Author Topic: 383 compression ratio  (Read 2674 times)

Offline 305chevy c-10

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383 compression ratio
« on: January 19, 2011, 08:57:28 PM »
using 5.7 rods on dished pistons .3.75 stroke .with.030 bore with EQ-CC170BA heads(170cc/64cc) and 650 holley ,performer intake and HEI distributor with a mild roller cam ......what kind of compression im possibly looking at .........87 pump gas ...and streetable
Heartbeat of America yesterday's cheverolet
18T5C10

Offline screamin86

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Re: 383 compression ratio
« Reply #1 on: January 19, 2011, 09:20:25 PM »
How much of a dished piston?
86 k10 lwb 4x4:350 .040 214/224 444/466 112lsa performer rpm 1406 lt's summit racing th350 2800stall
03 yukon xl:tint debadge full boltons
86 ta:lm7 hot cam boltons

Offline TexasRed

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Re: 383 compression ratio
« Reply #2 on: January 19, 2011, 11:47:01 PM »
yeah, kb pistons has a calculator on their website. I think with their kb 135 pistons and 64 cc chamber heads, I was at a compression ratio of 9.5:1. And that's with a LOT OF dish. I haven't tried 89 octane yet, but I might, been running 93 and getting 10 mpg.

Offline 305chevy c-10

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Re: 383 compression ratio
« Reply #3 on: January 22, 2011, 06:32:18 PM »
has anyone used these heads before  EQ-CC170BA heads(170cc/64cc)........trying to find a compression chart for them .................so i will know what type piston to run flat,dished,or domed 2vr or 4vr ........want the best for 87 gas
Heartbeat of America yesterday's cheverolet
18T5C10

Offline Blue 82

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Re: 383 compression ratio
« Reply #4 on: January 22, 2011, 06:50:54 PM »
With the piston .010" below the deck, and a .039" head gasket,
a dish or d-cup of -19.5cc will put you at 9.36:1

If you choose not to deck the block and run the slug .025" down
you will be at 9.09:1 (with the same specs above)

http://www.csgnetwork.com/compcalc.html

I'm supposing the EQ-CC170BA heads are the Engine Quest hybrid heads?
Why not call EQ and see what they recommend?

Some heads like a reverse dome piston


Some heads run better with a full dish
« Last Edit: January 22, 2011, 07:03:49 PM by Blue 82 »
82 stepside 2wd 355/th350/3.08 posi

Offline 305chevy c-10

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Re: 383 compression ratio
« Reply #5 on: January 22, 2011, 08:12:26 PM »
is 10.7.1 good compression ratio for 87 oct.........where do i need to stay for this
Heartbeat of America yesterday's cheverolet
18T5C10

Offline 1980c10

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Re: 383 compression ratio
« Reply #6 on: January 22, 2011, 11:40:18 PM »
is 10.7.1 good compression ratio for 87 oct.........where do i need to stay for this

no. way too much compression

Just finished my 350 with vortech #062 64cc, with flat top pistons with a mild cam about 9.7 to 1 CR
runs great on the dyno with 91 octane. probably could run 87 without a problem.
btw running a 670avenger(increased jets to f68 r72) added (7-8 hp) and performer intake, timing: 31 degrees adv.
I also added a 1" open spacer between the carb and intake; this evened out the A/F mixture between left and right(added 9 hp).

I am sure these changes will hold true in your build or at least give you a baseline, especially the spacer.

I would run flat tops; I don't think you'll have a problem with 91 and may be able to run 87, if you want to be sure then use the dished you'll probably get about a 9.2-1 CR

btw final #'s on my engine were 393 hp@5400 and 432 tq@4300

either way you are going to end up with a torque monster





Offline 305chevy c-10

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Re: 383 compression ratio
« Reply #7 on: January 30, 2011, 08:29:03 AM »
ok will go with dished .....if i end up with a torque monster ..........my goal has been reached
 will give EQ a call to be safe
Heartbeat of America yesterday's cheverolet
18T5C10

 


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