It has been a long time since I have posted here. Sadly this is due to the fact I have sold my 1988 formula. Don't worry though I will be buying another Fiero soon enough lol. Lately I've been thinking a lot about the super duty 4 and what it would be like to have in a Fiero. Besides the cost and everything like that, what are these engines like to run? are they a low RPM mule? or do you have to rev them really high to get any real power? I Know the engines are quite customizable and you can really make it how you want, but I'm curious about how the engine would behave in a Fiero in general. one would assume that a engine would behave in a similar way no matter what you do to it.
My other thought is: how would you mount this into a Fiero? would it bolt into the stock iron duke motor mounts?
And one last thing is I have also found out that you can indeed bolt a super duty 4 head onto a iron duke and it is still a usable engine.
i dont know how much validity to attatch to this but as i have read it when i was thinking about a super duty the only real super duty Fiero engines were in the original indy cars from 84 when it was the pace car, there were only 4 of them ever made and gm still has all 4 like i said dont know how much truth there is to that but it was a gm exec that saying this in an interview i watched about fieros
Manufacture of super duty engines was carried on by Kansas Racing products so there were quite a few made. I do not know how many were produced by GM but it was enough for the actual pace cars and to support a pretty extensive racing program. The super duty head will not fit on an iron duke from everything I have read.
This engine was never put in to a production Fiero.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
The SD4 engine was never offered in a Pontiac production vehicle. But everything was available through GM/Pontiac Performance Parts and the engine was used in many race series. I bought the Edelbrock 4-bbl intake manifold and Edelbrock PONTIAC valve cover through GM dealership.
The SD4 head will bolt to the Duke block after modifications to the block have been made. But you will still have a weaker block and internals limiting you to the Duke's 4500rpm redline. On the other hand, the SD4 block and forged internals are good for 10,000rpm.
The SD4 can be completely steetable, depending on how you build it as with any engine. With solid lifters, redline is usually held at a conservative 8,000rpm. Hydraulic lifters will limit you to about 6200rpm when you encounter valve float.
With my SD4 engine, I have a bit of a lumpy idle and gear whine but it has lots of torque and pulls strong from idle to redline. I've taken it on city and highways drives since I've built it. On the highway I average 36 mpg (30 mpg to US gallon).
GM never sold an SD4 'engine'. They sold all of the components to build your own engine. Block, Crank, Heads, Intake all 'sold separately'. So you will probably never find 2 identical engines. Also, the blocks came in a couple of different flavors. Early blocks had 3 bearing cams while later ones had 5 'roller' bearings. It is very very difficult to find a roller bearing cam.
As Fierosound said, yes, this engine can be very streetable, if you can find a non-racing cam. I have one in my 84 Fiero. The SD4 is very loud. Mine has straight cut timing gears and solid lifters. It make for a very noisy engine.
Many SD4's were used in the NASCAR Goodys Dash series. They were also used midget car racing. Point being the cams were made for high RPM racing, not low end torque. So you'd need the cam re-ground for street use.
The SD4 engine is a cool engine to have if you have an Indy Pace Car, otherwise, I probably won't suggest going this route. If I were doing another swap, I'd most likely go the 3.1-3.4 swap or a 3800 rather than do the SD4 again. Going with a production V6 engine, you can get close to the same power as the SD4, and it will be a smoother running and quieter engine.
Well, I really like them in the fieros mainly for the historical factor. Does anyone know if the mounting brackets are the same as the iron duke?
SD4 block mounts using stock Duke mounts with no problems, with the exception of the Dog Bone.
Most SD4's (which were used for racing) don't have the stock oil pan, and many have a different accessory/belt configuration that would have to be switched back to Duke. Just throwing out a couple of challenges you might face.
Does anyone know if the mounting brackets are the same as the iron duke?
The front motor mount bracket and all accessory brackets bolt up as stock. My '84 Indy has A/C compressor (not installed in this pic) and I used a '88 CS130 alternator.
[This message has been edited by fierosound (edited 04-15-2020).]
The front motor mount bracket and all accessory brackets bolt up as stock. My '84 Indy has A/C compressor (not installed in this pic) and I used a '88 CS130 alternator.
The Super Duty engines used in the Indy Pace cars put out like 270HP but at a high RPM level. From what I have read those engines had huge cam profiles, big Hilborn injectors and were not streetable. If you are considering using one in your Fiero you would need to build it down and perhaps get closer to 200HP. Thats still a decent number but I would consider the cost vs power factor before moving forward. As we still see the SD4's going for big bucks they may not be the best swap for you..
------------------ " 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 "
I used to have an SD4 in a Fiero. It was a relatively mild build, and also used some of the older pieces (iron heads and block). I figure it probably made about 200 HP. It was almost as quick as my 4.9. But it was loud. Even through a stock dual outlet muffler. I sold the car a couple of years ago, but I wish I hadn't.
but it has lots of torque and pulls strong from idle to redline. 
