Another Tmic vs Fmic thread...

Before the fire engines get started for all the flaming and heat I'll likely get-

 

YES I'VE USED THE SEARCH FEATURE! On here and google alike!!!

 

Most threads, on here and Nasioc, are the same ol "you don't need a fmic" "overkill" "turbo lag" "you're an idiot" "fmic is for 1320 racers only!" Etc etc...

 

I've read more then a book about all the current options for our cars. I'm stuck feeling that Perrin is the best bang for the buck afa tmic goes; however the GS unit takes the cake- and the wallet. Process west being somewhere near, but harder to find and issues with fitment seem to be inevitable.

 

I prefer to be a buy right buy once type.. which would point to Grimm speed. BUT, I'm having a hard time justifying dropping 1K on a top mount! While it will retain its resale value, I just don't see myself being content with the vf52 in the long run- nor a top mount.

 

So, that brings us to the oh so scary front mount. Being smack dab in front of the car it's heat dispersion/ resistance to heat soak- is frankly undeniably better then the stock located tmic. A lot of the hate for them is from claims of turbo lag, which with more piping (the curves in particular) seems reasonable, and the appearance of the big inter cooler up front.

 

I've also read a good tuner can combat that turbo lag to nearly be rid of it. In theory, once it's seen any boost and is pressurized once, won't it be sufficiently filled to deliver boost when applied? I'm far from a physicist, nor am a Subaru genius.. I have a few years flat rate Tech experience on Diesel trucks- all of which ran front mount intercoolers. As does the 10psi Honda next door! Lmmfao

As for looks...

Not only do I not mind the tank out in the open, in fact, I LIKE the look of a front mount... and while I don't like ricey, big spoilers, negative camber LMAO!!, and chose the LGT because I'm a 31 year old with three kids and not in high school... I'm also a proud Subaru owner. Now I know we all are here and we all have our affliction to our Legacys for our own reasons. However, unlike some of my fellow Leggo owners, I'm not going for the "stealth" "sleeper" "stock" look. Class AND grit I suppose... maybe when I make a build thread I'll dub it "NesSsDanK Mullet"! I prefer the lgt over the wrx, but not so much to hide that it's a bad ass Subaru!! I prefer not to be mistaken as a Nissan or a Fusion, so a front mount screaming turbo Scooby, is fine by me, and actually my preference.

 

So, after the long winded rant- I'm actively seeking hard data confirming I'd be leaving more then a negligible amount on the table going RacerX fmic over the Perrin tmic. I know it is an unfair battle of fmic vs tmic, as Grimmspeed is the king of top mount... but like I said, Im not gonna shell out a grand on a tmic. So price vs price that is the best comparison IMHO.

 

 

Love to see any links supporting factual data of controlled tests with identical variables on the RacerX fmic (uses smaller cores and piping from other setups so as to quicken the pressurizing) vs the Perrin Tmic. Any and all proof of the dreaded turbo lag, pressure drop, and lower boost levels is what I would've to see.

 

 

 

But dynos aside, please guide me to the light- and back it up with real life facts. Seems most the nay sayers are nearly 100% hear say, and no one has taken the time to actually do the math?

 

Correct me if I'm wrong... just looking for the down low

 

 

Cheers!

I'm certainly no expert but from all my research, the lag associated with front mounts is negligible and not noticeable in real world driving. Temps from fmic are considerably lower and I agree they look damn good peeking out under the bumper cover.

 

Racer-x is best bang for you buck and perfect size and fitment for our LGTs, and minimal modification required.

My sentiments EXACTLY!!!

 

Not to mention, I'd much rather spend my hard earned money towards a smaller up and coming businessman whose sole purpose of this kit was designed for and by us. Yes GS is on the boards and an absolute pleasure to do business with... just can't afford their most beautiful product. So that comment is more directed at the Cobbs and Perrins- which, I don't know first hand, may very well be an enthusiast turned fabrication supplier as well. But they definitely are house hold names in the suby world, and I know RacerX has made a name form themselves with the most upstanding customer service there is. Not a knock on the bigger companies, just another tip of the cup in favor of the fmic, and sending my business that way

https://forums.nasioc.com/forums/showthread.php?t=1815127&page=2

 

If you weed through some of the riff raft youll not only find supporting posts for real world FMIC users, but even a guy who had in shop talks with a Mr. Jeff Perrin... and after said talk went with a "stealth front mount"!

 

 

I also failed to mention that I live in the dry, dumb

-hot, New Mexico desert... our winters are short lived and laughable, plus the heat waves in the summer seem never ending.

 

 

With that said, I think I answered my own question... unless some actual tangible data exists out there that Google can't see to find

Front mount all the way. Have logged back to back street run tests on mine against the OEM top mount with the only differences being the intercoolers and BPV's. Negligeable difference if at all in most runs.

The only time I'd say the top mount has an advantage is in fuelling corrections at super low load, mine float back and forth as the time frame between the air hitting the MAF and then the O2 sensor is considerably longer than with a top mount. No noticeable difference when driving, just that the fuel trims never stay quite the same when logged

People do tmic when they don't want to deal with the piping. And it is dealing.

I've had a perrin tmic and now a GS tmic and I feel the GS is worth the extra cost in terms of fitment and turbo compatibility.

 

One thing to remember is that fmic's aren't laggy. It's a difference in transient boost response. A turbo will spool the same in either case, but between shifts (or off/on throttle) it can take slightly longer to fill all the piping. I'm with you on the look thing. I do prefer the intercooler peeking out from behind the bumper.

 

Now I have seen that someone is running in the 9's with a GS tmic... given that fact, I know that my intercooler isn't holding me back in terms of performance.

What about the front mount and reversed STi intake mani? Is that still a thing?

If you decide to go FMIC I highly advise the use of Murray Constant-Tension clamps. They do not leak if tq'd properly.

 

That said, I find a reason to MF my FMIC (RacerX) a few times a year. I still would not go back to TMIC.

It's honestly not a "real" debate. Go with whichever one you prefer. The advantages and disadvantages of FMICs and TMICs are well documented. There are slight trade-offs but either choice isn't going to kill your car.

If you decide to go FMIC I highly advise the use of Murray Constant-Tension clamps. They do not leak if tq'd properly.

 

That said, I find a reason to MF my FMIC (RacerX) a few times a year. I still would not go back to TMIC.

This. The racecar has them aftef Sgt.Gator had problems with leaking pipes at the track. He's now a vendor for them.

I've had a perrin tmic and now a GS tmic and I feel the GS is worth the extra cost in terms of fitment and turbo compatibility.

 

One thing to remember is that fmic's aren't laggy. It's a difference in transient boost response. A turbo will spool the same in either case, but between shifts (or off/on throttle) it can take slightly longer to fill all the piping. I'm with you on the look thing. I do prefer the intercooler peeking out from behind the bumper.

 

Now I have seen that someone is running in the 9's with a GS tmic... given that fact, I know that my intercooler isn't holding me back in terms of performance.

 

 

And 7s with a fmic... but seriously? Love to see that link. Fastest stock engine doesn't even pull 9s... isn't the record 10.02?

It's honestly not a "real" debate. Go with whichever one you prefer. The advantages and disadvantages of FMICs and TMICs are well documented. There are slight trade-offs but either choice isn't going to kill your car.

 

Only they arent so well documented, and just taken for gospel without any evidence... and then passed off on boards by word of mouth and snow balling into make believe facts... love to see some of those documents!

There's some of my 2nd gear comparisons. First 3 are with the FMIC and the rest are with the stock TMIC

 

http://i1149.photobucket.com/albums/o594/andy_mac1/4-2-16_zpspv0cixdp.png

So small and blurry man.. can you give a better analysis of what I'm looking at?

It's a "dyno" plot of his car with a TMIC and a FMIC. If the FMIC was causing later spool we would see the red, blue, dark green line, and orange shifted to the right.

 

From looking at the graph that's not the case. The FMIC v OEM TMIC didn't seem to have an impact on boost threshold (expected)

 

Where the FMIC might have caused a difference is response. But, my understanding is if you tune the BPV correctly, you should not have any negative impact on response. M Sprank wrote up a good piece on it and shared information from a vendor. Looking for the link.

 

A lot of information, but a lot of good information.

http://legacygt.com/forums/showthread.php/technical-info-bov-bpv-set-up-and-operation-150687.html

Thanks boss... I'm becoming more familiar with the dyno (jet?) program, just can't read much of it on my phone.

 

So this chart is verifying the turbo lag and less psi to be a myth correct?

Better volumetric efficiency with FMIC, happier motor. More power, cooler charge. Looks the biz. TMIC is easier, better packaging, no cutting, no fuss. No safety compromises. Better reliability, but harder to work around (need to take off TMIC to do just about anything). Sacrifices a little flow and more susceptible to heat soak, but better response and spool.

What Rhitter said really, its verifying that there was next to no difference in spool-up time and low end power/torque haven't taken a hit either.

 

And that program is just virtualdyno, used to display 'dyno' plots based on the logs taken in romraider.

The program he used is called virtual dyno. You take an open stretch of road (level) do so data logging and plug the data into that.

 

The chart shows that on his set-up adding a FMIC did not cause a delay in boost on-set.

I am not sure what you mean by less PSI though. Typically you can run more with a FMIC set-up.

 

Better volumetric efficiency with FMIC, happier motor. More power, cooler charge. Looks the biz. TMIC is easier, better packaging, no cutting, no fuss. No safety compromises. Better reliability, but harder to work around (need to take off TMIC to do just about anything). Sacrifices a little flow and more susceptible to heat soak, but better response and spool.

 

I think the better "spool" is what's at debate here. Andy_Mac is showing no impact to spool OEM TMIC to FMIC. Other than that great list of pro's cons. With the Racer-X FMIC there are no safety compromises, you are able to retain the stock bumper beam. I am also curious how strong that mean is. Is something like an ETS intercooler just as strong?

 

Sure if you through on the largest FMIC you can find, probably will take a hit. But if you keep the piping reasonable, once the system is pressurized wouldn't it be the same?

I am not sure what you mean by less PSI though. Typically you can run more with a FMIC set-up.

 

Can run more but don't need to. More power at lower boost due to increase in VE.

No one in this thread mentioned it... but a con I read was that a fmic will result in less psi due to the larger area the air has to travel and fill... I found that to be puzzling though. Once the system is pressurized that pressure will be what is. The initial filling might take half a breath longer but I didn't believe a turbo making 20psi on a stock tmic would magically drop to 18 due to the fmic.

 

But ya know... interweb geniuses and all

Yes and no. With my current, more aggressive tune when putting the top mount back on it actually requires 1-2psi more to get the same power levels.

Hot air is less dense so for the same g/s seen at the MAF a good FMIC, or good intercooler in general, will show less pressure for the same power.

So.... where's the thread about allocating funds for modz disease without the wife cutting off your nut sack?

 

To complete stage three, nor even mentioning what I have already (vf52, Id1000s, ebcs, etc) I'm looking at $1,375.. which is actually very good. May need to add more to the top feed conversion kit like lines.. I already put down 80$ for an STi fpr but need to research that more.

 

I can only use the "better mpg" "fixing the leak might as well upgrade the weak point while I'm in there" lines so much! LMAO.. I'm probably doing this backwards, as the remaining parts need at $1375 would pretty much get me Brembos.. all the extra powa is gonna have to be able to come to stop reliably!

 

I came from Jeeping, v8 grand Cherokee 35" tires long arms lockers beefy...

Just Empty Every Pocket.

 

Little did I know LGT has some kind of go broke quick acronym hidden in it too!