The Pontiac Super Duty 6 (SD6) - and the GT1 Fiero (Page 1/1)
Craig71188 DEC 22, 10:41 AM
In the process of restoring / resurrecting our tube frame GT1 Fiero, I was searching for spare 90 degree V6 parts when I was contacted by gentleman in Canada that had two engines built by Spice Engineering. A deal was struck and I recently went and repatriated them the the U.S. The engines came with several folders of documentation, so I thought I would share a little info on the non-Huffaker Fiero's. As most know, the tube fram Huffaker cars had a transverse mounted SD4 and used the stock transmission case with straight cut gears / dog rings from Webster. While Spice is better known for their GTP cars, they also built a few Fiero's with a longitudinally mounted SD4 and a Hewland DGB gearbox. I know of two of these, but no idea how many were actually ever built. At one point, these cars were fitted with a 4.5L 90 degree V6. The engines I have are numbered PMS-007 & PMS-008 and are referred to on Spice's manifest as "SD6". Also included in the paperwork are copies of the "Pontiac Winners Circle" newsletter from the late '80's, here too, the 90 degree V6 is referred to as the "SD6".



Currently the motors are set up for SCCA GT1 with carburetors, but included with them is a Kinsler V6 fuel injection system (also cast as Pontiac & SD). Interestingly, the injection pump is numbered "PMS-005". The one oddity is that these were built as even-fire motors, while virtually all the later V6's were built as odd fire with common pin cranks. These engines are fitted with Crower manufactured crankshafts (part # referenced in some vintage GM Performance catalog pages), Cosworth rods & pistons and Brodix-Pontiac Heads & Intakes. The engined are also fitted with a fixed distributor body (no advance/pickup - only used for spark distribution) that are fired by a crank trigger on the rear of the crankshaft and utilize an MSD timing box for advance / retard along with an MSD6-AL ignition box. Dry sump oiling along with some external plumbing for pressure and scavenge of the block. Camshafts are roller lifter and utilize Jesel shaft mounted rockers with specific offsets for clear the larger ports/relocated pushrods.



Dyno sheets indicate in their current trim, thy make approx. 460-475 hp at 7400 - 7700 rpm. Redline seems to be 8000 rpm.

I figured I would share a little information here for posterity. The car itself was built in Florida by a gentleman named John Gunn. John raced in IMSA (built two of his own GTP cars) and also in Can-Am. In an odd twist, his shop operation was "Phoenix Racing". This car has no IMSA history, it was only raced 4-5 time in SCCA events over 20 years ago then was stored (somewhat poorly). Current plans are to get it up and running for SCCA Time Trials and Gridlife events.
2.5 DEC 22, 10:45 AM
Cool stuff!
Raydar DEC 22, 12:52 PM
Interesting! I'm curious, though.
Are these Pontiac-derived blocks/engines? Or are they basically 4.3 Chevy engines? Or a hybrid of both? (I've seen some other Chevy-hybrid stuff with Pontiac castings.)
What does the tranny bolt pattern look like? SBC or GM Metric? Or something else?

R Runner might be able to contribute some info. His tube frame car is a longitudinal setup with a VanDerLay-built SBC. Looks to be a similar setup to what you are showing. (Aside from the fact that his is, I believe, largely home-made.)

[This message has been edited by Raydar (edited 12-22-2021).]

Craig71188 DEC 22, 01:30 PM

quote
Originally posted by Raydar:

Interesting! I'm curious, though.
Are these Pontiac-derived blocks/engines? Or are they basically 4.3 Chevy engines? Or a hybrid of both? (I've seen some other Chevy-hybrid stuff with Pontiac castings.)
What does the tranny bolt pattern look like? SBC or GM Metric? Or something else?




Engine is basically a beefed up 4.3L. 4.3L architecture/tranny bolt pattern. Pontiac badging on Brodix cast heads that differed slightly from the Chevy heads. Blocks & bottom end components are the same - just top end badging and some minor variation for corporate promotion. Basically 4 styles of heads as listed below in order of lower HP to highest HP potential. Various casting numbers in some of the offerings, but basically they fall into these categories.

23 degree valve "low port" - Chevrolet only, works with street 4.3 intake
23 degree valve "raised port" - Chevrolet & Pontiac versions, requires specific intake manifold
18 degree valve "raised port" - Chevrolet & Pontiac versions, requires specific intake manifold
Splayed Valve head - Chevrolet Only - unique intake / exhaust / valve cover
RWDPLZ DEC 22, 07:52 PM
Thanks for sharing, fascinating stuff!