SD4

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SD4

Postby mxart42 » Tue Aug 08, 2017 3:06 pm

Hi everyone,

Long time lurker, first time poster here. I’ve been through all the 2.5 posts on the forum, and hope someone with SD4 experience could weigh in. What’s your thoughts on the engine? Taking cost out of the equation, would you consider the SD4 a viable replacement for the Iron Duke and usable on the street?

I have an 80 Spyder I’m about to have professionally restored. It has the crossflow Iron Duke, which I'm investigating swapping out for a mild, low-compression SD4. The car would be primarily used for weekend driving.

I realize this isn't the most cost-effective transplant, but I’d want to keep the car as close to the appearance of stock as possible and retain all the accessories (particularly the a/c). My hope is that the SD4 could be a drop-in replacement. My days of wrench twisting are long behind me, so the job of rebuilding and fitting would be the responsibility of the restoration shop.

Having said all that, I’m looking for a little feedback on feasibility. Here’s what I’m looking to accomplish:

    -150-200HP
    -Runs on 93 octane pump gas
    -Has a smooth idle
    -Allows me to keep my stock equipment
    -Fits under the hood without requiring a hood scoop
    -Has good reliability and longevity

Is this doable? Right now, this is all just a fact-finding mission for me. This is not my area of expertise, and for all I know, may be completely out of the realm of possibility. I understand SD4 parts are few and far between. So here’s one last question: I know if I decide to rebuild the Iron Duke, anything beyond 120hp is not going to be possible due to block and crank issues. Is it possible to use an SD4 block and crank with the Iron Duke top half?

Thanks for indulging me.
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Re: SD4

Postby HI WINDING MONZA » Tue Aug 08, 2017 8:55 pm

I'll try answer your questions in a few days...,...all I can say now is the performance stuff for Iron Dukes is pretty much dried up. And SD4 's are very rare to even find and real expensive if you do find one. No parts interchange between them.

I've owned , street raced, and drag raced Iron Dukes for about 30 years with the same stock block my car came with brand new. I got about 144 HP at 5800 with a mild build seeing 7200 rpm at multiple times with no problems.

Doug in P.R, 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
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Re: SD4

Postby cammerjeff » Wed Aug 09, 2017 1:02 pm

I agree with Doug, The SD Iron Duke is a Great engine, but very expensive, and as for as I know only shares the name with the Street version of the 2.5 Iron Duke.

It would make a great swap into an H-body, I would love to have seen one done, but realisticly you are looking at over $10,000 for a SD4 and that is not counding al the little things that would need done to the chassis to make it work.
Jeff R

78 Sunbird Safari Wagon, 3.8 N/A, 1971 Catalina Freeway Enforcer
77 Astre Formula, some day soon powered by a 215 Buick V-8
1973 4-speed Lemans Safari STOCK!!!!! 1978 Catalina Safari
1971 Lemans Safari/GTO Clone, 1969 Firebird Sprint 301 ci OHC6, T-5, 4.10 12 bolt posi
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Re: SD4

Postby Greybeard » Wed Aug 09, 2017 3:20 pm

I used to race a hydro with a Chevy ll four. The engine came out in 1962, and a 3 ltr version is still used by Mercruiser today. Thousands of these 180cid engines are lying about in and around boat repair shops. Aftermarket intake manifolds, cams, dress up parts, maybe still a header or two are available. They have a chevy bellhousing bolt pattern. Engine parts are cheep enough because the architecture is the same as the Chevy 6. The link below is to a guy who builds 6s, and has parts for the 4cylinder.
Good luck

http://www.12bolt.com/
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Re: SD4

Postby Monza Harry » Wed Aug 09, 2017 11:31 pm

Greybeard wrote:I used to race a hydro with a Chevy ll four. The engine came out in 1962, and a 3 ltr version is still used by Mercruiser today. Thousands of these 180cid engines are lying about in and around boat repair shops. Aftermarket intake manifolds, cams, dress up parts, maybe still a header or two are available. They have a chevy bellhousing bolt pattern. Engine parts are cheep enough because the architecture is the same as the Chevy 6. The link below is to a guy who builds 6s, and has parts for the 4cylinder.
Good luck

http://www.12bolt.com/

I would like to add that some of the architecture is also compatible with SBC like roller liters and rockers, pistons with the right pin height or a corrected rod length. When My Dad (with us as kids) ran that same engine (Chevy II) in our "Midget Race Car" we used the OHC Pontiac rods with HiPO 283 pistons with a "Hair-cut" on the domes and the aforementioned Marine head and with some work, approximately 13:1 compression can be had [Alky and Hilborn injection]. Here is link with some points of interest in the "Racing" section: https://en.wikipedia.org/wiki/Iron_Duke_engine, as in still available! But it does sound expensive! If I was going to swap a I4 in it would likely be an "EcoTec" the biggest one with the blower! 300HP, [SAE Net] FI, light weight aluminum, and proven. with a few mods your car will run like it is "Possessed"! All while knocking down near 40MPG highway. It should also posses even better balance and therefore handling. Harry
I'm not a hoarder I'm a preservationist 78 Monza Spyder (Soon To Be 2+2 with Spoilers)
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Re: SD4

Postby mxart42 » Thu Aug 10, 2017 2:28 am

I would have been ok with $10K if I knew the engine was going to meet my requirements, but the prices I came across were a bit higher than that, and no one could answer any of the questions I was asking.

I originally reached out to Doug Thompson at Kansas Racing Products, and was quoted $15K for a turnkey engine. He also told me his builds weren’t designed for street use. He couldn’t tell me anything about the fit, but said his engines used US-standard tap sizes all around and thought the Iron Duke used metric.

After that, I tried Nick Arias Jr. but they said they weren’t doing full engines any longer and were only selling blocks, though they did have one complete SD4 for sale somewhere north of $20K (though again, not designed for the street).

I tabled the idea until I saw an SD4 popup on Craigslist (hat tip to MonzaAddict). According to the seller, it needed rings and reassembly, but was in good shape. I was all ready to pull the trigger when it occurred to me that I had no idea what I was potentially getting into, e.g. parts availability, would it fit under the hood, etc. I figured I’d ask the group before I started throwing money at a maybe.

I wouldn’t even be entertaining this idea if I could’ve found an 80 in perfect shape with the V6, but it took me close to a decade to find the one that I did. I’m only jumping through these hoops because my 80 is a rust-free original that I’m trying to keep as close to stock (or at least the look of stock) as possible.
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Re: SD4

Postby monzaaddict » Thu Aug 10, 2017 3:18 am

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Re: SD4

Postby cammerjeff » Thu Aug 10, 2017 8:36 am

That could be a fantastic deal, but is probably on the other side of the country from him.
Jeff R

78 Sunbird Safari Wagon, 3.8 N/A, 1971 Catalina Freeway Enforcer
77 Astre Formula, some day soon powered by a 215 Buick V-8
1973 4-speed Lemans Safari STOCK!!!!! 1978 Catalina Safari
1971 Lemans Safari/GTO Clone, 1969 Firebird Sprint 301 ci OHC6, T-5, 4.10 12 bolt posi
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Re: SD4

Postby Monza Harry » Thu Aug 10, 2017 9:40 am

Too Bad about Arias as they used to make the complete foundation for an all aluminum ChevyII [used a SBC head IIRC maybe Dick or Greybeard remember better than I] for the midget race cars. that would more or less be right at home in the engine bay of your Monza. The Iron Duke was an evolution of the ChevyII not a smooth one as not much actually swaps over but much does "look" similar. Harry
I'm not a hoarder I'm a preservationist 78 Monza Spyder (Soon To Be 2+2 with Spoilers)
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Re: SD4

Postby HI WINDING MONZA » Thu Aug 10, 2017 5:34 pm

There was an outfit in the 90's that would redrill a 2.5 Iron Duke to put on a SBC head. Seen one on a rail go 8's at a track in NY.
I'll post what I did to mine this weekend .

Doug in P.R. 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Re: SD4

Postby Fastmax32168 » Fri Aug 11, 2017 5:20 pm

OK I gotta ask,
Why an SD4 at such expense and difficulty when there are so many better and less expensive options for the car?
A curious mind wants to know.....
Roy
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Re: SD4

Postby HI WINDING MONZA » Sat Aug 12, 2017 6:43 am

Ok here we go.... The bases of what I did with my stock 151 that came in my Monza with after about 70 k miles on it.

Cylinder Head: Port and polish , Clifford valve springs , Crane rocker Kool nuts ( to keep the rockers from loosing up)

Push Rods : Crane hardened ( because stock ones like to bend)

Cam: Clifford's biggest Hydraulic ( .543 lift is all I remember about it)

Intake: Stock ported with also the the base hogged out ( two holes made into one including the. EGR plate.)

Carb : Stock Varajet.

Rods :Shot peened and beam polished ,, ARP rod bolts.

Pistons: Stock, stock rings.

Lifters: Crane anti pump up

Bearings : Clevite trimetal

Oil pump :Shimed stock spring to give 70 PSI

Exhaust: Ported stock. manifold, cat delete pipe , Flowtech Raptor muffler.

Ignition: Accel coil and module, advance curve kit.Bosch platinum plugs , true real wire plug wires.

Air Cleaner: Open element using the stock base cut down with a new top.

Clutch: Ram Thunderbolt pressure plate, AMC Eagle with a 2.5 Disc ( 5 spring )

Fuel pump : electric frame mounted

That's basicly it in parts, started in the high 19's stock down to low 16's with more gear ( 4:56's ), race gas and a CJ5 Jeep 2.5 Header later on.
Never tried a head with larger valves I had gotten later on or Crane Gold roller rockers that came out . Had problems with the main beàrings ( 2 cranks wiped out) till I boosted the oil pressure. The last time I had to put a crank in the motor it lasted over ten more years.
I had problems with the Oil pump drive gear wearing out, and put in a bronze one.That wore out faster so l went back to stock. I also used a 79 head to eliminate the A.I.R. fittings on the 80 head. Stay away from 81 and up Duke engines , all of them are weak including the blocks.

I let the car sit after I moved to Arizona , Bryan came to buy his Roadhawk and got me motivated to race again so back to the track it went . But it had sat too long in the heat and a wrist pin froze up and that was the end of my Iron Duke days . Just didn't like the heat racing anyways so I put in the Caddy motor and the auto. Gave all my Duke parts by mail to a member here.

Doug in P.R. 8)
My Old Cadillac Powered Monza Still Lives...........now on its 5th owner!..........Somewhere ?

The 90's just keep rollin' along........
1990 Chevrolet Silverado Regular Cab Long Bed 350 TBI V8 700R4 105k miles
1992 Pontiac Sunbird Coupe 2.0 OHC MPFI I4 TH125C 143k miles
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Re: SD4

Postby mxart42 » Tue Aug 15, 2017 1:04 pm

Wow, thank you Doug. Much appreciated. This is great. You’ve given me a lot to think about.

I’ve been in full-on research mode since I first posted, trying to find anyone who had the same crazy idea as me but who also actually attempted it. I came across my exact scenario in a Fiero forum. The poster successfully completed the swap in an ’84.

Suffice to say, it’s not quite the drop-in I was hoping for, though at certain points it gives the appearance of being so. It was pretty much the scene in Kill Bill where The Bride was trying to kill O-Ren Ishii:

“You didn't think it was gonna be that easy, did you?”
“You know, for a second there, yeah, I kinda did.”

http://www.fiero.nl/forum/Forum2/HTML/133921.html

I’ve got a call out to a local engine shop to see if any of the issues the poster listed would be showstoppers for them.
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