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draksia
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Joined: July 07, 2022
Posts: 14
Location: FL
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 Posted: Mon Oct 03, 2022 6:05 pm Post subject: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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I am a definitely newbie building engines but a scored a great deal on an 82mm crank so I was thinking about getting started. The plan is to build a very mild 2180 with AA thick wall cylinders since I am planning to add AC and I thought the extra heat load capacity would not be a bad idea. I have a Holley Sniper single barrel setup so that is likely going to be the limiting factor in performance for this build.
CB has their aluminum case in stock but only the 3.5mm raised deck version. I ran the numbers on the deck height and with Panchito heads with a 54cc chamber and that comes out to 8.1 compression. So taking a few CC's out of the heads could bump it up closer to 9.
My basic understanding though is that the deck height should be closer to .070 or so.
I am wanting to double check this before I start ordering parts.
Also since the AA thick wall 92's are available in a base of 92 or 94mm I am not sure the best option for the base either.
Thanks in advance. |
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67rustavenger 
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Joined: February 24, 2015
Posts: 9772
Location: Oregon
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| Posted: Mon Oct 03, 2022 6:30 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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0.040" deck height is/has been the going number to shoot for. 0.070" is a pretty big DH. IIRC, it'll run a little hotter with a larger DH. You want the combustion to take place in the head, not the cylinder.
Get the 94 cut case and order your 92TW cylinders to fit that size case opening.
That way if, at a later date you wanna build it bigger.
You don't have the case machined to fit the larger diameter cylinders.
What camshaft are you thinking of using?
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draksia
Samba Member
Joined: July 07, 2022
Posts: 14
Location: FL
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| Posted: Mon Oct 03, 2022 6:57 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| I haven't gotten far enough to figure out what camshaft , lol |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 76940
Location: Sneaking up behind you
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| Posted: Mon Oct 03, 2022 7:00 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| draksia wrote: |
| I haven't gotten far enough to figure out what camshaft , lol |
Do that before thinking about compression ratio.
What length rods are you thinking? 5.4/5.5/5.6?
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74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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67rustavenger
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Joined: February 24, 2015
Posts: 9772
Location: Oregon
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| Posted: Mon Oct 03, 2022 7:01 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| draksia wrote: |
| I haven't gotten far enough to figure out what camshaft , lol |
What's it gonna push?
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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draksia
Samba Member
Joined: July 07, 2022
Posts: 14
Location: FL
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| Posted: Mon Oct 03, 2022 7:08 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| 67rustavenger wrote: |
| draksia wrote: |
| I haven't gotten far enough to figure out what camshaft , lol |
What's it gonna push? |
a 72 standard Beetle |
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draksia
Samba Member
Joined: July 07, 2022
Posts: 14
Location: FL
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| Posted: Mon Oct 03, 2022 7:09 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| Glenn wrote: |
| draksia wrote: |
| I haven't gotten far enough to figure out what camshaft , lol |
Do that before thinking about compression ratio.
What length rods are you thinking? 5.4/5.5/5.6? |
I assumed 5.4 was the standard for an 82mm stroke |
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Brian_e
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Joined: July 28, 2009
Posts: 3293
Location: Rapid City, SD
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| Posted: Mon Oct 03, 2022 7:52 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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The 3.5 raised deck is gonna cause you some extra issues.
A new standard aluminum case from the latest batch, 82mm crank and the latest 92mm AA B pistons, and 5.4 rods should be really close to .045 or zero deck. You will need to mock everything up, and measure it all yourself. The raised 3.5mm deck will need to be machined .140" or so, or have the cylinder bases machined. This is all based on an 2180cc I just finished with all new parts, but DO NOT base your engine on what I ended up with. Measure it all yourself, they are rarely the same.
8.1 is WAY to low for just about any cam that should be in a 2180cc in a bug. Lower compression DOES NOT EQUAL COOLER RUNNING!!!!!!
You need to list how you intend to drive it. Are you a hot rodder stop light warrior, or a granny shifting cruiser never revving past 3800rpm?
The cam will dictate the RPM range the engine will make power. Don't build an engine that will rev to 6800 if you will never wrap it past 5k.
Brian
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UK Luke 72
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draksia
Samba Member
Joined: July 07, 2022
Posts: 14
Location: FL
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| Posted: Tue Oct 04, 2022 6:02 am Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| Brian_e wrote: |
The 3.5 raised deck is gonna cause you some extra issues.
A new standard aluminum case from the latest batch, 82mm crank and the latest 92mm AA B pistons, and 5.4 rods should be really close to .045 or zero deck. You will need to mock everything up, and measure it all yourself. The raised 3.5mm deck will need to be machined .140" or so, or have the cylinder bases machined. This is all based on an 2180cc I just finished with all new parts, but DO NOT base your engine on what I ended up with. Measure it all yourself, they are rarely the same.
8.1 is WAY to low for just about any cam that should be in a 2180cc in a bug. Lower compression DOES NOT EQUAL COOLER RUNNING!!!!!!
You need to list how you intend to drive it. Are you a hot rodder stop light warrior, or a granny shifting cruiser never revving past 3800rpm?
The cam will dictate the RPM range the engine will make power. Don't build an engine that will rev to 6800 if you will never wrap it past 5k.
Brian |
I am definitely more of a cruiser and just looking for something with more power than my tired 1600 that I currently have.
For sure I plan on measuring everything twice before finally assembly I would prefer to avoid machining if possible.
I was planning on a compression ration closer to 9:1 or so. |
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richparker
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Joined: November 24, 2011
Posts: 6983
Location: Durango, CO
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| Posted: Tue Oct 04, 2022 6:09 am Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| Brian_e wrote: |
The 3.5 raised deck is gonna cause you some extra issues.
Brian |
I have a CB White Rhino case with a +3.5mm deck. It’s built into a 8.1:1 compression 2275 with a Engle 110, CNC ported 044 heads and Weber IDF40s. This was built for a bus, runs like a scolded cat and produces excellent fuel economy.
I would have put a bigger cam in it, but it’s a bus engine. Is my beetle has a larger cam and it spins to the moon. As stated above, build it how you’re gonna use it.
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Brian_e
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Joined: July 28, 2009
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Location: Rapid City, SD
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| Posted: Tue Oct 04, 2022 8:56 am Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| UK Luke 72 wrote: |
| Would there be a downside to using a +3.5mm case and trimming the cylinders to hone in on the desired deck? I like the idea of extra aluminium for support. |
Yes. This is the ideal way to do it, and how I like to do it, but it takes extra measuring, and extra machine work, and most people just can't fathom a little extra time or money.
Brian
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Brian_e
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| Posted: Tue Oct 04, 2022 9:09 am Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| richparker wrote: |
| Brian_e wrote: |
The 3.5 raised deck is gonna cause you some extra issues.
Brian |
I have a CB White Rhino case with a +3.5mm deck. It’s built into a 8.1:1 compression 2275 with a Engle 110, CNC ported 044 heads and Weber IDF40s. This was built for a bus, runs like a scolded cat and produces excellent fuel economy.
I would have put a bigger cam in it, but it’s a bus engine. Is my beetle has a larger cam and it spins to the moon. As stated above, build it how you’re gonna use it. |
If you are after a giant deck height to run super low compression, this would be a good way to do it.
Brian
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jpaull
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Joined: February 22, 2005
Posts: 3466
Location: Paradise, Ca
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| Posted: Tue Oct 04, 2022 10:16 am Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| draksia wrote: |
| Glenn wrote: |
| draksia wrote: |
| I haven't gotten far enough to figure out what camshaft , lol |
Do that before thinking about compression ratio.
What length rods are you thinking? 5.4/5.5/5.6? |
I assumed 5.4 was the standard for an 82mm stroke |
This is the key right here. If you are buying rods anyhow, simply choose a longer rod and you can use the 3.5 or larger deck. You get a better rod ratio plus more cylinder support. More durable, less stress on the rotating assembly with the longer rod anyhow. That, and you dont need to machine any cylinders, just choose the right parts from the start.
But i know, everyone is determined to use 5.4 or 5.5 rods in every engine regardless of stroke, cause thats what most people do. I chose a 5.7 rod for my 3.5 deck. They were the same price as the 5.5's, and they were actually in stock lol.
http://carcraftstore.com/h-beam4340chromolyrods.aspx
82x5.4 = 1.67 Rod Ratio
82x5.7 = 1.77 Rod Ratio
69x5.4 = 1.99 Rod Ratio (Stock) |
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draksia
Samba Member
Joined: July 07, 2022
Posts: 14
Location: FL
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| Posted: Tue Oct 04, 2022 12:06 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| jpaull wrote: |
| draksia wrote: |
| Glenn wrote: |
| draksia wrote: |
| I haven't gotten far enough to figure out what camshaft , lol |
Do that before thinking about compression ratio.
What length rods are you thinking? 5.4/5.5/5.6? |
I assumed 5.4 was the standard for an 82mm stroke |
This is the key right here. If you are buying rods anyhow, simply choose a longer rod and you can use the 3.5 or larger deck. You get a better rod ratio plus more cylinder support. More durable, less stress on the rotating assembly with the longer rod anyhow. That, and you dont need to machine any cylinders, just choose the right parts from the start.
But i know, everyone is determined to use 5.4 or 5.5 rods in every engine regardless of stroke, cause thats what most people do. I chose a 5.7 rod for my 3.5 deck. They were the same price as the 5.5's, and they were actually in stock lol.
http://carcraftstore.com/h-beam4340chromolyrods.aspx
82x5.4 = 1.67 Rod Ratio
82x5.7 = 1.77 Rod Ratio
69x5.4 = 1.99 Rod Ratio (Stock) |
I am guessing running longer rods would result in an over all wider engine making the tin not fit well.
Are there any other issues I would run into? |
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jpaull
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Joined: February 22, 2005
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Location: Paradise, Ca
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 76940
Location: Sneaking up behind you
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| Posted: Tue Oct 04, 2022 4:01 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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My 2180 needed no tin mods and everything fits just fine with 5.4 rods and as41 case.
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"You may not get what you pay for, but you always pay for what you get"
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slalombuggy
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Joined: July 17, 2010
Posts: 9147
Location: Canada
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| Posted: Tue Oct 04, 2022 5:08 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| The 3.5mm decks are already going to make it wider so I see no problem running 5.5 rods and getting g a tighter deck to start. I wouldn't really worry about rod ratios. |
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txoval
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Joined: January 23, 2004
Posts: 3552
Location: The Woodlands, TX
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| Posted: Tue Oct 04, 2022 6:04 pm Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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Have you bought the pistons? Go with C pistons (33mm pin height) and you’ve made 2 of the 3.5mm up
Just need to do the math before ordering parts…once in hand, measure and fine tune as necessary |
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slalombuggy
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Posts: 9147
Location: Canada
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| Posted: Wed Oct 05, 2022 4:20 am Post subject: Re: 3.5 mm Raised Deck Engine Case / 92 or 94mm base |
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| txoval wrote: |
Have you bought the pistons? Go with C pistons (33mm pin height) and you’ve made 2 of the 3.5mm up
Just need to do the math before ordering parts…once in hand, measure and fine tune as necessary |
He needs to move the pistons up. Not down. "A" pistons would be better suited to what he needs |
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