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NJ John Samba Member
Joined: September 21, 2007 Posts: 2224 Location: HdG, MD & NJ
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Posted: Mon Aug 19, 2019 4:27 pm Post subject: Reshaping chamber help |
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I’ve had these years for a while. Stock bore, ported nicely, but fly cut a bunch. I want to add some cc’s to the chambers. I think I checked them once and it was in the low 30’s. I kinda want to use them for a 1600 turbo project or the next step for the turbo, machine in forged 88’s. Any input on chamber shape would be great. They have 7 fins.
_________________ 1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
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Pruneman99 Samba Member
Joined: February 22, 2012 Posts: 5013 Location: Oceanside
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Posted: Mon Aug 19, 2019 4:44 pm Post subject: Re: Reshaping chamber help |
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What CC will you need for the target compression ratio? For a turbo engine, I doubt you're going to get there with those. |
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Ebel Samba Member
Joined: June 07, 2015 Posts: 564 Location: New york
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Posted: Mon Aug 19, 2019 4:50 pm Post subject: Re: Reshaping chamber help |
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You won’t be taking 20ccs out of those heads easily. The compression would be around 14:1 with 30 cc and a turbo it won’t last long. Maybe if you run e85 it would be possible to use those heads and a turbo. I don’t know how much a hemi would gain. But stock chambers are a lot bigger then 30 cc. |
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clonebug Samba Member
Joined: January 29, 2005 Posts: 4027 Location: NW Washington
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Posted: Mon Aug 19, 2019 7:43 pm Post subject: Re: Reshaping chamber help |
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For 88mm P/C's you will need at least 52cc's to get around 8.0:1.
I have .062" deck on a stock untouched case using .010" shims under the barrels and 52cc heads. That gives me a 7.8:1 compression ratio. _________________
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Paul.H wrote: |
That one line on that chart is probably better info than you can get from this place in a month |
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FreeBug Samba Member
Joined: March 12, 2012 Posts: 4278 Location: deepest, darkest Switzerland
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Posted: Mon Aug 19, 2019 11:56 pm Post subject: Re: Reshaping chamber help |
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How many ccs do you need? If it was me, I'd concentrate on getting the ccs by removing material where it would help unshroud the upper side of the intake (leave the non-plug side alone) to increase flow there, as most of it goes through the bottom.
By going to 88s, you will get a bit more side clearance to enlargen the chamber, and you could unshroud the intake even more, getting the walls as concentric as you can. I use drill bits of increasing sizes to check around the perimeter of the valve for concentricity.
Looks like there is hardly any room to semi-hemi it, but maybe you could create an approximation of the non-plug side of the se-he, I don't see why it should work any less than on a full se-he. Maybe better because you could keep some squish?
Just throwing ideas out, others know more. |
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earthquake Samba Member
Joined: January 10, 2008 Posts: 3984 Location: SANDY VALLEY, NEVADA
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Posted: Tue Aug 20, 2019 12:20 am Post subject: Re: Reshaping chamber help |
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You could have them "Hemi" cut if any body still does it.
Casey _________________ 74 CLASS 11 LOOK-A-LIKE
69 DUNE BUGGY
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nsracing Samba Member
Joined: November 16, 2003 Posts: 9481 Location: NOVA
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Posted: Tue Aug 20, 2019 6:20 am Post subject: Re: Reshaping chamber help |
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For the turbo - just get a different set of heads and save those tight ones for street engines.
If you already removed fins, means it is too tight already. 20cc is a lot. That is half of the chamber you got now. Where are you gonna cut that out from? |
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[email protected] Samba Member
Joined: August 15, 2002 Posts: 4394 Location: Brew City
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Posted: Tue Aug 20, 2019 6:50 am Post subject: Re: Reshaping chamber help |
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NJ John wrote: |
I’ve had these years for a while. Stock bore, ported nicely, but fly cut a bunch. I want to add some cc’s to the chambers. I think I checked them once and it was in the low 30’s. I kinda want to use them for a 1600 turbo project or the next step for the turbo, machine in forged 88’s. Any input on chamber shape would be great. They have 7 fins.
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I don't say this often but there is NO WAY you can carve out enough CC's on chambers that are in the low 30's. If you were in the mid 40's and wanted to go to 50 something, that is possible but if you try grinding, you will change the entire shape/design of the chamber itself. Plus, heads for turbo normally have shortened guides, better seats, etc. Just buy a proper set of heads and sell those to an off road guy(they normally like chambers in the 30's) _________________ Please "LIKE" us on facebook to see what we are working on.
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NJ John Samba Member
Joined: September 21, 2007 Posts: 2224 Location: HdG, MD & NJ
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Posted: Tue Aug 20, 2019 10:01 am Post subject: Re: Reshaping chamber help |
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Thanks for the inputs. I thought it was a lost cause. I’ll save them for a n/a situation. There’s so many major fly cut heads out there. _________________ 1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage |
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BFB Samba Member
Joined: November 03, 2014 Posts: 1762
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Posted: Tue Aug 20, 2019 5:19 pm Post subject: Re: Reshaping chamber help |
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these were 42cc chambers that i opened up to 60 cc to get an 8:1 2276 , turbo.
funny thing was after i did this a buddy pointed out to me that some of the guys building boosted ls engines have been doing this to the heads. i was just being cheap and wanted to see if i could make it work |
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MURZI Samba Member
Joined: August 25, 2005 Posts: 5063 Location: Madisonville, La
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Posted: Tue Aug 20, 2019 5:23 pm Post subject: Re: Reshaping chamber help |
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Nothing wrong with running a ton of deck on a turbo engine either _________________ 62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam |
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FreeBug Samba Member
Joined: March 12, 2012 Posts: 4278 Location: deepest, darkest Switzerland
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Posted: Wed Aug 21, 2019 2:08 am Post subject: Re: Reshaping chamber help |
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richardcraineum wrote: |
these were 42cc chambers that i opened up to 60 cc to get an 8:1 2276 , turbo.
funny thing was after i did this a buddy pointed out to me that some of the guys building boosted ls engines have been doing this to the heads. i was just being cheap and wanted to see if i could make it work |
That's kinda heroic. |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7219 Location: Videbaek Denmark
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Posted: Wed Aug 21, 2019 3:32 am Post subject: Re: Reshaping chamber help |
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Also, IF you decide to go that route, deck height suddenly doesnt matter anymore because its all part of the chamber.
The downside is that you will loose A LOT of torque compared to normal wedge chambers, like 8%. |
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Pruneman99 Samba Member
Joined: February 22, 2012 Posts: 5013 Location: Oceanside
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Posted: Wed Aug 21, 2019 1:20 pm Post subject: Re: Reshaping chamber help |
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I'd be afraid of leaving too much space between the top of the piston and the top of the barrel. Especially in a turbo engine. Even if your running heads with no quench area. If your running hemi heads I'd set the "deck" at zero and keep the boom in the heads, and less in the cylinder. |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Wed Aug 21, 2019 2:26 pm Post subject: Re: Reshaping chamber help |
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Alstrup wrote: |
Also, IF you decide to go that route, deck height suddenly doesnt matter anymore because its all part of the chamber.
The downside is that you will loose A LOT of torque compared to normal wedge chambers, like 8%. |
bingo!!! you still should have some quench aeras!! but it's just a vw so why bother , bubba did it so it must work. |
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7549 Location: Santa Cruz
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Posted: Wed Aug 21, 2019 11:04 pm Post subject: Re: Reshaping chamber help |
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Maybe work up some dished pistons? _________________ Bus Motor Build
What’s That Noise?!? |
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NJ John Samba Member
Joined: September 21, 2007 Posts: 2224 Location: HdG, MD & NJ
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Posted: Thu Aug 22, 2019 1:47 pm Post subject: Re: Reshaping chamber help |
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I’ll probably not try to use them in a turbo application. The 1600 turbo will be the experimental and my first turbo. So my current heads will do.
I had a n/a 1641 with similar heads that ran 14’s in the quarter. But I hate having all these combos I my head and only half of the correct parts for each one of them. _________________ 1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage |
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sled Samba Member
Joined: February 16, 2005 Posts: 6179
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Posted: Thu Aug 22, 2019 3:59 pm Post subject: Re: Reshaping chamber help |
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I've heard and read guys say that quench and tight deck do not matter for a turbo. Not disputing this (as I've never built a turbo acvw) but how could it not matter when off-boost? a turbo street car spends the vast majority of its time off boost and wouldn't it be better for performance if it had tight deck/squish? as long as the compression is low enough to handle the extra boost...
at WOT and full boost I imagine its not as much of a factor, but up UNTIL that point it would be nice to have a snappy efficient engine as well? _________________ drive your split. |
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