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tbi 383

Discussion in 'The Garage' started by gotchevys?, Nov 9, 2005.

  1. gotchevys?

    gotchevys? Registered Member

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  2. shane74

    shane74 1/2 ton status

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    Before you spend the $$ on it, do the research. Check out this website.
    http://www.tbichips.com/truckmods.htm

    There is a lot you can do to your stock TBI 350 and even turn your current TBI 350 into a 383 fairly cheap/easy if you take the time to do your research.
     
  3. SnackPack

    SnackPack 1/2 ton status

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    I recently built my stock 350 TBI into a "stock" 383 TBI, and have had no problems.

    Those sites say alot about chipping and so forth, but you can built your TBI 350 into a TBI 383 without a new chip.

    I went with the cheapo Eagle ext balance crank, dished Speedpro hyperuetectic pistons, stock heads, stock TBI, and a Comp Cams XE256H cam: http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=12-234-2

    I plan on bumping up the intake and heads sometime soon, but I found this to be a decent setup if your budget is low and you just wanna get the 383 bottom end in.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Didn't someone on here with a 383 burn holes in the pistons with a stock TBI setup?

    Without making mods, TBI WOT fueling on a larger engine is going to tend to go lean and you'll never know it. Well, until the engine exhibits problems that is.
     
  5. SnackPack

    SnackPack 1/2 ton status

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    I haven't gone WOT on it yet as I'm still breaking it in, but once I got the exhaust hooked up, I haven't gotten any check engine light. Went to heated o2 sensor as well.

    *edit* it stays very cool, too... always under the 200 mark on temp guage.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    WOT fueling isn't calculated by the O2 sensor, again, you'll never know there is a problem until the motor comes apart.

    Fueling is handled by the preprogrammed fuel curve at WOT, (along with timing) and even with the fueling and timing curve modified, the injectors may not be capable of flowing enough at higher RPM's to compensate for the demand.

    Go do some reading over at thirdgen.org, I'm sure there are plenty that have done a 383 swap, perhaps even with TBI. Conceptually not much different than a 383 TPI motor though.

    There's a post here about a TBI motor melting pistons though, you'll find it I suspect, if you look.
     
  7. shane74

    shane74 1/2 ton status

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    If you build a 383 TBI, you absolutely NEED a new chip and higher flow injectors. Also, it is highly recommended that you either buy a higher cfm TBI unit, or do the 50mm upgrade to your current unit. You will burn up your engine if you ignore the fuel delivery system.
     
  8. SnackPack

    SnackPack 1/2 ton status

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    I understand the lean mixture issue, but isn't that if you're really getting on the throttle?

    For instance, wouldn't you be fine if you don;t max out your fuel intake capacity at higher RPMs and start going lean? Would the camshaft affect this at all?

    Also, would you know why I haven't experienced this meltdown yet? I've been basically keeping it under 55, under 3500 RPM since I built it.

    Fuel system upgrades have always been on my radar, but it's not in the budget yet.
     
  9. K5Steve

    K5Steve 1/2 ton status

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    If you're still breaking it in I doubt it would've had enough time to melt down.You don't really know where the cut off for the point where it goes lean unless you hooked up a wide band o2 meter or had it dynoed.I would take it to a dyno and run it just to make sure.I would want my new engine to fry out.You never know,it may not be so bad that it would damage it but you won't know till it's tested.
     
  10. SnackPack

    SnackPack 1/2 ton status

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    So a dyno shop could tell me if it gets lean at a certain RPM? That's great, I've been wanting to get it to the dyno anyway.
     
  11. K5Steve

    K5Steve 1/2 ton status

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    They will tell you exactly where it is going lean.They will time and adjust everything to get you the most power from your setup.All the more reason to get it done. :D I know I am when I get my new motor,better to be sure right off the bat.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    I will qualify that at this point I am certainly no programming guru, which is why I suggest doing a lot of research on the forums over at thirdgen.org. It takes a lot of reading to even begin to understand some of this stuff.

    Power enrichment I believe is where you start getting into trouble, and that isn't at "WOT".

    If the right conditions are met, even with a less than optimal setup you may not have any problems, or, if conditions are just not right, you may have the worst possible result.

    I know that some shops have the ability to burn PROM's during the dyno session, (or you can use the dyno sheets to get a PROM from the internet) but that's still not as optimal as running it on the street and getting it perfect, which is only going to happen if you learn to do it yourself.

    Dyno testing is in a controlled environment and doesn't allow for variations such as the engine load of pushing a 5500lb brick at 60MPH, or different temperatures, both ambient and underhood.
     
  13. SnackPack

    SnackPack 1/2 ton status

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    Wow dyeager, I think you've sparked a new hobby for me. I made a WinALDL cable and checked out some of the data.... *very* cool. I've got some more research to do, but I did notice that my BLM goes from 128.6 @idle to about 136 @3000RPM. Do you know if this is a dangerous mixture?

    I spoke with the tbichips guy and I'm gunna order a chip for my setup, but until it arrives I'd like to know if it's safe at these numbers.

    So I think I'll just get this new chip (and the .bin for it if he'll give it to me), familiarize myself with WinALDL and its output, and spring for a PROMinator before I start upgrades in the spring.

    Adam
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    IIRC, the higher the BLM, the leaner it is, the more the ECM is trying to compensate. You want it around 128 across the board, or pretty darn close. I don't think 136 is REALLY high, but I also don't recall what the max BLM reading is. 160?

    Did you run winALDL while you were driving? I don't know about '747 ECM, but the 160 baud '165 ECM's lock the timing down, along with raising idle to 1000RPM's, so I'm not quite sure how you'd get a completely accurate log. I thought the same thing, if idle is forced to 1000RPM while datalogging, how can you know if "normal" idle is rich or lean?
     

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