compression on 9:6:1

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ben10

Member +
does this sound right , my 4efe engine with all the other 4efte parts other than the block and head has 210psi compression on each cylinder... i no i am only running 0.6 bar of boost but damn it sounds well high, the 4efte pistons where reading 170psi across the board.

also it has been peaking just under 0.8 bar in the cold. and been a week of thrashing on and off and still solid. i am not running a lambda sensor either for the moment . but been keeping a eye on the afr and all seems to be well.
 
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AdamB

Member +
That is pretty high, as above what gasket are you using? Any history of the head being seriously skimmed?
 
5e colin

5e colin

Member +
the head must of bean scimmed several times already

i would not boost to high whit that compression if i was u

is your car not jerky now because of ur knock sensor pulling back is it connected ?
 
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elison

Member +
Thats high buddy for a boosted 4efte. The head must have had allot of trips to the machine shop. Keep an eye on the boost. Would not be adviceable to run to large boost
 
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ben10

Member +
hi guys then engine is not a 4efte..... its a jap 4efe engine with all my turbo boltons. misfiring turnt out to be the tps needed recalibrating and 0.6 is fine on boost the ignition has been retarded to 7 dbtdc and knock sensor is back on this block. fueling is not correct but could do with a piggy back just so i can tweak the fueling and ignition maps. iirc the lower compression 4efte pistons where around the 170 psi mark.

still stock 4efe block and head and headgasket has never been done .
 
Jay

Jay

Admin
Sounds about right, mine was 220 psi when I tested it:

julystuff009.jpg


Technically the same 4EFE, few years younger though.

Jay
 
Jay

Jay

Admin
ben10 said:
hi guys then engine is not a 4efte..... its a jap 4efe engine with all my turbo boltons. misfiring turnt out to be the tps needed recalibrating and 0.6 is fine on boost the ignition has been retarded to 7 dbtdc and knock sensor is back on this block. fueling is not correct but could do with a piggy back just so i can tweak the fueling and ignition maps. iirc the lower compression 4efte pistons where around the 170 psi mark.

still stock 4efe block and head and headgasket has never been done .
Click to expand...

4EFE with 4EFTE bolt ons no?

Apologies if I read it wrong.

Jay
 
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ben10

Member +
ime not lmao there 4efe pistons hence the 9:6:1 lol just all the other turbo bits lol

i am just wondering with that sort of comprssion could i go upto 0.8 bar of boost aslong as the timing and fuel is correct. tbh its been at 0.8 in the cold in 4th and 5th and it went like a stabbed rat.
 
Jay

Jay

Admin
Had mine running .8 on a CT9b for a bit but it's back down to .6 nowadays on a CT9a. Was also running .6 on a TD04 for a fortnight so there is a bit of lee-way with the fuelling.

Ideally you need it checked for det and AFR's properly to be absolutely sure it's happy. Ask a local tuner if you can get this done on the rollers then at least you will have a power figure to go on afterwards.

Jay
 
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ben10

Member +
Jay said:
Had mine running .8 on a CT9b for a bit but it's back down to .6 nowadays on a CT9a. Was also running .6 on a TD04 for a fortnight so there is a bit of lee-way with the fuelling.

Ideally you need it checked for det and AFR's properly to be absolutely sure it's happy. Ask a local tuner if you can get this done on the rollers then at least you will have a power figure to go on afterwards.

Jay
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hi mate. i am running a wideband and arf and its all running sweet 14.4 on idle and down to 11.2-11.5 under full load. and det i cant realy monitor but i have installed the knock sensor so when it detects knock it retards the timing anyway. manualy set the static timing to 7 degrees btdc. deff a big power increase between 0.6 and 0.8 tho. i do have the 4efte pistons to put in it if the stock 4efe give up the ghost and break the lands.

take it your on a 4efe block then jay?
 
Jay

Jay

Admin
Aye, I've been running a JDM 100ps 4EFE just like yours mate.

It's on stock timing and amazingly I've heard zero knock on any of those turbos I've thrown at it. Could just be lucky though, damn thing should have exploded in a satisfactory manner long ago I reckoned.

Your AFR's sound spot on although I would just get it rolling roaded and checked for det sooner rather than later. Better safe than sorry and all that.
 
5e colin

5e colin

Member +
dam i red it wrong sorry jay

ben ur comp is normal then whit the biggest dome of the gi pistons
when i fitted gi pistons in a 5efhe i got 220 psi + -
 
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ben10

Member +
5e colin said:
dam i red it wrong sorry jay

ben ur comp is normal then whit the biggest dome of the gi pistons
when i fitted gi pistons in a 5efhe i got 220 psi + -
Click to expand...

wicked man :) i prefurr higher compression and less boost. spool times are quick and has more power off boost.

what is the stock timing for a 100ps 4efe. i am at 10 d btdc now but may retard it to like 7 or so.
 
5e colin

5e colin

Member +
yep its 10 ben im suprised urs runs whitout knocking i had to pull timing back at 13 psi

is ur knock sensor tapped in the block / i think its not ?
 
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ben10

Member +
5e colin said:
yep its 10 ben im suprised urs runs whitout knocking i had to pull timing back at 13 psi

is ur knock sensor tapped in the block / i think its not ?
Click to expand...

when the engine was out i re drilled a hole in the rear of the block and tapped the thread. and removed the sensor from my other engine... i say i dont think mine is pinking, you can normally hear it..makes a horrible clicking sound. some ecu's even click inside the car to let you no its detting
 
weeJohn

weeJohn

Lifer
Yes it does. There is a torque setting for the knock sensor, 45 Nm rings a bell but I can't say for sure. Although the sensor is detecting a frequency, its a pressure sensor, reading the pressure waves in the block, looking for the knock frequency.
 
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