Gruppe M Air Intake for a 1995 Ferrari F355 Spider M2.7

My GruppeM is Kevlar and not carbon fiber, but the first thing I noticed after I installed it how much cooler the air box was compared to the stock metal box. Also, when you put it on a dyno, don't you need air flowing through the side vents into the air box to really see the effects of the GruppeM? Did you have a fan blowing air into the vent with the stock box and then the GruppeM?

 

I got mine brand new in Japan, where I have an office. The car already had a heat shield between the exhaust and the air box but it looks like the current heat shield is not as good as the one you're talking about.

At any rate, the Gold-reflective-coating has now been applied, so this should result in cooler operation. And in addition, I'm having new intake runners fabricated from Aluminum since the current corrugated flexible duct that feed's the air box is not as efficient as a proper aluminum pipe. After the pipe is done (another 2-3 days), I'll have the car Dyno'ed again just to check the differences. Hopefully, a lot of the lost top-end power will be restored...

BTW - the top-end power loss was serious: 344 rwhp down to 328 rwhp : so a loss of 16 HP. Besides the heat affect and poor intake runners, another cause of this loss at the top-end is that the inlet duct behind the filter element is flat and has no bell mouth or velocity stack, which is A VERY POOR DESIGN. I will be giving this feedback to GruppeM in Japan as well but i doubt they'll do anything about it.

Fortunately, the guys handling the job in the UK are very, very good. Advancedmedyno.com does the Dyno work and Damax.co.uk takes care of the car. Both are within 5 miles of Silverstone, where the car does a lot of track days .

-- Atul

 

Bob - the air box is cooler only at low-revs and the temperature depends on proper heat insulation. With the new reflective-coating, the air box will be cooler. During the Dyno run, temperature tends to build up (there are several runs) and this heated up the air box fairly significantly. Just building the box with Carbon/Kevlar does not mean it will not heat up. Give it enough heat and it will heat up!

I will soon post pics of the Dynographs "before GruppeM" and "after GruppeM". There's a slight problem with the "after" graph since when these guys generated the graph they had used different correction factors and different units (N-M instead of ft-lbs for torque) because they'd previously tested a Formula-E car. The corrected Dynograph for the "After GruppeM" run will be posted later today or on the weekend as soon as the AdvancedMeDyno folks get it to me.

-- Atul

 

Hi All: attached is the Dynograph for the run with the standard Airbox. The graph shows a blue line and a dotted red-line. The dotted red line is the unoptimized Motec ECU and the blue line is the final, corrected/tuned Motec ECU. As you can see from the graph, the final power figure went to 344.42 rwHP with the optimized Motec run, from the 324.99 rwHP of the unoptimized Motec.

This graph was generated with the STOCK Airbox, running K&N filters. The car is a '98 2.7 factory challenge car with the following mods: Motec M84 ECU + Gasflow/ported heads (done by DTM Power : dtmpower.com). I'm not sure whether the gas flow heads added any extra power though!

I shall next post the dynograph with the GruppeM Header installed. You'll see that the bottom-end went up and the top-end went substantially DOWN. More on that shortly.

-- Atul
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Atul. What would be really interesting is if you tried a foam type filter vs the K&N type filter. It should flow more air and over a longer period of time because dust won't get clogged up in the tight grooves of the K&N type filter.

ITG is reputable in the racing scene for their foam type filters and also located in the UK. They actually make one for the 355. Perhaps they can even make you a cone type in a similiar size to your Gruppe M K&N filters to use with your Gruppe M box.

http://itgairfilters.com/search/

 

... And you mean velocity stack behind the filter like this?
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Foam filter vs K&N ( Gauze filter)

Foam Filter Q&A, why they are the best. » PERRIN Performance Official Blog

It's very easy to improperly over oil the K&N's, which often leads to messing up the MAFs.

 

Hi All:

So finally, here's a Dynograph with the GruppeM air box installed. To the best of my knowledge, this is the *first* dynograph for the 355 with the GruppeM air box installed. There have been plenty of claims about added power, 'seat in the pants feel', etc. etc. A lot of this is explained by the attached Dynograph.

BEFORE you read the graph, please note that there's a correction factor involved in comparison with the Dynograph of post #54. In this new dynograph (the 'with GruppeM air box' graph), the units for the torque measurement are N-M, rather than ft-lbs. And there was also another correction factor involved which makes the Horsepower figure look a bit too low. This is because the Dyno shop had just taken a Formula-E car off the dyno and in their hurry had forgotten to change some settings.

In this new "With GruppeM Install" graph, the BLUE line now indicates the 'original' graph (i.e. with the OEM air boxes) and the dotted RED line indicates the figures with the GruppM air box installed. Here are the findings:

1. At the low-end, at about 4,000 RPM, there is a TORQUE BOOST from 212.37 N-M to 233.7 N-M. It is this TORQUE BOOST that makes most people feel that the GruppM air box is 'adding a lot of power to my 355'. So the initial feeling after installation will always be "WOW - this thing's real cool".

2. At the top-end, there is a power REDUCTION (especially between 7000 and 8300 RPM) from an indicated 324.87 rwhp to 317.44 rwhp. However, because the 'dyno correction factor' was not applied before the dyno-run, these two numbers should actually read : 344 rwhp to 328 rwhp. I hope this is clear to everyone: the actual number at 8200 RPM went DOWN from 344 to 328 rwhp : a LOSS of about 16 HP.

Reasons for top-end power loss: there are three primary reasons for the loss of top-end power:

1. Heat buildup: The GruppeM airbox is right above the exhaust and unless there's substantial heat shielding, the gases in the air box get heated up and so produce less power obviously

2. Intake Runners: The intake runner tubes into the air box need to be wider and ideally need to be made of Aluminum for better airflow

3. Trumpets: tje GruppeM airbox internal design seems to be FUNDAMENTALLY FLAWED. The comment from my tech, Josh Jacob is "the inlet duct behind the filter element is flat and has no bell mouth or velocity stack, i would like to fit two trumpets one behind each filter, i believe this will increase the flow and help in the high rpm, i am sure you can appreciate its R&D but the laws of physics say it should work".

Attached is the Dynograph. A picture of the GruppeM internal design flaw will be uploaded in the next post.

-- Atul
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I'll certainly give it a go (after the current 'development' work!) but I doubt it's the filter. There's a pretty fundamental problem with the GruppeM design which shows up at HIGH RPMs. Most drivers putter around at between 3000 and 6000 RPM for the most part. They don't operate between 7000 and 8200 RPM very often. However, when one is on a track like Silverstone, a lot of time is spent between 7000 and 8000 RPM and with a powerless of 15 HP in that range, one can really feel the difference in lap times.

But all of this is not relevant to the GruppeM business: GruppeM DOES deliver low-end Torque and this is what most drivers feel. Hence the comments "I felt the power right away", "my seat-of-the-pants dyno says there's 10-15 HP there". What people are feeling is the added low-end torque.

The picture of the internals comes next...

-- Atul

 

Hi Folks:

So finally, here's a picture of the GruppeM internal design. As the tech explained "the inlet duct behind the filter element is flat and has no bell mouth or velocity stack".

One needs to fit two trumpets one behind each filter which SHOULD (in theory) increase the flow and help the high rpm airflow, which is currently being suffocated.

To be honest, I"m amazed how GruppeM did not figure this out before, and also why so many techs/mechanics installing these GruppeM air boxes haven't figured this out. For an experienced Ferrari tech, this stuff should be second nature, but then I suppose it's more related to the development of Racing engines. My two techs: Damax (damax.co.uk) and Advnaced Motrosport and Engineering (Advancedme.co.uk) are both experienced in racing (Group C for Damax and various formulas for AdvancedMe) immediately pointed this out.

So I'm posting these findings with a view to helping all GruppeM users. Bear in mind, however, that we have note yet *tested* the proposed velocity stacks/Trumpets, though we're sure they will help resolved the high-end power problem since it seems to be fundamentally airflow related. Once this is verified, we will have a proper way to ensure that the GruppeM Airbox does indeed increate power through the range.

Hopefully, this should put to rest the whole debate about GruppeM: yes, it does produce some low-end torque, but it reduces top-end power in a 2.7 car, provided the 2.7 OEM air boxes run K&N filters. Everyone ought to be aware of this. MOST 355 owners do not drive a lot between 7000 and 8200 RPM so they never really see the problem with the GruppeM air box. This is probably the reason why GruppeM decided it was not worth adding the Trumpets and velocity stacks: why spend more money when the user isn't going to use the part at that level 95% of the time.

... though they forgot the last 5% of users .

-- Atul

 

Sorry - there's a problem in uploading the image. Perhaps its a quota issue. I'll have to check

-- Atul

 

Hi All: Here's the photo of the (flawed) internal design of the GruppeM Airbox. (The previous upload failed due to a size restriction).

As you can see, the inlet duct behind the filter element is flat and has no bell mouth or velocity stack. Thus two trumpets need to be fitted, one for each filter element...

-- Atul
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Hi All: Now finally, here's the proper "before vs after" Dynograph with all corrections applied.

The Blue line indicates the torque and HP *before* the GruppeM air box installation. i.e. with the original twin 2.7 Airboxes.

The dotted red line shows the torque and HP curves *after* the GruppeM Box was installed.

As one can see, there's clearly more torque between about 3700 and 4500 RPM and this will make the car feel more powerful at 'everyday' speeds around town and while pulling out of slower corners at the racetrack.

Between 4500 and 6500 RPM, the GruppeM is about the same as the OEM air box(es) in terms of power and torque.

However, at real 'race speeds', between 6500 and 8300 RPM, the GruppeM power drops off fairly linearly compared to the OEM air box.

Note that this run was done without the hard intake liners (which are now being fabricated) and also without the gold-reflective coating to reduce the heat in the air box. With these two changes, we will Dyno the car once again. Finally, the flawed internal design of the GruppeM box will be corrected with the proper Velocity stacks and Trumpets and hopefully this will lead to a proper gain in power right across the power band!

Hopefully, this lays to rest all the back and forth arguments about Dynographs for the GruppeM. Note that the car has a Motec M84 chip, gas-flow heads and is a /98 2.7 Challenge car.

Don't we just LOVE our 355's .

-- Atul
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Hopefully you can Dyno each of the changes so we can see which change has the greatest effect in power.

 

When I first received the Gruppe M setup and analyzed it, my first initial impression was I could probably build/put together a better setup. I too noticed the lack of a velocity stack. The picture I posted is a Saclam intake system for the 355, which clearly has nice properly made velocity stacks. Adds weight, but it is what it is.

Gruppe M also uses aluminum as shields with a bit of fabric padding in some areas. I have no idea what the fabric is. Doesnt seem like kevlar to me. Inconel padding would've been more appropriate. Aluminum also conducts heat big time, so why would someone use it to shield against heat? The shields should be made of carbon fiber w/ inconel padding. The gold reflective shielding is a great idea. I believe Tim has some padding solutions that can be placed inside the boxes.

The gauze K&N filter is not the problem you are having at the moment. I was simply implying that you can make more power once you get the other problems corrected using a foam type filter, which flows more air and will clog less than the K&N filter over time.

 

Also. Can you tell us more about your tune? What octane are you running?

 

And here's the link to the *first* U.S dyno test on the Gruppe M

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/65751-355-gruppe-m-system-3.html

 

Nice

Money for nothing get your chicks for freelol

 

Ugh. No surprise at a power loss with that design.

 

Just curious, is it possible there'd be a significant difference in the graphs if the car was a 5.2 rather than a 2.7?

Considering the intake design is so different in the two versions, and looking at the graphs Ken posted, is it possible that the Gruppe M intake is much more worthwhile to 5.2 cars than 2.7?

I'm interested as I've been considering one of these intakes for a while, but I won't bother if there really isn't much to gain.

 

Yeah, I was going to mention... my car is 5.2 and my GruppeM looks nothing like that internally. Mine is a wide-open round cavern behind the filter on each side. I would go out and take a pic, but it's like the surface of the sun outside right now. heh.

 

Thanks.

When I've got more time I intend to buy a Gruppe M for my 5.2 F1 car on the basis that I'll do an immediate before and after dyno, and if there's nothing in it I will send it back (and get my money back) but if the gains are significant (as claimed) I'll happily be an advocate for the mod.

We'll see if they will go for it.

 

This may be a stupid question but the effect of a ram air intake is forced air through the side vents into the air box. This would happen in real life when the car is moving. Are you simulating this on the dyno with fans? If not how can you gage the performance of the stock or GruppeM intake?

 

^^Kind of hard to figure out. Not much ram air effect in 1st gear but I suspect a bit at the top of 6th

If the test was ran the same with both inductions it should still show if an induction shows promise (or not).

 

I would think the vent below the window would have a fair amount of air flowing through it into the air box at speed. How do you test this effect on a stationary car when the effect is realized when the car is at speed? Cars are tested in wind tunnels to test airflow into ducts, aerodynamics etc.to simulate a cars movement through air. the stock intake may be better than GruppeM but how do you know without simulating actual driving conditions-- air flowing into the duct into the box. One version may flow and handle moving air better than the other.