So I just bought an 84 fiero, the engines totally crapped which is fine by me because I was planning on swapping the engine anyway.
The main issue is this, I have had the plan of buy an LS3 to swap out for the old iron duke, and to pair it up with an Audi 01e 6 speed trans. Which is all fine and dandy except that I might be a little over my head doing a longitudinal set up rather than the original FWD set up. I drew some stuff up and realized that I would need to push the rear axle back by around 5 inches if I wanted to do this. I would also have to extend the rear of the car by about 6 inches in order to keep the transmission from sticking out the back of the car. I was going to go with this set up because the trans is cheap and can handle my 800hp goal, it's also a set up not many have done before. I'm also a broke 16 yo who's never modded any drive train in any shape or form. Though this is not the first engine and trans build ive done, so don't worry about my skill set.
Long story short is this is going to end up being a very expensive set up. So im opting to switch for the LS4 FWD set up, but I can't find a maunal transmission that matches the LS4 bolt pattern, while also being able to handle 800hp. Most people say to go with the F40, which I would do but most people say they can only handle up to 300hp. Which is basically just the stock hp of any LS.
Are there any alternative transmission that can meet my goals? If not, would I be able to upgrade an F40 to handle the power I need?
Thanks much!
------------------ James Bird
[This message has been edited by BruhMans06 (edited 08-20-2023).]
Most people who want to do a longitudinal setup use an automatic transmission from an older Toronado but that will never handle 800hp. Just for info, see this webpage. http://www.nathanbittinger....fieroaddiction/sbc-l
Most people who want to do a longitudinal setup use an automatic transmission from an older Toronado but that will never handle 800hp. Just for info, see this webpage. http://www.nathanbittinger....fieroaddiction/sbc-l
Yeah I thought of this awhile ago until I realized it came out of a low hp Toronado from the 60s, this would be one of the easiest swap to do but I want something that would be able to hold up to the power of an LS
After a bit of thought I realized how stupid I sound trying to get 800hp with an LS on a weak 84 fiero. The car would probably fold itself under that so im wondering if I should mod the LS at all, or if I should just keep it stock as a stock lS4 already has 300 hp which would be pretty fantastic for a car of this weight and size. I'm kind of new to this so I don't know what the hell I'm doing.
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
After a bit of thought I realized how stupid I sound trying to get 800hp with an LS on a weak 84 fiero. The car would probably fold itself under that so im wondering if I should mod the LS at all, or if I should just keep it stock as a stock lS4 already has 300 hp which would be pretty fantastic for a car of this weight and size. I'm kind of new to this so I don't know what the hell I'm doing.
If we're talking about the same Toronado / Cadillac transmission... that's the Th-425... which is basically a Th-400 internals into a configuration where-as there is no driveshaft between the engine and transmission. It's still longitudinally mounted like Spoon posted... it looks cool, but my personal opinion is that it kind of defeats what the purpose of the Fiero is.
There are plenty of ways to swap in an LS motor though. I think you could easily do a 4T65E (4 for 4-speed, T for transverse, E for electronically controlled, 65 is the series and is the heavy-duty version). It can handle pretty much any LS engine you throw at it.
Also, I wouldn't worry about the Fiero chassis. So long as it's not rusted, and it's solid... the Fiero chassis can more than handle a V8 power-plant. The Fiero tied for first place with the Volvo 240 for best front and rear crash tested vehicle... it got 5-Stars. The chassis has what is called a "steel space frame," which is rock solid, and way more rigid than a mono-style chassis with a subframe connected to it. You literally don't have to do anything to the chassis to reinforce it... particularly because all the torsional effects are mostly on the subframe... which is solid. You can reinforce it if you want, but the biggest thing will be welding in some good motor mounts.
My biggest concern with having an engine that massive (my opinion)... is getting something this light to properly adhere to the ground, AND be able to stop as well. The Fiero is not very heavy... 2,500-2,700 pounds depending on options and engine. I don't know what the all aluminum LS motors weight, but an assembled duke is about 500 pounds. I think the LS motor will weigh a little bit less ...?
You'd really want to put on significantly stronger brakes.
The factory brakes for an 84-87 are barely adequate for the V6 that came stock in that car. As a teen, I used to thrash my Fiero and the disc brakes would be glowing red hot by the time I got home. So you really, really need better brakes. You'll also want much better tires, and probably want to do something about the suspension.
Basically, all of this is to say the chassis is not your problem... it'll be about making sure the car is safe after adding that much low-end power to it.
[This message has been edited by 82-T/A [At Work] (edited 08-21-2023).]
I personally would start out with a medium engine- say 200 hp, and then work my way up...Too much power in a mid-engine chassis can be a bit of a problem. Fieros (And all mid-engine cars) have a situation called Drop-Throttle-Oversteer (DTO)....You enter a turn and realize you are too fast, so you cut the throttle and the tail comes around on you...Killed a lot of people in early 911 Porsche's.
Also, when you are jacking the FIERO up and working underneath you need to be very careful- We lost a very nice guy who'd just started working on his Fiero- Wife came home and found him crushed under the car....Always check to make sure your jack-stands are solid and the car stable- always use blocks on both ground wheels Front & Back of tires- and re-check after car is ON the jack-stands. Here is a diagram of where to jack and where to support the car;
[This message has been edited by cvxjet (edited 08-21-2023).]
I personally would start out with a medium engine- say 200 hp, and then work my way up...Too much power in a mid-engine chassis can be a bit of a problem. Fieros (And all mid-engine cars) have a situation called Drop-Throttle-Oversteer (DTO)....You enter a turn and realize you are too fast, so you cut the throttle and the tail comes around on you...Killed a lot of people in early 911 Porsche's.
Also, when you are jacking the FIERO up and working underneath you need to be very careful- We lost a very nice guy who'd just started working on his Fiero- Wife came home and found him crushed under the car....Always check to make sure your jack-stands are solid and the car stable- always use blocks on both ground wheels Front & Back of tires- and re-check after car is ON the jack-stands. Here is a diagram of where to jack and where to support the car;
That's valid, I didn't think about the snap oversteer issue. I'm gonna throw a stock iron duke back in the car until I can afford to buy a new engine. I also won't be driving it hard with the LS until I fully trust my ability to drive the car. I'll probably baby the car for about a year or until I've passed the break in period. I doubt ill get 800hp anyway. I'm also planning on adding some rear aero and I'll keep the rear suspension softer (obviously stiffer than stock). I didn't realize this was an issue until you mentioned it to me so I thank you very much for that and I'll definitely take it into account on how I should build this
Originally posted by 82-T/A [At Work]: If we're talking about the same Toronado / Cadillac transmission... that's the Th-425... which is basically a Th-400 internals into a configuration where-as there is no driveshaft between the engine and transmission. It's still longitudinally mounted like Spoon posted... it looks cool, but my personal opinion is that it kind of defeats what the purpose of the Fiero is.
There are plenty of ways to swap in an LS motor though. I think you could easily do a 4T65E (4 for 4-speed, T for transverse, E for electronically controlled, 65 is the series and is the heavy-duty version). It can handle pretty much any LS engine you throw at it.
Also, I wouldn't worry about the Fiero chassis. So long as it's not rusted, and it's solid... the Fiero chassis can more than handle a V8 power-plant. The Fiero tied for first place with the Volvo 240 for best front and rear crash tested vehicle... it got 5-Stars. The chassis has what is called a "steel space frame," which is rock solid, and way more rigid than a mono-style chassis with a subframe connected to it. You literally don't have to do anything to the chassis to reinforce it... particularly because all the torsional effects are mostly on the subframe... which is solid. You can reinforce it if you want, but the biggest thing will be welding in some good motor mounts.
My biggest concern with having an engine that massive (my opinion)... is getting something this light to properly adhere to the ground, AND be able to stop as well. The Fiero is not very heavy... 2,500-2,700 pounds depending on options and engine. I don't know what the all aluminum LS motors weight, but an assembled duke is about 500 pounds. I think the LS motor will weigh a little bit less ...?
You'd really want to put on significantly stronger brakes.
The factory brakes for an 84-87 are barely adequate for the V6 that came stock in that car. As a teen, I used to thrash my Fiero and the disc brakes would be glowing red hot by the time I got home. So you really, really need better brakes. You'll also want much better tires, and probably want to do something about the suspension.
Basically, all of this is to say the chassis is not your problem... it'll be about making sure the car is safe after adding that much low-end power to it.
I will be upgrading the suspention and brakes so it can handle the power, i already noticed how absurdly small the discs were stock anyway. I'll probably barely even scratch 600 hp and probably will only make 500 as I'm still debating whether or not I want to supercharge it. I'll probably just start with a stage 2 cam and a stiffer valve train. I just want the car and trans to be as prepared as possible for any power so I don't accidentally **** something up. It's just me being stingy and overprepared for what ever happens. Thanks much for the input.
I bought my 85 SE V-6 new...My father, who had been into British sports cars (Look up Jowett Jupiter) before I came along and ruined his life, drove a Corvair for my first 4 years....He warned me about the DTO...Told me to just "get back on the throttle a bit"....
I was hot dogging getting on the freeway but had to cut the throttle in mid-turn and the tail came around- Remembered what he had said and gave it some throttle....Survived....
Years later, I was working at NAS Alameda and living in San Leandro- every day I would drive home on I880 and get off at Marina blvd...The offramp had a bit of a kink in it- Instead of turning the wheel, I would chop the throttle which would kick the tail out slightly....Basically, I was practicing dealing with the DTO every day.
Once, as I was entering that turn, a BMW 3 series started tail-gating me...So I dropped a gear and "Went for it"...when I cut the throttle it really came around, and as I got back on it, it drifted thru the turn at quite an angle....And the BMW disappeared...at the next intersection I stopped and was adjusting the stereo and finally here comes Mr. BMW....I looked over at him- WHITE as a SHEET!
You should always learn how each of your vehicle reacts to situations- experiment a bit so you know what it will do.
[This message has been edited by cvxjet (edited 08-21-2023).]
Um, well to start with, I'm not here to step on anyone's toes, but lets get back down to earth, shall we. Everyone talks about wanting 800 hp, but the truth is that 99.99% of EVERYONE on this planet couldn't handle a mid-engine car with more than 400 hp without traction control (that will automatically cut engine output when the wheels spin) and anti-lock brakes. The Fiero has neither. Even if you did get to 400hp, that squirrely car would kill you before your 19th birthday.
A mid-engine car has more weight in the rear than in the front. I bought my first Fiero when I was 26 and quickly spun it twice on wet roads with just that same wimpy 98hp iron duke that's in your car. Even higher torque will help the rear tires break loose that much easier and you'll wake up either in a ditch or in the morgue. So realize that you are not a real race car driver and probably never will be. None of us will be. Modify your car with that fact in mind.
You mentioned the "wimpy" Olds and Cadillac engines of the early '60s. Hmmm, where are you getting your data? The TH-425 transmission was installed from 1966-1978 only in the 4000 lbs Olds Toronado, Cadillac Eldorado, and the 12,000 lbs GMC motorhome. The smallest engine used in any of these vehicles was the Olds 407. The Cadillac 500 put out 550 lbs-ft torque all day long. Not so whimpy after all. But, it's still a horrible choice for a Fiero simply because of its very high weight and the extensive mods necessary to get it to work. If you were an experienced welder, machinist, and fabricator (all at the same time) you might be able to pull that off, but at 16 you couldn't possibly be one of those professionals, let alone all three. It's also only a 3-speed automatic with no overdrive gear. Not a great choice. Did I mention it's very heavy? It's not a great idea to add more weight to the rear of a mid-engine car that already has a rear weight bias unless you enjoy looking like a fool when you lose control of you car (again).
The Cadillac 4t80 is a great transverse automatic transmission that is now dirt cheap and made to handle the high torque of a 300hp Northstar V8, but it is also quite heavy and still needs plenty of modifications to work with an ls4 in a Fiero. It may be a 4-speed with overdrive, but it's still not a good choice for a Fiero.
If you ask the owner of any 2005-2008 Impala SS, Monte Carlo SS, or Grand Prix GTP what the weakest link is in their cars, they will gladly tell you its the 4T65-HD transmission. It doesn't so much break as it wears out much quicker than anticipated behind the stock 303hp ls4 V8. Please, go to their forum and just ask.
Having said that, it's by far the best automatic transmission for our Fieros because of its cost, weight, adaptability, torque capability, upgradability, and cost. Yes, I listed cost twice. As a broke 16 year old, your cost should be everything to you. Speaking of which, the amount of fabrication work (and cost) just to get an LS4 (even with this matched tranny) to work in a Fiero is rather exorbitant. It's not necessarily the cost of the engine and/or tyranny that breaks the bank. It's the cost of all those pieces and parts you'll need to pull it off.
As for standard transmissiins, the F40 is a great choice, but it is quite rare an expensive to aquire. Then there is a whole list of modifications necessary to just mount it into a Fiero and even more to adapt it to an ls4.
A much, much, much better choice for a stick is the 1985-86 Fiero 4-speed stick that came with V6 Fieros before the Getrag 5-speed became available. My understanding is that the 4-speed used with the V6 can handle more torque than the Getrag 5-speed.
Don't even look at any 4- or 5-soeed standard transmission mated to any 4 cylinder iron duke. These were very low torque Isuzu transmissions that will break behind the torque of a V8.
There is a great alternative that you should consider. Buying a running front-wheel-drive car with a supercharged Series II 3.8 V6 engine is not only doable, but it's cheap and relatively easy to swap into a Fiero along with its matching transmission. These vehicles are around 20 years old now and therefore very cheap for one that is still running and driving. Yes it's less than 250 hp, but it will retain your front/rear weight ballance, will be affordable, yet still give you tons of fun.
I also won't be driving it hard with the LS until I fully trust my ability to drive the car. I'll probably baby the car for about a year or until I've passed the break in period.
Don't kid yourself. You may not put the pedal to the metal the first few times out, but I guarantee there's no way you or anyone else is going to curb their "enthusiasm" for a full year. At some point, you'll be wanting to see what she does.
I was no different 50 years ago. I was fortunate to not have wrapped my big block Chevy(s) around a pole... and I consider myself a good driver. Horsepower and speed are as intoxicating as any drug... and potentially just as deadly.
Also, when you are jacking the FIERO up and working underneath you need to be very careful- We lost a very nice guy who'd just started working on his Fiero- Wife came home and found him crushed under the car...
That was truly heartbreaking. Probably the saddest turn of events I've ever experienced in the 24 years I've been a member here.
Yeah I bit over my head here, but I'll keep trying my best. I know how to weld (not the greatest obviously) and I just want a car to spend my time on as I've had many cars I've worked on come and go in the blink of an eye. So I want a car I can work on for years without running out of things to improve. That's the main reason I bought this car. I'll build the v8 up over time. I won't go all out at once, ill probably just start out with a cammed v8 that probably put out less than 400 (which i now realize is a lot for a little car like this, thanks to all of yalls input) I'll try my best not to be an idiot when driving this car and I now realize that all of this stuff is not something to mess around with when I'm out on the road. I always make sure to keep the rims I remove under the car so if the jacks do fail the car will land on the rims and I won't immediately be crushed to death.
Thank yall very much for all of your input. I'm going to continue this project as I originally planned but I'm going to make this a very long term project. Immediately going to start off by putting a "new" iron duke in back in the car and drive that around until I can find the right trans and engine for me.
You mentioned the "wimpy" Olds and Cadillac engines of the early '60s. Hmmm, where are you getting your data? The TH-425 transmission was installed from 1966-1978 only in the 4000 lbs Olds Toronado, Cadillac Eldorado, and the 12,000 lbs GMC motorhome. The smallest engine used in any of these vehicles was the Olds 407. The Cadillac 500 put out 550 lbs-ft torque all day long. Not so whimpy after all. But, it's still a horrible choice for a Fiero simply because of its very high weight and the extensive mods necessary to get it to work. If you were an experienced welder, machinist, and fabricator (all at the same time) you might be able to pull that off, but at 16 you couldn't possibly be one of those professionals, let alone all three. It's also only a 3-speed automatic with no overdrive gear. Not a great choice. Did I mention it's very heavy? It's not a great idea to add more weight to the rear of a mid-engine car that already has a rear weight bias unless you enjoy looking like a fool when you lose control of you car (again).
I immediately take offense to the term "wimpy" and Oldsmobile in the same sentence! Hahaha...
I looked, and I don't think I saw where anyone said this, but I wanted to take this opportunity to mention how fantastic the Oldsmobile motors are. This is a 1969 Olds 455 Big Block that I bought for $250 bucks, in trade for a running LD9 TwinCam.
I brought it home looking like this ... dirty and nasty:
I love this engine so much that it's literally been sitting in a central Florida storage unit for the past 13 years, wrapped in a Moroso engine back with some dessicant packed in, and the cyl bores filled with oil. Who knows if it's still good... I don't even have a car to put it in anymore. Haha...
The main issue is this, I have had the plan of buy an LS3 to swap out for the old iron duke, and to pair it up with an Audi 01e 6 speed trans. Which is all fine and dandy except that I might be a little over my head doing a longitudinal set up rather than the original FWD set up. I drew some stuff up and realized that I would need to push the rear axle back by around 5 inches if I wanted to do this. I would also have to extend the rear of the car by about 6 inches in order to keep the transmission from sticking out the back of the car. I was going to go with this set up because the trans is cheap and can handle my 800hp goal, it's also a set up not many have done before.
Wow, that is actually really cool looking. It has Porsche 944 vibes going. I assume that's a 3rd-Gen F-body hatch lid that they've fabricated on. Really, really cool. I wonder how it drives. Is it getting the oxygen for the engine from the passenger compartment? I wonder what that must sound like back there...
Wow, that is actually really cool looking. It has Porsche 944 vibes going. I assume that's a 3rd-Gen F-body hatch lid that they've fabricated on. Really, really cool. I wonder how it drives. Is it getting the oxygen for the engine from the passenger compartment? I wonder what that must sound like back there...
Firewall, rear window etc. is all still intact like on any Fiero....
[This message has been edited by fierosound (edited 08-23-2023).]
It's easy to toss around figures like "800 HP", but step back for a minute, and think. There's a guy up in New England who is pushing the envelope, regarding LS4 installs. He is widely regarded as "THE MAN" regarding LS4 Fieros. He dynoed his car at the 40th. IIRC, it was making 564, to the wheels. So... maybe 640-650 at the crank? We're talking turbos, beadlock rims, drag tires, coil-overs, tubular suspension pieces, and other things. Lots of really exotic stuff. The car is purpose-built, and is a nice, complete package. I'll bet he's got a solid 30K in the car, if not more. Having said all of that, I believe it's also running an F40, although I could be mistaken.
Some other things he is working on are an LS4/4T80 swap, and an LS4/Acura NSX(?) 6 speed swap. (This car has a full cage, among other things.)
I don't mean to whiz all over your dreams, and I admire your enthusiasm, but please keep your feet on the ground.
[This message has been edited by Raydar (edited 08-24-2023).]
Firewall, rear window etc. is all still intact like on any Fiero....
Man, I really, really like that car. Honestly, and this is just my opinion, but I normally do not like it when people do custom stuff... it tends to just not be my thing. I prefer OEM look. Again, no one should be offended by it, it's just my opinion and I can absolutely see talent, effort, and style in almost anything that someone creates.
But this creation, I actually really really like it. Not that I make it a habit to do so, but I'm not finding any fault in the styling. If I was to build it the same (and had that level of skill and dedication), I'd probably build it exactly the same. Literally the only thing I'm not 100% on is the exhaust... I'd have probably kept it split like how the stock Fiero has it. But this was really well done, and the integration of the 3rd gen hatch really sets it off too... makes all the difference in the world.
quote
Originally posted by Raydar:
I don't mean to whiz all over your dreams, and I admire your enthusiasm, but please keep your feet on the ground.
Yeah, on this... my recommendation would be to get "a" LS motor installed ... like a solid basic crate motor. Then see how you like the performance and go from there. Anything after that point will not be too difficult since you'd already modified the subframe to handle an LS.
But this creation, I actually really really like it. Not that I make it a habit to do so, but I'm not finding any fault in the styling. If I was to build it the same (and had that level of skill and dedication), I'd probably build it exactly the same. Literally the only thing I'm not 100% on is the exhaust... I'd have probably kept it split like how the stock Fiero has it. But this was really well done, and the integration of the 3rd gen hatch really sets it off too... makes all the difference in the world.
I fully agree. I believe it was in the "Top 5" favorites people voted on at the 40th Anniversary Show.
Yeah I thought of this awhile ago until I realized it came out of a low hp Toronado from the 60s, this would be one of the easiest swap to do but I want something that would be able to hold up to the power of an LS
I mean the Toronado had a 455 that made 375HP and 510lb/ft, that is by no means a weak transmission.
