Northstar rebuild: Will style (Page 26/119)
Will DEC 08, 09:39 PM
I'm still around... I've just been very busy and haven't been on this forum as much (62 hours on the time card so far this week).

Plans are a changin'
Money's available now and I've decided to build this engine so that I won't have a good reason later to say "well, I could have done such and such..."

[This message has been edited by Will (edited 12-08-2005).]

ryan.hess DEC 08, 09:46 PM
boost?
Will DEC 08, 11:06 PM
no...
I'll build a turbo N* after I build a 700 HP 10,500 RPM naturally aspirated VVT Northstar.

[This message has been edited by Will (edited 12-08-2005).]

ryan.hess DEC 08, 11:13 PM
switching to a 2003 block (or heads)?
Rickady88GT DEC 09, 01:00 AM

quote
Originally posted by Will:

no...
I'll build a turbo N* after I build a 700 HP 10,500 RPM naturally aspirated VVT Northstar.


Nice could you shed some light on this NA VVT? Tranny? maybe a long 6 speed?

------------------

Will DEC 09, 09:52 PM
I'm looking at Total Seal diamond lapped rings and CP pistons for the build. I wanted ceramic piston pins but HTC is having some "issues". Anyone else know about those?

Ross pistons will be for sale once I get the CP's in hand.

The VVT Northstars have the same intake ports (300+ CFM with mild porting) as the Y2K engines, except that the VVT heads have exhaust ports enlarged to match. This is enough port flow for over 700 HP N/A, and the VVT can be used to make it streetable at the same time. The potential problem with using a longitudinal engine in a transverse app is the same as for SBC... waterpump clearance. The VVT heads will require welding and machining to work with the transverse block and waterpump.

The transmission will be scratch built transverse 6 speed with sequential shifting.

Nashco DEC 12, 12:26 PM
Thanks for the update Will, as always, you've got my attention! I wish I had access to the machines you do, sounds like a fun project.

Bryce
88 GT

Will JAN 10, 04:59 PM

quote
Originally posted by Fiero STS:

Some info on N* head bolts.

Contrary to popular belief the Northstar head bolts are really not torque to yield fasteners..... The bolts will stretch very slightly (permanently) but they are good for probably 10 rundowns before any perceptable yield would occur that would render them unusable.

In fact, new bolts are run down and then loosened in the plant in the normal operation tensioning the head bolts. The pre-tensioning step actuall subjects the bolts to more tension then the final tightening step.... This is done to burnish the threads in the block as they have never seen bolts in them before the heads are installed and the head bolts tensioned. The aluminum threads need to be "worked" once before the final tensioning step so the head bolts are run down, loosened and then re-tensioned. If you started with new bolts on your reassembly then you have only done the equivalent of the first pre-tensioning step on the bolts. Use them, they will be fine. Re-using a new bolt that has been run down one time is not the same as re-using a bolt that was in the engine for 100K.......

The instructions to not reuse old head bolts is primarily because the bolts when new have a special microencapsulated coating on the threads and under the head of the bolt. The coatings act as a high pressure lubricant during tensioning and then a thread locker once installed. On a simple run down and loosening without running the engine the bolts can be "used" several times. Once the bolts see a lot of time and thermal cycling in the engine the coatings are rendered unusable again so the bolts have to be replaced as there is no repeatable means or reapplying the special coatings in the field.

If you simply installed the head with a new gasket and new bolts and pulled a timesert out and dissassembled the head the bolts are fine to use again and so is the gasket. If the head gasket was not used in the running engine and subjected to any thermal cycles it is fine. The gasket will compress permanently somewhat when torqued into place....that does not ruin it. I have seen LOTS of head gaskets run down and loosened and re-run down and continued on test fine. As long as the gasket did not stick and tear when dissassembly the gasket is perfectly fine to re-use. It has just been "pre-compressed" much as it is done in the above mentioned pre-tensioning step to condition the head bolt holes. That is done with the gasket in place so the gasket sees the compression and then relaxation in production.

With the compacted graphite gaskets it is sometimes necessary to pre-compress the gasket and even heat it during compression prior to installing it into the engine. So, simply compressing the gasket to the installed load does not hurt or ruin it. If, however, the gasket is held under load and thermal cycled in the engine it will not be reusable. That is because the thermal cycling subjects the gasket to even more load that would cause it to be deformed beyond recovery if relaxed.


At least you can reuse the new gasket and bolts with no concerns.



What's the compressed thickness of the N* head gaskets? It's close to time to tell CP what compression height I want and I would like to set quench appropriately with the stock head gaskets.

Update:
per conversation with Kevin at TS, he can get a better ring package into 3.670 bore than 3.667, so the block will be honed again... still only 0.008 over, though.

Sample stock piston is at CP for measuring. I will be going with their "X" style forging for light weight. The only number we really lack is final compression height. To set that I will need to talk to Eagle about rod stretch, get the compressed thickness for the head gaskets and take a measurement AFTER the blok is align honed and (possibly) decked of the final deak height.

Brought the block back from the machine shop. The machinist can't align hone the mains because he isn't equipped to skim a lower crank case, just main caps. I'm going to skim the lower case half, then button it back up and take it back to him for align honing.

Considering having the block decked just to be sure, although I'm reasonably confident it is not required.

Will have to take a weekend to balance the crank, and then another to assemble the engine... AFTER the pistons are ready, of course.

Might even come together some time this year.

Steven Snyder JAN 10, 05:34 PM

quote
Originally posted by Will:
Might even come together some time this year.

The Rally is at the end of April. You can do it!

86 FIERO GT JAN 10, 06:48 PM
You know, your doing so much work on this motor and what happens if it goes pop?