And if the Sprintex was dead....?
I had a heavy program since beginning of September, both on the working side and on the Sumo side. Here is the summary of what happened:
Beginning of september, I was back on the mapping process, and this time, I had a separate approach between the engine atmo requirements and the extra fuel required for the supercharger boost. That was giving me a better "unmixed" result, and it will prove to be the right approach.
Some road testing with the usual limitations due to safety and license points, and I was ready for the track session on 5 of September with the local oldies club from Reims. A nice warm dry day, where Clairlady (my daughter) had a lot of fun drive with the Roadster 2000, showing some who did not knew her what she was capable of doing. My side with the Sumo was not as good, as even with cleaning and drying the connections on the supercharger tubing under pressure, I drove about 15 minutes (to get the right feeling about the improvements!)... and the pressure was off again. I spent the day putting back the tubing, getting the conviction that this time, something serious had to be done about it!
Back home, I had two week-ends to solve the matter, and i decided to take all tubings out, and have welded rings made on each tubing end. Then the collars had a stop for the slip, and this was good for the tubing that could be welded. The 4 remaining pressure connections were:
Sprintex outlet, intercooler inlet, intercooler outlet, and throttle inlet.
Aluminium tubing on all parts, so not possible to make easy rings by welding. I decided to implement springs or hooks that would physically hold the tubings in place. I could not find springs, so I placed hooks with the right tension on each of them, and this time, I was really safe on that pressure problem.
Second track day on 27 of September, this time with the Road Runner Club having modern and old cars, and quite a number of members from the Renault techno center where Sylv1 is working (thanks to him for the proposal!). That day was absolutely awfull! We drove in the morning, lowering speed on the motorway, as driving 60 miles an hour was like in a swimmingpool! Very instructive driving, of course, as now I had the power, but the pouring rain was making the experience as driving on ice... Spins? I do not remember, but many for all of us!! I then realized that my tires being ...mmm? 10/12 years old, what was correct on the dry was just hopeless on the wet (with rivers of rain through the tarmac!!) So, back home safe, but without any possibility to push whatsoever: the car was sliding sideways on third gear acceleration on the staright part of the track!
Third trackday was planned for 13 of October in Magny Cours, so the car was ready, and there was not much to do... but just hope that the rain would not kill the day as it did on the last session...
Start on the Friday for 400 km, with Clairlady pulling the trailer and the Roadster 2000, and me driving the Sumo... 200 km with half under the rain, but I had new R888 tires fitted, so the feeling was better. Due to the wet tarmac and the new tires, I did not drove faster than 100 km/h, so a slow 70 miles/h...
Suddenly, I had a vibration as when you roll over those thick rough paint marks on the road, and that was lasting only a few seconds, then back to normal. Another 15 km, and then some metal parts were loose under the bonnet, fell on the road bumping under the car body... and silence... ?? I suddenly realized that the typical Sprintex noise was gone, and looking at the pressure gage, accelerating of not, the pressure was staying 0 or negative under vacuum when throttle was closed! I could not stop safely along the motorway, so we stopped at the petrol sation that was some three kilometer further.
The good news is that the mapping basically switched to atmo management without extra pressure, and the car was running fine... only with the push lost when opening the throttle. The bad news is that by opening the boot, there was no belt nor pulley on the Sprintex shaft! GONE!!
No spare pulley, and no assembly parts: I could not use the sapre belt! We had a coffee to discus the situation: Back home was two hours, but no parts ready there either, and four more hours to reach Magny Cours with anoter car... or just continue and have the session as atmo 280ZX? We choose the second option, and I installed the management PC with the Emerald software running showing and recording the Lambda value to keep safe (First experience to run the car atmo). The map was OK, and I did not required any adjustment for the rest of the drive, the track session, and the drive back home.
The shaft of the Sprintex is siezed (or the inside screws are blocked, or the gears/roll bearings are seriously damaged). The plan is to disassemble this coming week-end to have a look inside and check the situation. The sprintex oil was down when the Sprintex stopped, and the Sprintex temperature was high. Driving in the rain was no trouble until now, and the outside temperature was much lower than on June/July and september drives. I have no real history about this Sprintex S-102, aprt from being 30 years old, and previously used on two cars for carb pressure feeding. I drove some 7500 miles since the restart of the Sumo, and this should not be significant for the sprintex life... but it all depends on the consequences having stayed 10 (?) years without running.
I will open it and se what I can see... Sprintex Australia is giving me no answer to my questions about spares (Mark Ambrosius who gave me the data for the oil tank, level, and oil type to be used is silent). I suppose that asking spares for a 1980 model will be hopeless...
The originality of the car was the supercharger approach. I was having no problem with the engine and the mapping with my slow and secure approach. The Sprintex is supposely dead, and I am left with some options: Forget about the car, turn it back to turbo (but this means a lot of changes), or spend another...?? to have a new supercharger fitted. I will need some time to decide, but winter is coming and leaves some time to decide. I do not imagine to find another (good condition) S-102 model, as those are rare units... probably deeply sleeping under rusting boots...
The reality is sad, specially when I do not understand what could be wrong apart from the Sprintex itself, and even after a year of test drive and management approach...If the engine had blown, I would know that I was wrong on the mapping, but there...??
Sorry to give you those news, but you and I knew that it was not the easy project, and failures can occur. Should I swap the engine for a SL55 AMG with supercharger...?
