Changing Exhaust Manifolds

[Vicky B]

I have a couple of questions pertaining to my '93 Infiniti J30's right and left manifolds.

In order to change out the manifolds, do I actually have to pull the motor? And if the motor needs to be pulled, where can I find a set of engine slingers?

Anyone who could help me in this would be greatly appreciated. Thank you.

Vicky

[driverdriver]

Why do you need to replace the manifolds?

You realize that this is a very labour intensive job, where you need to pull out the engine (I would get an engine hoist).

You will need the FSM:

http://www.nicoclub.com/FSM/J30/

[swimshark]

I did mine with motor in car in about 2 hours. Yes I know I have a little more mechanical knowledge than others but it is doable with motor in car.


also i noticed i had an exhaust leak but couldnt exactly pinpoint it at first until i took it apart and noticed my manifold had cracked. this lead to me finding out there are 2 different styles of J30 exhaust. the 93-94 have welded exhaust with longer runners and the 95-97 (not 97.5) have cast manifolds that are log style. i ended up swapping both sides. this included replacing both exhaust gaskets after cleaning the heads up with wire wheel on my air tool and painting cast manifolds.

left side 95 - right side 93


there was my exhaust leak










a lot more room on each side of the motor now. you can see my oil filter relocation and engine mounts.



yes as you may be wondering, it was somewhat a pain to take these on and off with motor in car. i myself dont have he smallest arms (one of my nick names is popeye) so it was fun trying to contort my hands to get the nuts off the manifolds. being performance crazy, i am going to get it dynoed and see what power it makes. with the log style manifolds i will lose some power, but torque will increase.

[swimshark]

you do have to undo the ac low pressure line on the drivers side and then recharge the system. if you wanna do an oil change as well id do it before taking it off and leave the filter off as well to make it easier to work with it on passenger side.

[Vicky B]

Why do you need to replace the manifolds?

You realize that this is a very labour intensive job, where you need to pull out the engine (I would get an engine hoist).

You will need the FSM:

http://www.nicoclub.com/FSM/J30/

driverdrive, what exactly is an FSM? The link you provide above done not point me anywhere. In fact, it won't even open.

Curious though.
Vicky

[swimshark]

http://www.nicoclub.com/FSM/J30/1994_J30/em.pdf

has some info but mainly only for torque specs. fsm is the factory service manual. has all the information you will need to diagnose issues with your car.

http://www.nicoclub.com/FSM/J30/

make sure you have a pdf reader installed.

[Vicky B]

http://www.nicoclub.com/FSM/J30/1994_J30/em.pdf

has some info but mainly only for torque specs. fsm is the factory service manual. has all the information you will need to diagnose issues with your car.

http://www.nicoclub.com/FSM/J30/

make sure you have a pdf reader installed.

Swimshark, we just picked up a '93 service manual at Ebay for $30 used. I suppose this is one of the same type as you guys are referencing? The only problem with mine is that it does not give you any instructions to removing and/or installing exhaust manifolds. So, naturally, we are at a loss on this.

Also, both manifolds of mine are leaking and making loud noises. There is also no power going up inclines. I found a place who has a right and left manifold at a discount parts store, but I am uncertain if they are originals from an actual '93, or are they newer. I will still need to find out. He wants $60 a piece for them.

By the way, I called Nissan and found out that they will charge me $750 for each manifold, and each one would require some sort of adapter.

Does $750 each sound about right? To me, it sounds outrageous.

Thanks so much for your input on all of this. Sure appreciate it more than words could say.

Vicky

[swimshark]

i picked my manifolds up for the 95+ J30 and both were $50 total. 2 new gaskets was about $50 from nissan dealership. i could see if there are some still at local junkyards if you are interested. only thing i had to do on drivers side was rotate studs on the center cylinder to the head. on the 93-94 drivers side the studs are all the same pattern on all 3 cylinders. i can make a quick drawing to explain if unclear.

[swimshark]

its actually cheaper to buy them from Z1 but just call nearest nissan dealership and see what their pricing is and see if its worth to buy them and do the shipping. http://www.z1motorsports.com/product_in ... cts_id=572

here is about the stud configuration difference and how to remove the studs.

[swimshark]

shoot me an e-mail: swimshark1988@comcast.net and i can talk over with you to work on getting some manifolds out to you. the 95+ manifolds look different, but they bolt right up to the 93-94 exhaust.

[Vicky B]

Swimshark, I just sent you an email.

Vicky

[J30tChumpCar]

As a tech I say $750 is way out of line,for even both! Adapters? The only difference is switching 2 studs and there are a extra set of washers used on the early design that can be omitted if using cast units. The manifolds are something anyone with the ambition can do in a day or weekend depending on skill level, the a/c possibly in the way on the driver side is the biggest deal. Find a local shop, skip the dealer.

Swim, I would really like to see the dyno numbers on your cast iron logs,for those not familiar the earlier style are more a factory header, there is a reduction in the outlet diameter on the later cast units,a non issue if top end horsepower is not a goal.
Note:outlet flange fits either, manifolds are interchangeable, its just camera angle.

[swimshark]

i was pretty optimistic but the manifold didnt seem to make much of a difference in the torque. I made pretty much the same as before. First graph shows difference between automatic and manual transmission, second graph show with the dual maf intake swap and 3rd graph is highest numbers it has put down.







Only thing I hate now with the manual is the torque curve. Its high up and then drops off and lags until 4500rpm then picks up again. Im working with a few shops to see about acquiring a Nistune ECU setup and then have the car tuned. They are also possibly going to let me test their adjustable exhaust cam gear and intake gears. They said with tune and the gears, I could see another 20-30whp. I just dont have the money now to jump right in to it and do the research so trying to see if they can work something out. Basically make my car a shop car if I can or find some sponsors and Ill put their stickers on my car or something.

[yodawill2000]

Nice gain on the Dual Intake !!

[swimshark]

yah cool thing with the adjustable cam gears is that in a sense you can adjust where the powerband comes on by alternating either by retarding or advancing the cams. basically last 2 things i will do with the NA setup is the cams and tune. i dont want to get a bunch of NA stuff before I go TT. pretty much all the parts i have now can be swapped over later to the TT setup. friend has a 270whp NA 300zx but it has full motor work and a ton more to get it to that. it just gets pricey to make power NA but it is a blast to drive cause the power is instant and predictable.