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

I completely understand what you are saying but it's not a constant, it will increase with speed.

What I'm saying is if both the stock airbox and the gruppe m were dynoed with no fans into the vents it's a fair test.

If it loses power at whatever barometric pressure is I don't think it would for any reason then surpass the function of the stock airbox with a slightly higher inlet pressure.

Really I don't see how it could be any good with no inlet bell and just a flat squared off inlet with sharp edges.

JMO

 

One last point. I have a GruppeM and it may not be as good as stock. My understanding was it handled the air flow coming in the side vents better. This effect is not constant, I would assume it increases with the speed of the car. When Pontiac had ram hoods if the effect of that hood was tested at idle, one might come to the conclusion it had no effect.

All these intakes call themselves "ram air intakes". Maybe the name is just marketing and hype but it seems you can't judge the effect without simulating air ram movement. Maybe this air movement would show the GruppeM is worse with simulated air movement. Does anybody even know how effective the window vent is?

 

The stock air boxes are fed by the same tubes leading to the rear windows and the path seems unobstructed. (so not sure how GruppeM would be more efficient in that respect).

Just saying that if the stock setup indeed makes more power on the dyno with no extra airflow into the vents, I think it's reasonable to think it would do even better at speed as it's being fed air in the same manner.

You're fairly close to some dragstrips Bob. Could always make a few runs with stock and GruppeM to see if there's any difference in trap speed. That would tell you if one or the other is better at speed.

 

Ive been told that the design from the wind tunnel on the 355 comes into play at 80km and up and I believe this includes the air intake.

 

Anyone wanna buy my OEM replacement K&N Filters? Brand new. Never used/installed. $125 shipped!

Ken

 

Bob: the dynoshop did precisely this today - they forced air in at 70 MPH and that actually *reduced* the power. So the simulation of 'an air box at speed' was done and it does not help any.

The good news is that all the new changes (heat-reflecting coating, hard liners and velocity stacks) resulted in power improvements and I will soon be posting the new dynograph.

-- Atul

 

Bob: the test was done under the same exact conditions with in both cases. So its a 'like for like' test. There was air going into the vents (and plenty of it) since there was a huge suction fan at the back of the shop pulling out air (else we'd have all suffocated from the fumes like people have done before - I'm not saying where or when!).

-- Atul

 

Now here's the update on the GruppeM intake after the following mods:

1. Hard liner intakes: the intake pipes were custom-made from Aluminum to make the intake airflow smoother

2. Heat-reflective gold coating to the underside of the GruppeM intake.

3. Heat-reflective gold coating to the small pipe that takes the air from the GruppeM box to the main induction chamber of the engine

4. The installation of Velocity checks.

I wanted the check to be done in two steps : the first with 1/2/3 and then with 1/2/3/4. Unfortunately, the Dyno guys decided to just do one check, with all four mods. So we will not know precisely what caused the power to go up.

The good news is that with these four changes, power goes up from 332.77 rwhp to 351.04 rwhp. So in essence the GruppeM box *with these mods* is a little more powerful than the stock 2.7 box, assuming one has a Motec ECU installed as well.

And here are some pics:
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Nice work! I would try an even more bell mouth shaped velocity stack if you can find something that fits.

 

If one notices carefully, one will see that the original 'low end torque gains' are now lost and basically the modified GruppeM intake provides marginally greater power than the stock 2.7 intake.

Of course, these figures cannot be mapped to a 5.2 system. They should only be used in the comparison of a 2.7 stock vs. GruppeM intake.

The overall gain is about 6 BHP. The tests were done under 'like for like' conditions (same airflow, same temperature conditions). The heat-reflective coating keeps the temperatures about 18 deg C cooler, which is quite significant. It would seem that the Velocity stacks have helped as well, though we do not know for sure since the test was not done without these velocity stacks/Trumpets.

The test was performed on a relatively hot day, so one might expect more power gains overall (from both intakes) on a cooler day, which we fortunately have both at Silverstone and at SPA, as well as at other UK/European racetracks!

But in all honesty, if one has a 2.7 car, one might be better off just adding a much better heat shield above the exhaust and adding heat-reflective coating. That might result in even more power. Plus, if one installs velocity stacks in the OEM 27 system one could potentially get even more power. These are development test that need to be carried out.

For now I'll keep the GruppeM system and do a few track days. Will report 'seat of the pants' driving results next week sometime.

-- Atul

 

Shell premium : 99 Octane here in the UK.

-- Atul

 

Thanks Atul

 

Thanks for the good documentation of your design changes. Did you add any ignition advance with your Motec tune?

 

Bob - I'm not completely sure whether ignition advance was added or not. The guys at Advanced Motorsport here at Silverstone are very good with the Motec programming and we're making many changes dynamically. It was quite amazing to see the power of the e vine being optimized in real time.

I'm using the entry-level Motec M84 ECU. With the M800, one can add several new features including "Drive by wire". With DBW, the ECU will automatically set the throttle at the proper opening for a given RPM. FOr instance, if at 3500 RPM your torque is high, then even if you go to full throttle with your foot coming out of a corner the ECU will only open the throttle as much as required to reach the optimal torque (as determined by the 'map' stored in the ECU). Very cool. Not getting that done right now but it can be done ...

The next mod is likely a tuned exhaust system (separate exhausts for each bank of the V8), which should likely add another 12-15 HP.

Beyond the exhaust, increased power gets expensive (intake system mods, etc)

-- Atul

 

Thanks. Your car sounds fantastic. I have piggy back computers on mine that can change the timing and fuel and it really does make a difference in power and drivability when these cars are tuned. People say Ferrari did not leave much to tune, but I don't think that is true. Post some pics of you car if you can, love to see it.

 

Your 100% correct. These things are so de-tuned for street driveabillity and emissions it's scary.

My 348 ch is now faster then my stock 355 but not the 355 CH LOL

More fuel, spark pull more air.

 

Hey Atul,

Thanks for the feedback. I am going to assume you are running challenge exhaust at the moment? A 360 rwhp light weight 355 would be a blast to drive.

 

Atul. What is the diameter of the Gruppe M K&N Air Filter? It seems to be smaller than the one offered for the Gruppe M 5.2 system, which is about 200mm in diameter.


And for those of you who already have the 2.7 Gruppe M system, you can replace your K&N filters with an ITG Conical Foam Filter, which already has a built-in trumpet. Just weld a flange onto the filter and you should be able to clamp it up to your Gruppe M system. Thank me later

http://itgairfilters.com/category/maxogen/conical-air-filters/

 

Hi everybody: about the 'tuning' aspect of the car, well there's always a fair amount one can do but there are increasing compromises with each stage. I'd say that just moving to a motec ECU is worth about 20 rwhp with the optimized fuel and ignition timing, since the optimization is specific to your particular car (and not a general chip, like the stock 2.7 or 5.2 ECU for all cars). However, there are drawbacks : cold starting is worse because the Motec requires one to turn the crank twice the number of times compared to the Stock chips. This is because the stock chips both have two crank sensors while the Motec has just one. And if the Motec crab sensor gets dirty (the crank sensors are installed outside the crankcase for both Motec and Stock) then your engine stops!!

This in fact happened to me en route to SPA early August - I drove through rain (it's Belgium!) for two hours and approaching SPA, 25 miles away, the engine died. Had to flatbed the car to a garage. The next morning, sim walkways dry and clean, the engine magically started up! So I carried on to SPA. Now wha stock 2.7 or 5.2, chance of this happening are very low because of the two crank sensors .... So I hope everyone sees the compromises here ...

The tech says an exhaust change (no change to headers other than to go from 4 --> 1 --> 2, to 4-1-1, so each bank is fully I dependent of the other) should get another 10-15 rwhp and likely better bottom end torque. That should bring it up to about 360-365 rwhp, which will make the car A lot more exciting on track. It's already an absolute blast on the road. A bit crazy buy amazing fun.

I'm at Silveretone Sept 6 and will take and post pics then.

Cheers, -- Atul

 

Autl,

Any updates to how the car was on the track?

 

Would love to see some videos from inside the car of it being ran as well.

360-365rwhp in a 355 would be fantastic.

 

Hi Everybody:

It's been a long winter in the UK. I ran the car Feb 14th at Silverstone last month but it rained like crazy and so obviously could not push too hard. Great practice on wet tires though... and good learning with two spins!

The Motec was remapped yet again and the midrange improved significantly. The car was then re-dynoed with the new exhaust (two separate banks : 4-1-1, flatter but still very good sound, almost like two four-cyl engines). Importantly, the intakes of the velocity stacks were polished and smoothened to decrease air turbulence. My Tech said this was critical in improving power.

Result: a proper 370 BHP at the rear wheels measured on the rolling-road (a different dyno than the last time), which mapped to a shown 444 BHP at the crank, but after corrections for ambient temperature and pressure this number was remapped to 420 BHP at the crank. I ran the car again on Feb 24th at Abingdon as part of an all-day training session (Abingdon an airfield near Oxford, UK, where they have trackways and training sessions). The car felt significantly more powerful. I can't wait to try it again at Silverstone.

Next tests: March 22nd, Silverstone and then March 25/26 at Spa Francorchamps! Will post results/information. Hopefully, it stays dry.

The car now also has a new, thicker front antiroll bar and remapped Ohlins TTX36 dampers front and rear. So it should be a fun drive around these iconic circuits...

Cheers,

-- Atul

 

The car as a Racelogic Video-lite system installed so we will take and post video as well, from both Silverstone and SPA...

-- Atul

 

Cannot wait for the videos!!

 

Impressive! Please tell us more about your TTx dampers. Who put it together for you? What spring rates did you choose?