Northstar rebuild: Will style (Page 1/89)
Will DEC 29, 09:00 PM
I think my N* just ate a head gasket. It blows coolant out the rear bank pipe. True duals really are good for something.

Anyway, time for some engine work. Since I have to take the head off... I want to thread-sert the head bolt holes to avoid problems. Since I'm doing one side, I might as well do the other, and springs & retainers while I'm at it.

If I have the heads all the way off and the engine all the way out, I might as well do something about the oil smoke on coast down problem.

option 1: rehone and new rings. Prolly work. Boring.

option 2: mild performance build with stock replacement components. Wcapman's done one with eagle rods and I don't remember what pistons, so I can do what he's done. But who wants to do what's been done before?

option 3: exercise creativity...

I just happened to notice that DSM rods have the same pin diameter (0.866") as the N*, and the same center-center length (151 mm or 5.944"). They have a 45mm rod journal instead of a 54mm journal, however. Extra length DSM rods are available. If I offset ground the crank, I could destroke the engine to 75mm (from 84) and use 155.5mm rods. Not that it needs it, but I like short strokes. I'm kinky that way.

I also noticed that the N* rod journals are 54mm (2.126"). They could be turned down or offset ground to 2.100 in order to use 6.000" large journal Chevy rods, narrowed. Pistons would have to be custom...

How far can a N* be bored? I don't remember seeing that in the manual. I recall something about early LS1's being limited to a clean up hone but nothing else. Is the N* the same way?
If the N* can tolerate a 0.020 overbore, I could use 60 over 3.4 pistons with a relocated pin. 5mm up for stock Caddy compression height, or a little more for a 6" Chevy rod.

Jstricker: what TSB's will I need to properly overhaul a '95 engine?

Thoughts?

------------------
'87 Fiero GT: Northstar, Getrag, TGP wheels, rear sway bar, rod end links, bushings, etc.
'90 Pontiac 6000 SE AWD: Leaking ABS unit fixed, load levelling rear suspension fixed, still slow

GSXRBOBBY DEC 29, 09:33 PM
Will, Since you have helped me out in the past and I am sure I will be needing your help next month when I do the sway I will port and polish the head for free if you would like!

------------------
Bobby from NW Indiana
86 Fiero GT, Looking to ad a 93 Northstar soon

Howard_Sacks DEC 29, 11:53 PM
Blowing head gaskets suck.

You could do option four, which would be Arrow (www.arrowprecision.co.uk) will make you any rod you want so you dont have to modify DSM crap. And you can get Ti.

Then call up Mahle and tell them you want MMC pistons like they make for Ferarri. Theyll laugh at you for a bit, but eventually you will get a quote.

Seriously, if its just a head gasket, I would replace it, possibly rering the motor, and then find another block to start doing the crazy stuff to, if thats the path you want to go.

Good luck.

caddyrocket DEC 30, 12:02 AM
Sorry to hear that. I know Cadillac Hot Rod Fabricators sells the parts for a 1000hp bottom end build up and I also noticed a set of Eagle H-Beam rods on eBay for the N*. If I recall, Ross qouted me aronud 600 dollars for a set of forged northstar pistons although I have no experience with Ross. If nothing else, there is what I have off the top of my head for N* upgrades. I'm 1/2 thinking of keeping the 98 engine I have and getting brutal with it in another Fiero this summer. We'll see tho. Good Luck!
aaron88 DEC 30, 05:49 AM
I donít think boring is a good idea. The block is aluminum which means that the cylinder walls are hardened by anodizing. Anodized surfaces are much harder than steel, which is why the Northstar doesnít appear to wear on the cylinder walls (the rings wear instead). An anodized surface is typically 0.01 mm thick (thatís .0004 inches). Thereís really not a whole lot of room to play with there. Iím not saying that, that is the thickness that GM anodized to on the Northstar, but itís really hard to anodize deeper than that. Harder means more expensive and more expensive means that GM likely didnít do it. Regardless of how deep they went, were still talking one thousandth of an inch deep, tops.

Ask someone that has bored out an aluminum block before! See what the results were after a few thousand miles. Iíll bet the wrecked the motor, not that Iíd know. All I'm saying is check out the cost of anodizing those cylinder walls after you bore them out, before you decide to do it.

Aaron

.

jonmulzer DEC 30, 06:12 AM

quote
Originally posted by aaron88:

I donít think boring is a good idea. The block is aluminum which means that the cylinder walls are hardened by anodizing. Anodized surfaces are much harder than steel, which is why the Northstar doesnít appear to wear on the cylinder walls (the rings wear instead). An anodized surface is typically 0.01 mm thick (thatís .0004 inches). Thereís really not a whole lot of room to play with there. Iím not saying that, that is the thickness that GM anodized to on the Northstar, but itís really hard to anodize deeper than that. Harder means more expensive and more expensive means that GM likely didnít do it. Regardless of how deep they went, were still talking one thousandth of an inch deep, tops.

Ask someone that has bored out an aluminum block before! See what the results were after a few thousand miles. Iíll bet the wrecked the motor, not that Iíd know. All I'm saying is check out the cost of anodizing those cylinder walls after you bore them out, before you decide to do it.

Aaron

.


Aluminum blocks have steel cylinder liners. Even an anodized coating on the cylinder walls would not hold up to the wear of the piston rings.

Feel free to correct me if I am wrong though....

LS1swap DEC 30, 07:19 AM
yes they usually have steel sleeves. I don't know about the N*, but as you mentioned Will the 98 LS1 can only take a .005 hone wear as the 99+ can take .010
aaron88 DEC 30, 07:40 AM
Well; if Iím wrong then Iím wrong, what can I say. I know metallurgy, but I donít know cars.

Make no mistake thou, an anodized surface is much harder than steel. If itís not in use on the cylinder walls then it must be because the process affects the thickness of the material penetrated or because the coating isnít thick enough.

Aaron

.

[This message has been edited by aaron88 (edited 12-30-2003).]

Fiero STS DEC 30, 08:47 AM
Cylinders in the N* are steel. All of the sleeveless aluminum bores I,ve seen have been chrome plated or very high silicate aluminum ether of which cannot be bored. Will, What about an Aruora crankshaft is it the same stroke and smaller bore or a shorter stroke and same bore? Also did you ever swap ecms? or are you still running the stock ecm with the test cell chip?
vortecfiero DEC 30, 09:46 AM
1) Figure out why the head gasket went and repair it (them)
2) Do the cam and heads.... remember the N* was tuned for a very heavy car
so giveing up a bit of low end torque will gain some midrange and top end
3) unless you are adding over 50 % more hp rods are just an unecessar outlay
of cash
4) Establish a goal for your project or build up. some how this thread went fom
a discussion on mild build ups to cylinder sleaves...
5) An overbore won't add as much hp as getting more air through the engine
with intake, cam heads, exhaust and chip tuneing to take max advantage of
the new setup
5) German engines usually make 100 more hp than the N* with care and attention
to the areas in 4) and the N* is a perfect candidate
6) Supercharging or a turbo setup for 6 lbs of boost will yield far more
fun/$ and still maintain the mild personality of engine untill boost of course
7) The same cash out lay for a fart can muffler and tips probably equals a cam
and some head work

------------------
84 Fiero Turbo Vortec 4300 Phantom GT
L35 block, Syclone Intake and ECM with Moates adapter
50lb injectors, 3 bar map sens, T04B H3 Turbo www.cardomain.com/id/vortecfiero
Murphy's Constant Matter will be damaged in direct proportion to its value
Murphy's Law of Thermodynamics Things get worse under pressure.
Arthur C. Clarke "Any significantly advanced technology is indistinguishable from magic"