It sure is a shame about the 4.5 and 4.9 not being hotrodable

[The Fred]

I really like the way they drive and sound

I really love the older Seville body style

It sure would be nice if they would lend themselves more to performance modifications

[bobnsue2]

I really like the way they drive and sound

I really love the older Seville body style

It sure would be nice if they would lend themselves more to performance modifications

--------------------------------------------------------

Well heck our 91 STS 4.9 certainly doesn't need any performance help. It really goes like a rocket as is.

Bob B

[BodybyFisher]

Your STS has dual exhausts, or is it a single with dual outlets out of the muffler system?

I was going to say that myself, my 91 while it only had 200 HP was quite powerful.

I would imagine that you could make it 'sound' more powerful with a cat back system.

[Ed Hall]

The bottleneck on these engines is fuel management and the valve train. The stock valve train cannot handle much over 4500 rpm. One way to get around this is install a set of heads from a Allante. This will be good to about 5500 rpm. A more radical approach might be to modify your heads to accept a set of Ford roller rocker arms http://www.fieroaddiction.com/caddy49h.html

Once you modify the valve train to be able to handle more rpm's, then you can install a camshaft that'll give more top end power. However, this will decrease low rpm torque unless you install a set of Rhodes Lifters http://www.rhoadslifters.com/ Rhodes lifters work on the same principle as Honda V-tech -- Low lift at low rpms for more torque and high lift at high rpms for good horsepower.

For fuel management, I would go with a fully programmable Do-It-Yourself electronic fuel injection controller called Megasquirt http://www.megasquirt.info/ This system could be piggybacked onto the existing Caddy fuel management system so all the displays in the car would be able to be retained. Now your fuel management is able to fuel a turbocharger.

[The Fred]

I've seen the STS and I don't remember any different looks outside of maybe some emblems and maybe the grille and amber in the tails- I've heard they might have beefier suspension and brakes?

My 4.9 automobiles were plenty powerful until you were over about 45mph... it is just a shame that a guy can't get a 4.9 up around 300

The bottleneck on these engines is fuel management and the valve train. The stock valve train cannot handle much over 4500 rpm. One way to get around this is install a set of heads from a Allante. This will be good to about 5500 rpm. A more radical approach might be to modify your heads to accept a set of Ford roller rocker arms http://www.fieroaddiction.com/caddy49h.html

Once you modify the valve train to be able to handle more rpm's, then you can install a camshaft that'll give more top end power. However, this will decrease low rpm torque unless you install a set of Rhodes Lifters http://www.rhoadslifters.com/ Rhodes lifters work on the same principle as Honda V-tech -- Low lift at low rpms for more torque and high lift at high rpms for good horsepower.

For fuel management, I would go with a fully programmable Do-It-Yourself electronic fuel injection controller called Megasquirt http://www.megasquirt.info/ This system could be piggybacked onto the existing Caddy fuel management system so all the displays in the car would be able to be retained. Now your fuel management is able to fuel a turbocharger.

I'll be damned,

I've always known that these motors hate high RsPM but I never knew why

[Bruce Nunnally]

A while back, ASG in Indianapolis was doing some hot rod 4.9L's:

http://www.angelfire.com/stars/mycaddy/asg.htm for around 285hp.

The same hotrodding questions apply: How much money do you want to spend? How fast do you want to go?

The 91/92 STS with 4.9L at 200hp is a great car as designed. Even with the more hp from the ASG or similar, in the simulations the STS did not get measurably quicker unless you changed the gearing or the rev limit. Note that the STS did have a more aggressive final drive ratio than the Seville of the time.

If you want to build up a street racer from a cadillac you can, but it will cost money, although you will have a unique car when you are done. I would recommend you start with a 96 Fleetwood Brougham, with the LT1 engine, since there are a ton of mods available for that powertrain. Then you can upgrade as you go. It does weigh a lot more than the 91/92 Seville, and does not have the same look, but would be less expensive to hotrod.

Another approach is to put in a supercharged V6 from a Grand Prix GTP, or even more ambitiously a new FWD 5.3L powertrain from the Impala. You will have to redo the dash, but it would make a nice runner.

Tuner shops can make very nice 600+hp engines out of the 472/500 cubic inch engines from the mid70s, albeit with gallons per mile instead of miles per gallon of fuel usage. But a 600+ hp 1976 convertible would be a fun car to get around in.

[The Fred]

I love this message board.

[thu]

Yes, it seems that this board has a much higher 'Signal To Noise' ratio than the other Caddy Board. It also loads a heck of a lot faster, too.

[The Fred]

You said that right,

These guys know their stuff I tell you what

And there aren't thousands of rude ignorant *smurf* like there were on the other board I was on.

The only good thing about that board was that it could be hillarious to throw some *smurf* back at them now and them but it sure was a waste of good time

[The Fred]

That website is right mine doesn't even make it to 4500rpm before shifting (I have the 90 with the 180hp version of the 4.5)

It aint difficult to put heads from the Allante on there, right?

I wonder if it is easier to put them on the 1990 4.5 or the 1991 4.9

The allante 4.5 was a variation of the regular 4.5 was it not... I mean a variation but pretty much its own?

[The Fred]

A while back, ASG in Indianapolis was doing some hot rod 4.9L's:

http://www.angelfire.com/stars/mycaddy/asg.htm for around 285hp.

The same hotrodding questions apply: How much money do you want to spend? How fast do you want to go?

The 91/92 STS with 4.9L at 200hp is a great car as designed. Even with the more hp from the ASG or similar, in the simulations the STS did not get measurably quicker unless you changed the gearing or the rev limit. Note that the STS did have a more aggressive final drive ratio than the Seville of the time.

If you want to build up a street racer from a cadillac you can, but it will cost money, although you will have a unique car when you are done. I would recommend you start with a 96 Fleetwood Brougham, with the LT1 engine, since there are a ton of mods available for that powertrain. Then you can upgrade as you go. It does weigh a lot more than the 91/92 Seville, and does not have the same look, but would be less expensive to hotrod.

Another approach is to put in a supercharged V6 from a Grand Prix GTP, or even more ambitiously a new FWD 5.3L powertrain from the Impala. You will have to redo the dash, but it would make a nice runner.

Tuner shops can make very nice 600+hp engines out of the 472/500 cubic inch engines from the mid70s, albeit with gallons per mile instead of miles per gallon of fuel usage. But a 600+ hp 1976 convertible would be a fun car to get around in.

Those FWBs are gorgeous Cadillacs

Is the 1996 the only one with the LT1?

How many horsies are under there to begin with?

Does the LT1 they use have those roller rocker things?

Ok I see now that it is in the 1994-1996 FWB and around 300HP.. right?

So how does the stock LT1 compare along side of the N* in the STS?

Aw heck, now it looks like they used a 260HP LT1 in there,

Is it easier to buy a big built up crate and put into the FWB or into a 90-91 Seville?

[Ed Hall]

That website is right mine doesn't even make it to 4500rpm before shifting (I have the 90 with the 180hp version of the 4.5)

It aint difficult to put heads from the Allante on there, right?

I wonder if it is easier to put them on the 1990 4.5 or the 1991 4.9

The allante 4.5 was a variation of the regular 4.5 was it not... I mean a variation but pretty much its own?

The heads from an Allante will fit. It's basically the same head with stiffer springs and some stronger parts to handle the extra rpm's. This engine also used a different intake manifold that looks like:

http://cgi.ebay.com/ebaymotors/Cadillac-Al...020326600QQrdZ1

[The Fred]

That website is right mine doesn't even make it to 4500rpm before shifting (I have the 90 with the 180hp version of the 4.5)

It aint difficult to put heads from the Allante on there, right?

I wonder if it is easier to put them on the 1990 4.5 or the 1991 4.9

The allante 4.5 was a variation of the regular 4.5 was it not... I mean a variation but pretty much its own?

The heads from an Allante will fit. It's basically the same head with stiffer springs and some stronger parts to handle the extra rpm's. This engine also used a different intake manifold that looks like:

http://cgi.ebay.com/ebaymotors/Cadillac-Al...020326600QQrdZ1

I've seen that before..

Looks like it is from outer space

[Bruce Nunnally]

The Fleetwood Brougham in 94-96 used the 260hp LT1. It was a very very similar car to the Impala SS of those years, although the Fleetwood was extended (longer). Many if not all of the performance parts for the Impala SS will also play fine on the Fleetwood.

Generally, a stock Northstar STS is quicker than a stock Impala SS. However, there are few stock Impala SS's.

Background reading:

http://mph-online.com/mag/rearview/007

also:

http://members.accessus.net/~090/cfb.html

The 93 version had a TBI engine for 185hp.

Shop for a car with the VP4, Trailor towing option as it had a better final drive ratio.

The LT1 would be easier to swap to another chevy V8, like an LS1 or LS2. However, there are mod parts to build the LT1 up to an LT4, or blower kits available, and custom tuning.

[KHE]

Those FWBs are gorgeous Cadillacs

Is the 1996 the only one with the LT1?

How many horsies are under there to begin with?

The '94 - '96 Fleetwood and Fleetwood Broughams had the LT-1 engine. It had 260 HP stock.

[The Fred]

The Fleetwood Brougham in 94-96 used the 260hp LT1. It was a very very similar car to the Impala SS of those years, although the Fleetwood was extended (longer). Many if not all of the performance parts for the Impala SS will also play fine on the Fleetwood.

Generally, a stock Northstar STS is quicker than a stock Impala SS. However, there are few stock Impala SS's.

Background reading:

http://mph-online.com/mag/rearview/007

also:

http://members.accessus.net/~090/cfb.html

The 93 version had a TBI engine for 185hp.

Shop for a car with the VP4, Trailor towing option as it had a better final drive ratio.

The LT1 would be easier to swap to another chevy V8, like an LS1 or LS2. However, there are mod parts to build the LT1 up to an LT4, or blower kits available, and custom tuning.

Those Fleetwoods sure are expensive ... but worth it

Say I buy a Fleetwood with the LS1.. what would it take to get it to something at least reasonable over 400HP?? I've driven a few 300 horse automobiles and it just aint enough for when you need it.

Also, what does it take to make the thing behave when you want it to? There are times when you want your Cad to purr quietly and all Could you put a couple mufflers on a built up motor and make it quiet? (And have a cutout for when you wanted to get with it)

[Bueno]

I really like the way they drive and sound

I really love the older Seville body style

It sure would be nice if they would lend themselves more to performance modifications

It's not that kind of car. If you want something to go fast and don't mind being *** hammered again by GM, buy a Camaro or a Vette.

[Bruce Nunnally]

The problem with the Fleetwood is weight; it is 4200-4400 lbs. With a $5K + install supercharger alone apparently an otherwise stock Impala SS can hit 390 wheel hp, which would be around 450 crank hp, through factory mufflers.

Ideal would be to find a pristine Fleetwood with a engine problem, get it at a discount, then install a tuned 383 cubic inch LT1 with 400+ hp normally aspirated for 5K. Still not cheap, but fun.

[The Fred]

I really like the way they drive and sound

I really love the older Seville body style

It sure would be nice if they would lend themselves more to performance modifications

It's not that kind of car. If you want something to go fast and don't mind being *** hammered again by GM, buy a Camaro or a Vette.

If it's not a Cadillac it's not in my driveway/garage/posession/consideration

If anyone tries to "*** hammer" me I get out some guns and tell them that it is a bad idea to try that

The problem with the Fleetwood is weight; it is 4200-4400 lbs. With a $5K + install supercharger alone apparently an otherwise stock Impala SS can hit 390 wheel hp, which would be around 450 crank hp, through factory mufflers.

Ideal would be to find a pristine Fleetwood with a engine problem, get it at a discount, then install a tuned 383 cubic inch LT1 with 400+ hp normally aspirated for 5K. Still not cheap, but fun.

Good idea.. I could get the 383 and could I use a TH400 with it..? I love the Thm 400

And what could I get for the cores that come out?

Can I get some tires that will actually get ahold of the road?

[Bruce Nunnally]

I think the Fleetwood Brougham used the 4L60e transmission.

Check http://www.cmotorsports.com/94-96-impala/94-96-impala.html for a ton of Impala parts for these cars, including racing transmissions.

The optispark ignition is often mentioned as a weak area.

[Ed Hall]

It you want power, buy a mid 80's Cadillac Fleetwood with the 4.1. Rip out the engine and in it's place, install a 500 cubic inch Cadillac engine. Then hook this engine up to a 4 speed 4L80E transmission for better drivability and fuel economy. There are many performance parts for the Caddy 500.

[Bruce Nunnally]

BUT, the LT1 will get 25+ mpg on the highway; the 500 will get 14 mpg or less?

On the other hand, it would make a nice all-Cadillac project, and definitely a fun car.

[BodybyFisher]

I found this info on the LT1:

LT1

In 1992, GM created a new-generation small-block engine and again called it LT1 to recall the 1970 LT-1. It displaced 5.7 liters and was a 2-valve pushrod design, although a 4.3 liter variant known as the L99 was also offered beginning in 1994. The LT1 was unique with a reverse-flow cooling system which allowed for the engine to run at a higher compression. This was accomplished by cooling the heads first, thus reducing the risk for engine knock at the higher compression.

Other cars received detuned versions of the LT1 in the years following 1992. In the Camaro and Firebird, the LT1 engine produced 275 hp (205 kW) and 325 ft·lbf (441 Nm), with the Corvette and Ram-Air Firebird getting 305 hp (227 kW). The Camaro was up to 285 hp (227 kW) and 335 ft·lbf (454 Nm) with this engine in the 1996 model year with the addition of dual catalytic converters. In the 1994 to 1996 B-body (Impala SS, Caprice and Roadmaster) and D-body (Fleetwood) version, the LT1 engine produced 260 hp (194 kW) and 330 ft·lbf (447Nm).

There were a few different versions of the LT1. All feature a cast iron block, but only the Corvette and F-bodies got aluminum heads. 1994 saw new sequential port injection and a mass airflow sensor. A new vented version of the opti-spark distributor appeared in 1994 on the B-Bodies and Fleetwood and in 1995 on the Corvette and F-Bodies. 1996 saw major revisions for OBD-II - a second catalytic converter on the F-body cars(which was standard since 1993 in California), a crank position sensor, rear oxygen sensors, and a new computer. Some OBD-II features had been added to the Corvette starting in 1994 for testing purposes. The 1997 model year Camaro and Firebird were the last year for this engine in a GM production car.

This engine was used in:

Aluminum heads and 4-bolt mains

1992-1996 Chevrolet Corvette C4

Aluminum heads and 2-bolt mains

1993-1997 Chevrolet Camaro Z28/Pontiac Firebird Formula and Trans Am variants

Iron heads and 2-bolt mains, 4.3 (L99) and 5.7 liter options

1994-1996 Buick Roadmaster (LT1 only)

1994-1996 Cadillac Fleetwood (LT1 only)

1994-1996 Chevrolet Caprice (LT1 or L99)

1994-1996 Chevrolet Caprice Police Package (LT1 or L99)

1994-1996 Chevrolet Impala SS (LT1 only)

[epricedright]

My '96 Impala SS had the LT1. Man that car was a rocket and would handle like no other car I've owned! I hope to replace her one day, if I can find one in mint condition.

[estretcha]

There is a company in North Carolina that makes custom headers for the 4.9 at a price of around $500. These will add about 10 HP. Their website is www.freewebs.com/evoengineering

I plan to add these to my 1994 Deville along with a high flow dual exhaust system, a tuning chip, and a cold air intake system. These mods could add 35-40 HP.