Technical Exhaust Manifold Heat Shield

[s130]

Well during the 50K mile service it was clear that the exhaust manifold heat shield was shot to pieces

Three main fail point. Top shield corners above manifold. Mid section full lateral fracture in the region of the two CATs. Bottom mount corners.

For a 2005 CF3 Barchetta then the heat shield is still available (has to come from Italy) at a price of £65.

The Techical problem with replacing the shield is that the bottom bolts and top nuts will be terribly corroded and eroded.

I finally managed to remove the bottom bolts but only after Gas-Plus soaking and blow lamp heating. The top nuts failed similar treatment over 24 hours and eventually sheared.

No I have just the lower portion on the heat shield that protects the lower radiator hose. The rest just vents upwards as it always did.

This got me analysing the 2005 CF3 "B2" air intake set-up. This is a complicated three part intake system with large blind resonator cavity sections. The initial intake actually passes over the top of the maniold / heat source before getting the the 2nd and 3rd parts of the intake system. Now this is god for winter operation but for for warmer weather there is that heat induced charge density reduction.

Now resonators would not be put in (at design/manufacturing cost) unless there was some advantage/gain especially with variable intake valve timing.

Having said this I've seen many a "B" with a K&N cone filter bypassing the original intake system. Now here is an alternative view:

The original "B" air filter is MASSIVE. Far far more surface area than a cone filter and will (IMHO) breath better than a cone filter.

So one can ditch all main 2 part intake sections and just let the air filter canister directly breath. In addition the almost 90 degree bent hose (with small 30mm resonator take off) can be turned around to take air from the cooler space behind the N/S headlamp and battery space.

So I leave you with these thoughts.

I've put our "B" back as designed so have not trialled how the loss of the resonator intake system actually affects the the cars performance.

What I will suggest is that the original "B" air intake with massive air filter is most probably better than the cone filter just before the throttle body. Also the cone filter will be noisier and give a placebo effect feedback that it is better.

 

[Dave-M]

Interesting thoughts, regarding the heat shield. I replaced my shield with a new one from Fiat, probably one of the last ones on their parts shelf. But that very soon cracked and started to resonate. Did consider buying from Henk, but instead had it ceramic coated just to try to retain some of the heat. My original air intake system was cracked and not in good condition. So I fitted a K&N cone filter. This was fine but on warmer days the under bonnet heat just drained the power away from my poor B, despite the ceramic coating.
My latest set up is still the cone filter, but using an Itg maxogen filter, housed in the carbon fibre housing, to ensureI get cool air I have a feed hose from the lower front grill area.
Very pleased with this setup, I don't get any effects of the heat from under the bonnet.

 

[s130]

Well your set-up certainly seems to have a much larger air filter than the more tradition small surface area cone filter.

The original Fiat large canister filter set-up is a pretty good use of available engine compartment space. I'm not really sure I can fault it.

Where issues/comments/observations do occur is why they (Fiat) have that long intake path from the the O/S headlamp area across and above the hot exhaust manifolds and also that other large cross front blind resonator chamber.

Just air temperature/density logic would suggest taking the air feed directly from the N/S headlamp/wing forward area.

Your intake system seems to reflect what I was pondering but for both of us the original resonator tracts/chambers and their performance functions need understanding.

I'm possibly thinking that with variable intake timing (variator) the known object was to increase lower end torque and boost top end power. This was possibly a sensible driveabilty compromise. e.g. good bottom end performance, good middle and good top end. But none of these exceptional.

The torque vs BHP vs RPM has always been the combustion engines compromise. You can't have all.

 

[halfrowk]

Totally agree with your view of the huge barchetta air filter, makes me laugh when I see people binning it and fitting cone filters....getting their air from the hottest part of the engine bay!

I've gone the route of removing the resonators and fitting an air duct pipe with high flow inlet, drawing it's air from the area near the horns.
Coupled with a performance filter in the std air box I've noticed quite a difference in willingness to rev and top end performance.

Has anyone noticed the std Barchetta airbox/filter works in reverse of others of it's kind...? Drawing from the inside to the outside..... :spin:

 

[halfrowk]

Interesting thoughts, regarding the heat shield. I replaced my shield with a new one from Fiat, probably one of the last ones on their parts shelf. But that very soon cracked and started to resonate. Did consider buying from Henk, but instead had it ceramic coated just to try to retain some of the heat. My original air intake system was cracked and not in good condition. So I fitted a K&N cone filter. This was fine but on warmer days the under bonnet heat just drained the power away from my poor B, despite the ceramic coating.
My latest set up is still the cone filter, but using an Itg maxogen filter, housed in the carbon fibre housing, to ensureI get cool air I have a feed hose from the lower front grill area.
Very pleased with this setup, I don't get any effects of the heat from under the bonnet.

Dave, where did you get those plates/manifolds to relocate your idle valve..??
Who modified your inlet manifold? Are the gains from it substantial enough to justify..?

 

[Dave-M]

Dave, where did you get those plates/manifolds to relocate your idle valve..??
Who modified your inlet manifold? Are the gains from it substantial enough to justify..?

Dave Young modified the manifold you will find him on Facebook, he does alsorts of stuff regarding valve grinding porting etc. Had it done a few years ago, but only really got down to fitting it. Regarding gains I have no data as yet to say it improves performance, although it does feel more responsive higher up the reve range. Downside to the mod is the idle valve is too high in the engine compartment so you can't shut the bonnet.I did ask Dave to modify the valve to give clearance, but it wasn't enough.
The plates were my first attempt, and although they worked the bore of the inlets was too small, this gave a whistle noise and poor tick over, my latest pair of plates are 15mm internal bore and work well, no hunting on tick over and no whistle.
I had a further mod on the manifold to cut and reweld the throttle body inlet section, moving it so that the face pointed lower into the engine bay, this was necessary to fit the larger size of the idle valve plate that fitted onto the throttle body.
Plates and that second mod to the manifold were done by local a engineering firm, Dave Brooks Engines.