4age build

[mulkers]

G'day all.
I am looking to rebuild my lil bro's 16v ae86 with a bigport 4age.

I want to do some cams and light head work, with the intention of increasing top end torque, however am not particularly familiar with NA performance (plenty of vlts, skylines etc)

What parts/services can you suggest in accomplishing this?

Will start off with new long motor, full gasket set, head studs, head gasket, porting etc.

What cams do you suggest for increased top end torque, while still retaining factory computer, injectors, driveabiltiy etc.

what else needs to be done? valves? springs? seats/seals? guides?

Thankyou in advance, Michael

[oldeskewltoy]

Top end torque??? If you are looking to extend the torque range then you want to avoid a long duration camshaft. The longer duration camshafts build plenty of power(hp), but tend to sacrifice a wide power band to get those type of #s. Here is what I did when it came to big port porting....

Porting on a TVIS 4AGE is a ticklish job... it is VERY easy to royally #$@%$& things UP! The keys to porting a TVIS 4AGE is improving velocity! There are two key areas to do this.

The first is about 40mm behind the valves in the intake port. The 4AGE head was cast in two parts the casting comes together at this transition point where horizontal flow transitions to vertical flow. Each port is a bit over cast and a Dremel with a meduim drum works well here. ONLY blend the ports... DO NOT enlarge them... you just want the flaw do to casting to disappear, so remove ONLY the minimalist amount of material to make the port blend from above the flaw to below the flaw. BTW... you can't really see this flaw... but you can feel it with your finger tips!!!

The second area that needs attention are all the intake joints. It is bad enough that intake ports are so large that they do not flow well originally, but because of so many joints, these joints also add many eddy points. So each joint also needs to be blended. Now to do this there is a problem... there are no alignment pins, or dowels from the intake, to the TVIS plate. There ARE dowels between the TVIS plate and the head. So I added alignment pins(roll pins) to lock the intake to the TVIS. NOW the ports can be blended together... remember be a minimalist!

What cams do you suggest for increased top end torque, while still retaining factory computer, injectors, driveabiltiy etc.

Web makes a nice cam, they call their 294 grind, I've been using it for 8 years now, it pulls/makes power to about 7000 rpm("about" = give or take 100rpm). Stock cams usually run out of breath at 6600. Other cams that work well with stock fuel system parts would be HKS 256 or 264 cams. The 256 top out at about 7000, the 264 at about 7200. There are quite a few 272 type camshafts too, they top out at about 7500. Problem is 7500 is where the oem ECU has the redline and in some cases you might not make peak power before the ECU cut out.

Also stock injectors may mean you'll run lean. I'm running 20% larger injectors with my Web cams, you might want to look into a mild injector upgrade, just make sure you run the correct ohm injectors.

As for the rebuild.... check it all... but 4AGEs are pretty tough little engines I've seen disassembled 4AGEs with over 150k miles still showing cross hatching on the cylinder walls... with good valves and guides.

Valve springs will be needed if you run lifts in excess of 8.2mm(or there about) The Web cams have a lift of 8.18mm, I checked my springs for bind and although close... they DIDN'T bind with the 8.18mm Web 294 cams. There are some articles out there that say OEM spring bind occurs near 8mm.** OEM springs can be reused *IF* they are inspected using the FSM. New springs are usually between $120-$160 per set.

** -

The stock valve springs should not only be replaced, but also upgraded to ensure that the valves can follow the new and sometimes more radical cam lobe profile. The stock valve springs are only capable of ».318” (< 8.0mm) lift. With the stock installation height of 1.366” (34.7mm), they bind at 1.048” (26.6mm) compression and they will float some where above 8,000rpm.

http://www.club4ag.com/faq%20and%20t...haft_story.htm

[Lukey-KE20]

Start here:

http://www.billzilla.org/4agmods.htm

[feral4mr2]

smallport 10.5:1 c/r pistons are great in the bigport ge.

[mulkers]

Top end torque??? If you are looking to extend the torque range then you want to avoid a long duration camshaft. The longer duration camshafts build plenty of power(hp), but tend to sacrifice a wide power band to get those type of #s. Here is what I did when it came to big port porting....

Well, (Torque X RPM) / 5252 = Horsepower,

so high horsepower cams will give a larger torque figure at a given rpm.

So cams, lightweight, high-comp pistons, valve springs, as well as the parts i listed.

What are the limits of the factory injectors?

I suppose if the injectors are on their limit, new injectors are a comp will be a must.

I assume cam gears will also be required?

[oldeskewltoy]

Well, (Torque X RPM) / 5252 = Horsepower,

so high horsepower cams will give a larger torque figure at a given rpm.

So cams, lightweight, high-comp pistons, valve springs, as well as the parts i listed.

What are the limits of the factory injectors?

I suppose if the injectors are on their limit, new injectors are a comp will be a must.

I assume cam gears will also be required?

Well, running the stock ECU limits compression somewhat. I'm currently running the OEM high compression pistons(10.3 to 1) with my TVIS/AE86, and I'm careful to run mid grade or higher octane fuel. I do this because the AE86 does NOT have a knock sensor/ign retard.

Now there is a problem you'll encouter, the original 4AGE engines(most AE86s) use smaller* rod ends then the later engines do. This means the 4AGE in your bro's car uses 40mm rod journals and 18mm wrist pins. Later 4AGEs use 42mm rod journals with 20mm pins. That means to run high compression you either need a forged piston... OR you could rebush the later OEM high compression pistons to accept the 18mm pin. Some may say to shave the head to raise compression... you can do this... but by doing this you change cam timing.

Cam gears are a VERY good idea. HKS and Toda make springs. TRD still has some spring as well

[feral4mr2]

i use the smallport pistons (was sure they were 10.5:1 c/r....?) in my bigport aw11 engine, t-vis dis-connected. standard 9.4:1 c/r ecu, injectors etc. stock 10 degrees base timing. it pulls very hard, much more low to mid torque over the stock bigport 4age my bum dyno says.

[DeftAnesthetik]

i use the smallport pistons (was sure they were 10.5:1 c/r....?) in my bigport aw11 engine, t-vis dis-connected. standard 9.4:1 c/r ecu, injectors etc. stock 10 degrees base timing. it pulls very hard, much more low to mid torque over the stock bigport 4age my bum dyno says.

been wondering about 10.5s in a big port. glad to hear it can be done on stock ecu. does removing the tvis sacrifice bottom end in favor of more top end for you? if one wanted to keep some more power down low could it be left in?

[feral4mr2]

i left the t-vis plate in with the butterflies, drove it t-vis connected and t-vis dis-connected, felt the engine performed better with it dis-connected. the higher c/r makes up for the low down torque the t-vis helped with stock c/r IMO anyways.
the head was skimmed a bit before the rebuild too, so c/r could be a little higher again....

[mulkers]

I would likely be going to a forged piston anyway. I know that the 20mm rings are full floating circlips, how do the 18mm ones differ?

Are aftermarket pistons available in both sizes? or do you use all new pins and rings?
Does this depend on the manufacturer?

How does the smaller journal surface make a difference? (I realise less surface=higher potential speed)

The head will be lightly machined, but i do not want to go too far with this
(A friend recently pulled a shim out of his 1600's L20b, and had to back the timing of 16 degrees, to avoid pinging. It now has a broader torque range, but must have some crazy compression ratio!)

Will experiment with TVIS after the build is done.

Met a bloke in albury a few months ago, who's 86 had a gas solenoid on the TVIS to manually turn TVIS on and off. on a motor with no/little head work it had a positive effect, by delaying TVIS, it seemed to pull harder (for a few hundred rpm)

[wraith]

Performance Springs are Australian, and I've heard good things. Not badly priced, either. Apparently. Wade are Aussie too, and can point you in the right direction as far as cams go. They were very helpful when I contacted them.

If you are going to keep the stock ECU, I wouldn't get all exited with forged pistons. If you want new pistons, factory 20V ones will give good compression and as long as you change your timing belt at appropriate intervals you won't have dramas with valves vs pistons.

Good luck!

cheers

Ash

[DeftAnesthetik]

Performance Springs are Australian, and I've heard good things. Not badly priced, either. Apparently. Wade are Aussie too, and can point you in the right direction as far as cams go. They were very helpful when I contacted them.

If you are going to keep the stock ECU, I wouldn't get all exited with forged pistons. If you want new pistons, factory 20V ones will give good compression and as long as you change your timing belt at appropriate intervals you won't have dramas with valves vs pistons.

Good luck!

cheers

Ash

huh?..... is it just me or does his post really lack something?

[wraith]

HKS and Toda make springs. TRD still has some spring as well... Web makes a nice cam

Call me old fashioned, just trying to support local business.

I would likely be going to a forged piston anyway

Genuine Toyota stuff can be quite well priced, and will likely perform well in his application.

huh?..... is it just me or does his post really lack something?

So, while I may not have said 'do this and this and get a fully hektik dorifto racecar d00d111eleven1, I did attempt to contribute in a meaningful fashion toward the initial question. Thank you for your interest in keeping these forums full of potentially useful information.

cheers

Ash

[mulkers]

Call me old fashioned, just trying to support local business.


Genuine Toyota stuff can be quite well priced, and will likely perform well in his application.



So, while I may not have said 'do this and this and get a fully hektik dorifto racecar d00d111eleven1, I did attempt to contribute in a meaningful fashion toward the initial question. Thank you for your interest in keeping these forums full of potentially useful information.

cheers

Ash

Thanks. All opinions are welcome. I dont really have any brand allegiances, but i do have a budget, and i am just as happy to support local manufacturers/suppliers.

I will most likely change to an oversized piston, as i beleive the rings are to blame for the engine's tiredness (comps between 140-155 i think, done a while ago) so OEM pistons are an unlikely option.

A little O.T.; I know 16v pistons wont go in to a 20v, but does it work vice versa? For valve clearance etc.

Also, with a lightweight,forged, hi comp, piston, i would (at least i think i would) be doing it "right the first time"

[wraith]

A little O.T.; I know 16v pistons wont go in to a 20v, but does it work vice versa? For valve clearance etc.

Also, with a lightweight,forged, hi comp, piston, i would (at least i think i would) be doing it "right the first time"

I played around with this with a bigport head on a 20 valve block. I didn't get inteference at all (ie, piston at tdc, rotate cams 360 degrees), but it gets very close... with a thin gasket and shaved head- could be risky. Theres another thing- the 7A-FE head gasket is a stout thing. Genuine Toyota stuff will serve you well, particularly if your on a budget and keeping the stock computer! New piston rings are cheap...

cheers

Ash