2.8 with a turbo? Bad idea? Motor performance thread (Page 2/3)
Honest Don AUG 26, 02:05 PM

quote
Originally posted by La fiera:


Nice engine bay! If you do little short pulls and drive it conservative it'll be a nice show car and give you lots of satisfaction. If you push it and for example take it
to a track day weekend I can guarantee you you'll be sharing the front seat with Bubba, the tow truck driver giving you and your car a ride home.
I'm telling you from my own experience. My N/A 2.8 had 173WHP @ 6000rpms and with the bad designed oiling system it was just a matter of time before it showed its flaws.
Another advantage for using the 3.4 over the 2.8 for turbocharging is the difference in rod ratios.



Thanks! I did the turbo back in 08-09. There have been a few hiccups along the way, but mostly nothing catastrophic so far. It's just a beat-around-town car with the occasional visit to the local 1/8th mile.

Power drops off around 5000rpm so I try not to shift too much higher than that. I actually had to get into the governor and move the shift points down a bit. As the boost went up, so did my engine rpm at the shift thanks to convertor slip.

[This message has been edited by Honest Don (edited 08-26-2020).]

Dennis LaGrua AUG 26, 03:49 PM

quote
Originally posted by Blacktree:

There are a few things that can make a turbocharged 2.8 V6 problematic. For example, it doesn't have a knock sensor. So if it runs lean, or has too much spark advance, you'll probably melt pistons. It also has no provision for electronic ignition. You can run low boost with a distributer, but it will tax the ignition system. Also, the bottom-end oiling in the 2.8 is marginal. The bottom end shares oil flow with the lifters on one side of the engine.

To install a turbo, and do it right, you'll need to address those issues. So in addition to the turbo upgrade, you'll also be retrofitting a knock sensor and electronic ignition, and modifying the crankshaft to improve oiling. Unfortunately, there's nothing you can do about the shared oil flow. That's built into the engine block.

You'll also need a different ECU. But that's true for just about any swap.

In later versions of the 60-degree V6, all those problems are addressed. They have knock sensors, electronic ignition, and better bottom-end oiling. This IMO is the main reason to trade up to a 3.4 V6. It's only a minor power upgrade, but a big durability upgrade. And if you use one of the 3100 / 3400 V6 engines, they also have reinforced main bearing caps, and roller lifters.

So if you're serious about the turbo upgrade, I would suggest getting a short block from a 3.4 or 3400, and build on that. It'll still look like the original engine, to the untrained eye. But it'll be much more durable, with more power potential.




The solution for adding a knock sensor is to use the 85 Fiero ECM. Thats the only year that contains the knock sensor interface. You'll need the GM Knock sensor, the ESC module (basically an A to D converter) and wires to connect everything together to feed the ECM input pins. Then you must go to the prom chips program, and check the knock sensor feature flag switch to on. Its not that hard to do. I'll try to post the diagram later tonight.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Blacktree AUG 26, 05:27 PM

quote
Originally posted by Dennis LaGrua: The solution for adding a knock sensor is to use the 85 Fiero ECM.


Yes, I know it has knock sensor input. But the stock Fiero ECM is slow. By the time it reacts to the knock sensor input, the damage is already done. Plus it doesn't have provisions for DIS, or WBO2, or boost control.
pmbrunelle AUG 26, 06:30 PM

quote
Originally posted by Blacktree:

Yes, I know it has knock sensor input. But the stock Fiero ECM is slow. By the time it reacts to the knock sensor input, the damage is already done. Plus it doesn't have provisions for DIS, or WBO2, or boost control.



If the Fiero ECM isn't fancy enough for your tastes, nothing stops you from using an aftermarket (or other) computer.

The MegaSquirt 3 I have on my Fiero supports all the aforementioned features.
sourmash AUG 26, 09:51 PM
No use in keeping the "original" looking engine when the big turbocharger right there screams I'M FAR FROM ORIGINAL.

Don't waste your time with the 2.8. And I sure wouldn't want to be held to very low boost. My slow diesel truck is held to 10. weak.
pmbrunelle AUG 26, 10:58 PM

quote
Originally posted by sourmash:
No use in keeping the "original" looking engine when the big turbocharger right there screams I'M FAR FROM ORIGINAL.



A turbo obviously doesn't look original to Fiero people, but if I imagine what a top-level turbocharged version of Fiero would look like if GM (or Ferrari) built it in the 80s, I think it's cool to go for that look. Or the look of a 80s tuner who modified the car with the parts available at the time.

So not original, but still retro-style. Turbos were around in the 80s; COP and large plastic engine covers were not.

If you throw away the retro, a part of the Fiero's charm goes away with it. Obviously not everyone thinks this way; there are some who enjoy modernizing their Fieros, and that's fine too.
Honest Don AUG 26, 11:58 PM

quote
Originally posted by sourmash:

No use in keeping the "original" looking engine when the big turbocharger right there screams I'M FAR FROM ORIGINAL.

Don't waste your time with the 2.8. And I sure wouldn't want to be held to very low boost. My slow diesel truck is held to 10. weak.



Mine is the original engine, not “original looking.”


What’s “very low” boost?
countach711 SEP 01, 08:23 PM
Mine has a turbo on it and it goes pretty good compared to a stock motor. It also has an MSD ignition box to deal with detonation.
sourmash SEP 01, 11:25 PM

quote
Originally posted by Honest Don:


Mine is the original engine, not “original looking.”[/quote[


What’s “very low” boost?



I was replying to his proposal. He doesn't seem confused though.

[This message has been edited by sourmash (edited 09-01-2020).]

sourmash SEP 01, 11:43 PM

quote
Originally posted by pmbrunelle:


A turbo obviously doesn't look original to Fiero people, but if I imagine what a top-level turbocharged version of Fiero would look like if GM (or Ferrari) built it in the 80s, I think it's cool to go for that look. Or the look of a 80s tuner who modified the car with the parts available at the time.

So not original, but still retro-style. Turbos were around in the 80s; COP and large plastic engine covers were not.

If you throw away the retro, a part of the Fiero's charm goes away with it. Obviously not everyone thinks this way; there are some who enjoy modernizing their Fieros, and that's fine too.



I daily drove a 1979 turbo Capri RS 2.3L in the early 1980s. I've had several turbo factory cars from 1981 to 1988 and shortened the waste gate rod on them to add some boost. They detonated some. My 1983 I added an intercooler, larger TB and larger exhaust to run about 15psi reliably with an adjustable pop-off valve.

If a person plans to go through the engine then starting with a 3.4 or even going with the 3x00 can be made to look stock. Really it's silly to debate. We aren't going to change minds and it's just daydreaming. Since a turbo Fiero wasn't made what's the purpose of limiting to the stock 2.8 if you're tearing it down? You can have more and it still look the same.