Forced Induction Superchargers | Turbochargers | Intercoolers
View Poll Results: Whats the best CR to have for 15-22 pounds of boost?
11:1
8
2.87%
10.5:1
4
1.43%
10:1
20
7.17%
9.5:1
59
21.15%
9:1
67
24.01%
8.5:1
95
34.05%
8:1
26
9.32%
Voters: 279. You may not vote on this poll

CR for big boost...

Old Jun 5, 2008 | 11:07 AM
  #161  
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Originally Posted by Rock_Daddy
I bet alot of people are not actually reading the first post before they vote.

"What would the ideal CR be for a built motor to withstand a high amount of boost (say 15-22#'s), for maximum power with race gas?
"

If we are talking max power with race gas I can't see anyone voting for 8 or 8.5:1 for the boost range listed. IMO

The never ending debate continues!
If they don't read the post, then how would they know what they are voting on? The info was right there, and it probably surprised many who would go with that CR for the given conditions.
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Old Jun 5, 2008 | 11:04 PM
  #162  
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[QUOTE=CALL911;9499633]If they don't read the post, then how would they know what they are voting on?
QUOTE]

are you really asking that question? the general public has been doing that for years
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Old Jun 6, 2008 | 05:55 AM
  #163  
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I'm not asking anything. I'm just saying the info was right there the whole time.
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Old Jun 6, 2008 | 06:24 AM
  #164  
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Well the poll lable which most read doesn't list the same info as the question in the first post. The first post specifies race gas but the poll itslef does not include that import bit of info. So if you read the poll title you would probably assume pump gas and pick based on that. If you read the post it say most power on race gas which I bet most would pick highter if they read that. I find it hard to believe anyone would think 8:1 at lets say the low of 15psi makes more power then a highter compression at the same psi when using race gas to support it.
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Old Jun 6, 2008 | 08:06 AM
  #165  
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Originally Posted by Rock_Daddy
Well the poll lable which most read doesn't list the same info as the question in the first post. The first post specifies race gas but the poll itslef does not include that import bit of info. So if you read the poll title you would probably assume pump gas and pick based on that. If you read the post it say most power on race gas which I bet most would pick highter if they read that. I find it hard to believe anyone would think 8:1 at lets say the low of 15psi makes more power then a highter compression at the same psi when using race gas to support it.
ding ding ding we have a winner!
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Old Jun 6, 2008 | 04:11 PM
  #166  
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Thats up to them to read the post and get the facts. I can't help it if people don't.
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Old Jun 9, 2008 | 05:37 PM
  #167  
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Originally Posted by CALL911
Thats up to them to read the post and get the facts. I can't help it if people don't.
your right, it's not your fault that people are voting based on information not relavent to the poll. so anybody reading the poll as legit info would be getting false information. which as we all know is what helps the internet grow
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Old Jun 9, 2008 | 06:29 PM
  #168  
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Originally Posted by dman
your right, it's not your fault that people are voting based on information not relavent to the poll. so anybody reading the poll as legit info would be getting false information. which as we all know is what helps the internet grow
There's no way you can proove either way that people read the info or not. For all we know all of them read the facts before they voted, or none for that matter either.
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Old Jun 9, 2008 | 07:21 PM
  #169  
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Originally Posted by CALL911
There's no way you can proove either way that people read the info or not. For all we know all of them read the facts before they voted, or none for that matter either.
exactly my point.
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Old Jun 9, 2008 | 07:46 PM
  #170  
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Sounds like the poll and the first post should have been asking the same question.

Do Over!
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Old Jun 9, 2008 | 08:24 PM
  #171  
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Plus 1 for 9.5/10.0. I make 566RWHP on my stock heads and bottom end at 9psi (pump gas/no meth).... when i build the bottom end this winter I sure as hell am not going to lower the compression just so I can turn the blower up to make the same power I was with the stock motor. The only reason I have a boost gauge at all is to check for belt slip and/or boost leaks, other than that its just for looks.
My plan is to build a bottom end with good rods and flat tops, keep my mystery cam, slap some sorta head on it and turn the blower (D1) as fast it will go. Maybe run some meth and let my tuner (slowhawk) take care of getting it to hold together. Should make adequate power.

I think that the difference in opinions comes for the blower vs turbo deal, its real easy to turn up a turbo and make more boost, centri cars its not so easy with most setups.
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Old Jul 7, 2008 | 01:39 PM
  #172  
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I just got my new valves and cam-when it's all together my NEW CR should come out to a calculated 10.8.
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Old Jul 7, 2008 | 06:38 PM
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Originally Posted by eb02z06
I just got my new valves and cam-when it's all together my NEW CR should come out to a calculated 10.8.
giggidy giggidy
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Old Jul 8, 2008 | 09:10 AM
  #174  
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i thought i read somewhere in a vette magazine where the new supercharged Z06 has 10.7 compression? was that just a typo in the stats listed?
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Old Jul 8, 2008 | 10:24 AM
  #175  
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Originally Posted by dman
i thought i read somewhere in a vette magazine where the new supercharged Z06 has 10.7 compression? was that just a typo in the stats listed?
I wouldnt think it was a typo. A positive displacement blower likes compression.

Most guys think that all FI setups require a low CR, not always the case.


Derek
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Old Jul 21, 2008 | 08:42 PM
  #176  
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The only people that provided any real world numbers, whether they are dyno or track, are the guys rinnigh high compression. Everyone else that chooses low compression states that they "feel" it is safer and better. The whole low compression vs. high compression reminds me of the small cam vs. big cam. The obvious winner of the camdebate was that small cams can make amazing power and big cam guys wouldnt want to accept it. Seems to be the same with the low compression guys. They dont want to accept the fact that they could have made more power with higher compression and not have to spin a bigger blower/turbo in order to achieve the higher boost.
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Old Jul 22, 2008 | 07:08 AM
  #177  
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Originally Posted by Oh4GTO
The only people that provided any real world numbers, whether they are dyno or track, are the guys rinnigh high compression. Everyone else that chooses low compression states that they "feel" it is safer and better. The whole low compression vs. high compression reminds me of the small cam vs. big cam. The obvious winner of the camdebate was that small cams can make amazing power and big cam guys wouldnt want to accept it. Seems to be the same with the low compression guys. They dont want to accept the fact that they could have made more power with higher compression and not have to spin a bigger blower/turbo in order to achieve the higher boost.
Actually, it's been proven multiple times that you can still make more power going to a larger cam even when boosted, that's not to say you can't make great power with a small cam, your just leaving some on the table. This is all within reason, I'm not saying the larger you go the more power you get, you can always go too far but say using a stock cam and then upgrading to a mid size cam, yes the right mid size cam is going to make more power. Then going from mid size to large, yes the large IS going to make more power as long as it's the proper selection.
The same goes for high comp vs low. You can make great power with low comp, your just leaving some on the table and it seems most believe the power gain isn't worth the added risk of higher compression.
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Old Jul 22, 2008 | 07:29 PM
  #178  
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Agree with above statement. Higher CR with high boost will equal more power. No one is arguing that fact. The argument is if doing that is safe. Those that have done it for a few months or a few thousand miles will probably argue "yeah, its safe and the best way to go". Until enough abuse is done, and enough miles have passed and they are looking in the for sale section for parts for a new engine. If the setup is high boost with low CR, you will be safe every time for years and a ton of miles.

It seems to me you make a judgement call. You either roll the dice, and make a few more ponies at the rear wheels all the time not knowing if your next WOT will be the engines last. Or, you shoot for a few less ponies at the rear wheels sleeping easy at night knowing your engine can take repeated WOT runs with high boost safely for years to come.

The poll clearly shows what the majority have decided.
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Old Jul 23, 2008 | 09:43 AM
  #179  
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Originally Posted by CALL911
Agree with above statement. Higher CR with high boost will equal more power. No one is arguing that fact. The argument is if doing that is safe. Those that have done it for a few months or a few thousand miles will probably argue "yeah, its safe and the best way to go". Until enough abuse is done, and enough miles have passed and they are looking in the for sale section for parts for a new engine. If the setup is high boost with low CR, you will be safe every time for years and a ton of miles.

It seems to me you make a judgement call. You either roll the dice, and make a few more ponies at the rear wheels all the time not knowing if your next WOT will be the engines last. Or, you shoot for a few less ponies at the rear wheels sleeping easy at night knowing your engine can take repeated WOT runs with high boost safely for years to come.

The poll clearly shows what the majority have decided.
so your saying if you run a high comp/high boost combo on the ragged edge it won't last. but if you run a low comp/high boost combo on the ragged edge it will last for years and years? you are very wrong. The term "safe" that you use does not only apply to low comp set ups. It applies to EVERY set-up. If you tune for safety then you can expect your combo to live a long healthy life. If either set-up is tuned on the edge then they both have equal chance of blowing up. Detonation is the killer in either set-up. I've seen Plenty of blown headgaskets on low comp FI engines.

Again with the poll. if every person that took the poll had to pass a knowledge test based on engine dynamics most wouldn't have had a chance to vote. Lots of people vote based on "what they read". that doesn't make it true
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Old Jul 23, 2008 | 12:16 PM
  #180  
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Originally Posted by dman
so your saying if you run a high comp/high boost combo on the ragged edge it won't last. but if you run a low comp/high boost combo on the ragged edge it will last for years and years? you are very wrong. The term "safe" that you use does not only apply to low comp set ups. It applies to EVERY set-up. If you tune for safety then you can expect your combo to live a long healthy life. If either set-up is tuned on the edge then they both have equal chance of blowing up. Detonation is the killer in either set-up. I've seen Plenty of blown headgaskets on low comp FI engines.

Again with the poll. if every person that took the poll had to pass a knowledge test based on engine dynamics most wouldn't have had a chance to vote. Lots of people vote based on "what they read". that doesn't make it true

Who said both were on the raged edge? This is assuming that both cars (both the high CR one, and the low CR one) is properly setup with a good tune, and fuel system, even with supporting mods needed like intercoolers, and even race gas or methanol injection. The low CR will keep it further away from detonation, every time, period. That is why it will last longer, and take more. High CR is not meant for high boost applications. Look at any high dollar fast FI car in the FI section like MighTyMouse (article in GMHTP mag), or even NastyNate. Both are running extremly fast FI cars with lots of boost, but they are not at a high CR.

As for the poll, if you are saying just because a lot of people voted the way you didn't, does not mean they are all wrong. It just means that the majority voted that way. If you are saying most people on here don't know what they are talking about, then why are we having this conversation in the first place? Because if that is a given, then no ones opinion matters.
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