an engine with a .005 deck, .050 head gasket, and a 48cc cobustion chamber would run better than a .040 deck, .050 head gasket, 42cc head combo. I would get your piston to cylinder deck height at 0 or .005, then run a .050 copper gasket. Then get your heads done to the combustion chamber cc's you want to get your desired compression ratio. I've run 9.5:1 in a street Beetle with 93 octane pump gas without any problems. You can go higher with race gas, but race gas is going up just like pump gas. The gas station that has Citgo 110 by me is around $6.00 a gallon, and a buddy of mine that runs VP C16 in his race car says it's over $10.00 a gallon. Even though aviation gas is higher octane than pump gas, it's made for airplanes. I've read dyno tests with aviation gas actually had lower performance than 93 octane pumpgas. If you go riding a lot you're going to have a big fuel bill with race gas. I would take the money you may end up spending in race gas, and make your engine larger to run on pump gas. I know of someone that used to go an entire weekend at Wellsville on 10 gallons of pump gas (10 x $3.25 = $32.50). He then upped his compression to run race gas, then installed a set of dual carbs. He then ended up using around 30 gallons of race gas in a weekend (30 x $6.00 = $180.00). Do what you would like, but I would stick to 9.5:1 or lower to run premium pump gas. That's my two cents! LOL |
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| Author: | Strong [ Wed Feb 06, 2008 10:52 pm ] |
| Post subject: | |
My stroker is .010 deck with .040 head gasket with no problems. |
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