This Is Why A JZ Manifold Cannot Be Used On A 7M

[Mr Bojangles]

I've seen this question asked so many times and answered incorrectly just as many times so I thought I would put this together so I can just post a link and save everyone the time of repeatedly answering it.

The JZ intake manifold will not and does not fit on the 7m, nor will the upper half of a JZ manifold bolt to the lower half of a 7M intake and here is why.

The JZ lower manifold (right) is completely different from the 7M (left) in the placement of fuel injector galleys, bolt pattern, and runner/port shape.

Another picture of the JZ (left) manifold and the different shape of the runners and bolt patterns from the 7M (right)

I hear a lot of talk about welding a JZ upper manifold to a 7M lower manifold, please look at this before considering doing it.

Here is a 2JZ (TOP) intake and a 7M (BOTTOM) intake. These are the top halves only.

They look fairly similar right? Now look at a 2JZ gasket laid over the 7M intake.

Not only are the runners in different positions, so are the mount points.

This is the same JZ gasket laid over the lower runners of the 7M intake. Here you can really see how different they are.

The last picture shows how far off they would be from lining up and that is more mismatch than any port job could fix. Not to mention that if you welded around the outside of the runners you would have no way to get in and weld the bridges between the runners. That would allow all kinds of F'ed up cross cylinder air flow and pressure gaps that would ruin the efficiency of the intake.

If you absolutely have to have a FFIM then buy a legitimate one or have one fabricated for you. Either way it's not going to be cheap but do you really want your car to be built as cheap as possible? If you can't afford it, please please stick with the stock intake.

 

[hvyman]

Props.

 

[oldsking]

Ive seen the welded flange ones.... Id hate to test how the velocity works on that lol

 

[Suprapowaz!(2)]

FFIM on a 7m is purely a bling factor anyway. There was a guy running mid 9's with a stock 7m upper and lower intake manifold. We all know who he is. You can make power, and go fast with the factory manifold.

 

[GrimJack]

Well put, OP.

 

[Supracentral]

Stickied.

 

[Dani87x]

Great input Mr. Bo. Thank you very much, very helpful info indeed.

 

[Turbo Habanero]

very good advice

 

[Nick M]

Seems like plenty of material for extrude hone...

 

[oldsking]

I agree, the FFIM is bling and easy on intercooler piping routing. If you look at the direction of air flow on the stock set up it is far more superior as it can evenly flow into the cylinder chambers from the top unlike the the FFIM where it goes in through the front and has to travel alll the way to rear.

 

[Mr Bojangles]

I've gotten so much from this place, it's nice to help out.

 

[Enraged]

I agree, the FFIM is bling and easy on intercooler piping routing. If you look at the direction of air flow on the stock set up it is far more superior as it can evenly flow into the cylinder chambers from the top unlike the the FFIM where it goes in through the front and has to travel alll the way to rear.

Keep heating your intake pipe with your turbo then :wavey:

I would imagine there is a reason that Toyota changed to the FFIM design on the motors after the 7M...

The old argument of "blank went blank.blank with a stock intake manifold proves its better" argument is stupid. Those guys would likely make more power, have lower intake temps, have better response, and run better times had they had a properly design FFIM. You are correct though, that if the design of the intake is poor, it could severely hurt the motor.

 

[Suprapowaz!(2)]

The old argument isn't stupid if it's being proven. How much cooler do you think a properly set up FFIM lowers your air charge? And think about this. The cylinder header runs at a certain temperature. Your intake manifold is bolted to that cylinder head. The cylinder head heats up the intake manifold the same no matter where the intake pipe is entering the manifold. Direct heat caused from manifold being bolted to the head is hotter than indirect heat from the pipe sitting over the head.

If you really want to reduce intake air temps then a water/methanol kit would be money better spent. Its benefits out weigh a properly set up FFIM, and cost much less. But it doesn't have that bling factor though.

 

[nofx230]

i know a lot of guys try wrapping the intake pipe in heat wrap or what not to help with a colder charge but if the motor sits at say a traffic light for 5 mins and gets heat soaked and then once you start moving again the pipe thats wrapped in tape or insulating wrap will hold all that heat in until it cools if ever so wouldn't it just be a good idea to not wrap the pipe in the first place???


don't get me wrong i love the way the ffim set ups look to but the amount of money spent to properly swap over to it doesn't seem worth it unless your building a show car or are ocd about the way things look under the hood
one question i did have bout options for a colder charge of air is what about a bigger intercooler that say the size of the HKS or the driftmotoin IC kits theres gotta be bigger IC options out there and how much bigger can you go before you just start wasting time?

 

[GrimJack]

I've done temp monitoring in traffic... temps spike when you're sitting at idle, stopped, but drop again in literally seconds as soon as you give the engine throttle.

 

[Suprapowaz!(2)]

Exactly. The velocity of the air coming from the intercooler to throttle body under WOT is probably way too fast for the pipe over the engine to heat it up enough to make that much of a difference.

Does a FFIM look better than the stock set up? Hell yeah. Do I personally care about the looks? No. I do remember years ago someone posting up performance gain, but that could also be attributed to the much larger Infiniti throttle body they used.

 

[Enraged]

a side benefit, but how long does it take to change your spark plugs? takes me about 2 minutes.

to each their own, and if you are happy with the stock intake, I won't be able to persuade you otherwise.

I think it's like the SP quickspool valve, in that your car will work fine without it, but it would be better with it.

 

[Suprapowaz!(2)]

a side benefit, but how long does it take to change your spark plugs? takes me about 2 minutes.

I think it's like the SP quickspool valve, in that your car will work fine without it, but it would be better with it.

Quicker spark plug change would be cool, but I'm not going to spend $1000 to do it.
Quickspool valve analogy is apples to oranges.
I like my ugly stock intake manifold thank you very much. :icon_razz

 

[Enraged]

who says you need to spend $1000? learn to fabricate

 

[Nick M]

Keep heating your intake pipe with your turbo then

Another that knows just enough to get himself into trouble. The air is moving not static, and the turbocharger has a heat shield.

Exactly. The velocity of the air coming from the intercooler to throttle body under WOT is probably way too fast for the pipe over the engine to heat it up enough to make that much of a difference.

Yep.

I would imagine there is a reason that Toyota changed to the FFIM design on the motors after the 7M...

And how much stuff did you take off the car that Toyota put there but didn't really need? And just to remind you, Toyota discontinued the JZ for a naturaly aspirated V6. Therefore, the V6 is better. Following your logic to its natural conclusion.

The old argument of "blank went blank.blank with a stock intake manifold proves its better" argument is stupid. Those guys would likely make more power, have lower intake temps, have better response, and run better times had they had a properly design FFIM. You are correct though, that if the design of the intake is poor, it could severely hurt the motor.

You would have a leg to stand on if you knew what you were talking about. There is one benifit, the shorter intercooler pipes. And that was done because the JZ is a gutless wonder down low. If the plenum is bigger and the runners bigger in diamter and shorter in length, then you would have a case. But that isn't the case. You are making the case for front facing, not an improved manifold. By the way, the fastest drag car in the US uses the stock manifold. Ported I would guess.

Hey I got an idea. Take the man hours you spent changing over, then see if my taking 30 minutes to change plugs every 2 years is the same.