What is the difference between the 4.9 & northstar caddy engines? I'm sure performance is going to be the first answer, so we'll skip that one. Do they both bolt right up, what mods are different? If I go with a 4.9 now & put a N* in it at a later date, do I need to change the wiring harness and ecm again? Does the 4.9 have headgasket problems like the N* do? I know about the N* mods from asking these type questions before, but is there any difference in mounting the 4.9? If there are any links that pertain to this subject would be much helpfull. Thanks for your help once again.

I forgot to add that this swap is going into a '88 5speed car so I also need to know if there are any different mods for the flywheel/clutch assembly versus what needs to be done for the N*. Thanks again.

Totally two different beast. The only things they share are;

1. V8.
2. V8 Sound.
3. Cadillac motors.
4. Fit inside a Fiero

Everything else is different;
1. swap difficulty.
2. Computer/harness.

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"Friends don't let friends drive stock"

Completely different engines.

4.9 - Alluminum block with cast iron heads and cylinder sleeves. Lightweight for a V8 at ~375lbs ready to install. Pushrod motor. Very simple install, fits better in fiero then N*. Little aftermarket support. Slightly more low-end torque then stock N*. Little upper end power. Inexpensive to buy and install.

N* - DOHC engine. Much more power in upper RPM range. Lots of aftermarket support. Heavier then 4.9. Tougher and more expensive to install then 4.9. MUCH more HP potential then 4.9. Usually much cleaner looking install then 4.9. Higher CG (center of gravity) then 4.9.

Both motors make great swaps for a fiero. Both engines have aftermarket flywheels available off the shelf. If your willing to spend more now and go N* you have a tons more upgradeability for the future. The 4.9 makes an excellant, reliable daily driver. Its really about personal preference. Good luck on this decision.

[This message has been edited by Fieroseverywhere (edited 01-27-2009).]

Since both engines were offered in the same chassis, IF you built the mount brackets on your cradle to accept the Caddy engine mounts, you could conceivably bolt a Northstar in for a 4.9.

The engines have different crank flange bolt circles and require different flywheels.

They are radically different electrically.

In an '88, you will be required to trim the right strut tower to clear the Northstar cylinder head and cam cover.

[This message has been edited by Will (edited 01-27-2009).]

I have been following the 4.9 and N star swaps for years and I suspect that the price of the N star swap is as much in weight added as money gone from your wallet.
When my wife gets out of school I hope to do a swap with the new GM High Feature 3.6L V6. Yeah. It's not a V8, but it's lighter than the N star and has direct injection, 300 hp and a 6 speed automatic. The gearing is set for good highway mileage so top speed should be way up there too.
The 4.9 swap apparently has no weight penalty but that is a lot of work for an engine that still has 20 year old technology and only 200 hp.
10 pounds per horsepower is a minimum if you don’t want to risk being embarrassed by a soccer mom in a modern family sedan. Fieros are around 2750 pounds so 200 hp doesn’t quite fill the bill.
I am expecting to read here about the first High Feature 3.6 swap any minute now

quote Originally posted by gem1138: I have been following the 4.9 and N star swaps for years and I suspect that the price of the N star swap is as much in weight added as money gone from your wallet.

Are you implying that the engine is as much heavier as it is more expensive? lbs to dollars is a difficult comparison to make. The Northstar is really not that heavy.

The 4.9 is the easiest swap out there with the exception of the 3.4. 200hp is not much by todays standards but it is a motor built for low-end torque not HP so who cares. If one really wanted a race motor they shouldn't waste their time with a 4.9 or N* IMHO. If you want a cheap and easy swap that is a significant upgrade above the stock fiero engines the 4.9 a very good option. NO soccer mom will ever embarrass me since I won't be spending my time doing any racing on the street. Let alone against any minivans or SUV's.

I've said it before and probably say it again. HP means nothing. Driver skill trumps all. Build the car for its intended purpose and go with what you think is the right choice. Any engine swap will only make your fiero more fun then it already is.

The 4.9L is an OLD engine design. As such parts are getting scarce and expensive. Its also very difficult to rebuild this engine and even more difficult to modify it for power. A SBC its not but its an inexpensive and reliable engine with gobs of bottom end torque and has the capability to give great hwy gas mileage. The N* is a far more modern engine but a much tougher and expensive swap. The other V8 engine choice is the LS4 FWD V8 and of course the RWD SBC varations that V8 Archie specializes in.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: The 4.9L is an OLD engine design. As such parts are getting scarce and expensive.

Since when?? I haven't experienced any shortage/high prices for 4.9 parts or Fiero engine parts for that matter.

quote Originally posted by jscott1: Since when?? I haven't experienced any shortage/high prices for 4.9 parts or Fiero engine parts for that matter.

The 4.9L has been off the market for 14 years. Parts can still be found but it may be safe to conclude that not many auto parts dealers stock them. Say that you need a water pump. It is doubtful that you'll find one locally. I should have said some NEW internal rebuild parts for the 4.9L are indeed expensive like a cam, rods and pistons. Others are comparably priced. Used parts are usually inexpensive but a new long block will run you about $3200 + shipping.
If one can find a good used 4.9L and swap it in, it is obvious the 4.9L engine gives great performance for the price.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

The 4.9 is a little like a toothbrush. If it fails you pick up another one for $300

Arn

quote Originally posted by Dennis LaGrua: The 4.9L has been off the market for 14 years. Parts can still be found but it may be safe to conclude that not many auto parts dealers stock them. Say that you need a water pump. It is doubtful that you'll find one locally. I should have said some NEW internal rebuild parts for the 4.9L are indeed expensive like a cam, rods and pistons. Others are comparably priced. Used parts are usually inexpensive but a new long block will run you about $3200 + shipping. If one can find a good used 4.9L and swap it in, it is obvious the 4.9L engine gives great performance for the price.

...you should come in from left field once in a while, because I have no ideal where you get your information...

water pump, I can walk into any parts store around me and buy one off the shelf. Internal parts are also not expensive, I rebuilt mine, and the cost was very similar to me rebuilding a 305/327/350 - in fact I can walk into my local speed shop and get all parts to rebuild it same day or the next. Even some parts I thought I would have to order, rocker bridge, the dealer had "in stock" and on the shelf.

A new LS4 (as you are so good at pointing out) long block is in the same price range (if not more).

They are not that hard to rebuild "if you are competent", there are a few things you have to be aware about, but nothing that requires special tools that a person who has rebuilt a motor before does not have.

JUST BECAUSE THE 4.9 IS AN OLD DESIGN DOES NOT MAKE IT BAD - you are older than it is so don't talk
(BTW, the Fiero is even older, so why do you own one when there are so much better cars out there?).

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

That being said, and back on topic - if you are thinking N*, go this way in the first place, there is no point in wasting money on the 4.9 install only to change it in a year or 2. The N*, from what I have seen, also requires cradle mods, plus I am not sure if the ECM for the 2000+ years has been hacked yet (probably, but I do not follow this too closely).

You first need to decide what you want to build the car for. My impressions of the N* is that it is not really a daily driver (this is from actually seeing/touching one) - granted this was a 5 speed car, so an auto might be better. But, the fun factor is just so The 4.9 is a way better as a daily driver and it is tough to beat off the line (the 300 ft/lbs torque helps big time here), but don't past up looking at the 3800SC and the 3.4 DOHC - these are quick cars, sure they may not have the bottom end torque of a V8, but they can be fast in the 1/4 mile.

[This message has been edited by Mickey_Moose (edited 01-28-2009).]

quote Originally posted by Dennis LaGrua: Say that you need a water pump. It is doubtful that you'll find one locally.

Picked one up IN STOCK at my local AutoZone yesterday. $42. Didn't have to order it, they had it. My town has less than 10,000 people. Have had to get other parts as well, never a problem. Can't imagine that if a small town AutoZone has the parts that there will be a problem for a while.

quote Originally posted by Dennis LaGrua: The 4.9L is an OLD engine design. As such parts are getting scarce and expensive. Its also very difficult to rebuild this engine and even more difficult to modify it for power. A SBC its not but its an inexpensive and reliable engine with gobs of bottom end torque and has the capability to give great hwy gas mileage. The N* is a far more modern engine but a much tougher and expensive swap. The other V8 engine choice is the LS4 FWD V8 and of course the RWD SBC varations that V8 Archie specializes in.

1 Simple Question... Have you ever done a 4.9 Swap or even ridden in one that was done?

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Found a Red 84 4speed, Waiting to get a house so I can re-home it
There are Two kinds of Fiero's : Notchies and Donors!

I think Dennis is just trying to rattle our cages.

Yes the 4.9 is out of production, but so is the 3800SC, the 3.4 pushrod, 3.4 DOHC, etc. And parts availability is a complete non-issue.

The Northstar is a big engine, and requires some cradle modification to fit. Just because Caddys came with 4.9 and Northstar does not mean they are completely interchangeable in a Fiero.

quote Originally posted by jscott1: I think Dennis is just trying to rattle our cages. .

Either way I just wanted a yes or no. if it was a no i would politely ask him to refrain form 4.9 threads. If yes I woiuld ask him WTH makes it a bad choice?

I have a 4.9/4t60e drivetrain in my Formula, installed some time ago by Ed Parks at the Fiero Factory for the previous owner. Extremely reliable, very powerful, pulls like a train from a dead stop to as fast as you want to go. Engine has about 130,000 (if I remember correctly), uses no fluids, no leaks. I would not hesitate to get in the car on a moments notice, and drive anywhere, any distance.

The engine doesn't make a lot of RPM, but makes big torque. I am not a fan of autos in Fieros, but the caddy trans is a great way to go with the 4.9, as the gearing takes advantage of the torque curve of the motor. It pulls just as hard from 80 to 120 as it does from 0 - 40. or 40 - 80.

I also have a N*/4t80e drivetrain in my 95 Seville STS. The car weighs about 3850, and is a rocket. The motor just comes alive above 4000 RPM and doesn't run out of breath - shifts at 6500 when you have your foot to the floor. 70 to 140 is effortless, the speedo winds up almost as quickly as the tach. Engine is rated at 300 HP/295 TQ, in the 4400 - 4800 RPM range (again, if I remember correctly). The car has 202,000 miles, uses very little oil (1 qt per 3000 miles), no leaks, and has been ultra reliable and drives like new.

This engine likes the top end but still makes great torque, and would be a better choice for a manual (Getrag or 6 speed).

The 4.9 is a relatively inexpensive swap, whereas the N* is much more involved, and expensive.

I hope this information helps you as you ponder your options.

Joe

last time i checked 3.8's hang with 4.9's and northstars just fine... i like watching them fade in the rear view...lol tim..

Thanks for the replies. Didn't mean for it to be such a heated discusion . How much change do I need to make in the wiring harness for the 4.9? Also, does the 4.9 have headgasket problems like the N*? Thanks.

quote Originally posted by Turbowedge: Thanks for the replies. Didn't mean for it to be such a heated discusion . .

I know you didn't mean to...but "what's the best engine" is a hot button topic on this forum as everyone defends their favorite swap against all criticism.

You can get all the info you need on the wiring from the Archives. Micky_Moose has a set of drawings that I downloaded. Very detailed and you can make your own harness.

I've had no issues with head gaskets, I don't think that's a common problem with 4.9s.

quote Originally posted by Turbowedge: Thanks for the replies. Didn't mean for it to be such a heated discusion . How much change do I need to make in the wiring harness for the 4.9? Also, does the 4.9 have headgasket problems like the N*? Thanks.

Not your fault. Engine choice is always a hot topic. Too many opinions and biased info floating around.

The 4.9 harness is easy once you get into it. I haven't heard of head gasket problems either.

Dennis: The 4.9 was Caddy's only engine for a few years. Used in every caddy available. This means they are plentiful as well as cheap. Not as plentiful as a N* but not in any way coming up on a shortage. I rebuilt my 4.9 also. It cost me less then it does to rebuild a 2.8. An upgraded cam is available for under $200 also.

Both are amazingly better than the stock duke or 2.8.
Both require custom mounts, flywheels, wiring and the N* requires cradle modification.
N* is a more "exotic" swap that will be faster
4.9 is a GREAT daily driver engine with a nice amount of power but will not be as "fast" overall as the N*
N* engines usually cost more than the 4.9 and can only easily be used with Getrag manuals as far as I know. Of course it can be used with the auto tranny it came with but why would you do that with a 32 valve DOHC V8 .
i also think the 4.9 gets better mileage but not a lot 2~3 mpg.

[This message has been edited by IROCTAFIERO (edited 01-28-2009).]

I commented yesterday in this thread that the N star was the heavier choice. Am I mistaken in this belief?
I have come to believe this because I have read in N star threads of the need to upgrade brakes and modify the suspension to compensate for the weight increase.
I have not read of this being deemed necessary with the 4.9 swap.
I mentioned this before and again now because anyone making this decision should know the answer to this question.
A slight aside: I settled reluctantly on an 88 with an auto because it only had 30k miles on it and the price was right. I have no regrets. I know I shouldn’t, but I occasionally talk on my cell phone while driving, and that leaves no hand free for shifting. Also, with the Fiero’s heavy steering, it is better to have two hands doing the work.
Regardless of the 4.9/N star choice, sticking with the matching auto sounds much simpler and with all of that torque, an auto should be fine.

Yes, the 4.9 weighs less
IIRC, the 4.9 weighs less than the 2.8

quote Originally posted by IROCTAFIERO: IIRC, the 4.9 weighs less than the 2.8

6lbs less

Thanks for the continued info. Is there anyone trustworthy that can build a plug-n-play harness for either option (4.9/N*), for me if I sent the original? What are the cubic inches of the N*? Is it that much bigger than the 4.9, or is it in the heads? I am getting the impression from the feedback that the N* isn't really meant for a daily driver. Not saying that I will drive it everyday, ( I do have two Grand Nationals), but it will see a lot of driving time. I want to do this swap and not have to worry with it for awhile. If it means going with a smaller engine (4.9), then I rather do that then keep wrenching on it all the time. If I wanted that, I would buy a Harley . Please no hate mail, just a joke. Just don't understand why the N* is ok in the caddy, but folks have issues between the frame rails of a Fiero. Fieroseverywhere, you said there are aftermarket parts for the 4.9. Is there a link or "recipe", for a strong daily driven 4.9? Thanks again for your input folks.

check out www.fieroaddiction.com IIRC he modded a N*, or maybe a 4.9, can't remember which. He also has info on the install. Also, google fiero 4.9 and there is links there as well for the swap. Hope this little info helps.

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Hmmmmmmmmm.......now if I can just talk the Army out of an engine, I bet I can get it to fit hehehehehehe >

Turbowedge,

You may try a search for N* install projects and a lot of your questions will be answered. The N* is 4.6L compared to the older 4.9L. I don't know much at all about the 4.9L except that everything I have read about them indicates that the owners like them. I have installed a 4.0L Aurora engine into an 88 and this engine has the same outside features as the N*. If I wanted to I could unbolt my engine and bolt in a N* with zero modifications to my original install. The N* has very large heads compared to a pushrod engine and that is where a majority of the mods come in to play. I don't know about the 4.9L fitting into the stock Fiero engine cradle but the N* has an oil cooler that gets in the way of the forward crossmember (along with the a/c compressor if you decide to use a/c). This means you have to cut out and fabricate a new crossmember several inches forward of the original. Then you can fabricate mounts after that. There is very little room left over in front and behind the engine. I think it is around an inch to an inch and a half clearance. The transmission side of the engine has a little room between the frame rail and the end of the transmission. Enough that you can slide the transmission to the left approximately 3/4ths of an inch and avoid cutting into the right side strut tower. But, if you do the install this way you have to come up with custom length axles. If you leave the transmission in its stock mounts then you have to cut into the right side strut tower about 3/4ths of an inch and this will require that you use coil-over shocks. It just depends on what you decide is right for you. I don't think you have to do any of these mods if you install a 4.9L. Someone else will need to chime in on the mods required for installing the 4.9L.

As mentioned above, either way you go, you will probably be happy with the results.

A 4.9 really moves a big ole Deville right on down the road with authority
But so does a N* with even more authority

quote Originally posted by Turbowedge: I am getting the impression from the feedback that the N* isn't really meant for a daily driver. Not saying that I will drive it everyday, ( I do have two Grand Nationals), but it will see a lot of driving time.

The N* is probably fine as a daily driver with the auto transaxle, I just would not want to drive it in traffic with a 5 speed (sometimes my 4.9 is a pain in traffic).

In analogy, if I were considering a swap for a 57 Chevy, it wouldn’t be for an engine out of a 62 Corvette. It would be for one of the more current LS series motors.
A hot rod is an old car with a modern engine. A doing a swap in an old Fiero with an almost as old Caddy engine seems to be questionably worth the trouble and becomes more questionable with every year that passes and every new engine technology that emerges. I admit that it is more affordable though.

quote Originally posted by Turbowedge: Thanks for the continued info. Is there anyone trustworthy that can build a plug-n-play harness for either option (4.9/N*), for me if I sent the original? What are the cubic inches of the N*? Is it that much bigger than the 4.9, or is it in the heads? I am getting the impression from the feedback that the N* isn't really meant for a daily driver. Not saying that I will drive it everyday, ( I do have two Grand Nationals), but it will see a lot of driving time. I want to do this swap and not have to worry with it for awhile. If it means going with a smaller engine (4.9), then I rather do that then keep wrenching on it all the time. If I wanted that, I would buy a Harley . Please no hate mail, just a joke. Just don't understand why the N* is ok in the caddy, but folks have issues between the frame rails of a Fiero. Fieroseverywhere, you said there are aftermarket parts for the 4.9. Is there a link or "recipe", for a strong daily driven 4.9? Thanks again for your input folks.

PM sent

Arn

I've driven a 4.9L Fiero and it has tons of low end torque but by 3800-4000RPM it starts gagging for air. MOST guys run mid to high 14's with it, a few run in the high 13's and ONE guy has gotten it in to the 12's with a turbo. It's a big improvement over the 2.8L, its lightweight, smooth running. low cost and it will get good mileage but this is not a racing engine by any estimation. I never claimed that its a bad engine choice, just one with severe limitations

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Turbowedge: Fieroseverywhere, you said there are aftermarket parts for the 4.9. Is there a link or "recipe", for a strong daily driven 4.9? Thanks again for your input folks.

I said there was limited aftermarket.

Delta cam will do custom regrinds... Delta Cam It appears they are upgrading their site at the moment but this is where you get a cam.

Jon @ Fieroaddiction can do a custom chip and sells bolt in mounts (and lots of other goodies). Be sure to check the Fieroaddiction informational site also. Tons of good info there.

You can also contact stickpony here on the forum (stickpony@gmail.com) who does a slightly different version of the chip supposedly using superchip fuel and timing tables. I can't notice a difference between this one and the Fieroaddiction one. I got both.

LSC performance for custom steel flywheels at a very reasonable price (in stock for 250+shipping) if you choose to go manual. 951-245-6367

Buds Outback in arizona also has some other options and at one point was working on 1.7 rockers. Don't know what ever became of that. (520) 623-8880 Tucson, AZ 85701

west coast fiero has aluminum flywheels available for a premium price. They have a few other helpful parts also. I got everything elsewhere.

Other then just a few options there isn't much out there for this engine. All of you normal hotrodding techniques still work though. I actually got quite a few of my parts at Summit Racing . Thats another good place. Hope this helps.

EDIT: Injection Technologies sells premade swap harnesses for this setup. Cost is high (~$700+) and IMO not even close to worth the money. But they are out there and if you have the money it can make for a weekend swap easily.

[This message has been edited by Fieroseverywhere (edited 01-29-2009).]

quote Originally posted by Dennis LaGrua: I've driven a 4.9L Fiero and it has tons of low end torque but by 3800-4000RPM it starts gagging for air.

I never saw this with my swap. It seemed to pull strong all the way to 5300rpm. I also converted to Carb and had True Duel Exhaust, not a Y pipe after the muffler.

quote Originally posted by Dennis LaGrua: its lightweight, smooth running. low cost and it will get good mileage but this is not a racing engine by any estimation. I never claimed that its a bad engine choice, just one with severe limitations

I don't consider it sever limitation. You work within the limits of the motor how ever I do not see it as a limit, it is far better choice then the stock motors. With your choice of words it did seem to come across as it is a bad engine to choose. Myself, I have done Two 4.9 install plus 1 for myself and looking forward to my next one.
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Found a Red 84 4speed, Waiting to get a house so I can re-home it
There are Two kinds of Fiero's : Notchies and Donors!

[This message has been edited by Kento (edited 01-29-2009).]

quote Originally posted by gem1138: In analogy, if I were considering a swap for a 57 Chevy, it wouldn’t be for an engine out of a 62 Corvette. It would be for one of the more current LS series motors. A hot rod is an old car with a modern engine. A doing a swap in an old Fiero with an almost as old Caddy engine seems to be questionably worth the trouble and becomes more questionable with every year that passes and every new engine technology that emerges. I admit that it is more affordable though.

That analogy is not quite right. If we were sitting around in 1975, the engine out of that 62 Corvette might be a good candidate for the 57 Chevy if they were plentiful for real cheap.

The 4.9 is in the sweet spot right now as being an inexpensive engine that bolts up to a FWD transmission and fits in the Fiero without any cradle or engine compartment modification.

True 10 years from now there will probably be a newer engine that's in the sweet spot, and the 4.9 considered totally obsolete. But why complain about something that hasn't happened yet?

quote Originally posted by jscott1: Dennis I agree with what you say, but with the gearing for the 6 speed, how fast do you think I'm going at 4,000 RPM? I don't know the answer, but on the street I am well north of legal speeds before the engine stops pulling hard. So the "gagging for air" comment only applies on the race track. I agree the 4.9 is NOT the best choice for a race car, but it is a very decent upgrade for the Fiero on the street.

We basically agree on all points. I happen to think that the 4.9L is a very good swap for what its does and at the price that does it. Its miles ahead of the 2.8L on power and you can swap one for about the same price as a decent 2.8L/3.1L/3.4L rebuild or longblock. It can also provide rock solid reliability. As for the parts issue, the expensive parts may never be a problem as its probably cheaper to just pop in another engine and forget about things like pistons and rods.
Yes the gagging for air comment that I made was strictly a comment that would apply on the 1/4 mile. If you think about it, the only 4.9Ls that you'll ever see at the strip are the occasional Fiero guys that run them. Putting all that aside; I agree the 4.9L is an excellent upgrade for the street and you'll be almost invincible in the 1/8 mile or in street races from stoplight to stoplight. As with any swap there are good points and bad points, so my objective is to discuss the positives and negatives without prejudice. Who knows I may end up doing a 4.9L myself one day. My yet to be finished 85 GT convertible is just crying out for a new engine and with the limted decklid venting it will probably rule out a turbo or supercharged engine. I know one guy who claims 30 HWY MPG with his 4.9L and that's a big plus for cruising.
As for the 6 speed; not having done one I cannot imagine how it will work but your top end speed is going to be quite high.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Might as well add my .02 here...
The 4.9L and 4.6L N* or even the 4.0L Aurora engines are all great choices for your swap... It's really up to your personal prefference, wrenching skills (if your doing this all yourself) and how much your ready to spend..

4.9L I would consider the first choice.. Least amount of work required, much easier to deal with electrial integration, gives great power, reliable, and cheapest of the two options.
4.6L/4.0L would be second choice, much more work involved, electronics are much more involved also, you will not be able to use the caddy PCM to run it, either a modified GM PCM from another vehicle, or an aftermarket stand alone ECU, which is what I run.. ($$$$) N* also gives you great power, maybe a touch less torque in the bottom end, but it certainly feels like it wants to keep going alot higher than a 4.9.

As far as availability, around here you can find either fairly readilly and for decent prices.. I just picked up a 4.0L Aurora engine with 75K miles for $150..

Upgradability, not too sure about the 4.9L, but speed parts for the 4.6L are not very common, and you will certainly pay a premium for them.

Daily driver concerns... While many people say the N* is not friendly enough for daily driving, I would have to dissagree, but this likely varies between car-car, owner-owner, and most importantly tuner-tuner... If you go with a modified GM PCM, unless you are well versed in tuning the maps yourself, you may end up with something that is difficult to drive.. This was the case when I purchased my car (N* swap already done), but as I am pretty good with tuning, after some work, my N* now runs like it`s still in grampa`s STS (untill your deep into the go pedal of course), and other then having WAY too tough of a clutch in it, therefore launching is a nuisance, it drives flawlessly.

As I`ve mentioned, one of my cars has the N*, and my other one will be getting either another N* or the Aurora.. No looking back from my point of view, but the 4.9L is also a great option, and quite possibly the better option for someone who is performing their first swap, and don`t want to see your car sitting on stands for years while you iron out all the quirks.... Search for northstar swap threads, and take note of the date of the first post and then the date of the post telling of the amazing first test drive... These swaps usually take alot of time.

Take these things and any other concerns you have into account, weigh your current situation (cash to spend, time to build, mechanical and tuning ability), make a decision and go for it.. Either way, in the end as long as you finish it, you`ll be happy with the results.

Hope this helps a bit...
-Jay

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87 GT Stock 2.8L 5spd
86 GT Northstar 5spd

[This message has been edited by edmjay (edited 01-29-2009).]