roboldham Posted April 17, 2003 Share Posted April 17, 2003 Hi folks My first couple of "hot" days with my supe. Normally SBCed up to 1.25+ on a cooler day. (uprated fuel pump and Optimax so all ok) Could barely make 1.1 even giving it some serious stick today. Is this normaly behaviour for the blowers? I would be interested to know the dynamics of this - as I would have thought boost pressure would be the same, but oxygen density would be lower perhaps. Any simple explanations please! R Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 17, 2003 Share Posted April 17, 2003 You're RIGHT, hot weather = less dense air........ > > just produces LESS boost (less 'air' to squish-up in the 1st place) not such a bad thing as LESS likely to blow anything up ! ? BAD thing 'cos less boost = LESS POWER ........ and now someone's TECHNICAL gumpf..... ? ? Quote Link to comment Share on other sites More sharing options...
Guest Usmann A Posted April 17, 2003 Share Posted April 17, 2003 Hot days= low boost, as you said the air is LESS dense, therefore MORE boost.I'm not 100% on that, so anyone feel free to correct me. I know a bit more but not sure if its right,,so ill wait and see...sorry not much help. But I did hear that height from sea level also affects density and therefore boost, ie up north its colder and especially in Scotland, they are up higher above sea level therefore the air is less dense=more boost....or is it that NA cars cannot cope at high sea levels therfore the turbo cars feel much faster than them, due to the turbos inducing the air and building a greater pressue from the outside, which NA 's cannot do. Not much help...also want clarififcation on this topic.. Kind Rgds Usmann aLI Quote Link to comment Share on other sites More sharing options...
lovatt Posted April 17, 2003 Share Posted April 17, 2003 i definately noticed a diffarence on the way home tonight ! i thought it might be because the AC was on but when i turned it off it still felt slugish ! i think my standard IC has seen better days though time for FMIC Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 17, 2003 Share Posted April 17, 2003 It was luvverly and cool at midnight last night ! ! ! = PLENTY of boostie-poohs;) Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted April 17, 2003 Share Posted April 17, 2003 There were some figures published last year, may have been on here but I think it was on the list. Tests on the same car showed a big difference, ISTR it was over 20% measured in the summer and then the winter. Quote Link to comment Share on other sites More sharing options...
roboldham Posted April 17, 2003 Author Share Posted April 17, 2003 I would be interested in getting the technical low down on all this. I am considering raising the settings in my boost controller to rectify - but could this cause problems with fuelling (too rich / lean) I suppose I would have to drop them again on cooler runs. Do people have hot and cold settings? Tell all! R Quote Link to comment Share on other sites More sharing options...
B3any Posted April 17, 2003 Share Posted April 17, 2003 Didnt someone say you lose/gain 2bhp for every 1 degrees celsius, Mine fels shit in this warm weather, dropping like yours Rob, from 1.25 to about 1.1bar. Quote Link to comment Share on other sites More sharing options...
Terminator Posted April 17, 2003 Share Posted April 17, 2003 If you have an under bonnet after market induction kit the problem will be exacerbated. This is one of the reasons I ditched mine and went back to the stock air box, with a panel filter. Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 18, 2003 Share Posted April 18, 2003 OH NO PHIL..... you'll start the BIG-CONE brigade off again ! ! Yours, "I-like-it-standard"-FatS. Quote Link to comment Share on other sites More sharing options...
Terminator Posted April 18, 2003 Share Posted April 18, 2003 I did say it was ONE of the reasons, but you are right Steven I should have said AIMPO. No opening shot intented. Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 18, 2003 Share Posted April 18, 2003 Actually I always fancy a 'King-Cone' (YES, and the ice-cream variety:p ). I like the looks under the bonnet, and, I'd like bit more induction noise ? (although, I also like QUIET when needed !). I just think it's so Mind-Bogglingly obvious that it's gonna' suck in hot air:conf: WHY would K&N have started doing 57i's ?? ALL they are is their standard Cone with a length of corrugated plastic pipe which you squeeze back in the ORIGINAL slot where the intake WAS and......wait for it..... POINT VAGUELY at the cones surface ! ? ! IF/WHEN I see one with a proper fresh-air intake system for me' Soop I will probably have one. (not TOO dear though;) ) FatS. Quote Link to comment Share on other sites More sharing options...
Guest Usmann A Posted April 18, 2003 Share Posted April 18, 2003 Steve "Boostie -poohs" pls explain yourself??? Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 18, 2003 Share Posted April 18, 2003 AH, sorry "U", it's a technical term..... OOMPH ? WAMMO ? clout ? Intake-Manifold-Pressurization ? Depends where you hark from I suppose ? being a ravin' loony I just can't seem to speak PROPPA English....OR, type it ! ! Quote Link to comment Share on other sites More sharing options...
Guest Usmann A Posted April 18, 2003 Share Posted April 18, 2003 Steve ur a 1st class act, , and I havent even met you:eek: , you going bolney?? Quote Link to comment Share on other sites More sharing options...
Alex Posted April 18, 2003 Share Posted April 18, 2003 Originally posted by u_ali Hot days= low boost, as you said the air is LESS dense, therefore MORE boost.I'm not 100% on that, so anyone feel free to correct me. I know a bit more but not sure if its right,,so ill wait and see...sorry not much help. But I did hear that height from sea level also affects density and therefore boost, ie up north its colder and especially in Scotland, they are up higher above sea level therefore the air is less dense=more boost....or is it that NA cars cannot cope at high sea levels therfore the turbo cars feel much faster than them, due to the turbos inducing the air and building a greater pressue from the outside, which NA 's cannot do. Not much help...also want clarififcation on this topic.. Kind Rgds Usmann aLI Is this what you meant?? Less air = less boost, not more. On a hot day you have to run more boost (ie turn up the EBC) to equal the boost you get on a cold day at normal boost levels. Hot days = better traction from hotter tarmac vs. loss in power Cold Days = no traction vs. more power.. you just can't win! Quote Link to comment Share on other sites More sharing options...
Guest Usmann A Posted April 18, 2003 Share Posted April 18, 2003 Yeah I think so, just read what I wrote and didnt put it very well, sorry, but whats all this stuff I read somewere about distance from sealevel affects boost, and kills NA's power.??is this true? Quote Link to comment Share on other sites More sharing options...
Alex Posted April 18, 2003 Share Posted April 18, 2003 Yes, the further above sea level your are the thinner the air....England though is a bit too small and flat to show up any significant differences. This is why climber have to take oxygen tanks with them when they scale Everest and why planes are pressurised. Not enough air to breathe up there. NA's suffer more as they can only take in normal atmospheric pressured air. Turbo's are able to force more in and turn up the boost and thus suffer less. That's why the Maclaren's and NSX's got whooped in the JGTC last year down the staights at (I think it was) Aida, its well above sea level and the turbo cars - the Supra's and others) just romped away down the straights. Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 18, 2003 Share Posted April 18, 2003 ALEX, I assume the Boost Guage shows ACTUAL boost ie. if there's less 'of it' then the guage READS lower ? Is it the same with the Boost Controllers' readouts ? It's just (I assume) that if you SET it higher on the controller it won't necessarily be able to REACH it - because of the 'less dense/ less boost'. ie. you SET it to 1.3 (~) in cold weather and it REACHES 1.3.. you SET it to 1.4 in hot weather and it still might only REACH 1.2 ? ? (but, it would READ 1.2 ? or read 1.4 - is it an actual boost guage ?) "Haven't-a-clue-NEVER-been-there-and-done-it-YET-FatS." ???????????? Quote Link to comment Share on other sites More sharing options...
Alex Posted April 18, 2003 Share Posted April 18, 2003 All boost pressure displayed is the Manifold pressure just prior to it being injested What I'm saying is that you would have to run say 1.4bar to get the same power as 1.2bar... BUT IT IS NOT RECOMMENDED!!!! Just face the fact you're going to lose some power for now, whilst you bask in the sunshine. I'd rather have more grip and a little less power!!! Quote Link to comment Share on other sites More sharing options...
Adam W Posted April 18, 2003 Share Posted April 18, 2003 If the air is thinner to start with it's at lower pressure. So your turbos have to work harder and do more rpm's to keep your boost pressure at the same level. In theory, because your wastegate reads off the manifold pressure, it should just open a bit later and you wouldn't notice the difference. I think having an electronic boost controller can help maintain proper boost levels but also confuses the issue slightly because you've already altered the wastegate/boost pressure system. Perhaps with a well set up EBC and a top notch external wastegate it wouldn't be a problem. You'd still lose power though because hot air at 1.3bar (or whatever) contains less oxygen molecules than cold air at 1.3 bar. I think . . . (Now I know why they don't let me mess with the gas cylinders at work!) Quote Link to comment Share on other sites More sharing options...
Guest Usmann A Posted April 18, 2003 Share Posted April 18, 2003 Cheers guys, I get it now! Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted April 18, 2003 Share Posted April 18, 2003 Remember if you up the boost on hot days to try and compensate for a loss in performance you are getting closer to detonation. Turbo's have to work harder to reach the boost you set, the air is hotter to start with therefore chamber temps and EGT's will be hotter. Be careful. Quote Link to comment Share on other sites More sharing options...
JamesG Posted April 18, 2003 Share Posted April 18, 2003 Originally posted by Steve W ALEX, I assume the Boost Guage shows ACTUAL boost ie. if there's less 'of it' then the guage READS lower ? Is it the same with the Boost Controllers' readouts ? It's just (I assume) that if you SET it higher on the controller it won't necessarily be able to REACH it - because of the 'less dense/ less boost'. ie. you SET it to 1.3 (~) in cold weather and it REACHES 1.3.. you SET it to 1.4 in hot weather and it still might only REACH 1.2 ? ? ???????????? I think you've nearly got it right. I can only speak for the Blitz DSBC but I imagine other ones work in a very similar way. The settings you make to control boost are a RATIO that controls the duty cycle of the solenoid (it turns on and off very quickly at a fixed frequency and the ratio controls the on time), and a GAIN that controls at what pressure the ratio starts to take effect (so the wastegate is held closed to build boost quickly). These are set up for the individual car to hopefully hold boost at the desired level. There's also a boost limit that you mentioned. This will subtract from the ratio by a given value if the limit is exceeded. I don't think this is intended for holding the boost at a certain limit under normal driving, but more for a "last resort" for conditions such as boost spikes. Mine is set up at about 1.3 bar and beeps very loudly if it goes above this value. What Adam wrote about the temperatures sounds spot on to me. James. Quote Link to comment Share on other sites More sharing options...
SMW Posted April 18, 2003 Share Posted April 18, 2003 I was out in the car fairly early this morning and it felt as it normally does with a big hit when the 2nd turbo joins in:D Went for another spin early afternoon and what a difference! Felt much less responsive compared to earlier. A small price to pay for the glorious weather I guess. Quote Link to comment Share on other sites More sharing options...
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