Z320 Posted March 5, 2023 Report Share Posted March 5, 2023 (edited) Hi there, on the photo below you see a TR4 with a Moss Supercharger, for sale at Switzerland. Does anyone know what the red marked box is for, please? At the Retro Clasics fair at Stuttgart there was a MG TD with a Moss Supercharger without this box, an aluminum "thing" was bolted on there. Sadly the owner knew only how to fix the set, nothing more. The Mercedes Benz 230 SLK Superchargers (my car new from 1998-2005) don't have this box. Thanks in advance. Marco Edited March 5, 2023 by Z320 German word in the text Quote Link to post Share on other sites
FatJon Posted March 5, 2023 Report Share Posted March 5, 2023 Marco it’s a bypass valve. It connects the inlet and outlet of the charger together under high manifold vacuum when their is no need for boost, for example on overrun or light cruise. It improves efficiency as the supercharger is unloaded when no boost is needed. Some have it, some don’t. Quote Link to post Share on other sites
Z320 Posted March 5, 2023 Author Report Share Posted March 5, 2023 (edited) Hi Jon, thank you for that information. On the R170 230 SLK there is not "such" a valve direct on the supercharger but an external bypass (valve) on the air filter box and a magnetic clutch for the pulley. On My R170 the ralais for the magnetic clutch failed (poor soldered on one of the relais), this is why the car run with about only 100 HP instead of 200 hp until I found the problem. The difference was very impressive! Ciao, Marco Edited March 5, 2023 by Z320 Quote Link to post Share on other sites
Z320 Posted March 5, 2023 Author Report Share Posted March 5, 2023 (edited) Got it! It is a vacuum driven item, like the advance unit on the distributor, connected with a "pull rod" to a lever on a shaft. The shaft goes through the supercharger and opens a trottle inside the supercharger! This is a photo found at eBay from a M112 supercharger for a Jaguar. Good to know now, thank you. Marco Edited March 6, 2023 by Z320 Quote Link to post Share on other sites
Tim D. Posted March 6, 2023 Report Share Posted March 6, 2023 Yep that's it. I have the moss supercharger setup and the good points of the bypass are increased efficiency at cruise (I get more than 30 mpg) and lower wear on the supercharger. Bad points are a very slight hesitation (particularly noticeable when cold) at low revs. I have added some valving so I can prevent the bypass operating when I want. Makes quite a big difference in low end torque on snap throttle opening. Quite a simple thing to do with some tubes and a pneumatic valve. Tim Quote Link to post Share on other sites
Z320 Posted March 7, 2023 Author Report Share Posted March 7, 2023 Hi Tim, thank you for your confirmation. Did you ever drive your TR6 with the supercharger - but the bypass locked / not working? Ciao, Marco Quote Link to post Share on other sites
Tim D. Posted March 7, 2023 Report Share Posted March 7, 2023 Hi Marco, Yes, my custom set up allows me to manually control the bypass. Obviously the car is pretty dull with the bypass permanently in place (8.5:1 CR and no boost) but with it permanently disabled (allowing 4psi boost) the extra torque is very obvious. I do wonder whether the bypass is really required as not all systems use it. Some have said that it reduces wear on the SC in the suck through configuration but I am not sure. What I do know is that the transition from bypass active to bypass inactive leads to a transiently lean condition which leads to slight hesitation. Tim Quote Link to post Share on other sites
Z320 Posted March 7, 2023 Author Report Share Posted March 7, 2023 hmmmm, I think to spend 300 Euro for a closer look on a used SLK 230 supercharger is not really wasted? Quote Link to post Share on other sites
Z320 Posted March 11, 2023 Author Report Share Posted March 11, 2023 The postman is my friend , let me and my "lucky pig" smile today... I think this could keep busy the next year. Ciao, Marco Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 11, 2023 Report Share Posted March 11, 2023 50 minutes ago, Z320 said: The postman is my friend , let me and my "lucky pig" smile today... I think this could keep busy the next year. Ciao, Marco Which carburettor are you considering? Quote Link to post Share on other sites
Z320 Posted March 11, 2023 Author Report Share Posted March 11, 2023 SU HD8, I hope a friend of mine has some in stock from his Jags and AH and borrows me one. Do you have another suggestion, please? Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 11, 2023 Report Share Posted March 11, 2023 (edited) 1 hour ago, Z320 said: SU HD8, I hope a friend of mine has some in stock from his Jags and AH and borrows me one. Do you have another suggestion, please? Thought you would say that. HS8 would be more useful as it has a mechanical choke mechanism. A lot of the Jag HD8 carbs used a solenoid controlled over fuelling device, that can be made manual, but would be easier controlled by lowering the jet rather that adding a richer fuel circuit from an external device. The HS8 looks like a bigger HS6 from TR4A. They were on Rover 2000 etc. and were THE tuning mod for Dolomite Sprint when Webers were not allowed. Do not forget you will need a larger capacity float chamber, as the sc might suck it dry on full throttle. Edited March 11, 2023 by BlueTR3A-5EKT Quote Link to post Share on other sites
Z320 Posted March 11, 2023 Author Report Share Posted March 11, 2023 Hi Peter, what makes me "worry" with my low budget is to buy a HD8 while I have a pair of TR4A HS6 and a pair of Strombergs in stock. Quote Link to post Share on other sites
Z320 Posted March 11, 2023 Author Report Share Posted March 11, 2023 Don't worry me or my Wife! The oily towel came with the SC Quote Link to post Share on other sites
Peter Cobbold Posted March 11, 2023 Report Share Posted March 11, 2023 Fabricating the manifold will be the main challenge, unless Moss will sell you one. The blower hangs from the bolts that secure the manifold to the head! One 2inch SU eg HS6 should do the task (unless you are aiming for >200hp and silly boosts and holed pistons... Peter Quote Link to post Share on other sites
Peter Cobbold Posted March 11, 2023 Report Share Posted March 11, 2023 That graph is from Allard's book on supercharging. More info in the talk I gave in Malvern https://supertrarged.wordpress.com/2015/08/10/iwe-tech-seminar-supercharging-trs-for-the-road/ (ppt file ) Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 11, 2023 Report Share Posted March 11, 2023 2 hours ago, BlueTR3A-5EKT said: Thought you would say that. HS8 would be more useful as it has a mechanical choke mechanism. A lot of the Jag HD8 carbs used a solenoid controlled over fuelling device, that can be made manual, but would be easier controlled by lowering the jet rather that adding a richer fuel circuit from an external device. The HS8 looks like a bigger HS6 from TR4A. They were on Rover 2000 etc. and were THE tuning mod for Dolomite Sprint when Webers were not allowed. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 11, 2023 Report Share Posted March 11, 2023 27 minutes ago, Peter Cobbold said: That graph is from Allard's book on supercharging. More info in the talk I gave in Malvern https://supertrarged.wordpress.com/2015/08/10/iwe-tech-seminar-supercharging-trs-for-the-road/ (ppt file ) Good to read your post Peter Quote Link to post Share on other sites
Peter Cobbold Posted March 11, 2023 Report Share Posted March 11, 2023 52 minutes ago, Z320 said: Hi Peter, what makes me "worry" with my low budget is to buy a HD8 while I have a pair of TR4A HS6 and a pair of Strombergs in stock. One of those 1 3/4 inch HS6 will do the job. But the over-run valve in the butterfly will need removing Peter Quote Link to post Share on other sites
Peter Cobbold Posted March 11, 2023 Report Share Posted March 11, 2023 1 minute ago, BlueTR3A-5EKT said: Good to read your post Peter Tks Peter. My fettling days are over, but it is good to see supercharging still creates interest. Its a pity Moss lost interest..... Peter Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 11, 2023 Report Share Posted March 11, 2023 4 hours ago, Peter Cobbold said: Tks Peter. My fettling days are over, but it is good to see supercharging still creates interest. It’s a pity Moss lost interest..... Peter I was told they lost supply of a vital part. Quote Link to post Share on other sites
Tim D. Posted March 12, 2023 Report Share Posted March 12, 2023 Over alternative is a twin barrel holley as I think Peter was alluding to. I have this on my moss setup and it works OK. It has to be modified by drilling the mixing block so that the post SC vacuum signal can be routed to the power valve on the Holley. Getting this done is a little challenging and moss couldn't source an contractor to do this which is why they stopped the kits. Personally if I was doing my own setup I think I would do EFI with injectors after the SC. Thus could be done on the moss setup by drilling the manifold and perhaps using the holley for fhrottle control. Tim Quote Link to post Share on other sites
Z320 Posted March 12, 2023 Author Report Share Posted March 12, 2023 Hi Peter, thank you for joinig here at this thread and your HS6 evaluation. This will safe me a lot of money and allows to rotate the SC down instead to hold it leveled for 2 HS6. But - 2 HS6 will look very impressive? And yes, the valves have to be out, these butterflys are only used in this case to hold all parts together. The Moss inlet manifold will not fit the SLK SC because it has a much shorter shaft. --> I have to place it more forward. The SC's weight is 8.5 kg and it I will not only fix it on the manifold and cylinder head studs. Also Moss fixes it much solid on the front end of the shaft on the engine. Allard's book you already recommended me and I own it already for some years. But it is no fun for me reading it, your seminar dokumentation helps me more, thank you. Next is to slow down and collect ideas. Ciao, Marco Quote Link to post Share on other sites
Z320 Posted March 12, 2023 Author Report Share Posted March 12, 2023 Hi Tim, I also gave EFI a few thoughts, shure Jochem colud help me. But I want to see a carb aand EFI doesn't fit to the small budget which I want to spend. Ciao, Marco Quote Link to post Share on other sites
Z320 Posted March 12, 2023 Author Report Share Posted March 12, 2023 (edited) Peter, back from my workshop you make me struggle: HS6 is 1 6/8“ (1.75“), HS8 is 1 8/8“ (2“)? Edited March 12, 2023 by Z320 Quote Link to post Share on other sites
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