4age low compression but no turbo bolt on

[KIPH8N]

So my 4age blacktop motor is knocking and is smoking blue on my bzr after track day at puki.

So i will have to rebuild my engine. I was talking to jacobrjett about the rebuild he said that i can lower my compression with some 4agze pistons and maybe bolt on a turbo in future.

I have: turbo manifold
down pipe
link computer
intake plenum off silvertop
gt4 injectors
walbro fuel pump
link computer
redtop conrods
intercooler and piping
a spare blacktop block and crank
4agze gearbox with shaft and flywheel


all i need to get for rebuild is:
acl race series bearings.
arp rod bolts and head bolts
new oil pump
new headgaskit
4agze piston with rings
engine rebuild gaskit

So if i rebuild the engine with 4agze piston and drive my car and slap on the turbo after will it harm the engine? What do you guys think? And anything else i should include in my shopping list. I will be going to track days alot.

[Shrike]

Why do you have a silver top plenum??? one they wont hold boost and two they don't flow as well as a blacktop one (you can weld them up but I would suggest getting a custom one made ie from Barry)

What version link?

What gen gt4 injectors ? are they 440cc ?

T2 or t3 flange

550hp fuel pump?

It wont harm the engine as long as you run it in properly and tune it to suit

But it will be gutless compared to the factory blacktop :S

If you run the older 4agze pistons and a trd 0.8mm head gasket you will get roughly 8.5:1 comp or if you run the late model 4agze pistons (8.9:1) and a trd gasket youll get 9.5:1

What power goals are you after?

Ie a t28 from an s15 should be good for 180kwish atw at around 17psi and be fine running 9.5:1 comp assuming your charge temp and fueling is good

440cc injectors are good on a 4 cylinder to around 300hp at the engine

Can give more info once you answer

[tsoob]

yup, think about this what are you going to be using the car for, and what supporting mods will you do?

Brakes, Suspension etc are just as important as your power setup.

[.:O4AGTZ:.]

If you already have that list of parts, why not get the final bits needed and turbo straight away? Will be a bit of a pig to drive NA with the lower compression. Might as well do the whole job at once!

[KIPH8N]

Why do you have a silver top plenum??? one they wont hold boost and two they don't flow as well as a blacktop one (you can weld them up but I would suggest getting a custom one made ie from Barry)

What version link?

What gen gt4 injectors ? are they 440cc ?

T2 or t3 flange

550hp fuel pump?

It wont harm the engine as long as you run it in properly and tune it to suit

But it will be gutless compared to the factory blacktop :S

If you run the older 4agze pistons and a trd 0.8mm head gasket you will get roughly 8.5:1 comp or if you run the late model 4agze pistons (8.9:1) and a trd gasket youll get 9.5:1

What power goals are you after?

Ie a t28 from an s15 should be good for 180kwish atw at around 17psi and be fine running 9.5:1 comp assuming your charge temp and fueling is good

440cc injectors are good on a 4 cylinder to around 300hp at the engine

Can give more info once you answer

Well i had a silvertop before but then i upgraded to blacktop i know it wont fit so was thinking i would need a new plenum

Im after 300hp in the future.

The injectors are off the st185 gt4.

I have a 500hp fuel pump.

This is the link i have came with complete uncut loom. The old owner had it on his 4agte tuned on 15psi

http://s1128.beta.photobucket.com/user/ ... ort=3&o=74

[KIPH8N]

yup, think about this what are you going to be using the car for, and what supporting mods will you do?

Brakes, Suspension etc are just as important as your power setup.

Well right now i have coilovers on my car with twin pot brakes. What else would i need?

[Shrike]

Why do you have a silver top plenum??? one they wont hold boost and two they don't flow as well as a blacktop one (you can weld them up but I would suggest getting a custom one made ie from Barry)

What version link?

What gen gt4 injectors ? are they 440cc ?

T2 or t3 flange

550hp fuel pump?

It wont harm the engine as long as you run it in properly and tune it to suit

But it will be gutless compared to the factory blacktop :S

If you run the older 4agze pistons and a trd 0.8mm head gasket you will get roughly 8.5:1 comp or if you run the late model 4agze pistons (8.9:1) and a trd gasket youll get 9.5:1

What power goals are you after?

Ie a t28 from an s15 should be good for 180kwish atw at around 17psi and be fine running 9.5:1 comp assuming your charge temp and fueling is good

440cc injectors are good on a 4 cylinder to around 300hp at the engine

Can give more info once you answer

Well i had a silvertop before but then i upgraded to blacktop i know it wont fit so was thinking i would need a new plenum

Im after 300hp in the future.

The injectors are off the st185 gt4.

I have a 500hp fuel pump.

This is the link i have came with complete uncut loom. The old owner had it on his 4agte tuned on 15psi

http://s1128.beta.photobucket.com/user/ ... ort=3&o=74

300hp at the wheels or at the fly?

Im paranoid but I would include a surge tank in your list

You would need to retune the link to suit your build

Also its an older link so you wont get all the features of a newer model but it would work ok

st185 are 430cc 7mgte and 2jzgte are 440cc

st205 are 540cc

440cc should be ok at 180kw

[KIPH8N]

Why do you have a silver top plenum??? one they wont hold boost and two they don't flow as well as a blacktop one (you can weld them up but I would suggest getting a custom one made ie from Barry)

What version link?

What gen gt4 injectors ? are they 440cc ?

T2 or t3 flange

550hp fuel pump?

It wont harm the engine as long as you run it in properly and tune it to suit

But it will be gutless compared to the factory blacktop :S

If you run the older 4agze pistons and a trd 0.8mm head gasket you will get roughly 8.5:1 comp or if you run the late model 4agze pistons (8.9:1) and a trd gasket youll get 9.5:1

What power goals are you after?

Ie a t28 from an s15 should be good for 180kwish atw at around 17psi and be fine running 9.5:1 comp assuming your charge temp and fueling is good

440cc injectors are good on a 4 cylinder to around 300hp at the engine

Can give more info once you answer

Well i had a silvertop before but then i upgraded to blacktop i know it wont fit so was thinking i would need a new plenum

Im after 300hp in the future.

The injectors are off the st185 gt4.

I have a 500hp fuel pump.

This is the link i have came with complete uncut loom. The old owner had it on his 4agte tuned on 15psi

http://s1128.beta.photobucket.com/user/ ... ort=3&o=74

300hp at the wheels or at the fly?

Im paranoid but I would include a surge tank in your list

You would need to retune the link to suit your build

Also its an older link so you wont get all the features of a newer model but it would work ok

st185 are 430cc 7mgte and 2jzgte are 440cc

st205 are 540cc

440cc should be ok at 180kw

Okay man thanks i was just paranoid about the engine if it will run on low compression. 180kw will be just fine for now i guess. Thanks man

[jacobrjett]

Why do you have a silver top plenum??? one they wont hold boost and two they don't flow as well as a blacktop one (you can weld them up but I would suggest getting a custom one made ie from Barry)

It wont harm the engine as long as you run it in properly and tune it to suit

But it will be gutless compared to the factory blacktop :S

I believe he means a sealed plenum designed for the silvertop (IE silvertop itbs are 42mm, blacktop are 45mm) i saw a picture of it its all welded up and wont leak.

I suggested he run 4agze pistons so he could turbo in the future, I really wouldnt think it would make it "gutless" though, sure it would lose a bit of power but with a fresh rebuild with fresh rings etc. he would still have good compression anyway, i figured with the TRD head gasket and 4agze pistons it would still be a quick motor. I mean what would it be like 9/1 compression ratio? thats still more compression then most N/A engines right?

then considering the amount of turbo parts he already has, it wouldnt be long before he has a turbo conversion. Wont be gutless at all then

The only thing I was wondering was if the factory tune for the high compression ratio engine may not be very good on a low compression engine. thats what im wondering.

sure it would lose a BIT of power though but I doubt it would be as sluggish as you suggest... although im not questioning your knowledge about this stuff

edit: I am still amateur though, i am always willing to be corrected, im sure you guys know more then I do about this stuff.

[jacobrjett]

If you already have that list of parts, why not get the final bits needed and turbo straight away? Will be a bit of a pig to drive NA with the lower compression. Might as well do the whole job at once!

This man may be right. Youve already got most the parts, maybe you could just do it all at once.

[Shrike]

Why do you have a silver top plenum??? one they wont hold boost and two they don't flow as well as a blacktop one (you can weld them up but I would suggest getting a custom one made ie from Barry)

It wont harm the engine as long as you run it in properly and tune it to suit

But it will be gutless compared to the factory blacktop :S

I believe he means a sealed plenum designed for the silvertop (IE silvertop itbs are 42mm, blacktop are 45mm) i saw a picture of it its all welded up and wont leak.

I suggested he run 4agze pistons so he could turbo in the future, I really wouldnt think it would make it "gutless" though, sure it would lose a bit of power but with a fresh rebuild with fresh rings etc. he would still have good compression anyway, i figured with the TRD head gasket and 4agze pistons it would still be a quick motor. I mean what would it be like 9/1 compression ratio? thats still more compression then most N/A engines right?

then considering the amount of turbo parts he already has, it wouldnt be long before he has a turbo conversion. Wont be gutless at all then

The only thing I was wondering was if the factory tune for the high compression ratio engine may not be very good on a low compression engine. thats what im wondering.

sure it would lose a BIT of power though but I doubt it would be as sluggish as you suggest... although im not questioning your knowledge about this stuff

Stock ecu would over fuel causing bore wash I wouldn't drop the comp ratio without adding the link and tuning it also if you add 430cc injectors to it then it will over fuel alot more

Increasing comp is easier with a stock ecu as you can do things like increase fuel pressure (and factory blacktops run rich anyway) to make sure it doesn't detonate

compared to a factory blacktop at 11:1 comp 9.5:1 (late model 4agze pistons and trd gasket) comp would be a pig on the factory ecu (and not the best on a link) factory silvertop is 10.5:1 comp

If the sealed plenum is for a silvertop you could probably increase the port size to make it fit or remove the plate and weld on one to fit

Tuning isnt cheap your best to do everything at once

If you have a spare block build that up then when you have everything swap the whole engine in one hit means you just need one tune

even a fresh 8.5-9.5:1 motor wont compare to a 11:1 factory blacktop unless its got something wrong with it

Do it once do it right

[QikStarlie]

dropping the compression isn't going to make it run noticeably richer. nothing even close to bore wash level

dumping extra fuel after increasing compression isn't going to stop it detonating. amount of fuel doesn't have as much effect on detonation, as most people think, especially na. timing is what you will need to adjust.

dropping the compression to 9.5 isn't going to make it that lazy. sure it will loose a little bit , but will need to go alot lower than that to make a "pig"

agree its going backwards, but if its going to be turbo in a few months. why not?

[escortman]

Good basic list there.
Have you considered a td05 20g turbo, thats what i ran with good results
If doing track days would pay to look at a surge tank to be safe

[Shrike]

dropping the compression isn't going to make it run noticeably richer. nothing even close to bore wash level

dumping extra fuel after increasing compression isn't going to stop it detonating. amount of fuel doesn't have as much effect on detonation, as most people think, especially na. timing is what you will need to adjust.

dropping the compression to 9.5 isn't going to make it that lazy. sure it will loose a little bit , but will need to go alot lower than that to make a "pig"

agree its going backwards, but if its going to be turbo in a few months. why not?

I was trying to point out that adding compression to the blacktop with a factory ecu is easier then dropping it

Also was meaning borewash if there where 430cc injectors being used

and depending on the pistons it could be 8.5:1 comp

[escortman]

Shouldnt have borewash if its tuned properly

[Shrike]

Shouldnt have borewash if its tuned properly

yeah but then he would need two tunes :s

[escortman]

It wont run with the 440s or whatever he chooses to run with on factory ecu anyway.... I wouldnt bother changing any ecu fueling etc untill its turbo the slightly lower compression would be barely noticable

[jacobrjett]

yep that the way I looked at it, if it turned out to be able to run on factory tune with low compression pistons, do that until hes got all of the parts to turbo it. that way when he wants to turbo it he doesnt have to pull it to bits again.

And lets be honest, if you can drive a standard levin fast in the first place, its because you can effectively use small amounts of power, not because your engines fast, they are lacking in the power department so after scraping a bit of power off I doubt its going to make much of a difference. Unless your solely worried about drag racing or something. but who does that seriously with a mostly factory levin anyway, they are just good for little go karts.

I mean bazda succesfully drag races a levin by the look of it but his is FAR from factory.

[QikStarlie]

I was trying to point out that adding compression to the blacktop with a factory ecu is easier then dropping it

yeh and i was telling you it isn't. fuel required will not change enough either way, going higher or lower compression.

[KIPH8N]

Thanks for the information guys. The link ecu i have is off a 4agze map sensor ed tuned at 14psi. It came with uncut loom so will it be straight fit to my 20v