DIY_EFI Digest Saturday, October 16 1999 Volume 04 : Number 583 In this issue: Intro and SB Chev Recommendations... Re: DIY_EFI Digest V4 #580 Re: DIY_EFI Digest V4 #582 RE: MEMS See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Fri, 15 Oct 1999 14:44:16 -0700 From: Doug Dayson Subject: Intro and SB Chev Recommendations... Hello all...my name is Doug Dayson...I live in the San Francisco Bay Area in CA...I'm a musician/audio engineer/producer and software engineer by trade... I'm currently researching converting my modified 71 Corvette Coupe to EFI...mostly because I run around with a club of people with newer Vettes that are injected and when we get into higher altitudes I can't compete w/o rejetting (which is a hassle) so... The Vette weighs 3200lbs with a half a tank and no driver...it has a "stock short rod" 406ci/375hp small block chev with TFS Aluminum Heads...Edlebrock Performer Manifold and modified Q-Jet carb...1 5/8" X 3" headers...hyd flat tappet cam timing is 218 @xxx.it currently makes around 450 ft/lbs at 4000 rpm and 375 at 5000 rpm (all gross at the crank)...BTW it's already been converted to HEI ignition... It has a 89 700R4 four speed automatic trans with a 3.08 rear gear and 25.5" diameter X 8.5" wide tires...it's best at Searspoint Dragstrip (330 ft) has been a 12.87 at 112 on street tires (shifted at 5500 rpm)...amazing enough it does on average 19 mpg at cruise with the carb "IF" I keep my foot out of it (thanks to the OD and Lock-up Torque Converter)...a pretty good all around street motor...idles good...gets decent mileage...goes good etc...I guess I'm looking mostly to keep the same power curve (or better) and enjoy the increased driveability and economy that EFI can produce! Also of note...it's now smog exempt...though I'd imagine that any good EFI setup will improve tailpipe emissions which is good! And...hoping to do this swap with the engine in the car...so no engine dyno time...could do chassis dyno though if needed...expensive though! After all...as a pricing guideline..for $3700 you can get a "brand new" complete GM LT-4 350ci Crate motor (330 Hp Net) with GM EFI... So...with the above in mind (including my status as a EFI Newbie)...recommendations (for hopefully) under $2K complete on a conversion concept? 1) TBI or MPI...one issue is my fuel tank return line enters the tank up high (above the normal fuel level...hoping to not replumb the tank)...would this be a problem with MPI's higher fuel pressures vs TBI's lower pressures? 2) Agreed...the Accel Super Ram would make the best performance...BUT...too expensive...might not fit under hood...would probably kill the trans in short order (due to the extra torque)...best pricing seems to be Summit or Jegs...approx $1500 for manifold...runners...and TB...still need $700 + for GM sensors and ECM...chip and harness...fuel pump etc...$2200+ for parts...$3000 from Accel with Accel DFI ECM...and the GM ECM gives Altitude Sensing...Spark Control...Torque Converter Control...and Limp Home Mode all standard...these are all extra cost "options" as I understand it for Accel's DFI......what do you think...is there a better way? 2a) Accel DFI vs GM ECM with proper WOT calibration? 2c) Anyone using the FP Performance ECM with the wide band O2 sensor...for closed loop at all times including WOT? 3) How about the Electromotive kits? 4) How about the Howell TBI kits with the Holley TB and GM ECM? 5) I don't think that a modified TPI (big manifold...big TB...big runners and ported plenum) would be able to support a 406ci to 5500 rpm...is this correct? 5a) I also imagine that a modified as above TPI would cost as much as a Super Ram wouldn't it...and not be as effective? 6) Looking through the archives showed that most weren't happy with the Holley TBI...or Howell TBI...anybody have success with either of these systems as the pricing is right? 7) How about the single plane carb manifolds plumbed for MPI from Holley...Accel...Arizona Speed and Marine etc...anyone having success with these on the street? 7a) I understand that in a wet/flow manifold design the single plane would lose torque in the lower rpm ranges (under 4000 rpm or so vs a dual plane)...and that my conservative cam timing wouldn't allow the higher rpm needed to really use a single plane manifold...is this still the case in a converted to MPI single plane manifold (now dry/flow)...seems like the air velocity and cylinder filling would remain constant with or without the fuel being introduced? 7b) I know that Arizona Speed and Marine will plumb a high-rise dual plane manifold for MPI...anybody try such a thing? 8) Anybody use the Barry Grant VFI TBI? 9) Anyone try the TPIS Mini Ram? Sorry for the length...looking forward to your replies! Thanks a lot...Doug ------------------------------ Date: Thu, 14 Oct 1999 04:33:53 +0200 From: "Espen Hilde" Subject: Re: DIY_EFI Digest V4 #580 > > Mercury delivers a high perf 200 dfi that took 2 place at paris ruoen 24 > > hour (river) race.The ability to run lean burn conditions is great for > > reliability as I see it. > > Do they really deliver it? Given that it has a lower unit that can't > reverse, it wouldn't make much sense for anything but racing. I think they used a standard gearcase, they didnt have to change the lower unit during the race.They saved lots of time that way. I havent sen any pictures or description of the lover unit they used. And as a racer > you get more power per cubic inch from an XR2, 2.5EFI or even a 300 ProMax. > > > I have 2 2.5efi high performance engines that I am reparing, line boring > > Are they any fun? Just problems so far, but nice to look at with mahle forged pistons, lots of ports .aluminium Nicasil treated sleeves. Big reed blocks. and the v8 inspired trottle body.The loverunits are beauties, I have a slightly modified Yamaha 225hp with nose cone that I have to fill with padding all the time, I want to weld it but maybe it will change because of the heat.Maybe the new lowerunits from Yamaha with biger skeg and low water pickups has the same gear and internals as the one I have . I have very modified Yamaha 200 What modifications have you done? that will get an EFI > system if it is still running when I can aford one (eg MADEFI) or find time I have looked at the mad efi myself, no I am hoping that 332 efi would do the trick. I would like to play with the ignition also... Do you have any info on recalibrating the ignition system on the Yamaha engine? > to build something... Performance below 4000 RPM is not exactly stunning when > using carbs. What hp does it make? I read somewhere that the ox66 engine used GM corvette ecu. > > They have analog efi with old d-jetronic peek and hold injectors.(As > > standard) > > Is this the 260hp version? Yes. > > The new 2.5 efis has digital boxes ,Motorolabased. > > The 280hp machines? Yes. Espen Hilde ------------------------------ Date: Fri, 15 Oct 1999 18:49:02 -0500 From: nacelp@xxx.com (CSH-HQ) Subject: Re: DIY_EFI Digest V4 #582 Massive snippage >What kind of filler do you use on the nose cone? (Mine is welded, and the >paint is coming off, but the putty stays...) > Personally, here at Cone Shaped Hat, HQ, I think spandex, would make for a good fit rather then filler.. Might start a trend wearing a hat on one's nose, maybe Dopey will volunteer, for the fashion segment.. Or use a spanddex liner, with the usual fannel/fleece outter shell. Hmmm. Has anyine seen any four strokes other then the Mercedes v-6 sedan car using an expansion chamber (s), like a 2 stroke. Any thoughts on why this might really be worthwhile, or just a cosmetic gimmick. Would have thought other teams would be working with it by now if it made a hill of beans difference... Cheers Grumpy Hey Dopey, where are ya??. ------------------------------ Date: Fri, 15 Oct 1999 20:15:00 +0100 From: Ade + Lamb Chop Subject: RE: MEMS At 05:00 15/10/99 -0400, you wrote: >>What does the knock sensor do? What does it mean if I don't have one > >Detects the onset of knocking and dynamically reduces the ignition >timing advance to minimise it. Not all the systems implement knock, >If you chose to use a system that does, but don't want to use it (or >don't have anywhere to mount it) the best would be to have the sensor >connected so that it doesn't create a sensor detection fault; the >system will never see a knock signal, so will perform normally. My Rover manual doesn't mention a knock sensor so it cannot have one. (and we all trust rover don't we....yeah right) The manual says it plays with the timeing at idle. But I presume that once it comes off idle it just uses the map of MAP/REVs >I think it's to do with hot start strategy when there could be the >possibility of fuel vapourisation in the fuel rail. I've only seen this >fitted on MPi applications, where the sensor is mounted on a boss, thermally >attached to the fuel rail. Sounds reasonable.... >>>All MEMS systems control ignition, either single coil or distributorless. >>>All systems use a stepper motor controlled throttle stop for idle speed >>>control. > >>Apart from the Mpi (97 on) minis which have a bypass valve which bleeds are >>from the filter casing into the manifold. > >I wasn't aware of that - I've only ever seen steppers.... we live and learn. It is a stepper motor. But instead of an adjustable butterfly endstop. It is a 'pintle valve' (what ever that is) Which is adjusted by a stepper. The valve is mounted to the manifold where it does the turn towards the head. It has a hose that goes from the valve up to the filter side of the throttle body. Ade ------------------------------ End of DIY_EFI Digest V4 #583 ***************************** 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".