Dyno's, Setting the Record Straight

[Joe Rutledge]

Scott has his history absolutely correct on the Trans am racing.

I don't think it ever could be claimed that the Boss 302 destroyed the Z-28's in 1969. The two were about on parity, with significantly different RPM ranges for their torque & HP. The Boss 302 was revving way higher as mentioned before in one of the posts. It's mid-range was so-so, but when you were pulling 8500rpm it did get different. That's why Ford marketed special racing titianium valves and "9,000 rpm" rods, which were available over the counter thru Muscle Parts. Perhaps the Boss started the season with more power, but Penske via Traco engines probably had something to say about that as the season wore on. For those who weren't following what went on back then, Ford won the first bunch of races just as much on antics as on power - Parnelli and George Follmer played "Dodge-um" cars with "Captain Nice" (Mark Donehue), with the grinding, bumping and banging being VERY severe. But Mark and Penske got the last laugh by beating George and Parnelli at their own game and Chevy took the title. The title was decided less by who had more horsepower, than who drove well and survived the demolition derby (early on things like Parnelli passing Mark, and then slamming on the brakes forcing Mark to bash into things was common - fun to watch or read about if you were a Ford fan, but in retrospect, maybe a bit rough and unsportsmanlike). And as Scott says, the Boss barely "squeaked by" AMC of all things the next year.

On the subject of the 302, it probably made more top end power than the Z. But narrow band top end power alone does not really make an engine "more powerful". This was during Ford's dubious era of huge intake ports with crappy exhaust ports. The fact was the Boss 302 was lacking in mid-range HP and torque relative to its competion, let alone on the street. I don't remember my friends Boss being too bad, certainly just has fast or faster as another friends 66 GT-350 (on the street), but I do remember the then "enemy's" Z's being just as fast overall (everybody on the street disconnected the rev limiter, as did many of the magazine tests). And frankly there were just as many or more "good running" Z-28's than "good running" Boss 302's. Doesn't mean I don't love the Boss or think it and the Boss 429 were two of the hairiest looking and well executed Mustangs ever made.
When you moved the 302 boss head to the 351 (becoming a 351 Cleveland-4V), things got much better because of more cubic inches for the intake port/valve. But don't forget the 302/351 was ultimately handicapped by exhaust problems noted above, which caused Ford pro-stock racers to devise all sorts of "correction" programs to fix the head, like lopping off the entire exhaust section of the head, and "bolting" on "high port" exhaust plates (about an inch thick) to fix it. The 351 did not win in Pro-Stock until this mod was done. Later on, hi port heads became available which fixed the problem. The Boss 302 kind of had the reverse problem of the Boss 429 in this area. If I remember correctly, the Boss 429 exhaust port was OK, but the intake port huge or not was bad because it was designed to go under the Torino Talledaga hoodline for NASCAR. Probably a classic case of both designing a port based on hoodline and expected NASCAR RPM range. Which is probably why it was deficient for drag racing and the street in general. Towards the tail end of Big block pro-stock in the early 70's, Gapp & Rausch were "cutting and pasting" the top end of the 429 intake port trying to make it better so they could attempt to come close to the SOHC in power output. They got close, but never really did make it, the Pro stock rules changed making small blocks the only way to go and so on.

Joe