So I've got an opportunity at a 4.6L Northstar from a friend who is a mechanic. All my friends and myself are good mechanics, fabricators, electricians but throw me a bone...

How will the bell housing bolt up from an 86 2.8L 4speed Muncie to a 4.6L?

Am I in the ballpark that I think a total ECM swap is in order to the Caddy harness/ECM?

Does anyone out there flash Northstar ECMs to rid myself of the transmission controls?

Can I get prefabbed parts from someone to make this a semi painless swap?

Would anyone out there fab a northstar cradle together for me? Fieros aren't a good place to learn from mistakes...

The starter for the N* is between the heads, on top of the motor, underneath the intake. The bell housing will bolt up after clearancing the top of the bellhousing. As for trannies, I would suggest a rebuilt Getrag or the F-40 six speed, as the N* will like the gearing better on the highway. Downside to the two choices is tha the lower gears are not well matched for the torque of the N*.

Forum Member Will can flash a 7730 ECM to run the N* with a manual trans.

This is one of the more involved swaps, cradle mods, wiring, exhaust fab. Mounts are the least of your worries. ACE used to do these swaps, don't know if they are still around.

The most common way to modify the cradle for this swap has been to weld the cradle down to a flat metal table, cut out the front and rear crossmembers and weld in crossmembers made if rectangular tubing. You might find someone locally to come and do this at your build site, otherwise you need to be prepared to transport the cradle and drivetrain to and from their shop.

There are also completed N* swaps, mounted on the cradle that occasionally appear on the Forum, might be the least expensive and quickest route to success.

As for painless swap, no, don't see that. If a 3.4 pushrod swap is rated at a 3, the N* would be a 10 on a 10 point scale.

Use the search function, keep asking questions, and plan, plan, plan.

And remember, if you think you can do the swap for $1000, better have $4000 available. Realisticly, plan for $6000.

A few questions......

What year N*?
How many miles on the motor?
Condition of the Motor?
Why does the mechanic have the motor?
What VIN # (Y or 9) motor?
Do you have welding and fabrication experience?
Can you weld exhaust tubing?
How long can your car be off of the road?
How big an area do you have to do the swap in?
How long do you have access to the shop?
What all tools do you have access to?
Do you have a very good idea of how a modern fuel-injected compuerized engine is controlled?
Do you have the skills to troubleshoot and correct the issues you may encounter after initial start-up?

I am sure others will chime in. I hope that this reply will help you address some of the considerations involved in this swap.

By the way, I think the perfect swap for a Fiero is a manual trans N*. I have plans to do the same thing to my 86 SE. I have already upgraded the brakes, suspension, hydraulic systems, and have collected everything else, except for the motor, flywheel and clutch. I will be using an 88 rear cradle, Getrag, and am striving for 450 HP out of the motor.

Good luck with this project. Planning beforehand is your best guarantee for success.

Joe

[This message has been edited by olejoedad (edited 02-28-2010).]

Olejodad, Ryan Hess is actualy the one who has the 7730 ECM programing.
This is a good system, I will be using it on my own swap, however it only works on 96-99 engines.
You might want to enquire as to the history of the engine you are considering, the northstars have a history of head gasket problems. (not a cheap repair)
Link: https://www.fiero.nl/forum/Forum2/HTML/070626.html
As mentioned above, the bellhousing of the transmission will need to be clearanced for the starter. Also, a small adaptor is required for one of the bellhousing bolts. For a flywheel, you will have to use a modified 88 5 speed flywheel or buy an aluminum one from spec. CHRFab also sells a flywheel, but it is for a rearwheel drive application and will need to be modified. No one sells mounts for this swap, so you are stuck with making your own. The stock trans mounts can be used, but I would highly suggest using poly replacements.
Fuel pump must be changed, a pump for an early 90's vette is a direct replacemnt and will provide enought flow.
As said above, use the search, it should give you a pretty good idea about what's involved.
Remember for each swap, there are tons of little things that have to be done for it to work right.
If you have limited time/skill/facilities, you might be better off buying one already done.

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* 97 Olds Cutlass DD
* 86 Mustang SVO Rear Ended, R.I.P

* 86 Fiero GT, Soon to be Northstar

As stated theres a bunch of build threads floating around now with Northstar info, lots of good knowledge if you take the time to look..

Although im not saying its possible or been done, I can't find any info regarding any swaps using the muncie 4 speed, and will echo the reccomendation to find a getrag 5 spd or go to an auto. There are a number of different swaps out there using the getrag with the required modifications detailed well.

Something else to keep in mind here, custom flywheel and clutch components will be required, SPEC clutches has in stock many different clutch combinations designed for the N*/getrag swap, I am unsure if they have products for a N*/muncie swap. They also sell aluminum flywheels for the getrag application.

The northstar pcm's are one of the few GM ecu's that have not been sucessfully hacked. Go with with the 7730 ecm or you will will be looking at an aftermarket controller such as the Holly Commander 950. 7730 would be the easiest and likely most cost efficient, but an aftermarket ecm will let you create/adjust the tune yourself if you are so inclined.

There is likely very little to no prefabed parts available, a N* swap is fabrication intensive.

Unless someone chimes in offering to build or sell you a modified cradle, get yourself a spare one and start fabricating. Once again, if you go with a getrag there are a number of threads out there which will lead you through the cradle modifications.

- Jay

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

I have a Northstar project, long in the works. I would like to see more Northstar swaps but I wouldn't recommend it unless you are committed to a large investment of time, research and funds. It is not such a simple swap. Chevy V8 or 3800 SC is very well documented and it is proven reliable. I think you need good reason to do a Northstar.

quote Originally posted by rourke_87_T-Top: I think you need good reason to do a Northstar.

Although it is becoming more common, I still like to think of it as a unique/rare swap.

IMO very few swaps out there have the same cool factor as an all aluminum 32v V8. If GM was still building mid engine 2 seaters, I think the N* would have been a great offering for GT versions.

- Jay

Hey thanks for all the info guys! I listening to every bit of it. On the other hand this is going to be more of a daily driver/sleeper not a drag car. Sounds like a 7730 ecm is the way to go. The engine will either be a 96 or a 99. One just had the head gaskets done, the other will have them done before installation. The 96 got wrecked about a year after head gaskets. Looks like the 96 engine is going in the 99 STS so the 99 STS motor is probably going to be mine. A hair over 100K and it'll be a fresh top end. I doubt I'm going with anything but the Muncie 4 speed that is in the car. I don't like the 282s and I'm not an automatic man. If it's going to be a pain in the butt either way might as well deal with a transmission that I know is good and I like. If I have to modify a flywheel sobeit. My plan right now is to keep the cradle out of the 96 Caddy and hermaphrodite the two into one. I think the rear bumper is coming off the car tomorrow so I can lube the cradle bolts. I'm totally ready!

[This message has been edited by FieroBrad87 (edited 02-28-2010).]

Thanks for the additional input and corrections to my post.

As stated in the additional posts, it's very easy to get in way deep, and find out you are not as good a swimmer as you thought.

Also, you can save yourself some time, the back bumper doesn't need to be removed to soak down the rear cradle bolts. Get it up in the air and squirt in through the triangular cutouts in the lower frame rail to hit the top threads on the bolt.

Another tip, when you drop the cradle, bring everything out of the driver's wheelwell, as it saves about a foot of lifting height.

Good luck and keep us posted.

I'm pretty sure that the 4 speed has a problem with linkage clearance. I think that there was a member GXR Robby or something like that who started his swap with the intention of keeping his 4 speed and then switched to something else.

It is probably easier to just modify the Fiero cradle than to mesh the two of them together unless you plan on retaining the 4t80 auto. If you use trans mounts in the stock location, at least for a getrag, the modification to the cradle is pretty straight forward. If you lack a welder, you could even cut the pieces yourself and then take it to a shop to be welded.
Good luck!

I could make a N* cradle for you. You can come over and check mine out sometime if you want. It mainly involves relocating the front crossmember farther forward

[This message has been edited by Erik (edited 02-28-2010).]

I don't know where the clutch slave is on the 4-speed but you might find it easier to modify the release arm and use a pull slave if it happens to run into the N* water-log. example

Charlie

[This message has been edited by cptsnoopy (edited 03-01-2010).]

Thanks again dudes...

Erik may come in very handy. I've seen his N* cradle, very nice.

Are the 4.9s and 4.6s essentially the same mounting points?

Let me tell you a lot of brainstorming went on Sunday between my friends and I.

Looks like I'm getting the '99 engine which is nice because it has almost the same exact miles as my car. The head gaskets will need to be done on it but I'm going to be at the grindstone to finish college in May so the timing will work out.

quote Originally posted by FieroBrad87: Thanks again dudes... Erik may come in very handy. I've seen his N* cradle, very nice. Are the 4.9s and 4.6s essentially the same mounting points? Let me tell you a lot of brainstorming went on Sunday between my friends and I. Looks like I'm getting the '99 engine which is nice because it has almost the same exact miles as my car. The head gaskets will need to be done on it but I'm going to be at the grindstone to finish college in May so the timing will work out.

If you need it timeserted I have the kit, you would just need to buy the serts

I would not put the heads back on a N* without timeserting it. If for no other reason than feeling more secure with the engine.

[This message has been edited by dratts (edited 03-01-2010).]

Yes, defenitely put an insert approach in your block if its an early 94-99. I'm using Norm's inserts off of ebay with ARP head studs. Others are using Jake's one-piece studs made specifically for the Northstars. I would also suggest using the Cometic gaskets that are available so your original GM style graphite gaskets will not shrivel up around the water jacketed areas like they tend to do after 50K miles. These two alterations are really long term life insurance for maintenance on your motor.

There are a lot more options now with regard to the PCM approach. You have Westers Garage up in Canada doing stand alone programming for the Northstar, the Holley Commander, Haltech E6K (or similar), 7730, Megasquirt, and the LS1 PCM that I'm currently working bugs out with my programmer for my application.

Everyone seems to be doing this swap a little bit different from a fabrication, PCM and modification standpoint.

Another thing about the Northstar flywheels. I sorta regret going with the Aluminum flywheel with the steel insert because of the clutch size restriction. I would prefer the all steel flywheel so you have the option to run the 9 11/16 clutch. I don't think anyone is making an aluminum flywheel with a larger steel insert.

The HP and RPM capability of this engine is truly incredible with a little modification with valve springs, cams and other add-ons.

Be prepared to save and spend more money and take more time than you had originally anticipated.

[This message has been edited by IXSLR8 (edited 03-01-2010).]

quote Originally posted by FieroBrad87: Thanks again dudes... Erik may come in very handy. I've seen his N* cradle, very nice. Are the 4.9s and 4.6s essentially the same mounting points?

You cannot use the 4.9 mounts for a northstar swap. I am not sure how similar their mounts are, but making custom ones isn't very difficult.

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* 97 Olds Cutlass DD
* 86 Mustang SVO Rear Ended, R.I.P

* 86 Fiero GT, Soon to be Northstar

I need to run the engine AND transmission with a PCM of some sort... I hadn't thought about a 7730 being an OBDI. Since I hear so much about 7730 upgrades I figured you guys were upgrading to OBDII. Obviously an OBDI of any kind isn't going to do anything for a 4t80e.

I've given up on the manual transmission plan. That's way too much fabricating to be reliable. So flywheel concerns and gone. I'm not going to have much time between now and the middle of May to do anything myself. The engine will probably get fixed by someone else. I'm just trying to line things up so I can bolt this stuff together after graduation with little or no struggle. The I'll worry more about wiring it. I'd like to just use the PCM that's in the Caddy. I don't know why that would be a problem but...

[This message has been edited by FieroBrad87 (edited 03-02-2010).]

quote Originally posted by FieroBrad87: I need to run the engine AND transmission with a PCM of some sort... I hadn't thought about a 7730 being an OBDI. Since I hear so much about 7730 upgrades I figured you guys were upgrading to OBDII. Obviously an OBDI of any kind isn't going to do anything for a 4t80e. I've given up on the manual transmission plan. That's way too much fabricating to be reliable. So flywheel concerns and gone. I'm not going to have much time between now and the middle of May to do anything myself. The engine will probably get fixed by someone else. I'm just trying to line things up so I can bolt this stuff together after graduation with little or no struggle. The I'll worry more about wiring it. I'd like to just use the PCM that's in the Caddy. I don't know why that would be a problem but...

Brad you can run a 4t60e with the 7730 and ryans tune for a stock 300hp N. ( edit I checked and found out that ryans tune doesnt support the 4t80-e or 4t60-e) The problem with the stock OBD2 caddy PCM is that it will need all the peripherals like the caddy BCM and the caddy DIC hooked up or it will not work right and go into limp mode and second gear start. I seems I have heard of a tune for it though that could eliminate the perhepherals but not sure. The 7730 is the most cost effective setup but of course that is if you want to use the 4t60-e with it. You could get a separate trans controller for the 4t80 e but ..there are + and -s to using each

[This message has been edited by Erik (edited 03-02-2010).]

quote Originally posted by Erik: Brad you can run a 4t60e with the 7730 and ryans tune for a stock 300hp N. The problem with the stock OBD2 caddy PCM is that it will need all the peripherals like the caddy BCM and the caddy DIC hooked up or it will not work right and go into limp mode and second gear start. I seems I have heard of a tune for it though that could eliminate the perhepherals but not sure. The 7730 is the most cost effective setup but of course that is if you want to use the 4t60-e with it. You could get a separate trans controller for the 4t80 e but ..there are + and -s to using each

So I should go with a non electronic shift tranmission? What is "ryans tune"? I don't understand how any OBDI can run a transmission.

quote Originally posted by FieroBrad87: So I should go with a non electronic shift tranmission? What is "ryans tune"? I don't understand how any OBDI can run a transmission.

I went and double checked and it appears ryan doesnt have a tune for an auto with the 7730. You could use the 4t60 non electronic trans

I'm ok with a non-electronic transmission. I really don't even need a four speed with that much power.

Here is another option but expensive http://www.powertraincontro...com/transcontrol.php

At that point it appears the stock OBDII caddy PCM would be the best solution if you can get it tuned to disable the requirement for the BCM and the DIC

Actually I'm totally cool with a 7730 and a non-electronic automatic. I'd even been cool with a TH125. Simple equals Light, right? Plus the oem shifter isn't going to be as friendly to a tranny with an extra gear.

quote Originally posted by FieroBrad87: Actually I'm totally cool with a 7730 and a non-electronic automatic. I'd even been cool with a TH125. Simple equals Light, right? Plus the oem shifter isn't going to be as friendly to a tranny with an extra gear.

the TH125 wouldnt last long with a 300 ft lbs of torque ..You have the choice of a 4t40 or 4t60 with the 4t60 being stronger. They used the 4t60 e with the caddy 4.9 which puts out 280 lbs of torque so you should be ok with the non electronic version of that trans

So I'm looking for a 4t60 then...

quote Originally posted by IXSLR8: ... LS1 PCM that I'm currently working bugs out with my programmer for my application.

Not to rob the thread, but I've been contemplating this for awhile. What OS are you running, and do you have a copy of the .bin file? I'm considering a Moates Roadrunner if an OS is compatible with an '0411. A forum member whom I don't care to mention has talked with me several times about this setup, but his answers to my questions are like watching the TV show Lost. I've since given up trying to get any information out of him. I want to run a Roadrunner, I just need a Monodax/TunerCat-compatible .bin. Any ideas?

The 4T60 or TH125 torque converter has a three lug design, The Northstar has a 4 lug design. The flexplate will not bolt direct to the torque converter. The 4.9 flexplate will not bolt to the Northstar crank, 8 bolt. The Northstar flexplate will clear the inside of the bellhousing and there is enough room for the starter to fit inside the top of the bellhousing, I am doing a Northstar swap using the 1991 Allante high strength 4T60 model 1KZH, I ordered a custom torque converter with a 2500 stall speed from chrfab.com other members on here have used LT1 with a 4T60.

quote Originally posted by rourke_87_T-Top: The 4T60 or TH125 torque converter has a three lug design, The Northstar has a 4 lug design. The flexplate will not bolt direct to the torque converter. The 4.9 flexplate will not bolt to the Northstar crank, 8 bolt. The Northstar flexplate will clear the inside of the bellhousing and there is enough room for the starter to fit inside the top of the bellhousing, I am doing a Northstar swap using the 1991 Allante high strength 4T60 model 1KZH, I ordered a custom torque converter with a 2500 stall speed from chrfab.com other members on here have used LT1 with a 4T60.

I don't want a stall converter but that is great information, exactly why I started my own thread for this.

So are you saying that the flexplate and torque converter from a 4.6L/4t80e won't fit into a 4t60?

They will not bolt up without a custom torque converter, that is a $850.00 expense for the modified 10" 27 spline with .824 pilot.

[This message has been edited by rourke_87_T-Top (edited 03-02-2010).]

quote Originally posted by rourke_87_T-Top: They will not bolt up without a custom torque converter, that is a $850.00 expense for the modified 10" 27 spline with .824 pilot.

Why not a custom flex plate? I may sound like an idiot but why not drill the flexplate to fit the TC?

I don't think that would work, I'm not saying it couldn't be done but modifying the flexplate would be quite an accomplishment, I wouldn't want to be sitting in the car if it ever came apart at +6,750 - + 8,200 rpm's , it would cut your car in half lengthwise like a sawblade. The larger 4T80 torque converter has 30 spline and will not work either. In case you get that idea.

[This message has been edited by rourke_87_T-Top (edited 03-02-2010).]

quote Originally posted by rourke_87_T-Top: I don't think that would work, I'm not saying it couldn't be done but modifying the flexplate would be quite an accomplishment. The larger 4T80 torque converter has 30 spline and will not work either. In case you get that idea.

Well, good info none the less. Not a good way to start the day though.

It's better to know now before you start buying motor and tranny. I can't even tell you that it would work anyway, as far as I know I'm the only one doing this combination. I have not seen a Northstar with a 4T60.

Are you sure about Ryans 7730? I could swear that his car has a 4t80e with tap shift in it. My N* was installed by a caddy mechanic in NC and uses the th125, It has a recepticle to plug in the caddy instrument panel on the passenger side.

Ok well NorthStar 4.6L and a 7730 ECM. I just can get the power to the wheels so far. Maybe fabbing a manual into it ISN'T the worst possible idea.