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

The dampers are, as with everything else on a 355 Challenge, quote a saga.

This was my first ever 'custom damper build'. I got the bright idea of *saving money* (on a 355 .... Ha Ha Ha!) by getting the dampers fabricated in California (against the advise of my tech... whom I've now learned to respect a lot more). Performance Shock, Inc at Sears Point had them advertised at about $1000/damper. To make the long story short, we sent them the specs (from the UK). The damper build ended up costing about $9000+ with all the parts, top-eyes etc. Trouble was that they had a regular 355 'test car' for the dampers and we ended up with the incorrect lengths on the dampers (too long according to the then mechanic). Spent another 1500 quid getting them modified and then switched mechanics. The final tech (Damax, at Brackley, this domain for sale!!, who still runs the car) said they were then too short . More $$$$. The dampers were FINALLY set right by BG Motorsport at Silverstone. Lesson learned: always build the dampers some place close by where you can send them the pattern dampers from your car and where your tech can actually meet the Damper engineer.

The dampers are TTX36 ILX (inline dampers) because the piggybacks do not fit the 355. The trouble with all the lengths was that the inline dampers have the reservoir inside the shaft and this reduces the compression and rebound damping proportionately compared to the piggybacks. My 550 Maranello has the Piggybacks (these were built by a different Ohlins engineer locally in the UK... and then 'fixed' again by BG Motorsport .

Now here's the issue with the TTX36 ILX dampers for the 355 Challenge (or regular 355 - they use the same wishbones). The lower part of the damper canister does not clear the wishbone completely, and this means an additional 10-15mm of compression damping is LOST if one wishes to use the stock wishbones. So we decided to SHAVE ABOUT 5MM OFF THE LOWER WISHBONE INSIDE EDGE to allow more clearance and this did the trick. Of course, Robin Ward at Damax (he's a Group C racecar mechanic so knows all about racing) reinforced the wishbone again to ensure strength.

We're using 2200 LB springs up-front and 700 at the rear. Proper Ferrari Challenge setup. The Dampers weree matched to these springs by Ben at BG Motorsport and set up on the Damper Dyno. We FINALLY then had the proper set of Dampers for the 355.

One more thing: The rears were too long so we inverted the mounts to accommodate the extra length. That's the easiest solution.

Performance: from the test at Abingdon, they are utterly awesome. The car tracks beautifully, handles incredibly well. Its got the fast-steering rack so less than a turn lock to lock - proper race stuff. An absolute joy to drive. MILES MILES MILES better than the OEM Bilsteins and all that "automatic self-leveling rubbish" that Ferrari built...

The TTX36 ILX dampers are expensive but are ALMOST as good as the TTX40 Mk. II Dampers. They transform the car and are well worth every penny. Just be sure to work closely with the damper engineer and your tech and have them talk to each other to ensure the build goes well.

The dampers on the car are 3-way adjustable: Bump, Rebound and High-speed bump.

Another thing: we had new antiroll bars custom built: stiffer at the front and slightly softer at the rear. The super stiff front-end helps the 355 Challenge. Take my word for it and Robins as well: He raced this same car in 1998/9 and won the local Ferrari Challenge championship.

If anyone's interested, I can ask Robin and Ben for all the data on the dampers (lengths of the rods at both ends, compression/rebound strokes, droop length, etc.).

Next project: I have a 458 Italia which, for all the rubbish talk on all the shows (Topgear, youtube) handles like a Video game: very poor feedback, very 'digital feel'. So I sent to The458shop (Ferrari 458 specialists| Ferrari 458 aero kit| Ferrari 458 EVO kit) in Bicester and installed their antiroll bar. This has made the car a lot better. Lots more feel. The next step is dampers. The guys at the 458 shop swear by the QUANTUM 2-way setup (which has a 3-way addition as well). About half the price of the OHLINS since these are a Monotone setup and not a "Twin tube" design like the TTX36s. I am thinking seriously of going with these dampers since all the hard work (setup, damper curves, etc. etc.) has already been done by the 458Shop folks over 4 years of racing a 458 Challenge car... though I've got to say nothing beats the TTX OHlins setup!!

Cheers,

-- Atul

 

Thanks for that informative post Atul. Look forward to hearing more

 

Very nice! What kind of dyno was it?

Also curious if you have experimented with different cam timing?

 

The dyno was a rolling road without corrections for pressure and temperature. Showed 444 calculated BHP at the crank but the guy said to use a 5% correction. So 420 BHP is realistic. One can feel the difference from stock quite easily.

Have not touched cam timing. It's difficult enough getting the Motec to work smoothly!!

 

Atul,

You had the intake and the heads ported?

 

Not The heads. Just the intake velocity stacks. Polishing thee gives you the most bank for the buck - about 10 RWBhP.

So the tuned Motec setup seems to give one about 55-60 BHP over Stock (assuming stock is 360, which is generous in all but euro spec challenge cars).

The extra power - especially in the Midrange - can be felt quite directly. MOTEC magic!

--

 

Correction. That should be "Velocity stacks in the airbox". The key is SMOOTH, non-turbulent airflow into the main intake chamber. It is certainly possible to get more power by polishing and modifying the intake chamber. But that would then make it difficult to return to standard later if one wished to do so. The current setup feels good - I'm trying it st Silverstone on Wednesday and Spa Sunday/Monday.

 

Your car is making a lot of power but to say the above it would need to be a back to back comparison on the same dyno.

Still I'm assuming you mean the difference in everything you've done vs stock and not just Motec over stock ecu's.

I'll have to take a look at the velocity stacks, from what I remember seeing they appeared to be very smooth as cast. Were they just smoothed out or the shape altered?

 

Atul,

What Motec are you using? Very interesting stuff indeed here...thanks for sharing bro.

 

Its the smallest MOTEC ECU, the M84. This is sufficient for the V8 of the 355.

In other news, we had some bad luck at Silverstone and SPA.

The March 22nd day at Silverstone was rained out, so good rain practice but no dry runs to check power, etc.

And at SPA on March 26/27, I only got in one practice session. After that, the power-steering pipe burst when I was reentering the F1 pits after refueling; the entry was utterly packed with several Belgians, entailing the use of full lock - a BIG MISTAKE - to turn into my pit-booth; if one holds full-lock for any length of time, especially when the car has a 'fast steering rack' like a proper racecar, then the pressure builds up tremendously. The pipe should not have burst since there's a pressure-valve to reduce the pressure but I guess that was not properly 'beta tested' .

At any rate, the next test is May 3rd at Silverstone, and then more days at DOnington Park and others. Back to SPA in July.

-- Atul

 

James - yes, what I meant was that we got about a 50-55 BHP gain from where we started. At the time of the first test, we were at about 325 RWHP, and now we're at about 370 or so RWHP, which translates to about 420 BHP at the crank.

Plenty of power but not as much driver talent . Working on that now...

 

Yesterday at Silverstone I saw a 355 CH testing and they had the stock ECU (2.7 Motronic). They had remapped the 2.7 system to bring it closer to Ferrari's claimed 375 BHP. The mechanics said they'd seen about 360 BHP at the crank, which would still make it about 50-60 BHP down on the Motec.

Another issue is weight. Because I street-legalized my car, the lights and Handbrake etc add weight. The car is now 1380 KG, while the Challenge cars in race-trim run at 1340 KG...

--

 

Yes but just to clarify, that would again be because of all of your modifications, not just the Motec.

Max power is for the most part going to be air fuel ratio and timing which is adjustable on both (though much easier on the Motec). You may find a little power with a lot of experimenting with individual cylinder tuning and injector timing but not a lot.

Still, not the only advantage of Motec for sure. Data logging, tuning on the fly and overall better/optimized driveability are all nice to have.

 

Atul,

I have a programmable computer also but not Motec. What was changed via the Motec besides timing and fuel? Where individual cylinders tuned by the Motec? I have had mine modified and it did make a big difference in throttle response and midrange power.

 

Yes of course. The final power gain is a result of all The incremental modifications. Just the Motec without any other mods would be about 25-30 HP. Airbox (optimized) about 6-7, 4x1x1 exhausts (separate banks for each side) about 7-8, polishing and smooths in the inlets from the airbox into the engine inlet tract another 8-9 BHP. So it's an incremental process.

 

Yes, agreed it's an incremental process. IMO just the motec is worth 5-10hp at best over untuned/original motronic.

 

Hi Atul, would you happen to have any photos of this work? Did you do just the stacks or the throttle bodies as well? Thanks.

 

bump

 

I think he sold his car. I saw a car just like his for sale on a website 6 or 8 months ago.

 

Ya I saw that too....wasn't sure if it was his.