Mikelly Posted October 6, 2000 Share Posted October 6, 2000 DO any of you guys know if a GM style TB off a 454 would work on my 383? can it be modified for different injectors in the throttlebody? Can you bolt it to a Victor JR? It would be real nice to go scavage a FI wiring harness and DECU from a wrecked truck, and grab all related FI parts and swap it onto the motor... I know a lot of guys like multi point injection, and I think buying these kits is the absolute best way to go, due to the cost of all the associated parts. You simply will pay mor ein the long run. Keeping my intake makes a TB swap more attractive, which is why I want to know if this can be done... Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 7, 2000 Share Posted October 7, 2000 Mike, I do know that there are adaptor plates available to bolt GM throttle bodies on carb. manifolds. As far as injectors go, higher flow units are available as well. I would suggest getting all sensors (MAP, O2, TPS, etc.) with the harness and ECM. You'll also need too find a suitable fuel pump and plumb a return line to the tank. Hope that helps, I owe you a few! Jeff ------------------ '71 240 '91 TBI 305,700R4 w/ shift kit Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted October 7, 2000 Share Posted October 7, 2000 This is going to be long. I just went thru this on DIY_EFI and will post what I felt was some v. good responses I got here. Worth noting is one normally gets v. few responses on diy_efi BUT those you get seem to nail down the facts. Any errors are VERY promptly pointed out by others if/when they occur so I take their info v. seriously. enough babbles....for breathing over 6000rpm and 400hp they feel the BBC TB won't quite make it but two would, that's what his 'impractical' refers to:-) Read on... ________________ Hey Ross there are three TBI hardware approaches that you may want to consider, if you want to feed a 420'ish HP V8 at reasonable [less than 6000 - beyond is quite impractical] RPM's....... 1) My favourite, due to simplicity and reliability..........Use a BBC 2bbl twin 2" blade TBI [say for example a 17091047 assembly - or anything from a post 91 application will get you the better IAC and TPS setup] with a set of good BBC TBI low pressure injectors [say 17112560 - engraved 17084304] and install a bolt-in-place post 94 BBC 26-32psig TBI regulator [17113079]. This will get you roughly 670 CFM @ 3"Hg airflow, and about 250 #/HR of maximum fuel flow. Oh, and you might as well buy a Holley 12-903 [or 12-903HP] gerotor in-tank EFI pump kit [or maybe even a Bosch GFP216 in-tank pump if you don't mind the cost of this rollervane unit], and be sure to run it all through a GM "spin-on" EFI medium duty truck TBI fuel filter assembly [15694406 - the replacement cartridge is 15577756 - good for 400+ #/Hr flow at less than 0.5psig pressure drop - also allows for use of either the Rochester style fuel line fittings or for the use of conventional pipe thread fittings by screwing out the inlet/outlet adapters]. Use any GM TBI dual channel box that you wish, and program away. Additionally this allows you to use either conventional TBI intake manifolds [which you ***really*** will want with TBI fuel , with EGR if required], or you can adapt quite easily to any intake manifold that you may be thinking of. You won't find this info posted anywhere else on the face of this planet, but it works extremely well, and all of the parts can be obtained via the local U-Pull or your friendly GM dealer, at reasonable cost. 2) My second choice........Is a Holley 4bbl TBI assembly [there were not any OE 4bbl GM TBI assemblies produced - but there were some OE marine 4bbl TBI setups [[volvo]] which were based around the now commonly available Holley TBI assemblies]. Holley has a number of TBI offerings, with IAC, up to a max of 900 CFM @ 1.5"Hg airflow and up to 312 #/Hr @ 15psig fuel flow. These 4bbl units work well, and can be controlled by any GM dual channel TBI box, but external injector drivers will be required. The archives are full of guys ***trying*** to run four TBI injectors from just the two OE GM TBI 4/1 injector drivers [in two series banks], but, you ***really*** want to drive each of the Holley TBI injectors via an individual 4/1 amp P&H driver for best/predictable results. 3) I have not personally tried this last approach..........Dual 2bbl TBI's, a couple of my colleagues have tried this with excellent results. About all I can offer in this arena is that they used dual 5.7 litre TBI's, on an old non-EGR "Offy" style dual carb intake manifold, wired the IAC's in parallel, and used a GM dual channel TBI ECM together with external injector drivers. Seemed to work well, based on their feedback. I'd like some driving time behind one of these, as I have a few unresolved misgivings pertaining to mixture distribution and throttle modulation. __________reply to a few q's I had on above____ >Impractical as in just not needed with an appropriate power band setup >below that? Motor will run to 6500 easily. In my setup I don't need it as >shifts up their are unnerving for me:-( Don't like jumping sideways. I meant "impractical" within the context of typical TBI injector firing schedules versus climbing engine RPM. Most dual channel TBI V8 boxes tended to fire the injectors once each per every other distributor REF pulse (also out of phase with each other) to promote more even fuel distribution. As engine RPM's climbed, the time between pulses would shorten, and eventually a firing frequency would be reached where it was no longer practical/reliable to inject. As most of the OE TBI applications were low RPM oriented, pulsewidth headroom was not a huge concern for the OE's. However, even some of the OE TBI packages had an "escape hatch" which would allow you to revert to time based fueling at fixed (say 12.5ms) firing intervals, based on high MAP and RPM thresholds. Still, this only offered a minor extension in headroom over the previous scheme. In your case, with a healthy 6500 capable mill, you might want to consider stepping right on up to port style fuel. As a saw-off I guess you could try using a GM "port" ECM to run a TBI unit. In contrast, the port box will fire both injector channels in unison at either once per every two crankshaft rotations or once per every one crankshaft rotations. You'd have a lot of calibration manipulation to jump into, if you took this approach, and there are mixed reviews/opinions on exactly what effect the reduced port firing frequency has on idle & low RPM TBI fuel performance. >> Oh, and you might as well buy a Holley 12-903 [or 12-903HP] gerotor >in-tank EFI pump kit >Can I use an out of tank pump? My car was EFI OEM so tank/outlet is baffled >etc. Sure! In fact, you can use the Bosch GFP216 (aka 0 580 254 984) mentioned earlier, as an external pump as well. There are a number of suitable external pump models available, from Bosch and others. I like to put the pump in the tank whenever I can, just because it avoids all the suction/lift problems associated with the external setups and it makes things quieter. If using any portion of your vehicle's OE fuel circuitry then keep an eye open for restrictions, especially on the suction side of the pump. >>conventional TBI intake manifolds [which you ***really*** will want with >TBI fuel , with EGR if required] >Now which TBI intake would I want? I've understood (correction welcome as >usual) OE ones won't flow past 5500 tops. Mine has to flow to 6000 or a >hair below. Fairly simple 'adaptor' I assume to bolt your 2bbl TB above to >the intake? Yes, what you've said is correct. With a bit of porting and clean-up the OE 's can be made to flow quite well, but not to the 6500 type limits you're talking of. Even the aftermarket TBI specific manifolds won't typically do that. In your case you'll want an adapter plate between a TBI and a conventional manifold of your choice. If on the other hand you were only spinning to say 5000'ish RPM, then I'd recommend keeping a TBI specific manifold, if the vehicle was to be anything less than a full-on race car. To give you an idea of what's possible I run a heavily ported OE 93 BBC TBI water-jacketed manifold in one of my applications, and have spent a few days abusing it on the engine dyno. Excellent torque and response, pulls hard way past 5000 (with healthy heads and valvetrain below), and all EGT's would happily hover within a 70 F spread of each other at WOT at any RPM. Plugs almost all looked identical. On the street it's quite a handful. Is fed by the 2x2" TBI mentioned earlier as option #1. >2) My second choice........Is a Holley 4bbl TBI assembly [there were not >any OE 4bbl GM TBI assemblies produced >-now I do know of a holley 4D setup that's their 700cfm model barely used >for $325US, seems high for the TB but I guess I'd get >pump/injectors/regulator etc as well and I could drive it with GM ECU if I >wanted?? That might be a good route to try first, if wanting to stick with TBI. These Holley 4bbl's are fairly decent units, and can be easily adapted to most carb manifolds. You can run it with almost any GM box (remember notes above), but make sure that you have an external driver arrangement between the box and the injectors. You want one 4/1 driver per each Holley injector, and you also want to keep the fuel pressure at no more than 15-18psig otherwise the injectors will lock-up. You can use the pumps and filter mentioned earlier. I've also seen the 900 CFM units floating around on E-bay and such places. Just make sure you get one with IAC, and make sure you flow & check the injectors before you use it (hint-hint-hint.). >[i have a hard time getting my mind around 2-2" blades feeding 400hp when I >see same inlet size on prepped 240Z's. Obviously they're not making max use >of that inlet as they're not running twice my rpm to ingest same air.] It's all based on your individual application's breathing requirements. The 2x2" flows 670 @3"Hg pressure drop. You'll have to estimate your peak airflow, and compare that to the setpoint above. A 2x2" would probably be a notable restriction in your case. The Holley above sounds like a better deal, or better still go port. >Now possibly from outside misinformation I have assumed I can't do this >'custom/plug'n'play' setup with multiport? 747 ecu etc is all TBI is it or >can it be used on multport? Costs of ECU and injectors were holding me >back from multiport. I've seen 30pph SVO and bosch/takeoff injectors >regularly on ebay etc for quite cheap ($50 and up) but have been told I >should run 36pph? If a the GM ECU can be cheaply used for TPI as well I'd >love to hear about it as I just realized I'd assumed from outside info this >could not be done and seeing the plethora of info/experience on this list >I'm hoping I might be told otherwise? >Ideally I'd like MPI plumbed on my Vic. Jr. if I can find the system within >my budget. TBI could be fun meantime if MPI is too pricey. It would be quite easy to step up to a roll your own GM port system for about the same cost as TBI, and honestly I think you'd be happier with the finished results in the long run. TBI fueling can be pushed to higher than OE anticipated power levels, but this is usually only done in cases where people either 1)see TBI as an intermediate temporary step before going port, or who 2) "have" to stick with TBI to maintain compliance to state/class laws. _____________________________ first quoted post has some info worth saving/FAQ IMO Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 7, 2000 Author Share Posted October 7, 2000 Priceless info ROSS! Thanks a lot! Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted October 8, 2000 Share Posted October 8, 2000 Mike - pay special attention to the fuel pressures mentioned here. With a simple spring change the Holley Blue pump you've been using should be able supply the 18# max pressure - a cost savings. Pumps liek what I've got on my Mustang and on that LT1Procharger car cost upwards of $250+ - doh! Personally - I still like port injection better but I won't rain on anyone trying TBI - it works too! One thing I AM interested in though - who has or where can I get the software for reprogramming a GM PROM for this? I've got software for the Buick GN but never seen anything else. Is it out there readily available? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 9, 2000 Share Posted October 9, 2000 I know there are several editors available for GM PROMs. "TunerCat" http://www.tunercat.com is one I've heard of. Another is WinBin http://www.spiritone.com/~eoa/Cars/EFI/index.htm Here is another good link for all things GM ECM oriented -> http://www.diy-efi.org/gmecm/ I'm in the process of deciding whether to venture into the PROM programming world myself, or pay the "experts" to do custom work for me. Jeff ------------------ '71 240 '91 TBI 305,700R4 w/ shift kit Quote Link to comment Share on other sites More sharing options...
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