2.8/3.4 turbo selection. please help

[TTT123]

sounds pretty straight forward and from what I'm reading everywhere else... definitely worth it the work for tuning ability. thank you for the input, i will be reading up on it tomorrow at work... i love going to work so i can research car stuff lol

anymore thought on head work for this motor guys. i'm quite good at porting and polishing so i just assumed i would do the works on these heads but that thread that mentioned i would loose 10 to 15 hp if i gasket matched these heads made me scratch my head ..... less restriction... more air...better performance..not so with the 3.4 heads???

thanks

[caffeine]

There is also velocity to consider. Larger ports could mean slower airflow. As long as they're not too small.

[Guest]

anymore thought on head work for this motor guys. i'm quite good at porting and polishing so i just assumed i would do the works on these heads but that thread that mentioned i would loose 10 to 15 hp if i gasket matched these heads made me scratch my head ..... less restriction... more air...better performance..not so with the 3.4 heads???

thanks

I remember reading stories of people swapping to 7730 computers for their iron head 3.4 swaps and picked up no power. In fact I remember someone dynoing it and it showed no hp gain even with lots of supposed tuning on it by the owner. A 7730 was never designed for a iron head turbo setup, so switching to a 2 bar map is going to lose resolution no matter 7730 or stock fiero computer.

OP you also mentioned wiring isn't your strong suit, so swapping computers and wiring might complicate things for you more than need be. Especially since it doesn't have to be done in order to effectively add a turbo.
.
85 GT fiero computer was setup for boost if you can find one of those and can be programmed for a knock sensor too.

port the heads, you won't lose power. What link or thread did you read where they said you would lose power? Was it on pennocks? Don't listen to those people.

Once again, how much power do you want to make and what is your budget?

[caffeine]

I remember reading stories of people swapping to 7730 computers for their iron head 3.4 swaps and picked up no power. In fact I remember someone dynoing it and it showed no hp gain even with lots of supposed tuning on it by the owner. A 7730 was never designed for a iron head turbo setup, so switching to a 2 bar map is going to lose resolution no matter 7730 or stock fiero computer.

OP you also mentioned wiring isn't your strong suit, so swapping computers and wiring might complicate things for you more than need be. Especially since it doesn't have to be done in order to effectively add a turbo.
.
85 GT fiero computer was setup for boost if you can find one of those and can be programmed for a knock sensor too.

port the heads, you won't lose power. What link or thread did you read where they said you would lose power? Was it on pennocks? Don't listen to those people.

Once again, how much power do you want to make and what is your budget?

I wouldn't expect any horsepower gains from a 7730. If a Fiero ECM is tuned properly it should be capable of making the same power. That being said, however, I would never want to tune with a Fiero ECM. The reasons are listed below.

You CAN tune for boost without losing resolution with a 7730. I just explained above how you can run codes that are DESIGNED for boost on a 7730 or 7165. When you tune with $59, $59, nAst1, $8F, or $12p, you're using code that was meant for boost and doesn't sacrifice table resolution to read > 100 kPa. In the case of nAst1 and $12p, you actually GAIN VE resolution because they have been modified for new VE and spark tables, among other things.

The 85 Fiero ECM was never setup for boost but some have made it work by using a 2-bar and doubling the VE values. That's why I call it a hack job. They're not actually modifying the code properly for boost. I am also aware that the 85 ECM can support a knock sensor.

There's yet another MAJOR gain with an ECM swap. The Fiero ECMs are almost useless for datalogging with because they only update every 1.5sec or so. Compare that to the 7730 and 7165 which update at multiple times per second. The extra datalogging info makes it that much easier to tune a new setup. And then to top it all off, the newer ECMs are simply faster at processing. Faster processing = smoother running engine.

[caffeine]

3400/3500 heads are a bit touchy when it comes to porting apparently. Hard to know what to touch without a flow bench. 3.4 iron heads OTOH are apparently easy to port.

[TTT123]

I remember reading stories of people swapping to 7730 computers for their iron head 3.4 swaps and picked up no power. In fact I remember someone dynoing it and it showed no hp gain even with lots of supposed tuning on it by the owner. A 7730 was never designed for a iron head turbo setup, so switching to a 2 bar map is going to lose resolution no matter 7730 or stock fiero computer.

OP you also mentioned wiring isn't your strong suit, so swapping computers and wiring might complicate things for you more than need be. Especially since it doesn't have to be done in order to effectively add a turbo.
.
85 GT fiero computer was setup for boost if you can find one of those and can be programmed for a knock sensor too.

port the heads, you won't lose power. What link or thread did you read where they said you would lose power? Was it on pennocks? Don't listen to those people.

Once again, how much power do you want to make and what is your budget?

my fiero is an 85gt. is there a way to tell if the ecm is different then others.

my budget isnt really to an amount per say. in my head i was thinking about putting maybe $1000 into this build. i can do 90% of the work myself and i already have turbo parts laying around from other builds. i think the only thing I'm going to end up buying other then maintenance stuff for updating old stuff is a new cam, rockers, timing chain and have the heads get a valve job. then i will do all assembly and porting type stuff. fabbing up my turbo wont be a big deal... i have all the tools for welding up headers, turbo plumbing, etc.

[TTT123]

guys this is all great info.... thank you so much for sharing and giving me things to research and consider.

[Guest]

Codes I'm talking about are the overall program that runs the engine. Certain codes can run on certain ECMs. Some are modified programs based on other codes (like $12P, $59, nAst1), while others are factory.

The common code used to run a 3x00 is $A1, which is the factory J-body 3.1 code. TPI V8s usually use $8D IIRC.

The ones that support boost natively (not requiring a 'hack' job) that I know of are $58 (Sy/Ty, 2-bar), $59 (modified Sy/Ty 3-bar), $8F (Turbo Grand Prix, 2-bar), nAst1 (modified $A1, 1, 2, or 3-bar) and $12P (I think this one is based on a Holden code, 1, 2, or 3-bar).

$58, $59, $8F and nAst1 all will run on 7747, 7730, 7727, and 9396 ECMs, code $12p needs a 7165 or equivalent.

I think you mean '7749, not '7747.

The '7749 is in the same "family" if you will, as the '7730 and '7727. The differences here are that, the '7749 has two injector drivers, and is missing a quad driver. The '7730 has a single injector driver, and an extra quad driver. The '7727 is an underhood version of the '7730 and uses different connectors than both the '7749 and the '7730.

The choice between the '7749 and the '7730 basically comes down to the injectors you will use. If you are using high-Z injectors, either ECM will work, but if you are using low-Z injectors, the '7749 is recommended, though it may need a change in the injector sense resistors and the injector drivers. There is information on this, but if low-Z injectors are not a concern, then it's not worth discussing.

I remember reading stories of people swapping to 7730 computers for their iron head 3.4 swaps and picked up no power. In fact I remember someone dynoing it and it showed no hp gain even with lots of supposed tuning on it by the owner. A 7730 was never designed for a iron head turbo setup, so switching to a 2 bar map is going to lose resolution no matter 7730 or stock fiero computer.

OP you also mentioned wiring isn't your strong suit, so swapping computers and wiring might complicate things for you more than need be. Especially since it doesn't have to be done in order to effectively add a turbo.
.
85 GT fiero computer was setup for boost if you can find one of those and can be programmed for a knock sensor too.

port the heads, you won't lose power. What link or thread did you read where they said you would lose power? Was it on pennocks? Don't listen to those people.

Once again, how much power do you want to make and what is your budget?

The 1227749 and 1227730 were never designed to run a Nissan I6 turbo either, but they do, and quite well. The 16147060 was not designed to run a '70s Olds 455 that has had some extensive internal work done it, along with a custom 4 bbl throttle body and 4L80E, but it does that quite well in my friend's '72 Cutlass. The 1227730 was never designed to run a 409 with a custom MPFI intake, but it does that well, I could keep going about how certain ECMs were never designed to run certain engines or combinations but I think you get the point.

How can using code that is designed to work with greater than 1 BAR map sensors going to "lose resolution"? Even using stock codes ($58, $8F) you will not lose any resolution over the tune-able range in the fueling. They are set up with a typical 1 BAR table and then use a multiplier table for fueling control above 100 kPa. The modified codes ($59, $12P) use tables that are far more developed, with many more points to find tune the fuel delivery. $58, $59 and $8F will all run in the '7749, 7730 and '7727. As mentioned $12P runs in the '7165 and '808. I have used both $59 and $12P and both are great. I have MUCH more time with $59, but $12P could be the replacement for me, for various reasons.

Are you looking at peak power only, or the area under the curve, when you claim that no additional horsepower was made with an ECM swap and tune? I would not be surprised at all if peak power stays the same, but would be very surprised if the area under the curve did not change, with good tuning.

The '85 Fiero ECM was the 1227170 AFAIK, it uses $24 and is NOT set-up for 2 BAR MAP sensor, therefore NOT set-up to run a turbo, without getting into fudging numbers. You can download all of the 1227170 files here: http://www.gearhead-efi.com/Fuel-Inj...Information-24 Have a look for yourself. The VE and SA tables only go to 100 kPa.

[34blazer]

The '85 Fiero ECM was the 1227170 AFAIK, it uses $24 and is NOT set-up for 2 BAR MAP sensor, therefore NOT set-up to run a turbo, without getting into fudging numbers. You can download all of the 1227170 files here: http://www.gearhead-efi.com/Fuel-Inj...Information-24 Have a look for yourself. The VE and SA tables only go to 100 kPa.

iirc $24a is used for boosted apps. Some of the fiero crowd would need to chime in to describe it, I never looked into it because its simple crap to swap in a 7730.

Big cheese, a 7730 has been swapped to run a SBF with great success.

[TTT123]

I'm taking notes guys lol

[Guest]

iirc $24a is used for boosted apps. Some of the fiero crowd would need to chime in to describe it, I never looked into it because its simple crap to swap in a 7730.

In what application? I can only find $24 and it only supports 1 BAR.

[caffeine]

If it came factory with a 1-bar, it's not meant for tuning boost.

[ericjon262]

I'm taking notes guys lol

might check some of this out:

http://60degreev6.com/forum/showthread.php/48100-nAst1-Progress-and-Concepts-Thread

there's also

http://www.gearhead-efi.com/Fuel-Injection/forum.php

Lots of cool info on programming and tuning in there. if you're a programmer by trade you'll make alot more sense of most of it then I will.

[TTT123]

might check some of this out:

http://60degreev6.com/forum/showthread.php/48100-nAst1-Progress-and-Concepts-Thread

there's also

http://www.gearhead-efi.com/Fuel-Injection/forum.php

Lots of cool info on programming and tuning in there. if you're a programmer by trade you'll make alot more sense of most of it then I will.

thanks

[ericjon262]

don't believe everything you read over there.

to further substantiate my comment:

Originally posted by AL87:

port everything! throttle body, upper and lower intake plenums, intake manifold, heads, exhaust headers, y-pipe!
if you turbo, you'll need some custom piping on the exhaust side anyways.

crate 3.4s use a comp 260H equivalent, so at least use that! 272H is recommended because of more overlap, it makes for better high rpm power/torque.
but if you turbo, you may want to stick with a 260H its for mild turbo applications as well.

if you don't turbo the engine, stock pistons are fine, if you are in the middle, you may want to go with at least a hypereutectic. if for sure, go forged.
unless you want to keep the boost at or under 10psi. (common rule for every 10lbs of boost, is +%100 more power)
(3.4 stock is about 170 at the crank, so add 10psi boost and you have 340 at the crank effectively)(before you add a cam)

use an MLS gasket system (100 bucks a gasket) or do the old school thing and get grooves cut for a "special" sealing ring to be used with standard gaskets.

not sure if 3.4 injectors can facilitate the use of a turbo. it could all depend on the boost you want to push.
As for a computer upgrade it, you definitely want a custom tune, if the injectors can deal with a turbo's demands, you'll want to be able to tune them to stay open a little longer. and you'll be able to play with the rates of when the cooling fan turns on and off, and where you want your normal operating temperature to be around.

ALSO, I'm not sure if a turbo can fit in the engine compartment of a M/T Fiero, because the turbo would normally sit around where the shifter cables will be going, may want to consider this, some cut out the trunk, but those guys are crazy mo-fo Fiero speed demons, who push their engines to the limits...

half or more of what is in this post is complete bullshit.

http://www.fiero.nl/forum/Forum2/HTML/131516.html