Turbo BS Thread

Still want to do that one someday

 

I think there was a member that was going to do it. I have not looked for updates though.

 

That's cool if you don't care about 4WD, unfortunately I do.. I'd more likely do a 4L80.

 

There's a kit to swap the 8HP65 BMW bellhousing to the 8HP75 Ram trans thus gaining you a t-case compatible flange on the rear

 

I'm just gonna get a RaptorR

 

Isn't there a super charger for the 7.3? I think those Regular cab F-250s dropped an additional 1k off added to the discount price.

 

I'm sure Whipple makes one. I can't wait to get worked by a single cab work truck on hub caps, regular Raptors got nothing for me.

 

I guess it is a whipple I thought it might have been from Ford. That would be a sight a work truck on hubcaps blowing past a gas Corvette from a stand still. I was thinking more STX on alloys but almost the same thing. I like the Raptor but for me I think appeal would ware off quick and when I went to use the bed I'd be like I could have done all of this for 30k less and not be squatting.

 

Looking to refresh or get a new head for my 3rz. Valve tolerances are stupid tight and I’m 99% sure I have an exhaust valve on the way out on #4. Looking to finally put all the turbo gear on I’ve been rat holing for close to two years now as well. I have everything I need for a low boost stock ECU setup to get me started. Really just wanting another 40-50hp for highway cruising. It would be so nice to be able to use the cruise on rolling hills doing 70-75mph. I’ve got my BT Audi for kicks.

Questions: Rework head or get a reman?
Where is a good source for valve shims?
Longevity of a w59 on say, 6psi?

 

If it's not cracked then rework it, if it is cracked you'll need a new casting, toss your old internals into that. W59 will hold anything you manage to make work with a stock ECU

 

I'd rework the stock head if possible.
I've had issues with thread pullout out of the casting on my new head I got from King cylinder heads back in like 2017.
For shims I always just order from Toyota on a case by case basis. More cost effective that way than ordering a whole kit. But you can get kits on ebay if you wanna go that way.

 

Do the RZ-FE heads have any particular tendency to crack, or is it just a general thing to look for like any other cylinder head? I ask because my turbo background is in the '80s Ford 2.3T where 90-95% of the turbo heads have cracked between the valves. It's common practice now that if the crack isn't huge and doesn't hit water, just install seat inserts and send it.

 

Yeah they're known to crack. Usually it's when people don't service the valve train every 50,000 miles like they're supposed to. And of course because it's a Toyota nobody services it so just about every use head you can buy is cracked.

 

Man, you're right, I looked up some photos and they like to crack from the exhaust seats into the plug hole and/or the intakes.

That makes me wonder if the higher EGTs and resultant exhaust valve temps of turbocharging also increases the risk of that happening.

 

I've built a couple boosted RZs, if you take care of the heads they're fine. But you let those exhaust valves tighten up from not maintaining the correct shim value, they'll crack in short order.

 

Curious how sure you are that tight exhaust vales increase the likelihood of cracked head? I can't make sense of this. The valve-seat is liquid cooled buy the head water jacket, and the valve is cooled by seating to the 'seat'. Tight valves cause burned valves, because at high temperatures they do not seat, so they loose opportunity to transfer their heat to the head, and without sealing to the seat, the edge of the valve spends more time surrounded by hot gases.I cannot picture how this influences cracking the head.

I can picture heat cycles causing cracks, with larger temperature swings being more prone. But a tight valve probably lessons the delta of the heat cycle slightly, I think. Any insight?

 

They tighten up pushing the seat farther into the head then they don't seat entirely and they burn. Only takes a few thousandths

 

Right, that makes sense, that tight valve makes the camshaft pull on the valve so hard that it mushrooms the aluminum head, at the seat insert, stressing the aluminum head and causing the crack.

(I think you were joking; or maybe you responded without much thought? Hope my sarcasm is received as light jest, to a fellow knowledgeable member.)​

Almost makes sense, except.


All joking aside, for the people in the stands: A tight valve generates LESS PRESSURE on the Valve Seat, not more. A tight valve is specifically that the gap or free-play is smaller than specified, measured from the tappet to the the camshaft, cold engine, while in the valve-closed position. This gap is to compensate for the added length of the valve stem, when heated. If the gap is too small, the valve will heat up, completely closing the gap, and then the valve is continually supported by the Valve stem, tappet and camshaft; instead of having intimate contact with the valve seat. The valve touching the seat not only seals in the combustion gasses on the combustion stroke, but the contact with the seat is also how the valve cools; transmitting its heat to the seat, and ultimately to the cooling fluid nearby. Could be said that a tight valve increases the amount of time that the valve imposes pressure on the camshaft, but 'tight' most certainly reduces the pressure or contact, on the valve seat.

BTW, The ONLY available forces that close the valve, is the Valve spring pressure, and the combustion chamber pressures. Not enough force here to move a seat or exceed the design load on the head at the seat insert. I have heard of systems where mechanical means have been used to force (pull) valves closed, combating High RPM valve float, and attempting to reduce the friction of overcoming valve spring pressures; but I personally have only heard of this in experimental applications; admittedly may exist beyond my knowing, but pretty sure these engines use valve springs.

 

An example of this in production is Ducati's desmo valvetrain.

 

Definitely caused by material fatigue from rapid heat-cycling, overheating, over designed pressures.