Mark Ayling Posted July 28, 2003 Share Posted July 28, 2003 Sorry to start another thread with this in, but I wanted to get some technical input. Looking at my dyno printout, can anyone tell me how I could reduce the massive drop in torque between turbos? Also any other opinions/advice welcome! Cheers. http://www.mpaconsultancy.co.uk/supra/DYNO-2003-07-27.jpg Quote Link to comment Share on other sites More sharing options...
Nathan Posted July 28, 2003 Share Posted July 28, 2003 Hi Mark, I'm convinced that theres a problem somewhere. Not only due to the torque loss but more importantly the length of time it's there for. A dramatic drop from 3K to 5.5K is not right. Are you happy with the boost controller fitment and setup? What is the boost doing in this rpm range? The graphs show what could also be a very lazy No1 turbo. The lightswitch power delivery, doubling in the space of 500rpm must be interesting in the wet. Ever considered a big twin.... Regards, Nathan TDI PLC Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Hi Nathan, Pete was amazed at a) how late the second turbo was and a) how hard it kicked in when it eventually did! Basically, it used to kick in at 4000-ish rpm, then I had my fuelling/boost controllers (S-AFC and AVC-R) set up recently by Leon, which also ended up meaning a new ("race") fuel pump... I don't mind it being late as you can get used to when it kicks and use the gears accordingly, I'm more concerned about whether that entails a problem or not. Its definitely interesting in the wet, especially with the bald tyres I have on the back at the moment!! I have to admit as well, having it like that does make a big twin/single appeal to me more than before, you can't beat such a great surge of power! (if I could afford it that is!) Not sure what to do next.... Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted July 28, 2003 Share Posted July 28, 2003 What FCD do you have Mark ? Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Originally posted by Martin F What FCD do you have Mark ? It turned out, when Leon started setting my car up, that I didn't have one at all - so I now have a brand new TRL FCD.... Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted July 28, 2003 Share Posted July 28, 2003 OK, probably not that then. Just that i have heard that the HKS ones can give a pronounced drop like that between the two turbos due to not pre-spooling turbo two correctly. Quote Link to comment Share on other sites More sharing options...
THOR Racing Posted July 28, 2003 Share Posted July 28, 2003 For those of you not familiar with the Dynapack graph for Torque, you take the figures displayed and divide by the final drive ratio (in this case 3.4) to get 440Nm (324.5 lb-ft) Also the peak was 382.8BHP and not the 374BHP listed at the bottom (this was a marker on a previous run) Plus all the BHP figures are at the hub and are DIN corrected. Regards Pete Quote Link to comment Share on other sites More sharing options...
Adam W Posted July 28, 2003 Share Posted July 28, 2003 Pete, do you have any idea of the difference between at-the-hub and at-the-wheels figures? Quote Link to comment Share on other sites More sharing options...
Nathan Posted July 28, 2003 Share Posted July 28, 2003 Originally posted by Martin F OK, probably not that then. Just that i have heard that the HKS ones can give a pronounced drop like that between the two turbos due to not pre-spooling turbo two correctly. Never heard of that one, and if they did I very much doubt that they would even make the drawing board if they gave results like Mark has. Every pre-spool problem I have seen has been down to the plumbing of the boost controller, not the FCD used. I believe Leons 'race' pump is a Walbro GS342, the same as we use. That should be fine for your use. Still, the power and torque curves you have are deffo not right. I would be looking at rigging the 1st turbo to run max boost and see what it makes. It's possible that it's low on boost or even failed completely. 200bhp max before the 2nd comes in would indicate such... Thats why I asked what boost you are making on No1. If you're still seeing 1 bar then the turbo would seem to be OK and I would be looking elseware. There has to be a reason for why the car is so low on power up to 5.5K. Regards, Nathan TDI PLC Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Thanks for your input - I'll have a look at my boost gauge/controller on the way home this evening and see what No. 1 is peaking at. Could it not also be that the AVC-R is not set up in the best way - I know very little about it but I am aware that you can specify boost/duty individually throughout the revs range....? Quote Link to comment Share on other sites More sharing options...
Nathan Posted July 28, 2003 Share Posted July 28, 2003 Originally posted by Mark Ayling Could it not also be that the AVC-R is not set up in the best way - Yep, just what I said in my 1st post..... Like you say, see what the boost is doing on No1. Until then, we're not really going to get anywhere. Cheers Nathan. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 28, 2003 Share Posted July 28, 2003 Mark if you don't mind the late delivery try the true twin conversion. It will make the torque more linear. Think Matt H can do this via a switch now so you get the best of both worlds. Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Originally posted by Terry S Mark if you don't mind the late delivery try the true twin conversion. It will make the torque more linear. Think Matt H can do this via a switch now so you get the best of both worlds. Nice! I'd be interested in giving it a go. Only question is (and bear in mind I'm completely non-technical) would the fuelling and/or boost controller have to be set up different for TTC? In other words, is there more to it than just flicking a switch? Quote Link to comment Share on other sites More sharing options...
dude Posted July 28, 2003 Share Posted July 28, 2003 Err Guys This late 2nd Turbo/lightswitch delivery sounds like my problem which seems to come and go (2nd in at 5000rpm) and seems to be overcome by stamping the throttle pedal really hard , i also can get it to cut in by manually inputting an earth to the 2 rear vsv's at 4000rpm , it is driving me mad as its so nice to drive when its right but a pain when it comes in that bit later , im gonna swap to a single eventually but i'd love to find the cause of this . John:flame Dev Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 28, 2003 Share Posted July 28, 2003 You want to take off your high heels Dude:p If it is OK when you "Stamp" on the pedal, it sounds like a reading from the TPS(throttle position sensor). Maybe some hair from your chesst is stuck under the throttle? Seriously though, I think Leon has a Techtom unit for the OBD1 cars. If this shows the TPS % then it may shed some light. Mark fuelling would be a little rich low down and the ignition a little retarded ( Dude?). So pretty safe really Quote Link to comment Share on other sites More sharing options...
Wez Posted July 28, 2003 Share Posted July 28, 2003 Does this occur when driving very hard? I have found that if I floor my car from say 2000 - 2500 then it goes like S**T of a shovel all the way through the rev range and the second turbo cuts in about 3800 - 4000 with nice delivery of power etc. If i am driving normally and then punch the throttle after approx 3800 it sometimes takes a long time to pick up. I must add that it doesn`t do it everytime either and looking at the boost it doesn`t always look like both turbos are going full song. Sound similar? :flame Dev Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Right - I kept an eye on the gauges on the way home just a minute ago, and the first turbo seems to peak at 0.7 - 0.8, the second turbo kicks at about 5000-5500rpm and peaks at 1.2. Sometimes the peak-hold shows 1.25 but I guess it will vary depending on atmospherics...? These are the settings on my S-AFC and AVC-R: http://www.mpaconsultancy.co.uk/supra/apexisettings.jpg Any comments from the technical peeps? Any help would be much appreciated! TIA Quote Link to comment Share on other sites More sharing options...
dude Posted July 28, 2003 Share Posted July 28, 2003 Originally posted by Terry S You want to take off your high heels Dude:p If it is OK when you "Stamp" on the pedal, it sounds like a reading from the TPS(throttle position sensor). Maybe some hair from your chesst is stuck under the throttle? Seriously though, I think Leon has a Techtom unit for the OBD1 cars. If this shows the TPS % then it may shed some light. Mark fuelling would be a little rich low down and the ignition a little retarded ( Dude?). So pretty safe really Im not retarded my fine smokey friend in fact quite the opposite hence the need for leon to fit the timing thingy to pull me back at the top end John:flame Dev Quote Link to comment Share on other sites More sharing options...
dude Posted July 28, 2003 Share Posted July 28, 2003 Terry i'll let you have a drive at the weekend , it may frighten you a little but you'll just have to live with that if you wanna hang around with the big boys . John:flame Dev Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 28, 2003 Share Posted July 28, 2003 Your AFC settings look bizarre, it appears the only thing it is set up to do is *lean* the mixture off at larger throttle openings. I don't understand why that would be set up and yet the low throttle openings isn't changed at all? 0.7bar on turbo1 sounds about right, by the way. -Ian Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Dude, GET ORF MOI THREAAAD!! Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 28, 2003 Author Share Posted July 28, 2003 Originally posted by Ian C Your AFC settings look bizarre, it appears the only thing it is set up to do is *lean* the mixture off at larger throttle openings. I don't understand why that would be set up and yet the low throttle openings isn't changed at all? 0.7bar on turbo1 sounds about right, by the way. -Ian Well due to my limited technical knowledge I don't understand it either! The only changes to the stock J-spec fuel system are the pump and the FSE valve.... Quote Link to comment Share on other sites More sharing options...
Adam W Posted July 28, 2003 Share Posted July 28, 2003 My understanding was that the ECU would ignore any SAFC changes in the closed loop part of its running, ie the low throttle settings. Therefore it was best to leave them all at zero. However, when I lat had mine mapped by Leon the changes to the low throttle map totally transformed the driveability of the car (for the better) and even after 1000miles there was no sign of the ECU throwing a wobbly or anything. Quote Link to comment Share on other sites More sharing options...
dude Posted July 29, 2003 Share Posted July 29, 2003 I have the walboro pump,550 injectors and presure reg and i believe my SAF-C is set up to allter at higher revs as the closed loop part of the ECU should control everything lower down , mark have you tried manually operating the vsv's at 4000rpm ???? John:flame Dev Quote Link to comment Share on other sites More sharing options...
dude Posted July 29, 2003 Share Posted July 29, 2003 BTW Mark your 2nd turbo symptoms are allmost identical to mine , ive disconected the boost controller and they are the same , like i said it seems to come and go so i reckon its electrical . John:flame Dev Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.