Very small diesel primaries design

[Dust Buster]

Continuing with my 91.5 CID (1.5 litres) 140 HP (104 kW) with boost set to 22.3 psi (1.536471 bar), if I may. This is two views of my OEM exhaust manifold (EM).

Exhaust_Manifold+EGR_Hole.JPG

The convention that I'd like to test with you is that with turbos, it seems to be to just get the exhaust to the turbo by the shortest route possible to get it spinning quickly helping to reduce lag and be in boost at lower rpms. The OEM cast iron design might even provide some adjacent cylinder scavenging or at least canceling some negative waves. I suspect there is very little valve overlap and that the valve, head port and EM port size are all the same. Would tapering at the turbo, from individual equal-length primaries, increase the pressure, aiding it in spooling sooner?

This is probably the last I'll be saying about exhaust systems as I have found them to be the least bang for buck, but I have done many of the quick wins already. This is my daily driver.

The only problem I've had with the OEM EM is that there's a gaping hole (#1 in both views) for the EGR plumbing. “V” clamps held the flex-tube connecting the EM to the EGR and failed to seal properly. I had the hole plugged and re-mapped to stop the idiot lights and limp mode due to the failed EGR.

What I'd like to do is remove the defunct EGR, which is just a lump of metal now. See all of the arrows in the pic. However, it has “cooling” oil lines and water pipe plumbing. Also, it is integrated with the intake manifold. That is, it would be a major job. Also, doing anything to improve the intake manifold (IM) probably won't help. It is just channeling air in from the turbo (no throttle plate on a diesel) and has plenty of oxygen, even though I decreased the air oversupply from 20% to 10% with the re-map.

All_EGR.JPG

[Kevin Johnson]

For reference:

[Dust Buster]

Well done - that's the motor, but not my exhaust. This same motor has been installed by Merc, Volvo, Nissan (40% owned by Renault), Dacia (100% owned by Renault) and Renault. Even within the Renault line-up, they position the exhaust differently.

This is my first diesel, which I purchased just before VW's diesel-gate. My life has taken a different direction from hot hatches to off-roading / green-laning. I love the torque and fuel economy, but it does stink like an old oil burner without the CAT and DPF.

[Kevin Johnson]

Do a differential analysis of why the OEMs chose to use an altered ancillary system (packaging?).

[Dust Buster]

Yes, the Clio's is closer to the firewall than mine requiring another 90 degree turn. Some of the others are similar. None allow one to dangle their feet into the engine bay though.