The engine is at least twice as easy to work on outside of the car. That being said I would make sure you have exhausted all other in car possibilities before pulling it.

Haven't done much to the car lately. Kind of recharging my batteries and working on a mini-chopper bicycle for my daughter.

I did do another compression test to check the cylinder that was dead before. Came back 135-135-140-140 where the previous check was 142-130-0-140. Kind of strange that one cylinder dropped and another picked up compression.

Hopefully I'll start pulling it apart this week. I'd like to get it out before the temps drop too much.

I did see this interesting post on tuners Intake Manifold

Trying to add up material cost and see if it's alot cheaper that buying one. I've got a friend with a TIG and and oven to heat the aluminum. I doubt it would help a 14b setup, but should be good to a 16G upgrade or bigger

Here's something I've been working on. My ProE skills are rusty but it's getting there. If I can manage to get some after hours CFD done at work I might take a look at it.

Been researching the internet for recommended plenum volume and runners length.

Manifold 1

Manifold 2

I know it's easier to buy an intake, but I may be able to build one for $200. It might not be as good as a big name intake but I figure with a little research it should be better than stock.

Drooool... ProE pictures...

Sorry... I'm a nerd.

I like the slight taper on the runners from circular to ellipsoidal.

Would that increase flow because it's somewhat divergant? or does that matter? I'm not an ME and I didn't enjoy fluid mechanics much

I have a JMF intake with a melted corner from the fire. Maybe you could take all the measurements off it you want in return for cutting out the 'melted' part and welding in a section of sheet for me?

Wort
I don't necessarily want to copy a design. But I am curious to look at existing design Plenum and runner lengths as well as the ration of their volumes. These dictate what rpm band the engine makes it's power.

Send me a picture of the melted intake. I'll talk to my buddy that does the aluminum welding.

Jbone
The flow shouldn't increase because the cross sectional area is the same. If it was a true taper like I've seen on some intakes, it would change the flow.

From what I'm reading....and my head hurts now...

Tapering the runners increases velocity (venturi effect) which seems not to be affect by a forced induction setup. But too much velocity isn't a good thing, <75 m/s is recommended by one source

Longer the runner, the better the low end torque
Shorter runners push the hp peak higher in the rpm range
5-6" runners seem to be the sweet spot for street manifold

Plenum volume also affects the HP peak
-Larger the plenum, the higher the HP peak and low end response suffers. Running a huge plenum on a car that spend most of it's time in th 5-6K range is useless. I've read estimates of plenum volume 10% more than engine CID to 2 1/2 times the volume of the 4 runners.
-Bellmouths inside the plenum are highly recommended.

My rambling only hope to stir conversation...I stayed at a Holiday Inn Express last night and now I design manifolds!

Finally got the engine apart Sunday. The head gasket was correct and had the teardrop cutout in the front left stud position. Spinning the oil pump with a drill resulted in a 1-2' fountain of oil coming out of the hole in the top of the block. So the pump in good and the block passages are clear.

The head passages are clear. So the only thing different is the ARP studs....

I'm going to try lightly bolting down the head with the old gasket and put the stock head bolts back and see if the oil start flowing.

I can't think of anything else, yet why the hell would the studs cause that???

After installing the rebuilt head. The oil pressure gauge always showed normal pressures. 100 psi when cold, 50-75 cruising down the road. I don't remember exactly but i don't think it ever dropped down to 10-15 at idle through.

With the engine warm and idling, there was no oil flow out of the banjo bolt hole when removed.

There wasn't much, if any flow to the head since the moly lube was still on the ARP head stud nuts after the engine ran for 15-20 min while diagnosing the no boost problem....which turned out to be the turbo eating itself due to no oil flow.

The oil pump was brand new, new case and gear when the engine was rebuilt in 4/06. I guess it could have injested something...

Hopefully I'll bolt the head back on with the stock bolts tomorrow and at least eliminate that possible option. I need to drop the pan and check for any obvious damage.

Blew shop air through them after removing the turbo supply and then the galley plugs above the head/block connection. Air/oil came out through the lifers.

I imagine the galley could be partially blocked, but there would still be more than a dribble flowing.

Well it looks like the ARP studs is the cause.

I mounted the head with the stock bolts torqued to 40 ft'lbs so the oil wouldn't squirt out between the head and the block. Spun the oil pump with cordless drill and oil streamed out of the turbo feed hole and out of the lifters.

I swapped the head bolt that's in the oiling path to the head or a ARP stud, and....just a dribble of oil out the turbo feed and no oil flowing out the lifters!!!

WTF!

I measured the diameter of the fasteners:
ARP studs .469"
Stock head bolts varyed between .436 and .442"

The increase in OD of the ARP studs reduce the available flow cross section but why would I be the only one in history to have this problem???

Almost sounds like you got the wrong studs. I'd call ARP and ask them what their measurement specs are for the studs and see if they match what you have.

I'm pretty sure that the ARP studs I have are larger in diameter than the original bolts. Maybe the head casting is a little off or there is some build-up of some sort in the oil galley?

I'm going to call ARP tomorrow, it can't hurt.

The head passages are clean. I checked.

I'll try measuring the head passage opening after I pull it off again and compare the measurments to the old head (.550") I have.

Thanks for the ideas guys!

Hey Marcus...who did your SIG picture. Pretty slick!

FoxEm on CSS did it... They've got a sig thread going where they are using their creativeness to help everyone out.

they do good work too

Can anybody verfiy what is the correct stud kit for a 92 6 bolt? I mean what they actually used and didn't have a problem with.

I called ARP and explained the whole story and they recommended the undercut studs to allow for the oil flow...but their own catalog says the undercut is to "equalize the stretch of the bolts" not for oil flow. The guy sounded like he was fishing...not a great tech call. He asked who sold them, I said a local machine shop, he said you should have called us...

Their catalog states for 93 and earlier m12
207-4201 12 pt nuts (what I have)
207-4701 12 pt nuts with u/c studs

Mine were not undercut.

I've used three sets of standard cut ARP's without issue as well, very strange. How did the measurement compare?

Looks like I solved the mystery. The new head's head bolts holes are drilled undersize (around .473). On the old head a 1/2" drill bit will pass through all holes. On the new head, only 1 bolt hole will pass a 1/2" drill bit! The stud where the oil flows though is counterdrilled to .550 the same on both heads but the hole is too tight where the cross drilled galley intersects.

New head, you can see the ridge:


Old head, minimal ridge:


This would explain the lack of oil flow, I've got a .469 head stud in a .473 hole!! Not much flow going through that.

This would also explain why the head was so hard to put on!! Almost no clearance.

I'll call Mullvains to see how much they charge to drill out the holes. I'm not sure I could accurately drill them out with a cordless. I need to first check the cam bearing clearance and make sure the lack of oil didn't FUBAR the head.

I can't beleive the manufacturing process would be this far off.

Wow...That took some detective work. Good find Chris.

Is there any chance this is something other than a turbo head? Not sure if there is any good explanation for the smaller holes?

Is it a 1G 7-bolt head? They have smaller bolt holes.

I thought 7 bolt heads had different port sizes? Still strange that one head bolt hole in the head was the correct size.

What are the differances between the 6 and 7 Bolt heads?

I think its just the 2G heads that have the smaller intake ports.

Mullvains will drill out the holes, by their hourly rate ($50). They said they'd have to look at the head to give me an estimate.

I guess I'll have them check the head for flatness. I can't imagine it's warped from just a couple heat cycles....