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Which means "Evil Twin". Lets see your projects where you change boring into fun or create the fun from scratch.
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PostPosted: Mon Apr 20, 2020 10:41 am 
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Ahh, that makes more sense. Like you said, not cheap! So the shop used conventional machining to bore through the old bolt, then the EDM die process to cut the hex into the bottom of the stud to remove it. Awesome!

//

The '93-'99 blocks have head bolt holes that are ~3" deep with threads (well... time-serts in my old block) that start at ~1.325 deep.
These engines use 140mm head bolts and the head bolt bosses in the cylinder heads are ~3.010 tall. Head bolt thread engagement was ~1.175 or 2.7 bolt diameters.

I found out that several of the changes I was attributing to '04 actually happened for '00.

In '00, GM reworked the dies that form the sides of the block. They did not rework the valley die, the end dies or the crankcase die.
The side dies have the upper crank sensor boss, the cooling jacket drain bosses, most of the accessory mounting bosses, etc.
The side dies also define the casting features which receive the head bolt threads. Since GM updated these dies for '00, they lengthened the casting features that receive the head bolt threads. The lower/outer rows of head bolt holes in the '00-'03 blocks are ~3.800 deep overall with a starting depth of ~2.025 for the threads.

Since GM was not changing the valley die for the '00 update, they did not extend the casting features for the upper/inner rows of head bolts. However, since they were completely changing the cylinder head castings, they made the upper/inner head bolt bosses in the cylinder heads taller, up to ~3.660. The '00-'03 upper/inner head bolt threads are slightly deeper at ~1.380 starting depth.

Those changes to the block and heads let them increase the bolt length from 140mm to 156mm, though they kept the 11x1.5 thread.

For '04, GM switched to the 11x2.0 thread and further increased bolt length to 161mm. The upper/inner bolt holes couldn't go any deeper, but the threads actually go shallower at 1.150 starting depth. The lower/outer bolt holes got slightly shallower at ~3.600 with threads starting at ~1.800. Thread engagement went up to ~1.525.

LS's use multiple head bolt lengths. All are 11x2.0. <'04 engines use three different lengths, one of which is 155mm. The '05+ LS engines changed the design so that the longest bolt is 100mm.

Soo.... Where does that leave me?
I will be using Cometic MLS gaskets, so the stock torque sequence is out the window.
At Alan Johnson's suggestion, I used 70 ftlbs on my previous engine and had no problems.
I will install thread inserts no matter what.
Because I'm using '<99 cylinder heads, EITHER I'm limited to the 140mm early bolts or my current ARP 204-4204 studs in the upper/inner rows OR I need to machine spacers to use 11x2.0x161mm bolts with the shorter <'99 upper/inner head bolt bosses.

I need to measure out the 'serted and virgin hole diameters to see if the material is in the block to install the 11x1.5 inserts at the <'99 depth in the lower/outer bolt holes. That would let me run my current studs all around again.

I can install the 11x2.0 inserts all around at the '04+ block depths, and machine spacers to use the 11x2.0x161mm bolts in the upper/inner locations as noted above. I still need to figure out torque based on preload and buy a new set of head bolts (not expensive) but I would not be able to reuse my current studs :cry:

I can install the 11x2.0 inserts at the '04+ depth in the lower/outer locations. AND install the 11x1.5 inserts at the <'99 depth in the upper/inner locations. That would let me use 11x1.5x140mm bolts in the upper/inner locations and 11x2.0x161mm Northstar bolts in the lower/outer locations. I'd have to do some math to figure out the torque to get the clamp load right, using 70ftlbs on the 7/16-20 thread at the top ends of the ARP studs as the benchmark. I'll end up with different torques for each row.

If I "split the pitch" as described above I could also use ARP's 11x2.0 LS long studs--which *probably* have 7/16-20 upper threads--in the lower/outer locations... that at least means I use the same torque on both rows.

I need to call ARP about the upper thread and snagging 10 of those long studs, since I need to call them about ordering eight 11x1.5x0.880" LS flywheel bolts anyway.


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PostPosted: Fri Apr 24, 2020 10:52 am 
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mk e wrote:
, I love seeing the project, HATE your header that must be costing you 10+% of you HP but love the project.


Tough guy Mark busting on my exhaust...

The photo's dead now, but I modeled that manifold after the one this thread is about:

https://www.speed-talk.com/forum/viewto ... =15&t=8305

The biggest difference is that his short runners were angled slightly from perpendicular--maybe 10 degrees--in the direction of the log outlet. I wasn't able to do that for packaging and fab reasons, but the log shouldn't be costing me much, especially when I still have a production-based manifold on the front bank.

I have some ideas for headers, but they'll be a packaging nightmare in a Fiero engine bay.


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PostPosted: Fri Apr 24, 2020 7:53 pm 
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I wasn't trying to be mean, I was just surprised. The build it the best of everything and then is leaving 10-20% on the table by not using headers. if you want to give me detail I can model it for you and give you number to compare what you have to what you might hve if you could solve the packaging issues and get headers in there.


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PostPosted: Fri Apr 24, 2020 9:10 pm 
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mk e wrote:
I wasn't trying to be mean, I was just surprised. The build it the best of everything and then is leaving 10-20% on the table by not using headers. if you want to give me detail I can model it for you and give you number to compare what you have to what you might hve if you could solve the packaging issues and get headers in there.


No sweat, man. I know what I've gone less than 110% on in this build :P

I'm a LONG way from the engine being in a final enough form to make building headers worth the pain and downtime.

I'm still running the stock L37 Cadillac cams. Those are 266 seat-to-seat intake and 244 seat-to-seat exhaust. I have a set of CHRFab 288s on the shelf, as well as an extra set of 266s. The right 266 intake cam drops directly into the exhaust location. The left 266 intake needs to have the water pump drive parted off and the oil gallery plugged, but then it'll drop into the left exhaust location. Add a pair of CHRFab intake sprockets redrilled to advance the intake cams 10 degrees and you get the following combos that I want to try out:

266/266
266(10)/266
288/266
288(10)/266
288/288
288(10)/288

Now... Maybe modeling can help short-circuit some of that, but the model would need good head flow data, which would come from this post

TheDarkSideOfWill wrote:
mk e wrote:

I'm certain she does....she flat tomd me I'm not getting another one do this Ferrari project needs to last me the rest of my life. :?



Well darn... I wanted to work with you on porting Northstar and then cinquevalvole Ferrari heads


:lol:


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PostPosted: Fri Apr 24, 2020 10:33 pm 
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TheDarkSideOfWill wrote:

Well darn... I wanted to work with you on porting Northstar and then cinquevalvole Ferrari heads


Wait, did I ignore that ;)

How far away are you? the flow bench is just a bench these days....I could clear it for you and show you how to work and/or duplicate it.


What I do/did is pick the target first....sadly I buggered that simple math on my build because it doesn't matter if you can make 900hp of air if that means 11k rpm and 9k is pushing it. Stupid rear wheel vs crank numbers :( Anyway You pick the hp and see where you need to set the redline or pick the redline and see how much air you need then do it. Proper headers will increase the hp at any given rpm by 10-20%...or you need to spin it 10-20% higher or you leave the hp on the table.

We can model it though and look at options. If I know what size valves/port I can get pretty close to what the flow could be. Or better yet dig up what others have done...there is a website with buckets of flow data I saved somewhere....I can look if you don't have numbers others have gotten for these engines.

My cams are like 245@050 and ...270 seat duration? I doesn't take a lot and less seat duration is better for street cars. I remember reading something about the northstar having WAY too much exhaust flow, hence the short cam....the new speedtalk owner, who's a fucking trumptard so I don't visit that site anymore, was on about cams he did for an indy team years ago with short exhaust duration (using his daddy's formulas, because he's a trumptard and not in any way capable of figuring it out on his own) that helped quite a bit. The simulator will sort that out. My engine is quite sensitive to the I/E cam matching too....my exhaust flow is is a bit low (I really could use a 29mm intake vs the 28 I have) so I'm used to looking at this.


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PostPosted: Sat Apr 25, 2020 9:20 am 
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mk e wrote:


We can model it though and look at options.


I opened DM but there is no northstar base engine, we'd need to set it up from scratch so a lot of numbers I need to hunt up if you want me to do this.


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PostPosted: Sat Apr 25, 2020 11:14 am 
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What quantities is it asking for?


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PostPosted: Sat Apr 25, 2020 1:10 pm 
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Just a couple items....the images are the screen captures for my engine so you can see what goes in the boxes. Some things are easy like bore/stroke, others are really test points like the exhaust specs cause you don't normally optimize around a specific set of headers, you play with the headers looking for what works best. If there are off the shelf cams you are considering we can approximate them from the cam card spec usually. I need valve sizes....port flow would be nice but I can approximate from the valves to baseline it. Intake style/design we need but we can look at options just like with headers.

There is a simpler mode we can start of with.....but more info is always better even with that.


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PostPosted: Mon Apr 27, 2020 10:44 am 
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Ok, I'll start tabulating some of the stuff... I bet there's a Northstar file out there already.

Bore: 3.670 (3.662 (93mm) stock)
Stroke: 3.307 (84mm)
Rod: 5.945 (151mm)

Pistons have net 3.5cc DOME (along with deeper than stock valve reliefs).
I have chamber volume written down someplace and a flow sheet somewhere in my folder, although both could probably stand a refresh.
Compression should be 11.5:1.

My cam selection is limited because there are NO cores for Northstar cams; all the ones that were ever available were regrinds from the stock cams. I was looking into having CWC--the OE foundry--cast some on Proferal 55, but the price tag cam out to $20k for a run of 100 cores, and basic machining--which includes gun drilling for oil distribution--was going to run ~$100 each BEFORE they went to the cam grinder to have the lobes done. So they'd be looking at $400 each production cost. That whole thing was too rich for CHRFab's blood, so we did not move forward with it.

Nowadays... It might be good to have CWC cast individual lobes, which I could then shrink onto hollow steel or bronze bar stock. Billet steel cams are fine when used with roller lifters, but the flat tappets still last best with cast lobes. GM has been assembling roller cams, particularly for the 60 degree V6 engines, for years... Assembling a cam with cast lobes shouldn't be any different. BMW assembled the cams in the N52 engines on thin wall tube cores, then hydro-formed the tubing to expand into the lobes to lock them in place.

I know you made steel cams for your engine, but it won't see much mileage. Did you have yours DLC coated?


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PostPosted: Mon Apr 27, 2020 11:57 am 
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TheDarkSideOfWill wrote:

I know you made steel cams for your engine, but it won't see much mileage. Did you have yours DLC coated?


No.

You can have the OEM cams welded and reground, its $100/lobe late I knew.

I'll start a file....you're right someone somewhere probably has one but I don't have it so....


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