1997 V8 Lotus Esprit Rebuild (and improvements? 🤷‍♂️)

[Thartje]

So if you read the first post I mentioned this is more of a look back on a build that was already pretty far under way. So as of current the Esprit is actually running now but not fully drivable. Still going through the process of being tuned on the dyno. Video below is just a short clip of it idling. I will keep updating this thread as I have time with the progress and changes I made through the build. May be able to share some lessons and regrets now that its running also 😂

 

Once I had a solid plan for the shifter I needed to start working on running new oil lines though the tunnel. Would be a lot easier to accomplish this with the shifter out of the way. I decided to move everything over the AN lines for the oil hoses. They are slightly smaller OD but near identical ID for the oil flow. Also, in Arizona and even if the car is garage kept rubber never seems to last as long. With some searching I was able to track down some adapters for the oil coolers from BSP to AN, I believe through Racetronix or Pegasus. I finally had the oil coolers mounter too at this point and had no issues with the extra fan shrouds and fans fitting. Plan was to have these controlled by the ECU based on oil temps at the ending, so didn't take any time to add temp sensors into the fittings/coolers themselves.

 

    

 

I was also focusing on intake temps still at this part of the build not just oil temps. The Intercooler / chargecooler setup was done really well and quite compact but that also brought in the issue of cold side parts being close to the hot side part. (really this is a huge issue in the Esprit v8 even in the original design) I do believe the cerakote will help here but really not the end all of extreme heat management. I did pick up some DI fiberglass & gold protective sleeves to add a barrier to the charge pipe, also started looking into turbo blankets at this point too as they seemed to be an option to really cut down the heat soak from the turbos. As you can see from the compressor outlet below the compressed air passes right under the turbine housing.

  

 

[Thartje]

Had the intercoolers and heat exchange setup but didn't have anything setup for a water reservoir or a pump. Although I never tried it, I figured the spare tire was no longer of any use to me as I had larger front brake calipers. Also, the rear wheel wouldn't fit in the trunk at all if I had a flat in the back... so I decided to sacrifice the spare wheel space for the reservoir 😂😂 (This provided a further good decision as I changed the bolt pattern and the spare wont work anyways)

Decided to use amazon boxes as a unit of measurement to avoid having to use the metric system. It seemed to give pretty much max capacity and still keeping the hood from opening/closing without the hinge contacting. Water volume was was important aspect of the intercooling setup but also needed water flow. As I was moving to a stand alone ECU I figured I could easily setup a PWM pump for maximum flow. Decided to pickup a Pierburg water pump which I immediately painted to look like a Duracell battery 🤦‍♂️😂 (The color scheme looked cooler in my mind) This thing would require some heavy duty wiring and a 40 amp relay, certainly had to flow to keep the water moving.

  

 

 

In the same week of making this poor pain scheme choice I decided to paint my wastegate solenoid... which also came out looking like a 9v Duracell 🤦‍♂️😂 At least they are relatively well hidden from view.

 

Although I had what felt like a lot of odd jobs to do on the Esprit after the engine was together I still had one major one to tackle with the Renault UN1 transaxle.  I had rebuilt an engine before but this was going to be new territory for me. Fortunately there is a very detailed YouTube video series from someone rebuilding a UN1 for a DeLorean. The head mounted camera view and what feels like over accentuated body movement make it so you can only watch it in about 45 second spurts, but its extremely detailed on going through a UN1 rebuild.

I went with the GTO Engineering kit for mine. They seemed to be pretty well tested and were in some of the GT40 replica cars using Ford V8s. Lesson learned, if I ever did this again I would go with the Ford spline option on the rebuild kit and open up a wider range of clutch options. Really limited to AP, Helix or Clutchmaster for a ground up clutch option with the original Renault splines.

Other than being a single piece input shaft the GTO upgrade also has a much more robust 5th gear. Sadly, still not supported on the back but hopefully sufficient to hold more power. It is certainly a lot thicker and does not have the deep channel after the 5th gear splines. First gear is also straight cut for strength and should give an impressive whine. 😁

 

 

Rebuild process was honestly very easy, but I did take a lot of pictures coming apart so I knew how they went back together. I picked up some decent heavy duty snap ring plyers and a gear puller from Harbor Freight to make the job easier. Was really able to knock this out in an afternoon, not too bad of a job.

 

I also picked up a Quaife limited slip differential, figured I might as well do it right if I was pulling it all apart. I had installed a similar worm gear/spur gear unit in another high horsepower car and it really did make a difference. I didn't get much seat time in the Esprit before it shit the bed but looking forward to seeing how this thing does  😬

 

 

 

[andyblackman777]

Really enjoying your posts. 
I recently installed this and the quaife diff. My only issue was the snap ring/circlip that goes on the end of the shaft (clutch end ). As the shaft is thicker the original won’t fit and I could not find one of the correct size anywhere. Thickness was the issue. 
I ended up re using the old one after making it larger, not ideal. 
Very happy with the result though. 
Andy. 

[Thartje]

15 hours ago, andyblackman777 said:

Really enjoying your posts. 
I recently installed this and the quaife diff. My only issue was the snap ring/circlip that goes on the end of the shaft (clutch end ). As the shaft is thicker the original won’t fit and I could not find one of the correct size anywhere. Thickness was the issue. 
I ended up re using the old one after making it larger, not ideal. 
Very happy with the result though. 
Andy. 

Thanks man! Hope they are helpful, wish I had started this at this start of the project.

 

I don't remember replacing any of the snap rings so I probably reused mine also. Nothings come apart yet, so I think we are good 😂

[Thartje]

I was working on this transaxle rebuild at the end of 2022 but had to take a break as my wife bought me an really awesome Blaupunkt Bremen head unit for Christmas. Doing a radio install seemed much more fun than a transmission rebuild and I wanted to see how the modern retro looking unit went along with the Esprit's interior 😁 Going into the junk pile was an Alpine unit that I don't believe was original to the car. It wasn't really a bad head unit but just didn't fit the look of the interior. I actually pulled the face plate off and never got a chance to use it because it would never turn off, I figured it had been wired wrong.

 

 

 

Sooo I got my nice new Blaupunkt Bremen installed and... it wouldn't turn off either. As you can see, key out of the ignition and the head unit still fully awake. Despite that issue I was really happy with the way it looked in the car. Very 90's but still had bluetooth for phone/streaming, will read SD cards for MP3s and the backlights can be adjusted through the whole RGB range.

I started into the staying on issue by double and triple checked the wiring and found I had it correct. Eventually found there was an "key in" relay that was stuck on, but only because it was getting energized.

 

Traced the issue back to the ignition key cylinder and found this... The spring that returns the cylinder back to the "key out" position was broken! Not sure if this is a common issue but was easily overlooked. I had assumed the previous owner wired the radio incorrectly 🤷‍♂️😂

 

  

 

Was a simple fix in the end, was able to track down a replacement ignition cylinder. I was thought about replacing just the spring but the spring perch had actually been worn down. Was able to pick up the whole piece from Amazon for $15 with two keys. Its actually a ignition cylinder from a Vauxhall Astra and some other random GM cars. So if your radio doesn't turn off and/or your Esprit has a battery drain issue this could be worth a check.

 

 

[Thartje]

Radio was sorted out so back to the transmission! Had previously assembled the new single piece input shaft and moved everything across that was necessary. I did find some ARP bolts for the ring gear to go back onto the Quaife differential (I think through JAE). Getting the shafts back into the transmission case was pretty easy but I did have to take a few stabs at getting the top part on. Not sure if it weas something I was missing/not seeing but eventually tracked it down to the blue seal on the input shaft being a pretty tight fit. Went together in the end and was onto the side adjusters and preload setting.

 

 

Side adjust on the UN1 is similar to an Holden Monaro / Pontiac GTO which is about the only other differential I have messed with 😂 The differential side adjuster on the 05 Pontiac GTO required a special and expensive tool which can be substituted with a $9 oil filter wrench. So busted out my trusty AutoZone universal wrench and made some minor modifications to it as the teeth on the Renault UN1 side adjuster are a little smaller. I did end up having the universal tool welder as the UN1 requires a considerable amount of torque to turn... so will have to spend another $9 if I need one for my GTO in the future 😂 Either way, this is a pretty cheap solution for a UN1 adjuster.

 

  

 

Once tight I started to dial it in with the preload procedures. Not sure if there is a specific tool for this job either but made use of a fish scale I had picked up years ago from Cabela's. This did take a few attempts to dial in but was a pretty simple process overall. Just a case of wrapping string around the diff and seeing how much force it take to rotate it. I didn't come across any other checks for adjustment in the service notes but checked the contact patch with gear marking compound and had good contact. Not sure if that is an assumed step by the service notes or not required if the preload is accurate? 🤷‍♂️

 

 

 

Next thing to deal with that would prevent me from mating the transmission to the engine was a clutch that would hold with torque from these improvements. I contacted Falcon Clutch in NY and had a good conversation over the phone. I had talked to several clutch builders but honestly Falcon was the first builder that gave me confidence that they understood what they were doing. Asked them to rebuild it to handle mid to high 500 torque range. They explained how they could do that and any potential impacts to feel/drivability. So, packaged up my clutch and sent it across country to NY. They did amazing work and in the end the clutch performed way beyond expectations and the 500ft tq range 😂

 

[Thartje]

Clutch was away so had some time before the engine and transmission would be going in. This was probably around the time I decided the whole interior needed to be replaced. The previous owner had replaced the carpet and the headliner. The carpet quality wasn't bad but the installation job wand fit was pretty bad. The previous owner wasn't aware that the there were carpet kits available for the car and sort of threw something together with really tacky vinyl strips around the seatbelt openings and parking brake, not the robust leather the car originally had at these points. 

The headliner was a worse issue. it appeared to be spandex material that had been installed with a hot glue gun. I later found out it was the same glue what had been used to install all of the carpet.... Removing this took days, but that was a problem I wouldn't find until later  😂 The headliner was also made up of little scrap pieces to cover up where the material wasn't either measured or installed correctly... it just all had to go.

 

   

 

Once I pulled the interior trim pieces out i also found sections that had been "repaired" at some point but not very smoothly. Another item to address..... This was all stuff to take care of in the future but had to start planning. So started looking into material options for the headliner, my heart was pretty set on Alcantara as it just has a cool look to it... more suitable for a 90s supercar than spandex. Also hopped on the carpet waiting list with Steve M 😁😁😂

 

While I was trying to decide on interior options my buddy was working away on building my intercooler reservoir tank to go up front. I wanted a front tank for maximum capacity to reduce heat soak and also to keep it away from the hot engine. As long as the water could be kept cool it should be effective on reducing the IATs. Jeffrey came through with a really well aluminum tank that had a bracket for the pump also. I decided quickly that it needed to be powder coated black as it just looked a little too shiny and out of place..... 

 

 

I did have to drill a couple of holes in the fiberglass for bulkhead fittings as coolant needed to come from the radiator back into the reservoir and also out again to the intercoolers themselves. One hole is rather unseen at the front however the hose to the intercoolers was a little more difficult to keep out of sight.

 

It was around this time i notice how ugly the black frame over the ABS was looking.... so powder coated that too

 

Then I noticed the cover for the air plenum for the AC inlet was pretty ugly too, so I decided to remove that and Cerakote it flat black....

 

I then realized how ugly the two black bolts and washers were that I believe hold the wiper arm in place were looking... so those too got powder coated black

And then of course while I was adding wiring and relays for the water pump I realized how ugly the arm holding the relays was looking, so that also was removed and powder coated black, despite it being under a plastic cover most of the time... 🤷‍♂️🤦‍♂️😂

 

But by the time I had gone through all that process the good news was my Alcantara sample had arrived 😁Along with my new boost gauge from Caerbont. Designed to look like the original gauge they made for the Esprit V8 but with a new max boost to meet the target I was going for. 

 

 

 

 

 

 

[Thartje]

Some more photos of engine progress before it was installed. I moved over to ball bearing turbos so needed to make new oil supply lines. Journal bearings cant be over oiled (assuming the drain is adequate) but ball bearings need a lot less oil. the 3an line and oil restrictors were pretty simple to make but tracking down a decent looking banjo to 3an actually took some time. I finally found some that were made for brake calipers but worked just fine for oil also.

Also wanted to add heat blankets to the turbine housings before the engine went in also. These things aren't impossible to install on the car but a lot easier when the engine is out with low mounted turbos. Could have snatched up some amazon brand heat blankets but decided to go through Funk, figured British car - should support a British company. I was pretty impressed with the quality of these though. I do use the cheap Amazon brand on my LS TT car and these Funk blankets are really more robust.

The turbo blankets do a lot to improve heat soak into the engine bay and keep the turbine housing warmer, which results in faster spooling. Not sure how much of an improvement the  turbo spool up is, but the heat mitigation is worth it alone.

 

 

Couple other items I picked up for the build were a turbowerx exa pump and a high torque starter. I never enjoyed hearing the starter ring on the fly wheel when the car started, I'm pretty sure they were not the greatest units from the start. The fact that I had bumped compression and tightened the piston/wall clearance meant I was putting even more load on this original unit. The new started was pretty much the same dimensions as the original, minus the extra bump on the back for a shaft.

Other item I picked up was a turbowerx exa scavenger pump. The oil drain setup on the stock Esprit is not ideal. On the track one long sweeping corner could prevent adequate draining, or sitting in traffic if the car isn't level could result in the same situation. Usually results in a smokey turbo and a wild goose chase trying to find a non existent issue. These little pumps have great suction and will continually move oil, much better for oil drain than the 90 degree into the pan. I still had not figured out where I was going to put it at this point, but it was so small and compact the options were pretty open. I'm pretty sure you can mount these 5ft above the car and they will still pull oil 😂

 

  

 

 

So the engine was pretty much ready to go at this point. Any work left to do I could access from the top or needed the engine actually in the car to address. So had some engine hoist brackets fabricated and promptly power coated them gold... wanted it to look classy as it was getting dropped in 😂

 

 

 

Just around the time the engine was going in I also received a special order ESPRIT transform decal for the car, in gold of course 😂

 

 

 

 

[jonwat]

14 hours ago, Thartje said:

keep the turbine housing warmer

I understood heat needs to dissipate from the turbo in order to stop the residual oil in it from baking to carbon deposits when the engine stops?

[drdoom]

Both points are correct.

The natural rate of dissipation would not be ideal in terms of the bearing oil, which prompts measures like timed pumps for circulation after shutdown. In earlier times manufacturers fitted coolant passages into the bearing housing in an effort to reduce coking of oil in that area.

Cheers

[Thartje]

17 hours ago, jonwat said:

I understood heat needs to dissipate from the turbo in order to stop the residual oil in it from baking to carbon deposits when the engine stops?

The v8 has a recirculation pump for the cooling system. If the car is shut down when hot it runs the radiator fans and pushes the coolant for a while so it should keep the heat out of the CHRA.

I do also have the inside of the turbine housing ceramic coated so less heat is making it into the turbine housing itself to begin with.