comp ratio

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Anonymous

Guest
What the best comp ratio and Y

I've been told that for a turbo car running over 350 should be around 7:2:1
 
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Anonymous

Guest
Datsun500R said:
What the best comp ratio and Y

I've been told that for a turbo car running over 350 should be around 7:2:1
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you would lose a bucket load of torque/driveability with such a low comp ratio but,you`d be able to run shed loads of boost eg 2bar+

it`s a balancing act between torque production,desired boost levels and onset of detonation.with high comp ratios you tend to run with lower boost and may have to continually add octane booster or race fuel etc.

i`ve got 2 bar on approx 8:1 using optimax fuel only but power doesn`t start to come in until 3k approx.i`m giving serious thought to upping the comp ratio slightly to try and get a bit more torque lower down the rev range.
 
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Anonymous

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si.. said:
you've gotta be kiddin :shock: :lol:
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i know you thought it was fast but it only has torque over a 3-3.5k wide rev range.didn`t you notice the delay between pedal hitting carpet and light speed :lol: :lol:
 
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Edd

Guest
oap-r said:
didn`t you notice the delay between pedal hitting carpet and light speed :lol: :lol:
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sounds like you need to get yourself a more efficient turbo :wink:
may i suggest an HKS GT3037S or GT3240 :p :p :p
 
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Si..

New Member
i know you thought it was fast but it only has torque over a 3-3.5k wide rev range.didn`t you notice the delay between pedal hitting carpet and light speed
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yeah i noticed it, but the intensity of when it did kick in more than made up for it. :twisted:

i know what your getting at tho, considering i was only in it a short while (thank f**k) it wasnt something i'd notice like you would driving it all the time.

so are you running the pistons that came with the 2.2, what comp are they?
 
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Anonymous

Guest
Edd said:
sounds like you need to get yourself a more efficient turbo :wink:
may i suggest an HKS GT3037S or GT3240 :p :p :p
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may i suggest you fcuk off :lol: :lol: :lol:
once my mapping is complete you wont see which way i went :twisted:
 
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Edd

Guest
Well we will see Sir oap-r, we know who's car has the most proven power so far :wink:

i hope your going to get it mapped for a bit more boost :twisted: :twisted: to suit your nice new clutch :wink: :twisted:
 
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Anonymous

Guest
si.. said:
so are you running the pistons that came with the 2.2, what comp are they?
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just 87mm forgies from hks but it has a 2mm head gasket which might be a touch too much.
 
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Anonymous

Guest
Edd said:
Well we will see Sir oap-r, we know who's car has the most proven power so far :wink:

i hope your going to get it mapped for a bit more boost :twisted: :twisted: to suit your nice new clutch :wink: :twisted:
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as 1 of the mods keeps banging on about,yawn,torque is everything :twisted:

you`re thread hijacking again :twisted:
 
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Edd

Guest
oh yeh, torque is everything, aswel as being able to drive :wink:

anyway back on topic :roll:
 
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skiddusmarkus

Active Member
Two of 'em now Bruce :wink: .I've gone for 1mm HG so compression will be about 8.77:1.I'll be running Link ECU and water injection for high boost(hopefully 1.6-1.8bar) though.Should see me with loads of low down torque and a far whack across the revrange.If that's not enough then there's always the nitrous :D .And no,it isn't cheating :wink: .
 
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Anonymous

Guest
skiddusmarkus said:
Two of 'em now Bruce :wink: .I've gone for 1mm HG so compression will be about 8.77:1.I'll be running Link ECU and water injection for high boost(hopefully 1.6-1.8bar) though.Should see me with loads of low down torque and a far whack across the revrange.If that's not enough then there's always the nitrous :D .And no,it isn't cheating :wink: .
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i was thinking more of a 1.5-1.6mm head gasket and hopefully still keep 2.0bar on optimax with a seperate map for when using the race fuel.

nitrous is,and always will be for tight a%se cheats that can`t do it right :twisted: :twisted:
 
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skiddusmarkus

Active Member
was thinking more of a 1.5-1.6mm head gasket and hopefully still keep 2.0bar on optimax with a seperate map for when using the race fuel.
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As opposed to a seperate map for race fuel which isn't used on the road for normal driving either.Nitrous is a race fuel too IMO :wink: .
 
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Anonymous

Guest
skiddusmarkus said:
As opposed to a seperate map for race fuel which isn't used on the road for normal driving either.Nitrous is a race fuel too IMO :wink: .
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what happened to "back on topic" :wink:
anyway,my tank of race fuel will last longer than your 10sec...... :twisted:
could almost be talking about your sexual prowess there :twisted: :twisted: :lol: :lol: :lol:
 
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Sirnixalot

Guest
8.3:1-8.5:1 is an optimal safe range


a high compression motor running on the same fuel as a low compression motor will have to run less boost because of detonation. How ever the engine response, fuel economy and torque as well as having a finer tuned engine will far out weigh the socalled benefits of running 3bar of boost on cat piss that you get with a low compression motor.

You run race fuel on the same 2 setups except one motor is running an 8.0:1 CR and the other a 9.0:1 CR and the 9.0 will make more torque and hp than the 8.0:1.

The key with higher compression ratios is to keep the boost low on a day to day basis and only crank it when youve got racing fuel in the tank.

If anything keep the compression ratio standard and you will beable to run similar boost on the same fuel so long as the car is properly setup
 
Mr GTiR

Mr GTiR

New Member
yeah, i'm running 8.5:1 CR .......... some good advice given to me by a bloke with far too much time on his hands lol :wink:

btw, Nikko - i've sent an email to that company regarding CP pistons but no one has sent me a reply :( What should i do???
 
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skiddusmarkus

Active Member
Well I'm lucky enough to live near a place that sells race fuel.It's about £2/litre for 102RON(not as high an octane as some but not £5/litre either) I think and is worth considering for running high boost on a higher compression engine.I can see one major problem though.How do you make run the car just on race fuel without having 2 seperate tanks?There's always going to be some Optimax in the tank unless you syphon it all off.
 
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Anonymous

Guest
skiddusmarkus said:
How do you make run the car just on race fuel without having 2 seperate tanks?There's always going to be some Optimax in the tank unless you syphon it all off.
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most people,like i intend to,would just add the race fuel for special occasions like the pod,totb etc.i would try and use most of the tank on the way down and just add the race fuel at the venue.probably wouldn`t make any difference if you had a few litres (4-6) of optimax and 20-25litres of race fuel.you could then just top up with race fuel as the day goes on.you would also need to have a seperate map for the race fuel that you could d/load into the ecu or you wouldn`t get the benefit of it,except as a safety margin.
 
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