Turbo Research Assistance

[IDon'tKnow]

Hey guys. It's dawned on me that I can boost the 4AGE for very little $$$ since I have a T25, intercooler piping, couplers, and an intercooler on hand.

I mentioned the idea and the response I got was research, research, research.

So I'd like to throw my thought process out there for review and criticism. Also, if you have a part/s that I need and are reading this, let me know what you're asking for it/them.

I'm an '86, completely bone stock.

I see a $190 (obo) manifold on eBay (Ta Da) and I'm wondering if it's worth the $$$$

The turbo is a T25 off of a 300ZX TT, almost brand new; had been replaced just before my buddy upgraded his turbos.

The intercooler is a side mount unit from an Audi S4; 11 row.... 7"x9"x2.75" core, 2" tubing.

I assume that a used SAFC for $100 will do the spark and fuel trick: Mount the AFM on the cold side of the compressor. Don't know if I should just swap to the GZE ecu - think the SAFC will be easier and safer.

Downpipe: should be simple with a scrap flange and my buddies welding skill -

Injectors: GZE injectors don't look particularly expensive new but maybe somebody could spare a set?

Hmm..... what am I missing?

[mr3]

Your 4age has fairly high compression. Boost + high comp = kaboom. You will be able to run more boost safely if you lower the compression with 4agze pistons. Use the rods as well they are stronger. You can boost the stock engine but very low boost. 3-5 lbs max I'd say. I never done it but I read a lot because I allmost did.

[IDon'tKnow]

I'm not really trying to blow the engine up but I had figured that could safely run at 8psi. I thought the compression ratio was 9.4:1 in the early 4AGE's?.......

I'm not really interested in pulling the motor to beef up the bottom end. If I'm going to go through the trouble of pulling the motor out I'm gonna put a 20V back in.

I've seen a few Honda B18C motors running 12-14psi on factory internals with no problems and those are 10:1 compression ratio.

Hmmm 3-5psi, something to consider I suppose. That just seems like too conservative of a number.

[donnyavery]

you can run 8- 10 psi safley with nothing more than 365 sc injectors ans safc on a sc ecu and flap (ive been doing it for year now (with a 75 shot wet nitrous and building a other with stock 9.4-1 compression)new 4agte budget build
and if you wont some pics of the last build donny's mk1 mr2 Photo Album - MySpace Photos

[IDon'tKnow]

What all is involved with swapping the ecu? Are the pin outs almost the same..... A few different sensors? How much do they go for around here?

[donnyavery]

Originally Posted by IDon'tKnow

What all is involved with swapping the ecu? Are the pin outs almost the same..... A few different sensors? How much do they go for around here?

its easiest to just get the hole harness and ecu and sensors then you just have to swap it all over no worrying about pin outs and computability its 1-2 hour job
price wise i dont know i took the long way around and made the hole harness if you can at lest find the ecu you can use the flap off of a late 87 or newer and that will take care of fuel cut (n/a ecu cuts fuel at 4 psi) but if you can get the ecu and all you'll have the knock sensor too and if you dont do the econo fuel switch the ecu will default to the prem timing curves but the hardest part is trying to track the parts down

[IDon'tKnow]

When you say flap I assume you're refering to the afm?
I don't think the knock sensor is absolubtely necessary, I know what detonation sounds like.
You're gonna have to fill me in on this fuel cut at 4 psi business. I didn't realize that the 4age used any engine load sensor apart from the afm. How does the computer know about the boost?
I'm also not following what you are saying about econo fuel switches and the ECU defaulting to prem curves.

[donnyavery]

Originally Posted by IDon'tKnow

When you say flap I assume you're refering to the afm?
I don't think the knock sensor is absolubtely necessary, I know what detonation sounds like.
You're gonna have to fill me in on this fuel cut at 4 psi business. I didn't realize that the 4age used any engine load sensor apart from the afm. How does the computer know about the boost?
I'm also not following what you are saying about econo fuel switches and the ECU defaulting to prem curves.

yes afm is what i mean by flap
with the motor where its at its hard to hear detonation and if you dont cach it in time you'll have a really big paper weight(aka blown 4ag)
fuel cut :the afm has a little (flap) in it in a na car the motor will only make vac to open it only so far. well with the turbo sucking in air it causes the flap (afm) to open to far this makes the ecu think there is a problem and it cuts fuel to save the motor you could try to use a voltage clamp to over come this but i think it will screw up the fuel maps any causing a new problem
the sc cars had a fuel selection switch high octane or to run low octane it changed the timing cerve for high octane had a more aggressive timing cerve for more hp because the high octane covers up the detonation
this is why i sed you can save a lot of aggravation by using the sc electronics

[IDon'tKnow]

Now the trick is finding them and at a good price.

[donnyavery]

Originally Posted by IDon'tKnow

Now the trick is finding them and at a good price.

yes i wish you luck

[IDon'tKnow]

I tHink the the advice I was given to just go megasquirt is good and sound.

[donnyavery]

Originally Posted by IDon'tKnow

I tHink the the advice I was given to just go megasquirt is good and sound.

yes and no the yes is that its very capable of tuning any thing you wont to but i don't now where you live but in pa its hard to find any one willing to tune it i even have a dyno shop two blocks from my house but they wont touch it but its a good and also cheap way to go you should find out if can find some with a base tune (or you'll spend weeks just getting to idle) and finding a capable tuner filmier with ms and 4age tuning

[IDon'tKnow]

I'm sure getting my hands on a base map will not be very difficult and a friend of mine owns a shop here in Huntsville by the name of TrackMasters. I haven't spoken with him about this but his website lists MegaSquirt as an ECU he tunes.

This whole project sounds like it's going to run me a few dollars more than the $350 I was hoping but I'm going to start taking steps toward it soon. I just can't live with a the acceleration I get with a stock 4AGE in a car that handles so well.

[espguitarist33]

ew pa...it sucks here donny! will you be streeting that turbo? u gotta find a non inspection station to dyno it

[scambo1]

Idontknow;
I am about to turbo a 4age also. I live in winchester, tn about an hour away. Please keep me posted on anything you find out. I was thinking the 4agze piston/rod route was the way to go to get to about 8.5:1 then boost the crap out of it -- 20 lbs plus. It will rev higher so rebuilding the head might be in the cards, but pulling the head can wait until after I tear it up because I dont know if that will even be the weak point. If you find a shop that will help tune it, let me know. If you don't lower the compression, I know for a fact you will blow the motor first time out.
scambo1

[yoshimitsuspeed]

Originally Posted by IDon'tKnow

I tHink the the advice I was given to just go megasquirt is good and sound.

The GZE ECU is really limited with serious low end leanout issues anywhere over stock GZE boost.
If you only plan on 8-10 psi it could be a decent choice. If you think you may ever want to run more than that you will be trying to work with a handicapped setup.

[toyotaspeed90]

There is quite a bit you are missing....

you will have to pull your pan in order to tap the oil return line. Is the T25 water cooled? you'll have to pipe that as well... using a turbo manifold you will probably have to remote mount your oil filter.

the problem with running a bigport on boost isn't necessarily it's compression, as the later gze's had 10psi and 8.9:1... but that the pistons are cast units and are not meant for boost.

That being said, I'm currently sourcing a bigport gze manifold to throw an n/a bigport into my gze car for fun until the smallport gze gets rebuilt..... that car, however, is already on MS.


If you go with MS the biggest problem you will have it 1) getting it started and 2) tuning it.

if you go with a gze ecu... it's tuned for 7psi and 8.0:1 compression... without easily being able to back out timing or increasing fuel... you're asking for the motor to end.


if you want to boost... then throw out the idea of swapping in a 20V, and get in the mindset that swapping motors is easy in these

[IDon'tKnow]

I don't think I will be taking it in the turbo direction right away, if at all. Over the next year or so I am just going to work on ironing out some of the major issues; driver rear accident damage, suspension, braking, ect.... and getting some systems ready for heavier modification - i.e. MegaSquirt (I'd like to try and get my hands on 3.0), fab exhaust and header, coil on plug ignition, tranny swap, short shift, ect...

I want to knock out all of the peripherals first because my long term goal is to have it running a built 20V with a Rotrex C30 and 288 or 304 duration cams. I'm not a wealthy guy so I'm just trying to focus on ensuring each new modification is in line with the ultimat goals. I don't want a drag only type car (obviously, it's an AW11) but I do want it to be break neck fast and handle like a shifter kart.

For now I have a Quaife rack and pinion on the way for modification #1. I'm working on buying a parts car from a guy near here as well so I will have the metal I need to repair the rear quarter and a few other little goodies.

[scottohno]

Originally Posted by mr3

Your 4age has fairly high compression. Boost + high comp = kaboom. You will be able to run more boost safely if you lower the compression with 4agze pistons. Use the rods as well they are stronger. You can boost the stock engine but very low boost. 3-5 lbs max I'd say. I never done it but I read a lot because I allmost did.

ok i have a turbo with an internal wastegate set to around 7 psi. i was wondering how i can get that to 4 psi about without getting a new turbo. could i just put a BOV inline with it? sorry, ima boost NOOB. i do have another turbo it wont fit on my exhaust manifold, theyre 2 different sizes and the big one has bad seas so id have to do that. i have a guy that can make piping for either one, but the one with the internal wastegate is a t25 and the one without thats bigger is i think a t45 off my friends mazda mx6 that blew up at 5lbs of boost. i dont want to blow up, i just want a bit more power and i want to get there with mostly the things i have. HELP???