Considering 3400 swap (not DOHC) into my 88GT 5-speed, need advice (Page 1/2)
phils88GT FEB 17, 10:09 AM
So after pondering what swap I want to do in my 88GT 5-speed. I think I have settled on the 3400 non-DOHC swap. I am not looking for massive amount of power, but an increase of any kind would be nice. Whatever motor I end up getting, I think I am going to drop the preparation a bit in preps for maybe a low boost turbo setup after a rebuild. What would be the best way to accomplish that? Is there much of an aftermarket for these engines? Would like to find a rod / piston combination to make for a more boost friendly compression ratio.

Second, I need a clutch. I actually need one now as whoever installed the clutch I have did something wrong because it slips like pad when you try to accelerate very hard. Not sure what wrong there. Maybe just a garbage clutch. That being said, I am going to drive my GT with the factory engine which still runs good, while bullding up my swap engine. I need a new clutch. If I get an upgraded clutch for my 2.8L, will that same clutch and flywheel work on the 3400? I am not looking for a SPEC clutch (had issues with them in the past), just something appropriate for the stock or slightly modified output of the 3400 ( assuming the clutch is interchangeable between the 2800 and 3400 engines.

Regading the 3400, any particular year/car I should look at?

Thanks for any and all advice! I appreciate it!
pmbrunelle FEB 17, 11:38 AM
Why a 3400 specifically, versus a 3500 or 3900?

Since you seem to be calling the Fiero L44 a 2800 (it was never designated that by GM, and it displaces 2837 cc), are you familiar with the three generations of the Chevrolet 60° V6 family, and its High Value descendants?

[This message has been edited by pmbrunelle (edited 02-17-2024).]

phils88GT FEB 17, 11:50 AM
Well, to be honest, I am not well versed in anything GM or the various codes for various engines. I know I want to replace the factory 2.8L and have a little more power without breaking the bank. I don’t know much about the 3.5 or 3.9. I just know that it seems from what I have read that the 3400 (whatever the code is for its various versions), seemed to be a more direct swap. If the 3.5 or 3.9 are not too difficult, I would consider them as well. The two things that concern me most are how much modification need to be done to the cradle to mount whichever engine and will my stock Getrag 5-speed bolt up to it? I don’t hammer or beat on the car, just want reliable, a boost in HP and something more modern.

Thanks
82-T/A [At Work] FEB 17, 01:30 PM

quote
Originally posted by phils88GT:

So after pondering what swap I want to do in my 88GT 5-speed. I think I have settled on the 3400 non-DOHC swap. I am not looking for massive amount of power, but an increase of any kind would be nice. Whatever motor I end up getting, I think I am going to drop the preparation a bit in preps for maybe a low boost turbo setup after a rebuild. What would be the best way to accomplish that? Is there much of an aftermarket for these engines? Would like to find a rod / piston combination to make for a more boost friendly compression ratio.

Second, I need a clutch. I actually need one now as whoever installed the clutch I have did something wrong because it slips like pad when you try to accelerate very hard. Not sure what wrong there. Maybe just a garbage clutch. That being said, I am going to drive my GT with the factory engine which still runs good, while bullding up my swap engine. I need a new clutch. If I get an upgraded clutch for my 2.8L, will that same clutch and flywheel work on the 3400? I am not looking for a SPEC clutch (had issues with them in the past), just something appropriate for the stock or slightly modified output of the 3400 ( assuming the clutch is interchangeable between the 2800 and 3400 engines.

Regading the 3400, any particular year/car I should look at?

Thanks for any and all advice! I appreciate it!




Hi Phil, like PMBrunnel said... make sure you're talking about the right block. There's several generations of V6/60.

The simple "drop-in" swap is the 3.4 Liter V6/60 that was in the Camaro / Firebird from 1993-1995. It's 160hp base, but realistically produces more in the Fiero because of less restriction and exhaust. It's quite simple to get 180-190 hp out of it based on doing things like port-matching the intake components, hogging out the exhaust manifolds, going with roller-rockers, and a few other odds and ends. That motor is called the DCC9 if you're looking for one on eBay or somewhere else.

Three links that have the DCC9 3.4 V6 available now... that drops right in:

https://www.jegs.com/i/ATK-...es/059/DCC9/10002/-1
https://www.napaonline.com/en/p/ATKDCC9
https://www.autozone.com/po...gine-dcc9/561355_0_0


Note, the ONLY modification you'll need to do is:
- Drill a hole for the second starter bolt.
- Tap the existing hole for the other starter bolt.
- Get larger injectors (17lb injectors instead of your 15lb ones)
- A plumbing adapter for the oil pressure sensor.

... everything else cane be used from your old Fiero... and I mean everything (including your flywheel because it's internally balanced, so you can re-use your flywheel).

Everything above that you need to get for tapping / drilling is available as a fool-proof "jig" that you can get from Rodney Dickman, here:

$97.00 Starter Drilling / Tapping Jig (with everything): https://rodneydickman.com/p....php?products_id=194
$5.89 Fitting / adapter: https://rodneydickman.com/p....php?products_id=193


The "3400" as you're calling it, is the next generation of GM V6/60 motors. These are the ones that were found in the Pontiac GrandAms, and even some of the Pontiac Grand Prixs. They're a better block, but there are a bunch of things you'll need to change in order for it to work. You can go with the old style heads, and then re-use the intake and everything, but you have to order a bunch of other parts related to the valve train because it uses a roller cam. It's not a simple swap, to be honest... and while it is a smoother motor, the only thing it really shares with the old engine is the layout and the motor mount locations.

There's the newer motors too... which require everything to be swapped over including the ECM and stuff.
pmbrunelle FEB 17, 06:16 PM
OP should decide if he wants a "Fiero-look" engine with the Fiero heads / intake / lower power / bolt-on install, or if he wants a newer engine with aluminium heads / more power / install involving custom work.

The direction OP wants to take here is unclear to me.

Anything up to and including the 3500 LX9 can be easily dressed up in the "Fiero-look" hardware. A roller lifter block does not add much difficulty, besides needing pushrods of a slightly different length (available from vendors such as Summit Racing) than stock Fiero, but required pushrod length should be verified when assembling a pushrod engine like this regardless.

With the Fiero-look hardware, you will more or less increase peak torque proportionally with displacement, but peak hp should not change much, because you still have the same restriction in the heads. The later aluminium heads have much better power potential out of the box. The king daddy 3900 LZ9 makes 240 hp stock, so that's pretty nice and something to consider.

In the Generation 1 iron-head engines, the combustion chamber is formed with a large volume in the head, and a flat-top (or low-dish) piston. In the Generation 2 and up engines, the combustion chamber is formed with a smaller volume in the head, and a deeper-dish piston. Combining an early head with a later piston results in a lowered compression ratio; I have this setup on my Fiero, and I have never heard it knock once (running up to 15 psi turbo boost). Later aluminium head engines can run boost too, without needing to reduce the compression ratio, but I don't have experience with this.

1988 V6 Fiero flywheel + clutch can be used (in terms of physically fitting) on any 60° V6 or High Value V6 if you want to use your Getrag. Torque capacity of the selected clutch needs to be compared with expected torque generation of the engine.

[This message has been edited by pmbrunelle (edited 02-17-2024).]

phils88GT FEB 17, 08:39 PM
Thank you for that information. I really appreciate that! To clarify my intent, when it comes to anything needing to have the Fiero look, I could care less. I am no purist when it comes to the power plant. I want to make a good amount of power, starting out naturally aspirated and eventually going with a turbo for more power. Like I said, staying with the factory intake, etc, doesn’t matter to me in the least.

So what engine should I be looking from the 3400 family? I would like the stronger bottom end with 8-ish compression. I know there are more facets to this, but that is all
I have for now.

[This message has been edited by phils88GT (edited 02-17-2024).]

pmbrunelle FEB 17, 10:02 PM
If you're not a purist about having the car look original, then I think you should go to the 3900 LZ9.

I can't think of any advantages that make the 3400 LA1 (only the LA1 carries the "3400" designation from GM) a better choice than the 3900 LZ9 for installation in a Fiero.

The LZ9 is the king; the culmination of the development of the 60° V6 / High Value family. LZ9s are readily available from junkyards, so why not go for one?

See here for dyno results of a stock LZ9 with a turbo:
https://www.realfierotech.c...iewtopic.php?t=21854

They can take some moderate boost without modifications.
phils88GT FEB 17, 10:20 PM
Thanks for that info! What kind of changes to the mounting to the 88 cradle need to be done? What kind of cars use the LZ9? Is the long block good as it is or do anymore need to be done?

Thanks again!
pmbrunelle FEB 18, 12:44 PM
You shouldn't need to modify the cradle.

The rubber engine mount at the front of the engine can remain stock-style, but you may need a custom bracket to connect the rubber mount to the engine.

ericjon262 is working on a bracket for this:
https://realfierotech.com/viewtopic.php?t=21987

To know which cars use the LZ9, you should try wikipedia.

From wikipedia, find an application that used the LZ9, and then perform a search for the engine assembly using car-part.com. The search results will show you the junkyards (the ones affiliated with car-part.com) with LZ9s.
82-T/A [At Work] FEB 18, 03:37 PM
Only thing you want to consider is if you go beyond the 3.4 engine (the one I mentioned above), you're going to need to get the ECM / computer with the engine you're swapping in. Me personally, I think the v6/60 is a really, really smooth running engine, and the newer ones with the roller cams can produce a lot of power and still give you a nice rumble while also running smooth and not obnoxious like an old small block will. But you'll definitely need a whole new ECM / computer. You can always try to use the one that came with the engine that you're swapping in, or you can go with something like a MegaSquirt or MicroSquirt, or some other aftermarket ECM system.