Compression Test

[SNAP]

So i've just recently compression tested my 4a With good results all over the board.

My Question is on a Stock 4a 16v what Pressure reading would you expect in each cylinder?

In Both Runs i had results of 210 Psi in all 4 cylinders.

I don't exactly know what internals this motor has, weather its just head gasket or if its got Pistons 2.
its running a 0.8mm H/Gasket.. Head may have been decks as-well but i'm not sure of that either.

[Robo86]

thats pretty high, thinner headgasket and maybe higher comp pistons.

good comp for a stock 4a is like 170-180

[SNAP]

I'm to much of a need to.... need to know that is.. the results are to high for just a head gasket i would have thought
anyone else shed some light?

[Nikkojoe]

My bigport was 180psi across all cylinders when the bare engine was tested in front of me on a pallet hahaha.

But yeah, 170-180 is good

[af300e]

I tested a small port gze that was 195psi across all (dry).

[SNAP]

mayb 210 is about right with a 0.8 mm H/ Gasket... I'm not sure weather its small port or big port though, Any way to tell with the motor together?

[af300e]

Well the intake plenum might tell you the answer, although it is possible to adapt a bigport intake to a smallport head. The bigport intake is smooth on top and usually has a small rectangular ridge cast into it for the TVIS badge. The smallport has ribs running along it lengthways.

Someone may be able to add to this?

[AmyC]

My 4age after rebuilt head was 200psi on all 4

[SNAP]

<div class='quotetop'>QUOTE (af300e @ Jun 5 2008, 05:10 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=541894)</div>
Well the intake plenum might tell you the answer, although it is possible to adapt a bigport intake to a smallport head. The bigport intake is smooth on top and usually has a small rectangular ridge cast into it for the TVIS badge. The smallport has ribs running along it lengthways.

Someone may be able to add to this?[/b]


hehe getting their.. but its got Quads... ;)

[af300e]

hmm, not sure then. Someone will know how to tell without having to have the two side by side.

[slide86]

smallport should have the oil return on the back of the head.

also smallport has a knock sensor on the inlet side near the rear...(maybe just ZE engine?)

[Nikkojoe]

<div class='quotetop'>QUOTE (slide86 @ Jun 5 2008, 11:23 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=542139)</div>
smallport should have the oil return on the back of the head.

also smallport has a knock sensor on the inlet side near the rear...(maybe just ZE engine?)[/b]

All 7ribs have knock sensors, even the red/black top bigport 7ribs have them (provision on block)

[SNAP]

so i comp tested a mates Ae101 ssilver top 20 Valve last night and it got 200 psi in all 4 pots.... leme just search for the 20v comp ratio....

[Instigator]

Mine tested pretty close to 160 across all four.

Is this something I should be worried about?

[af300e]

<div class='quotetop'>QUOTE (Instigator @ Jun 12 2008, 03:04 AM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=544810)</div>
Mine tested pretty close to 160 across all four.

Is this something I should be worried about?[/b]

If it is NA it sounds pretty lazy. Even with seriously pissed off cams i wouldn't expect it to be that low. I tested a 2tg with 304/288 cams, est 10.5:1 (probably actually closer to 11:1) static CR and it was 220psi across all four.

Perhaps this is a good idea for a FAQ. Comp test results for all the 4AGE variants with stock cams/pistons and in good nick. Would give testers a benchmark to judge engine condition by.

[Instigator]

It's the motor in my ae71, NA bigport from an ae82 and as far as I know internally stock. She is blowing a bit of what I'm told is fuel smoke as well so maybe the motor is a bit tired?

I'm keeping an eye a small port on ebay at the moment so maybe worthwhile pulling mine for a rebuild to suit the turbo conversion I'm doing down the track...

[SNAP]

<div class='quotetop'>QUOTE (af300e @ Jun 12 2008, 07:21 AM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=544823)</div>
If it is NA it sounds pretty lazy. Even with seriously pissed off cams i wouldn't expect it to be that low. I tested a 2tg with 304/288 cams, est 10.5:1 (probably actually closer to 11:1) static CR and it was 220psi across all four.

Perhaps this is a good idea for a FAQ. Comp test results for all the 4AGE variants with stock cams/pistons and in good nick. Would give testers a benchmark to judge engine condition by.[/b]


Hey good suggestion, we should get this made into an FAQ,

Like i said mine 16v got 210psi but with - 0.8mm H gasket and 264 cams.. it really doesn't like to crank over- i just wish i knew the comp ratio it was running!!

[SpotterOne]

<div class='quotetop'>QUOTE (SNAP @ Jun 13 2008, 12:18 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=545535)</div>
Hey good suggestion, we should get this made into an FAQ,

Like i said mine 16v got 210psi but with - 0.8mm H gasket and 264 cams.. it really doesn't like to crank over- i just wish i knew the comp ratio it was running!![/b]

Mine cranks over just fine with exactly 11:1 compression, but I am running biggish cams with a heap of overlap. The motor is fresh as well, with new rings and bearings, and machined head and block.

Don't know what the compression test pressure is!

There is a way to work out if it is a smallport or bigport. You need to stick your finger between the #1 and #2 ports on the head. If you can get a finger in there, its a smallport. Here are a couple of comparison pics:

Smallport:
http://www.billzilla.org/4agsmallport.jpg

Bigport
http://www.billzilla.org/4agbigport.jpg

You wont know what the pistons are until you pull it apart.

[af300e]

<div class='quotetop'>QUOTE (SNAP @ Jun 13 2008, 12:18 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=545535)</div>
Hey good suggestion, we should get this made into an FAQ,

Like i said mine 16v got 210psi but with - 0.8mm H gasket and 264 cams.. it really doesn't like to crank over- i just wish i knew the comp ratio it was running!![/b]

If it is lazy to crank, maybe the timing is too far advanced. I would say that 210 sounds good for the specs you suggest. 264 cams are not all that aggressive. If you know what thte stock CR is, and what thickness a standard HG is, maybe you can guesstimate your current static CR.

[SNAP]

<div class='quotetop'>QUOTE (af300e @ Jun 13 2008, 05:14 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=545679)</div>
If it is lazy to crank, maybe the timing is too far advanced. I would say that 210 sounds good for the specs you suggest. 264 cams are not all that aggressive. If you know what thte stock CR is, and what thickness a standard HG is, maybe you can guesstimate your current static CR.[/b]

timing i checked was set to stock timing. 10' BTDC i think. it could prolly do with a little more mayb get a bit more top end out of it.
i font know what stock HG and comp ratio is, are all JDM motors bigport?

[mech`s blue]

it also depends on the guage you are using aswell.

usually you should not really on the actual figure it gives you but as a guide to determine each cylinder in relation to other cylinders. i.e picking out lazy/low cylinders

i have used different guages from old to new and different brands and they will all read differently. 210 on one guage could be 180 on another etc. i have even had 2 of the same brand guages on the same engine read differently

[skit]

<div class='quotetop'>QUOTE (Mech`s Blue @ Jun 15 2008, 02:01 AM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=546170)</div>
it also depends on the guage you are using aswell.

usually you should not really on the actual figure it gives you but as a guide to determine each cylinder in relation to other cylinders. i.e picking out lazy/low cylinders

i have used different guages from old to new and different brands and they will all read differently. 210 on one guage could be 180 on another etc. i have even had 2 of the same brand guages on the same engine read differently[/b]


Fair call.

My stock bigport (220k km, never rebuilt) gave 145-150psi across all four under a dry comp test, with my cheapo supercheap gauge. It still packs a reasonable punch, but blows a little smoke under load, so rebuild time is coming. Dyno'd at 99hp@wheels with quads & aftermarket ecu.

I recall the manual stating 135-140psi is rebuild time.

[ae86trueno]

It sounds about right to me,

my stock 100KW bottom end, with new pistons, and rings, 0.5 TRD Head Gasket, 270 ish cams, and quads,
comes in at 260 PSI across all four on the last cold test i did.

but we are putting out 95KW atw now.

Ben.