Ian C Posted June 7, 2005 Author Share Posted June 7, 2005 I feel an e-mail to Cosworth coming on... I tried an email to Shell and that didn't work. I'm quite annoyed that this has gone from a very useful discussion on the artefacts of the stock sequential map and how it affects a single turbo conversion to Forced Induction Tuning 101... If anyone takes the advice to aim for 14:1 AFRs under boost, you deserve all you get. In my opinion.* -Ian *and everyone else involved in forced induction tuning since day one Link to comment Share on other sites More sharing options...
JohnA Posted June 7, 2005 Share Posted June 7, 2005 I... If anyone takes the advice to aim for 14:1 AFRs under boost, you deserve all you get. Anyone who reads my above post as a blanket recommendation to run 14:1 under boost, deserves what they get (holes in the pistons more likely they'll get ) It is only possible under specific conditions, like those I clearly stated. It was borne out of my own experience, and you'll need the right combination of water/methanol injected to replicate it (not too difficult mind you, model shops sell it a fiver per gallon) Neither is 11:1 a 'failsafe' AFR as some people want to believe. When mine went 'pop' last time it was richer than 11:1 Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 7, 2005 Share Posted June 7, 2005 John, no one said 11:1 was 'failsafe', things go wrong whatever the AFR, but your posts imply that running a 14:1 AFR at full boost is acceptable, which it clearly isn't, even with straight meth I wouldnt even attempt it, and knowing how unreliable WI pumps can be, It's just plain crazy. And what about adding lube to the Meth, or do we get to that later when someones seals have failed. A few of us are only really interested in road cars, but if you are happy running your car that lean, using WI/Meth as a Band Aid, at the end of the day its your car. Link to comment Share on other sites More sharing options...
JohnA Posted June 7, 2005 Share Posted June 7, 2005 .. your posts imply that running a 14:1 AFR at full boost is acceptable. yes, under the conditions I mentioned .knowing how unreliable WI pumps can be, It's just plain crazy.. well if you use ethanol or run it dry or whatever, then the pump will fail eventually, what do you expect? . And what about adding lube to the Meth, or do we get to that later when someones seals have failed. . what lube, it depends on the pump mate. The Shureflo pumps have different seals to the Aquamists for example. . A few of us are only really interested in road cars, but if you are happy running your car that lean, using WI/Meth as a Band Aid, at the end of the day its your car. Band Aid, oh dear... Terry, please keep this in PMs or emails Link to comment Share on other sites More sharing options...
Alex Posted June 8, 2005 Share Posted June 8, 2005 The post is still there, no apology either. John, no apology necessary, I realise you just hadn't thought about what you'd written re VVTi modifications and as you don't have one I guess you'd not know fully about them. So you don't need to apologise further. Back on subject. FOR ALL PEOPLE NON TECHNICAL READING THIS THREAD - PLEASE DO NOT RUN 14:1 AFR's ON YOUR CAR UNDER BOOST! If you do, take out an insurance policy on your engine first...it's not advised by any tuner (inc CW) to run 14:1 on boost. 14.7:1 is stoich - this is the AFR used at idle on all petrol cars - at idle it's perfect. ~13:1 is the AFR for NA RACE ENGINES I believe 12.7:1 is the AFR's used by RACE ENGINES on full boost, that arn't designed to last that long. 12.5:1 is the best AFR for a road car on boost - IF!!! IF!!! IF!!! You can guarentee, the weather, altitude, quality of the fuel and engine condition will not change. 11.8:1 Is the optimal for a Road setup because sometimes external influences will lean that off to 12.5:1 BUT it's safe. Supra's on stock turbo systems run HIGH EGT's the cylinders get very very hot and you get detonation. Detonation can be prevented by using fuel to cool the pistons. (It also requires a decent IC and some other bits). 11.3:1 Is the richest you want to run. Anything with a lower AFR will be losing power without gaining you any more protection - excess fuel can only help so much. If the car is too rich you'll get a form of hesitation similar to a missfire. Link to comment Share on other sites More sharing options...
Alex Posted June 8, 2005 Share Posted June 8, 2005 And even more back on subject. Terry, or anyone else who actually want's there engine to survive... I'm trying to workout where to aim for in my AFR's on my single. I have been aiming for a steadily richening map. would 12.5:1 be acceptable upto say .5-.7bar? or is it really a case of det can;s at dawn and see what works? (Still heading for 11.8's at 1+bar.) Link to comment Share on other sites More sharing options...
JohnA Posted June 8, 2005 Share Posted June 8, 2005 I see that the age-old practice of selective reading is still alive and well. If you chose to pick on a single word and generalise, go ahead http://www.max-boost.co.uk/stuff/arguing_on_the_internet.jpg Link to comment Share on other sites More sharing options...
Alex Posted June 9, 2005 Share Posted June 9, 2005 No it ramps up dependant upon the boost Chis, Difficult to say at 1 bar but probably around 11.8. BTW new test for Alex, the car is in positive boost now at 1600 rpm, and makes 3psi by 2000 rpm, top gear. 2.3psi at 2000rpm and 0.01bar at 1145rpm Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 9, 2005 Share Posted June 9, 2005 0.01 bar just doesnt count bud.... looking good though Link to comment Share on other sites More sharing options...
Alex Posted June 9, 2005 Share Posted June 9, 2005 What pressure do you want for +VE then? 0.1 in which case it's about 1750-1800rpm. Does seem to take an age and I can't really get it shifting any faster. I'm using double figure timing advance at that point...wouldn't like to push it further without det cans. Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 9, 2005 Share Posted June 9, 2005 Yeah that sounds about right, they spool very slowly that low down Link to comment Share on other sites More sharing options...
JohnK Posted June 11, 2005 Share Posted June 11, 2005 Back on thread: What do people think the target AFR's should be for 3rd gear (auto) 100% throttle from 1000 to 3000 rpm. High load spooling - getting nowhere fast. Also should you have a fair amount of fuel dumped in whenever hard acceleration is called for, eg. like an accelerator pump on a carb. My logs are showing an initial lean patch, but this maybe the gauge just catchhing up? Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 11, 2005 Share Posted June 11, 2005 John acceleration enrichment is good, cant comment on the E-Manage, perhaps Chis will. AFR's change dependant on Load John. Chis tested today 7 psi, 2500rpm = 13.0:1 AFR in mine. Link to comment Share on other sites More sharing options...
Ian C Posted June 13, 2005 Author Share Posted June 13, 2005 When using the E-Manage, the stock ECU deals with accel pump Good numbers Terry -Ian Link to comment Share on other sites More sharing options...
TLicense Posted June 13, 2005 Share Posted June 13, 2005 Here's a screenshot of the target AFR's that AEM aim for on the stock map. What are you're thoughts chaps??? Link to comment Share on other sites More sharing options...
Alex Posted June 13, 2005 Share Posted June 13, 2005 Not that I fully understand what I'm looking at but I'd aim for 12.5's to 6-7psi...then head for 11.7's. I'd also be looking for high 13's till 2psi. Though this is what you need det cans for...to find out where is knocks and need more fuel. Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 13, 2005 Share Posted June 13, 2005 What would you think I should be looking at with my BL single installed top and bottom range? Im playing catch up on the wideband AFR stuff and not 100% sure what Im looking at just yet.. Terry what is Safe and what is pushing it? Link to comment Share on other sites More sharing options...
Alex Posted June 13, 2005 Share Posted June 13, 2005 11.7's-11.3's (Owens' will have mapped it for that) Link to comment Share on other sites More sharing options...
TLicense Posted June 13, 2005 Share Posted June 13, 2005 Though this is what you need det cans for...to find out where is knocks and need more fuel. Or a knock control strategy (ducks) Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 13, 2005 Share Posted June 13, 2005 Tony correct me if I am wrong but does the AEM not datalog the stock knock sensors? Just wondered how accurate it is. Link to comment Share on other sites More sharing options...
Guest Usmann A Posted June 13, 2005 Share Posted June 13, 2005 Yep tel, it does, It sees 0-5V feedack to the ECU, thing is though as you need to tell it(define) to the system what actual knock is. This the proper way, so you push the timing until you see voltage spikes on the sensor logs, and then you know your rough knock limit. You can add fuel too, with knock%rich/volt table and howmuch ign timing retard per rev. If its setup properly,it could save ur ass ... Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 13, 2005 Share Posted June 13, 2005 That sounds a nice feature. Link to comment Share on other sites More sharing options...
CJ Posted June 13, 2005 Share Posted June 13, 2005 Without wishing to sound a complete numpty, what actually causes the "knock"? Link to comment Share on other sites More sharing options...
Guest Usmann A Posted June 13, 2005 Share Posted June 13, 2005 Terry S That sounds a nice feature Its ok tel,aint got a patch on some of the Fcons abilities though ... Link to comment Share on other sites More sharing options...
TLicense Posted June 13, 2005 Share Posted June 13, 2005 Without wishing to sound a complete numpty, what actually causes the "knock"? The "knock" that the knock sensors measure can effectively be caused by a number of things. The knock sensor is effectively a listening device that's bolted to the engine, and pics up vibrations. The engine is vibrating all the time though so the ECU is set up to filter out these "normal operating vibrations" so any unusual vibrations (or more likely sudden bangs) from within the engine it senses as "knock" and takes appropriate action. As to what causes these extra vibrations, your looking at pre-igntion or detonation. Detonation is the spontaneous combustion of the left over bits of air/fuel after the normal combustion. Pre-ignition is when the air-fuel mixture errmmm pre-ignites before the spark ignites the mixture properly. Either way it causes an extra "high speed" pressure wave, which shocks the piston. This shockwave travels through the engine block material and is picked up by the knock sensor. Well that's my take on it anyway... Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now