Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Monty Takes A Deep Breath

Dave,

It must become a case of deminishing returns on £'s spend as you chase the extra BHP. The real acid test is the performance and enjoyment of the car on the road and it seems you have been extremely successfull.

I've always beleived that straight thru exhausts whilst they can increase high range BHP, they can reduce mid range torque. So I asked AI and it came up with this.

A straight-through exhaust will generally not improve low-end or mid-range torque on a naturally aspirated 2L Duratec engine, and it can actually cause a noticeable loss in low-speed torque and drivability.While a straight-through exhaust or "straight pipe" design decreases restriction to help peak high-RPM horsepower, naturally aspirated engines heavily rely on exhaust gas velocity and scavenging to pull exhaust gases out of the cylinder during valve overlap.

)How It Affects the 2L Duratec Powerband:Low-to-Mid RPM Torque Loss:

When you remove the catalytic converter, resonators, or mufflers and replace them with a wide, unrestricted straight pipe, the exhaust gas velocity drops significantly. The slower-moving exhaust gases fail to create the negative-pressure "scavenging pulse" needed to help empty the cylinder at low engine speeds, leading to weaker acceleration and a loss in daily driveabilty.

High-RPM Horsepower Gains:

If the vehicle is driven at a sustained high-RPM range (such as on a racetrack), the massive volume of moving gas will benefit from the reduced restriction, yielding a minor 2–5% increase in peak horsepower at the very top of the rev range.

How to Actually Improve Torque on a 2L Duratec

:If you want to maximize torque rather than just making the car louder, focus on an engineered exhaust setup:4-2-1 Exhaust Manifold: Upgrading to a quality, matched-length 4-2-1 header design (such as specialized kits from performance retailers like Retroford) merges the primary tubes in pairs to maximize mid-range scavenging pulses, which preserves and increases torque. : Avoid oversized 3-inch exhaust pipes unless the engine is turbocharged or a highly modified, high-compression build. A 2.5-inch system with straight-through mufflers strikes the optimal balance between high flow and high gas velocity. [ECU Remapping: Modifying the exhaust changes the air-to-fuel ratio and cylinder filling efficiency. Pairing hardware upgrades with a tailored ECU tune is essential to lock in performance gains.

I well remember driving one of the launch edition CX Plus Six cars on a road route with a nice testing mix of typical poor surfaces / newly resurfaced stretches & of course unpredictable potholes, at the time despite all the dealer & journo hype I was not that impressed having just driven the opposite inbound route in my (I thought at the time, well sorted Roadster) so I took the Roadster back out in the same direction as the P6, it actually confirmed that a well sorted Trad can be a very nice Mog to drive, but did need SSL, 5link etc to compete with a CX ride

Jon,

Without question there are some journeys I undertake, I enjoyed them more in my Plus 4 Sport, than my CX, they were usually very smooth surfaces, with broad sweeping bends, where the manual gave the appearance of more control. Then there are other country lanes which are more undulating, with hump back bridges, that without question the CX is a much faster and better controlled ride and doesm't bottoms out unlike the trads. On motorways or fast dual carriages without question the CV wins hands down everytime.

I was even further impressed by a new CX Plus Four, with active suspension and traction control that felt much more planted than my CX

All great points, and it's fantastic to see the debate come alive

All I'd say is, if I wanted a perfect handling Teutonic machine with a hewn from solid feel, I'd be driving a modern Porsche 911, but TBH I can't think of anything more dull.

The thrill with a traditional chassis Morgan comes directly from your exposure to the environment, and the challenge of mastering its many failings,.

Personally I like a car that has the capacity to scare the living bejesus out of me! How else do you know you're still alive, unless you play a quick game of Tag with the Grim Reaper from time to time?

Have fun, but stay safe out there chaps