So just curious here have any Buick fans built a Buick rainier the v8 models are ls based. I have a 2004 rainier with a 11.5:1 5.7 ls with my own ported heads and a daily drivable 220* 0.600 lift cam. About to go bigger on the cam and cylinder head. Im a professional engine builder and efi tuner, but also a huge Buick performance nut. In my opinion this is the last Buick built with real performance potential “rear wheel drive”. My end goal for my car is to build a boosted 427 cid for it, I’ve had to develop my own parts and solutions to some of the challenges of this platform so just trying seeing if their is a market for this thing among Buick enthusiasts. I suspect like the Chevy ssr and trailblazer ss the market is probably small but would like to help anybody trying to build a fast 21st century Buick.
I’m rebuilding mine right now but nothing crazy, just a fresh 4L65E trans and a sloppy stage 2 5.3 with valvesprings and a few other upgrades. I was going to drop in my modified 6.0 however I wanted to keep this one decent on fuel as all of my vehicles are pigs on fuel lol.
So I’m 5.7 liters and gets 24 mpg cruising at 80. EPA fuel economy was rated at I believe 15mpg. Like any big engine if I’m hammering on the thing it gets 10 to 12 mpg. I messed around with awd for a while but kept breaking front axle shafts and diffs and then gave up on it. With the 4 link rear suppension awd isn’t worth the traction on until making some serious power 800+ .although I’ve got all the parts to go back to awd in the future. Even with I mild cam 5.7 rainier I’ve been able to put three car lengths on a 2020 5.0 mustang. The rainiers are light for what they are mine weighed 4600lbs on the scales lighter then a bmw x5m of Jeep srt8. Theirs a lot to be had here in this platform and I hope more buick nuts climb on board
what do the competitors weigh? it’s funny because my 75 Regal is 3250 pounds but people think it’s a heavy beast vs their 7000 pound truck lol. Yes my suv is setup for AWD still but I’m not running the front driveshaft. It’s a unique setup as you still get 100% rear wheel power without removing the t case. The TBSS need to be physically converted back to RWD as the t case is different. I agree, a modified engine, headers, and custom tune can get much better power and mileage vs stock. If you are running the AWD oil pan then consider adding a baffle for oil slosh control.
So for example a bmw x5m is 5400lbs A jeep srt8 is 5200lbs And the highest top speed suv the Bentley bentayga is 5800 lbs. so a 4600lb Buick rainier is most likely the lightest of the bunch I hear a lot of opions about how unibody cars are lighter the full frame cars but like a 69 Dodge Charger vs a 70 Buick gran sport the scale tells a different story also yes the rainier has a electronically controlled clutch plate style transfer case and so if you pull the front drive shaft or the actuator it will be 100% rwd the TBss was a helical Torsen center differential that is like a true trac but with a lot more torque vectoring ability. As for the oil slosh issue I made my own oil baffle that was welded into the pan it works perfectly I made my own because a can tig weld and can or I would have bought one. Also in terms of fuel economy no matter what engine your running if you reduce Bsfc at crushing speed fuel millage will increase by the percent change in brake specific fuel consumption. Unless you change the vehicles aero dynamic drag or vehical weight. one cool fact about the rainier the project lead engineer was Tom Wallace he worked at Buick since the 60s played a big roll in the Buick gs development he also was on the grand national development after the rainier he because head engineer of corvette.
Cool info! Mine has a 4 corner suspension drop with spacers to fine tune the ride height. I think it’s set at 1.5” drop now but it really helps the ride quality and the cornering is improved. The kit came with shocks and springs. I agree these are awesome vehicles.
