Hi all,

I found a 1991 Cadillac "Touring Series" brochure featuring the Allante, Seville STS, and Eldorado ETC. In it, there was a graph of the 4.9's torque curve.

From 1600-3200 rpm the torque curve is nearly flat: almost 270 lb-ft the entire time. Even at idle (750 rpms) it was producing about 220 lb-ft!

This should come as no surprise to 4.9 owners who find instant response when they stab the throttle. The torque curve is one of the flattest I've seen.

Cool! Thanks for the info! I was always wondering what the 4.9's torque curve looked like.
Could you scan a picture?

I will try, although it may be a while: I lent the brochure to a friend. When I said flat torque curve, though, I meant VERY flat.

that engine was designed for pulling around heavy cars with ease, and it does that well with a little bit of extra.

Yeah, Caddy 4.9 and Jeep 4.0 both have a very similar, very flat torque curve.

I miss the 4.9, it was a darn good engine, tho the Ford 4.6 produces nearly the same numbers (10 extra hp) from less displacement, it's much more refined, which I guess is a good and bad thing... the 4.9 had a really nice raspy sound to it, not ala redneck stright pipes on a pickup... but, well ya'll 4.9 owners know what I mean. Plus the throttle response of the 4.9 was pretty good for what it was too.

4.9 would make an awesome off-road engine, it's been done before in both Isuzu and Toyota, not the easiest as there are no kits avalible as other engines, but the PFI, realitive ease of getting electronics to work and.... the torque and torque curve make it a great truck/off-road engine.

I kinda want to drive a 4.9 Caddy again just for the heck of it.

When i first got the Deville, I noticed the pedal was a little more tight in comparison to a Lesabre i was driving before it.

I think they did this at the factory to keep granny from melting the tires on her way to the beauty parlor if the weight of a foot was all that was required. Thats the torque on the 4.9

I never seem to have to stomp the pedal to get that car going. I never hear that engine huffing either. Moving the 4600 pound car around and getting it to speed is no work for that motor, No work at all.

I start from red lights easy and simply progress pressure on the pedal evenly, Never stomping on it ,and when i think im at about 40 mph i look at the speedo and its in the 50`s. Knock on wood no tickets yet, But im used to "feeling" the engine work to tell me my relative speed and adjust pedal pressure that way, But at the speeds mentioned, This motor is just not working hard at all...at all!! i don`t think the pedal gets pushed past the 1/32th mark of its travel to get going like that..... I love it!

I start from red lights easy and simply progress pressure on the pedal evenly, Never stomping on it ,and when i think im at about 40 mph i look at the speedo and its in the 50`s.

That sensation is one of my favorite things about the 4.9, God I miss being able to do that!

I remember reading somewhere that when Cadillac came out with the HT4100 in the early '80s, the engineers knew how little torque that engine made, so they made the throttle cables shorter so it would take less throttle to get moving, which made it seem as though it was pretty torquey, and you'd feel that.....until you jammed the throttle to the floor to pass someone and then realized how much of a dog those are in those big heavy D Bodies.

220 lb-ft at idle? Man, I always wondered why I beat a 540i off the line in my '94 DeVille! I've got 154,000 miles on my 4.9L, and it is honestly the best running engine in our fleet of cars, including a 2002 Silverado with 51,000 miles! Even the original Hydra-matic 4-speed automatic transmission has never been rebuilt and it shits great. Uncompromised performance, and a very reliable runner. Makes a great daily driver even with the high miles!

I love how when i'm in first gear before the transmission shifts to second doing about 20 mph when i stab the pedal the front lifts and the tires squeal for about half a second and then the whole car takes off.

I was wondering how much off idle torque this engine made.

It makes sense that every time my foot gets a little excited after the light turns green the rear squats and the front end jumps up until I back off just a little.

Anyone who doesnt know the specs will swear this thing makes over 200 hp, but its really the plethora of torque in first gear.

I looked at the specs for the Jeep 4.0 and @ 3200 rpms it makes 235 lb-ft with 190 hp @ 4600 rpm, also has a higher redline than the caddy @ 5300.

I'll take torque over horsepower anyday. Torque seems like it builds faster and gives you that raw kick in the butt push your head back feeling,

I love it!!!

I'd love to see a scan of that.

still no scan? :(

no scanner to scan with

here ya go. No charge (this time any ways)

http://www.geocities.com/shawn_kato/image/l26-2.jpg

Thanks. That's awesome. :cool:

yeah thats a curve alright.
looks like over 250 ft-lbs at 2k rpms

I had heard it was flat, I just didn't realize how flat it was. No wonder it pins me to the seat all the way accross an intersection! It pushes a 2800 Lb car very nicely, and with the weight distribution it just hazes the tires. Fun stuff!

The 4.9 is a wonderful engine to drive. Response is instantaneous, and it stays there.

Now, I have to wonder wehat the torque curve looks like ton the other engines, particularly the 4.5 I have with my '88 Eldo. That engine is also very responsive. But I have eliminated the convertor and running 14BTDC base timing which makes for a nice raspy exhaust and instananeous throttle response.

But, I have to admit, one of the very nicest Cadillacs I drove (other than the 472 in my '70 Fleetwood) is the '91 Eldo Touring coupe. The 4.9 in that light car made for some thrilling driving.

Mike

The 4.9 is a wonderful engine to drive. Response is instantaneous, and it stays there.

Now, I have to wonder wehat the torque curve looks like ton the other engines, particularly the 4.5 I have with my '88 Eldo. That engine is also very responsive. But I have eliminated the convertor and running 14BTDC base timing which makes for a nice raspy exhaust and instananeous throttle response.

But, I have to admit, one of the very nicest Cadillacs I drove (other than the 472 in my '70 Fleetwood) is the '91 Eldo Touring coupe. The 4.9 in that light car made for some thrilling driving.

Mike

One of the biggest reasons the '91 Eldo Touring coupe felt so fast was the different (higher numerical) gear ratio. In addition, they have a quicker steering rack, rear sway bar, larger front sway bar and lower profile/wider tires. I found one of these cars at the junkyard and transfered all these goodies over to my 88 Eldorado except the different gear ratio because that would have involved changing over the transmission. There would have also been a gas mileage penalty which is not good with these astronomical gas prices these days.

The 4.9 has 200 hp while the 4.5 in our Eldorado's has 155 hp. However, the 155 hp in my Eldorado will run circles around the 170 hp 4.1 in my Allante.

Did you notice any power improvements from eliminating the converter? I still have mine on but replaced the stock muffler with a Flowmaster. I also advanced the timing to 13BTDC and run 87 fuel.

I also advanced the timing to 13BTDC and run 87 fuel.

I believe if you would advance it to 13BTDC you would have to (and their are no exceptions) run 93 oct or risk severe engine knocking and possible engine failure so if you one of those people that pinch pennies with their 4.9 and run 87 in it (it does require premium to run efficiently and healthily) than advancing the timing is not what you would want to do.

I believe if you would advance it to 13BTDC you would have to (and their are no exceptions) run 93 oct or risk severe engine knocking and possible engine failure so if you one of those people that pinch pennies with their 4.9 and run 87 in it (it does require premium to run efficiently and healthily) than advancing the timing is not what you would want to do.

Nope, I've got one of those early low compression/low horsepower 88/89 4.5 engines. I timed it by listening to it. If I used premium fuel, I probably could get by with even more advance.

The car had the convertor cut out of it when I got it. I sorta saved it from the wreckers. It was far to nice to scrap. The reason why it was going was that the dash was out. I diagnosed it to the CPS module, found one for $25 at the wreckers and it's been fine.

I had a pipe welded in place of the convertor. From previous experience with these cars, it does help in the mid to high range engine speeds where breathing is more important. I know the TBI 4.5's use the smaller port heads, though.

It runs very well on regular 97 octane as well. I have also advanced the timing on my parent's '82 Fleetwood, and it runs much stronger. And on regular.

Mike