Notices
Engine Swaps, Tech & Tuning Swaps, N/A Performance, Forced Induction, Engine Management, & Troubleshooting

Supercharger and Compression Ratio

Thread Tools
 
Old 11-04-2004, 01:15 PM
  #1  
MoBiX
İŞŘs!
Thread Starter
 
MoBiX's Avatar
 
Join Date: Nov 2004
Location: Greenville, South Carolina
Posts: 64
Likes: 0
Received 0 Likes on 0 Posts
Default Supercharger and Compression Ratio

Does compression need to be as low with a supercharger as with a turbo?
Old 11-04-2004, 06:14 PM
  #2  
EX-R
Registered User
 
EX-R's Avatar
 
Join Date: Aug 2004
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Default

as low well on much boost are you gonna run you can easily run 12 psi of boost with 11.5:1 forged piston with a turbo so its not that low anyway
Old 11-04-2004, 07:57 PM
  #3  
Provocateur
On permanent hiatus
 
Provocateur's Avatar
 
Join Date: Jul 2004
Location: A forum with actual tech
Posts: 9,716
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by EX-R
as low well on much boost are you gonna run you can easily run 12 psi of boost with 11.5:1 forged piston with a turbo so its not that low anyway
Yeah if detonation is non-existent. Also the rods and rod bolts need to be upgraded as well to play it safe.
Old 11-04-2004, 09:49 PM
  #4  
dubcac
I
 
dubcac's Avatar
 
Join Date: Jan 2001
Location: Westside til I die
Posts: 56,525
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by EX-R
as low well on much boost are you gonna run you can easily run 12 psi of boost with 11.5:1 forged piston with a turbo so its not that low anyway
If it's tuned right, maybe. I wouldn't run that much compression under boost on pump gas. Boost is boost, whether it's from a turbo or SC, and you should make similar builds.
Old 11-05-2004, 05:05 PM
  #5  
EX-R
Registered User
 
EX-R's Avatar
 
Join Date: Aug 2004
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Default

I have not tried what I wrote but CP pistons claim that their 11.5:1 CR pistons used with proper rods with the rightfuel timing ( that means the gas burns instead of explodes) well you can manage an RSX (for example) with the Forced Induction + Nitrous Oxyde System that means , depending on whatever you did put under the hood, you can easily run 10+ psi when used with the right pistons, valve springs rods and all the mess.. but if you wanna go less than 10 pound then dont even be afraid of the result, your honda engine will handle it easily
Old 11-05-2004, 05:10 PM
  #6  
EX-R
Registered User
 
EX-R's Avatar
 
Join Date: Aug 2004
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Default

But to answer the initial question... Boost is boost and the more boost you put on an already high compression ratio the most dangerous it gets but give us an idea of what is a low CR for you because IMO 9:1 is a realllllly really low CR and if you read modified mag, they tuned an S2k with I dont remember how much boost ( I think its over 20 or around that wich is a lot) they used 9:1 CR forged pistons and I guess you are not gonna make a 600 hp car of your honda so 10-11 :1 CR is low enough to handle most of the usual boost we like! hope it helped.. for more info try something on turbo magazine web site they might have a good idea
Old 11-06-2004, 12:36 AM
  #7  
MoBiX
İŞŘs!
Thread Starter
 
MoBiX's Avatar
 
Join Date: Nov 2004
Location: Greenville, South Carolina
Posts: 64
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks!
Old 11-06-2004, 09:57 AM
  #8  
dubcac
I
 
dubcac's Avatar
 
Join Date: Jan 2001
Location: Westside til I die
Posts: 56,525
Likes: 0
Received 0 Likes on 0 Posts
Default

lol...if you wanna run 11-11.5:1 compression with boost in a street car, go right ahead. Have fun tuning it for pump gas.
Old 11-06-2004, 10:23 PM
  #9  
Provocateur
On permanent hiatus
 
Provocateur's Avatar
 
Join Date: Jul 2004
Location: A forum with actual tech
Posts: 9,716
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by EX-R
I have not tried what I wrote but CP pistons claim that their 11.5:1 CR pistons used with proper rods with the rightfuel timing ( that means the gas burns instead of explodes) well you can manage an RSX (for example) with the Forced Induction + Nitrous Oxyde System that means , depending on whatever you did put under the hood, you can easily run 10+ psi when used with the right pistons, valve springs rods and all the mess.. but if you wanna go less than 10 pound then dont even be afraid of the result, your honda engine will handle it easily
That is the most rediculous and misleading advice ever. Don't bump the compression ratio when boosting, lower it unless you plan on putting race fuel and race fuel only in your car.
Old 11-07-2004, 09:53 AM
  #10  
EX-R
Registered User
 
EX-R's Avatar
 
Join Date: Aug 2004
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Default

Yeah but if you lower compression ratio too low you loose low and mid-range rpm power and for a daily car well don't know I am not always running my car at 5-7k rpm

and guys in your opinions, by saying that a too high compression ratio would need race fuel.. what CR would you use then just give me an idea

An RSX type S comes stock with 11.0:1 compression ratio and you can run a greddy turbo on it at 8 psi ( stock suggested boost) without any problem so I don't understand the fact that going 11.5:1 with forged pistons would be that bad (when used with the right valve springs and rods).. Maybe I'm wrong tell me what u think



All times are GMT -8. The time now is 01:23 AM.