4agze pistons ina 7afe???, will they fit? Options

[StreetRacing10PS...]

I herd from a few ppl that 4agze pistons will fit in the 7afe, only thing is is that i thought the 4agze was a 1.6 and being that the 7afe is a 1.8 how would they fit?? Would the 4agze pistons be too small??

[nik]

I herd from a few ppl that 4agze pistons will fit in the 7afe, only thing is is that i thought the 4agze was a 1.6 and being that the 7afe is a 1.8 how would they fit?? Would the 4agze pistons be too small??
[right][snapback]275707[/snapback][/right]

the rods and block are shorter in the 4ag engines but stronger
both the 7afe and 4ag have 81 mm diameter pistons

[StreetRacing10PS...]

ok thanks, thats exactly what i needed to know. ill order them some time this week so when i get the turbo in and some new rods i can have it up to around 15 PSI

[nik]

ok thanks, thats exactly what i needed to know. ill order them some time this week so when i get the turbo in and some new rods i can have it up to around 15 PSI
[right][snapback]275719[/snapback][/right]

new rods and pistons and a 2mm head gasket you'll have to do the math on the displacment of the heads cc just the pistons will push from 8.5:1 to 11.0:1 (example go look at edo set up he did what you want to do) so use the gasket to lower your comp back down

also you might want to do a little work to the head if your going to 15psi nothing to bad maybe port it get a little more flow and maybe new valves

This post has been edited by nik: Apr 21, 2005 - 4:14 PM

[doGGy]

Ehm.... from 9.5 till 10.8 on stock bore to be exact.

ok thanks, thats exactly what i needed to know. ill order them some time this week so when i get the turbo in and some new rods i can have it up to around 15 PSI
[right][snapback]275719[/snapback][/right]

new rods and pistons and a 2mm head gasket you'll have to do the math on the displacment of the heads cc just the pistons will push from 8.5:1 to 11.0:1 (example go look at edo set up he did what you want to do) so use the gasket to lower your comp back down

also you might want to do a little work to the head if your going to 15psi nothing to bad maybe port it get a little more flow and maybe new valves
[right][snapback]275721[/snapback][/right]

[nik]

Ehm.... from 9.5 till 10.8 on stock bore to be exact.
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here is a link

http://www.6gc.net/index.php?action=members&itu=691


stock comp is 9.5:1 with stock pistons

4agze are made to make 8.5:1 or 8:1

but in the 7afe block with a 7afe head the comp goes up even with a low comp piston

in a few weeks i should know if a 4agze 8.0:1 piston in a 7afe block and 4agze head will go up or not i'm thinking it will a little probably a .5 to 1.0 increase if that happens i use a bigger head gasket to bring it to 8.5:1 or lower if possible

[Hanyo]

have we figured out how to connect the 4a pistions to the 7a rods?

I remember doggys saying something about it a while back

[Kwanza26]

have we figured out how to connect the 4a pistions to the 7a rods?

I remember doggys saying something about it a while back
[right][snapback]275819[/snapback][/right]

7A is press fit and 4AG pistons are full float. You'd have to machine the rod to full float pins instead of press...

[Hanyo]

so basically take the rod to a machine shop. and tell them to bore out the hole to hit the float pins.

[playr158]

ok we have rods covered

but where do we find the larger valves and retaining springs?

[nik]

ok we have rods covered

but where do we find the larger valves and retaining springs?
[right][snapback]276232[/snapback][/right]

the 7afe head or the 4ag heads?

[playr158]

7afe

[nik]

7afe
[right][snapback]276252[/snapback][/right]

with out doing any searching on my part get the valve diameter then length and see if any existing valve is the same if not custom time

up date
here http://www.bundy.com.au/Page1f.html
its under the nova 94-99 1.8l 7afe
there ss valves

remeber the geo, nova, corolla, and celica all got the 7afe motor

This post has been edited by nik: Apr 22, 2005 - 11:08 AM

[playr158]

just stick with new stock valves then

[nik]

just stick with new stock valves then
[right][snapback]276278[/snapback][/right]

in a 7afte set up i would leave them stock just cryo and shot peen them or polish its up to you but i would just leave them be

[playr158]

yea i really don't tend to change the size just have a 3 angle done

but shot peen is another good aspect

see i don't see why having the stock rods shot peen'd wouldn't fix the issue of them beeing week well
lets say this

i have my stock rods shot peen'd and i should be good for 200-225WHP?

[nik]

yea i really don't tend to change the size just have a 3 angle done

but shot peen is another good aspect

see i don't see why having the stock rods shot peen'd wouldn't fix the issue of them beeing week well
lets say this

i have my stock rods shot peen'd and i should be good for 200-225WHP?
[right][snapback]276316[/snapback][/right]

well i dont know. If you stick with stock rods i would shot peen them its a really good idea as for what kind of power they can handel i have no idea but at those levels i think you could be fine. Man i cant wait to get my 4340 Chromoly rods

[playr158]

well if you told me nik i would have gone in on rods with you
cause i want a set
ask then how much for a second set to be made

[StreetRacing10PS...]

Yea, I am looking at new rods too. I think I am going to have to go custom though

[Dr_Tweak]

Using 4AGZE pistons in a 7AFE will give you 11:1 compression. However, if you swap a 4AGE head on there, you'll be all set, 8.5:1 or 8.9:1 depending on which version you use. Plus the GE head is better anyway.

[playr158]

you pulled those numbers from where?

[nik]

Using 4AGZE pistons in a 7AFE will give you 11:1 compression. However, if you swap a 4AGE head on there, you'll be all set, 8.5:1 or 8.9:1 depending on which version you use. Plus the GE head is better anyway.
[right][snapback]276757[/snapback][/right]

do you have any info to back that up i know edo's comp rose but what proof do you have on the 4ag head ??

[playr158]

exactly ^^

[Dr_Tweak]

The difference in compression between the two engines is because of the head, so even using 4AGZE pistons ends up with high compression.

I haven't done this personally but I know several people that are running 7AGEs with 4AGZE pistons.

-Doc

[doGGy]

WRONG.

The diffetrence is not only in heads, the difference is in pistons - 7A pistons are DISHED, GZE almost flat, with the dished valve places. Pistons are the same height, but the difference is in these 10 cc that 7A piston Dish has.

The difference in compression between the two engines is because of the head, so even using 4AGZE pistons ends up with high compression.

I haven't done this personally but I know several people that are running 7AGEs with 4AGZE pistons.

-Doc
[right][snapback]277046[/snapback][/right]

[Dr_Tweak]

WRONG.

The diffetrence is not only in heads, the difference is in pistons - 7A pistons are DISHED, GZE almost flat, with the dished valve places. Pistons are the same height, but the difference is in these 10 cc that 7A piston Dish has.

[right][snapback]277244[/snapback][/right]

Think about what you're saying. If you swap the GZE pistons in, the compression goes up. Why is this not the case when you use the GE head? Because of the combustion chamber. Yes, the piston of the 7AFE is dished, which is part of it (I should have added that), but we're talking about using GZE pistons in a 7AFE.

When you use 4AGZE pistons in a 7AFE with a 7AFE head, the compression goes up.
When you use 4AGZE pistons in a 7AFE with a 4AGE head, the compression goes down.

Why? Because the head is different. End of story.

I wonder what the compresssion ratio would be in a 4AGE using 7AFE pistons?!

[doGGy]

here im talking about 7AFE with GZE pistons. Not the 7AGE. And CR with GZE pistons in 7AFE will be 10.8 if not using oversized pistons. With 82 Bore, and GZE pistons, the CR is at 11.02. This been proved on Edos car. As on stock 7A, you can count the CR, it will be 10.8 without overboring.

As for head swap, yes, the combusion chamber on GE head is bigger then on 7A, so the CR will drop noticibly.

WRONG.

The diffetrence is not only in heads, the difference is in pistons - 7A pistons are DISHED, GZE almost flat, with the dished valve places. Pistons are the same height, but the difference is in these 10 cc that 7A piston Dish has.

[right][snapback]277244[/snapback][/right]

Think about what you're saying. If you swap the GZE pistons in, the compression goes up. Why is this not the case when you use the GE head? Because of the combustion chamber. Yes, the piston of the 7AFE is dished, which is part of it (I should have added that), but we're talking about using GZE pistons in a 7AFE.

When you use 4AGZE pistons in a 7AFE with a 7AFE head, the compression goes up.
When you use 4AGZE pistons in a 7AFE with a 4AGE head, the compression goes down.

Why? Because the head is different. End of story.

I wonder what the compresssion ratio would be in a 4AGE using 7AFE pistons?!
[right][snapback]277274[/snapback][/right]

[Kwanza26]

Think about what you're saying. If you swap the GZE pistons in, the compression goes up. Why is this not the case when you use the GE head? Because of the combustion chamber. Yes, the piston of the 7AFE is dished, which is part of it (I should have added that), but we're talking about using GZE pistons in a 7AFE.

When you use 4AGZE pistons in a 7AFE with a 7AFE head, the compression goes up.
When you use 4AGZE pistons in a 7AFE with a 4AGE head, the compression goes down.

Why? Because the head is different. End of story.

It's equally the piston and the head. The older FE head designs had part of the combustion chamber carved into the piston top. Likewise, compression increase with the 4AGZ pistons is both because of the pistons and the stroke ratio. The 7A has a larger stroke ratio and that adds to the compression increase along with the flat topp-ed pistons. In a 7AGE, things will look more similar to the 4AGZE as far as compression goes, but it'll still be higher. I would estimate around 8:5 (7AGE) with the 8:0:1 4AGZE pistons and around 9:2 to 9:3 with the 8:9 pistons...

I wonder what the compresssion ratio would be in a 4AGE using 7AFE pistons?!
[right][snapback]277274[/snapback][/right]

Very low...

[playr158]

ok basically all we need to know is

4agze pistons at a 82mm bore
with a 7afe motor (no headswap)

[StreetRacing10PS...]

all i really wanna know is what do i have to do to lower my compression with forged 4age pistons in my 7aFE. is a thicker head gasket all i need?

[Kwanza26]

It'll raise your compression to higher than stock. Even with a thick headgasket, you're still looking at compression at stock levels... so it would really serve no purpose. One might think strength will increase... but that all comes down to tuning. 4AGZ pistons will be a bigger tuning hazard because relative compression increase will be mostly unknown, but expected in the high 10's... 4AGZE pistons is NOT a good way to go if you're looking to boost a 7AFE... Sure they're stronger pistons... but so what if tuning is gonna be that much harder...

[StreetRacing10PS...]

ok, so i get my turbo probly some time this week or when ever it gets mailed. and ill b runing around 8 PSI. but i wanna get the boost up to around 15+PSI but for that to b safe i would have to run forged internals, but if 4age pistons raise my compression to over 10:1 then it wont be safe on the engine. so is it worth getting the forged pistons or should i leave it stock??

[playr158]

you can boost a 10:1 cr fine at 10-15psi you just have to make sure that your emanager is tunned

but i'm goin to run
82mm bore with a 2mm headgasket
ported and polished head
shot peen'd rods
3 angle valve job
4agze pistons


imo don't use stock pistons if you wanna shoot for 10psi and over

[StreetRacing10PS...]

i no, i posted a pic in the off topic forum i think it was a few weeks ago of my friends eclipse that blew a piston runnin 13 PSI on his stock internals....not a pretty site..... too much boost

This post has been edited by StreetRacing10PSI: Apr 24, 2005 - 10:16 PM

[Kwanza26]

you can boost a 10:1 cr fine at 10-15psi you just have to make sure that your emanager is tunned

but i'm goin to run
82mm bore with a 2mm headgasket
ported and polished head
shot peen'd rods
3 angle valve job
4agze pistons


imo don't use stock pistons if you wanna shoot for 10psi and over
[right][snapback]277483[/snapback][/right]

why not use stock pistons? Your logic sometimes is just totally wrong. Even forged, because the compression is significantly higher, the heat will be significantly higher, putting just as much, if not more stress on the 4AGZ pistons as would a stock 7A with stock pistons... In the end... it's all about tuning.

You keep listing your little list of "soon to be" modifications... but I'm still not convinced you know what they actually do to the motor.

In the end, IMO, it's really not worth it to go through the trouble of installing 4AGZE pistons. If you must have pistons... get proper ones. Short cuts is what almost always kills custom turbo builds.

I'll still say though... if you're looking for 15 psi+... you can't look to do it cheap.

[Dr_Tweak]

The answer to your question is in this thread. But to lay it right out, it's like this:

If you want 15 psi, you have two options.

1. Do a 4AGE head swap and use the 4AGZE 8:1 pistons which will give you about 8.5:1 CR

2. Get custom forged low compression pistons. Have a look at http://www.importperformanceparts.net/ they have a complete 7AFE rebuild kit with ROSS/Wiseco forged pistons in any compression ratio you want for only $889... that's a sweet deal.

-Dr Tweak

*edit* Oh and I forgot: Never ever ever ever use a thicker head gasket to lower your compression. By doing that, you eliminate the quench (squish) area in the combustion chamber which will increase combustion temperatures and cause massive detonation and preignition problems. Worse than if you had left it at stock compression.

This post has been edited by raven_101: Apr 25, 2005 - 3:07 AM

[playr158]

well then thank you for the piston link
i knew goin to wit the thickerheadgasket always isn't a best way to do but hey its not like anyone has gotten the 7afte to the levels like these
and ha if i can get the custom compression pistons then i'm happier

[playr158]

oh and just so we get the line down
i refuse to swap heads or my motor
so give me the best info for a straight up 7afe
cause its goin to be an original motor project

[nik]

you can boost a 10:1 cr fine at 10-15psi you just have to make sure that your emanager is tunned

but i'm goin to run
82mm bore with a 2mm headgasket
ported and polished head
shot peen'd rods
3 angle valve job
4agze pistons


imo don't use stock pistons if you wanna shoot for 10psi and over
[right][snapback]277483[/snapback][/right]

i wouldnt use stock rods for 15psi even if they are shot peend

[nik]

oh and just so we get the line down
i refuse to swap heads or my motor
so give me the best info for a straight up 7afe
cause its goin to be an original motor project
[right][snapback]277657[/snapback][/right]

with the set up you are going with heat soak is a big factor because of the head design so the longer you run the less power

[playr158]

well then i better make sure i have an aluminum radiator with good coolant and good fans

[nik]

well then i better make sure i have an aluminum radiator with good coolant and good fans
[right][snapback]279583[/snapback][/right]

i'm still looking for a new rad i might do a honda race half radiator thats like 5 inch deep not sure yet

[playr158]

i'm not a big fan of half rads i'd rather run a skinnier full rad....

[nik]

i'm not a big fan of half rads i'd rather run a skinnier full rad....
[right][snapback]279591[/snapback][/right]

i would like a full length one but it might come down to room if i have the room i'll go full if i dont half will do it

[playr158]

i would say that the invader front we're both using is large enough to modify and runa full radiator mounted inside of it like infront of the heater core but behind the crash bar? maybe its possible
and makes more room

[94ST2]

OK I read through the post and we have seemed to have found a good custom piston to have stronger internals but what about forged rods where can we get those?

[playr158]

already been convered

you have two options

low boosting---stock rods shot peen'd
high boosting (10psi plus)
CUSTOM

[94ST2]

How much would the pistons and rods run?

[Kwanza26]

How much would the pistons and rods run?
[right][snapback]281186[/snapback][/right]

quite a bit... on average... around 600 bucks for custom pistons and 600 for rods...

[94ST2]

Yeah I was figuring around that much thanks.

[nik]

i would say that the invader front we're both using is large enough to modify and runa full radiator mounted inside of it like infront of the heater core but behind the crash bar? maybe its possible
and makes more room
[right][snapback]279684[/snapback][/right]

yeah i looked at that i just have to get some measurements and see what rad will fit plus i need the outlet and inlet on the passanger side or atleast the top one

[playr158]

i would say that the invader front we're both using is large enough to modify and runa full radiator mounted inside of it like infront of the heater core but behind the crash bar? maybe its possible
and makes more room
[right][snapback]279684[/snapback][/right]

yeah i looked at that i just have to get some measurements and see what rad will fit plus i need the outlet and inlet on the passanger side or atleast the top one
[right][snapback]281284[/snapback][/right]

oh you would have to use the 4age rad then huh?

well even if its not on the right side
you can go down to advancedauto or sumthing and pick up some extra hose thats just a bit longer and extend it.....that shouldn't effect anything...

[nik]

i just want it to look clean and not have 4' of hose in there

[playr158]

well you shouldnt see most of the hose since it will be inside the bumper

just the 1' that goes from the head/wp/block or what not
to the bumper enterance you keep the rest inside the bumper so you can't see it

[normality78]

bro's,

so may i assume that if i wanna build a high comp NA engine on 7aGE, which piston should i go for?

[playr158]

7age? your doing a head swap or a 7afe?

if your building a 7age then you HAVE to use 4age high compression pistons

if your using a 7afe....then normal 4age regular compression pistons will do just fine...you'll end up around 11:1cr

[normality78]

Tks dude.

Well engine has been open apart to check on condition now. most likely will go for a head swap. my mech was saying why not 20V but i don't really like the idea of having serious power comes only at 5500rpm later..

As for FE head, i felt its very "lazy" in revving

[playr158]

cause its an econobox head

[doGGy]

K, time to write it again.

As i know for now im the only one who TRYED TO PUT GZE pistons in the 7A.

First: EVERYTHING FITS LIKE IT SHOULD BE.

!!!!!!BUT!!!!!!

I used GZE (or GE)20mm wrist pin pistons. The wrist pin of the GZE is the same diameter as the 7A pins. BUT wrist pins of the GZE (or GE) pistons are FULL FLOATING, 7A pins are PRESS FITED. Difference is what 4AGZE rods have coper/bronze insert in the top of the rod, AND wrist pins float in it, and there is the oiling chanel in the rods for oiling the pins. 7A rods DO NOT have pin insert, DO not HAVE oiling cuz pin is pressure fitted and DOESNT move in the rod pistons move on the pin.

Then puting GZE (or GE) pistons MIND one thing: GZE pistons pins are full floating, so the restriction of the pin floting is in the piston. Then you press fit the GZE pins in the 7A rods - you get what the pistons dont have enouth of movment then they are cold (basicly pistons are stuck on the rods and kinda hard to move by hand if they are cold, but its enouth to heat them up a bit and they start to move...) This was the main reason what i aint used these pistons in my project (cuz i wanted to turbo my engine faster and aint had time to solve all this )

BUT, i asume using your STOCK 7A Pins with along GZE pistons - everything should and i say SHOULD be good... i dont know yet, i will try later about this...

Good luck guys.

[Dr_Tweak]

K, time to write it again.

As i know for now im the only one who TRYED TO PUT GZE pistons in the 7A.

First: EVERYTHING FITS LIKE IT SHOULD BE.

!!!!!!BUT!!!!!!

I used GZE (or GE)20mm wrist pin pistons. The wrist pin of the GZE is the same diameter as the 7A pins. BUT wrist pins of the GZE (or GE) pistons are FULL FLOATING, 7A pins are PRESS FITED. Difference is what 4AGZE rods have coper/bronze insert in the top of the rod, AND wrist pins float in it, and there is the oiling chanel in the rods for oiling the pins. 7A rods DO NOT have pin insert, DO not HAVE oiling cuz pin is pressure fitted and DOESNT move in the rod pistons move on the pin.

Then puting GZE (or GE) pistons MIND one thing: GZE pistons pins are full floating, so the restriction of the pin floting is in the piston. Then you press fit the GZE pins in the 7A rods - you get what the pistons dont have enouth of movment then they are cold (basicly pistons are stuck on the rods and kinda hard to move by hand if they are cold, but its enouth to heat them up a bit and they start to move...) This was the main reason what i aint used these pistons in my project (cuz i wanted to turbo my engine faster and aint had time to solve all this )

BUT, i asume using your STOCK 7A Pins with along GZE pistons - everything should and i say SHOULD be good... i dont know yet, i will try later about this...

Good luck guys.
[right][snapback]350743[/snapback][/right]

We already know this, what about the compression ratio? That's the question that hasn't been confirmed.

-Doc

[doGGy]

CR ratio was CONFIRMED like 10 times already, but it seems like no one read about it as well:

Using Arians 4AGE low comp pistons with 1 mm oversize in 7AFE Edo got 11.01 CR.

I counted what using 4AGZE stock bore pistons you could get at 10.8 CR

Using 2 mm headgasket from HKS and 4AGZE pistons (stock bore), (4AGE headgasket) the CR could be droped at 9.6

K, time to write it again.

As i know for now im the only one who TRYED TO PUT GZE pistons in the 7A.

First: EVERYTHING FITS LIKE IT SHOULD BE.

!!!!!!BUT!!!!!!

I used GZE (or GE)20mm wrist pin pistons. The wrist pin of the GZE is the same diameter as the 7A pins. BUT wrist pins of the GZE (or GE) pistons are FULL FLOATING, 7A pins are PRESS FITED. Difference is what 4AGZE rods have coper/bronze insert in the top of the rod, AND wrist pins float in it, and there is the oiling chanel in the rods for oiling the pins. 7A rods DO NOT have pin insert, DO not HAVE oiling cuz pin is pressure fitted and DOESNT move in the rod pistons move on the pin.

Then puting GZE (or GE) pistons MIND one thing: GZE pistons pins are full floating, so the restriction of the pin floting is in the piston. Then you press fit the GZE pins in the 7A rods - you get what the pistons dont have enouth of movment then they are cold (basicly pistons are stuck on the rods and kinda hard to move by hand if they are cold, but its enouth to heat them up a bit and they start to move...) This was the main reason what i aint used these pistons in my project (cuz i wanted to turbo my engine faster and aint had time to solve all this )

BUT, i asume using your STOCK 7A Pins with along GZE pistons - everything should and i say SHOULD be good... i dont know yet, i will try later about this...

Good luck guys.
[right][snapback]350743[/snapback][/right]

We already know this, what about the compression ratio? That's the question that hasn't been confirmed.

-Doc
[right][snapback]350884[/snapback][/right]

[nik]

I'M WITH DOGGY on this one it has been covered to death before

[Dr_Tweak]

Well sorry I asked, but every single time I tell people that you can't put GZE pistons in a 7A and have 8.5:1 compression they jump all over me, so I wanted to make sure I know what I'm talking about.

Such as these posts taken from THIS VERY THREAD:

Using 4AGZE pistons in a 7AFE will give you 11:1 compression. However, if you swap a 4AGE head on there, you'll be all set, 8.5:1 or 8.9:1 depending on which version you use. Plus the GE head is better anyway.
[right][snapback]276757[/snapback][/right]

you pulled those numbers from where?
[right][snapback]276789[/snapback][/right]

Using 4AGZE pistons in a 7AFE will give you 11:1 compression. However, if you swap a 4AGE head on there, you'll be all set, 8.5:1 or 8.9:1 depending on which version you use. Plus the GE head is better anyway.
[right][snapback]276757[/snapback][/right]

do you have any info to back that up i know edo's comp rose but what proof do you have on the 4ag head ??
[right][snapback]276953[/snapback][/right]

exactly ^^
[right][snapback]276955[/snapback][/right]

This post has been edited by Dr_Tweak: Nov 1, 2005 - 12:54 AM

[nik]

Well sorry I asked, but every single time I tell people that you can't put GZE pistons in a 7A and have 8.5:1 compression they jump all over me, so I wanted to make sure I know what I'm talking about.

Such as these posts taken from THIS VERY THREAD:

Using 4AGZE pistons in a 7AFE will give you 11:1 compression. However, if you swap a 4AGE head on there, you'll be all set, 8.5:1 or 8.9:1 depending on which version you use. Plus the GE head is better anyway.
[right][snapback]276757[/snapback][/right]

you pulled those numbers from where?
[right][snapback]276789[/snapback][/right]

Using 4AGZE pistons in a 7AFE will give you 11:1 compression. However, if you swap a 4AGE head on there, you'll be all set, 8.5:1 or 8.9:1 depending on which version you use. Plus the GE head is better anyway.
[right][snapback]276757[/snapback][/right]

do you have any info to back that up i know edo's comp rose but what proof do you have on the 4ag head ??
[right][snapback]276953[/snapback][/right]

exactly ^^
[right][snapback]276955[/snapback][/right]

[right][snapback]351274[/snapback][/right]

we just need to add the info to the stickies in this section