High Compression 3.4 DOHC (Northstar Internals)

[timg]

Nope. It's still sitting in a storage unit. I don't have a huge amount of space at home to work. I'm hoping to get it put together soon, but I have no idea when that might actually be. Over the next 2 weeks, I'll be working on a LS2 swap into my Saab 9-7X. I found a new, production LS2 for an awesome price and had to go for it. Hopefully it will be installed and running by the middle of January.

Tim

[datsun1973]

Its going to turn 5-8K RPM. I figure thats what you need to get full advantage of the DOHC heads and a short ram intake. I've seen plenty of folks chop the intake and the dyno pulls never plateau. They just run out of RPM at 7200 but the motor has more in it. I plan to run a dry sump as well so the oiling problem at high RPM is solved. The remaining issue will be valve float. I'm planning to run stiffer valve springs but I'm trying to figure out a way to do solid lifters too.

[IsaacHayes]

Damn, custom LS2 install in 2 weeks. Wish I had that kind of time/work area!

[robertisaar]

I plan to run a dry sump as well so the oiling problem at high RPM is solved.

i've never heard of someone using a dry sump in a 660 before.... could be interesting though.

[bszopi]

Kinsler and Falconer did it for years way back when. I'll have a dry sump in the stang as well.

[HayesPerformance]

I saw a 3.4 dohc with a turbo and full dry sump.

I remember seeing the engine being built it was crazy, the pan was a custom built aluminum pan....

It was built by one of our old members, he lived here in Edmonton alberta but the moved oversea's
Maybe some may remember him his name was Adrian, he use to own a very low km Indy Edition Fiero aside from the beast.

that was years ago though.....

[spearce52]

You can do solid lifters with 1978 VW Rabbit 1700CC bucket lifters and Ford Modular valves and springs I don't have part numbers with me, but I can post them later.

BMW 528 manganese bronze guides will fit if you ream the guide holes to 13 mm

You do have to trim the dia. of the valve heads a little

you need the the valves to get longer stems. Don't cut the stems untill you get the cams reground or they'll be to short


I'm doing this , not running yet
custom pistons
6.00" SBC H beam rods
2.8 crank gives 3.0L
CR is 8.3:1 for 20PSI turbo
Max torque will be around 7k max power around 9500

Steve P

[pocket-rocket]

You can do solid lifters with 1978 VW Rabbit 1700CC bucket lifters and Ford Modular valves and springs I don't have part numbers with me, but I can post them later.

BMW 528 manganese bronze guides will fit if you ream the guide holes to 13 mm

You do have to trim the dia. of the valve heads a little

you need the the valves to get longer stems. Don't cut the stems untill you get the cams reground or they'll be to short


I'm doing this , not running yet
custom pistons
6.00" SBC H beam rods
2.8 crank gives 3.0L
CR is 8.3:1 for 20PSI turbo
Max torque will be around 7k max power around 9500

Steve P

O.o That's going to be one nice screamer when it's done. Keep us posted. Thanks for the info on the bronze guides. I have a set of 96 DOHC heads I picked up this summer and sadly half of the exhaust guides have slid :/ I don't want to bolt them on until I get them fixed, too. Are you using the 91-95 style intake, or the 96-97? If you are using the earlier one, I wonder how the LIM gaskets are going to hold up to 20 psi.

[spearce52]

my motor is a 96 also, and yes the exhaust guides had slipped. When I put in the Bronze guides I machined a grove for a snap ring to ensure this doesn't happen to me.

AS for the LIM gaskets the block has been decked and heads planed to ensure a good tight fit to properly machined surfaces ( slightly rough ) to make sure the gasket is gripped

Head gaskets are custom from SCE .051" copper with ICS ( embeded steel o-ring )

Steve P

[IsaacHayes]

Do keep us posted on this. Sounds very interesting and unique!!!

[spearce52]

For Those who are interested here is my cam card from Crower

[HayesPerformance]

That info will help many...

[pocket-rocket]

When I put in the Bronze guides I machined a grove for a snap ring to ensure this doesn't happen to me.

I was wanting to do the same. Of the few sets of 96-97 heads I've seen, most all of them have this issue stock...

[Will'sFiero]

Northstar Pistons have a compression height of 1.250" with a 92mm bore (3.622").

The Northstar bore is 93 mm (3.662). My custom slugs from CP had a comp height of 1.238, but that was after having the block decked about .008 and putting them .005 in the hole.

NS pistons are forged aluminum and also already have the valve reliefs cut since they are 4V engines.

The Northstar pistons are cast. All years, bar none. GM will not allow cold start piston slap from forged pistons in their precious Cadillacs.

Valve reliefs depend on the year. '93-'95 had 1.5mm 1st & 2nd rings with 3mm oil. '96-'99 had 1.2 mm top ring, 1.5mm 2nd and 3mm oil. The '96-'99 pistons also have a narrower top ring land than the '93-'95 pistons.

The Y2K+ engines have pure flat tops with no valve reliefs and smaller pins than the '93-'99 engines.

Northstar pins in production pistons are also offset about .050.