[Arkin]

If I going to flush my f30 n55 with BM3, should I get the 5" or 7.5" intercooler? Some said if you dont need a bigger intercooler and you put one in, it will degrade your performance.

[n55david]

Originally Posted by Arkini

If I going to flush my f30 n55 with BM3, should I get the 5" or 7.5" intercooler? Some said if you dont need a bigger intercooler and you put one in, it will degrade your performance.

get the vrsf race. or the 6.5 comp.

it will never hurt you. never

[gameson]

https://f30.bimmerpost.com/forums/sh....php?t=1872731

Good read

[thejeremyman9]

Originally Posted by Arkini

Some said if you dont need a bigger intercooler and you put one in, it will degrade your performance.

False.

As someone who got a 5'', then later went to a race IC, just get the race IC to begin with...

[rjd_F30]

The only time an upgraded intercooler will "degrade" your performance, is if you get an absolutely gigantic one that will cause some pressure loss. None of the common N55 FMICs on the market do that in a significant way though, even the really big ones. Definitely upgrade the FMIC, it's a must when tuning this engine.

[SuperLomi]

I think the biggest considerations are any trimming you need to do to fit the I/C.

5" IC fit with no problems, and will be fine for DD/spirited driving - if not optimal.

The 6.5" VRSF also fit's with no trimming, and is generally considered the "best option" in this size range/style IC - but comes with some risk due to quality/CS issues people have had with VRSF (fwiw. I went this route recently, and had no issues getting the product, and initial inspections looks good. Have not installed it yet.)


The 7" Race I/C require some trimming to fit right, and so may not be for everyone if you don't want to cut things.

You could also consider non-stepped options, like ARM/ER - which have more frontal area than the VRSF, but less depth (frontal area is more important than depth)

[mike@x-ph.com]

Originally Posted by Arkini

If I going to flush my f30 n55 with BM3, should I get the 5" or 7.5" intercooler? Some said if you dont need a bigger intercooler and you put one in, it will degrade your performance.

Depends on your mods, if you are stock or stage 1, get the 5". It's a direct fit with no trimming and more than enough for a daily driver. Good options are Wagner EVO I, BMS, MAD (they're releasing a new high-density core).

If you are running stage 2 or more , get the 7.5" intercooler. Good options are Wagner EVO III, BMS Race, MAD Race

[thejeremyman9]

Originally Posted by SuperLomi

The 7" Race I/C require some trimming to fit right, and so may not be for everyone if you don't want to cut things.

You could also consider non-stepped options, like ARM/ER - which have more frontal area than the VRSF, but less depth (frontal area is more important than depth)

Race does not require trimming, i just installed a VRSF race recently with no trimming as have many other people. You only need to trim if you are too lazy to install it correctly and struggle through a challenging install.

We discussed the non stepped ICs to death in the other thread, i personally would not buy one now that i know they don't have fan tabs and they are spaced back from the fan, but OP can make his own decision there.

[mike@x-ph.com]

Originally Posted by thejeremyman9

Race does not require trimming, i just installed a VRSF race recently with no trimming as have many other people. You only need to trim if you are too lazy to install it correctly and struggle through a challenging install.

We discussed the non stepped ICs to death in the other thread, i personally would not buy one now that i know they don't have fan tabs and they are spaced back from the fan, but OP can make his own decision there.

Trimming is not mandatory on the bigger intercooler, but it makes the install lengthier and more challenging.

It takes less time to trim and install the intercooler easily than go through the hassle of getting it to fit without cutting, especially if this is your first large intercooler install.

[thejeremyman9]

Originally Posted by mike@x-ph.com

Trimming is not mandatory on the bigger intercooler, but it makes the install lengthier and more challenging.

It takes less time to trim and install the intercooler easily than go through the hassle of getting it to fit without cutting, especially if this is your first large intercooler install.

Well yeah, obviously its easier to trim, but there's no reason to do so and negatively affect the car in the process...

[johnung]

Originally Posted by Arkini

If I going to flush my f30 n55 with BM3, should I get the 5" or 7.5" intercooler? Some said if you dont need a bigger intercooler and you put one in, it will degrade your performance.

In perfect intercooler world, an FMIC would be installed that has exactly the capacity to cool the intake air demanded by the horsepower of the modded & tuned engine.

Turbo cars come from the factory with stock Intercoolers that have the size and cooling capacity to match the stock engine. Modding/Tuning stock engines for more power causes a higher flow of hot air into the stock intercooler. This can over run its capacity to cool the air fast enough. This causes the engine to start making adjustments to protect itself which can lead to additional timing adjustments, cutting throttle and going into limp mode. The term Heat Soak is when the driver feels the engine losing power due to these adjustments because of the Intake Air Temperature (IAT) being too high entering the engine.

Heat Soak was primarily an issue at the race track where modded high performance engines needed a lot more cooling. They had to race at high revs which generated a lot of heat that made IATs go up. Big intercoolers were needed to prevent Heat Soak on the track. Turbo Lag wasn't much of an issue because race tracks don't have standing starts and low rev driving like daily drivers on the street.

What you may have read is that installing an intercooler with much more capacity than is really needed, can potentially cause delay or turbo lag. That's basically the amount of time that it takes from when you put your foot down on the accelerator until the engine can build up enough boost pressure for the driver to feel the power come on.

This delay would be most noticeable when accelerating from a standing start like from a stop sign or when waiting at a traffic light and it turns green. Other situations might be suddenly trying to pass another car or when trying to accelerate to merge onto a freeway.

The air intake system path on these turbo cars consists of three pieces:

1) the Turbo To Intercooler (or TIC) Pipe that delivers the hot air to the Intercooler,

2) the Intercooler itself that cools the hot air,

3) and the Charge Pipe (CP) that delivers the cooled air to the engine.

The TIC and CP pipes are pretty much the same size whether stock or aftermarket. It's the Intercooler that has various aftermarket options for both volume and cooling core specifications.

A car manufacturer like BMW has engineers to design and test to determine the perfect stock intercooler. In the aftermarket the most common tool is the same as been used by trackers for decades, the Intake Air Temperature. It's pretty easy to take engine logs from Wide Open Throttle (WOT) runs in 1st to 4th gear. The values of the IAT and the Ambient temperatures make it easy to judge how well the Intercooler is cooling the hot air being thrown at it by the modded engine.

So at some point the correct size & design of an aftermarket Intercooler will adequately cool the maximum that the modded engine can throw at it. A potential turbo lag issue may be created if a much larger intercooler is used than is needed to keep IATs down to a working modded engine level.

One analogy might be a balloon representing the Intercooler and two straws at either end representing the two pipes. Well if the balloon is midsize then it won't take too long to blow up the balloon with one straw until you can feel the air coming out the other straw. But what if the balloon is one of those huge Mylar balloons. Well it's going to take a lot longer to blow up that big balloon until air is really flowing out the other straw.

This is just Physics. For every modded higher performance engine there's a point where the size and design of the ideal aftermarket intercooler is met and anything larger is going to take longer to fill and will contribute to additional turbo lag.

The difficulty is that IATs and Ambient temperatures provide a way to measure cooling ability of aftermarket intercoolers. But there's no simple way, without a laboratory, to measure the turbo lag created by too large of an intercooler.

Note: my first turbo car twenty years ago had twin turbos and was an absolute beast if it was already at highway speeds/higher revs. Step on the gas and it was an instant rocket. But it was brutal from standing starts and other turbo lag situations that I mentioned. It was like I could step on the gas and start counting 1-Mississippi, 2-Mississippi, etc before the power would ever come on. That's why I hate turbo lag so much and am concerned about making any mods to my turbo BMW that could contribute to turbo lag.

Turbo lag is a condition that most people cannot adequately describe and most wouldn't know if they had it. That's to be expected. Everyone gets used to driving their own car every day so they don't know the difference. They have no other reference. If they throw a bigger intercooler on their car along with a Stage2 flash tune, they will notice the extra power a lot and probably not notice if there is more lag from the bigger intercooler.

Several years ago when I was first modding my car I had to choose between two sizes of intercoolers. I went with the smaller one because I didn't want to take a chance on creating more turbo lag. A couple of friends of mine with the same engine and same Stage2 tune decided to install two different larger intercoolers. Afterwards they both insisted that they had no added turbo lag.

Months later we got together and were driving each other's cars. They both remarked that my car seemed more responsive, more drivable than their own. We weren't on a track, just local streets. We compared mods and the only difference was that they had gone with bigger intercoolers that probably gave them more lag than they realized, until they had something to compare their car to.

Hope this is helpful!

[Arkin]

Thank you all for the fill-ins.

I just did my tune-up on OEM spark plugs/Eldor coils last year. Dont want to change anything on this. Changed my charge pipe.

Currently on JB4 and want to go to BM3. BM3 will increase to 375hp. Plus the FMIC will be proximately 400hp??? is this consider stage 1+

I don't want to mess up the yearly inspections so no downpipe changes.

Changing Turbo will be expensive and may not be effective if not changing downpipe

From VRSF intercooler 5" to 7.5" is only $100. Labor is approximately $200+ so throwing that additional $100 is nothing.

[gameson]

I read your post on other thread. When you decide to get larger fmic, just let us know your experience in turbo lag going from smaller to bigger.

Originally Posted by johnung

In perfect intercooler world, an FMIC would be installed that has exactly the capacity to cool the intake air demanded by the horsepower of the modded & tuned engine.

Turbo cars come from the factory with stock Intercoolers that have the size and cooling capacity to match the stock engine. Modding/Tuning stock engines for more power causes a higher flow of hot air into the stock intercooler. This can over run its capacity to cool the air fast enough. This causes the engine to start making adjustments to protect itself which can lead to additional timing adjustments, cutting throttle and going into limp mode. The term Heat Soak is when the driver feels the engine losing power due to these adjustments because of the Intake Air Temperature (IAT) being too high entering the engine.

Heat Soak was primarily an issue at the race track where modded high performance engines needed a lot more cooling. They had to race at high revs which generated a lot of heat that made IATs go up. Big intercoolers were needed to prevent Heat Soak on the track. Turbo Lag wasn't much of an issue because race tracks don't have standing starts and low rev driving like daily drivers on the street.

What you may have read is that installing an intercooler with much more capacity than is really needed, can potentially cause delay or turbo lag. That's basically the amount of time that it takes from when you put your foot down on the accelerator until the engine can build up enough boost pressure for the driver to feel the power come on.

This delay would be most noticeable when accelerating from a standing start like from a stop sign or when waiting at a traffic light and it turns green. Other situations might be suddenly trying to pass another car or when trying to accelerate to merge onto a freeway.

The air intake system path on these turbo cars consists of three pieces:

1) the Turbo To Intercooler (or TIC) Pipe that delivers the hot air to the Intercooler,

2) the Intercooler itself that cools the hot air,

3) and the Charge Pipe (CP) that delivers the cooled air to the engine.

The TIC and CP pipes are pretty much the same size whether stock or aftermarket. It's the Intercooler that has various aftermarket options for both volume and cooling core specifications.

A car manufacturer like BMW has engineers to design and test to determine the perfect stock intercooler. In the aftermarket the most common tool is the same as been used by trackers for decades, the Intake Air Temperature. It's pretty easy to take engine logs from Wide Open Throttle (WOT) runs in 1st to 4th gear. The values of the IAT and the Ambient temperatures make it easy to judge how well the Intercooler is cooling the hot air being thrown at it by the modded engine.

So at some point the correct size & design of an aftermarket Intercooler will adequately cool the maximum that the modded engine can throw at it. A potential turbo lag issue may be created if a much larger intercooler is used than is needed to keep IATs down to a working modded engine level.

One analogy might be a balloon representing the Intercooler and two straws at either end representing the two pipes. Well if the balloon is midsize then it won't take too long to blow up the balloon with one straw until you can feel the air coming out the other straw. But what if the balloon is one of those huge Mylar balloons. Well it's going to take a lot longer to blow up that big balloon until air is really flowing out the other straw.

This is just Physics. For every modded higher performance engine there's a point where the size and design of the ideal aftermarket intercooler is met and anything larger is going to take longer to fill and will contribute to additional turbo lag.

The difficulty is that IATs and Ambient temperatures provide a way to measure cooling ability of aftermarket intercoolers. But there's no simple way, without a laboratory, to measure the turbo lag created by too large of an intercooler.

Note: my first turbo car twenty years ago had twin turbos and was an absolute beast if it was already at highway speeds/higher revs. Step on the gas and it was an instant rocket. But it was brutal from standing starts and other turbo lag situations that I mentioned. It was like I could step on the gas and start counting 1-Mississippi, 2-Mississippi, etc before the power would ever come on. That's why I hate turbo lag so much and am concerned about making any mods to my turbo BMW that could contribute to turbo lag.

Turbo lag is a condition that most people cannot adequately describe and most wouldn't know if they had it. That's to be expected. Everyone gets used to driving their own car every day so they don't know the difference. They have no other reference. If they throw a bigger intercooler on their car along with a Stage2 flash tune, they will notice the extra power a lot and probably not notice if there is more lag from the bigger intercooler.

Several years ago when I was first modding my car I had to choose between two sizes of intercoolers. I went with the smaller one because I didn't want to take a chance on creating more turbo lag. A couple of friends of mine with the same engine and same Stage2 tune decided to install two different larger intercoolers. Afterwards they both insisted that they had no added turbo lag.

Months later we got together and were driving each other's cars. They both remarked that my car seemed more responsive, more drivable than their own. We weren't on a track, just local streets. We compared mods and the only difference was that they had gone with bigger intercoolers that probably gave them more lag than they realized, until they had something to compare their car to.

Hope this is helpful!

[johnung]

Originally Posted by Arkini

Thank you all for the fill-ins.

I just did my tune-up on OEM spark plugs/Eldor coils last year. Dont want to change anything on this. Changed my charge pipe.

Currently on JB4 and want to go to BM3. BM3 will increase to 375hp. Plus the FMIC will be proximately 400hp??? is this consider stage 1+

I don't want to mess up the yearly inspections so no downpipe changes.

Changing Turbo will be expensive and may not be effective if not changing downpipe

From VRSF intercooler 5" to 7.5" is only $100. Labor is approximately $200+ so throwing that additional $100 is nothing.

A Stage1 tune by definition means that everything else is stock. There is a caveat to that with the F30 N55 engine. The poorly designed/shaped charge pipe will most likely break if not upgraded. FTP and Evolution Racewerks make high quality aftermarket charge pipes.

I started 3+ years ago with a JB tune on my car. Bootmod3 is so much smoother and more powerful.

A Front Mounted Intercooler (FMIC) upgrade is desirable with a Stage1 tune, and required for a Stage2 tune.

A Stage2 tune also requires a high flow catted or catless downpipe. That's because the higher boost pressures of the tune create higher backpressure that could damage the turbo. A free flow DP reduces this backpressure.

There is a much greater performance increase by going from stock to a Stage1 tune, than from going from a Stage1 tune to a Stage2 tune. So don't believe the "ya gotta go to Stage2" comments that you'll read. A Stage1 tune is plenty powerful.

Do you have the earlier N55 PWG engine or the N55 EWG engine that began going into the F30 335i's with the July 2013 build dates. Enter your VIN into realoem website and see your build date. Generally when you tune a N55 EWG you can get up to 30hp more than an n55 PWG. But it's no big deal.

For an N55 Stage1 tune or even a Stage2 93 octane tune, a high quality 5" intercooler is fine. A big race IC would be overkill. For years I've run my N55 EWG Stage2 93 Octane tune on a Wagner EVO1 intercooler with excellent results. Excellent cooling and very quick response and drivability.

My friends with the same engine and tune definitely have more lag in street driving with their giant race intercoolers. They made the choice for better cooling at high revs when they drive their cars on the race track, but less responsiveness in low rev driving and from standing starts in daily driving. I don't track. I get my driving fun on the street. 😀

Hope this helps!

[johnung]

Originally Posted by gameson

I read your post on other thread. When you decide to get larger fmic, just let us know your experience in turbo lag going from smaller to bigger.

I will definitely post about my intercooler upgrade experience. My car is a real beast now with fueling upgrades and running Bootmod3 FlexFuel MultiMap tunes with E85 fuel. So I'm overwhelming my first upgraded intercooler and now need an FMIC with more cooling capacity.

I know that I could solve my cooling issues by installing a big race intercooler. But as I've posted earlier, I have a real hatred for turbo lag in my daily driver. I'm not upgrading my turbo and running 600hp or anything like that. So I'm not convinced that a big volume race intercooler won't be overkill and introduce added turbo lag.

Cooling is something that can be quantified pretty easily by recording and analyzing engine logs with IATs and ambient temperature comparisons. But turbo lag measurements require more sophisticated lab instruments. So turbo lag becomes a more qualitative evaluation, like a butt dyno, but for intercoolers. 😀

I thoroughly evaluated FMICs almost four years ago before making my choice. Now the intercooler market has changed a bit. There seems to be mostly two extremes: smaller upgrades that probably work fine for around 400+ horsepower, and larger race intercoolers that probably handle 500-600hp just fine.

I'm thinking that for 450-500hp (where I'm guessing that my engine is now at before upcoming dyno testing), the ideal FMIC may be something somewhere in the middle. I don't know if it exists at the moment. I'll take any suggestions.

Many of the intercoolers on the current market are cheap China made models without much development or testing behind them. They are sold on marketing and price. Many are exactly the same and made in the same factory in China.

I was actually encouraged the other day to read the post at the link below. It appears the Pro Tuning Freaks/Bootmod3 actually did a lot of development on their recently released FMIC in regards to both cooling and flow (which reduces lag). I'm hoping to test the PTF FMIC to see how it meets my engine's requirements. I don't expect it to match IAT performance of the race intercoolers and that's okay. I'm curious to see if it does an adequate IAT cooling job while maintaining responsiveness and drivability.

Any comments/thoughts are welcome.

Here is link to PTF discussion on their new FMIC
https://f30.bimmerpost.com/forums/sh....php?t=1862739

[AmuroRay]

There isn’t really any R&D behind any core. They use the same cores for all their cars/makes and weld different end tanks to them.

If you’re really concerned with lag, upgrade your DV (which you should already do because of the boost you’re running) and intake (M2 lower box with a dry filter or something like the CTS) both of those will have a positive impact on your throttle response and help you hold power better.

Edit:

I’m not sure I understand the appeal of the PTF Intercooler. It has a lower external fin pack density (lower than MAD, VRSF, and BMS) it’s just as big and it’s more expensive.

The external fin pack has nothing to do with the internal fin pack density. So believing you’ll have less lag because there are less fins on the front is misguided and wrong.

It also saw a +28 increase on a short pull on the only real world test we’ve seen. Im not impressed by it, but it’s your money.

[gameson]

What valve is DV?

Originally Posted by AmuroRay

There isn’t really any R&D behind any core. They use the same cores for all their cars/makes and weld different end tanks to them.

If you’re really concerned with lag, upgrade your DV (which you should already do because of the boost you’re running) and intake (M2 lower box with a dry filter or something like the CTS) both of those will have a positive impact on your throttle response and help you hold power better.

Edit:

I’m not sure I understand the appeal of the PTF Intercooler. It has a lower external fin pack density (lower than MAD, VRSF, and BMS) it’s just as big and it’s more expensive.

The external fin pack has nothing to do with the internal fin pack density. So believing you’ll have less lag because there are less fins on the front is misguided and wrong.

It also saw a +28 increase on a short pull on the only real world test we’ve seen. Im not impressed by it, but it’s your money.

[AmuroRay]

Originally Posted by gameson

What valve is DV?

Diverter valve. I have the Turbosmart plumb back version.

[gameson]

Originally Posted by AmuroRay

Diverter valve. I have the Turbosmart plumb back version.

Expensive? What are the options? Can this stock oem part fail easily with bm3 stage 2 tune? Thanks.

[AmuroRay]

Originally Posted by gameson

Expensive? What are the options? Can this stock oem part fail easily with bm3 stage 2 tune? Thanks.

It’s about $2xx on Keis Motorsports, they have a plumb back or a conventional ‘vent to atmosphere’ options. The plumb back would be better for throttle response, the vent to atmosphere better for sound. The OEM part can leak, and possibly not hold boost as well

Mine never gave a code, but since upgrading I do hold boost better and have better throttle response. The stock M2 comes with the N20s diverter valve, which apparently hold more boost

[thejeremyman9]

Originally Posted by gameson

I read your post on other thread. When you decide to get larger fmic, just let us know your experience in turbo lag going from smaller to bigger.

I went from stock IC to 5'' stepped IC to race is. There is no lag when you upgrade to a race IC. As Amuro alluded to, if you want to "reduce lag" or improve throttle response, you need to optimize the intake/inlet system. I recommend an inlet like MST v2, MPPK lower airbox bottom, and a dry drop in filter.

I've done numerous tests both qualitative and quantiative on different intake setups and that is my #1 recommendation. IF you want noise, i would say get CTS, but it provided no qualitative improvment in driveability or really any discernable difference in the data with my setup. For example, intake testing: https://f30.bimmerpost.com/forums/sh....php?t=1765289

Everyone seems incredibly paranoid about turbo lag when upsizing their IC. For a stock turbo car, especially once with inlet/intake upgrades as i mentioned, the difference in IC volume is negligible in terms of the time it takes to fill that air and what you would perceive as turbo lag when driving. I floor my car from a dead stop at idle all the time (no LC) and there is no lag, it surges forward nearly instantly.

It's very difficult to try and quantify turbo lag in datalogs, but look at these for an example:

Log with 5'' IC right before race install: https://datazap.me/u/thejeremyman9/3...&data=4-5-7-17

Log with race IC right after install: https://datazap.me/u/thejeremyman9/3...&data=4-5-7-17

The RPM where i go WOT is very similar in both logs (~2200 rpm) and you can see that with the race IC, the slope of the boost curve is actually steeper (builds boost faster) and it takes the same or less time from going WOT to reach boost target... Not sure what other evidence you guys want.

Edit: FWIW im still on stock DV. I may one day do a test like i did for intakes, but not in a rush at the moment.

[AmuroRay]

Originally Posted by thejeremyman9

I went from stock IC to 5'' stepped IC to race is. There is no lag when you upgrade to a race IC. As Amuro alluded to, if you want to "reduce lag" or improve throttle response, you need to optimize the intake/inlet system. I recommend an inlet like MST v2, MPPK lower airbox bottom, and a dry drop in filter.

I've done numerous tests both qualitative and quantiative on different intake setups and that is my #1 recommendation. IF you want noise, i would say get CTS, but it provided no qualitative improvment in driveability or really any discernable difference in the data with my setup. For example, intake testing: https://f30.bimmerpost.com/forums/sh....php?t=1765289

Everyone seems incredibly paranoid about turbo lag when upsizing their IC. For a stock turbo car, especially once with inlet/intake upgrades as i mentioned, the difference in IC volume is negligible in terms of the time it takes to fill that air and what you would perceive as turbo lag when driving. I floor my car from a dead stop at idle all the time (no LC) and there is no lag, it surges forward nearly instantly.

It's very difficult to try and quantify turbo lag in datalogs, but look at these for an example:

Log with 5'' IC right before race install: https://datazap.me/u/thejeremyman9/3...&data=4-5-7-17

Log with race IC right after install: https://datazap.me/u/thejeremyman9/3...&data=4-5-7-17

The RPM where i go WOT is very similar in both logs (~2200 rpm) and you can see that with the race IC, the slope of the boost curve is actually steeper (builds boost faster) and it takes the same or less time from going WOT to reach boost target... Not sure what other evidence you guys want.

Edit: FWIW im still on stock DV. I may one day do a test like i did for intakes, but not in a rush at the moment.

I’ll just point out that the CTS actually had positive fuel trims indicating it made additional power over the M2 lower box. There are also dunks of open intakes making more power than the stock box - even the M2 box. Take it for what it’s worth