 Compression Ratio, Too High...Too Low ??? |
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| 2-OH! |
 Sep 6 2007, 05:44 PM
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Senior Member  Group: Members Posts: 552 Joined: 17-October 03 From: Santa Clarita, Kalifornication Member No.: 1,253  |
Ok folks,
We just finished rebuilding the motor...94mm pistons and cylinders to match...71mm stroke...but old 1.7 case...CC'd the heads and come up with 44 cc's per cylinder... Do the calculations and we come out with 1971 cc's...Great !!! But, The problem is the compression ratio is now 10.64 to 1... The question of the day: Should I take the cylinders and heads back off and shim them to get a little relief...Probably not going to get much...Might knock it down to 10 or 9.75 (if I'm lucky)... DO NOT want this thing to clatter and diesel on me when I get it back together... OK, let me have it...What are your thoughts ??? 2-OH! |
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Posts in this topic
2-OH! Compression Ratio Sep 6 2007, 05:44 PM
yeahmag Way, way to high. You willl need some big honking ... Sep 6 2007, 05:57 PM mike373 Only if you plan on running jet fuel.... But seri... Sep 6 2007, 05:58 PM
orange914
Only if you plan on running jet fuel.... But ser... Oct 17 2007, 09:05 PM ConeDodger
Ok folks,
We just finished rebuilding the motor... Sep 6 2007, 05:58 PM swl slight highjack:
Educate me - how does the cam get... Sep 6 2007, 06:03 PM swl should have thought about it more - has to do with... Sep 6 2007, 06:05 PM yeahmag Long story short...
A high duration cam bleeds of... Sep 6 2007, 06:12 PM 2-OH! Using a Web Cam 73 Grind...Still running D-Jet...
... Sep 6 2007, 06:15 PM Cap'n Krusty
Using a Web Cam 73 Grind...Still running D-Jet...... Sep 6 2007, 11:23 PM yeahmag My guess would be 8:1 on that cam. What did you he... Sep 6 2007, 06:21 PM jd74914 Ok, that compression is definitely too high for D-... Sep 6 2007, 07:15 PM 2-OH! I agree with Aaron above...
Somebody check my mat... Sep 6 2007, 09:43 PM Twystd1 Whats your deck height?
I.E. From top of piston t... Sep 6 2007, 10:03 PM 2-OH! Thanks Clayton...
The way I measured it was with ... Sep 6 2007, 10:14 PM Borderline My calcs:
Cyl vol: 492.7 cc
head vol: 44 cc
d... Sep 6 2007, 10:59 PM Brett W Toss the Djet, buy a nice cam Web 163/86b, or simi... Sep 7 2007, 12:24 AM Twystd1 What was the deck height measurement?
CCC Sep 7 2007, 12:28 AM Bleyseng
What was the deck height measurement?
CCC
yeah... Sep 7 2007, 09:34 AM 2-OH! Thanks for the help guys...
Looking at my notes, ... Sep 7 2007, 09:40 AM rhodyguy rick, was your case 0 decked during the machining ... Sep 7 2007, 09:49 AM Jake Raby Ok, How the hell did you get a 44cc chamber?? Are ... Sep 7 2007, 11:22 AM Brett W Chamber volume can only be calculated by measuring... Sep 7 2007, 11:51 AM andys Rick,
I just now read this thread. I too question... Sep 7 2007, 12:01 PM 2-OH! Thanks Andy, good great idea...I would like to fig... Sep 7 2007, 02:44 PM Twystd1 Bring both of your heads to GAF.
I have a burrete... Sep 7 2007, 04:13 PM 2-OH! Clayton,
What a great offer, many thanks...Let me... Sep 7 2007, 08:52 PM Twystd1 You can also use a graduated horse serum syringe (... Sep 7 2007, 09:52 PM Twystd1 We now know the problem.
And we have a possible ... Sep 9 2007, 07:16 PM Jake Raby How many ccs were they???? A hemi cut might be in ... Sep 10 2007, 08:19 AM Heeltoe914 Clayton:
I would say from seeing this motor a... Sep 10 2007, 12:07 PM brer Lets see the aforementioned heads.
I'm curiou... Sep 10 2007, 12:41 PM Heeltoe914
Lets see the aforementioned heads.
I'm curio... Sep 10 2007, 01:40 PM Jake Raby Feel free to send me the parts if you want... do t... Sep 10 2007, 01:22 PM 2-OH! I gotta tell you, after spending time at the GAF w... Sep 10 2007, 02:07 PM Twystd1 A butt ugly person from NARP has volunteered a com... Sep 10 2007, 02:34 PM andys Agreed, the 2-OH car is beautiful and deserves a d... Sep 10 2007, 03:40 PM brer If you ever come down this way bring those boat an... Sep 10 2007, 03:56 PM Brett W Just put the heads on and run them. Don't wor... Sep 10 2007, 11:16 PM Joe Ricard Sometimes you just got to wonder what people are ... Sep 11 2007, 06:41 AM type11969 What about using some dished pistons to bring the ... Sep 11 2007, 07:19 AM Joe Ricard This would also kill the efficiency. There would b... Sep 11 2007, 07:48 AM type11969 I dunno if I agree with that, I'm pretty sure ... Sep 11 2007, 08:29 AM Joe Ricard Bus piston dish is pretty huge. and pretty deep. ... Sep 11 2007, 10:04 AM Jake Raby It'll take 8-12cc of piston dish to get the CR... Sep 11 2007, 10:09 AM davep Hmm, I have a set of bus pistons in a 2.0 motor ju... Sep 11 2007, 10:21 AM Jake Raby Its a good "Band aid" for his issue. Sep 11 2007, 10:27 AM Twystd1 We need solutions. Not bagging on the previous bui... Sep 11 2007, 09:05 PM Brett W What's the deck height? You can't do it r... Sep 11 2007, 10:06 PM Twystd1 OK...
Lets assume for a moment that we are using ... Sep 11 2007, 10:40 PM Heeltoe914 I think (sometimes not very well) that we can make... Sep 11 2007, 11:44 PM Jake Raby Try it.. It tried it for almost 3 years off an on ... Sep 12 2007, 12:05 AM Heeltoe914
Try it.. It tried it for almost 3 years off an on... Sep 12 2007, 04:27 PM type11969 Hey, Bus pistons were my idea!! FYI I am r... Sep 12 2007, 09:08 AM Brett W .030 is too tight a deck for the stock engine with... Sep 12 2007, 09:18 AM Bleyseng I my own testing, changing the fuel pressure from ... Sep 13 2007, 08:42 AM Jake Raby The problem with higher CR and stock FI is what oc... Sep 13 2007, 09:46 AM Heeltoe914
The problem with higher CR and stock FI is what o... Sep 13 2007, 10:25 AM type11969 brake specific fuel consumption
fuel consumption ... Sep 13 2007, 10:28 AM Heeltoe914 That helped :confused: just ... Sep 13 2007, 10:42 AM type11969 it is a measure of efficiency, its how much fuel y... Sep 13 2007, 10:48 AM  |
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