What's up guys?
First off, I have quite a few questions, so, please bare with me. I'm considering swapping a L98 350 and 700R4 from a 90-92 donor car (once I find one) into my '90 3.1 Firebird. I've been reading all the posts for quite a few weeks now, and I just wanted to clear up some confusion and also ask a few more questions.
I'm new to the actual combo of parts inside the motor, but I tried to piece together a good street car setup (keep in mind, I have to be 100% Emissions Legal here in Chicago:

-90-92 L98 350
-Bored over .030
-LT4 Hot Cam
-Vortec Heads w/ sdpc vortec intake baseplate and EGR Kit
-24lb Holley Injectors
-Tpi Intake
-Stock Throttle Body (Or should I go aftermarket?)
-Not sure on what Headers to use (w/ EGR setup)
-Should I use the Stock Runners, or get SLP Runners?
If so, what kind?
-What type of ignition system is recommended? I was thinking an MSD Distributor w/ the Blaster SS Coil.
-I'm getting the Ram Air I hood from ASCD w/ the airbox, so, that's my induction system right there.
-I need to be able to run on 93 pump gas (not sure if this setup would alter that...or WHAT alters that for that matter. I'm guessing the compression ratio?) That would be determined on the type of pistons? What would be the best to use for what I've picked?
-I think I've covered everything, well, at least that I know of and can remember. What type of power would this give me? From the sdpc site, they were saying somewhere close to 360hp w/ just the heads and cam. True or false? What else would I gain w/ the exhaust and/or ported/polished tpi intake?
-For the Trans, I plan on just a regular rebuild (if needed) and a TransGo Reprogramming Shift Kit. Would that be the best way to go? What would be my noticable gain w/ the kit? I want to have good gas mileage (when driven normally)...but I want the ***** to really FLY when you get on it.

Now, for the swap, I know I have to do the following, and also am confused about a few things:

-Move the brake line back and move the V8 motor mounts to the front most holes on the crossmember.
-Springs are optional (v6 springs will lower front end about an inch)
-Radiator?? Some say '90 V6 will work, some say it won't. Concern about Upper Radiator hose...on the left or on the right? Will mine work?
-Fuel Pump? Will my MPFI Fuel Pump work? I heard the tpi setups give about 10 more psi. I also heard, the MPFI will work fine.
-Will my ECM work?
-I know I will have to change my PROM to a 350 chip. Will the Stock 350 chip work w/ that engine setup? Or, will I have to call Hypertech and tell them what engine setup I have for a custom chip? I'd like to get away w/ just the 350 chip I could probably swipe from the Donor Car.
-For the wiring, do I just deal w/ the part that comes out from the passenger side in the engine bay? Or, do I have to pull out the whole cable, and plug in the V8 Harness all the way back into the ECM on the Passenger Side Kick Panel? Do I have to do any other wiring other than w/ the ECM? Do I have to go under the dash on the Drivers Side for any reason? Will the ALDL work the same w/ the V8 as it did w/ the 6? I know my best bet would be to use the whole harness from the donor car. (Just clean it up, etc.) This would only consist of the Harness that plugs into the Firewall from the Passenger side? I'm not sure if a plug is there, or it just goes in the firewall and all the way to the ecm. I shouldn't need to touch any other wiring, correct?
-As for the Tach...do I have to change the wiring going up to the Gauge Cluster, or can I just change the whole Speedo/Tach cluster all together? Do I need to change it at all? Is there a way to modify the Tach w/o changing the cluster? If I need to get a new cluster, can I simply just plug it into the harness (since it is all digital anyway)? Do I need to route any new wires up there?
-Vats? Will it work? I know it has it's own box, but I'd like to get rid of it if I could. Recently, my car will randomly not want to start. I put in the key, and the starter won't even click. I can turn, and the gauges move, but no input from anything else. I have to keep the key turned, and then jump the starter right to the battery to get it to crank and start. Afterwards, I can shut the car off, and start it back up as normal. I don't get it.

At the moment, that's all the questions/concerns that I had. I might think of more, but my mind is drawing a blank at 1:15am....lol

Thank you so much for your time. I'm hoping to clear my mind of this confusion as soon as possible. Any help will be greatly appreciated.

 

C'mon guys, someone has to know a few things about this stuff.

 

ANYBODY? I'm not asking for much...just some information...I thought that's what we are suppose to do on these boards...

 

Use the stock Throttle body.

You would want shorty headers with AIR tubes. Search the Exhaust form for info on that.

Stock runners are for more torque, but SLP runners will match the rest of your engine, so go with SLP.

Their are tons of ignition choices, MSD is a great choice.

You would want a maximium of 10:5:1 compression to run on 93 octane. I would go for 10:1 though. Yes the compression ratio will determine what kind of gas you use. Pistons are one thing that effect the compression ratio. Other ppl can tell you the details on what effects c ratio.

 

Thanks TransAm12Sec!! Now, can anyone help me out w/ the wiring issues, etc. for the actual swap?

 

This webpage may help you on Wiring Diagrams.

Deadbird

The TPI forum will help out more with wiring.

 

-Move the brake line back and move the V8 motor mounts to the front most holes on the crossmember.

Correct


-Springs are optional (v6 springs will lower front end about an inch)

I left my V6 front springs in after my V8 swap at first and the car felt like it was riding the waves out on the Atlantic. Do yourself a favor and just put in a set of V8 springs up front. Eventually you are going to want to do it anyway.


-Radiator?? Some say '90 V6 will work, some say it won't.

I don't know about a 90 V6, but my 87 V6 radiator was way smaller than a V8 one. I had to replace it along with the shroud.


-Fuel Pump? Will my MPFI Fuel Pump work? I heard the tpi setups give about 10 more psi. I also heard, the MPFI will work fine.

My car was a 2.8 V6 MPFI car. I did not have to change my fuel pump.


-Will my ECM work?

I believe 90-92 (might only be 91-92) speed density V6 and TPI V8 cars used the same ECM, just a different chip. 89 and down V6 and V8 maf cars used different ECMs. Regardless you will need the V8 wiring harness, so you might as well just take the ECM, chip, and wire harness all from the same donor car.



-As for the Tach...do I have to change the wiring going up to the Gauge Cluster, or can I just change the whole Speedo/Tach cluster all together? Do I need to change it at all? Is there a way to modify the Tach w/o changing the cluster? If I need to get a new cluster, can I simply just plug it into the harness (since it is all digital anyway)? Do I need to route any new wires up there?

Just swap in a V8 tach into your cluster and you will be fine.


-Vats? Will it work? I know it has it's own box, but I'd like to get rid of it if I could.

Just have it turned off in the chip if you get one programmed. If the chip isn't looking for it then it doesn't matter if you leave all the VATS hardware in the car.

 

Thanks a lot guys for your help. For the engine part of it, was the setup I chose pretty good? Do I need to change/add anything? What would be the expected rwhp? What type of pistons should I use? For the heads, would cast iron, or aluminum be better? If it's just the weight issue, I'd go w/ Cast b/c it's cheaper. Any engine information would really help.

Thanks again.

 

The vortec heads will do you wonders for breathing on the motor (good choice). The cam seems a little big to be smog legal, but with the right tuning you may be able to keep it legal. Also the cam is a little big for just crusing gas milage, but again tune it right and it wil yeild some great results. I think over all you have a great motor that hs alot of potential. I dont recall u wanting MSD ignition but I would not fire the car back up until that is bought, and hooked up...Not only will it improve ur smog crap, it will help u squeeze that extra HP out of the car. As for power I think at the rear wheels you would be lookin at about 330-350 HP tops, but u lose like 20% through ur drive train so about +/- 400HP at the flywheel. Now these are all just guesses, but I think you would get somethin like that!! But it looks like u did ur homework now build it!! Good luck, I'm doin something similair so if u run into snags let me know so I know what to avoid!

 

FBird: If that cam is too outrageous for just street/emissions performance, what other suggestions can you give me that would keep a performance gain that the Lt4 would? I know the emissions crap really limits options, but I have to stick by them, so, what would you suggest? I also want that deep "loping" idle sound from the exhaust...I'm planning on a Flowmaster Catback from SLP Headers...so, would that do it for me? I recall the deep sounding slow lope was from a long duration cam (or something of that nature)...I could be wrong. Also, what type of pistons should I use? Should I get the cast iron Heads, or the Aluminum ones? Use the stock Crank? Basically, I'm planning on getting all the parts, and having this one guy my dad knows build the engine for me. So, w/ the right combination of things, he should just be able to bolt everything on and roll w/ it.

Thanks again!!!

 

I think that you will be able to get by with the LT4 cam, but U would have to mess with the cam timing to help benifit smog crap. If you could, could you post the specs of the LT4 cam? I have an Idea of the specs but just want to be sure...I would personally go for a TPiS cam. They are spendy but they have alot of technology into their cams to work specificly with fuel injection. I have a firend that bought one of their outragous fuel injected cams and boy, it was amazing how it worked with everything except his valve springs that broke..lol. As for pistons flat tops will do the trick! A forged crank would be the smartest way to go. Iron or Aluminum heads, if you have the extra dough by all means get the aluminum ones, otherwise the Iron ones are just as good.

 

FBird:

24502586 Hydraulic Roller (LT4 Hot Cam)

This hydraulic roller cam is for service only for all V8 engines with
roller camshafts. The duration at lash point in degrees
(intake/exhaust) is 279/287; duration at .050" tappet lift
(intake/exhaust) is 218/228; and maximum lift with 1.6 rocker ratio
(intake/exhaust) is 525/525. Valve lash is zero/zero and lobe
centerline is 112 degrees.

What do you have to do to set the Cam Timing? Something w/ the Timing Chain? Heh, forgive me w/ my somewhat limited knowledge w/ the actual terminology/etc. of the engine stuff. I'm slowly getting there though.

I also heard CompCams makes a cam close to the specs of that one...not sure what would be better.

 

Sorry dude, but if you've got full emmisions there, you aren't going anywhere with that EGR kit, injectors, and that cam.

 

Oops, sorry guys, didn't realize this post is that old!

 

IROC: What do you mean, "I'm not going anywhere w/ that EGR Kit"...etc...well, anyway, I'm having new thoughts by getting either the TPI Engine from SDPC, or maybe a ZZ4...I should be able to pass emissions w/ those using the TPI setup...correct?

 

What I mean is, since you said you have to be 100% emissions legal, then no, you can't run that sdpc baseplate/heads because you will have to get that new EGR kit, and when you get that EGR kit, it is a lot different than the stock one. You will have to put it into a header primary. Well, I don't know how different IL law is compared to CA, but here that is a big no-no. :nono:

 

Well, the stock one hooks up to the exhaust manifold stock...correct? So, hooking the EGR kit from sdpc would hook up to the headers (which is basically doing so as the exhaust manifold)...so, how would it differ? Basically, I heard here that if you have all the emissions equipment on the car, and it is functioning and isn't putting out emissions, then you will pass. We don't go through a visual here...just the sniffer.

 

Well, in that case you're fine. I was assuming you had a TPI like me, and that's a different EGR. Here in CA they are **** about EVERYTHING.