Thoughts on FFIM's and throttle response

[turbotank88]

Hey guys, I honestly don't know about the air dynamics of manifolds, but I wanted to get some insight with those who have experiencing converting from the stock intake manifold to a FFIM.
I've been surfing around both here and supraforums on a topic related to the different designs of FFIM's (long, mid, short runner), the stock intake manifold, and intercooler piping vs. throttle response.
From my understanding, shorter intercooler pipe routing can increase throttle response, is this true? How about 2.5in vs. 3in piping?
I've also read that short runner intake manifolds produce high end horsepower, while long runners provide low end torque, thoughts?

 

[Nick M]

A front facing intake manifold gains you nothing. If anything, it limits airflow to the rear cylinders in a small way. Unlike EGR which is routed to the middle. I think many don't know that when they say (wrongly on multiple points) that EGR causes the headgasket problem because the rear gets too hot. And also want a FFIM because magically airflow then works different.

On the Supra 7MGTE with its longer routing and inline design going straight across the front, and not back around is better. That should be obvious. Routing of the charge air pipes back over the turbocharger is not optimal.

 

[Tnice17]

I believe that the gains of the shorter piping can be made up else were. ^^ interesting on the HG issue Nick M.

Personally have been on the fence about doing it for a while now. I always always always compare the gain/$. Sometimes even if the gains are small or next to nothing, i will do still do it just for the eye candy if i can do it for less than $300 and not alter other components to make it work.

If street is more than 50% off your driving, i would say dont do it. Trying my best to take my own advise with this one too!

As for the intake charge, if your intercooler is still with in efficiency, i wouldn't think twice about the routing over the engine/manifold. Proper turbo blanket and heat shield will do the job in my opinion.

 

[Nick M]

I don't know when the non-sense about EGR started. I read about it at Mark Tozer's forum back at the start of the new millennium. EGR causes detonation, EGR causes BHGs. I am not sure where they get that stuff from. Maybe it was the old SOGI mailing list. I just don't know. EGR flows to all the cylinders, and it causes the opposite of detonation by diluting the oxygen content. Yet the same clowns who said the HG at cylinder 6 was from EGR not flowing evenly then said in the same breath that a FFIM flows to all cylinders just fine.

But back to your subject. A bigger plenum with larger diameter runners and shorter length will increase top end.

 

[Emeraldage]

FFIM unless you're making massive power is really never worth the hassle for $ and work and power gains. More of an aesthetic thing for sure, I might do it some time as well to my 2jz swap just because it looks so friggin cool. I have no idea how it works either but the 7m long runner and butterfly system was made to help mroe low end torque I thought. May be slightly faster throttle but shouldn't make a difference. If you have a 3" tube filled of water and a 2' tube filled of water, when you put water in one sidethey both will push water out the otherside at the same rate! But obviously there's always very slight extra friction but I can't imagine it makes a real difference. I'm rambling too much.

 

[RacerXJ220]

Air gets turbulent towards the speed of sound and how restrictive the pipes are. The math is on other forums.

700rwhp is fine with 2.5 inch pipes.

Those shooting for more may want to go with a FFIM with a huge plenum/throttle body to accommodate larger piping for large/efficient turbos and lots of boost.

The rear cylinders seem to burn just fine on high HP setups. I really think the design has a lot to do with it.

I do know from experience, the stock 1JZ intake manifold is the worst of all. It just wasn't really made for high RPM power. Rather, the 1J manifold was made for low end response and torque.

I bet you will see a neat difference up top. This is what 2J motors with big turbos are known for. Those manifolds flow the best, IMO.

 

[turbotank88]

Great info guys, thanks for the input. So if my focus is looking toward increasing low end torque and response, it might be better to stay with the stock manifold? I'm guessing fuel mapping would probably be a better option of doing this?

 

[black89t]

when i was figuring out my na-t build my goal was a responsive setup that could do autox, drags, track days, or just hit the road. at first i wasn't going to go with a ffim but then when i tore down the motor for the tt hg/arp studs i was like im never putting that pos back together. i would dread changing plugs with the stock intake, ic piping is hell, hard to fit large turbo, and it looks like shit. plus the ffim would helped with my build goal.

the 7mgte isn't as bad as the 2jzge but still has similar benefits to going ffim. your understanding is true. i went with 2.5" ic piping, stock throttle body, and ffim with response in mind. the smaller shorter piping is less volume to fill. the stock throttle body is like a hose nozzle. going with a 3" ic piping, gigantic throttle body, ect like some people think will give them more hp is wrong! the only time those help is when you're pushing tons of air like over 700whp. under that all its going to give you is more lag.

i decided to make my own. after researching on a boosted car the long runner and short runner doesn't really matter as much compared to in an n/a motor since once its pressurized its a mute point. people were saying the rear cylinders with ffim by design will get more air and run leaner since the air shoots to the back passing the first ports. to combat that i set up my throttle body to open sideways compared to most on the market open flat. so on part throttle the plate directs air towards those front cylinders. after running the manifold for years now the plugs always look identical the rears never look leaner. my throttle body placement might have helped that but all other cars ive seen with ffim don't seem to have the problem so idk for sure.

really its up to you. you can have a responsive nice setup without one. will going to one make it more responsive yes but not necessary. turbo choice and exhaust housing size is what really is going to determine when you hit full boost and how it pulls to redline. heres a pic of mine

whats your hp goal?




and where did egr come into this lol

 

[Rollus]

I've read that stock manifold won't fill correctly #3 and #4.

I've seen flow simulation for FFIM that look like this: equal filling:

There is no EGR usually on FFIM, but can be provided as an option sometime.

On stock manifold, it feed the #6, maybe #5 also.

Until the hole is a gallery going to the throttle body (I don't know), it's no rocket sience to understand gaz entering here won't go to the firsts cylinders, because air mass and flow from TB to valves is stronger.

 

[quake]

i have tested many different setups over the years with dyno data to back up what i thought may or may not work. Their are gains to be had from a ffim over a stock plenum

 

[Emeraldage]

I've read that stock manifold won't fill correctly #3 and #4.

I've seen flow simulation for FFIM that look like this: equal filling:

There is no EGR usually on FFIM, but can be provided as an option sometime.

On stock manifold, it feed the #6, maybe #5 also.

Until the hole is a gallery going to the throttle body (I don't know), it's no rocket sience to understand gaz entering here won't go to the firsts cylinders, because air mass and flow from TB to valves is stronger.

Do you think this applies to the center cylinders always running hot and usually where the BHG originates?

 

[RacerXJ220]

Computer simulations may not exactly represent real situations.

That is why you make a huge plenum/manifold so that air will always be distributed equally at a specific resonating frequency tuned towards the RPM band target (ideally), and it does with race manifolds. The amount of air flow and the harmonic frequencies made inside the manifold, both play a role in how long the runners should be in relation to plenum size, in order to get the most power.

Not all intake manifolds are made equal. A+ to making your own, I wish I tried. Maybe next time

Dyno/track testing is where you prove it's efficiency/flow. I think SF had some dynos of different intake manifolds done a very long time ago, and I forget which one came out as the worst.

 

[Rollus]

@RacerXJ220

Yes, computer simulations may not exactly represent real situations. The one I posted is from Sethron's manifold, who made several simulations to optimise plenum volume/form factor.

I agree with your explanation about manifold tuning.
I'm interested in a link to these dynos..

Do you think this applies to the center cylinders always running hot and usually where the BHG originates?

Actually it seems to be a gallery so all cylinders may be feed:

BHG happens anywhere I think, but usually between two of the three last cylinders. I made a bhg between 3&4 with egr blocked, so I would assume it's not related

 

[turbotank88]

when i was figuring out my na-t build my goal was a responsive setup that could do autox, drags, track days, or just hit the road. at first i wasn't going to go with a ffim but then when i tore down the motor for the tt hg/arp studs i was like im never putting that pos back together. i would dread changing plugs with the stock intake, ic piping is hell, hard to fit large turbo, and it looks like shit. plus the ffim would helped with my build goal.

the 7mgte isn't as bad as the 2jzge but still has similar benefits to going ffim. your understanding is true. i went with 2.5" ic piping, stock throttle body, and ffim with response in mind. the smaller shorter piping is less volume to fill. the stock throttle body is like a hose nozzle. going with a 3" ic piping, gigantic throttle body, ect like some people think will give them more hp is wrong! the only time those help is when you're pushing tons of air like over 700whp. under that all its going to give you is more lag.

i decided to make my own. after researching on a boosted car the long runner and short runner doesn't really matter as much compared to in an n/a motor since once its pressurized its a mute point. people were saying the rear cylinders with ffim by design will get more air and run leaner since the air shoots to the back passing the first ports. to combat that i set up my throttle body to open sideways compared to most on the market open flat. so on part throttle the plate directs air towards those front cylinders. after running the manifold for years now the plugs always look identical the rears never look leaner. my throttle body placement might have helped that but all other cars ive seen with ffim don't seem to have the problem so idk for sure.

really its up to you. you can have a responsive nice setup without one. will going to one make it more responsive yes but not necessary. turbo choice and exhaust housing size is what really is going to determine when you hit full boost and how it pulls to redline. heres a pic of mine

whats your hp goal?




and where did egr come into this lol

Interesting. The hose nozzle likeness makes sense. I'm currently running 2.5 hardpipes myself albeit still on stock pipe routing. Really I'm not looking to push the boundaries that much, possibly high 300's-low 400's.This project is going to be mostly sliding sideways, so high horsepower isn't really necessary. With limited rpm's on the 7M I figured that torque and response would be more important by putting more emphasis of the powerband at lower revs. Unless I'm going about this the wrong way, please correct me

Interesting concept of setting your throttle body sideways like that. First I've see of that type of design from other 7M's I've seen, nice setup btw!

 

[RacerXJ220]

Right about RPMs. Keep the speed of the pistons lower, engine will live longer. The 7M has a beefy stroke as it is.

 

[Nick M]

On stock manifold, it feed the #6, maybe #5 also.

Until the hole is a gallery going to the throttle body (I don't know), it's no rocket sience to understand gaz entering here won't go to the firsts cylinders, because air mass and flow from TB to valves is stronger.

Maybe they get this phony EGR information from you. :biglaugh:

Take a look inside the plenum some time. If it only flowed into cylinder 6 and 5 then it would not do its job.

 

[Rollus]

You didn't read enough.
Because I hadn't the answer, I've looked for information you could have provide, instead of just bashing people and collective (mis)understanding/knowledge/memory.

Actually it seems to be a gallery so all cylinders may be feed:

BHG happens anywhere I think, but usually between two of the three last cylinders. I made a bhg between 3&4 with egr blocked, so I would assume it's not related

 

[Nick M]

I wasn't bashing you. But you did say this;

it's no rocket sience to understand gaz entering here won't go to the firsts cylinders, because air mass and flow from TB to valves is stronger.

My mistake if I misunderstood you were not saying what is demonstrably wrong and shown for more than a decade.

 

[Rollus]

Please... what I'm saying is demonstrably wrong if not quoted in full... because I did not say this, I've said that:

Until the hole is a gallery going to the throttle body (I don't know), it's no rocket sience to understand gaz entering here won't go to the firsts cylinders, because air mass and flow from TB to valves is stronger.

And then..

Actually it seems to be a gallery so all cylinders may be feed:

I needn't to argue. My first statement has a condition (the gallery), I've searched, and found this condition wasn't true. That's it, have a nice time, and please stop quote me wrong

 

[Nick M]

Computer simulations may not exactly represent real situations.

This doesn't apply to us, but GM used really good simulation software to design the LSX heads. They knew how good they were going to be. It was the improvement in the software and computing power. For the rest of us, that is why we have a flow bench.