: 4.6 Northstar Engine mod question.

Lac' Lo'
04-12-04, 11:52 AM
Im wondering as to what extent is the 4.6L v8 northstar engine modifiable.

If im not mistaken it gets 270hp stock, But what all to the engine could be done that would give it substantial hp increase.

I plan on getting headrest screens,visor tv screens,two 12" subs/w two amps for the interior....

But im wondering about a couple things as im not that experianced with knowing about different engines and what can be done and id like to clear up some things today with a few questions.

After market Cold Air exhaust would fit right? im not sure if you can put them on all cars..

after market headers... Can these be installed?

And the most important question was boreing the engine some one told me this would increase the hp greatly since they cant sell them with big bore sizes for emmision purposes..Wouldnt the engine block need to be taken out and apart for this? how much would this cost? and is my friend telling the truth about the bore size thing?

im not trying to turn this into a racing machine because this is a heavy car... and big...

oh BTW does the '94 cadillac devilles have goveners... if so isnt there chips to overide the govener?

-- Paul

04-12-04, 05:56 PM
The rated power of the northstar varies by year. First off, are you sure you have a northstar? Cause only the DeVille Concourse had the northstar in 94.

There's no such thing as "cold air exhaust," there are, however, cold air intakes. These can be worth some extra power depending on how restrictive the stock intake is, I don't know on the northstar if it's worth the effort.

I haven't heard much of boring the northstar, but I imagine if it's possible it would be a pain in the ass because of the electronics.

You might look into a nitrous system, you can probably safely run a 100 shot, I know iceheart has NOS. Forget what his name is on this site. Shadow something.

04-12-04, 07:25 PM
Phil, the guy Dave is referring to is SHADOWLVR400 on this forum.....

Agreed with what dave said, the intake on the northstar is VERY low restriction, so sticking with your stock filters and setup will be the overall best bet...

You CAN NOT bore out a northstar due to the cylinder liners (cast iron liners in the aluminum block).....

There isnt a lot for the northstar, check out www.chrfab.com and they sell some stuff for the northstar.....

05-01-16, 11:07 AM
Just want to let you know I know someone who rebuilt his 4.6 north star he had it bored 0.010 over. Changed intake cams and larger injectors . picked IP about 30 HP. Not worth the bother I think.

05-01-16, 11:19 AM
12 year old dead thread did up... Wow that may be close to a record right there.
I could pick up that much HP by cleaning the shit out of my trunk...

05-01-16, 02:02 PM
Old thread, but - if you were to change the VIN Y cams for VIN 9 and do both a PCM change and final drive change to correspond with the VIN 9 requirements you would, in fact, pick up "about 30 hp" - as in: from the 275 hp VIN Y specs to the 300 hp VIN 9 specs.

Who did the PCM/ECM reflash (pre-1998) to compensate for the new fuel flow rates ?

The aftermarket pistons and rings, if used, had about nothing and zippo to do with the hp increase........ and the old info in here still stands: GM does NOT recommend overboring the Northstar due to its thin walled cylinder sleeves. The later supercharged Northstars were reduced to 4.4 liters by thickening the sleeves for just that reason.

Does your friend have the before and after dyno sheets ? ......."about 30 hp" means nothing without accurate before and after comparisons.