DIY_EFI Digest Tuesday, 22 July 1997 Volume 02 : Number 246 In this issue: Re: L-jet problem RE: Aftermarket stand-alone systems Re: SWITCHED EPROMS Re: ECU Turbo Control Re: SWITCHED EPROMS Re: eproms via lpt Re: eproms via lpt analog or KISS EFI Best? Re: analog or KISS EFI Re: analog or KISS EFI Re: analog or KISS EFI Re: analog or KISS EFI Re: analog or KISS EFI RE: Throttle body sizing Re: analog or KISS EFI Re: analog or KISS EFI Re: Throttle body sizing Re: analog or KISS EFI See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Chief Date: Mon, 21 Jul 1997 09:41:52 -0400 Subject: Re: L-jet problem At 05:54 PM 2/26/97 +1300, you wrote: >The problem is that your injectors have stuck. What you want to do is pull them out and individually apply 12 volts across them. You should here a audible click. Do not hold the 12V supply on continuously as you will over heat them and possibly burn them out. If this does not work them take all 4 injectors down to an injector specialist to get them cleaned and freed up. If you do get them freed up then it is a good idea to soak them in some sort of injector cleaner for a while as what causes them to stick is the fuel left in them has dried up leaving a varnish type substance. > >What are the specs on your spyder. I have both a Fiat 124 sport(currently selling) and a Fiat 128 with a roof cut. I plan to buy a fiat 850 coupe and fit a suzuki G13B motor (1300-16 valve) into the back. I am looking at using a PC notebook style fuel injection system and do a little hoon car. At the very least it should be fun. > >Paul > >>The problem is the thing starts and then dies immediately. I have >>determined the only fuel it is getting is from the cold-start injector. >>Unplug it and the car doensn't fire at all. Hi Paul. It has been a long time since this message was sent but I got the Fiat running. Verdict - bad TPS. I did the 12V thing to free up the injectors also. Now to get the thing road ready. Thanks for all your help. How are you doing on your current Fiat projects? Ed Hilker aka "Chief" 84'SS - 700R4 ------------------------------ From: John Hess Date: Mon, 21 Jul 1997 09:04:55 -0500 Subject: RE: Aftermarket stand-alone systems IF I would like more info. Please post it. I am sure that ALL on this board would be interested. I wouldn't be here, otherwise. Haven't talked to a New Zealander in a long time (since the Vietnam "Conflict" days). Used to see quite a few of you in Thailand. >---------- >From: Simon Quested[SMTP:questeds@xxx.nz] >Sent: Sunday, July 20, 1997 4:32 PM >To: diy_efi@xxx.edu >Subject: Re: Aftermarket stand-alone systems > >Hi All > >> I've been reading up a bit on a several stand-alone efi/ignition >> systems, such as Electromotive's TEC-II, Accel's DFI, Haltech, and >> Motec. Of all these, I only have relatively complete information on the >> TEC-II. To install it, though, I'd have to replace most of the existing >> Bosch sensors with GM ones and I don't want to do that. I would prefer >> to find a stand-alone system that will adapt itself to the Bosch >> equipment already in place. > >There is a local company here in Christchurch Link that make a very >good aftermarket kit it does fuel/ignition and works happly with >bosch sensors. >If you want more info mail me > >Cheers > >Simon >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Simon Quested (E-mail questeds@xxx.nz) > Computer Technician, Silicon Graphics & Windows NT Support > Centre for Computing and Biometrics > LINCOLN UNIVERSITY OF NEW ZEALAND > Phone (64)(03) 3252811 Ext. 8087 >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >http://www.lincoln.ac.nz/ccb/techs/simon/default.htm >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >If voting could really change things, it would be illegal. >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > ------------------------------ From: "Robert W. Hughes" Date: Mon, 21 Jul 1997 09:54:24 -0700 Subject: Re: SWITCHED EPROMS Hi, Justin, it's me again. I saw your circuits for the multi-table eproms and would like to make a suggestion. Instead of a pull-down resistor and a switch to Vcc use a pull-up resistor to Vcc and a switch to ground. Switch open=1, switch closed=0. This is a better match to circuit requirements (inputs are usually current sinking) and gives a more reliable system with less chance of noise problems. - -- Robert W. Hughes (Bob) BackYard Engineering Houston, Texas ------------------------------ From: Orin Eman Date: Mon, 21 Jul 1997 11:20:32 -0700 (PDT) Subject: Re: ECU Turbo Control > I am trying to work out how the boost map works in a Subaru EJ20 > engine. I have the addresses of the boost maps (There is two for some > reason). I have created some 3-D surface graphs of these maps, which > yield nice smooth surfaces which indicate that I am on the right > track, but I can't quite work out how they work. My only method of > testing is to burn eproms and try new boost maps, but this is slow. I > have altered the boost by altering these maps, but have not been able > to successlfully get the boost I want yet. I suspect that the x and y > axis of the maps might be combinations of engine load, revs, throttle > postions, Map sensor output etc, but testing to work it out is slow. > Does anyone have an idea of what these axis might be? Has anyone Engine load, MAP sensor output, current boost are all essentially the same thing and probably aren't an input. One axis is almost undoubtably RPM. I'd guess the other is intake air temperature, though throttle position is a possibility. > modified boost maps in ECU maps in different cars, and has an idea of > parameters might commonly be used for the boost map axis'? It is also > possible that both maps alter the boost, or one controls overshoot, or > anything!! Yes, I have modified the Audi 5000 boost maps. Boost is controlled by a spring and the computer. The computer only increases boost if the throttle is more than 2/3 open and engine temperature is OK and the engine isn't at the limits of the knock control. The map is RPM based only and is desired boost for a given RPM. Are you sure those are boost maps and not ignition timing? The Audi computer has two ingition timing maps, one for premium fuel and one for regular. It switches between them depending on engine knock. The axes for these maps are RPM and MAP. Orin. ------------------------------ From: Frederic Breitwieser Date: Mon, 21 Jul 1997 09:09:01 -0400 Subject: Re: SWITCHED EPROMS >i have found the these to work fine in the P4 and also in TECH-1 >cartridges. if you use the same base code and only change the data of I liked your design, however I wish to submit the following comments. Instead of using SPST switches directly attached to the E/Eproms, its important to make them bounceless, whereby when switching, the real millisecend on/off/on condition assiociated with mechanical switches is therefor eliminated. I have a schematic in my archive I can share, when I get home, not a problem. Then, after making the switch bounceless, you use either a Flip-Flop circuit or four inverters to control the enable lines of the two eeproms, which you are correct, can only have the data set information changed, not the actual code. A friend of mine who designed embedded systems for a career, has such a system that actually allows CODE changes... this is because, the main loop of the program always starts at one particular address, on both chips, then the processor switches the enable pins on the EEprom, not a mechanical switch. The mechanical switch controls one of the inputs on the processor, when when it hits the beginning of the loop, where the code is the same in both chips, will enable or disable the appropriate eeprom. Just some thoughts :) Frederic Breitwieser Homebrew Automotive Mailing List Bridgeport, CT 06606 http://www.geocities.com/MotorCity/Downs/4605/index.html 1989 AG Hummer 4-Door 1993 Supercharged Lincoln Continental 2000 Mid-Engine Sports Car - --- ------------------------------ From: Frederic Breitwieser Date: Mon, 21 Jul 1997 14:59:01 -0400 Subject: Re: eproms via lpt >Has anyone had a go at rippin out the eprom from a memcal and replacing >it with a eeprom and interfacing it with the lpt of a pc??? maybe edit >a bin file then just plugin and send it on down rather than erasing the >eprom ......rather than removing the memcal at all???? Yes Justin, I see exactly what you are getting at. I had ordered a while back a LPT-based eeprom programmer, however it was mis-delivered and eventually out of fustration I cancelled the order. If you are running a GM based V8 ECM, there are some shareware/freeware programs on the internet that allows you to tweek the settings, however I have not tested this or played with it. All GM, late model Ford, and some of the foreign vehicles have some kind of interface installed... however one needs to create an interface between the proprietary ECM interface and the PC to grab and manipulate the data. In the Buick Grand National world, "TurboLink" comes to mind, and is an excellent product. I checked out the demo version, and the screens offers a lot of information. Hope that helped. Frederic Breitwieser Homebrew Automotive Mailing List Bridgeport, CT 06606 http://www.geocities.com/MotorCity/Downs/4605/index.html 1989 AG Hummer 4-Door 1993 Supercharged Lincoln Continental 2000 Mid-Engine Sports Car - --- ------------------------------ From: muwtj1@xxx.edu (Bill Jenkins) Date: Mon, 21 Jul 1997 13:45:14 -0700 (PDT) Subject: Re: eproms via lpt > >If you are running a GM based V8 ECM, there are some shareware/freeware >programs on the internet that allows you to tweek the settings, however I >have not tested this or played with it. > >In the Buick Grand National world, "TurboLink" comes to mind, and is an >excellent product. I checked out the demo version, and the screens offers >a lot of information. > >Frederic Breitwieser >Homebrew Automotive Mailing List >Bridgeport, CT 06606 >http://www.geocities.com/MotorCity/Downs/4605/index.html >1989 AG Hummer 4-Door >1993 Supercharged Lincoln Continental >2000 Mid-Engine Sports Car > > > Where might I get the demo versions of these products? I would like to play with them a bit. Bill Jenkins muwtj1@xxx.edu http://www.wiu.edu/users/muwtj1 The Chevrolet Beretta Home Page ------------------------------ From: Clare Snyder Date: Mon, 21 Jul 1997 19:30:52 -0400 Subject: analog or KISS EFI Anyone out there have any experience with a simple, low cost, reliable injection system foe nominal 100hp 4 cyl 4 stroke? KISS for Keep It Simple S- well - you know!! ------------------------------ From: muwtj1@xxx.edu (Bill Jenkins) Date: Mon, 21 Jul 1997 17:14:25 -0700 (PDT) Subject: Best? I have a test engine that I'd like to assemble an EFI system for, preferably PFI. It is a Chevrolet V-8, currently on a test stand. I'd like to know people's opinions on the best system (among those available on the internet) that I could hope to assemble by myself. Yes, I can drag my computer to the garage if necessary (to hook up serial ports or whatever). It doesn't have to be fully functional as in cold-start performance, but I'd just like to play around with one. Bill Jenkins muwtj1@xxx.edu http://www.wiu.edu/users/muwtj1 The Chevrolet Beretta Home Page ------------------------------ From: Sandy Date: Mon, 21 Jul 1997 17:21:57 -0700 Subject: Re: analog or KISS EFI At 07:30 PM 7/21/97 -0400, you wrote: >Anyone out there have any experience with a simple, low cost, reliable >injection system foe nominal 100hp 4 cyl 4 stroke? KISS for Keep It >Simple S- well - you know!! > You could scavange one off old BMW's, VW's they have the Bosch mechanical, but I'm not sure how to tune these. Not much electronics, but a slew of odd mechanical things. I have such a system on a BMW 6 cyl, and it works pretty well (most of the time!). Sandy ------------------------------ From: "Steve Meade" Date: Mon, 21 Jul 1997 18:28:58 -0700 Subject: Re: analog or KISS EFI - ---------- > From: Sandy > To: diy_efi@xxx.edu > Subject: Re: analog or KISS EFI > Date: Monday, July 21, 1997 5:21 PM > > At 07:30 PM 7/21/97 -0400, you wrote: > >Anyone out there have any experience with a simple, low cost, reliable > >injection system foe nominal 100hp 4 cyl 4 stroke? KISS for Keep It > >Simple S- well - you know!! > > > > You could scavange one off old BMW's, VW's they have the Bosch mechanical, > but I'm not sure how to tune these. Not much electronics, but a slew of odd > mechanical things. I have such a system on a BMW 6 cyl, and it works pretty > well (most of the time!). > That's a good idea. There are a lot of 318i ('84 and '85) cars in j-yards with L-Jetronic injection systems. They put out about 100HP. Sandy, why didn't you just upgrade to a lter Motronic system for your 6-cyl BMW? The Motronic system works the best and can be easily chipped. > Sandy =-=-=-=-=-=-=-=-=-=-= Steve Meade smeade@xxx.com ------------------------------ From: Simon Quested Date: Tue, 22 Jul 1997 14:11:33 +1200 Subject: Re: analog or KISS EFI Hi I'm running a 9 year old 2nd hand analog efi unit. it has 7 wires to run everything and a pressure line to a map sensor. It has 7 pot's to set the on time for the injectors over the rev range (as long as you don't want to rev higher than 7000rpm) and another pot that does the job of the acclerator pump. Very simple. Here in NZ the only way you can get one of these is 2nd hand. It works fine but I'm saving my dollars for a Link as it controls fuel/ignition/revs and the boost solenoid (I left the spec sheet at home I'll bring it in tomorrow) Cheers Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested (E-mail questeds@xxx.nz) Computer Technician, Silicon Graphics & Windows NT Support Centre for Computing and Biometrics LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ http://www.lincoln.ac.nz/ccb/techs/simon/default.htm +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ If voting could really change things, it would be illegal. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ From: Sandy Date: Mon, 21 Jul 1997 19:13:05 -0700 Subject: Re: analog or KISS EFI > Sandy, why didn't you just upgrade to a lter Motronic system for your >6-cyl BMW? The Motronic system works the best and can be easily chipped. Why tamper with something that works, I'm pretty lazy and the mech injection is working pretty well. Not something that I haven't thought about, even just getting a 325i engine with the whole deal... Sandy ------------------------------ From: Simon Quested Date: Tue, 22 Jul 1997 14:21:34 +1200 Subject: Re: analog or KISS EFI Hi All > You could scavange one off old BMW's, VW's they have the Bosch mechanical, > but I'm not sure how to tune these. Not much electronics, but a slew of odd > mechanical things. I have such a system on a BMW 6 cyl, and it works pretty > well (most of the time!). Have a look at : http://www.students.tut.fi/~hezekiel/bosch.htm It explans Bosh k jetronic Hessu has used this system on his 1600cc 4cyl and now it's on a 2.8 liter V6 Cheers Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested (E-mail questeds@xxx.nz) Computer Technician, Silicon Graphics & Windows NT Support Centre for Computing and Biometrics LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ http://www.lincoln.ac.nz/ccb/techs/simon/default.htm +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ If voting could really change things, it would be illegal. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ From: James Boughton Date: Mon, 21 Jul 1997 22:43:14 -0400 Subject: RE: Throttle body sizing Bruno, To determine the proper size for an intake system you need to know what rpm you intend to run to. Typically the intake system is sized to create a theoretical flow velocity of ~60m/s. Not perfect, but a good starting point. I would use the area of the throttle body throats minus the area taken up by the throttle shaft (probably ~10mm dia.) So if you are using a 40mm t/b you should have 1257mm^2 area. If you remove the area of a 10mm shaft you should be left with approx. 860mm^2. Next, take your cylinder displacement of 500cc/cyl and the rpm (I'll use 6000rpm) and calculate the airflow rate for an intake event. This should be 6000rpm x 500cc x 2 / (60sec/min) = 100000 cc/sec divide 100000cc/s by 8.6cm^2 and you get ~116m/s. This would be a little high which would likely cause power to drop off early. If you want to run a lower peak power speed then you would have to recalculate accordingly. By the way, the mysterious 2 in the equation is because the intake event only gets a half of a rev to occur. Also, the value of the area used should be the average intake area and can be made higher by using trumpets (air horns, stacks, whatever!) that have a large taper. All of this also depends on cams, port flow coefficients, and so on. When you get to the point of tuning for length let me know :-) Jim Boughton boughton@xxx.net - ---------- From: Bruno![SMTP:b.marzano@xxx.au] Sent: Monday, July 21, 1997 10:52 AM To: diy_efi@xxx.edu Subject: Throttle body sizing Hi everyone, I have a 2lt twin cam and am considering rigging up a quad throttle efi manifold for it. Firstly, I will be using the throttle bodies from stromberg carburettors to save the pain of trying to fabricate a tb from scratch. I can get these in sizes up to 40mm (i think 1 9/16") at a reasonable price. The intake runners which will mount on the head, and hold the tbs, will be made using aluminium tube, the internal diameter of which i can get in different sizes quite readily. again, i could get this in 40mm, or slightly smaller, or even larger (i think 50mm od & 3mm wall gives 44mm). The 44 mm option would be a little silly, as the tb being 40mm would be a restriction (compared to the runner). My question is whether 40mm is too large for this type of engine. It currently gives about 130hp, and is my mild-mannered street car. Driveability is my main criterion here. Any ideas would be greatly appreciated. Bruno. (b.marzano@xxx.au) Early to bed, Early to rise Makes a man or woman miss out on the night life -Morphine begin 600 WINMAIL.DAT M>)\^(C$"`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$-@ 0` M`@````(``@`!!) &`&0!```!````# ````,``# #````"P`/#@`````"`?\/ M`0```&,`````````@2L?I+ZC$!F=;@#=`0]4`@````!D:7E?969I0&-O=6QO M;6(N96YG+F]H:6\M``,P`0`` M`",```!D:7E?969I0&-O=6QO;6(N96YG+F]H:6\M5]E9FE 8V]U;&]M8BYE;FL"@P!0 M`O()`@!C: K M<@xxx.@W'5P*3 C)"TG L M8BLR,W06$ 1@xxx. >$' =(7CM M(G X)_$VT2X*A1M:!\ >>"D1'G,?,07 8WELUPN !($RL7,+46,3X GP`P5 M)[$U,#!C8R\_/P$>$1^A'/$@\0J%*$G^)R,`*],G\$"@(/$S`$$RW2+A8RN@ M);(L(VDHT";B-G(ELAWL92<@xxx.J<\WQOP0O4@>/= A$G1$> O M,; G\!&P0-#[')$S`#TYD4NR)7! T$KQ\T@\,L!V:0VP2Y5,$C!2<#@N-F,V MTR&Q'S)G\Q' ,E$Q-B@xxx.[ @H/\BT%*!*Y,_ M(!Z0(Q$BX"OB[2K@xxx.R!4 M0QU0'H!4)3^P'X/_'/ #H%8#->@AX@600]<`T-\%H3+ &1!5@0J%0B,D5D#V M>3Y!'/%M$[(%$ A@!"#'$> +@!S397%U(,!=L+\>,4Y16G$KYD7J)Z!N(Q#? M"H5/H00@)? 1@&PGP#E37180=B'2)U!#\'(\S4'L;',;,!S3=@= "E LIO\L M8ROA'Z ZF"PC)R!%($^@xxx.P`*A0# 39&O4E(=83!A-'1T&P!M M'5#]+E$H1*$V( 6P`( I("I1G&-K; $@HD91Z%G2#T+ M`S\@,30T\ (`:?XM?7,,T'US"UE0``J@+4'Y*/$@+8 7"H=^RPPP?Y9Z1@-A M.H$>?Y8;PQKS(0!;4TU44#IB+DD`P')Z`'!O0!/ =:\-L"L1:,$[`')%("X) M@/1U+E/@78"_@!!38>_@(G<")P1D2P$\ C$"D@_RMA`Q #(#L!:H4L_0B0!""_`U(I MYP-AAN$JP"+@\LHYQ@:J,<(&8!H 40(N#_ M)<0;\*9J!0`@P!%P(G K8/]HPG6#'/ K\5XA'9($(# QVR'A-/,HG!!PH6Y8 M$!K0]#DO4 `B0V$I89G5)9']9'!N,A$=`B+0DX!(+4;0_R-G&P$ '&$GHE*DG!"LM@xxx.?_#= $D$ BK<1>H"=P09&U8?\# M$%619X +<2D@NU$KDZST_R1A7B$T\BD@!; IYC\@>B'](Q%S`, C``20P&)& M0VXD'T(QKN9 D#*1!' @)B#^,S*15D!"@:!@)R $('V _3*0*3S&LJ)]@"YP MP^$%,/]>XE#?'8$C`7.Q+L.K$CL`?RJB-//'*+ WIQ$BT%[3*/\%H&L0+&$A MPT%SLV/%@$@M_DTC(%Z@RR%>Y2"@$ _QU0 M)Z)W@1RAK'$%0)G58S$_O-(C$<3D`: (8 5 ,3/X,&AP<[0D85U0+G$KL/XM M`X&S@xxx.@:A&3@&-] M;O_800VPR+'')PG!(, C$3O2]P60!S 3T&0\SQOAA(@B<-XHA9^&KGC-&\-% M56(ATK\[`+6!XJ<%$!&P&UI-'H'_8<(#@@6Q*X #@AR0!!'4,O^TY0,`>B%1 M<2C@W<_HSQOA_BV+T"#PKQ$O!IEO"R@2LB\,`W^6Z\45,0#NP ````,`$! ` M`````P`1$ ````! ``C^6O % ``@xxx.%F>C^6O $>`#T``0````4` ,``!213H@`````%1/ ` end ------------------------------ From: clsnyde@xxx.net (Clare Snyder) Date: Tue, 22 Jul 1997 03:42:21 GMT Subject: Re: analog or KISS EFI >Hi > >I'm running a 9 year old 2nd hand analog efi unit. it has 7 wires to >run everything and a pressure line to a map sensor. It has 7 pot's to >set the on time for the injectors over the rev range (as long as you >don't want to rev higher than 7000rpm) and another pot that does the >job of the acclerator pump. Very simple. Here in NZ the only way you >can get one of these is 2nd hand. >It works fine but I'm saving my dollars for a Link as it controls >fuel/ignition/revs and the boost solenoid (I left the spec sheet at >home I'll bring it in tomorrow) > >Cheers > >Simon > >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Simon Quested (E-mail questeds@xxx.nz) > Computer Technician, Silicon Graphics & Windows NT Support > Centre for Computing and Biometrics > LINCOLN UNIVERSITY OF NEW ZEALAND > Phone (64)(03) 3252811 Ext. 8087 >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >http://www.lincoln.ac.nz/ccb/techs/simon/default.htm >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >If voting could really change things, it would be illegal. >+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > what kind of analog system is it? Made by who? Any schematics available? etc etc. ------------------------------ From: pantera@xxx.com (David Doddek) Date: Mon, 21 Jul 1997 23:37:49 -0500 (CDT) Subject: Re: analog or KISS EFI >Anyone out there have any experience with a simple, low cost, reliable >injection system foe nominal 100hp 4 cyl 4 stroke? KISS for Keep It >Simple S- well - you know!! > > Yea, I built one. When it is ready for full production, I will announce it to the list as promised earlier this summer. David Doddek pantera@xxx.com/~pantera 217-422-3722 69 EFI Fairlane, 89 T-bird SC, 74 Twin turbo NOS EFI Pantera #6825 If you are going to go fast, go real fast. ------------------------------ From: "Allan Hines" Date: Tue, 22 Jul 1997 15:51:03 +1000 Subject: Re: Throttle body sizing James Boughton wrote : > Next, take your cylinder displacement of 500cc/cyl and the rpm > (I'll use 6000rpm) and calculate the airflow rate for an intake event. This > should be > > 6000rpm x 500cc x 2 / (60sec/min) = 100000 cc/sec The above formula is incorrect Assuming 100% volumetric efficiency (6000rpm x 500cc) / ( 2 x 60 ) = 25,000 cc/sec = 25 Litre/sec Allan Hines - ---------- > From: James Boughton > To: 'diy_efi@xxx.edu' > Subject: RE: Throttle body sizing > Date: Tuesday, 22 July 1997 12:43 PM > > Bruno, > To determine the proper size for an intake system you need to > know what rpm you intend to run to. Typically the intake system is sized > to create a theoretical flow velocity of ~60m/s. Not perfect, but a good > starting point. I would use the area of the throttle body throats minus the > area taken up by the throttle shaft (probably ~10mm dia.) So if you are > using a 40mm t/b you should have 1257mm^2 area. If you remove the area > of a 10mm shaft you should be left with approx. 860mm^2. > > Next, take your cylinder displacement of 500cc/cyl and the rpm > (I'll use 6000rpm) and calculate the airflow rate for an intake event. This > should be > > 6000rpm x 500cc x 2 / (60sec/min) = 100000 cc/sec > > divide 100000cc/s by 8.6cm^2 and you get ~116m/s. This would be a little > high which would likely cause power to drop off early. If you want to run > a lower peak power speed then you would have to recalculate accordingly. > By the way, the mysterious 2 in the equation is because the intake event only > gets a half of a rev to occur. > > Also, the value of the area used should be the average intake area and can be > made higher by using trumpets (air horns, stacks, whatever!) that have a large > taper. > > All of this also depends on cams, port flow coefficients, and so on. When you > get to the point of tuning for length let me know :-) > > Jim Boughton > boughton@xxx.net > > ---------- > From: Bruno![SMTP:b.marzano@xxx.au] > Sent: Monday, July 21, 1997 10:52 AM > To: diy_efi@xxx.edu > Subject: Throttle body sizing > > Hi everyone, > > I have a 2lt twin cam and am considering rigging up a quad throttle efi > manifold for it. Firstly, I will be using the throttle bodies from > stromberg carburettors to save the pain of trying to fabricate a tb from > scratch. I can get these in sizes up to 40mm (i think 1 9/16") at a > reasonable price. > > The intake runners which will mount on the head, and hold the tbs, will be > made using aluminium tube, the internal diameter of which i can get in > different sizes quite readily. again, i could get this in 40mm, or > slightly smaller, or even larger (i think 50mm od & 3mm wall gives 44mm). > The 44 mm option would be a little silly, as the tb being 40mm would be a > restriction (compared to the runner). > > My question is whether 40mm is too large for this type of engine. It > currently gives about 130hp, and is my mild-mannered street car. > Driveability is my main criterion here. > > Any ideas would be greatly appreciated. > > Bruno. (b.marzano@xxx.au) > > Early to bed, Early to rise > Makes a man or woman miss out on the night life > -Morphine > > > ------------------------------ From: Simon Quested Date: Tue, 22 Jul 1997 18:28:43 +1200 Subject: Re: analog or KISS EFI Hi All > what kind of analog system is it? Old is about all I can tell you > Made by who? Auto Logic Systems > Any schematics available? etc Not that I have been able to find...but I haven't looked very hard as the is just a "get me by" untill I can afford better. Sorry I can't be of more help Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested (E-mail questeds@xxx.nz) Computer Technician, Silicon Graphics & Windows NT Support Centre for Computing and Biometrics LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ http://www.lincoln.ac.nz/ccb/techs/simon/default.htm +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ f u cn rd ths, u cn gt a gd jb n cmptr prgmmng +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ End of DIY_EFI Digest V2 #246 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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