Compression ratios...
#4
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I suspect you would like to read it too, sorry, that probably wasnt very helpful given that no doubt you dont have a budget for building 20 YB's to run back to back and datalog, lol
I suspect others will find even basic info like the fact that as CR increases timing needs to decrease etc.
I suspect others will find even basic info like the fact that as CR increases timing needs to decrease etc.
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you could delve into combustion chamber and piston designs, squish areas and how they affect things...Slightly off c/r subject aqactly but its related so might be worth a mention.
Also why it allows you to run more boost....how it affects det and what det actually is...
just some ideas...probably all shit but then again thats why you're writing not me![Surprised](https://passionford.com/forum/images/smilies/bigcry.gif)
Dan
Also why it allows you to run more boost....how it affects det and what det actually is...
just some ideas...probably all shit but then again thats why you're writing not me
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Dan
Last edited by SillyFezzaMk1; 25-02-2008 at 01:29 PM.
#11
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It deffo needs some explanation for people about the current "oooh, high compression is mint, why dont we all run the usual 35psi 600bhp spec just with 9:1 compression and it will be fantastic and perfect on pump fuel" myth.
Need to explain, though its going off on a tangent a little, that you need to spec engines as a whole, and its not just comp ratio.
Ie a 250bhp per litre ideal spec pump fuel low compression turbo engine and a 250bhp per litre ideal spec pump fuel high compression turbo engine will have a very different turbo/cam/etc etc spec.
Need to explain why upping the compression a bit doesnt make up for lowering the boost a bit, if all else is equal.
Need to explain the effects, or lack of, of compression on boost threshold, esp in comparison to cam and turbo changes.
Basically it should be all about dispelling the common myths etc IMO.
Need to explain, though its going off on a tangent a little, that you need to spec engines as a whole, and its not just comp ratio.
Ie a 250bhp per litre ideal spec pump fuel low compression turbo engine and a 250bhp per litre ideal spec pump fuel high compression turbo engine will have a very different turbo/cam/etc etc spec.
Need to explain why upping the compression a bit doesnt make up for lowering the boost a bit, if all else is equal.
Need to explain the effects, or lack of, of compression on boost threshold, esp in comparison to cam and turbo changes.
Basically it should be all about dispelling the common myths etc IMO.
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I know asbsolutely sweet FA about it Stu so will be beneficial for me to read it learn something, i'd like to understand better how the torque of the engine and 'lag' of the turbo are affected by higher and lower CR's ![Big Grin](https://passionford.com/forum/images/smilies/icon_biggrin.gif)
Thanks
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Thanks
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#27
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is this going to be specifically for the yb then or will it cover just the basics around cr?
if it's the later what about a little box out about deisels and how they have different piston shapes etc?
also the differences a head gasket will make if you are trying to calculate your cr when every little bit counts?
if it's the later what about a little box out about deisels and how they have different piston shapes etc?
also the differences a head gasket will make if you are trying to calculate your cr when every little bit counts?
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i know a question id like answered, if certain compression ratio on a turbocharged engine was cusing pinking, if you dropped it slightly less would it have any effect on the pinking? strange question, top secret im just hoping it works as i know too high compression can cause pinking.
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Stu
Intrested in Ratios, i have always been one for standard ratios, i must admit i did struggle to run my old sierra twinky at 1 Bar boost with 10.5:1 compression, but now im YB with standard compression, intrested to read on whats a viable BHP output on standard compression ratio, and what compression ratios suit what horsepower, i know there are many factors that surround this, but a ball park would be good, as we seem to get people on here running 6.9:1 ratio for say 500bhp, and 7.2:1 for 450bhp, when you speak to M Shead and others he is quite happy with standard comp into early to mid 400bhp, for 430bhp he was happy with standard comp, so reasons why people go for 7.2:1
Thanks, for the Info
Also intrested in gas flowed heads and thoughts on what level of porting is required
Intrested in Ratios, i have always been one for standard ratios, i must admit i did struggle to run my old sierra twinky at 1 Bar boost with 10.5:1 compression, but now im YB with standard compression, intrested to read on whats a viable BHP output on standard compression ratio, and what compression ratios suit what horsepower, i know there are many factors that surround this, but a ball park would be good, as we seem to get people on here running 6.9:1 ratio for say 500bhp, and 7.2:1 for 450bhp, when you speak to M Shead and others he is quite happy with standard comp into early to mid 400bhp, for 430bhp he was happy with standard comp, so reasons why people go for 7.2:1
Thanks, for the Info
Also intrested in gas flowed heads and thoughts on what level of porting is required
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#36
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I have on a number of occasions bought the mag for your article alone! My reasons for using the site are the same, apart from retro escorts, im not a huge ford fan, but the tech level on here is well worth being around for!