: supercharging a 4.6L Northstar



samm
10-30-05, 11:55 PM
can it be done?

zonie77
10-30-05, 11:58 PM
Anything can be done. Given time, manpower, money, etc...what a silly question without putting parameters on it!

davesdeville
10-31-05, 01:21 AM
Yeah it can be done, it's not impossible, it's just *almost* impossible :p The actual mounting of a centrifugal supercharger isn't too hard, it requires running a drive-shaft over to near where the stock airbox is (where the S/C is mounted.) Then intake ducting... not hard at all.

The hard thing is fuel management. The stock PCM isn't going to be able to handle boost, and anything 96 (OBDII) or newer can not be reprogrammed. 93-95s (OBDI) use a removable prom chip that can be reprogrammed, and I've heard it is possible to use an OBDI computer on a newer motor/car, however that's probably quite hard to do. Your other option for fuel management is a piggyback computer that only handles fuel requirements under boost.

XMS was going to make a S/C kit for northstars, but they dropped that idea after building one test setup when they couldn't find any way to get into the OBDII PCM.

dhs
10-31-05, 03:02 AM
Can't you send your pcm out for reprogramming? I know there was a company that would get like 50hp more out of the vw turbos and you had to send them the pcm, and that they did many other models as well. Is it just a case of a lack of aftermarket or is the cadillac pcm just so hard to modify? I remeber that some group was making a supercharger, they were even taking preorders, I wonder what happened to that.

davesdeville
10-31-05, 04:53 AM
^^ONLY 93-95s. They had a removable PROM chip. Newer PCMs have integrated memory that's nonremovable and as of now can only be tweaked with a tech 2, which nobody has and even then I'm told that can only upload new data packages (and no one has the capability to make new packages.)

Remember when you could just rejet the carb and put it on top of the blower?

Trench
11-06-05, 12:29 PM
^^ONLY 93-95s. They had a removable PROM chip. Newer PCMs have integrated memory that's nonremovable and as of now can only be tweaked with a tech 2, which nobody has and even then I'm told that can only upload new data packages (and no one has the capability to make new packages.)

Remember when you could just rejet the carb and put it on top of the blower?


Something doesn't sound right to me. But then again, that's just me.

As for OBDII, I recall seeing company's that could indeed repogram it for better performance. Fastchip is one of them. Like stated earlier, they do require you to send in your PCM, and then in turn reprogram it, then ship it on back.

They do list a few 2004 model years, too. So I know there were not a few grey area's where they can alter teh OBDII.

www.fastchip.com

Even JCWhitney sells handheld programmers for many newer model trucks that supposedly help your performance out. Many of them even have differetn programming packages for different purpose. Towing, cruising, racing, etc.

Is there something I'm not understanding? :hmm:

danbuc
11-06-05, 01:27 PM
Mark99STS seems to have been having some good results with that piggy back system he got. He's woking on a turbo setup now, but it would also work with that supercharger form XMS. This unit wasn't available when XMS developed their supercharger, so they were able to finish the project. If you could convince XMS to build you one, and then buy that piggy back setup, you could probably get it to work just fine.

samm
11-08-05, 07:33 PM
whats wrong with just buying a new high flow pump and adjustable FPR? also, would you have to alter the lines/rail at all to allow the increased flow/pressure? i really have no clue about the fuel supply capabilities in a caddy yet, so please input.
Thanks,
SAM

davesdeville
11-09-05, 04:54 AM
Even JCWhitney sells handheld programmers for many newer model trucks that supposedly help your performance out. Many of them even have differetn programming packages for different purpose. Towing, cruising, racing, etc.

Is there something I'm not understanding? :hmm:

Let us know when JC Whitney comes out with something for us. Nobody's figured out how to do N* PCMs yet, and nobody to my knowlege is working on it anymore. Sure they'll figure out crap for high volume vehicles that a lot of people will mod... but how many Caddys are there compared to mainstream cars? And how many of those are owned by old people who will never ask it for more than stock performance?

CadillacSTS42005
11-09-05, 11:51 AM
Ahh this would be a dream come true if it could be done on 96 on up caddys

Trench
11-09-05, 01:21 PM
Ah, so it is not OBDII in general. Just the Northstar PCM?

That is what I was missing.

zonie77
11-09-05, 04:00 PM
It's my understanding that low boost levels don't necessarilly need new chips. If the current program can handle the increase in flow you can run with the stock chip. You may be giving up some potential power but you'ld still have more than stock. An adjustable FPR might help.

Adding 5lbs boost may be OK. That's usually the entry level kit's output and I think many of them use stock chips on various cars.

eldorado1
11-09-05, 05:03 PM
FMUs (adjustable FPRs that increase fuel pressure in some ratio to boost, like 10:1) are typically a band aid for proper tuning. Yeah, you can probably get it done that way, but remember your injectors stop firing around 60-70psi. That means that using the stock injectors, you're good for around 3psi boost. Practically nothing... but it would be about an extra 50hp.

davesdeville
11-10-05, 03:29 AM
This got me thinking. What would happen if I just ran a set of bigger injectors off a Megasquirt, and spliced all the connections to the stock PCM. The only thing I can think of is the MAP sensor... the PCM would still see everything and I don't think it would notice that it's not running injectors anymore. What would it do if there happened to be boost in the manifold? Or if I just applied a vacuum to the map sensor all the time?

Would that make the PCM think there was either too much or too little load on the engine so tht it would shift too soon or too late? Or is that based on the TPS more than the MAP?


Ah, so it is not OBDII in general. Just the Northstar PCM?
That is what I was missing.

Well it's the OBDII N* PCM... since the OBDI N* PCM is relatively easily reprogrammed.


but remember your injectors stop firing around 60-70psi.

Why is that, exactly?

eldorado1
11-10-05, 12:33 PM
Why is that, exactly?

Because it's a solenoid. The force to open the pintle given by the electricity is a constant... The fuel pressure wants to keep the solenoid closed, and the magnetic force has to overcome the fuel pressure to open the solenoid. So once you start upping the fuel pressure, eventually it won't open anymore. In my experience that's right around 65psi on the stock northstar injectors.

I think the piggyback system is a possibility if you don't mind a few error codes and an SES light.

davesdeville
11-10-05, 03:08 PM
Yeah I worded that poorly, I understand the mechanics of an injector, I was wondering how you came up with that number.

eldorado1
11-10-05, 03:24 PM
an injector test stand. Flow was reduced above about 60-65psi, which means the injector wasn't opening all the way when it was being switched.

samm
11-17-05, 12:42 AM
here is a long shot, but... stronger solenoids? or would that be too much messin around? how about more amps to the noids? i suppose that would throw up a code, eh?

also, my question remains, could the stock fuel supply support the fuel flow and pressure increase to match lets say 10 psi from the air intake?

danbuc
11-17-05, 09:29 PM
This may be of little consequence in this matter, but I got soem interesting data two days ago form the Grand Prix GTP we have at my school. We have run it on our dyno many times for different classes and recieved pretty much the same baseline run numbers every time. Two days ago, just for the hell of it, we messed with the adjustable FPR that was on it (Series II 3800 Supercharged engine by the way) just to see what it would do. Well, just increasing the fuel pressure via the FPR alone made an extra 9-10 hp. My teacher was somewhat suprised himself by the results. With this data, I'm sure it's possible that if larger injectors were used, as well as a tuneable FPR, we might be able to compensate for 3-5psi of boost.

On a side note, the most I would ever run through a northstar would probably be a maximum of maybe 4 psi. Higher boost would result in a relative compression of more than 13:1 which would require retarding the ignition to prevent detonation. With such a high compression ratio of about 10.3:1, alot of boost isn't needed anyway.

eldorado1
11-18-05, 12:30 AM
let me guess - the series II had a smaller pulley on it, and/or otherwise was not stock.

FYI - the northstar already has an adjustable regulator.

davesdeville
11-18-05, 01:13 AM
It's vacuum referenceed but I don't think it's adjustable...

danbuc
11-18-05, 11:04 AM
No, the engine is completely stock. We have a pulley, but some idiot ordered the one for the Gen III engine, so it's not installed. The Northstar does not have an adjustable FPR. It has the same style vacuum controled FPR that pretty much every other vehicle on the road uses. AN adjustable FPR doesn't only use vacuum to control pressure. It also has shaft connected to the diaphram inside, which allows you to control the amount of fuel bleed off you have, by increasing the spring tension.

eldorado1, if you like, I can probably get a copy of the dyno run printout from the GTP. In case your wondering, we use Dynojet dynomometers at our school. They are very accurate, and never lie, unless the tach lead is fubar, in which case the tourqe reading would be off, but not hp. Other wise, whatever you do to the car will show on the dybo, which the FPR adjustment did. I was just as surpised as you are to see such a difference. I am somewhat doubtful that such an adjustment would have the same affect on a larger N/A V8 like the N*, since it has to feed two more injectors.

samm
11-18-05, 11:10 AM
uh...chuck?

samm
11-18-05, 11:16 AM
the V8 N* is naturally aspirated? what?

danbuc
11-18-05, 11:22 AM
Yes, the Northstar is naturally aspirated, unlike the 3.8L V6 that uses a Roots Style supercharger which is found int he GTP.

eldorado1
11-18-05, 11:30 AM
The Northstar does not have an adjustable FPR.

It most definately does. Notice that all of them have a security torx on the top. If you remove the little prong sticking up in the middle (break it off with a screwdriver), it becomes a regular torx. The screw is locktited in place, but once it's free, it most definately is an adjustable FPR. Trust me, I've tested it ;) Just because cadillac doesn't want you to adjust it, doesn't mean it's not adjustable ;)



eldorado1, if you like, I can probably get a copy of the dyno run printout from the GTP. In case your wondering, we use Dynojet dynomometers at our school. They are very accurate, and never lie, unless the tach lead is fubar, in which case the tourqe reading would be off, but not hp. Other wise, whatever you do to the car will show on the dybo, which the FPR adjustment did. I was just as surpised as you are to see such a difference. I am somewhat doubtful that such an adjustment would have the same affect on a larger N/A V8 like the N*, since it has to feed two more injectors.
I'd like that. I'd be interested in seeing the before wideband AFR.

danbuc
11-18-05, 05:41 PM
Sure no problem, I'll talk to my teacher on monday and ask him to get me a copy. I didn't realise that there was a security torx bolt controling a preset pressure in the stock FPR. I'll have to look at it this weekend.

Aurora40
11-19-05, 08:33 PM
They are very accurate, and never lie, unless the tach lead is fubar, in which case the tourqe reading would be off, but not hp.
Isn't that backwards about hp and torque?

danbuc
11-20-05, 02:26 PM
On the Dynojt dynomometers we have, the tach lead hookup for #1 cylinder is what provides the torque reading. I'm not exactly sure how it does it, but I guess it refferences the ignition timing relative to wheel speed and torque load on the actual drum. For a while, we didn't have a tach lead because someone forgot to remove it from the car when they pushed it out of the dyno room, which ripped the lead otu of the wall. We could only get HP numbers without it. Even on some of the cars, the spark plugs wires aren't in the greatest shape which cause spikes in the torque readings, where a Honda for example, may be making 130hp at the wheels, but the torque will be reading 400ft/lbs. This is due to the scewed data recieved from the tach lead from EFI.

samm
11-21-05, 06:36 PM
i was joking about the N* being naturally aspirated... notice i was the lad who started this thread.
in all actuality, i believe that it would be most efficient to do something other than adjusting the FPR once. i would say throw some sort of assembly attached to that torx screw to continously change the fuel pressure. it would be pointless to have the higher pressure when its not needed, like in idle or low rev conditions. you could lenghen the screw, drill a hole through it, and attach a device similar to a small engine throttle to it. perhaps activated by a small solenoid and all controlled electronically.
would it be possible to design some sort of a chip/board to change the fuel pressure proportionately to the change in intake pressure?
also, would you have to purchase an aftermarket intake pressure sensor or could you somehow tap into the existing one?
finally, my question from before remains unanswered about the fuel supply capacity/capability... meaing the lines/pump/rail... could these all handle the increased flow and pressure? i would imagine it wouldn't be that much of a change but 4 psi increase in intake would result in a needed fuel pressure increase of approximately 12 psi, am i right?

danbuc
11-22-05, 01:16 PM
well, there are a few companies out there that do have seperate FPR's that control pressure based on boost levels in the intake. Therefor, they regulate the fuel proportionly to how muhc boost is being produced. I think the STS turbo kit that's installed on the GTO that my school was using had a device like this. They did also reflash the ECM, but I think they added this seperate unit as sort of a back up I guess, since the first time they ran it, it blew up.

samm
11-22-05, 01:23 PM
yeah, i've heard of other kits doing this as well, it makes the most logical sense to me, why waste gas when you don't need to right...
STS turbo kit...hmm, you aren't holding something back from us are you danbuc? i wouldn't imagine that would be a Seville Touring Sedan turbo kit is it?

danbuc
11-22-05, 01:39 PM
Hehe...I wish. It's a Squires Turbo Systems (STS) kit that they are using. http://www.ststurbo.com/ .

eldorado1
11-22-05, 03:46 PM
I'll talk to my teacher on monday and ask him to get me a copy.
.

danbuc
11-22-05, 03:54 PM
Yeah, about that. This is gonna sound lame (I know it did when I heard it), but somebody ripped the Tach lead out of the wall again, so he couldn't use the dyno. It doesn't look like I'll be able to get a reprint of the run, since he was gonna run it again for me during his class. Of course, knowing how long it takes the damn school to do anything, it will be at least two weeks until they get a new tach leads, and I'll be back home in Jersey by then. Sorry about leaving you hangin' like that.

eldorado1
11-22-05, 05:37 PM
that's fine. Tell the guy with the GTP to fix the problem the right way. Start with replacing the o2 sensors in both banks. Old sensors can give you bad readings like that. Could also be an exhaust leak.

danbuc
11-22-05, 06:39 PM
What guy? Are you talking abotu the same GTP I'm talking about? If so, it's owned by my school, and is basically used as a guinea pig for students to see what changes in perfromance can be made by changing diffrerent variables from air, fuel,..ect.