removing exhaust liners?

[lowrider]

Hello all, I’m running an F54 block and a P79 head in my turbo setup. I had an incident yesterday that involved my turbo getting jammed by a nice big piece of exhaust liner. I removed the turbo thinking that it was FUBARed. Luckily the turbo sustained no damage, luckily! So I was thinking to avoid further problems it would be a good idea to remove the exhaust liners before another one breaks and actually creates some damage. I searched and came up with nothing pertaining to the subject. Does anyone have any experience doing so?

[johnc]

Hello all, I’m running an F54 block and a P79 head in my turbo setup. I had an incident yesterday that involved my turbo getting jammed by a nice big piece of exhaust liner. I removed the turbo thinking that it was FUBARed. Luckily the turbo sustained no damage, luckily! So I was thinking to avoid further problems it would be a good idea to remove the exhaust liners before another one breaks and actually creates some damage. I searched and came up with nothing pertaining to the subject. Does anyone have any experience doing so?

 

Its a nightmare and the few who have tried gave up and sourced a different, non-liner head.

[clarkspeed]

It's not too bad, I've done it before. A hammer and sharp chisel will take them out. Once you split them, they will fold in on themselves and can be removed. Light blending required on the scratches that are left. HOWEVER, most people on this board do not recommend this procedure. You can search for the reasons.

[lowrider]

It's not too bad, I've done it before. A hammer and sharp chisel will take them out. Once you split them, they will fold in on themselves and can be removed. Light blending required on the scratches that are left. HOWEVER, most people on this board do not recommend this procedure. You can search for the reasons.

Thanks, I was kinda unsure of the removal procedure. I might just source another head as Johnc says, but at the moment im not really in the market to buy another head.

 

This motor by no means is meant to be a powerhouse. It is a budget oriented turbo venture that is planed to be replaced by a dedicated forged internal turbo motor. I just dont want to deal with the situation of an exhaust liner destroying the turbo.

[josh817]

On this board there is a thread concerning different heads and their flow. It said that if you keep the liners it makes an alright street ported head since the liners help straighten out the flow or something. May still be worth your time.

[lowrider]

I guess I'm going to try and remove the liners. Anyone done so with the head on the car? Meanwhile Ill start the search for a P90.

Edited October 11, 2010 by lowrider

[blue72]

Some reading for you:

 

http://forums.hybridz.org/index.php/topic/41824-p79-vs-p90/

http://forums.hybridz.org/index.php/topic/54639-exhaust-runners-p-79/

http://forums.hybridz.org/index.php/topic/33246-my-head-flow-work-and-graphs/

[lowrider]

Some reading for you:

 

http://forums.hybridz.org/index.php/topic/41824-p79-vs-p90/

http://forums.hybridz.org/index.php/topic/54639-exhaust-runners-p-79/

http://forums.hybridz.org/index.php/topic/33246-my-head-flow-work-and-graphs/

Thank you for the read! But nothing was particularly enlightening since I do infact know the liners did'nt hold in my case.lol

I do realize that if I remove the liners I will have to do some blending but nothing to the effect of a port and polish or major head work. Im just removing the chance for my turbine to eat another hunk of liner.

 

I don’t really want to remove the head again to remove the liners, but if it is necessary I will most likely pick up a P90. That way I don’t have to deal with the exhaust liners and it’s an excuse to practice my hand at amateur porting the P79. Either way, I would like to remove the possibility of foreign matter trying to destroy my turbo.

Edited October 11, 2010 by lowrider

[clarkspeed]

I think it would be impossible to remove them with the head still on the engine. The valves need to be removed. And you would drop metal shavings all inside the chambers if you tried.

[Tony D]

I think it would be impossible to remove them with the head still on the engine. The valves need to be removed. And you would drop metal shavings all inside the chambers if you tried.

 

 

Never say 'impossible' when dealing with mechanical items. In this same vein it would be 'impossible' to thread insert the spark plugs for the same metal-shavings reasons, or for that matter blend and match port the intake and exhaust ports with a grinding burr.

 

Both of which I have personally witnessed being done in several different ways while the engine was assembled, in the car.

 

Let your mind constrict your possibilities, and it will.

[clarkspeed]

True, nothing is impossible. How about "much more difficult, risky, and not very practical". I'm a manager in manufacturing and if I say impossible, I would get fired.

 

Funny, I match-ported an installed head last week with a vacuum and lots of balled up paper towels. No problem.

[Tony D]

Shaving Cream (Prefer Gillette Foamy) is your friend...

[HowlerMonkey]

Original poster has to ask himself why the liner got so hot that it came apart?

 

Does his exhaust have a restriction?

 

Is the timing retarded?

 

Time for an egt probe.

 

I say this because I am also running a f54 with p79 head and, even though the performance seems identical to the p90 head, I am hearing evidence of excessive heat while running low load and 4000rpms.

 

I'm going to swap the rods out for the ones with the oil squirters and see if this changes anything as well as hooking up egr since low load highway driving uses a bit of egr to keep combustion chamber temps down in the stock usage.

[Gollum]

Its a nightmare and the few who have tried gave up and sourced a different, non-liner head.

 

I don't know about everyone else in this thread, but to me this reads like John's sense of humor.

 

 

Though it's been well documented (as you've seen) the liners flow just fine. I'd never remove them as a flow issue, but you HAVE found an inherent issue with them (my very humble opinion). The NA motors will get those liners red hot, and they don't have nearly the exhaust manifold temp of a turbocharged engine. They're very thin little pieces of metal, and I think it was wise of nissan to go with a square port design without liners for the P90.

 

Take the manifolds off, be smart on how to keep shavings from falling into the engine, and go to town. Remove those suckers.

[ozconnection]

When I bought an L20AET factory turbo engine years ago, that little beauty ran a Y70 head. The Y70 head had round exhaust ports with liners.

 

Why would Nissan have chosen to use that head when the O5L and E30 two litre square port exhaust heads were also available for use?

Edited October 23, 2010 by ozconnection

[Tony D]

O5L is the turbo head. Someone mislabeled or mis-sold the Y70, it was an N/A head.

[ozconnection]

O5L is the turbo head. Someone mislabeled or mis-sold the Y70, it was an N/A head.

 

Yeah, I know that the O5L is a turbo head, but that ET engine did in fact come with a Y70 head.

 

Why would anyone have found it necessary to remove a turbo head and replace it with a N/A head? Nah, I'm confident that this was original spec from the factory from some you-beaut C211. Heavy duty rods, crank, and a factory water to oil cooler like on the LD engines convince me that it was 'heavy duty' spec. and completely original. You can tell when bolts and nuts are undone for the first time since new. (Virgins....I've had a few of them )

 

A 'sport option' from the factory perhaps? A head with 30mm intake ports instead of 28mm's, the round exhaust port issue was not a concern for the flows experienced and could in fact reduce emissions and act as an anti-reversional barrier as well.

[Tony D]

That is describing a standard N/A spec engine in several different JDM applications. That a turbo was added (all that turbo stuff is an external bolt on!) to an N/A engine should not be a surprise.

 

No Nissan Turbo Engine came with liners in the exhaust.

 

If the L20ET came with liners, why in the WORLD would they bother with the P90 or the O5L? From a corporate bookeeping standpoint that would make ABSOLUTELY no sense.

 

The ONLY reason a P90 or O5L head exists was for Turbos. Otherwise worldwide the easiest thing to do would be manufacture and stock a single universal head: the one with liners in it.

 

Beware of making assumptions that anything coming out of Japan through a used engine outlet or in a vehicle was the way it came from the "factory" unless you were the one taking delivery in person when it was new!Using your criteria, my Maxima Wagon with the L20E and Y70 Head sitting in the JY in SoCal was a factory fittment as well. Professionals doing work will leave no trace.

 

Remember I worked for an OEM (and still do in a different field...) and there are things that happen before cars are delivered (and in some cases back in a service bay while the customer waits outside due to 'insurance regulations') that would make people shudder. And from all appearances, they look "Factory Stock and Fresh" when they see them up on the rack the first service call after buying them!

 

Ever consider the reason most shops have the 'Due to Insurance Requirements we regret to inform customers that they are not allowed on the workfloor' is more with someone observing an arguable negligent act by a 'competent tradesman' which could result in far more litigation and liability down the road than any simple slip-and-fall? But I digress...

[frank280zx]

so tony why dont I Have that Y70 head in my possesion it will bump compresion!! and after some valvework.. well i want it!!

[Tony D]

Because it was some time ago that I saw it!

It was in the same yard where we got Jocamin her Antlers and you snapped the photo of the Stretch Limo, matter of fact!

The O5L is in someone's posession, though.

Brand new, bare, never been on a block, still got the part number tag on it...