Cadillac History

[90Brougham350]

Oh my, that's one hell of a gorgeous Cadillac! That belt line is simply stunning. That's the Standard of the World!

[gdwriter]

I love these Eldos for their audacity. Saw one in Orange County, CA on eBay a few weeks ago with a starting bid of $100K. Don't think it sold, though.

[ben72227]

Today is Tuesday (December 13, 2005) and we are doing a feature on a group of Cadillac engines today. I know, I know, probably not as interesting as a car model, BUT we have to cover everything in this history class

This weeks topic is none other than....

THE OHV V8s of the 80s! Yay!

HT-4100
Another new V8 appeared in 1982 as the HT-4100 (option code LT8). This engine was originally designed for transverse front wheel drive use in the planned downsized 1983 Cadillac sedans. However, delays in General Motors' BOC (Buick-Oldsmobile-Cadillac) large sedan program and the colossal failure of the L62 V8-6-4 caused the HT-4100 to be rushed into production for the 1982 model year.
The 4.1 L HT-4100 featured an unusual aluminum block with iron head construction. Bore was 88 mm and stroke was 84 mm; in most applications, it was equipped with throttle-body "digital" fuel injection. Initial output was a paltry 125 hp (93 kW), not nearly enough to provide Cadillac-level acceleration in the heavy Cadillacs of the early 80s (which were designed for a much bigger V8); early models were plagued with reliability problems. Later versions of the HT-4100 were used in the originally-planned front wheel drive configuration throughout the Cadillac line (with the exception of the limousines and the Cimarron).
The version found in the 1987 Cadillac Allante featured port fuel injection, with output of 170 hp (126.8 kW) and 235 ft.lbf (319 Nm) of torque. The 4.1 was superseded by larger models and ceased production in 1988.

HT-4500
Engineering allowed the company to begin to raise displacement and output again. A bored-out (to 92 mm) 4.5 L HT-4500 version was introduced in 1988 with 155 hp (116 kW). Various versions were built between this introduction and the end of production for this engine in 1992, including a high-output LW2 with multiport fuel injection version for the Allante which produced 200 hp (149 kW) and 270 ft.lbf (366 Nm).

HT-4900
An even larger version, the L26 HT-4900, debuted in 1991 at 4.9 L with a square 92 mm bore and stroke. Power was the same as the 4500 at 200 hp (149 kW) but torque was up slightly to 275 ft.lbf (373 Nm). The engine was produced until 1996.
This Cadillac V8 series was used in the following models:

• Cadillac Allante
• Cadillac Deville
• Cadillac Eldorado
• Cadillac Fleetwood
• Cadillac Seville

This engine was phased out in favor of the newer Cadillac Northstar engine in the mid-1990s.

Rear-wheel-drive Cadillacs
From 1982 to 1985, all RWD Cadillacs (except for the limousines) featured the HT-4100 V8, though this could be replaced with a 4.1 L Buick LD5 V6 or a 5.7 L Oldsmobile LF9 Diesel V8. From 1986 to 1989, the rear wheel drive Cadillacs - the Fleetwood Brougham and Brougham - used a 5.0 L (307 in³) Oldsmobile 307 carbureted V8 (replacing the HT4100). In 1990, a 175 horsepower, fuel-injected 5.7 L (350 in³) Chevrolet Small-Block V8 became available to coachbuilders. In 1991, the Oldsmobile 307 was replaced with a 5.0 L (305 in³) fuel-injected Small-Block V8; the 350 in³ Small-BlockLT1 V8 with 260 hp (194 kW), which the Fleetwood would use until it was discontinued in 1996. became available in non-coachbuilder vehicles as well. In 1993, the 180 hp (134 kW) 350 in³ V8 became standard in the newly-renamed Cadillac Fleetwood; in 1994, this was upgraded to a detuned Corvette.


HT 4100:

[Jesda]

Awesome! I love reading about this stuff. Its like what they have over at Allpar.

[gdwriter]

Interesting entry, especially considering I have a 4.9 in my '91 DeVille. I've been very impressed with it's smooth, silent operation while still managing to haul ass—and at 200K miles no less. Responsiveness is much better with the new Bosch fuel injectors from FiveOMotorsport.

Besides the larger displacement and port fuel injection, how else is the 4.9 improved from the original HT4100? Does it still have iron heads? Any ideas why Cadillac put iron heads on an aluminum block? That makes no sense.

[I~LUV~Caddys8792]

Yeah this is very good stuff!
I didnt know that the FWD Caddies were delayed until '85, and that the 4.1 was never meant to go into the RWD ones! Awesome!
It seems more logical after you learn this stuff, basically they HAD to put the 4.1 into the RWD Caddies, and it wasnt intended to go in there.

gdwriter, the 4.9 does still have iron heads.

[ben72227]

Wow, I got lots of feedback...I guess I should do engines more often...Any requests, by the way? Just PM me and I will see what I can do...

[Katshot]

Originally Posted by ben72227

Rear-wheel-drive Cadillacs
From 1982 to 1985, all RWD Cadillacs (except for the limousines) featured the HT-4100 V8, though this could be replaced with a 4.1 L Buick LD5 V6 or a 5.7 L Oldsmobile LF9 Diesel V8. From 1986 to 1989, the rear wheel drive Cadillacs - the Fleetwood Brougham and Brougham - used a 5.0 L (307 in³) Oldsmobile 307 carbureted V8 (replacing the HT4100). In 1990, a 175 horsepower, fuel-injected 5.7 L (350 in³) Chevrolet Small-Block V8 became available to coachbuilders. In 1991, the Oldsmobile 307 was replaced with a 5.0 L (305 in³) fuel-injected Small-Block V8; the 350 in³ Small-BlockLT1 V8 with 260 hp (194 kW), which the Fleetwood would use until it was discontinued in 1996. became available in non-coachbuilder vehicles as well. In 1993, the 180 hp (134 kW) 350 in³ V8 became standard in the newly-renamed Cadillac Fleetwood; in 1994, this was upgraded to a detuned Corvette.

An eagle-eyed member noticed a couple inaccuracies in this paragraph, and asked me to chime in with some clarification.

The 140hp Olds 307(VIN code 'Y', Option code LV2) was used in all RWD applications through the 1990 model year. It was replaced by the 170hp Chevy 305(VIN code 'E', Option code L03) for the '91 & '92 model years as the base engine. There was an optional engine offered starting in 1990, it was the 185hp Chevy 350(VIN code '7', Option code L05). This engine was only used for four years, '90-'93, at which time the 260hp Chevy 350(VIN code 'P', Option code LT1) took over for the final three years of production ('94-'96).

The above data was taken from Cadillac factory literature.

[ben72227]

Well Thanks for correcting me Katshot. I don't always remember EVERYTHING, so its nice to have other members fill in missing details...

[Katshot]

Are you kidding? REMEMBER EVERYTHING?! I've been afflicted with CRS for years. LOL!!! That's why they make books! All the info you have here is WAY more than anybody I know could dredge up from memory. I just happen to know a little bit of the basics and then rely on my literature to fill in the blanks!
You have a great thread here with some great info and pictures (I especially like that old Eldo).

[ben72227]

Well, I don't remember ALL of it, and I do look somethings up occasionally..., but most of it comes from memory - i just look up exact things, like engine sizes, production numbers, etc.

[Katshot]

I must admit, my memory was much better when I was 17 too. But that brings up another question. How much can you have about Cadillac history "in memory" at 17 years old?

[90Brougham350]

I understand that Cadillac wanted to keep Cadillac engines in Cadillac cars, but surely they realized then what a huge mistake putting the 4100 into vehicles like Fleetwoods and DeVilles was. Then, when things are looking good in the late 80's, why the decision to go with Chevy engines, both base and upgrade? I believe the best option for Cadillac to pursue would have been to remove the 8-6-4 from the 368 and keep it fuel-injected.

[ben72227]

I must admit, my memory was much better when I was 17 too. But that brings up another question. How much can you have about Cadillac history "in memory" at 17 years old?

Well, its simple really. I read A LOT. I'm very...different from most kids my age. While they spend their free time watching the O.C., I spend time reading about stuff. I'm a history buff too, and I read a lot about Cadillacs and the history of the automotive industry in general. I don't know everything, and I do have to look up details...but I know most of the important stuff...

[MJDART]

Great threads, I'm new to forum but I've been around Cadillacs at many times during my life. As for the engines the 500 cu in that resided in my moms 76 Eldo was unmatched in torque. Then the next year she got a black Eldo Biaritz with the 425 cu in Oldsmobile engine. It was a good engine but no where near as good. I had a '73 Fleetwood 60 Special Brouham with the 372 cu in which with carefull driving, tuning and tires delivered 15 mpg during the '77 gas shortages.

I worked in production maintenance with GM's Rochester Products Division when the Alante was introduced and I serviced the area where the fuel injection system was hand built by 1 employee for only 8 hrs a day.

My '73 Fleetwood