A 3.4 DOHC Build then... F40 Turbo (Page 2/57)
Fierobsessed FEB 04, 09:31 PM
Can't put anything passed you guys!

This is what I did about the manifold flip:

I didn't really mension it, but I did rebuild this engine. But I've had a 97 crate engine forever that I'm going to put into service, but with the old 94 heads. I need the older heads for compression and for the flipped manifolds. I Could make a plate to adapt a flipped 96-97 front manifold, but then I'd still have 9.7:1 which is a bit much.

[This message has been edited by Fierobsessed (edited 02-04-2013).]

Fierobsessed FEB 04, 10:27 PM
The joys of a 3.4 DOHC.

The 3.4 DOHC is a hodge podge of an engine. The bottom end of the 60ยบ the complex addition of DOHC heads that are driven by a chain and a belt. And it leaks. But on the plus side IT FLOWS. And boy does it. No other engine I have ever heard of takes to boost like this engine does. It doubles its horsepower at well under 1 bar of boost.

4 years with this engine, it ran great. Met my performance expectations time and time again. 26 MPG city (when driven like a wuss) normally 22 MPG City. 31 MPG highway with ease. But I did have some troubles. The engine had a ratteling noise, I never figured out what it was, I'm guessing its the timing chain tensioner. And it also ticked a lot when the oil was at the end of its life and I was ragging on it hard. I also needed to run 10W-30 as 5W-30 made the engine tick like crazy. Thicker oil was always better in this engine. And I chose synthetic. This may have been the single biggest mistake I made with this engine. It seems, that synthetic oil eats seals. The aluminum/silicone lined gaskets that sealed the heads to the cam carriers failed completely. I had oil coming out from everywhere. It appeared that the synthetic oil swelled the seals so much that they blew out. This is what prompted me to pull the car out of service to do the big upgrades, and I'll stay clear of the synthetic this time.

My 282 Getrag was also getting old, It had seen 247,000 miles of service, the last 30K with the 3.4 DOHC. It still works, but it tends to get a little noisy on long steep climbs at highway speeds. I figured it was time to put it to rest.
nitroheadz28 FEB 05, 02:00 AM
Very cool build sir, everything about your work looks factory
Joseph Upson FEB 05, 06:05 AM
It looks really good and I envy your toy (tool) collection. As a note to others intending to do a high output turbo motor with aspirations to exceed 400 hp, I would do a 3" exhaust start to finish except for dual outlets from the muffler. I had a tremendous obstruction to exh flow that I was not aware of although I suspected a little. I have a 3" pipe from the turbo that terminates into dual 2.25" inlet baffled 4" round mufflers. I also installed an electric cutout at the junction to bypass those mufflers. With the cutout closed boost pressure reached the 7 psi wastegate setting, upon opening the cutout I discovered it was actually being limited to 7 psi as boost pressure climbed another 3 psi by 5000 rpm with the cutout open. The exhaust note is too loud to run without a muffled option. That 3.4 will run higher rpm than what I'm cammed for and I don't see it needing any less flow than what my pushrod motor needs so keep that in mind.
tesmith66 FEB 05, 06:30 AM
Wow. Didn't know about the manifold flip covering up part of the port. Now I have to pull mine apart...

1986 SE Aero coupe.

3.4 DOHC swap is complete and running, now just have to finish the rest of the car...

Fierobsessed FEB 05, 09:07 AM

Originally posted by nitroheadz28:

Very cool build sir, everything about your work looks factory

Thanks! That was the goal! Make it look like it belonged in there.
Fierobsessed FEB 05, 09:18 AM

Originally posted by Joseph Upson:
I had a tremendous obstruction to exh flow that I was not aware of although I suspected a little
... I don't see it needing any less flow than what my pushrod motor needs so keep that in mind.

I absolutely agree. It's something I'm a bit worried about. At this moment in time my intention is to go 3" from the turbo outlet, throuh a 3" stock located catalytic converter, to the very same muffler I have been running all along, with the dual 2.25" outlet pipes. But I'm concerned about the muffler's ability to handle all that airflow, then the 2.25" outlet pipes ability to do the same. This engine already runs 2.25" straight out of the manifolds! My other condsideration, is that 100% of the exaust gets crammed to about a 1.25" circle within the turbo before it starts to funnel into the turbine itself. After that, a 3" outlet is like a playground. I bet that the catalytic converter itself is a bigger restriction then the muffler. But for the reason of sanity, I'm going to have a V-band flange connecting the muffler, so I can change it out later if I need to. Or, test without!
Fierobsessed FEB 05, 10:46 AM
Right after Thanksgiving this year, I got my car through inspection, and registered for another year of service, drove it home then the engine came out. I remember the engine being a lot cleaner when it went in, but I'm not overly concerned about that at this juncture.
Now for the fun stuff. Where do I put the turbo?

I thought long and hard about turbo placement. Since I wanted the exhaust to go forward first to a stock location cat, I knew that I would most likely have to go with something like this:

This is where the test fitting trials began. Right away I started by removing the old crossover tube, coolant neck, water bypass and fuel lines. This bought me some room to play with fitment, knowing that every thing I removed for test fitting will later need to be modified to work around the turbo system.

Next, I unbolted the 282 Getrag, and permanantly retired it from its very long life as my Fiero transmission. Perhaps It'll get a little rebuild and live on? I think it will! But I am done with 282's. I've moved on.

I removed the clutch, which much to my surpise was in absolutely perfect condition. The original machining on the fywheel, and pressure plate appeared untouched by the clutch for 30,000 miles. The clutch disk itself also was in this rather miraculous exactly as it was when I installed it condition. There was practically no dust in the bellhousing. Nice and clean. I can't say enough how pleased I was with this Clutchnet Kevlar Sprung disk. I highly reccomend this clutch!!!

I bolted up the F40 to the engine to see how I would do the shifter cables, and how that was going to effect my turbo placement and immediatly got to fabricating...

For shifter cables, I chose to use the one stock Select Cable like everyone else, and for the shift cable I had California Push-Pull make me the very same cable people have been getting for the F23 swap. This is my now, not so secret weapon!

For these brackets, I used some 1/8" X 2" flat stock, and a piece of 1/8" plate cut and drilled to match the bolt pattern around the shift mechanism. I made 3, 5/8" spacers to raise the plate up a little to clear a few things. Just some quick tack welds to start. I'll finish the welds much later.

I knew that since the turbo will go directly above the shift cables, that I wanted to make the shift cable bracket double as a turbo support, so I made the plate extra big in case I wanted to weld something to it later.

When I'm fabricating things, I always like to take stock on what are the Knowns, and the Unknowns. This way, I can keep working on the Knowns. And think about the Unknowns as I go, or put them off completely untill all the knowns are completed. I KNOW Im going to use an F40 Transmission. I KNOW that the shifter cables need to go where they have to. I also know that the turbo will be above the transmission. So this dictated what my work priorities were. It never makes sense to dive right into the unknowns, when you havn't even factored all the knowns in yet. You'll get yourself stuck when you realize... Oh, crap, this had to go here! And that there is no avoiding it, and that might mean starting from scratch.

So once the Shift cable bracket was completed, it was time to load the engine and transmission into the car for a test fit. A few things that I was looking for:
1. Will the transmission fit in the car with the engine placement as it was with the getrag?
2. Do I need to change the engine location?
3. Does the new shifter cable bracket interfere with anything?
4. Will the turbo fit at all?
5. What about the inevetible addition of an intercooler?
6. How will I plumb this nightmare?

Test fit.

Ok so this is roughly where the turbo will need to go. It looks like fitment isn't too bad!

I had a box of 2.5" charge pipe bends that I accidentally ordered a few years ago for a project, (that required 3" pipes) and I kept them knowing that I would most likely need them for my Fiero. I immediatly realized that the turbo compressor outlet could never face straight up, or route rearwards without hitting the strut tower and the decklid. I found that the U bend, with a 90 degree silicone coupler was the magic trick I was looking for to get the compressed air towards someplace useful, It curved right around the shift cables, and down through that spot just above the main frame rail, at the bottom of the strut tower. like this:

The other discovery was that I had to do a hard 90 out of the throttle body to avoid the decklid and run over the top of the air filter, then downwards by the trunk. My plumbing plan was starting to take some shape.

Sure, why not, that looks like a good spot. Easy acces to manifold vacuum too!

So with this picture, I found that I would need to make a sharp, over 90 bend to clear the firewall. I ordered a couple stainless 3" 180's and a super tight 90.

For me, cutting the trunk wasn't going to be an option I would entertain for this project. I figured I'd find a way to avoid that. So Now that I had my ideas on plumbing, I needed to find an appropriate intercooler. Naturally with the mid engine design, and the space requirements, I gravitated towards a Water to Air type. And the best placement I could find for it... Between the passenger side axle, and the cradle. I'll need to do some obvious heat shielding with this arrangement. But I think it'll work great!

Fierobsessed FEB 06, 04:42 PM
Once I had the exact tubo location figured out in that test fit, I pulled the engine back out and made a bracket to support the turbo in that spot. I added it to the shift cable bracket.

You can see that clearly the head to cam carrier gasket was leaking in this picture too.

This is the intercooler I wound up getting in a package deal with a pump and a front mount heat exchanger.

I spent a lot of time trying out various mounting positions for it.

In the end I found that it was just a little too thick to fit between the axle and the sway bar and with fittings, just a little too long to fit between the alternator and the transmission. So I picked up a smaller version of that intercooler.

The engine went back in again this time to play with the new intercooler and to build the down pipe. I started by welding the tight 90 to the V band flange, then welded a second piece to it to make it go slightly past 90 degrees. I needed it to clear the AC lines and the heat shield. Then a third piece to correct to the nearly straight down Looks like I hit the nail on the head with this pipe.

Love my TIG welder.

Engine back out

Still working on how to do the intercooler

Hudini FEB 06, 09:56 PM
Great build. Watching it closely. Have you tried placing the intercooler in place of the 180* bend after the compressor? That's where mine fit the best.