Compression #'s and Compression Raito.. 1 in the same?
Thread Starter
Honda-Tech Member
Joined: Aug 2001
Posts: 8,613
Likes: 1
From: Naples, Fl, USA
Compression #'s and Compression Raito.. 1 in the same?
Ok, I know what the CR is (volume of chamber at BDC vs. TDC) and what compression is (amount of air in psi compressed in the chamber). Now to me it would make sense that as the ratio goes up, the actual compression # would go up too (same amount of air, less area to fit it = higher compression #'s), am I right or way off??
Honda-Tech Member
Joined: May 2001
Posts: 5,089
Likes: 1
From: Trinidad, W.I.
Re: Compression #'s and Compression Raito.. 1 in the same? (GSRwBOOST)
So by that fact, would it be correct to assume a motor with a 9.0:1 CR would yield notably lower compression numbers than one that has a 10.0:1 CR ?
Eg: 9.0:1= 180's and 10.0:1= 210's <--- comp numbers used as an example
X2
Eg: 9.0:1= 180's and 10.0:1= 210's <--- comp numbers used as an example
X2
Honda-Tech Member
Joined: Jun 2001
Posts: 8,120
Likes: 3
From: Irvine, CA, usa
Re: Compression #'s and Compression Raito.. 1 in the same? (X2BOARD)
Not so. Lot of other factors involved..duration of cams, overlap of cams, cam timing, condition of valves and springs, ring seal, leaking head gasket, amount of carbon on pistons and valves, etc.
It even makes a difference if you do the test with the throttle body open or closed.
It even makes a difference if you do the test with the throttle body open or closed.
Honda-Tech Member
Joined: Jun 2001
Posts: 2,763
Likes: 2
From: Dark Aether
Re: Compression #'s and Compression Raito.. 1 in the same? (VTC_CiViC)
All things being equal, compression #'s and compression ratio will rise together. As Earl pointed out though, things are not always equal. I've seen as much as 20 psi variance on the same engine using different gauges. Additionally, using cam gears to dial in/dial out overlap can change compression numbers, too.
Sonny
Sonny
Honda-Tech Member
Joined: May 2001
Posts: 5,089
Likes: 1
From: Trinidad, W.I.
Re: Compression #'s and Compression Raito.. 1 in the same? (Sonny)
Understandable that there are multiple factors involved in reading a motor's compression, but as a general rule, engines with higher CRs will typically have higher compression readings than engines with lower CRs, yes ?
X2
X2
Trending Topics
Honda-Tech Member
Joined: Jun 2001
Posts: 8,120
Likes: 3
From: Irvine, CA, usa
Re: Compression #'s and Compression Raito.. 1 in the same? (X2BOARD)
No, not even as a general rule because of camshafts. But, everything being equal in the same motor, the 11-1 cr should give a higher compression # than the 10-1.
Thread Starter
Honda-Tech Member
Joined: Aug 2001
Posts: 8,613
Likes: 1
From: Naples, Fl, USA
Re: Compression #'s and Compression Raito.. 1 in the same? (earl)
No, not even as a general rule because of camshafts. But, everything being equal in the same motor, the 11-1 cr should give a higher compression # than the 10-1.
Right.. in other words, all other things equal, a motor with a higher CR will yield a higher compression number
Thanks guys.. X2, I'll take delivery of those Z3 fenders tomorrow thanks
Honda-Tech Member
Joined: May 2001
Posts: 5,089
Likes: 1
From: Trinidad, W.I.
Re: Compression #'s and Compression Raito.. 1 in the same? (VTC_CiViC)
No, not even as a general rule because of camshafts. But, everything being equal in the same motor, the 11-1 cr should give a higher compression # than the 10-1.
Right.. in other words, all other things equal, a motor with a higher CR will yield a higher compression number
Thanks guys.. X2, I'll take delivery of those Z3 fenders tomorrow thanks
Right.. in other words, all other things equal, a motor with a higher CR will yield a higher compression number
Thanks guys.. X2, I'll take delivery of those Z3 fenders tomorrow thanks
Sorry VTC, they Z3's are currently on national backorder. I can, howver, deliver the indiglo 'racing' pedals that you ordered..... I will package them in the UPS box with your MaDSKilLs cucullios....
We take Visa, MasterCard and RicersClub with picture ID only.
Thread
Thread Starter
Forum
Replies
Last Post
