: 3800 series II or III swap into 79 deville?



ferrisworld
08-28-11, 07:46 PM
I was thinking of trying to swap a Buick 3.8 V6 into my Caddy and see how close I can get to 30 mpg highway. I figure the series II and series III are the most efficient, but I know I read somewhere about an 80s box caprice with the 3.8 got 29 highway. Any ideas? I don't care if it's slow.

Stingroo
08-28-11, 07:50 PM
The wiring would probably be a pain. It'd be interesting. Even a Series II supercharged 3800 can net you 26-28 highway if you drive it lightly - and 240 horses.

Then again, an LS motor could also get you close to 30 mpg highway if left stock, and would give you a LOT more torque to move the beast (plus V8 rumble... can't go wrong there.).

ferrisworld
08-28-11, 08:04 PM
Yeah but the LS would cost more.

cadillac kevin
08-28-11, 08:18 PM
you might be able to eek 30 mpg out of a vortec 350 or lt1 dependent on gearing and tune. You could get mid- high 20's easy as long as you kept your foot out of it, so it wouldnt be impossible to get 30 mpg out of either motor (with proper trans and rear gearing choices of course and maybe slightly smaller injectors)

CBodyFan
08-28-11, 08:33 PM
One of the reasons that Cadiilac's reputation tanked in the 80s was the lack of performance and reliability of the fuel economy-orientated engines: the V-8/6/4, Olds diesel, Buick V6 and the 4.1 V-8. During the first fuel embargo Cadillac sales were affected least among the full-size cars because Cadillac owners could afford the gas. The 80s saw Cadillac owners switch to Lincoln Town Car or the German makes, never to return. By switching from the durable and quiet 425 to a V-6 in a car of still ample proportions you'll just be repeating Cadillac's past mistakes. Why not use the money to have a more fuel efficient car for daily driving and leave the Coupe DeVille for leisure driving?

Stingroo
08-28-11, 08:47 PM
Look at the 5.3 liter LS motors. They're surprisingly inexpensive, relatively speaking.

cadillac kevin
08-28-11, 08:50 PM
the 3800 is a reliable engine, but there is a noticeable weight difference between a box caprice and a fleetwood brougham. also, the caprice likely had the 3.8 in it (from the 80's), which is not related to the 3800 family.
that being said, the 3800 will have to work harder than usual to pull a 5000 lbs car.
fwiw the 3.8 used in the 1980's was awful in larger cars, and most of them ended up being junked in a few years due to overheating issues on hilly terrain (too much strain on the underpowered engine). they were great on fuel mileage, but awful with respects to performance and reliability. Although, it wasn't the engines fault it was installed in a car it was never design for.

brougham
08-28-11, 09:10 PM
Youd be better off building a 350 for gas mileage. You might not car if the car is slow but that also means worse fuel mileage. If the 3.8 would work half decently in a larger car like the Cadillac and delivered good fuel mileage it would have been an option during the 90s.

jayoldschool
08-28-11, 09:18 PM
The 80s Caprice didn't get the 3800. It got the 4.3 V6. I had an 88, with OD (you could get it earlier without OD, the TH200). Got good mileage, but not 30mpg...

cadillac kevin
08-28-11, 09:24 PM
Jay, didnt some b-bodies also come with the 3.8 (IIRC lesabres did in the early 80's but I could be mistaken)

Stingroo
08-28-11, 10:08 PM
A 4.3 is a 350, without any of the benefits of being a 350. :lol:

jayoldschool
08-28-11, 11:08 PM
All the power of a four cylinder, with the fuel economy of a V8!

ferrisworld
08-28-11, 11:58 PM
Well let's see. My Deville weighs about 4750 lbs right now. I figure I could get that down closer to 4000 with some work, plus the smaller engines like the ls-1 or 3800 weigh a little less than the 425. The Caprice did have the 3.8 I think until 86, but it seems it was only available with a three speed, so I doubt it got the 29 that I had read about somewhere. fueleconomy.gov rates it at 24 mpg highway. I can't use a 5.3 because it's a truck engine and I live in California, and the FWD car 5.3 is tough to convert to RWD I think. I kind of still like the idea of the 3800, because a lot of the bigger German cars can be had with smallish engines in Europe that they don't offer here, like the 730i or whatever. but I'll probably just save until I can do the LS-1. I guess it makes the most sense over the 3800 or even the LT-1, since, if you're going to do the work, you might as well get the best engine the first time.

77CDV
08-29-11, 12:16 AM
I live in CA and was under the impression that cars covered by smog (1976+) could only have their engine replaced with an engine that was available in that model at the time it was built.

Stingroo
08-29-11, 01:17 AM
Silly Californian laws.... what is this "emissions" crap?

:suspect:

ferrisworld
08-29-11, 03:22 AM
That's partially correct. You can use an engine from any car of the same year or newer, so long as you also swap all the emissions equipment and anything else that is related to that. I don't think it's that silly. It kind of is, but I'm somewhat liberal in that I like clean air and I'm not ashamed to admit that I may have been brainwashed into thinking that cars contribute to poor air quality. That's another reason for maybe wanting to do the 3800 since I think the series III qualifies as a SULEV. Correct me if I'm wrong.

Stingroo
08-29-11, 09:09 AM
I could be wrong, but having to swap over all the emissions/electrical equipment will make your swap significantly more difficult, I would imagine.

Good luck to you.

outsider
08-29-11, 09:29 AM
I've only seen the 3800's on FWD cars...It would be pretty cool to see one swapped into a caddy :)

albymangled
08-29-11, 09:33 AM
It might be possible but why bother?

If it's economy you're looking for there are other brands perhaps more suitable.

One of the things that has always attracted me to Caddy is the big V8 engines...

csbuckn
08-29-11, 10:10 AM
Are you gonna build the motor or just swap one in? With the right cam, overdrive and rear gears, you could do good. I've always wanted to see a 3800 in a caddy. Plus you'd get a million miles on the motor.

jayoldschool
08-29-11, 11:46 AM
Losing over 700 pounds will be a serious challenge. It won't be a Cadillac anymore...

cadillac kevin
08-29-11, 01:31 PM
I'm sure you could find spots to save weight- cut unnecessary metal out of interior metal part of doors, lose some of the other structural bracing thats not that necessary (like what's done in drag cars) but when you're done it will not feel like a cadillac.
anyone know if series III 3800 parts will bolt onto the series II?
to attempt this, you'd need a series II block from a camaro or firebird and the heads, intake, etc. off a series III (with forced induction to make decent power)
and even then you'd be looking at a 260 hp/ 280 ft/lbs motor pushing a 5000 lbs car.
its totally possible to put a 3800 in the car, but it won't be cheap or a direct bolt in by any means.

Bro-Ham
08-29-11, 02:20 PM
...I'm somewhat liberal in that I like clean air and I'm not ashamed to admit that I may have been brainwashed into thinking that cars contribute to poor air quality.

I propose liberals only be allowed to walk or ride bikes for their transportation - that's the only solution to solve the clean air fantasy since if you buy into the mantra then you should be the one paying for it and setting the example. Imagine how clear and uncongested the roads would be without libs in cars - leaving more room on the road and resources for those of us who are producers to do our business swiftly and efficiently in our very large and comfortable vehicles.

As for the idea of putting a 3800 V6 in a 79 Cad, it seems to me that for any nominal increase in fuel economy or lower emissions you will pay the price of your valuable time and hard earned money in attempting to make it happen. Unless there is some special provision in the government stimulus program that will pay you to do this swap, which wouldn't surprise me, and if that is the case I will be requesting a full refund from you once obama is rebuked in the next election.

:)

cadillac kevin
08-29-11, 02:54 PM
I propose liberals only be allowed to walk or ride bikes for their transportation - that's the only solution to solve the clean air fantasy since if you buy into the mantra then you should be the one paying for it and setting the example. Imagine how clear and uncongested the roads would be without libs in cars - leaving more room on the road and resources for those of us who are producers to do our business swiftly and efficiently in our very large and comfortable vehicles.

As for the idea of putting a 3800 V6 in a 79 Cad, it seems to me that for any nominal increase in fuel economy or lower emissions you will pay the price of your valuable time and hard earned money in attempting to make it happen. Unless there is some special provision in the government stimulus program that will pay you to do this swap, which wouldn't surprise me, and if that is the case I will be requesting a full refund from you once obama is rebuked in the next election.

:)
lame political rants are lame.

ferrisworld
08-29-11, 03:28 PM
So I take it that the engine mounts from the 80s era 3.8 won't work with the series II from a camaro/firebird? From what I've seen people have swapped the FWD versions into the f-bodies without too much trouble aside from the throttle bodies being in the back etc. Series 3 has drive by wire and stuff it looks like, so a bit more work, but I like computers and electronics, so I might enjoy hooking that stuff up. From what I've read, I would save 200 lbs on the engine swap alone - 392 lbs for the 3800, about 600 for the 425.

turbojimmy
08-29-11, 03:41 PM
LT1s are a dime a dozen these days and will probably get as good fuel economy as overloading a 3.8.

Or, you can find a turbo 3.8 from '86-'87. It will tolerate 30 psi from the turbo (500 HP or so) without major machine work. Not emissions legal by a long shot. But would be a ton o fun.

ferrisworld
08-29-11, 04:29 PM
Most people with the LT-1 in a Caprice or Fleetwood, at least from what I've seen manage maybe 24 on the highway.

On another note, I've never weighed my car myself. The shipping weight for the Sedan Deville in 79 in 4212 lbs, and on one of my smog certificates the shop listed it at 4750. That doesn't seem right to me. I know the curb weight should be more, but I wouldn't think that much more.

outsider
08-29-11, 04:32 PM
yeah 24 is about what the LT1 does in the fleetwood...and that's on a good day.

csbuckn
08-29-11, 06:48 PM
Either way you look at it, a RWD caddy that gets 30mph is something I'd be interested in. You should do a 3.8 so we can see how many miles you can squeeze out of it.

Bro-Ham
08-31-11, 10:18 AM
lame political rants are lame.

It's a shame to be humorless, most liberals are by the way. :)

This idea of a 3800 in a big old Cad seems like pie in the sky. I have a 91 Olds 98 Regency Elite with the 3.8 and it's a decent engine for the car although no ball of fire. Plus, driving at highway speeds it delivers fuel economy on average of 27 mpg at 75 mph. This makes me doubt the premise of this idea of installing the same engine in a significantly heavier car and expecting high gas mileage.

N0DIH
09-01-11, 08:45 AM
I would seriously consider the 5.3L swap. The 3800 is ok, my SC3800 has got 33.5 highway (nightime, 70 mph, 50F temps, no traffic, careful driving) on a round trip. It does ok for a wrong wheel drive 3800 lb car and 2.93 gears.

But a low mileage 5.3L from car-part.com is really really hard to beat. The 5.3L's will do mid to high 20's easily mpg with OD and a truck intake and taller gears. And you have 300+ hp on tap when you nail it. The 3800 is FAR less refined of an engine. It is still a buzzy 90 degree V6, it won't change that. A 60 degree V6 is smoother (by nature). But the GM 60 degree V6's suck on power. Even the newer 3.5L and 3.9L are lame.

The SC3800 can go nicely, you will want that one over a NA 3800. But the 5.3L is cheap, very very plentiful and FAR more reliable.

ferrisworld
09-01-11, 12:28 PM
Well, like I posted earlier, I can't use the 5.3 unless I convert the FWD version since there are no 5.3s besides FWD that come in a car.

Stingroo
09-01-11, 12:33 PM
It's the same motor, isn't it? All you'd need is a RWD trans.

N0DIH
09-01-11, 01:57 PM
All 3800's are FWD bolt pattern (even ones in F-Bodies).

Find a 5.3L/4L60E (or 4L65E) and drop it in, that would be the sweet ticket.

Looking at Car-part.com found a 64k mile 5.3L (2006 engine) for $500, and a 4L60E for it with 59k for $500. So a total of $1k in drivetrain, then need some things like PCM, they are cheap, a PCM tune for it (most likely need some stuff like VATS turned off), a high pressure fuel pump and some elbow grease and you have a very very solid driving Cadillac that will go to the ends of the earth getting good mpg and be able to tow 5000 with relative ease.

Stingroo
09-01-11, 02:15 PM
No he's saying he can't swap in a 5.3 from a truck because of California laws, he COULD, however, swap one in from a car (Monte Carlo/Impala SS).

Question is, are they the same bolt pattern both ways like the 3800s? If so, that'd be the way to go.

ferrisworld
09-01-11, 02:29 PM
http://en.wikipedia.org/wiki/GM_LS_engine

It's the LS4. Different bolt pattern, and shorter crankshaft. I looked for 5.7 LS1s from 98-02 f-bodies, and you can't find lower mileage ones for less than $2,000 around here.

Actually, I guess the f-body v6 transmissions with bolt to the LS4. I don't know if the v6 4L60E can take the torque from the LS4 though. I would imagine it could.

N0DIH
09-01-11, 02:56 PM
I used to have a good article on engine swaps per state, but more or less IIRC California was engine family, with emissions needing to meet the car as a minimum, but if they knew much about it, then it might need to meet the engine.

So a 4.1 is kin to the 4.5 and 4.9L, and the 91-95 4.9L's were good on power and fuel econ (I got 27-29 highway on mine with 2.73's in my 91 Deville) and it is a near bolt in, but will need wiring changes to use the PFI, which I would use for sure. And if stock injectors, replace with 19 lb/hr Bosch's, replace on site, the stockers sucked bad. 200 hp/275 lb/ft torque. All at low rpm. But the HT4100 cars were all 3.42's, and high alt HT4100 cars were 3.73's factory.

jayoldschool
09-01-11, 02:57 PM
Go with the 4.8 version of the LSx instead of the 5.3.

N0DIH
09-01-11, 03:31 PM
Only problem is the 5.3L is made at 4x the production volumes of all other Gen III V8's combined. So the 4.8L's tend to be more costly, but it is better for mpg. 270hp to 290 hp (depending on year), can't argue with that and no multiple valves. Sorta snubs the Northstar 4.6L eh?

ferrisworld
09-01-11, 05:22 PM
But the 4.8 is still a truck engine. I guess I could just talk to some refs and see what they say. The 4.9 Caddy engine would still have to be converted to RWD, which if it isn't changed much from the HT4100 bolt wise it might go in, but the 4.8 would be better I think.

AJxtcman
09-01-11, 06:09 PM
You can always use a FWD 96 to 99 Northstar CAR engine in a RWD setup just like the Shelby S1 ran. This runs on an LS1 PCM and not the FWD Northstar PCM.

jayoldschool
09-01-11, 06:16 PM
Arghhh, who would want to spend money putting a N$ in anything?

AJxtcman
09-01-11, 06:57 PM
I am actually doing a tune for a guy that is installing a 2000 to 2005 Northstar in a Cavalier with a manual trans and we are going to run it on a 2001 LS1 PCM. The guy is up by you

What can you say bad about a 2004 plus FWD Northstar?

Stingroo
09-01-11, 10:39 PM
ZERO aftermarket.

:yawn:

Edit: Hell, I retract that statement, and revise it to NEGATIVE aftermarket.

csbuckn
09-01-11, 11:42 PM
I thought the Northstars were safer from 2005 and up. As far as head gasket problems.

I~LUV~Caddys8792
09-02-11, 12:45 AM
Yeah, those 3800's will get 30-32 mpg all day long.....in a modern, 3400 lb, aerodynamic FWD Grand Prix....not a '79 Cadillac. You might see 24-25, if you can get it installed and wired up.

I'd just save the time and effort and buy some old late '80s era beater with the 3800.

ferrisworld
09-02-11, 03:04 PM
Well, even 24-25 if a huge improvement over the 16-17 I typically see.

brougham
09-02-11, 04:02 PM
You probably won't even get that from it, and if you do it'll never pay back for the work involved.
There's no point to northstar it. It wouldn't be a huge jump if any for fuel mileage and then you'd also be stuck with a whole pile of other problems.

ferrisworld
09-02-11, 06:52 PM
Yeah, these things are all potentially true, but it's also true that payback isn't always monetary.

csbuckn
09-05-11, 10:09 AM
I still think you should do it. Then we can have some hard evidence of mileage instead of educated guesses. Either way, I think your gonna have a decent upgrade in mileage, the reliabilty of a 3800 and overdrive. Just imagine overdrive with 2.28 rear gears...sounds like 30+mpg on the highway to me. 65 mph at 1700 rpm would be nice to have.

jayoldschool
09-05-11, 10:36 AM
OD with 2.28s would be useless. The engine would be spinning way too slow to be efficient.

csbuckn
09-05-11, 12:19 PM
You think? Lower then 1700? I don't think it would be too low. What speed do you think it would run at? Isn't there a calculation to do to figure out final drive rpm? Or you could cruise at 85 if the rpm is too low for 65.

jayoldschool
09-05-11, 02:10 PM
The highest gears that ever came with an OD/RWD that I know of are 2.56s with a TH700R4/4L60(E). They are marginal, and cause the trans to constantly shift in and out of OD with any type of acceleration or hills. My best friend has this combo in his Caprice wagon, and driving it is a big difference than my identical wagon that has the trailer package 2.93s. My car stays locked in OD unless I hammer it. Mileage is the same between the two cars because my car is closer to peak torque at operating speeds.

Bro-Ham
09-06-11, 04:08 PM
Well, even 24-25 if a huge improvement over the 16-17 I typically see.

You're lucky, I have never been able to get over 15 mpg in any 425 Cadillac I've ever owned.

outsider
09-06-11, 04:13 PM
those MPG sound better than what my tired old 307 gets :$

ferrisworld
09-08-11, 05:30 PM
My dad used to have an 89 lesabre wagon with the 307. We got 23 highway.

Stingroo
09-08-11, 05:50 PM
On what planet? Did you have like, the best tuned 307 GM ever produced?

jayoldschool
09-08-11, 08:34 PM
I used to get good mileage in my 87 Caprice with the 307...

ferrisworld
09-08-11, 08:42 PM
We were probably only doing 60 - 65 in it.

csbuckn
09-09-11, 01:44 AM
So put the 3.8 in with new rear gears and see what happens. I've had plenty of 3.8s and I think they would have no problem pulling the Caddy around. Definitely one of the best daily driver motors ever made.