coworker was talking about a car he had "back in the day"

didn't know the specifics of what the mods were but kindda generalized it


1978 trans am 6.6l engine, 4spd manual

mods:
alum hi rise manifold with manual 4bbl carb
hi lift cam
headers and dual exhaust (no cats)

assuming he started at 225...so he says...and the cam was a decent one...say 230 deg...stock heads...

i estimated 300-325hp and a crap load of torque...

he insistes it was near 400hp. i think that is a bit hopefull with stock smog heads.

wha chu guyz tink??

 

Stock '78 T/A - with the Pontiac TA66 motor, mind you ! was rated at 220 HP , IIRC.


W/ the 6.6L (403 , or possibly in '78 the lower powered Pontiac 400 option that was available in '77 ) the 185 for the Olds 403 , and 180(?) for the 400.

Here http://www.78ta.com/specs.htm are some specs - at the lower right is a click here which will bring you more details.

Given a 8.1 compression ratio best case, and an estimated 30% increase in HP for the mods, I'd say about 290 HP.





Whaddya think ?




Britt

 

yeah...i figured it would have low compression. and probably pretty bad heads for smog reasons.

thanks for the info...any other estimates

 

I owned a few of the 75-78 400 T/As when they were new and modded them pretty much the way you described and even with a good carb and cam the compression was what killed performance on those motors, most couldent muster 8.0 to 1 unless you cut .020 off the heads actual compression on them was closer to 7-7.5 to 1 limiting the HP you could get.. I would seriously doubt any more than 250 rwhp would be developed with a cam/carb/intake swap although the 400s were good for monster torque, which made the T/A seem more powerfull than it actually was .. most would run in the 15 sec area stock w/ auto trans while some stick cars could run high 14s, fastest I ever had one with above mods was 13.68 @ 101.77 400 auto 3.42 gear..

 

thanks for the first hand info...

there were 2 engines avaialble in the 400....7.x compression and 8.1

but even with the higher compression....it still sucks

 

for the 400, the higher compression is all from the heads, the auto was 180hp and the 4spd manual was 190hp

I used to have a 77 firebird formula 400/4spd

 

Ironically, it had an aftermarket cam , and an aftermarket intake manifold.

The shaker sat lower because of it, and low end torque sucked - you could not ease off the clutch w/o it stalling unless you gave it gas.


On the plus side, the guy had an idea ahead of it's time - he had made t-top shades for the car that matched the color of the headliner.


I miss my 403 powered 10TH Ann - and it's simplicity. But, the SS has way more power than that poor old car ever dreamed of , so I guess it's all good.




Britt

 

My fiances mom had a 78 TA with the cheaper 4 barrel 400 or 6.6 litre whatever it was, doesnt believe me that my TA is faster.......I dont say a thing

 

um...thanks NEWBIE...that was...helpful