In 1987 the MP4/3 had used the TAG labeled Porsche V6 twin turbo that had been used by the team going as far back as 1983 in the MP4/1. The Porsche engine providing power for Constructors Championships in 1984 & 1985 whilst drivers took titles in 1984, 1985 & 1986. Williams rose to the top in 1987 using the Honda power unit which also powered the Lotus of rising star Ayrton Senna. In a move that would see the continued pairing of the Brazilian and Honda, the Japanese manufacturer moved their engine supply to McLaren where the starlet would also move for 1988.
The use of Honda's V6 80o powerplant meant that the hump in the bodywork that once resided aft of the drivers shoulders could be slimmed lowering the CoG and enhancing Murray's low line ethos. Of course the tanks design didn't stop here and seizing on the Engines lower height McLaren's design team also saw the opportunity to lower the driving position. As we can see above in a side by side comparison of the MP4/3 (left) and MP4/4 (right) the angle of the drivers backrest has been sloped more, not only allowing for the driver to sit lower in the cockpit but also allow for the fuel tank to be extended longitudinally at the base of the cockpit.
Having spoken to Tilton they have confirmed that Honda had asked Tilton to design a more compact and durable clutch for the Lotus. Tilton duly obliged providing a 5.5” diameter carbon/carbon clutch, the first to be used in F1 winning a race at the hands of Ayrton's 99T in Detroit. Tilton's clutch was a revelation not only due to the size of the unit (as most teams still struggled with 7.25” diameter clutches) but the carbon/carbon design allowed for superior heat management, low inertia, high torque capacity along with a smoother engagement. All of this leads to an extended lifespan on not only the clutch but any associated parts. The clutch also represented a performance advantage in terms of power distribution as it was able to cope with the torque demands of Honda's V6 Twin Turbo engine especially important in qualifying trim.
The suspension is an area that is probably most departed from it's modern counterparts and relies on a more inbound road car style setup with vertical strut/damper/spring combo's. The packaging in modern F1 cars still holds some similarities but with torsion bars affording a more compact way of applying control over springs they have become commonplace.
This great video featuring Chris Economaki explains the Lotus 99T/100T's 'Active Suspension':
Heres a collection of great images of the MP4/4 for you to drool over that I have found through my internet travels: