Editing Pontiac V8 engine (section)

==Experimental V8s==
===427 Hemi SOHC===
This was a project started with the end goal of building a 427 Hemi.<ref>{{Cite web|url=https://tamrazs.wordpress.com/2014/01/08/pontiac-experimental-v8-427-hemi-tohc/|title=Private Site|website=tamrazs.wordpress.com}}</ref> Pontiac asked Mopar (Chrysler, Dodge, Plymouth) for help in designing it and making it work. Surprisingly, Mopar actually agreed and sent over several of the engineers that designed both the 392 and 426 Hemi. The goal of making a Pontiac Hemi succeeded but the engine was never produced.

==== Features ====
* Thin-wall, cast aluminum block
* {{cvt|4.342|x|3+3/4|in|mm|1|adj=on}} bore x stroke, 8 cylinders, each having a bore of 4.342 inch and a stroke of 3.75 inch, results in a displacement of 444.21 cubic inches (7,279.34 cc); for the Pontiac OHC 427 Hemi refers to it as a "TOHC" and lists the bore at 4.257 inch—which, with a stroke of 3.75 inch, results in a displacement of very slightly more than 426.99 cubic inches (very slightly more than 6997.124 cc).<ref>{{Cite web|url=http://www.wallaceracing.com/hemi-1.html|title=Pontiac Hemi-Head Story - Wallace Racing|website=www.wallaceracing.com}}</ref>
* {{cvt|3|in|mm|1|adj=on}} main bearings
* Forged steel {{cvt|6.625|in|mm|adj=on}} rods (Ram Air V style)
* 12:1 compression
* Mechanical Port Fuel Injection
* Large-valve heads (valve diameter): {{cvt|2.4|in|mm|adj=on}} intake, {{cvt|2|in|mm|adj=on}} exhaust
* Small-valve high-RPM head (valve diameter) {{cvt|2.19|in|mm|adj=on}} intake, {{cvt|2|in|mm|adj=on}} exhaust
* Splayed main caps, head bolts tie into main caps. Head bolts do not pull on the cylinder wall causing distortion.
* Cam drive: [[fiberglass]] belt
* Maximum RPM (high-RPM engine): over 8000&nbsp;rpm {{citation needed|date=March 2018}}
*Engine weight: estimated {{cvt|550|lb|kg|0}} complete
==== Dimensions ====
* width {{cvt|32|in|mm|adj=on}},
* length {{cvt|32|in|mm|adj=on}}
* height {{cvt|24.6|in|mm|adj=on}}
* Power: estimated {{cvt|640|hp|0}} at 7500&nbsp;rpm

===Pontiac SOHC 421CID V8===
Most likely prompted by its development of the Pontiac OHC six, the GM division built three different experimental SOHC 421 CID V8 engines in the early 1960s. According to the engineers who worked on the project, the SOHC 421 engines produced around 625&nbsp;hp and were capable of turning 7,000&nbsp;rpm.

One version of the engine featured camshafts driven off the front of the engine, another design had the cams driven by gears off the back of the engine. Apparently at least one of these engines survives under the hood of an engineer's personal Pontiac.
<ref>{{cite web | url=https://www.macsmotorcitygarage.com/mckellars-masterpiece-the-pontiac-overhead-cam-421-v8/ | title=McKellar's Masterpiece: The Pontiac Overhead Cam 421 V8 | date=10 March 2022 }}</ref>