best cr for 1.6 bar td05

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David-Starlet

Member +
what would be the best cr to have if running td05 at 1.6 bar with some room for more boost at a later stage if i get bored. i have a set of brand new weisco 10cc dished pistons and a set of je flat top pistons that were used for only 1000km still perfect cant decide which to use and what size headgasket any advise?
 
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Skalabala

Member +
I would say it depends most on the management that is used and the tuner.
I would say go for the dish and get your CR around 8:1
Also make sure of what head gasket you are going to use.
Block must be skimmed and maybe have it O-ringed.
My tuner is running 2.5 bar on a standard 2JZGTE that has a CR of 8.5:1
 
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AdamB

Member +
I would use the 10cc dished pistons with a 1.2 or 1.4mm headgasket, depending on what the car is going to be used for.
You will be fine running around stock compression ratio 8.2:1 or a bit less if you want a bit more scope for the future. Do some calculations until you get the ratio that suits your setup.
As Azerty said, you will have to take into account the fuel you are going to use.
 
sx_turbo

sx_turbo

Lifer
10cc dish pistons with 1.2mm gasket will be close to 7.5:1, this is unnecesarily low, and will be a bit rubbish to drive off boost and be "laggy".

for 1.6bar boost, and with a good tune 8.5:1 will be fine, if you want to have a bit of leeway for future power increases, go for 8.2:1 this will enable you to run 2 bar boost on uk pump fuel,

there is also no need to have the block o ringed, if you use ARP head bolts these will be sufficient to keep the head clamped
 
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buckets

Member +
td05 it big enough on a 4e id go for a .6 trd gasket with wisco pistons if it was me better all round driving ,race fuel for bigger power keep well away from laggg,you can always dump a set of bigger cams in it later on to run more power as they lower comperssion to
 
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David-Starlet

Member +
e5 petrol is what ill be running maxol claim 99ron but id say its prob 97-98, will be mapped on a pfc and will be using 4age studs not sure what cams ill be using yet trying to find a set of 264's or something similar. was thinking around 8:1 would be alright this an everyday car at the moment so dont want a lag monster
 
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buckets

Member +
David-Starlet said:
e5 petrol is what ill be running maxol claim 99ron but id say its prob 97-98, will be mapped on a pfc and will be using 4age studs not sure what cams ill be using yet trying to find a set of 264's or something similar. was thinking around 8:1 would be alright this an everyday car at the moment so dont want a lag monster
Click to expand...

sounds good everyday car you dont want a laggy car id go .6 gasket as said td05s are big engough on 4es but push some good power out
 
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David-Starlet

Member +
with the .6 gasket cr would be roughly 8:1 i think? weisco say compression ratio with standard gasket is 7.8:1 afaik. am i right in thinking standard gasket is 1mm?
 
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jayc-glanza17

Fresh Recruit
stock hg is 1.2mm but as its composit its compressed to 1mm i think matey...
so 1.2mm hg is the stock size that stock cr is worked out on i think...
 
Chris@CCM

Chris@CCM

Member +
sx_turbo said:
10cc dish pistons with 1.2mm gasket will be close to 7.5:1, this is unnecesarily low, and will be a bit rubbish to drive off boost and be "laggy".

for 1.6bar boost, and with a good tune 8.5:1 will be fine, if you want to have a bit of leeway for future power increases, go for 8.2:1 this will enable you to run 2 bar boost on uk pump fuel,

there is also no need to have the block o ringed, if you use ARP head bolts these will be sufficient to keep the head clamped
Click to expand...

How can u be so sure u could run 2 bar on pump fuel ? And on what turbo ? I would be going lower for 2 bar
 
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David-Starlet

Member +
that doesnt seem right to me weisco say compression ratio with their 10cc dished pistons is 7.8:1 with a standard gasket so a .6 one would bump it up a bit
 
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AdamB

Member +
Never go by what anyone says until you measure the combustion chamber volume, the dish in the pistons yourself. Every engine is different, it may have had a skim previously, increasing the cr, without measuring and calculating yourself you won't know. Measure the pistons and combustion chamber, then you can fiddle with gasket sizes.
 
sx_turbo

sx_turbo

Lifer
my mates a series mini is running 2 bar on a stage 5 hybrid t2 type turbo on pump fuel with cr of 8.2:1, he is still using the carb, but has megajolt ignition

its all down to the build, qaulity of parts and the tune,

at the end of the day its all down to what the engine builder decides he is happy with, and if your doing the build yourself its down to what you feel comfortable with.

people with starlets are always far to scared to try new things, different things there is to much scare mongering, i will agree 2 bar is pushiong it at that cr, but there is no need to say it cant be done.

if i were to build another engine i would be going for a cr of 8.2:1 and running one of the new borg warner efr turbo's @2bar, with decent management.

anyhoo as stated its all down to the engine builder, and its best to do your own calculations
 
sx_turbo

sx_turbo

Lifer
David-Starlet said:
that doesnt seem right to me weisco say compression ratio with their 10cc dished pistons is 7.8:1 with a standard gasket so a .6 one would bump it up a bit
Click to expand...

yeah wossner say the cr with there 5/6cc dish on stock gasket should be 8.2:1 but infact gives much lower @7.8:1 when my engine was built
 
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Skalabala

Member +
sx_turbo buddy.. why do you go and bring the word "mini" up??
I just came from rehab for my "spend every penny I have on a mini" problem :(
going to upload a photo for you of my mini in the chill section :D

Bongskag bud, what bore did you use for the head gasket when calculating cr?
 
thefalls

thefalls

Member +
bongskag said:
I was looking into C/R for my new engine.. my calculations should be the same as yours pretty much with the -10cc pistons

Cylinder Diameter (mm) 74
Stroke Length (mm) 77.4
Number of cylinders 4
Chamber in cc's 40?
Piston dome in cc's -10
Gasket Thickness in mm 0.6mm (trd)

my C/R should be about 7.5:1 if i remember correctly, I used this calculator http://www.race-cars.net/calculators/compression_calculator.html
Click to expand...

Well using the cylinder diameter 74.5mm and chamber size 39cc makes the same compression ratio.

Note that the calculator doesnt use head gasket diameter,most of them are 75mm [ Aftermarket ones i mean.]

It does make a lazy engine offboost.

So what do we do with such an engine to make response better?

Port and polish the head
Some advocate a port only as polish doesnt help much.

And what else?
 
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