4agze build questions

[ae86boy]

Hi there,

I am writing you from Canada in the hopes of finding more information on 4agze buildups. I have searched the forums accordingly, but cannot seem to find clear answers to a few questions that I have about these motors in general...much less the specifics of my situations. I have come to you because most people up here do not do engine swaps, and if they do, tend to go for n/a power like 20v engines from ae101's. Most stay with simple bolt ons.

I have had a 1985 Toyota Corolla GTS (ae86...your "sprinter") for some 16 years now with which I have haunted the internet. In fact, some of you may remember me from years gone by and previous forums we have shared. Into this car I have swapped the 4agze motor from a 1989 MR2 aw11, which was at the time a 145hp (~108kw) motor, 8:1 compression twin cam 16 valve using approx. 6psi of supercharger boost off an sc12 blower. This motor is running off the OEM 1985 ae86 afm EFI system with no problems worth mentioning, including the oem ignition dizzy system. I have also wired the blower to turn on and off by switch, unlike the OEM system that does it by throttle control.

This 4agze has a ported, polished head with oversized 3sgte valves, 1985 ae86 "big port" cams, custom intake line, throttle body intake, supercharger outlet, "china core" intercooler and piping, intake, extractors, ABV mod, thin metal headgasket etc etc. I have been through several pulley sets in my quest for power, from ae86 4age oem (4psi), to mr2 4agze (6psi-8psi) to HKS (10 psi) to my current NST pulley producing 15psi and a measured 178whp (~133kw). It feeds this motor through a Mk III Supra fuel pump. The car has no emissions equipment (it isn't mandated here) to speak of nor any power options or wingdings...it is minimalist at best with the only engine accessory being the alternator and only vaccuum lines being brake master cylinder, fuel pressure regulator and boost gauge.

Having done this swap, I have had several problems arise that no one locally seems to have solutions to. I have searched the internet high and low and noted that once again, the only people who seem to have a clue are the Australians! I was hoping you folks could help out someone across the globe with a few simple questions that I have not been able to find an answer too using the forum search. I should point out at this time that I am mechanically inclined and I am not afraid of math...so please make this as technical or as simple as you feel you need to.

My first question concerns camshaft upgrades. I currently have the larger, "blue top" or "big port" n/a cams from the ae86 4age in the 4agze motor, which I believe are a 240deg, 7.5mm lift cam or somewhere near that and are quite a bit larger than the oem 4agze cams. Is there an advantage to going larger, to something like a 261deg intake/268deg exhaust 8.3mm lift cams? Information on this seems to be quite limited. I note that most people do not go wild on 4agze cams. I am limited here to the OEM computer though, which does cut the fun off at 7500rpm, so raising the maximum rpm isn't really an option. Do you folks have any suggestions/opinions on this subject?

Secondly, I find that my 4agze runs *quite* hot. Even with an upgraded 3 core aluminium radiator, Redline Water Wetter temperature control additive and no thermostat or other cooling blockoffs to speak of, the radiator can reach painfully hot temperatures in short order, with or without a cooling fan. Stop and go traffic is a no-no, especially on hot summer days where its hitting anything over about 25 degrees Celsius. Considering half of our summer is over this as a daytime high, I don't get to drive it a lot! Is this just a side effect of running as much boost as I am out of the sc12? I note the intake charge is still quite hot, even with the intercooler (I do not have exact numbers for temperatures). This problem arose once I went to the larger 15psi pulley...the car was significantly cooler on the HKS 10psi unit, though even then it was still quite a bit warmer than N/A. I should point out at this time that the motor runs quite rich as well, always under 13:1 air fuel...usually below 12:1. The only other mod I can think of that could affect this is I recently went to some General Motors supercharger oil rather than use the Toyota stuff.

Thirdly I seem to be having problems with headgaskets. This motor is on the third aftermarket metal 0.8mm three layer gasket this year. The first gasket blew between the cylinders and water jackets on #1 and #4 and was probably a result of a poor engine build by myself and a mechanic friend. This first gasket blew slowly, over time and was probably bad for years without actually being noticed. The second one blew out of nowhere, spraying out coolant from between the layers of the gasket into the engine bay, but no other effects were noted. I was parked at a stoplight and left the intersection at about 2/3 throttle (10psi/0.6 bar) and the engine just stalled. Once it finally restarted, the motor blew blue for a bit and I assumed the worst, towing it home. Once there, the spark plugs came out clean and new looking, as were the cylinder bores. Compression testing came back as 150/150/125/125 so I pulled the head to find nothing but the spot where the coolant had jetted out of the block. I have had the block and head surfaced and have recently gone to ARP head studs to try to "contain the beast", but I am sure this and the above symptoms are related in some way. Do you folks have any suggestions to help me keep this thing together long enough to chase some Ford GT's?

Lastly (for this moment, anyway) I wanted to thank you guys for the tidbits I did find using the search engine. The easy throttle body upgrades you've discussed previously were genius in design as well as the piping issues etc. that I've seen on this site. Thanks for the wealth of information! I'm going to put a bunch of it to the test asap!

Happy tuning,

mac

[trd16t]

hi mac

IN MY OPINION


firstly to go any larger with your cams you would need to upgrade computer to ems or other to even get the thing to idle otherwise the cam change would be pointless


SECONDLY AND MOST IMPORTANTLY


you NEED to run a thermostat not only so it opens at the right temp but slows the flow enough to actually cool when it passes through the radiator
I have a 4agte and have 221kw at the front wheels and have no heat problems
but did notice when i did not run a thermostat i had hunting for idle and to much heat at times

try a termostat first to try to solve this problem and you may find your head and gasket dramas may dissappear

i hope this helps


JOHN



p.s. WHAT WE WOULD LOVE IN AUSTRALIA IS THE PROBLEM OF THE HOTTEST DAY IN SUMMER OF 25 DEGREES WE ARE LUCKY TO GET THAT ON A COLD DAY IN WINTER.
ALSO WISHING OUR EMISSION LAWS WERE AS RELAXED AS YOURS.

[the_random_hero]

No thermostat is almost undoubtedly the cause of your cooling hassles Also a good idea to fit an aftermarket oil cooler, don't have to go crazy huge as bigger isn't necessarily better.
Fit an aftermarket ECU before you do anything else.

[fixeruperer]

if the motor is running hot, a thermostat isnt going to cool it down (not in this case anyway
). How have you done the cooling system, as in routing the hoses and thermostat housing.

Out of any of the blown head gaskets have you ever checked the block and head for straightness ? or just had them decked/shaved ?, if you have any warpage this will cause all of your over heating and blown gasket problems.

As said with the cams if you go too big you will need an aftermarket ecu, and the sc12 isnt a great blower when you have boosted it and trying to rev the hell out of it. You can try your 240 duration cams but with some adjustable cam gears (stick it on a dyno and adjust for gains) you could also try the sc14 blower that comes off the 1ggze 2lt cylinder motor with a little bit of modding it will fit.
The GM oil is fine and is not causing you any heat problems (over spun sc12 get very hot)
Factory Ecu's run pretty rich when you run more boost than factory, you can fix this by fitting a aftermarket ecu but then this opens more windows to bigger cams and blowers/turbos etc.
how far do you want to go with this thing ?


so are you using the N/A ecu on the blown motor? have you had the car on the dyno with a detonation mic ?

[ae86boy]

Thanks for the replies guys!

The cooling system is routed the same as OEM ae86...it runs out of the water pump at the bottom of the motor, into the bottom of the radiator using a long "j" tube from the back of the 4agze water pump. This goes into a 3 core, aluminium radiator that is an aftermarket upgrade made by a japanese company called Cooling Door West, and has all-OEM attacment points, fill points etc. The upper water neck off the head runs directly to the uppper radiator inlet. There is also a heater core involved, which runs coolant from the upper water neck along the block through the OEM aw11 4agze tube, to the heater switch, to the core, and then to the rear of the cylinder head...though I am unsure as to the actual coolant flow directions.

I am currently scouring junkyards in the area for an external thermostat housing that I can retrofit into the lower J pipe line line the OEM system had on the ae86.

Yes, I am using the n/a ecu on the blown motor. No dyno in my area has a detonation mic that I am aware of. It is not uncommon for us to hit 38-40c in the summer as highs, though you guys should be happy you don't get hit with the -45c lows that come with it.

I have had the head and block checked for flatness. The blow seems to be well within tolerance, while the head was out 4 thousanths of an inch. I had it surfaced and inspected. All is well at the moment and I have most of the engine re-assembled with an OEM headgasket. I hope it likes pressure because I could not find an aftermarket one in the country. Seems people up here are starting to forget about the Toyota 4a engines.

In doing all of this, I have swapped to an ae86 throttle body and increased the intake tubing size in the hopes of a few more kw. Do you folks have any other tidbits I should be aware of while I'm putting everything back together?

[oldeskewltoy]

Have you thought of using EVANS NPG+ coolant ? It should solve your overheating problem - http://www.evanscooling.com/index2.html.

For S/C applications and the stock ECU you want as much lift, with as little overlap. A long time ago HKS made a 248 cam...it was a decent upgrade. Most of the 256 cams can still be used in your application. I'd look for the 256 type cam with the highest lift.


You mentioned you had head work done... was the block deck ever checked? Has the head been re-checked for flat after each head gasket replacement? Using metal headgaskets usually requires perfect sealing surfaces.

[the_random_hero]

Grab an aftermarket ECU, first thing I would be doing. Your engine NEEDS a thermostat otherwise you cooling system loses most of it's efficiency (no impedance to flow through the block, so water doesn't get time to take all the heat away or lose the heat once it's hit the radiator).

[greywolf]

Oldskewl, any ideas where we can the Evans coolant in Australia ?

EDIT : Apologies for the thread hijack, I was googling and saw toymods had something about Evan's coolant, jumped in before reading the thread.

[ae86boy]

I have found a way to fabricate an inline thermostat housing, and I will be installing it shortly. I'll let you guys know what I find out once its all running again.

Thanks for the help guys!!!

I was thinking about high lift low(er) duration cams as well, though north americans seem to favour a TED components grind that has a lift in the 10.3mm range? It seems quite large.

[Chrisso]

That does seem large. I'd be wary of shim issues and spring binding with that much lift. To overcome the shim problems you could use bucketless shims from,I think a 1zz, it's in the interchangable parts thread.

[TERRA Operative]

Definitely need a thermostat. A TRD thermostat may be an idea? A water pump underdrive pulley (if not already fitted) will also help your overheating issue. The larger crank pulley will over spin your water pump, making the water flow through the engine faster, not allowing it to soak up the heat adequately.


Did you know you can also fit a 3SGTE throttle body without too much drama? It's 55mm instead of the stock 50mm, which equals a size increase of 17%. The www.JDMLevin.com link in my sig has the instructions on how to do it.

[ae86boy]

Seeing as you've done both the 4age and 3sgte throttle bodies, I have a question you can answer. Is the 3sgte body physically shorter than the 4age one?

I've just put the 4age tb off my old ae86 large port motor onto the 4agze and noticed that it sits high enough that the 90deg hose required to make the transition to the afm will interfere with the strut tower bar. It did this with the OEM tubing as well, though I just had a new flange-tube made that was less restrictive and shorter.

Thanks again for all the tech guys!

[TERRA Operative]

The 3SGTE TB doesn't have the pipe attachment like the 4AGE, it has the bolt on adapter, so you can make whatever you need to attach to it.

The 4AGE TB is 50mm tall, not including the pipe attachment flange thing (that's molded as part of the TB), add 25mm for that. I assume the 4AGZE TB is the same, I don't have one to measure...

The 3SGTE is 55mm tall, the stock bolt on adapter adds 35mm to the total height.

[ae86boy]

Okay...that didn't go according to plan.

I changed the throttle body with the one off the ae86 and now the car has a loping idle and stalls all the time...it won't maintain a constant speed. I have blocked off the coolant valve in the TB with vacuum caps, but it persists. I've tried adjusting and even removing the TPS to no avail. I also notice that the throttle body plate is sticking slightly at initial opening.

Anyone have any thoughts?

[TERRA Operative]

You need a throttle body that allows ECU control of idle speed.

4AGZE and gen2 3STGE I have confirmed to work. I used a 4AGE throttle body, but I had issues with unstable idle and stalling too, hence I changed to a 3SGTE throttle body.