DIY_EFI Digest Wednesday, 5 June 1996 Volume 01 : Number 157 In this issue: Re: MAF vs MAP Re: MAF vs MAP Re: re: Re: MAF vs MAP Re: Re: Re: MAF vs MAP Re: MAF vs MAP re: Re: MAF vs MAP Re: How about no MAF or MAP? Re: Re: Re: Forced induction/supercharger Re: Forced induction/supercharger, additional comment Re[2]: help Re: 20 more HP Re: MAF vs MAP Re: Re: Re: Forced induction on a 2.5 Liter 4 cylinder. Re: MAF vs MAP Re: How about no MAF or MAP? Re: Forced induction on a 2.5 Liter 4 cylinder. re: Re: Forced induction on a 2.5 Liter 4 cylinder. See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: atsakiri@xxx.com Date: Wed, 05 Jun 96 08:25:53 -0400 Subject: Re: MAF vs MAP > Correct me if I'm wrong, but both GM and Ford "MAF" systems still run a MAP > sensor to deal with situations that the MAF can't handle (transients, I > presume). Current Ford "MAF" (mass air flow) systems do not include MAP (manifold absolute pressure) sensors. Cost is a big issue. I'd be interested in anyone's experiences using both MAF and MAP sensors on a single engine. Anthony Tsakiris ------------------------------ From: atsakiri@xxx.com Date: Wed, 05 Jun 96 08:43:26 -0400 Subject: Re: MAF vs MAP > MAF sensors can handle all the transients you can throw at them > provided they're set up properly, ie, they're sampled correctly and > you have some form of manifold filling compensation. I suspect that > the additional MAP sensor is for added functionality, perhaps EGR > control or maybe something else. "sampled correctly and you have some form of manifold filling compensation" -- here, here! Thanks for including that short yet very important statement. Ford currently uses a separate delta pressure gauge, dedicated to the EGR system, to estimate EGR flow rate. Speaking of EGR, it highlights a disadvantage of a MAP-based system for determining inducted air. A MAP sensor measures the pressure of the gas in the intake manifold. Unfortunately, that's not the same thing as the partial pressure of the air in the manifold under all conditions. So, in addition to compensation for volumetric efficiency, the ideal gas law estimate must be adjusted for EGR. Anthony Tsakiris Abbreviations: EGR = exhaust gas recirculation MAP = manifold absolute pressure - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: "Josh Karnes" Date: Wed, 5 Jun 1996 09:17:33 +0000 Subject: Re: > I'm trying to asses the potential for a forced induction system to > get about 20 more HP out of the 4 cyl engine..... Say what? There is no way to get 20 more hp from a 4 cyl engine (the 2.5L injected "slant-four" from Chrysler, right?) with induction mods unless you add a turbo. You *might* get as much as 3-5 hp at high speeds if you manage to design a very good forced system, but that will really only have an effect at speeds of 50+ mph. You can get a couple more ponies just by making a better, higher-flowing airbox, or cooling the air coming in (or keeping it cool, once it is cool), but the forced-air idea is not going to yield that kind of power increase. I hope you were kidding :) _____________________________________________________________________________ Josh Karnes joshk@xxx.com Renaissance Man http://www.tanisys.com/~joshk/home.htm Tanisys Technology http://www.tanisys.com Austin, Texas '78 BMW 530i | '72 Datsun 240Z | IZCC #308 _____________________________________________________________________________ *** opinions expressed herein are MINE, ALL MINE!! *** ------------------------------ From: SRavet@xxx.com Date: Wed, 5 Jun 96 9:25:06 CDT Subject: re: Re: MAF vs MAP atsakiri@xxx.com Wrote: | | | > MAF sensors can handle all the transients you can throw at them | > provided they're set up properly, ie, they're sampled correctly and | > you have some form of manifold filling compensation. I suspect that | > the additional MAP sensor is for added functionality, perhaps EGR | > control or maybe something else. Seems like the MAP sensor could be used to measure the transients in the manifold. Then maybe you wouldn't need to use throttle delta to calculate the acceleration enrichment. - --steve Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: atsakiri@xxx.com Date: Wed, 05 Jun 96 10:39:11 -0400 Subject: Re: > > I'm trying to asses the potential for a forced induction system to > > get about 20 more HP out of the 4 cyl engine..... > > Say what? There is no way to get 20 more hp from a 4 cyl engine (the > 2.5L injected "slant-four" from Chrysler, right?) with induction mods > unless you add a turbo. You *might* get as much as 3-5 hp at high > speeds if you manage to design a very good forced system, but that > will really only have an effect at speeds of 50+ mph. You can get a > couple more ponies just by making a better, higher-flowing airbox, or > cooling the air coming in (or keeping it cool, once it is cool), but > the forced-air idea is not going to yield that kind of power > increase. I'm confused. What's the definition of "forced induction?" I took it to mean mechanically supercharged or turbocharged. Anthony Tsakiris - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Wed, 5 Jun 1996 11:08:44 +0500 Subject: Re: > I'm trying to asses the potential for a forced induction system to > get about 20 more HP out of the 4 cyl engine..... >Say what? There is no way to get 20 more hp from a 4 cyl engine (th >2.5L injected "slant-four" from Chrysler, right?) with induction mods >unless you add a turbo...I hope you are kidding. I hope YOU are kidding. The guy says he wants to add a forced induc- tion system, which a turbo is. Yes, you can get that kind of power out of a 4 banger, especially a weak one. In rough terms, if he can achieve 0.5 atm of boost at 5000rpm, and assuming horrendous losses costing him half of that, he will get nearly 25% more torque than he is in N/A form. If the Chrysler makes 80hp @ 5000rpm in N/A form(and we know it makes much more than that), he will have his additional 20hp. His goal is easily achievable. Ed Hernandez Ford Motor Company ehernan3@xxx.com ------------------------------ From: atsakiri@xxx.com Date: Wed, 05 Jun 96 11:16:25 -0400 Subject: Re: MAF vs MAP > atsakiri@xxx.com Wrote: > | > | > | > MAF sensors can handle all the transients you can throw at them > | > provided they're set up properly, ie, they're sampled correctly and > | > you have some form of manifold filling compensation. I suspect that > | > the additional MAP sensor is for added functionality, perhaps EGR > | > control or maybe something else. I responded to this, but I didn't write it. (Technicality.) > Seems like the MAP sensor could be used to measure the transients in the > manifold. Then maybe you wouldn't need to use throttle delta to calculate > the acceleration enrichment. Yes, one would think that. I'm sure it can, but I've never come across a specific, complete plan detailing how to do it. That's not to say one doesn't exist. Decisions need to be made regarding under what condition to use which sensor, how to switch modes, etc. It gets cumbersome (computationally, in the production world) quickly. As for acceleration enrichment, we've entered a new arena. Now we're discussing A/F ratio control, not measurement of inducted air. If the approach is to add additional fuel, without trying to measure air then calculate the amount of fuel (based on measured air and desired A/F ratio), then why add a MAP sensor? The throttle position sensor is already there. Am I missing a benefit of MAP-based enrichment over throttle-based enrichment? Anthony Tsakiris A/F = air-fuel MAP = manifold absolute pressure (Should I still be adding these definitions. I recall a past discussion.) - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: Gary W Harris Date: Wed, 05 Jun 96 08:18:00 PDT Subject: Re: MAF vs MAP Text item: > MAF sensors can handle all the transients you can throw at them > provided they're set up properly, ie, they're sampled correctly and > you have some form of manifold filling compensation. I suspect that > the additional MAP sensor is for added functionality, perhaps EGR > control or maybe something else. "sampled correctly and you have some form of manifold filling compensation" -- here, here! Thanks for including that short yet very important statement. Ford currently uses a separate delta pressure gauge, dedicated to the EGR system, to estimate EGR flow rate. Speaking of EGR, it highlights a disadvantage of a MAP-based system for determining inducted air. A MAP sensor measures the pressure of the gas in the intake manifold. Unfortunately, that's not the same thing as the partial pressure of the air in the manifold under all conditions. So, in addition to compensation for volumetric efficiency, the ideal gas law estimate must be adjusted for EGR. - --In fact, there are extensive look-up tables in the GM ECU's to compensate for the flow and mixture dilution due to EGR. All must be accounted for... GH Anthony Tsakiris Abbreviations: EGR = exhaust gas recirculation MAP = manifold absolute pressure - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. Text item: External Message Header The following mail header is for administrative use and may be ignored unless there are problems. ***IF THERE ARE PROBLEMS SAVE THESE HEADERS***. Reply-To: diy_efi@xxx.edu Precedence: bulk Sender: owner-diy_efi@xxx.edu X-Mts: smtp Date: Wed, 05 Jun 96 08:43:26 -0400 In-Reply-To: Your message of "Wed, 05 Jun 96 13:44:08 EST." <9606051744.AA00027@xxx.au> Subject: Re: MAF vs MAP To: diy_efi@xxx.edu Received: by internet-mail2.ford.com (Protected-side Proxy Mail Agent-1); Wed, 5 Jun 1996 08:43:27 -0400 Received: by internet-mail2.ford.com (Protected-side Proxy Mail Agent-2); Wed, 5 Jun 1996 08:43:27 -0400 Message-Id: <199606051243.AA16394@xxx.com> Received: by internet-mail2.ford.com id AA16394 (InterLock SMTP Gateway 3.0 for diy_efi@xxx.edu); Wed, 5 Jun 1996 08:43:27 -0400 From: atsakiri@xxx.com Received: from internet-mail2.ford.com by coulomb.eng.ohio-state.edu via SMTP (9 40816.SGI.8.6.9/940406.SGI) for id IAA13563; Wed, 5 Jun 1996 08:43 :52 -0400 Received: by coulomb.eng.ohio-state.edu (940816.SGI.8.6.9/940406.SGI) id MAA13568; Wed, 5 Jun 1996 12:43:53 GMT Received: from coulomb.eng.ohio-state.edu (coulomb.eng.ohio-state.edu [128.146.9 0.150]) by ormail.intel.com (8.7.4/8.7.3) with SMTP id HAA15147 for ; Wed, 5 Jun 1996 07:31:24 -0700 (PDT) Received: from ormail.intel.com (ormail.intel.com [134.134.248.3]) by relay.jf.i ntel.com (8.7.4/8.7.3) with ESMTP id HAA18078 for ; Wed, 5 Jun 1996 07:31:26 -0700 (PDT) Return-Path: owner-diy_efi-outgoing@xxx.edu ------------------------------ From: SRavet@xxx.com Date: Wed, 5 Jun 96 10:49:52 CDT Subject: re: Re: MAF vs MAP atsakiri@xxx.com Wrote: | I responded to this, but I didn't write it. (Technicality.) oops | | |>Seems like the MAP sensor could be used to measure the transients in the |>manifold. Then maybe you wouldn't need to use throttle delta to calculate |>the acceleration enrichment. | | Yes, one would think that. I'm sure it can, but I've never come | across a specific, complete plan detailing how to do it. That's | not to say one doesn't exist. Decisions need to be made regarding | under what condition to use which sensor, how to switch modes, | etc. It gets cumbersome (computationally, in the production | world) quickly. I'm not talking about switching modes, I'm talking about using both sensors as inputs to a control equation. Throttle openings and closings can cause transients in the manifold/plenum that the MAF sensor won't see, right? There was a discussion a long time ago about equations to model these transients in order to correct the MAF measurement. It seems like using a MAP sensor to measure transients would be easier than constructing a mathematical model of the intake. Isn't the throttle based enrichment algorithm a simple way of approximating this transient condition? | | As for acceleration enrichment, we've entered a new arena. Now | we're discussing A/F ratio control, not measurement of inducted | air. If the approach is to add additional fuel, without trying | to measure air then calculate the amount of fuel (based on | measured air and desired A/F ratio), then why add a MAP sensor? | The throttle position sensor is already there. Am I missing a | benefit of MAP-based enrichment over throttle-based enrichment? No, I am probably missing it. You are right, the throttle sensor is there, might as well use it. I was curious about a MAP sensor in this application | A/F = air-fuel | MAP = manifold absolute pressure (Should I still be adding these | definitions. I recall a past | discussion.) might as well.... I remember being pretty lost right after I first subscribed. Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: "Josh Karnes" Date: Wed, 5 Jun 1996 11:23:06 +0000 Subject: Re: How about no MAF or MAP? > My pet project at the moment, is a EFI (& Elec. Ign.) system for my > Datsun 510 club race car. I've taken one look at your average flap > type mass airflow sensor (280ZX) L-Jet. OK, I wanna get into this discussion, as I have a BMW with an L-Jet that I'd love to modify. Of course, this car has the complete L-Jet on there now, with all the sensors and AFM, TPS, etc. Also, the original throttle body. I don't have to meet any emmissions tailpipe tests or whatever here in Austin either, so I am very much interested in ditching the AFM in my car. I assume that after a certain number of rpms, the ECU takes over for the miixture curve. It has to sense this rpm somewhere, right? Which means that there must be some circuitry in there for determining injector pulse width based on rpm. This must also be independent of the throttle position. Is it feasible that you could feed the AFM inputs on the ECU with the output of some circuit comprising of a frequency-to-voltage converter and some op amps, so you could simulate a condition of the variable resistor AFM? Basically a voltage is applied to the rail of the AFM, then there is some resistance, so there is an output voltage after the drop through the resistor (there must be a reference resistor in the ECU, I guess). So, with a frequency-to-voltage converter sampling pulses from the coil, you can convert the rpms to a voltage. You can then use some sort of variable resistor to find the throttle position. Use these to drive the input of an op amp that can be tuned to give a voltage output approximating that of the AFM in the same scenario. This would adjust the pulse width of the injectors based both on throttle position and on rpm. No restriction from the AFM either. Just a thought. I am sure you guys have been all over mmodifying L-Jet EFI, so is there an archive anywhere I can read? I'd like to get up to speed on the state of the discussion before asking a bunch of questions that have been answered a million times or bringing up topics that have been covered already. Later- _____________________________________________________________________________ Josh Karnes joshk@xxx.com Renaissance Man http://www.tanisys.com/~joshk/home.htm Tanisys Technology http://www.tanisys.com Austin, Texas '78 BMW 530i | '72 Datsun 240Z | IZCC #308 _____________________________________________________________________________ *** opinions expressed herein are MINE, ALL MINE!! *** ------------------------------ From: "David W. Taylor" Date: Wed, 05 Jun 1996 09:28:13 -0700 Subject: Re: Josh Karnes wrote: > > > I'm trying to asses the potential for a forced induction system to > > get about 20 more HP out of the 4 cyl engine..... > > Say what? There is no way to get 20 more hp from a 4 cyl engine (the > 2.5L injected "slant-four" from Chrysler, right?) with induction mods > unless you add a turbo. You *might* get as much as 3-5 hp at high > speeds if you manage to design a very good forced system, but that > will really only have an effect at speeds of 50+ mph. You can get a > couple more ponies just by making a better, higher-flowing airbox, or > cooling the air coming in (or keeping it cool, once it is cool), but > the forced-air idea is not going to yield that kind of power > increase. > > I hope you were kidding :) Actually I am considering a small Roots (Whipple Charger) Blower. When I used the term forced I meant it :) Upgrading to forged pistons, And if the $$ work out Mopar Performance Aluminum High Flow Head. Like I say, this is the research stage, I get about 120 Hp now and Set an arbitrary target of 140 as a design goal. The trick is I want to do a bypassed turbo or Super charger with a demand clutch to shift it in and out of the system. I'm leaning toward the mechanical blower because in my 4x4 throttle response is an issue. Mopar has a complete performance kit for the motor that bumps it to about 160 HP but its MAJOR $$ ,, Around 5K. And its all High rev power. Heck if ya don't check out all your options how are you going to empty your wallet. My checking account seems to have the ability to go from full to emty in < .4 seconds.... :) - -- David Taylor dwtaylor@xxx. My opinions are mine ,, and nobody elses. ------------------------------ From: Frank Parker Date: Wed, 5 Jun 1996 12:59:02 -0600 (EDT) Subject: Re: > > > I'm trying to asses the potential for a forced induction system to > > get about 20 more HP out of the 4 cyl engine..... > > >Say what? There is no way to get 20 more hp from a 4 cyl engine (th > >2.5L injected "slant-four" from Chrysler, right?) with induction mods > >unless you add a turbo...I hope you are kidding. > > I hope YOU are kidding. The guy says he wants to add a forced induc- > tion system, which a turbo is. Yes, you can get that kind of power out > of a 4 banger, especially a weak one. In rough terms, if he can > achieve 0.5 atm of boost at 5000rpm, and assuming horrendous losses > costing him half of that, he will get nearly 25% more torque than he > is in N/A form. If the Chrysler makes 80hp @ 5000rpm in N/A form(and > we know it makes much more than that), he will have his additional > 20hp. His goal is easily achievable. > I do not believe he knows what he is asking. I have done several turbo and they are not for the inexperienced. He should have a very mild NO2 fogger added. Cheap and if installed correctly, @xxx. frank parker ------------------------------ From: atsakiri@xxx.com Date: Wed, 05 Jun 96 13:12:31 -0400 Subject: Re: Forced induction/supercharger > Actually I am considering a small Roots (Whipple Charger) Blower. > When I used the term forced I meant it :) > [snip] > > I get about 120 Hp now and Set an arbitrary target of 140 as a design > goal. The trick is I want to do a bypassed turbo or Super charger > with a demand clutch to shift it in and out of the system. I'm leaning > toward the mechanical blower because in my 4x4 throttle response is an > issue. [snip] You can also "bypass" a mechanical supercharger. The 1.5 liter Roots blower on the supercharged 3.8 liter Ford V-6 recirculated the air from the supercharger outlet (after the intercooler actually) back to the supercharger's inlet. Air is still pumped around the loop, but against a very low pressure differential. When boost was desired, the recirculation path was closed. Air then flowed only to the intake manifold. The recirculation valve was a small throttle blade-like valve, moved by a vacuum actuator. It could also be operated based on throttle or pedal position. This approach might be less complicated and less expensive than a supercharger clutch. recirculation valve / +---------|X|--------------<---+ | | | ------- ------- | ---------- | | | | | | | | -->--+----| S/C |-->--| I/C |---+-->--| manifold |--> | | | | | | ------- ------- ---------- Anthony Tsakiris S/C = supercharger I/C = intercooler - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: atsakiri@xxx.com Date: Wed, 05 Jun 96 13:15:27 -0400 Subject: Re: Forced induction/supercharger, additional comment > > > I'm trying to asses the potential for a forced induction system to > > > get about 20 more HP out of the 4 cyl engine..... [snip] Frank Parker makes a good point about the about objective. The supercharger arrangement I previously described is a lot to go through for a small, 20 hp power increase. Anthony Tsakiris - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: jfaubion@xxx.mil (jfaubion) Date: Wed, 05 Jun 96 12:20:13 cdt Subject: Re[2]: >Say what? There is no way to get 20 more hp from a 4 cyl engine >(the 2.5L injected "slant-four" from Chrysler, right?) with >induction mods unless you add a turbo. Being a long time nitrous oxide racer, my first question would be for how long? If you only need the power for short bursts (say 5-20 seconds) at a time, use nitrous oxide injection. This should provide a reliable 20-30 hp. Especially if used in conjunction with a few pressure switches and a throttle position switch. This will allow you to use the nitrous at full throttle only and shut it down if oil or fuel pressure is lost. This works great for passing and merging with traffic. If you need the power for a longer period then I'd recommend turbocharging. Works great, lasts long time, and is a relatively easy DIY project. Is is just as dangerous to the life of the engine as nitrous but power can be used for longer periods. >speeds if you manage to design a very good forced system, but that >will really only have an effect at speeds of 50+ mph. You can get a >couple more ponies just by making a better, higher-flowing airbox, >or cooling the air coming in (or keeping it cool, once it is cool), >but the forced-air idea is not going to yield that kind of power Date: Wed, 5 Jun 1996 12:28:01 -0500 (EST) Subject: Re: 20 more HP > > > I'm trying to asses the potential for a forced induction system to > > > get about 20 more HP out of the 4 cyl engine..... > > > > I get about 120 Hp now and Set an arbitrary target of 140 as a design > goal. The trick is I want to do a bypassed turbo or Super charger > with a demand clutch to shift it in and out of the system. I'm leaning > toward the mechanical blower because in my 4x4 throttle response is an > issue. > > -- > David Taylor dwtaylor@xxx. > My opinions are mine ,, and nobody elses. > To use an Intel based analogy, you're attempting to emulate a Pentium using a '286. Wouldn't it be cheaper to stuff a V-6 or V-8 in place of the 4-cyl? Then you would have the bottom-end grunt you really need. - ---------------------------------------------------------------------------- Matthew D. Sale Delco Electronics Corp. All responses are my own and should not be mistaken for those of Delco Electronics or General Motors. ------------------------------ From: atsakiri@xxx.com Date: Wed, 05 Jun 96 13:37:38 -0400 Subject: Re: MAF vs MAP > |>Seems like the MAP sensor could be used to measure the transients in the > |>manifold. [snip] > | Decisions need to be made regarding > | under what condition to use which sensor, how to switch modes, > | etc. > I'm not talking about switching modes, I'm talking about using both sensors > as inputs to a control equation. Throttle openings and closings can cause > transients in the manifold/plenum that the MAF sensor won't see, right? > There was a discussion a long time ago about equations to model these > transients in order to correct the MAF measurement. It seems like using a > MAP sensor to measure transients would be easier than constructing a > mathematical model of the intake. Isn't the throttle based enrichment > algorithm a simple way of approximating this transient condition? I agree with you that a MAP sensor could possibly provide a benefit during transients. I just haven't figured out how to do it yet. :) If you've got the control equation, by all means DON'T send it to me! Send it to the list or some Ford lawyer. [ :) again ] If the MAF sensor is mounted upstream of the intake manifold, throttle position changes will produce air flow changes at the MAF sensor before pressure changes in the manifold. (Assumption: throttle flow is not choked.) The flow through the throttlebody and the MAF sensor will be a function of pressure ratio across the throttle and the flow area. Even if the pressure ratio doesn't change, the area surely will. The manifold pressure will lag the inflow. The flow rate at the throttle and MAF sensor will change dramatically. This air flow however (the flow INTO the manifold) is not that which is inducted into the cylinders. Some of that incoming air serves to raise the manifold pressure. After the transient event, inflow and outflow converge again. Anthony Tsakiris MAF = mass air flow MAP = manifold absolute pressure - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: "Josh Karnes" Date: Wed, 5 Jun 1996 12:49:54 +0000 Subject: Re: > > > I'm trying to asses the potential for a forced induction system to > > get about 20 more HP out of the 4 cyl engine..... > > >Say what? There is no way to get 20 more hp from a 4 cyl engine > >(th 2.5L injected "slant-four" from Chrysler, right?) with > >induction mods unless you add a turbo...I hope you are kidding. > > I hope YOU are kidding. The guy says he wants to add a forced induc- > tion system, which a turbo is. sorry, i thought he meant the 'ram-air' type jobbie whereby you simply reduct the intake air to get the air from the high-pressure area in front of the radiator. i misinterpreted 'forced-air', by which he meant turbocharger. sorry for the confusion. _____________________________________________________________________________ Josh Karnes joshk@xxx.com Renaissance Man http://www.tanisys.com/~joshk/home.htm Tanisys Technology http://www.tanisys.com Austin, Texas '78 BMW 530i | '72 Datsun 240Z | IZCC #308 _____________________________________________________________________________ *** opinions expressed herein are MINE, ALL MINE!! *** ------------------------------ From: Carter Hendricks Date: Wed, 5 Jun 1996 10:45:44 -0700 (PDT) Subject: Re: > > > I'm trying to asses the potential for a forced induction system to > > get about 20 more HP out of the 4 cyl engine..... > > >Say what? There is no way to get 20 more hp from a 4 cyl engine (th > >2.5L injected "slant-four" from Chrysler, right?) with induction mods > >unless you add a turbo...I hope you are kidding. > > I hope YOU are kidding. The guy says he wants to add a forced induc- > tion system, which a turbo is. Yes, you can get that kind of power out > of a 4 banger, especially a weak one. In rough terms, if he can A few of the earlier posts on this topic came to mind as I took a break from some Italian wiring problems and read through the only reason I subscribe to Cycle World: the monthly column [and occasional article] from Kevin Cameron. This month's TDC column is titled "Intake Flow 101." This list is often made more interesting by the wide range of experience of the participants. Kevin's articles are like that, too -- even on a topic where I feel fairly comfortable, his analysis always gives me a new idea or a new way of thinking about something. I think there was a little confusion about the meaning of forced induction among some of our participants here. And I think a few people were underestimating the amount of low speed help can [and on most modern cars finally does] come from the intake [and exhaust] system. I've been working on a couple of Alfa Romeo 1900 TI projects, and a few years ago was lucky enough to ask the right questions when interviewing a couple of the old-timer engineers. There was a lot of experimental testing going on in Milan in the very early 1950's. Kevin's column takes up the story about then... and follows with an interesting technical description. So if you have an extra $3.50 while at the grocery store... --Carter ------------------------------ From: "David W. Taylor" Date: Wed, 05 Jun 1996 12:41:39 -0700 Subject: Re: Forced induction on a 2.5 Liter 4 cylinder. Boy did a lot of people answer my question, :) Thanks. I got enough responses that I figured I'd better give you all a better description of the goal and the problem. I wish to take an engine equiped with MAP and Multi-Port fuel injection and increse the HP by 20+. Maintaining daily drivability, This is a 4x4 not a race car, so power control is VERY important. It would be a bad thing (tm) if I was crawling up a 45 degree rock face and when I gassed it to get over a small bump I got all 140 HP at once... Mission control we have liftoff. Un fortunately wranglers don't have a glide ratio. Turbo or Mechanical supercharger. At this point I am leaning towards using the Whipple Supercharger. The reason is that I want throttle response thats immediate, and I don't intend to run the engine at over 5K rpms. I've gotten a few sugestions ,, Here's my process of elimination, 1. Bigger motor - My only option in Oregon is the 4.0 6 Cyl. Our emissions laws don't allow the transplant of any motor into any vehicle that it did not come in as an option if the Chassis was manufactured after 1981. BUMMER> And the 4.0 6 cylinder gets in the low teens for mileage on a good day. 2. NO2 - I've seen some neat systems but I can't buy NO2 at Texaco. I'm unsure of "how much" of a nitrous system I would need and how much gas I'd have to carry to run it a lot. - Need more info on this, I understand there's a couple good books out there so I'll have to do more legwork here. 3. Turbo - Good power reliable - Tough to get sharp throttle response. possibly use a light NO2 fog to get thru the turbo-lag zone. 4. Super charger - Instant throttle response, Complicated due to the mechanical installation to drive it. If installed with a bypass it could have very smooth transition characteristics from low to high power levels. I'm still on the vocabulary growth curve so if I'm using the wrong terms please let me know. David Taylor dwtaylor@xxx. My opinions are mine ,, and nobody elses. ------------------------------ From: cal@xxx.com (Cal Smith) Date: Wed, 5 Jun 1996 14:36:37 -0600 Subject: Re: MAF vs MAP >I'd be interested in anyone's experiences using both MAF and >MAP sensors on a single engine. The Toyota 3S-GTE (MR2-Turbo and Celica All-Trac Turbo) have both. The MAF measures air mass while the MAP sensor hooks to a boost gauge and tells the computer if an overboost condition is present. I know this wasn't the intent of your request, seeing as how the map sensor in this case has nothing to do with controlling air/fuel metering, but it has both nonetheless. :-) Cal Smith ------------------------------ From: "Tony Bryant" Date: Thu, 6 Jun 1996 08:47:57 +1200 Subject: Re: How about no MAF or MAP? > From: "Josh Karnes" > I don't have to meet any emmissions tailpipe tests or whatever here > in Austin either, so I am very much interested in ditching the AFM in > my car. I assume that after a certain number of rpms, the ECU takes > over for the miixture curve. It has to sense this rpm somewhere, > right? Which means that there must be some circuitry in there for > determining injector pulse width based on rpm. This must also be > independent of the throttle position. Not at all independent. The figure you need is the actual volumetric efficiency, which is clearly a function of both RPM, and Throttle Pos. The required pulse length is proportional to the volumetric efficiency. > Is it feasible that you could feed the AFM inputs on the ECU with the > output of some circuit comprising of a frequency-to-voltage converter > and some op amps, so you could simulate a condition of the variable > resistor AFM? Basically a voltage is applied to the rail of the AFM, > then there is some resistance, so there is an output voltage after > the drop through the resistor (there must be a reference resistor in > the ECU, I guess). So, with a frequency-to-voltage converter > sampling pulses from the coil, you can convert the rpms to a voltage. > You can then use some sort of variable resistor to find the throttle > position. Use these to drive the input of an op amp that can be > tuned to give a voltage output approximating that of the AFM in the > same scenario. This would adjust the pulse width of the injectors > based both on throttle position and on rpm. No restriction from the > AFM either. Arrrrggggh. Analog stuff! Stay away :-). Why not use a micro? So much more flexible and not at all expensive. I certainly would not consider a purely analog control system in my car! Good luck with your op-amps :-) *********************************************************** * "Insanity is the only sane response to an insane world" * * >> bryantt@xxx.nz << * *********************************************************** ------------------------------ From: doug@xxx.com (Doug Gubbins) Date: Wed, 5 Jun 1996 17:30:31 -0400 Subject: Re: Forced induction on a 2.5 Liter 4 cylinder. >> >4. Super charger - Instant throttle response, Complicated due > to the mechanical installation to drive it. If installed with > a bypass it could have very smooth transition characteristics > from low to high power levels. > >I'm still on the vocabulary growth curve so if I'm using the wrong terms >please let me know. > David, I don't know if this info will be helpful or relevant to you, but I did want to make you aware that there are other types of superchargers than the Rootes blower design that may have characteristics more in keeping with your objective. I'm not an engineer, and I drive a Miata. I supercharged it last August with a Whipple Autorotor Lysholm compressor. The engine is a MAP multiport EFI, and the pulley that came with the SC gives me up to 8 psi of boost. My 1.6L engine is 117 bhp stock. Haven't done any testing, but I'm quite sure I have 50+ more horses. If you don't want that much horsepower, you can install a bigger pulley, or just don't mash the accelerator as hard. The response is instantaneous, and very smooth; you can drive it normally with no boost, or more aggressively with any amount of boost, and the boost comes in at very low rpms. The system has no bypass at all other than the idle air bypass whose inlet was relocated during installation. As for being complicated, I installed it myself over a weekend. The "kit" was from Bell Engineering Group, Inc (BEGI) of San Antonio, TX, and it came with intercooler, custom tubing, assorted castings for remounting and relocating throttle body and airflow meter, a boost-controlled fuel pressure regulator, a piggy-back high pressure fuel pump, and an MSD ignition retarder which I have since replaced with a J&S knock sensor so I can run whatever octane and timing settings I want. Price of the kit was about $2500 at the time, and depending on your enginuity (sp?) in making things fit together, you could probably obtain the same components and put it together for considerably less. This is Miata-specific, but BEGI's web site has some interesting info about their induction kits. The address is http://www.tristero.com/sa/business/bell/index.html. Doug Gubbins Apogee Systems, L&H Technologies Charlotte NC "There's always another bug..." ------------------------------ From: SRavet@xxx.com Date: Wed, 5 Jun 96 16:53:48 CDT Subject: re: Re: Forced induction on a 2.5 Liter 4 cylinder. "David W. Taylor" Wrote: | | Boy did a lot of people answer my question, :) Thanks. | I got enough responses that I figured I'd better give you all a | better description of the goal and the problem. | | I wish to take an engine equiped with MAP and Multi-Port fuel injection | and increse the HP by 20+. Maintaining daily drivability, This is a 4x4 | not a race car, so power control is VERY important. It would be a bad | thing (tm) if I was crawling up a 45 degree rock face and when I gassed | it to get over a small bump I got all 140 HP at once... Mission control | we have liftoff. Un fortunately wranglers don't have a glide ratio. Just a small observation, if you are only (or mostly) off-road, emissions (and registration, I assume) aren't important. Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ End of DIY_EFI Digest V1 #157 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".