what are the advantages to a ffim

[sethron71]

Chris,
There are about 10 different posts about FFIM. Is there a direct advantage:
Yes about half the IC piping plus less heat soak. The manifolds may not flow better at the low numbers they are flowed at yet under boost(huge pressure) the designs would. Check out these pictures and links to see some good information plus check Ron R's sticky.

Your idea of stock manifold with end plate added see below(made 440rwhp with one identical to this):

http://www.supramania.com/forums/showthread.php?t=4780
http://www.supramania.com/forums/showthread.php?t=5401

HTH,
Seth

 

[tig321]

actually IJ; I saw flow numbers which led me to purchase a modified stock GTE manifold to FFIM. It flowed approx. 7 % better than stock and more evenly across all cylinders.

Disced
do you have any pics of your manifold? Is it modified in the same/similar fashion as Sethron's

 

[whenmunkysfly]

Chris,
There are about 10 different posts about FFIM. Is there a direct advantage:
Yes about half the IC piping plus less heat soak. The manifolds may not flow better at the low numbers they are flowed at yet under boost(huge pressure) the designs would. Check out these pictures and links to see some good information plus check Ron R's sticky.

HTH,
Seth

kool thanks seth i saw one of you links says your making the ffim how much for the whole nine yards everything i need to make it work the bewst and look prity too lol

 

[supralee]

sethron71 - Can you post up more pictures of the stock modified FFIM?

 

[sethron71]

Those pictures were from 6 years ago, I would have to do some serious digging to find them. It was a cool mod of me when I first started making manifolds but we are miles past that these days with all my CNC stuff. I will see what I can find but no promises.

Thanks,
Seth

 

[Dan_Gyoba]

I can't see the reduction of intake pipe length having anything noticeable to do with lag.

Each linear foot of intake piping at 2.5" ID (Larger than what I'm using, since I'm using 2.5" OD tube.) is about 0.034 cubic feet. At moderate RPM, say 2000 or so, is about 100 CFM, so this introduces an additional 2ms between the air exiting the turbo and hitting the throttle plate, and this is assuming non boost conditions. At 4000 RPM the lag is reduced to under 1ms. Pretty simple math, that this isn't a big deal.

Heat soak... Well, I suppose that it must happen, but I don't know how much heat the intake air charge can pick up from the relatively small surface area over the manifold when you consider the turbulent airflow under the hood already.

This leads me to think that the primary advantage to a FFIM for a 7M is... Appearance. It certainly looks sexier.

Any other advantages that it may have I would argue are less important than many other easier, less expensive modifications that one might do first. If it is flow capability that one is interested in, then it would probably have an advantage in the ability to house a larger throttle body.

 

[Halsupramk3]

dan as always has good info. many other mods come first. the lag for a 2.5 inch ic pipe may not be much. i would guess that all the twist may add some time to lag but not much. i have modded all other engine parts first. i just am getting my FFIM installed with a 3 inch pipe and a 4inch deep IC. I think its 24" wide between the frames. people are making 600 hp on the stock manifold. the oem IC is worth replacing before the intake manifold.

has anywone flowed the stock manifold to see how consistent the runners are?

The FFIM is a much cleaner install. but since the oem manifold can do high hp i only got a ffim as the last major engine mod along with side to side IC.

putting on a much bigger turbo, FFIM, 3 inch ic pipe and large ic, 90 MM tb all at same time. we will see how this all works together soon.

 

[IJ.]

I changed to 3" pipes expecting some lag and on a 3540r actually saw a reduction.

 

[sethron71]

Dan I think your calculations are far to simple, I am on my phone so I will write more later but you are not factoring in things such coefficient of drag between the two different size pipes in relation to air velocity in use center of the tube. As well the number of bends, and the pressure drop over the distances per size. But I will write more when I get on a computer.

Seth

 

[Dan_Gyoba]

Yes, the calculations are simple, but the CFM rating is what must happen regardless. It's not the whole story, of course. IJ's experience of larger IC piping resulting in less lag, for example.

The corners are probably more important than the length, and drag more important yet.

I will still maintain that a FFIM and a change in IC pipe routing will not by itself produce significant gains. I think that other mods that people do at the same time (Larger TB, better intercooler, turbo, fuel etc) account for the majority of non-cosmetic gains that are experienced.

 

[Poodles]

I can't see the reduction of intake pipe length having anything noticeable to do with lag.

Each linear foot of intake piping at 2.5" ID (Larger than what I'm using, since I'm using 2.5" OD tube.) is about 0.034 cubic feet. At moderate RPM, say 2000 or so, is about 100 CFM, so this introduces an additional 2ms between the air exiting the turbo and hitting the throttle plate, and this is assuming non boost conditions. At 4000 RPM the lag is reduced to under 1ms. Pretty simple math, that this isn't a big deal.

Heat soak... Well, I suppose that it must happen, but I don't know how much heat the intake air charge can pick up from the relatively small surface area over the manifold when you consider the turbulent airflow under the hood already.

This leads me to think that the primary advantage to a FFIM for a 7M is... Appearance. It certainly looks sexier.

Any other advantages that it may have I would argue are less important than many other easier, less expensive modifications that one might do first. If it is flow capability that one is interested in, then it would probably have an advantage in the ability to house a larger throttle body.

Going by memory, but when Duane first switched to a RonR FFIM, he made I think about 45hp more.