Quote:
Originally Posted by oldskool
Talkin about all the Stock rules changes back in the early '70's, on another thread, reminded me of all the different classes Truman Fields ran, in '68 Birds.
I have pics of his Birds running A, B, C, & D-Stock, as well as B/PS. He set records in several classes. Don't know how many different records he set with his Birds. He raced '68 Birds for a lot of years.
As I've probably mentioned a few times, he was my 1st Pontiac hero !
I'll sort out some pics of his Birds running different classes, & post 'em when I have time.
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Well here's another Poser for a Pontiac Guy again:
Recall the other thread, we just went over the NHRA Factors:
385hp RA2
380hp RA4
Not what I would've guessed: It would seem the RA4 would make more power:
* New heads - better intake port or so I read
* Aluminum intake - you'd think better than iron but I've read both
* Rockers - same cam but 1.65 RR vs the RA2's 1.50 RR
For me, that Gonkulates the RA4 to make 20-25hp more than the RA2.
And yet, NHRA factored the RA4 at 5hp LESS than the RA2.
Did they really run that way (ie about the same)?
The fastest RA2 car I have from back then is Fields
119.52mph record, RA2 4spd Firebird, June 1971
Compared to the fastest RA4 car
114.79mph record, RA4 auto GTO, Nemesis, May 1970
Of course you then have to correct the GTO for its weight (200 lb ~ 2mph) and being an auto trans (trap speeds about 2mph lower)
So make it 118.79mph for what we've converted to a "68 Firebird 4spd RA4". A more accurate conversion gives 118.95mph.
So
119.52mph best RA2
118.95mph best RA4
Given how sparse that old data is, I'd call that "the same", which jives with NHRA factoring the RA2=385 and RA4=380, ie "the same".
I looked in my modern NHRA class files, a couple years old.
For stock class
RA2=335-340, RA4=345 in the Firebird
RA2=365, RA4=365 in the GTO
So, within the strangeness of modern factoring, the RA2 and RA4 are still factored "about the same". It's more a function of the body than the engine.
I wondered, what is your feeling over the years, are the RA2 & RA4 about the same power or is one stronger (in the same weight car!)?