MrDangerUS

FYI: Comparing to OE, Derek Bell and Holloway/EMCO decreased first gear ratio focusing on addressing synchronization engagement issue. It did not drop the first gear ratio as extremely as Quaife/GTO kit. Gear OEM Derek EMCO GTO Bell ratio 1-st 3.364 3.0 3.0 (GTO 2.66) 2-nd 2.06 1.933 1.933 (GTO 1.75)

Here are the distributors used on Esprits: USA 86’MY onward HCI (1987’Servc. Notes)……88 USA Turbo Bosch……… ……88 ROW/UK with carbs 45DM4 # 426XXX? has: ................................45DM4 # 42675A……………………….45DM4 PN#42653A, Vac capsule No:________………….……..Vac capsule: 16 14P 54405132……Vac. c 16 14P 54405132 28° vacuum....………………………………………………..28° vacuum……………………..……………..28° vacuum 15° static.……………………………………………………..15° static………………………….....……………9° static 15°hot idle...…………………………………………………..15° hot idle………………….….….....…………9° hot idle centrifugal:0-1000: nil………………………centrifugal:0-1000rpm: nil…………..…………….centrifugal:0-1000: nil, …………2500rpm -3°……………………………………..2000 +3°……………………………………………2000rpm +11° …………5000rpm -6°……………………………………..5000 nil……………………… ………........5000rpm +8° The early turbo cars (’86 & ’87) distributor has no centrifugal 'advance'. To the contrary, it provides up to -6° centrifugal retard. All 'advance' comes from the double sided vacuum diaphragm on the distributor, and varies from advance to retard relative to the vacuum or boost present at the two hose ports. One side is plumbed direct to the vacuum port out close to the plenum. The other side goes to that 3-nipple TIV valve, which switches between engine-driven vacuum pump on cold start up (max vacuum = max ign advance = fast idle... along with the throttle jack diaphragm fast idle), and the throttle edge port vacuum spigot. At the full throttle/ full boost, the two sides of the distributor's vacuum diaphragm will see similar pressure, and there will be little or no vacuum advance/ retard. The engine will see the 15° BTDC static ignition timing, and that will be progressively reduced by the 6°of mechanical retard as the rpm increases. Ignition retard with increasing boost/rpm keeps the engine from melting down. Beyond that, the ignition timing control is conservatively set up for an emissions engine, and is more biased toward running clean than making power. PN#42653A this is the distributor you want. It's the same distributor as I used, Lotus just timed them with 1 more degree BTDC at idle in '86 & '87.

Before, it looked like any other Esprit rear end.

When I bought my '88, my first impression was that the rear end looked disorganized. Layered horizontal body lines clashing with multiple color vertical swatches of the Toyota tail lights and a "black hole" plinth in the middle looked odd to me. If it were a black car, this graphic scheme wouldn't look so incongruous. To adjust the "incidental" styling, I replaced tail light panels and stream lined the rear end horizontally. In my opinion, this arrangement looks much better on the red car. Even on the black car it looks much "cleaner" !

Mark, FYI, Stevens exhaust and the G exhaust are not similar, regardless of it's being a UK, ROW or Federal car. There were some clearance problems on US cars, start from page 33 here https://www.lotustalk.com/threads/penelope-pitstop-resurrection.335777/page-33

Bernard, Remember, eBay is your friend! Buy these: Relais 5 broches 12Volts 80A / 60A neuf - 12V : https://www.ebay.fr/itm/114259033166?hash=item1a9a5e7c4e:g:cOMAAOSwKIdaUvhA&amdata=enc%3AAQAHAAABAEx8s0vJv0%2Be8Be2AnbIGtvBeXE%2FpNPirIlpb8OMduTz4Jf9LJQBQ0wmYWT96gX84gpXaeYfDmJRkgCFtpqPgXwundirEirudeIVOIs1HDsnzQReov%2FDTKKlN02ZQSG47QCLMcQ6zEpiRoybgX%2FHCAUaB2q4z9IzVVroL1WdRjCFJ1Bcd31KcPO8yO9OZLCTOsRpQfddMJ6DndezEb9%2FGf0mQ8LbEtUzQcNDdjQZ6rG6cg0l6%2B0ssT4dCrcfTmYsVoL11DbQGnvlA6vOXCkIbnI3z68yXc0V3XcpfOi9ahSDLf%2FjDEnGQ1Jp051V8Xx%2Flv5%2BzBMgHzUseS8BhHxJ5Os%3D|tkp%3ABk9SR9aoidjmYQ

Of course. Meanwhile enjoy some numbers from my file: ............ ......... .. Kent Lotus HC OE Turbo D.Smith QED QED QED QED MITS9 MITS9 Lotus HC INT. Cam ID ..... L14 104/107 107/107 DS2 Q420 Q420 Q420 Q420 BP255 BP270 104/107 104/107 Cam#valve/type 4/DHOC 4/DHOC 4/DHOC 4/DHOC 4/DHOC 4/DOHC 4/DOHC 4/DOHC 2/SHOC 2/SHOC 4/DOHC 4/DOHC Int. Total Lift .415" .410" .378" .415" .420” .420 .420 .420 .425” .433” .410” .410” In. Opens, BTDC 35° 32° 22° 36° 38.5° 40.5 38.5 36 28° 24° 30 30 In. Closes, ABDC 67° 60° 50° 64° 66.5° 64.5 66.5 64 64° 60° 62 62 In. MOP ATDC 106° 104° 104° 104° 104° 102 104 104 108° 108° 106 106 Int. Duration 282° 272° 252° 280° 285 285 285 285 272° 264° 272 272 107 cam Exhaust EX. Total Lift .378 .378 .378 .378 .378 .378 .378 378 .378 .378 .378 .378 EX. Opens, BBDC 50 50 50 50 50 50 52 56 50 50 54 56 Ex. Closes, ATDC 22 22 22 22 22 22 20 16 22 22 18 16 Ex. MOP BTDC 104 104 104 104 104 104 106 110 104 104 108 110 Ex. Duration 252 252 252 252 252 252 252 252 252 252 252 252 Overlap 57 54 44 58 60.5 62.5 58.5 54.5 50 46 48 46 LSA 105 104 104 104 104 103 105 107 106 106 107 108 Cam advance 0 +1 +1 +3 +1 +2

Wow, new grinds? I'm all ears! What are their specs?

In my opinion, the "104" cam and larger intake valves should help quite a bit. Two "107" cams can give you max. 44° overlap with 104/104 MOP pulleys. But, 104/107 cam combo with 104/110MOP pulleys will deliver a more favorable 48° overlap. Garry Kemp offers an optimized intake valve, which measures 36.75mm and fits onto the standard valve seat insert (the seat needs re-cutting to accept the extra 1.25mm diameter). These valves are an improvement over the original S300 valve, which had not a particularly good head shape. Garry's valves are 0.25mm larger than a S300 but more importantly, the valve head shape was developed on the flow bench and flows better than the factory S300 valve! It is one piece stainless steel with a waisted stem. Also, they are cheaper than an S300 valve. In addition, one may increase the final drive ratio to move the engine work point up the torque curve. Also, this thread has some meat:

I'm investigating a feasibility of the similar modification for my friend who has 1978 2.0l car. I'll post my findings, promise. Meanwhile, I found something interesting... I did not know that S300 valves may fit 907 (912?) head... I think Gorgio's is 912 Giorgio said (see below) that he was able to use S300 valves without changing seats, just a machining job. That's very exciting! It means a significant improvement in engine breathing ! What is your opinion? ***** I found this statement in Gorgio's thread https://www.thelotusforums.com/forums/topic/53461-rebuilding-upgrading-an-912-engine/?page=2 Basic Account 1.8k Name: Giorgio Taricco Car: Lotus Esprit S2.2 1981 RHD from UK Location: Torino Joined April 5, 2007 Author REBUILDING & UPGRADING AN 912 ENGINE Posted November 24, 2020 I have fitted 300S valves, the biggest one you can put without changing the seats, just machining job with the correct angle, I have bought the In&Ex valves from Garry Kemp.

To All, Would anyone specify for me the differences between 907 and 912 engine heads, valve dia, etc? Giorgio said (see previous page) that he was able to use S300 valves without changing seats, just machining job. That's very exciting! It means a significant improvement in engine breathing ! Please educate me. Thanks. John

Hi Jacques, (never say that when flying a commercial Airline! LOL.) Could you write a couple words about your CF rear hatch project and associated weight savings? Thanks

NEW DESIGN CWP for CITROEN GEAR BOXES Comparing to the original Citroën CWP, the new US “reverse-cut” design version addresses several critical deficiencies in the old OE parts. It offers following improvements: - reversed direction of the spiral - correcting the OE application flaw (now, force is applied to the correct flank of the tooth) - larger pitch resulting in increased tooth thickness (30% strength increase) - robust pinion tooth design, (quantity revised from 8 to 7, thicker by 2mm) - robust crown gear teeth, (quantity reduced from 35 to 31, thicker by 3mm ) - tooth pressure angle revised from 14.5 deg to 20 deg, (directs the load downward toward the thicker part of the root) - 1:4.428 ratio is more favorable for an improved acceleration. More fun to drive your car ! - Aerospace grade alloy steel 18CrNiMo7-6 w/deep heat treatment (as critical aircraft engine parts) - Optional Cryogenic Deep Freeze Tempering (available upon request) For more details PM me at MrDangerUS@hotmail.com

Rod, Issue of spacers and boost control was explained/discussed in postings #111-114 here: https://www.lotustalk.com/threads/1986-88-bosch-cis-k-jetronic-injected-esprit-specific-items.101095/page-6 To prevent thermal damage to the diaphragm I fabricated 2 gaskets and an insulating spacer/disc using "Graphoil" graphite substrate bought on eBay. There are two of them, one on the "hot" side (0.030" thick), and a second one (0.010") at the bottom. Disc is 0.030" thick. These aluminium spacer rings were added to re-calibrate the boost level at which the w/g opens. Proper length of the spring should be 105-110mm. Normally, it happens at 7-7.5 psig with the ring, and at 9-9.5 psig without it. Majority of 83-87 (and some 88') Turbos had their boost restricted to 7.5psig by the means of installing an aluminum spacer ring between two halves of the waste gate. Reason: There was an issue in the early turbo cars, which had to do with cast pistons crowning and causing excessive piston top clearances, which in turn caused hot blow-by contributing to the ring land failure, consecutively resulting in broken rings/ pistons. HCI and later cars received forged Mahle pistons, which solved the problem. NOTE: If you did not replace cast iron pistons with "later" forged ones, DO NOT raise the boost over 0.65 Bar. ..

Esprit exhaust flow improvements The largest obstacles to Esprit exhaust performance improvement are: 1. boost restriction limited to 7psi (despite advertised 9.5 psi), 2. OE turbocharger turbine exducer port diameter (1.90") is too small for good flow. Replacement turbo turbine should have ~2" exducer to reduce exhaust gases back-pressure /choking. 3. Turbo-to-down pipe adapter, (also acting as an external w/gate gas mixing chamber), is waaay too restrictive. As I said before, the adapter/extension on the 1984 - 1988 turbos cannot be opened up, because the wall of inner passage tube is too thin. I.D. of the tube measures 1.9" and the wall thickness is only 2.7 mm. If larger /improved turbocharger installation is intended, the OE adapter has to be redesigned! OEM 84-88 Turbochargers have a restrictive 48mm turbine port (Yikes!). New turbine cover with a larger port should be found and a new larger wheel fitted. Reduction in back pressure is amazing. With this mod, the recirculation BOV installation is highly recommended to prevent turbo surges. If anyone thinks about modifying this area on your Turbo car (late G-body as well as Stevens USA/Australian Esprits equipped with K-Jetronic injection), please be informed, that I am in the process of quoting of the custom adapter with a larger throat. See pics of the prototype, below. Inner pipe measures = 57/8 mm dia I.D. 5 bolt flange will be replaced by "stock" 4 bolt style flange, like in the last picture. Please let me know if you want one like that for your car. At the moment, I can't give you a definite price, but it will drop when more parts are ordered. .

FYI, here is a quite interesting paper: https://www.semanticscholar.org/paper/Inlet-Swirl-on-Turbocharger-Compressor-Performance-Huang-Liu/cd3dc3022964c1ffe104f62f252c4246ecc05708 and https://www.semanticscholar.org/paper/Effect-of-Prewhirl-on-the-Performance-of-Najjar-Akeel/c4434b77acbc869bf7f9afd0d12ab67f312b5f6a

Correction: In a few postings prior to Sept 2019, there is a typographic error regarding CWP ratio. CORRECT Ratio was always intended to read 1: 4,428 (31 teeth on crown gear and 7 teeth on the pinion). Comparing to OE, a slightly higher ratio improves the acceleration, thus making car more enjoyable. One can go drag racing, now. Just saying... Check on your own, here is a great gear calculator with traction graphs: http://www.gtsparkplugs.com/GearCalc.html Cheers John

Marrs Automotive in in Santa Clarita, California can do it, including the R&R if necessary. Jean Francois specializes in Citroen. He basically took over after Jerry Hathaway died. https://www.marrsautomotive.com/

Hey, Giorgio, I read this thread again and I want to complement you on your effort and documentation. How is your gear box working (now)? Are you still driving your Esprit or sold it? Ciao

Jacques, LSD is hibernating on the shelf waiting future lump pull-out.

Congratulations Mike! Any pictures?

I also had a low pressure reading at the tick over on my S4S (32K miles). When hot, it was in the red zone. Front glass (plastic) on 3 original Caerbont gauges separated /caved in. PO tried to repair by gluing them, but they failed again. Use of cyanoacrylate fogged my water gauge. Got p.. off and have replaced all with metal can VDO gauges and senders w/real glass. Original parts were made of plastic and failed miserably. In addition, my new turbocharger does not require full oil flow. Triple ball bearings CHRA has an oil restrictor (0.4mm hole) raising oil pressure in the whole system v. effectively. Tick over pressure never been below 20psi hot.

To avoid "dry starts", some manufacturers add engine pre-lube pumps. Adding such system on our cars would save bearings. Interesting start-up sequence in this video.

I have learned about Lucas Oil Treatment "honey" in the 80-s. Fantastic product, it sticks and coats parts even if you leave the car sitting for a long time. Esprit S4/ S4s has an interesting feature: with engine not running, when you depress accelerator pedal to the floor you can crank the engine as long as you want without starting it. In this pedal position, the ignition and injectors are disabled. This feature is advertised as a method to "clear" your flooded engine.

@Sam Grant No need to re-map, unless you're tracking the car.Turbo delivers stunning performance with OE S4s MK V chip and 370 cc/mm RC Engineering "peak and hold" primary injectors and 270 cc/min (25.7 lb/hr) RC Racing high impedance secondary injectors, (the same as Dermot's, https://users.ox.ac.uk/~ohare/ ). please gimme a shout at mrdangerUS@hotmail.com for further details