In November of 2015 I bought a black 1984 Fiero SE. After failing several times to have it shipped from NY to WI, my friend and I took a road trip and trailered it back during a severe snow storm. The car had been sitting for some time, the engine had seized, the tires had all dry rotted, but the car was 95% complete. It has bad paint that has gotten worse in the past 7 years, there are a few damaged body parts, and a missing headlight motor. I collected some parts over the last few years, but overall have avoided major work on it until recently. The big selling point for the car for me was that it had a 2.7L Super Duty engine in it and a pile of receipts from the build, and only 3,330 miles on the Odometer! I won the Ebay auction for $1,575, and had it in my possession by the end of February 2016. In my excitement for finding such a great deal I tried to compile all the information that I could about building SD4 engines. I bought magazines that talked about the engines, and scoured the internet. There is not a lot of open discussion on building these motors but enough data to pull something together. I was able to get at least a solid plan together for a more performance oriented engine build.
I'll follow up with more posts detailing my progress so far and the information I've gathered.
Background on the SD4 (or Super Duty Four) engine program with regard to blocks and heads as I have ascertained from my reading:
The Super Duty Four program started out with John Callies at Pontiac, and it came from the need for the Fiero to be the Indy 500 Pace Car. John’s Interview with Total Seal Piston rings is probably the best 1st source for information on the program. Find it here: https://www.youtube.com/watch?v=2qkJu83XIPk, I heard him speak at the 30th Fiero Anniversary show, and he is a great teller of stories.
Pontiac made the parts designed for the program available to consumers through their dealer network, and had many aftermarket companies produce parts as well, which were advertised through the Pontiac Performance Plus publications. This engine wasn’t available as an assembled unit, each one is uniquely built with an application in mind, by random engine builders throughout the country. Vanderley Engineering built the engines used in the Pontiac GTU and GTP-L race programs.
I have two versions of the Build Instruction booklet put out by Pontiac and Hot Rod Magazine at this time, the 1983 version (the same as the pdf version which is shared often), which covers the specific block I have very well, but the head detailed in that book (GM# 10027776, with casting number 10027775) is not very common. This head was quickly replaced by the 10031323 and 10031322 heads, they offered improved exhaust ports and EGR compatibility. The later version of the book which I just generously received from a member at SpeedTalk.com, is from 1985 and features instructions for the later Aluminum heads and a revised version of the block.
Part of the lack of concise information regarding the Super Duty 4 engine and program can also be attributed to its quickly evolving development, as the Pontiac Motorsports team made consistent improvements, with lessons learned in racing. Earlier Blocks, 1027633, have 2.5SD cast into the sides, later versions, the PN stayed the same, were cast with Super Duty on the side. Both have reinforced Pan Rails, and Deck surfaces, and partially siamesed bores. The later Super Duty castings have longer sleeves which can be seen from the bottom of the block, and Pontiac made longer stroke crankshafts available during that time as well
At some point Pontiac made the switch to a 5 cam bearing cam tunnel, I assume this lines up with the entry in the GTP-Light as power and speeds would have gone up, and the race SD4 motors started using roller cam bearings. Pontiac also offered Aluminum Super Duty blocks, 10049881, in the late 1980’s. The Aluminum blocks in a revised SBC and GM Metric bellhousing were available from Nick Arias Jr. until his passing and business closure. Sometime later in the 1990s, Kansans Racing Products took possession of the Iron Block molds and continued production into the early 2000’s ( PN 10093306), but they are no longer making blocks today.
The earlier SD2.5 Blocks 10027633/10027634 where designed and sold for use with 3.25 and 3.00 stroke cranks, it’s my opinion that the 5 1/8” cylinder sleeve really hits its usable stroke limit at 3.5”, and at that point you need very long connection rods to keep the piston pins inside the engine. I don’t have any idea on the sleeve length in the later version of the blocks, but the casting does have more material at the bottom of the bore.
The Super Duty Heads started off with PN 1027775/1027776 as a revised port heads with a close net shape to the factory X-Car heads (Pre-Fiero production). This head required a lot of machine work to assemble and put into race ready trim, due to being run on Pontiac Factory tooling. I don’t believe many were made and were quickly discontinued in ‘83. Then Pontiac Released 10031322 and 10031323, for bare unmachined and a machined iron head (with EGR). This head had revised intake ports, raised floors on the exhaust ports, and required less work to install on a Super Duty block.
Pontiac Developed several aluminum heads as well. The 10038433 head appears to be an aluminum version of the 322 head (with no EGR port), with bronze valve guides and hardened seat inserts. The 10045437 head had revised and further raised and enlarged exhaust ports. The 10049801 aluminum head has repositioned and raised intake ports combined with the revised exhaust ports of the 10049437 head.
All that established, I will start with the car and engine as I purchased them. I dug through the receipts I was given, and compiled a list of parts quoted, parts sold, and how this engine was built. This year I finally pulled the block out of the car, took the iron head apart and disassembled the engine.
EDIT: Head PN's updated to correct casting numbers
[This message has been edited by FieroWannaBe (edited 12-27-2022).]
I'm surprised the "775" head was not mentioned. I had one of those on a 2.5(?) SD that I owned for a while. It was a cast iron head that used the same gaskets as the stock Duke engine. Other than that, I know very little about it. But the engine itself was quite streetable. Probably made ~200 HP, with a 6000 RPM redline. Idled at ~900 - 1000 RPM. This was a very early SD. Iron block and head. The car (an 84 Automoda conversion) was owned by at least 3 people before I ended up with it. (It had gummed up Dellorto carbs on it when I got it. I swapped the Holley on, and was going to rebuild the Dellortos. Ended up selling the whole shebang.)
[This message has been edited by Raydar (edited 12-08-2022).]
I'm surprised the "775" head was not mentioned. I had one of those on a 2.5(?) SD that I owned for a while. It was a cast iron head that used the same gaskets as the stock Duke engine. Other than that, I know very little about it. But the engine itself was quite streetable. Probably made ~200 HP, with a 6000 RPM redline. Idled at ~900 - 1000 RPM. This was a very early SD. Iron block and head.
Thats becuase I copied the wrong PN from my book. The 10027776/10027775 was the original SD4 head, which did have more in common woth the stock duke than the later heads. Ill update yhe summary above.
Originally posted by FieroWannaBe: ... The 10027776/10027775 was the original SD4 head, which did have more in common woth the stock duke than the later heads.
I didn't realize that it was the original head, but I'm not surprised. But I really enjoyed that I was able to use factory gaskets and other stuff when I was changing parts around. Just made stuff easier for someone like me who didn't really know what I was doing, as far as the SD went. I wish I hadn't had to sell the car. We were about to move, and I didn't have anywhere to store it. All I did was bolt on that Holley. Never did even the first bit of tuning. And it still ran like a striped ape.
Looks like a fun project. Since the engine seized from non-use, I would be inclined to dribble some ATF (or maybe even Kroil) into the spark plug holes, and let it sit for a few days, to see if it might free things up. Would be a shame to tear down a low mile engine, unless that was your plan, regardless.
In February of 2016 I trailered the car home, during a snow storm, which was quite an adventure. I changed the wheels to some that at least could hold air for a while so i could push it around, and the car sat while I devised a plan (over the course of 6 years)
All the documentation was gone through, and after tearing down the engine this is the list of all the parts I can identify that the car had when I bought it:
I believe that may be an extremely rare roof scoop. From what I remember about RRunners car domain, only 2 we're made for the race cars but they were not allowed by the sanctioning body to run them iirc. Car looks great! I remember missing out on bidding on that one, it wasn't far from me
I believe that may be an extremely rare roof scoop. From what I remember about RRunners car domain, only 2 we're made for the race cars but they were not allowed by the sanctioning body to run them iirc. Car looks great! I remember missing out on bidding on that one, it wasn't far from me
I probably have only seen a handful of cars with the roof scoop that had the air-cleaner bump out, it may very well be a rare piece.
It was functional on this car, however the piano hinge rusted out during disassembly. There was a 14" airfilter under the scoop, and the builder used a shortened Fiero hood prop to hold it up in the raised position, with the hinge at the rear of the scoop.
[This message has been edited by FieroWannaBe (edited 12-09-2022).]
Currently I have a pile of parts I've collected for his rebuild.
The old pistons and connecting rod just arent a sound design in my opinions and the really beat up the bores on this block. It had 5.700" rods, this made the piston's compression height very tall. The pins where very close to the bottom of the bores.
I still have to go through and clean the block up before sending it across town to the machine shop. The plan right now is too use some 6.200" connecting rods that have a 1.850" pin diameter (ex nascar parts from eBay), have the 3.25" SD4 crankshaft offset ground to 3.48". I will have the block bored enough to cleanup the worn bores. This will create a 177 cu in motor. All this requires custom pistons.
I have a brand new '801 aluminum head that I hope will use the valves, rockers and springs from the iron head.
I would like to find a new higher lift camshaft, these heads flow really well past .500 lift. The current cam is a little short compared to the race hyd tappet grinds from Isky and Lunati.
I will have fabricate a new intake to use some 48mm DCOE pattern throttle bodies I got from Amazon, where the trumpets will exit the decklid under the roof scoop. This engine will be converted to back EFI, and I will use a distributorless waste spark ignition.
The header will be replicated, but in a larger 1 7/8 primary diameter.
The car has a factory exhaust system. That needs to be replaced with a 3" system.
If you notice the pile of oil pans on the background, I am also assembling a dry sump oil system.
The engine as built in 1985 had a 3.25" stroke and 4.02" bore, 165 Cu In, or 2.7L. It had forged pistons and 5.7" forged rods from Crower. They appear to be a SBC application as they have an offset. The short rod, combined with the 9.125" deck height, and 5.125" cylinder length, bring the pin centerline to .075" above the bottom of the cylinder bore. This combination of parts was recommended at the time! this geometry would likely lead to piston rocking at the bottom of the stroke, and excess force on the skirt.
The bores do show wear from scuffing, as do the skirts.
This is the reason I am going with a set of 6.200" rods. The longer rod will place the piston pin higher in the cylinder at full stroke, which will help to prevent rocking of the piston. The least expensive option I could find for connecting rods over 6" were used nascar rods. The set of 8 I receieved are Pankl rods, 6.2" and the big end diameter (the crankshaft pin) are 1.850, This has become a popular size for race engines (IRL) and racers are using this size on SBC and other V8s to lower friction and mass.
The used connecting rods I found where $90 for a set of 8, included the wrist pins, which are DLC (casidiam) coated.
They are 6.200" long, 1.975" big end bore (for 1.850" bearings CB-1798H-1, $75 on eBay also) 0.903" wide.
The Small end is .700" wide, with a .708 Pin Diameter, these pins are common sizes in motorsports engines.
They have 3/8" rod bolts and weigh 537 grams (that's very light)
The non conventional specification will have to use custom pistons, which is hard to avoid when building a SD4, since it really should have flat top pistons without valve reliefs. This is becuase the valves have no incline unlike almost all V engines and OHC engines.
By downsizing the connecting rod crank pin diameter, I can have the crankshaft ground to a different stroke, The SD4 and Iron Duke where designed with a 2.1 crankshaft pin diameter, that leaves 0.25" inches of material to relocate the new size crank pin centerline in, accounting for .01 of material for cleanup and error, that leaves a maximum stroke of 3.48", this new combination places the piston pin .460 above the bottom of the cylinder bore.
What does this mean for my compression ratio? With the original bore and stroke the cylinder displacment was 676 cc The SD4 head gasket, 4.1 bore dia x .039 thickness = 8.44cc volume) The iron head volume was measured at 55cc I assume the engine has a 0.0 deck clearance, as this is recommended in the build manual. This engine was most likely at 11.7:1
My rebuild will likely be a 4.03" bore and 3.48" stroke (178 Cu In, 2.9L) The new cylinder Volume would be 727cc The new head I have has an advertised 67cc chamber, I will shoot or a finished size of 64cc The new pistons will probably at 0.00 deck height The stroked compression ratio will likely be at 11:1
In March of 2015 I bought a brand new, unfinished 10049801 aluminum SD4 head on ebay, shipped for $680. I'm not so sure I got a great deal, but it was cheaper than the aksing price at the time. I also think it will lighten the car up and add power. Last month I discovered there are a lot of changes made to the SD4 engine for the aluminum heads that arent talked about. Ill follow up with more details on that, and I'll show how the iron head is great compared to a production car Iron Duke head, and how racing really made the aluminum head into a serious race head.
This head has a sales description of: 10049801 — Super Duty Four High Port Special Aluminum Cylinder Head This version of Pontiac’s Super Duty four-cylinder aluminum cylinder head's are designed for maximum-effort competition engines. The intake runners and water jackets are raised .670" to improve flow. In the Special High Port casting, the two center intake ports are moved .800" closer together to straighten the path to the valves. Both heads’ rocker cover rails are raised .300", and the exhaust ports are raised .600". The valve centerlines are relocated to unshroud the valves, and the rocker stud holes are moved to match the new valve locations. The valve seats will accept 1.94–2.08" intake valves and 1.60–1.625" exhausts. The combustion chamber volume is 67cc. Technical Notes: Valve guides are supplied but not installed. A template is provided for redrilling headers to fit the revised exhaust flange bolt pattern. An intake manifold must be fabricated to fit the High Port Special's port spacing.
I am still finding the right valvetrain parts to finish this head, or I may use the existing valves/springs from the Iron head.
For the intake, I started my plan with some GSXR1300 throttle bodies, however they are only 42mm ID, which is undersized for the airflow of any SD4 head.
This year I found some knockoff DCOE pattern throttle bodies, I bought some in 48mm, which should be correct diameter for the port area with a 1 degree taper.
This also means I have to fabricate an intake. I plan to run a 3d printed CF-Nylon manifold. I did some test fitting and Have an idea on how it may fit for now. I
I am still working on the details, especially after receiving the later version of the SD4 guide.
One new nugget of information not in the often shared Super Duty guide PDF, is that pontiac had 2 different SD4 head gaskets made. GM 10031324 for the cast iron head and GM 10038952 for the aluminum heads
Both are Fel-Pro 1015 gaskets in the build manual. However They have different Fire-rings to prevent brinelling of aluminum heads.
I currently have a new 1015 head gasket.
I ordered the last 1015-1 gakset from Rockauto. We will see if the right gasket shows up, but the interchange information doesnt match up to the Fel-Pro website description.
The build manual shows a Fel Pro 1015 gasket, but illistrates the fire ring difference.
I will need to get all three gaskets together to compare, the 1015-1, the 1015, and my gasket the engine had when i took the head off.
[This message has been edited by FieroWannaBe (edited 12-15-2022).]
Wow I am very surprised you are able to find parts for this thing on RockAuto, do you have to search by part# or is there some vehicle you are able to enter that used this motor? It was never used in any production vehicle was it?
Wow I am very surprised you are able to find parts for this thing on RockAuto, do you have to search by part# or is there some vehicle you are able to enter that used this motor? It was never used in any production vehicle was it?
I had to search by GM part number and/or Fel Pro part number. They really only carry some gaskets and bearings. The Super Duty engine was never used as any production engine, but i shares 90% of its design with the Factory Duke, most bearings and gaskets should interchange with a duke, if these parts store parts are up to the stresses of higher output is the real issue. The closest production engine to a SD4 is the Vortec 3000 3.0L industrial engine. although there are many dimensional similarities, It is based on the Chevy II I4, not the Iron Duke.
I can show some of the differences in the gaskets between a production Iron Duke and the Super Duty Duke to show how different they really are.
Pretty much any part off the shelf specific to the Super Duty engine is N.O.S. I cant find most the parts listed in the build manuals save for some gaskets and bearings,
[This message has been edited by FieroWannaBe (edited 12-16-2022).]
Head Gaskets as I have them: 1015-1 - this has a larger fire ring (looks to be not steel material) and has black-ish gasket material. Marked R1 10151 1015 - This is a darker blue with a large fire ring, marked R5 1015 515SD - This is blue stripe material with a large fire ring (similar in size to my original head gasket. This is has more gasket material than the others, but all holes and bores line up. 9405 PT-1 - This has a very small fire ring completely encased by the blue stripe material. This is the factory replacement Duke gasket. 1015 - This is the head gasket my SD4 came with. It closest resembles the 515SD in construction, but is the overall size of the 9405 PT-1.
I was able to flow test the Iron head, with and without the 2BBL intake, and with a 1.5" exhuast stub attached. Done on a SF750.
The iron head would be great for a street engine with a milder than wilder camshaft, not a lazy port, and good velocity. I am looking forward to finishing the '801 head to see how much better it really is.
Just for comparison, the Quad 4 "086" head flows 269 cfm intake and 180 cfm exhaust at .410" lift and 28" H2O differential pressure. 0.410" lift is with the stock high output cams. Comp Cams can make a cam with 0.430" lift but that only adds a few cfm with this head.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
Just for comparison, the Quad 4 "086" head flows 269 cfm intake and 180 cfm exhaust at .410" lift and 28" H2O differential pressure. 0.410" lift is with the stock high output cams. Comp Cams can make a cam with 0.430" lift but that only adds a few cfm with this head.
A 4 valve head has a lot more potential for raw flow numbers, and H.O. Head was very well designed for the time. I believe the heads on my 3.4 DOHC motor are supposed to flow 261 cfm at .400 lift (I have cams reground to .396 lift.) I think the 3.4 head has a larger valve angle and lower port incline. However most 4 valve heads are over-valved, they give up velocity for flow. And 2 valve heads are under-valved, they give up flow for velocity. The trade off is mid range torque production and port energy, which can aid in ram tuning effects. There is a video clip out there on the WWW (probably a couple, one from Paul Vanderley and one from John Callies, Where the GTP-L switch from the '801 2V head to the 4 valve Cosworth head cost the team mid-range torque and hurt overall lap times because the power band became shorter and "peaky".
The Iron head has room to improve, as it has lots of material left in the port near the head bolt pinches, that could improve flow at the top end, but port volume will increase, and that may shift peak power higher. The aluminum head in comparison should be able to achieve flows near 300CFM at peak lift. These heads can support lift past .800, and cams are "available" whenever cores show up, as well as older grinds, for very high lifts and durations.
The other difference in the "duke" architecture is the displacement advantage, since this engine is already at 2.7L and this particular motor could potentially achieve 2.9L of displacement, that will move the power band to lower RPMS with the available flow, making working with the worn-out and outdated Fiero transmissions a little easier, where a little broader of a torque curve can be needed, given the available ratios, compared to a Q4 Getrag and the Q4 architecture 1.8-2.4L displacements.
I have built up a 3.4 DOHC, I'm working on a LS4 build concurrently, and this SD4 revamp, I'm not favoring one technology over another, but just having fun trying to pull out some performance from different platforms and learning some stuff along the way.
[This message has been edited by FieroWannaBe (edited 12-28-2022).]
Great info. I'm not trying to rain on the Super Duty rebuild parade and will follow this project closely for tips on exracting performance from a 4 cylinder. I am contemplating stroking a 2.3L Quad 4 with a Twn Cam crank. With an overbore that gets the displacement to around 2.6L.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
To add fuel to the fire: An un-ported K20 head will flow 295CFM at .400 lift, and over 300CFM at .500. Ported and re-valved Kawasaki GSXR heads have surpassed 300CFM at .500 lift, and that is on a small 3.2" bore. Ported LS3 or Gen II Hemi heads can approach 370 CFM over .600 lift
The head flow is one factor (a big one) in the engines ability to make power, more flow, more power.
Modern heads are better, bigger, and have great ECUs to make things work in almost all conditions, and some high tech roller cam designs, with wide LSAs to keep things behaved for day to day driving. This engine isn't going to be one of them.
In order to predict where in the RPM band the peak torque, and subsequent power, will be made we need to factor in displacement, port velocity (energy), cam shaft timing, and how ram tuning affects it all. Big flowing heads by their nature have big ports, big ports require large volumes of air to start making the ram tuning effective, via a higher velocity of air. This means any motor will make more power in higher RPMS with bigger ports compared to smaller ports which will reach peak velocities at a lower airflow, and choke at high RPMs, limited top end power.
As I piece my engine together I am trying to pay close attention to all the factors I can control to enhance power in the range I think best suits the application, A street motor with some time spent on a race track turning laps. I want an engine with a broad torque curve that can breath well at the upper RPM band. There will still be a 4 speed behind this, so it will have some hefty splits at each shift, so a peaky motor isn't ideal, and exceeding 7000 RPM will make the shifts much harder to accomplish with the sluggish synchro's.
The Iron head has a 180cc intake port, for the time it was released, this in on the higher end for it's bore, but not exceedingly large, this is the size port a lot of hot 350s have, and much larger than most factory ports, especially in the 1980s. The aluminum heads as cast have a port of 178cc, and will only become larger as the bowls and throats' of the port are finished, so I don't plan on porting it any larger than necessary to achieve to flow needed for my power-band goals even though it has lots of room to grow.
Originally posted by FieroWannaBe: There is a video clip out there on the WWW (probably a couple, one from Paul Vanderley and one from John Callies, Where the GTP-L switch from the '801 2V head to the 4 valve Cosworth head cost the team mid-range torque and hurt overall lap times because the power band became shorter and "peaky".
Interesting and certainly matches my experience with the Quad 4. Great from 4000 rpm to 7000 rpm. 2000 to 4000 rpm needs improvement. A reason I think that going from a 85 mm to 94 mm stroke with the Twin Can crank will bring more overall performance than one might expect from the displacement increase.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
Because my car was an 84, it had a V-belt accessory drive, Pontiac did not have a harmonic damper on the Iron duke at this time, and the owner did not have the Super duty balancer installed.
I did find hunting through rock auto and google image search, that a mid 60's-70's Chevy 250CI I6 balancer, looks very similar the Super Duty Balancer. The bore measured out to the needed 1.248. https://www.rockauto.com/en...12&jsn=1&jsn=1&jsn=1 This balancer has what looks like a correct spacing for the V belts, This is for a 1967 Chevy C10, w/o AC, and not HD cooling. It even came in with a nice Black Oxide finish. It will need a new TDC mark added so it can be used with the Duke Pointer.
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