difference in manifolds?

[Guest Unick Z]

i just realized that my 80' zx and my 75' z have 2 different intake manifolds.

i always knew that the 80' was non-egr, but today i realized that the 75' was noticably larger in the log area.. then saw they have different model numbers..

p82 i belive on the non-egr, and n42 of course on the 75'

i feel stupid for not realizing this earlier..

 

anyways....

yes i did search for the answer on here for about an hour with no luck..

can somebody shed some light on this for me?

any real differences?

[JSM]

I have an N42 and P82 also. Just different years. I think the log on the P82 is a little narrower at the end and has the runners with webbing. Other than that, very little difference from what I've seen.

 

TonyD would probably have some good insight or maybe BRAAP as far as real differences in flow.

[JSM]

Some good reading:

 

http://forums.hybridz.org/showthread.php?t=90619&highlight=p82+n42

http://forums.hybridz.org/showthread.php?t=120872&highlight=p82+n42

[Guest Unick Z]

Some good reading:

 

http://forums.hybridz.org/showthread.php?t=90619&highlight=p82+n42

http://forums.hybridz.org/showthread.php?t=120872&highlight=p82+n42

 

 

some good info there.. i was hoping to find some difference in flow or capacity...

any bench testes, or dyno charts from one to another?

[Guest Unick Z]

nobody has done any comparison?

[z-ya]

I use the P82 manifold on my race car. It has a 10:1 N42/N47 engine. The manifold was port matched to the head, and it has a 600mm TB on it (also port matched). I make 180WHP. I have not done any comparisons, but it performs well for me.

[JSM]

I use the P82 manifold on my race car. It has a 10:1 N42/N47 engine. The manifold was port matched to the head, and it has a 600mm TB on it (also port matched). I make 180WHP. I have not done any comparisons, but it performs well for me.

 

 

Man how do you fit the 600mm TB to the intake. That must be 1 heck of a port job!

[z-ya]

So I was off a little....

[Challenger]

I have I believe an 82 turbo intake maybe a 81, but it has the webbing, egr and the larger plenum. When I cut it open to do porting I found it to be quite smooth and looked like it would perform well.

 

http://forums.hybridz.org/showthread.php?t=134422

[Guest Unick Z]

...... so nobody has done a swap out?

[woldson]

I'am going to hazard a guess.

Nissian did not "neck" down the turbo manifold, so forced induction you problaly want to trust there engineering and not use the necked down one.

[BRAAP]

OE EFI intakes are very similar from a “power producing/air flow” stand point, (we are not discussing the visual aesthetics here).

There are two style of plenums, full length open box style for the early N/A and Turbo intakes and the necked sown plenum for the later N/A plenums are necked down toward the rear of the plenum. Another difference is webbing between the runners. Early intake had no webs, later intake have the webs. The Jury is still out if the webbing acts as a heat soak affecting IAT or acts as a heat shield reducing IAT, to many variables between different L-6 installations, engine bay air flows, exhaust manifolds and heat shielding etc for there to be a definitive answer. Regardless of the webbing, due to the restrictive runners of the OE EFI intakes, the discussion of which OE EFI intake is most ideal for performance, in my not so humble opinion is inconsequential. I say either use the one you already have or find the one that you like to look at when the hood is open and will still pass Emissions, (if you need EGR or not), and use that one.

 

Seat of the pants you will NOT feel any difference switching between open plenum and necked down plenums with the N/A manifolds. The runners are so choked down that any difference the plenums could/would yield in how then engine produces power is negated, not being realized. On the dyno, the necked down plenum vs open plenum N/A manifolds will perform the same! With runners capable of allowing the engine to breathe, those plenum differences would be small, and the consensus seem to favor larger Plenums, though there is some argument for smaller plenums in some applications.

 

Now the Turbo intakes have just slightly larger ID runners, (see information below), and if you researched OE EFI intakes, then you are aware that the runner ID of the factory EFI intake manifolds is only 53% the cross sectional area of the intake valve itself, ie.. the RUNNER is the restriction and any other changes even larger than stock throttle bodies will not yield any gains, till the restriction is no longer a restriction, i.e. the runners of the manifold! The Turbo runners are only slightly larger than the N/A runnners and should yield approx 2-4% more power over the N/A, again, nothing you could feel seat of the pants, and there is FAR more power to be gained in dialing in the tune, i.e. AFR’s, ignition timing and getting the ignition system up to snuff, i.e. Quality wires, (Taylor plug wires are NOT what I'm referring to when I say quality wire. Jacobs, Nology, and Magnecor ARE!), NGK spark bolts with projected tip for N/A engines.

 

As of late, there has been a few members here making an effort to improve air flow with EFI manifolds, building their own manifolds and also carving up OE intake manifolds in an effort to open up the runners to allow the engine to breathe more freely. Those folks are on the right track.

 

 

Here is a cut and paste of a post I made just little over a year ago in another thread… These exact Turbo manifolds measured below are currently for sale, listed here…

 

http://forums.hybridz.org/showthread.php?t=132395

 

 

This thread fired me up to spend this afternoon measuring a few EFI intakes that we have laying around the shop and posting those results. Mind' date=' you I only measured 4 manifolds. 2 of them are Turbo intakes, the other two are N/A. One of the N/A is a non EGR [i']P-82 [/i]off a friends 280-ZX, the other is a NON EGR N-42 intake manifold. I have no idea what years the Turbo intakes are, sorry. I’m sure measuring all the EFI intakes that Nissan used would be more accurate, but I strongly feel the results I acquired and posted here are good enough for the intent of this thread, i.e. I don’t think measuring them ALL will reveal anything not found here.

Also, keep in mind, these are cast parts, and as such, there are some pretty drastic differences between manifolds, let alone within each runner due to the casting molds etc. I started out also measuring the runners horizontally as well as vertically, but the casting part line was skewing the measurements so much, and being as the runners are, for the most part round not oval, I just used my vertical measurements.

 

There have been strong claims made both ways as to whether the Turbo intake manifolds have larger diameter runners as compared to the N/A manifolds, (I have taken part in those discussions myself).

 

In summation, yes the Turbo manifold has ever so slightly larger runners, ….

 

 

Here are the details of this afternoons measuring session on these manifold runners.

 

I measured all 6 runners of all 4 manifolds and I measured each and every runner in 3 different locations along the length of the runner. I was using my machinist snap gauges and Mitutoyo 0-12” dial caliper. First measurement point “A”, is 4 ½” from the head flange. Point “B” is 2 ½” from the head flange. Point “C” is at the head flange, ¼” in from the flange surface.

 

 

Top pic shows the manifolds that were measured.

 

Second pic shows the locations at which the measurements were taken, “A” “B” and “C” respectively.

 

Third pic is each and every measurement taken at all three points in all runners of all 4 manifolds, to within .005”. Average runner diameters per location, avg per individual runner, and avg overall. At the bottom is the square area of the averages and the % of difference between the two N/A vs the Turbos, (I used 1.308” Sq/in for the Turbo Reference).

 

 

 

 

 

 

Hope that helps…

Paul

[Guest Unick Z]

thank you paul..

that was just the kind of answer i was looking for..

as a follow up question, how big can these factory manifolds be ported?

does it make a sizable difference in power?

[woldson]

Holy smokes!

Braap thankyou for such a great write up! Ummm.... can't think of any other way to say thankyou for such a lifetime of experience,,,,..... Oh well.

 

Unick, Braab has given you a ton of insight. Now don't forget one very valuable piece, (I was even suprised, because this has been asked elsewhere), the information you seeked was within the search function.

 

I know there is a ton on porting and matching in that search button.

Have fun!

[Challenger]

As of late, there has been a few members here making an effort to improve air flow with EFI manifolds, building their own manifolds and also carving up OE intake manifolds in an effort to open up the runners to allow the engine to breathe more freely. Those folks are on the right track.

 

After taking apart my turbo intake Im wondering if there are really any gains to be had. Im going to try and open the runners as much as possible, but from looking at the thickness of the metal I wont be able to do to much, hopefully it will be of some benefit.

[Tony D]

Information Disseminator!

 

Your sheep will be fruitful this season with you disseminating like that all over!

 

I had someone argue once about N42/P82 runner size. That Excel summed up my general comments to the guy. He was not convinced. He was also 1 second slower in the 1/4 mile and swore I had a cam in my rat-trap POS Fairlady.

 

Small details, stacked up, make for a fun car. Like BRAAP posted, there is more to it than just an intake manifold. Spark plug wires are one of my faves as well. People think they last forever. They don't.

 

I babble late on in the evening. Forvgive me.

[Guest Unick Z]

Information Disseminator!

 

I had someone argue once about N42/P82 runner size. That Excel summed up my general comments to the guy. He was not convinced. He was also 1 second slower in the 1/4 mile and swore I had a cam in my rat-trap POS Fairlady.

 

Small details, stacked up, make for a fun car. Like BRAAP posted, there is more to it than just an intake manifold. Spark plug wires are one of my faves as well. People think they last forever. They don't.

 

I babble late on in the evening. Forvgive me.

 

soo.... it is worth porting out is what your telling me?

[woldson]

Tell us what your goals are for you car.

You have been given an extream amount of insight, with out further knowlage your question becomes......... well lets just say "old".

(information is there in the search function)

[Guest Unick Z]

the search function has been utilized.. lot's of answers there, most of which are conflicting..

i've been moding and racing cars for a while, but up until now have left my Z mostly stock..

next step is thowing some boost through the old girl.. i rebuilt the engine about 10k ago. it's a dished piston 8.3 compression motor. i have a factory turbo kit, but i'm upgrading some things first..really the only factory thing i'm keeping is the exhaust manifold from that kit.. knowing that i'm gambling by at first running a stock n/a ecu i'm not going to run much more than moderate boost.

i was thinking 370cc inject.

i have a mkIII supra fmic.

aftermarket rising rate fpr

electronic boost controller and external wastegate

 

so the intake manifold is of large concern for me... money is always an issue, so if i can get away with spending less i will..

 

sorry to rant on... i know how annoying it is to read

[woldson]

So I will through this out there, mind you I'am still learning myself, consitrate on the exught side for getting the best bang for your buck.

 

From what I've learning is that any restirictiveness from the manifold to the turbo lowers avalible power, AND ANY restivitivness in the exught after the turbo back logs the whole system.

You can have a ausome intake and a 2in down pipe and 2in exught and the intake is worthless (knida).

You have a stock intake and 3in from the turbo all the way back will yeild far better power output.