msupra1 Posted June 24, 2014 Share Posted June 24, 2014 I recently made some changes to my single setup. I use to have an HKS BOV mounted right close to the throttle body. I got a new Tial 50mm, it seemed too large to put there because of the battery. The easiest place to put it was as pictured. There is a coupler running from it directly to turbo, and then a coupler running to the intercooler pipe. The couplers are kind of bent as I re-used them from my last setup. The car should be spooling around 4200rpm I estimate. Its a 66mm turbo, .91 twin scroll on twin scroll mani.. 3" downpipe, ARC 2 row intercooler. if I do a pull in 3rd gear it might not hit boost till about 5000-5500rpm. I just feel like the spool-up is very sloppy. Other times I did a pull in 4th and it did spool around 4200rpm. I can't do it much since I'm breaking the new clutch in still. Is it because of the BOV location, or is the BOV location fine? Or is it because the couplers are a little bent and not flowing efficiently? Also the IC piping is steel, and BOV is aluminum. The only other possible location I can mount the BOV is in the lower turbo side piping. Is this going to be beneficial? cheers http://postimg.org/image/i12fg8df3/ Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted June 24, 2014 Share Posted June 24, 2014 I cant see the BOV location making any difference to turbo spool, i had my Tial BOV in exactly the same location, running a GT4088 and could make 14psi boost at 3,600RPM no problem, have you changed anything else engine wise? a lot of things can influence boost. Quote Link to comment Share on other sites More sharing options...
msupra1 Posted June 25, 2014 Author Share Posted June 25, 2014 (edited) Previously I was running a T3 housing on T3 manifold.. on this S366 turbo. It was getting full spool at 3500rpm. Very fast spooling setup. All I really had done was changed to the new .91 twin scroll T4 housing along with T4 mani. I had a new 3" downpipe made as well. I'm running the same 40mm wastegate as before. The couplers have a certain degree bend to them, but they are bent quite a bit, especially the one running directly to the turbo which is not that visible in the photo. Is this possibly causing the issue? I made a pull today in 3rd gear... nothing happens, and then around 5rpm is starts to build boost fast and spools afterwards In 4th when I did a couple pulls it managed to fully spool by around 4200. Possibly some beat leak going on? or is this coupler issue I'm describing maybe the issue? i'll be dropping the car by a friends shop to see what he thinks Edited June 25, 2014 by msupra1 (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 25, 2014 Share Posted June 25, 2014 I am always amazed why people run a BOV at all. If you don't mind the compressor stall noise they are just extra weight and something else to go wrong. I have not run a BOV on a turbo engine of mine for nearly 30 years. Quote Link to comment Share on other sites More sharing options...
Mk4Gaz Posted June 25, 2014 Share Posted June 25, 2014 Chris, there's a lot of controversy in the mr2 world, about not running a bov. What are the implications on stock jspec twins, being ceramic turbines? Does the compressor stall risk ruining them faster than running a bov, and should a non bov setup be kept for uk spec twins and/or single setups? Quote Link to comment Share on other sites More sharing options...
Mk4Gaz Posted June 25, 2014 Share Posted June 25, 2014 Regarding the op, it sounds like a boost leak, it's taking longer to spool as it's having to build more pressure to compensate for what's being lost? Maybe a boost smoke test would help? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 25, 2014 Share Posted June 25, 2014 (edited) I would have no hesitation using no recirculation or blow off valve on any turbo. They were solely introduced into mainstream engine production, by Bosch, to stop customers hearing what manufacturers believed were noises that they would not like, or perhaps understand. They make no difference to spool, and may indeed even increase spool time, and all the true experts I have spoken with believe they have no bearing on turbo life. Both 24 or 48 hour endurance race cars like older Group C turbo monsters, and current F1 turbo engines run no BOV. If they gained reliability or performance one or the other would have run them, for sure. IMO most people run externally venting valves as they are still big kids and like the attention they bring, the same as noisy exhausts. After a string of endorsements in my teens I rapidly became of the opinion anything you can do as a motorist to *NOT* attract attention is good for your driving licence Blaring exhausts, whooping BOV's and the like must be manna from heaven to PC Plod hiding in the hedge with his damned radar gun un-holstered. And with a vast swathe of residents now seemingly specialising in moaning about whatever someone else does, they cause friction when you are heard going in or out at what they deem unsocial hours. Edited June 25, 2014 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted June 25, 2014 Share Posted June 25, 2014 Previously I was running a T3 housing on T3 manifold.. on this S366 turbo. It was getting full spool at 3500rpm. Very fast spooling setup. All I really had done was changed to the new .91 twin scroll T4 housing along with T4 mani. I had a new 3" downpipe made as well. I'm running the same 40mm wastegate as before. The couplers have a certain degree bend to them, but they are bent quite a bit, especially the one running directly to the turbo which is not that visible in the photo. Is this possibly causing the issue? I made a pull today in 3rd gear... nothing happens, and then around 5rpm is starts to build boost fast and spools afterwards In 4th when I did a couple pulls it managed to fully spool by around 4200. Possibly some beat leak going on? or is this coupler issue I'm describing maybe the issue? i'll be dropping the car by a friends shop to see what he thinks I am wondering if its down to the turbine/housing change, is the .91 the turbine trim? and what is the A/R of the housing? the larger you go generally the slower you build boost. Quote Link to comment Share on other sites More sharing options...
marc_p Posted June 25, 2014 Share Posted June 25, 2014 I am always amazed why people run a BOV at all. If you don't mind the compressor stall noise they are just extra weight and something else to go wrong. I have not run a BOV on a turbo engine of mine for nearly 30 years. No BOV on mine, if your running an s366(same as mine), then it's an anti surge housing so made with the intention of not running a BOV. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 25, 2014 Share Posted June 25, 2014 I know that sudden pipe direction change, or pipe section change, should be avoided for as far as practical from the compressor snail's exit. Quite how radical a difference having the valve so near the compressor would make to on boost flow I wouldn't know, but surely it's simplicity itself to remove the BOV altogether, and replace it with a straight pipe section, and see if the fast spool returns? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted June 25, 2014 Share Posted June 25, 2014 I'm still a big kid then! although a rather old one;) I still like the sound of a BOV (if its not too truck like) and turbo stall, but i hate loud exsausts......... unfortunately i have to be content with the sound of a diesel turbo these days:cry: Quote Link to comment Share on other sites More sharing options...
msupra1 Posted June 25, 2014 Author Share Posted June 25, 2014 (edited) Yes its T4 .91 A/R divided housing I was just out with the car tonight. I did pulls in gears 1st gear - boost is nearly no where to be found 2nd gear - full boost around 5500rpm 3rd gear- full boost around 5000rpm 4th gear- full boost around 4300rpm 5th gear - give or take about the same as 4th, maybe 100rpm less I understand the boost is not supposed to come on in 1st like the other gears.. but in 2nd I'd expect it to normally. Sounds like some kind of leak? previously, my turbo would also make a constant turbo spool up sound, now you can't practically hear it until its about to spool. On my old setup when I floor it, turbo was boosting strong right at 3500rpm. I know the larger turbo housing shifts the power band over to the right but I can't live with this setup. Edited June 25, 2014 by msupra1 (see edit history) Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted June 25, 2014 Share Posted June 25, 2014 I would say its down to the 91 A/R turbine housing, what the trim on the compressor? have a read here, http://www.turbobygarrett.com/turbobygarrett/wheel_trim Quote Link to comment Share on other sites More sharing options...
msupra1 Posted June 25, 2014 Author Share Posted June 25, 2014 (edited) It's a 66mm. It's a Bullseye turbo, rebranded Borg Warner S366. American turbo, not sure if these are known in the UK. Very popular and reliable turbo. Perhaps I will remove the blow off valve, put pipe in there, go for a drive and see what happens. A thought is that the BOV is not functioning as it should and the system is not building up enough pressure for an efficient spool-up time. When I opened my bonet, this is how the BOV looked with the engine running. Is this normal? The metal piece moves up and down of course, but this is what I've been noticing. http://postimg.org/image/bxb0tc6of/ If all else fails, and everything is good.. I'll have to sell the turbo for a 62mm. But as mentioned, on my previous housing, I was making 3500rpm full spool in all gears, excluding 1st. The spool up time I have now is straight garbage. Edited June 25, 2014 by msupra1 (see edit history) Quote Link to comment Share on other sites More sharing options...
Sukhy Posted June 25, 2014 Share Posted June 25, 2014 No BOV on mine, if your running an s366(same as mine), then it's an anti surge housing so made with the intention of not running a BOV. Sorry to be a little off topic but are you still getting the chatter/turbo stall sound? Quote Link to comment Share on other sites More sharing options...
Guigsy Posted June 25, 2014 Share Posted June 25, 2014 I don't run a bov. I'd try it without and see what happens. Quote Link to comment Share on other sites More sharing options...
marc_p Posted June 25, 2014 Share Posted June 25, 2014 Sorry to be a little off topic but are you still getting the chatter/turbo stall sound? Yeah, but it doesn't bother me, it sounds a lot better than a BOV. Quote Link to comment Share on other sites More sharing options...
Ric Posted June 25, 2014 Share Posted June 25, 2014 When I opened my bonet, this is how the BOV looked with the engine running. Is this normal? The metal piece moves up and down of course, but this is what I've been noticing. If your engine was at idle there, that BOV looks open, which it should not be while the engine is running. It should only open when you lift off.. If its open constantly it will act like one massive boost leak, try removing it, or closing it. Quote Link to comment Share on other sites More sharing options...
Sukhy Posted June 25, 2014 Share Posted June 25, 2014 Oh yes definately. I'd rather run without a BOV. Quote Link to comment Share on other sites More sharing options...
mattdavies Posted June 25, 2014 Share Posted June 25, 2014 Do you have the dump valve plumbed into the correct source ? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted June 25, 2014 Share Posted June 25, 2014 Some BOVs have the spring pressure set to low and will open during idle, however because the vacuum that momentarily pulled during closed throttle will be of higher depression it will cause the dump. Quote Link to comment Share on other sites More sharing options...
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