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More performance while still running TBI.

Discussion in 'The Garage' started by 1-ton, Nov 9, 2005.

  1. 1-ton

    1-ton 1/2 ton status Premium Member

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    I was thinking of getting a stroked 383 for my "V" series Crew Cab with TBI, but after looking at a lot of different information, I have decided that running a 383 with TBI takes too much custum fuel and ECM tuning to be feasable, and still be smog legal. There are two other engines GMPP has. One is the HO-350/330 HP (Vortec heads), and the other is a 350/290 HP crate engine (no Vortec heads). Which one do you people think would be the easiest to deal with as far as being able to get it to run correctly with a minimum of off the shelf TBI fuel system upgrades and ECM modifications, yet still be smog legal. I would like an engine with Vortec heads.

    [​IMG]
    HO-350/330 HP crate engine

    [​IMG]
    350/290 HP crate engine
     
    Last edited: Nov 10, 2005
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Smog legal as in visual or numbers?

    Vortec TBI is a nightmare for EGR, as the custom intake is expensive, and you've got to plumb a pipe from the exhaust to the intake.

    Older heads don't have that problem (they have the exhaust crossover in the heads) but the performance isn't what it can be from Vortecs.

    Vortecs also don't like the timing curve used with the older heads due to their construction, and I can tell from personal experience, it won't run optimal without messing with the timing in the PROM, and that's beyond an off the shelf chips ability.

    Along with the cam differences of any "HO" motor that would be installed, I'd be leery of installing a motor into an EFI application without expecting to get into the PROM side of tuning.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Your factory TBI was fine tuned by GM to feed a 200 HP engine. It simply isn't capable of feeding much more than that without tweaking. :( The further you go past 200 HP, the more tweaking it's going to need...
     
  4. 1-ton

    1-ton 1/2 ton status Premium Member

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    The numbers...visual is easy to comply with in the state of Nevada. I do not understand why GM saw fit to install a puny little 200 HP small block into a 6000 Pound truck? I wonder if going to a 454 TBI engine would be easier? The only thing that concerns me is cross-member to oil pan clearances with a 454 in my "V" series Crew Cab Straight axle Pick-Up.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, straight across TBI to TBI 350->454 wouldn't be difficult at all, but the PROM is different and I believe a bit of the wiring is too, besides the throttle body itself. If you could get the 454 specific stuff, it would be an easy swap.

    It's been awhile, but last I looked the TQ numbers of the truck motors was still pretty decent even with the pathetic horsepower. Definitely not as concerned with HP as they were with TQ.

    As long as compression was still in the 8-9:1 range, (and even if it isn't) I don't see a reason why a stronger motor couldn't be passed based on a sniffer test. Again though, timing and fueling are going to be your enemy when it comes time to pass the test, and that goes back to the PROM.
     
  6. 1-ton

    1-ton 1/2 ton status Premium Member

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    I am thinking this is the way to go. Buying a factory TBI, ECM, and wiring harness for the 454 would not be that big a deal, as compared to the hassle custom tuning a PROM for a higher horsepower small block would be. I know I would have to put a completly new exhaust system on my truck with a 454, but I wonder if my drive shafts would be the correct length for a 454?
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    I don't see why you can't re-use the small block harness. At absolute worst might need a bit of soldering to lengthen a couple of wires, but that would save you hundreds in the harness.

    Looking around online, you can probably even find someone to burn you a stock PROM for whatever year 454 you end up, which would also save a fair amount of money I'm sure.

    Drivelines will be fine, BBC just sticks further forward. (different radiator shroud) Did the swap in my dads truck, no problem.

    Even the exhaust could be made to work depending on what you have now and how good shape its in, I just hacked mine off far enough back to connect the headers, (going from manifolds) which required just a few welded in short pieces of pipe. Are BBC exhaust outlets different diameter than typical small block? Am I right in guessing that you have stock single, probably 2.5" though?
     
  8. 1-ton

    1-ton 1/2 ton status Premium Member

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    I guess swapping in a GoodWrench direct replacement 454 (part #88890529) is the best way to go. This solution allows me to just buy some off-the-shelf parts to make it work.

    All I will need to do to increase performance is swap in the 454, Install a hotter, yet still computer freindly, camshaft (part #12361316) with 210/218 duration and 485/490 lift @ .50 in, Install an Edelbrock aluminum square bore manifold, Install factory TBI adapter, install a Holly direct replacmentTBI (670 CFM), and install a TBIChips.com stage 1 PROM. The ECM part number #1227477 for my original 350 is the same part number as the ECM for the 454. I have allready installed the radiator and shroud for a 454 in my truck.

    Specs on the 454 part #88890529:

    255 HP @ 4000 RPM

    415 Ft. Lbs. @ 2000 RPM

    Compression Ratio 7.9:1

    Camshaft Specs @ .50 in

    Lift: 234 int/252 exh

    Duration: unkown (not much I am sure)
     
  9. d'cheat

    d'cheat Registered Member

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  10. 1-ton

    1-ton 1/2 ton status Premium Member

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    I have looked at their engines, and some other companies that also offer similar smog legal 383 stroker engines. What they do not bother to mention is that it would take an enormous amount of modification to run an ECM controlled TBI setup with even those engines. Any engine that runs over 260 HP takes a lot of modifications to run an ECM controlled TBI. The biggest off-the-shelf TBI there is only flows a maximum capacity of 670 CFM, and that is only in optimal conditions. The real world CFM capacity of this TBI is about only 610 or so. A 310 Horsepower 383 would probably need a TBI that flows a minimum of 700 to 750 CFM to run right. It would take a lot of custom PROM tuning to control a 750 CFM fuel curve. This is why I want to go with a big block 454. I can get a 454 to put out 400 Ft. Lbs. of torque, yet still have small air and fuel mixture requirements.
     
  11. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    If you need a factory 454 TBI adapter i have one i'll sell you. $40.00 plus the ride.
     
  12. mini_mull

    mini_mull 1/2 ton status

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    If you haven't already, email or talk to the guys at turbocity.com. They seem to know their stuff, and a few guys on here have recomended them. They can help you get your TBI to feed about a 330-350hp engine without switching to a 454TBI. They told me they used to reccomend the 454, but after some problems, only reccomend their bored 350TBI for SBC apps. Check out their packages that come with everything you need for the swap.

    If you go to their website click on TBI specialties from the menu on the left, then upgrade kits, then TBI Performance. You'll see the Vortec head stuff in the first section.
     
  13. 1-ton

    1-ton 1/2 ton status Premium Member

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    Again, we are talking a lot of custom ECM PROM tuning to make that work. What I want to do is make this project as simple as possible by using nothing but "no fuss" bolt on parts. With a very mildly cammed GoodWrench 255 Horsepower direct replacment 454. I can get away with just bolting on a Holley direct replacment (670 CFM) TBI, with a cheap, off-the-shelf, one size fits all PROM chip, and still produce over 400 Ft. Lbs. of tourqe.
     
  14. mini_mull

    mini_mull 1/2 ton status

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    No experience personally, but you might want to do some searches for threads on that Holley. When I was researching it, there were quite a few guys who'd posted threads complaining about it. Whatever you decide, post up and let us know how it goes. :D
     
  15. 1-ton

    1-ton 1/2 ton status Premium Member

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    You have a good point there. I am going to do that.
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

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    I'll back up the Holley deal. From what I've seen, it seems like they've got way too many issues with their TB's to deal with.

    Someone on here did a really nice writeup on a TBI swap, (linked from a post on this board) which included a not so glowing review of a bored out TB. It was good reading though, and covered the whole swap IIRC. The writeup was on a separate web page if that helps narrow down where it is.
     
  17. Thunder

    Thunder 3/4 ton status

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    If you want to get the Gm 330 H0, run TBI and keep it simple. Just go here cfm-tech.com they have a nice kit including: TB, Chip, and injectors that will make TBI work with the 350HO. You can also get anything else you need from them to make your TBI engine perform.
    Also as said in a previous post http://www.turbocity.com can help you. I have dealt with both people with performance TBI issues. They both are very helpful. Cfm-tech uses Turbocity's blurprinted TBs and some other parts. They also have chips that will make a 383 run with TBI as long as you use a cam they recomend.
    With TBI, you wont develop the advertised power that GM says out of the 350 HO or the crate 383 because they were dynod with a carb. But you can make both engines run very well with TBI.
     
  18. BigRed89

    BigRed89 1/2 ton status

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    I had a 383 in an '89 Sub in SoCal, and it passed smog without any problems. The cam was a custom grind with torque and smog in mind. The only thing you need to switch out is the computer chip. This is a very simple / easy thing to do. I doubt NV's smog requirements are any more strict than CA, but I could be wrong. Don't be afraid to try a 383 in your smog vehicle. As previously stated, cfm-tech and turbo city are great sources of information.
     
  19. jboyes

    jboyes 1/2 ton status

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    sounds like alot of work and a lot of money to go the way of the 454, and my personal opinion is that you will run in to more problems than you are prepared for when you actually get in the middle of it. If your looking to keep it a little more simple, and ALOT cheaper, I would suggest finding a pair of vortec heads, buying the GM intake (don't have the part number in front of me but it's on their website), and bolting it all together. The only other mod will be the driver side mainfold from a vortec engine that should have the egr tube still attached. No computer tuning should be necessary, but an aftermarket chip probably wouldn't hurt anything. My little brother is about to do this exact thing in his 95 Tahoe in the next month or so, I'll let you know how it turns out if your interested.

    oh, and don't forget to buy the head gasket set for the vortec, not your tbi!!!
     

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