I have a 98 Fbird with the series 2 engine and spec wise it looks exactly like the ‘86 Turbo Regal except 10:1 compression. To be honest I’d think they were under-rating the HP except that the time numbers back up 235 HP.
Here’s the thing: Abbot Racing Heads have a 98 Fbird daily driver that they measured at the rear wheels @273 HP. N/A, No intake to speak of. Their own Stage 2 heads. A Comp cam for which they gave the specs mid-high 400s) and long tube headers. That’s it. That must be near 300 HP at the crank.
Buick were seriously choking that engine down or something because it isn’t hard at all to get those humble 231 cubes to stand and deliver
In fact some chick and her dad got 600HP out of a V6 Fbird using a home made double turbo setup.
I’d be willing to bet that any of those Regals still around are 300HP or better now. Some of them that pass me on the highway sound down right NASTY.
The SII is a great motor compared to the 3.8L in the 86-87. The Heads on the 86-87 were barely a step up from the Heads Jeep sold back to Buick in the 1970’s. The ‘89 TTA heads were even a huge step up from the 86-87 heads. Turbocharging/intercooling made all the difference. SII heads start off on a whole other level.
If Buick stuck with RWD and turbocharging, by ‘96-97 they would have had a legit Corvette killing, 380-400 HP V6 on 93 octane. I’m sure one of the reasons they supercharged the FWD cars instead of Turbocharging was the carnage that would have come from Front Wheel drive cars running 125mph in the 1/4 mile with only race gas and mild tweaks.
Before I ported the heads/cammed my ‘86, it ran mid 11’s @ 118 in the 1/4 mile but couldn’t rev above 5,200 RPM, because the heads were so terrible.