Michael Yount

iTrader: (1)

If you jump back to post #18 you’ll see some exhaust fab work. And then just a few pages back it changed when a turbo was added. No cats and not much room for them.

AspenW41

Thanks, Micheal. I'm just trying to solve problems ahead of time. The routing of the exhaust and including the converter around the subframe and the ls4 oil pan with the starter. Also whether or not to have the starter on the oil pan or on the bellhousing is also a thought here. I'm thinking on of holley's performance manifolds 2.56" might work on one side, and an ls7 manifold on the other side going into a y pipe into a 3" pipe might be the way to go here. 3" pipe generally can handle 300 hp, although cam and intake upgrades would make it even more difficult.

fieroguru

iTrader: (1)

Not sure if you are asking about the exhaust when the car was naturally aspirated or in its current turbo configuration.
When the car was Naturally Aspirated, I didn't run any cats, but I have used the same exhaust layout (center dump headers) with cats on a SBC in a Fiero swap.





Another option for Naturally Aspirated is to run the exhaust path just like the 2.8 V6 in a Fiero. Use the front LS4 manifold in the front as it already exits pointing at the transmission (similar to stock Fiero). Then modify a truck manifold to do the same on the rear. Use a Y pipe to connect them (like the Fiero 2.8). From there the exhaust is just like Fiero with a cat in front of the engine and muffler in the stock rear location. Here is the stock LS4 front manifold. The one on the bottom had the flange ground down to make it smooth for a V-band.

Here is the rear modified truck manifold. The modification was to make it exit horizontal vs at a 45 degree down. The manifold on the engine is the stock LS4 rear manifold.


The current turbo exhaust setup (using a custom fabbed rear manifold) has dual inline mufflers. The top 3.5" one could easily be a catalytic converter, if you want it to be.

AspenW41

Thanks for your help of the pictures on the various pictures on the exhaust setups. That is a BIG help. I was asking for normally aspirated form BTW.

AAIIIC

iTrader: (19)

According to MD's emissions testing page, anything older than '95 is exempt from testing (see the first line of Appendix C). You can still install cat(s), of course, but you don't have to worry about passing any emissions test.

AspenW41

Thanks for that, AAIIC. I didn't know they had exempted anything before 95". I just ASSumed they were just like Colorado's program where the emmission standard of what the drivetrain came with, is what the car had to have. Then again, we are taking a mid 2000s drivetrain and putting it in a fiero, SO the ls4 emission standard may take precidence here. So just to be safe and responsible, I will have to go with the drivetrains emmission standards.

AspenW41

just spoke with an emission referee in Mayland. They said because it was an 88 fiero, they would even test it. WOW, AAIIIC. You WERE correct. I had just figured the California's the grandfather of Colorado and Maryland emission program, it would be the same standard.

fieroguru

iTrader: (1)

I have been slacking on updates...

Finished welding up both knuckles:


Finished making the rack spacers. Since the rack had female threads, I found some tie rods with the same female thread pitch, and some 10.8 all thread, then all that was left was machining some hollow alumunum sleeves to dial in 5" of rack movement from lock to lock to match the Fiero rack.




Then reworked the rack brackets out of 1/8" to shed some weight from the earlier 3/16" ones.



At this time, I tried to buy the Brembo caliper for the other side so I could really finish up the front suspension and ran into supply chain issues. While these are from a car currently in production, there appears to be a shortage of them in stock at the moment.

At this point, I came to my senses and decided to get refocused on getting the car running. The car has a fully functioning front suspension, I doesn't need anything at the moment to work, and I can always swap the front suspension at a later date once the car is running.

Since the drivetrain was in the chasssis, it was a good time to figure out the cold side plumbing. Crude paint rendering:


Mocking up the tubing. With the 4" tube now clamped in place and clearing the strut tower, the rest can be fabbed up on the bench:



Also worked some more on the exhaust... When the car had the 3.55 final drive, it didn't have any noticeable resonance when cruising in 6th at 70 mph. When I swapped to the 3.091 final drive, the car was noticeably louder at 70 mph due to resonance and it dropped off as the car got to 80 mph. Since i am going with 3" exhaust, resonance will be worse, so I want to use a helmholtz 1/4 wavelength resonator and have used my prior observations of resonance rpm to help narrow down the expected length needed.


I had talked about using the cutout on the passenger exhaust tube to act as a resonator, but there is just too much pipe to fit in that area. Instead, I will route it parallel to the muffler between the muffler and cradle rail. Here it is setting in place. It is about 27 3/8" in length, which should work. It will come off the exhaust at the Y section where the 3.5" splits to dual 3" exhaust tubes.


Then moved on to fabbing up the exhaust tips:





One last thing before pulling the drivetrain for more bench work, was to locate the top of the struts so I could find a good home for the sway bar.




Then everything went back to the bench.




Then the sway bar mock up. The turbo forces the sway bar to be several inches lower than stock, which means it can't go over the axle any more. I ended up having to flip it over and run it below the axle and above the lateral links. Here is a stand to help dial in the location and will eventually hold the bar in place while I fabricate the sway bar brackets to the tubular cradle.

Full compression (also clears at full droop).


Clearance of the sway bar to the compressor housing:

Michael Yount

iTrader: (1)

Inspiring work!

AspenW41

I'm curious what power steering rack you went with on this build. I do remember a build on Fiero.nl using a Corvette Remanufactured ZR1 steering rack being also dead on, that only needed some fabbed up brackets on one side of the rack, because it was pretty much a dead on swap. There was a a build that did use a Camaro/Firebird steering rack as well, that needed a litte more fabing help to work. I'm sure your arms will thank you when your go to parallel park.

fieroguru

iTrader: (1)

I used a Camaro rack with 2.5 turns lock to lock. All racks (Camaro or Vette) need the inner tierod spacers to match the 88 Fiero rack overall length - my swap needed longer spacers as I moved the inner tie rod pivots outboard further to correct bump steer caused by the taller knuckles. The power steering upgrade isn't about steering effort (never had an issue with steering effort), it is all about the quicker ratio for autocrossing. 3.25 turns lock to lock isn't great when making hard 90 degree turns.

AspenW41

What generation/year of a Camaro rack, BTW?

Ramon Duvernay

ryeguy2006a

iTrader: (27)

I love seeing the updates on your build. Thanks for posting up all of the details. I'm going to look into the calculations for the Helmholtz resonator.

fieroguru

iTrader: (1)

Thanks guys!

4th gen.

fieroguru

iTrader: (1)

I finally figured it out and fabricated a workable mechanical water pump solution! It uses a $50 water pump insert (pulley flange, shaft, seals, bearings, and impeller), I just had to make the housing for it, and rework all the alternator, AC, and tensioner brackets.

LSswap

Hat's off to you. And I thought I had a challenge fitting an ls turbo in a tight C3 Vette engine bay.

Ls7colorado

iTrader: (3)

This is amazing, Ive gotta go back and see if theres some videos of this thing!!

Jimbo1367

Just imagine how much a shop would charge him to do this conversion/turbo swap. I bet most wouldn’t even do it.

G Atsma

..... much less know how....

fieroguru

iTrader: (1)

Thanks guys!

Fabbed up the sway bar mounts:




The 369SXE is said to be better suited for small cube, high boost applications. General internet theory is that it is due to the much smaller gap in the housing for the air off the wheel to exit.
The gap is quite small being 0.225 to 0.25" and the older versions were about twice as large from other pictures.



So while everyone thinks the main issue with the 369sxe is the gap, I haven't ever seen someone try to modify it. So why not... went ahead and opened that section of the compressor housing up to .350".



The cover also had the hose barb outlet section cut off and machined flat with a pilot bore to accept a V-band:



Last thing I did this weekend was tack together the cold (non-I/C = warm) side. V-band off the compressor, silicone coupler at the TB. There is a honeycomb airflow straightener about 1.5" after the diameter transition. The LS7 MAF will be after it and before the bend.