Change headgasket and studs, or leave it as it is? + some more Q's

[pjo046]

The 280ZX Turbo-engine I have bought(It's on it's way to Norway, haven't received it yet), has 51 000 miles on it. Should I change the headgasket to a 1mm steel one, and install ARP Head studs, and at the same time resurface the block and head? Or isn't this really necessary, so if I'm budget minded I can just drop doing this? It will cost a bit to do it in parts and labour, and I'm running out of funds.

 

Does the 280ZX' have 5 or 6 digit trip-counters on the speedometer? If it has 5 like the earlier Z's, then I can't be sure of the mileage really being 51 000. So if so, I guess I should change the headgasket and install studs, because then I can at the same time inspect the pistons etc... But if it has 6 digits, and thus the engine has really run 51 000 miles, then it shouldn't be necessary?

 

I'm shooting for 350hp at the wheels. Can the stock headgasket and bolts cope with such power reliably? And how about the stock ZXT clutch? Will this hold up? If not, anyone has any cheap alternatives? Is a lighter flywheel a waste of money?

 

I will install 4-piston calipers up front, and ferrodo brake shoes at the rear in the 240Z this engine is going into. Will the stock 71 brake booster etc do, or do I need to swap it with 280ZXT versions?

[Clifton]

The stock HG and bolts are fine. That's what I run in mine.

[pjo046]

Anyone else has any input on this? And on the other questions?

[Cody 82 ZXT]

I agree the stock gasket holds up well unless you get into some detionation then just about any gasket would blow(or kill pistons).

 

Lighter flywheels seems to be a good mod. I have a stock lightened flywheel on my ZX.

 

Don't have a good source for cheap (good) clutches anymore. The site I bought mine from is no longer offering the setup that I have. Take a look here and see what ya think. Sseveral members run these clutches.

http://www.specclutch.com/specMain.html

 

ZX's came with both the 5 and 6 digit style speedometers.

[pjo046]

This engine is out of a 1981 280ZXT. Does that mean it's a 5 digit one then? So I can't be sure of the mileage?

But anyhow you think I can just leave it as is, and concentrate on removing A/C, mechanical fan, port the manifolds, smooth out the inlet manifold, ceramic coat the exhaust manifold, and let that be it? And spend the rest of the money on engine management, turbo, driveline, suspension and brakes?

[Clifton]

If it's not broke don't fix it. I made over 400 rwhp on an unknown junk yard L28 and 400 on a 7M with 180K miles, I know others have made alot on high mileage motors too. Ceramic coating IMO is a waste of money. It looks nice though. Did decide on your turbo specs yet?

[z-ya]

I'd do a compression check, and if it looks OK drop it in and run it. If the compression looks questionable, pop the head, and put in a fresh Nissan gasket. You can use the stock head bolts again too. To use a metal gasket, the two mating surfaces need to be perfect, or it will leak. If you plan on running less than 15psi, stick with the stock gasket. Another option is to use copper O-rings with a stock gasket. You will need to have grooves cut in the head for them though. I'd also put a new timing chain tensioner set in (the chain and sprockets should be fine with 50k on them). They are cheap.

 

Pete

[ww]

This engine is out of a 1981 280ZXT. Does that mean it's a 5 digit one then? So I can't be sure of the mileage?

 

In the states, the 1980+ ZX's all had 6 digit odometers. The 1979 is the only ZX with a 5 digit odometer.

[pjo046]

Ok, good. So then the 51 000 mileage is accurate. Guess I won't need to do anything with the engine then. Will of course run a compression test on it. Max boost I'll try to make will be 20psi. Is the stock headgasket and bolts good for that amount of boost? A complete chain-renewal set costs about 100$. Guess it's worth the money to change it all if I am changing the tensioner. Just so it's done.

 

As for the turbo specs Clifton, I'll go with a T3/T04B from James Thagard. He says this is the best bet for the money, and I won't need a spacer since it's not an E housing, thus I won't need to remove the studs from the exhaust manifold(which can be hard sometimes because they easily breake).

 

The turbo I get from him has the following specs:

A new Garret T3/T04B, Stage V turbine wheel/.63 a/r turbine housing

T04B hi-fi compressor wheel (55lbs/min), water-cooled & 360deg thrust bearing, Ceramic coated turbine housing, polished compressor housing, internal wastegate. I get this for 910$

 

Here's the reason James meant the B housing is better:

 

"The hi-fi wheel is designed for the B-housing and flows 55lbs/min whereas the largest wheel designed for the E is the 60-trim and it flows 52lbs/min. That is 30hp less worth of flow. The b housing will deliver more flow when comparing these 2 wheels. The upside to the B is that it does not require a

spacer. The spacer route requires that you remove the old studs

and replace them with longer ones. 50% of the time you are

guaranteed to break off a stud in the exhaust manifold. That

requires the manifold be removed from the engine. The downside to

the B is that it does not look as impressive as the E because it is

smaller in diameter. However, it is much thicker than the E.

Bottom line, this setup I have suggested will flow more than the

60-trim E setup"

 

"This turbo will outflow the T3/T04E 50-trim by ~80hp and will not adversely affect spoolup time. Basically, this turbo will use a larger(higher flowing)

compressor wheel shoved into a B housing instead of the E housing.

You must oversize the turbo on the L6 to reach your desired hp

goals. Again, this is because the L6 heads just don't flow very

well. A ported L6 head will flow 200cfm whereas a stock RB26 head

might flow 260cfm. Huge difference as you can see. The max hp

from this turbo is 550hp, but I would suspect you can reach

~425-450hp@wheels with this turbo and 25psi of boost. Trust

me when I say 450hp@wheels is pretty damn fast in a Z!"

 

Any comments on my choice of turbo is greatly appreciated!!!

 

And advice on what size -AN fittings an lines etc I'll need for the oil inlet/outlet and water inlet/outlet on this turbo.

[Clifton]

Good choice. You'll be happy you went with it, especially if you run 15 or more psi.

[HB280ZT]

pjo046,

 

I have a turbo setup from James and it works great. I also got the T3/T04B setup and I like it alot. It was easy to install, only had to change one part on the intake side and trim the original output pipe in two places to make it fit correctly. I would recommend that you use a 3AN line to supply oil to your turbo. Here is where to get the fittings that you will need to make this work: http://www.batinc.net/files/metric.pdf

 

I had to get a 3AN x M10 X 1.0 Convex union to adapt to the output oil block on the motor and I am waiting for the 3AN X 1/4 NPT fitting for the turbo input. You have to be very careful on the input because you do not have a lot of room to work. If you want more info drop me a line because I just put my turbo on and got it running over the holiday.

 

What are you plans for the starting point of this install? Will you be running an intercooler and some type of upgraded FMU? If not ask james to get you the lower pressure wastegate actuator to start with because mine came with a 15 psi actuator and I am not ready to put on the rest of the parts needed to use that much boost.

 

Enough for now but drop me a line if you have anymore questions.

 

HB280ZT

[TimZ]

Ditto on the -3 line for the oil supply. Use the teflon-lined hose only, preferably with a firesleeve.

 

For the water I use -10AN, although many use smaller. I would not go smaller than -8. Depending on where you tap into the water system, you might not have a very big pressure difference, so the larger lines will help. Also, try to route the water lines so that air can easily find its way out of them on its own - i.e., no upside-down "U" shapes in the hose routing.

 

On the head gasket and bolts, if you decide to stay with what is currently in there, you should still retorque the head bolts to the factory spec, and do it often (every few thousand miles). My guess is that 90% of headgasket failures are due to improper head torque.

 

Also, if you replace the head gasket, make sure to retorque it after the first heat cycle or two, and retorque it a couple more times after that, with a few heat cycles in between. New gaskets tend to squish down a bit after the first few heat cycles, which lessens the head torque.

[Cody 82 ZXT]

My guess is that 90% of headgasket failures are due to improper head torque.

 

 

You think that is even the case when someone uses studs aswell?

[TimZ]

You think that is even the case when someone uses studs aswell?

 

Without a doubt.

[pjo046]

Will run the Electromotive TEC3 engine management system. And run a 3-core spearco intercooler. So I guess the 15 psi wastegate actuator will be good!

[Cody 82 ZXT]

Without a doubt.

 

 

Not trying to steal the thread but, do you think I should retorque mine I've done so twice but, it was not long after the install two years ago.

[Cody 82 ZXT]

Will run the Electromotive TEC3 engine management system. And run a 3-core spearco intercooler. So I guess the 15 psi wastegate actuator will be good!

 

 

Should make for a nice combination. I don't know what your experience level is but, you might think about the lower psi actuator until you get the bugs worked out.

[pjo046]

As for experience with standalone engine management, none. As for experience with Z-cars in general though, I have some experience. Take a look at my personal link, and from there go to my homepage.

[Cody 82 ZXT]

Well it certainly looks like you've got some Z car experience. But, maybe someone with more standalone experience can jump in here but, if it were me I would start out at a lower psi. Maybe I'm to chicken to jump in like that but, it seems like that's a steep learning curve.

 

Like I said I'm not trying to say it can't be done but, I think some caution might be in order here.

[TimZ]

Not trying to steal the thread but, do you think I should retorque mine I've done so twice but, it was not long after the install two years ago.

If you aren't having problems currently, it's probably not an emergency, but IIRC the factory recommended retorquing every 15k miles. You should do it at least that often. If you are upping the boost, I would do it much more often. Mine gets retorqued about every 500 miles, but that's mostly because I'm anal, and I have it apart tinkering with it pretty often. Just follow the factory tightening sequence, and be sure to let the engine sit overnight (i.e., stone cold) before re-torquing. It only takes about 15 minutes to do.

 

Like I said I'm not trying to say it can't be done but, I think some caution might be in order here.

Agreed. Especially if it's your first time, start off with as low a bosst setting as possible, and get it running well at low boost first. Once you are satisfied with that, you can start upping the boost in small increments, dialing in the fuel curve as you go. You should get an exhaust gas pyrometer, in addition to datalogging whenever you are tuning.