Increasing Boost on 1g-gte

[Dr_boost]

Hi all,

i have a mkIII Supra 1g-gte late 1991 model wide body. Until now I was a silent viewer of the thread because I was alright with the cars performance and the gained alot from the expert knowledge of the members, but these readings have made me realise that maybe the engine has more potential. There have been alot of threads on the 1g-gte and they all had loads of information, except that there were tooo many opinions (not to mention the age old , put a 1j in) and I am not sure what to do.

the car has basic mods like the 3 inch apexi exhaust, with headers, apexi air management, lowered suspension and I am not sure of any other internal mods as It came from Japan. The boost its showing is 1st and 2nd gear -0.6 bar, 3rd and 4th gear it goes to 0.7 bar and at 5th i have noticed it going to 0.75 bar and sometimes coming back to 0.7 bar.

Here`s what I really need expert advice on or people who have had experiences with this engine. I want to increase the power a bit more without going over board on the expenses. I just thought increase the boost to 1 bar with the stock intercooler, but people tell me it can make the engine lean, or fuel cuts come in or i will waste the turbos. Any ideas suggestions on the boost or any other thing I can do ??

[88MKIII 1G-GTE]

What is this apexi air managenemt you talk off?

If motor is healthy gen 3 I don't see any issues with running 1 bar, just nothing over, and make sure you contoller doesn't spike.

I've always run 1 bar, stock turbos, stock motor, just exhaust, intercooler and a/c removed for better flow

[midnight_purple_GA70]

under any situation you need to check the AFRs when winding the boost up...

it wont lean due to the intercooler size it will lean due to not enough fuel being injected...

if this becomes a problem a simple fuel computer should help the problem providing the injectors and fuel pump are up to the task...

[Dr_boost]

@88mkIII - it is the part before the air filter, on the 1g-gte engines, sort of like a black box. I think thats what it is. It feels like a healthy motor, no blue/white smoke, runs rich, low mileage. I was thinking of investing in an electronic boost controller and set it at 1 bar, with everything else the same, not sure if it a wise choice or should I look out for some signs of problems ?

@midnight_purple - btw that is a nice color on the mkiii, I am looking for an increase keeping costs low and engine stock, for that I was thinking of just getting an electronic boost controller. It could lean out on boost increase, but would anyone know what is the safe limit, for the engine and turbos. Or would you still suggest purchasing an AFR meter ? I am guessing at this stage the injectors are stock, have not opened them up to see the color or cc.

know the options are endless but what would be the basic upgrade options to get some more power out of it, without having to change ecu, put bigger turbos, 1jz, bigger injectors, endless meters on the dashboard???

[88MKIII 1G-GTE]

It depends on where reliability and function comes into the equation. Running more boost is going to create more heat, more wear and tear, etc. Some things can be done very cheaply, but most should have supporting mods.

If your going to do the mods yourself there is heaps of easy things you can do to ensure it runs better whilst getting more performance. 1G-GTE run rich, so you can usually wind them up a bit and not have to worry but getting the AFR's checked is the only way to be sure.

For mods you can do without major work:
remove a/c
remove clutch fan and replace with AU thermo fans or other good flowing fans
lower thermostat (4A)
Larger intercooler
Dump pipes
Water injection
SAFC or similar interceptor
Electronic Boost Controller
Oil Cooler
Cold air induction

The most power you can really expect out of a Gen 3 1G-GTE on stock turbo's is around 180kws in my experience.

Most people I know end up doing bearings in their motors, so just make sure any leaky gaskets get replaced and dont over rev your engine.

[88MKIII 1G-GTE]

Btw the black you you speak off sounds to me like the air flow meter...

[kerzysgotasupra]

i read this with interest. no-one has mentioned shimming out the wastegates? easy done with washers, 6mm on each actuator equals about 1bar without the expense of boost controllers or other gadgets that may spike under boost and no chance of going lean. 1G's can take 1bar with ease.
also you can modify the air flow meter by taking off the top and increasing the tension in the spring by 3-4 teeth, this will notch up the fuel cut limit to around 18.5 PSI of boost.
also be aware that a standard 1G-GTE doesn't have a re-circ valve or b.o.v. so if you go to mad on the boost when you lift off the throttle and the intake butterfly closes the excess boost has nowhere to go except back towards the turbos, therefore trying to make the impellers spin the other way. this will make the shafts cavitate inside the housings and wreck the bearings inside.
i found a way to get 1.5bar out of my 1G-GTE but you really do have to know when to back off so as not to risk excess damage.

[Dr_boost]

What does shimming out the waste gates mean ? and how is it done by some one not very technical ? Also if I just do that, is it like one of those home made methods, which can back fire?

I like the tightening spring idea, but tell mehow would you measure 3-4 teeth ? and correct me wont this make it dangerous forthe turbos if they spike up ?

i was told by a man knoweldge on seeing the engine that it has a stock recirc blow valve and this is also why I can`t put just any b.o.v , coz the engine check might come or some other turbo issue, which made me believe it has a stock re circ blow off, but it is the quiet one. What do you suggest done?

@Kerzysgotasupra and 88mkiii

I am looking to keep my car at 1 bar, coz it is doing 10psi at the moment, i beleive that would be 20-30 hp gain. What would be the best course of action to get the car to 1 bar safely??

[88MKIII 1G-GTE]

i read this with interest. no-one has mentioned shimming out the wastegates? easy done with washers, 6mm on each actuator equals about 1bar without the expense of boost controllers or other gadgets that may spike under boost and no chance of going lean. 1G's can take 1bar with ease.
also you can modify the air flow meter by taking off the top and increasing the tension in the spring by 3-4 teeth, this will notch up the fuel cut limit to around 18.5 PSI of boost.
also be aware that a standard 1G-GTE doesn't have a re-circ valve or b.o.v. so if you go to mad on the boost when you lift off the throttle and the intake butterfly closes the excess boost has nowhere to go except back towards the turbos, therefore trying to make the impellers spin the other way. this will make the shafts cavitate inside the housings and wreck the bearings inside.
i found a way to get 1.5bar out of my 1G-GTE but you really do have to know when to back off so as not to risk excess damage.

I also have done said mod to afm, but haven't raised boost any more than 1 bar. I beleive the dump is to restrictive and would put to much pressure on the turbos to run more than 1 bar safely as a daily. With nice dumps, I would say 18psi would be fine as the gen 3 turbos are steel wheel (not sure about earlier gens), but you will run out of efficentcy very quickly. I would be using exhaust wrap, turbo beanies, A/F interceptor and water injection if I was planning on running the stock turbos at 18psi.

Saying all this, I know my car at one stage ran 25psi on stock turbos. Apparently it went really well, then after about 2 blocks started loosing boost as the turbo's were well out of efficency and werte producing too much heat. I would blame that for my oil leak. Funny the things you find out after you've bought a car...

[88MKIII 1G-GTE]

I would suggest electronic boost controller, expensive but the best. Allows turbo's to free spool until hitting 1 bar, instead of impeeding the flow as it gets towards the limit ie. more mid range.

I shall take a photo of the afm knob you can adjust and post it up a bit later

[Dr_boost]

Thanks.....Would the AFR meter be a wise investment or optional ?

[kerzysgotasupra]

believe me when i say that the standard 1G-GTE doesn't have a re-circ or b.o.v. of any kind.
if you have a pipe going from a point near to but before the throttle body back into your intake pipe after the AFM but before the point where the alloy pipes take the air to the turbos then this indicates a re-circ valve
mine definately did not have one.
the thread for modding the AFM is on here somewhere, but briefly entails removing the black square bit on top of the AFM using a sharp knife, mark the tooth that is engaged with the retainer, i used tippex for this, very slowly undo the phillips head screw that holds the retainer down MAKING SURE YOU DO NOT ALLOW THE TOOTHED GEAR TO UNWIND!!! increase the spring tension by rotating the gear by 3-4 teeth then lock the retainer back down. it is that easy.
to shim the wastegates out simply undo the bolts that hold the actuators to the turbo compressor housing and insert some washers so that you increase the distance between the 2 surfaces. this reduces the amount of travel that the wastegates can open and therefore increases top end boost. in my experience 6mm nets you around 1bar boost.
using exhaust wrap is a very good, worthwhile addition. yes its a bit of a ball ache to do but definately worthwhile.
also, i would definately install an air/fuel mixture gauge! i found it almost invaluable when modifying my car!
hope this helps

[Z2TT]

With a 1g-gte, add a medium sized inter cooler nothing huge with 2.5" Piping, Boost it upto 15 PSI.

Some people have mentioned that clicking the AFM 2/3 notches tighter gave a bit better acceleration, but the problem with that is it changes the fueling across the rev range. It's best to get something like an Apexi SAFC that can do it at specific points and get it tuned on a dyno.

Other than that a set of custom separated dump pipes will help and that's about all you can do with the stock turbo setup, also a 3" Exhaust might help a little bit.

After you have done all that and you don't like the way it drives, put a 1jz-gte or 2jz-gte in there.

[kerzysgotasupra]

With a 1g-gte, add a medium sized inter cooler nothing huge with 2.5" Piping, Boost it upto 15 PSI.

Some people have mentioned that clicking the AFM 2/3 notches tighter gave a bit better acceleration, but the problem with that is it changes the fueling across the rev range. It's best to get something like an Apexi SAFC that can do it at specific points and get it tuned on a dyno.

Other than that a set of custom separated dump pipes will help and that's about all you can do with the stock turbo setup, also a 3" Exhaust might help a little bit.

After you have done all that and you don't like the way it drives, put a 1jz-gte or 2jz-gte in there.

the point you're missing is, the chap is on a budget. he's trying to get the most from his car without having to spend much money.
here in the UK the apexi SAFC alone can cost around £200. then dyno time at around £80 an hour!?
the methods listed in previous posts are tried and tested and cost reletively next to nothing.

[Dr_boost]

@all

Thanks for the replies and support. Let me try and sum up what I understand I need to do from the above mentioned posts......please correct me or add to this if it helps more horses

@Z2TT

Intercooler is a great idea, except when I find one and get the piping and stuff, im afraid to calculate the costs :$ u dont think the stock intercooler is up to the task till 1 bar ?

As Kerzy suggested I need to get a BOV if I increase the boost. Could you tell me which make and model I should get, which is the time tested supra mkiii (twin turbo) BOV and i`ll just get that......some one also suggested a Bosch BOV as a economical option (need experts view).

I need to get a AFR gauge/meter to see if the fuelling is ok on increase boost....again any suggestion which to go for the 1ggte, as in make /model ?

I really liked the shimming wastegate thing but tell me, if i get the 20-30 quid manual boost controller would it be better ? if so again any suggestions.

The reason I am asking for the make and models are coz there are so many out there, and I am not on a titan supra budget to do a trial and error, so anyone got it on their 1g and its ook on 1 bar or above, i`ll go for it, or if there are any technicalities I should be aware of, shoot .....

Some of the most recent inputs iv got is a ecu piggyback which is around 150 (not sure) and requires no other above mentioned mods and increases power 25%........can anyone tell me if there`s any truth to this??