I'm mid way thought doing a bit of research into my engine rebuild and coming across these as well as scraper plates I know there designed to stengthen the bottom end from various twisting forces, the main research I have comes down to the main journals able to flex stightly under load this seems to course uneven wear which makes the crank feel out of balance I have also come across 12.9 bolts designed for the just main caps to allow more/same clamping force for less lateral movement I've read many threads on a geeky TDI forum, with no real conclusion on how benifical theses are on high torque engines the questions I have how effective are these on low reving engines with high torque TDI engines? Whos used these in the past can they be picked up for sub 200? anything else worth taliking about?
It's something I'm cosidering looking into for the product range. The blocks can suffer with cracking at the lower rear edge at the gearbox end... up from the large round hole on the flange. My own block has done it (1800 race/high rpm), and I've seen it on 2 others (long & short rod 2ltrs, high power & fast road), and heard of it happening on a standard engine as well... so there an issue with stress of some sort. I'd say 200 or a bit under should be possible.
The factory VAG engine caps are poorly supprted leading to this product being available. However, fittingthem requires precision machining for exact fitment. Not a bolt in job from what I have seen? Gurds
there was a thread on vwcaddy for a groubuy on them but i'm not sure if they took off, its was a 50/50 spilt on the real need for them http://www.vwcaddy.com/showthread.php?t=39244 http://www.vwcaddy.com/showthread.php?t=45628&highlight=girdle
I have heard of it in various VW engines used at high revs, and many reports in TDI engines with higher boost, hence me wanting gto deal with it during the rebuild Yes I beleive so, but I surprise myself with my angle grinder skills, and a tape measure... I'm also wondering how it sits bolting on a scrapper plate as well look like thats the mk3 block kit on there, see what you mean about 50/50 split I've not looked at them stripped down, but later diesels seem to have a balance shaft bolted in the area - wonder if it doubles up as gridle!
The girdle in the first post isnt worth a damn(In my opinion). Sorry if any sponsors on here sell them. But they need to be far thicker than that to make any added difference.
The Block in the picture is also fitted with Billet Steel Main Caps Is it the Rosten Performance one in the picture ? http://www.rosten-performance.com/ All the people i know running 500 + BHP have Girdles fitted to their 20v Blocks but as brian says much thicker gauge than this one. ARP Main Cap Studs All fitted Billet Main Caps http://www.intengineering.com/IE-Billet-4140-Tall-Boy-p9505749-1-2.html
I was reading about these in a book at lunchtime today as it happens, an altogether meatier prospect cast (for the rover v8) by Janspeed in the 1970's: Incorporating the main caps and dry sump pan, for maximum rigidity. Would need line-boring though.
IMO they make a big difference; stiffening the structure by supporting the main cap bolts at both ends, instead of just one and linking the main caps together as one, like a bearing ladder. However, stiffening is not always the best solution to dealing with forces. Stress in modern engines is more likely to be dealt with by stretching to accomodate the forces, rather than ridgidly opposing them.
Id normally bite my tongue and go with the flow as Im not into rowing online, but what you said does not hold true when block stiffness is taken into account. The top girdle is a waste of money and I could bend either section by standing on it. The caps get into a 3 dimensional plane wobble that kills the oil film. The above girdle cannot stop that. Id call it an overkill scraper, rather than a useful girdle. Below is a picture I got off net that is well hidden, but its in the public domain so Im sharing, its of cast iron construction, for a turbo's engine running at the limit, look at the thickness, even at that, the designer is still experiencing flex and has redesigned the whole thing to a full cast sump/ladder like the Btcc 16v engine. You cannot have a block stiff enough in that area. The thread that the picture was taken was nothing really to do with vag girdles, It just came up in passing, and the rest of the thread is of no interest to the discussion in hand. Alex, Im gonna make on of them soon, ''just to see how it feels''
A mix of the one alex shown and the one you show brian Would be awesome I was about to contact you to make something Like that I dont know if you ever seen the oettinger sump which is in two Parts but if you add the main cap to the upper cap you got a winner IMO Any good engine blueprinting need lign honing To check if the bock is square
http://performance-diesel.com/index..._id=19&zenid=68450040def5323e937d3114d6d84186 This is a bit more like it for block stiffening, 1/2" steel, and as with most of these requires machining but par for the course really. Pricey though.
I've had a good read on this thread, I'm going to pick up something out off the VAG shelf by weekend if I can find more info via internal VW channels to see the comparisions I under stand the underlining reason for fitting these, my original 1st post is a eurospec item surley a girdle even at a couple mm thick, when all bolted up joining all main caps and securing them with the sump to block will help cut down on flexing/movement far more than none at all??
In some planes more than others, the quaility, dimensions and fit of the spacers between the plate and main bearing saddles will probably have the biggest (detrimental) effect on the overall performance IMO.
the original thin one pictured may stop some movement but only in 1 plane, once it's running and all the twist and virbrations will set up more movement in 3 dimensions. you'd need something with greater torsional rigidity like this ideally if in doubt make a cardboard one and twist it in your hands
So what we're saying is it will still try to lift the caps and also shift them fore, aft and sideways. The analysis IMO here applies to the most ludicrously tuned engines, but keeping it real with an "answering-to-demand" question: would it be possible to make a non-bearing wet sump version that does everything the dry sump version does, and avoids the oil pump? Or are the bolts getting too long by that stage and moving into the realms of stretch?
sure you could do with some clever bolt recesses and sealing rings. but a 2 peice one would probably be best. However, this kind of work is probably only worth while on things that would ideally want a dry sump kit too. as many track 16vs have survived well without a girdle. Only really needed for those doing the big revs or big boost
Surely there must be substantial differences in the internal forces created in diesel and petrol, and also turbo and NA engines. 1.8Ts can snap oem rods at low rpm if cylinder pressures are too much. I presume TDIs with their monster torque are in this same area of high forces at lower end of the rpm scale. They have stronger rods and gudgeon pins, but seem to be using basically the same block as the petrols. And then the very high revving NA engines will be creating a different set of problems needing addressed in block stability. I am sure balance and harmonics will be coming in to play with all this at some point. I think it will only be the very high end outputs of either torque or revs that will need this sort of thing. The standard TDI diesel torque output is rarely if ever seen by any of the VAG NA petrol engines.
totally with you on that Danster, interesting stuff on minis recently total crank redesign to move vibration around leads to less flex at 8400 rpm & more power swiftune link from one of BrianGs theads on engtips there's more going on here than us laypeople know about, shame we don't see trendy tramp on here anymore as he designs engines and can explain stuff to mortal folk like me
If the whole block is twisting then the main caps will be moving and twisting relative to each other. The one plane when the thin girdle is strong will reduce this, hence stabilising the floating ends of the main caps and assisting block rigidity. Like a lower strut brace. Without doing any measuring or maths i would guess the girdle is somewheres in the region of 125 times stronger in that plane, than in the weakest plane.
