I want to build a street 403 with a turbocharger..low boost

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Old August 22nd, 2016, 04:41 PM
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i have the turbo mocked up and the fuel injection manifold is on the motor...i am working thru the throttle body availability that will work...i am going to have to do some milling on the intake to make it better..i need to cut the top off and put a turtle on the floor..but it will all be hidden under the TB..the main reason is the manifold is cast in a way there in no real plenum under the carb..the gap between the bottom of the casting and the floor is less than an inch in one spot, it has a bunch to do with heating the TB and EGR...i dont like that..i know its a dry intake..but..theres no way it has enough plenum volume with out some surgery

next hurdle is accessories..and i am using everything off an 80s 307 i found on CL...it uses an A4 compressor and that gives it enough room the turbo fits and looks like a factory install...oh..yeah...its gonna have working A/C..because its a challenge..lol..and it gets ruff in KCK in the summer..lots of heat a and humidity

i cant weld like i did when i was on the line beating on cars..so its tacked and this weekend my welder buddy is going to weld it all up..i made some jigs to hold it all together for the trip..i just cant tig the tubes together nice..ive been practicing..but having probs on the thin tubes.....and i realize its because i cant "see" like i used to..so i made a doc appt for an eye check up...it really sucks getting old..

i will post pics in the next week or so.. from start to the point i am at now...

yes its injected..and thats going to be a surprise to most everyone..its almost all used GM parts, and its multi port too....i did it because i could..and it was dirt cheap..and keeping the cost down was the plan..its an Olds 350 multi port off an 80s cadillac..didnt even know they made one til i found it on this site...i have to swap the TB and i dont want to buy one..and have a plan..and i will lay it all out..

I have the Caddy TB but its so ancient the IAC and TPS wont work with anything and no MAP sensor...but i have it all figured out..i will lay it all out..its a lot of google work..but i could never have done it in the past..the internet is an incredible tool

injection fixes a lot of fuel supply probs/issues that a carb has..for cheap..no real performance gain...just tuning and ease of use really..and i want to do it..its a challenge

i am going to get a mega squirt kit...ive been practicing soldering small "build-it" kits from radio shack..its been 35 years since i soldered on a circut board..i built a digital clock and it works..lol..and some LED christmas ornaments etc..and forgot how much i like it..the mega squirt comes in a kit..you build it..and build a test device to test run it.i thought id try the kits to see if i can make it work and follow the directions on how to build it...and i can..the first one was a little tuff..but the rest is cake..i feel i can do/build the mega squirt...i thought id rather ruin a $10 kit than ruin the MS

the only thing i went off track is..i bought a 2004R as a running trans...its off a 83ish OLDS Diesel wagon and has the BOP pattern..it needs a governor swap and re-cal on the valve body and a diff converter...but i have a hook up for it...i have to put a trunk pan in a chevelle for the swap...i paid $150 for the complete trans as a pull out

i bought a complete turbo system for a SBC off craigslist..i stole it..the guy got tired of relisting it and i offered $300 and he took it, he said 12 people where coming to get it and i was the only one that showed.....it has 2 turbos,and one is new fresh...and i will cherry pick it and sell the rest off and get the turbo for free...its an OLD rajay turbo rated for 450 HP on a SBC at 5500 rpm..so it works right into the idea of low boost and rpm..should do about 400-425 on the 403 at about 4500 to 5000 rpm...if not its a T-4 and i can swap it out later...

i found a real cool 70s carb hat off a Banks system for a boat..it has some engineering in it..for $10 bux at a swap meet...it looks like it was made for this set up..i gotta say...its really coming together..

I am working on a good post..ive loaded some pics etc and am working on it to make it understandable...and pricing/trading info..no fudging the numbers either..its happening...i am moving forward..as a matter of fact...i am on my way out to the shop with my fresh traded TB to see if it will work like i think...i'm really excited about this project..

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Old August 24th, 2016, 05:23 AM
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I like some of your approach but from the sounds of it that intake/TB will be a power killer, even with boost.
I did the EFI on a twin turbo stock 2 bbl 307 SBC in 66 Nova for a guy here in florida. He wanted to get it all mocked up before he dropped in his built 383. With 20# of boost the 307 barely made 500hp. It simply had no air flow. With the 383 it made just shy of 1200 on 25# of boost.
I know your goals are conservative but you might want to re-think the induction pieces.

Jmo
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Old August 24th, 2016, 07:31 AM
  #43  
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my intake is an open plenum (after surgery) single plane..once i mill the bumps out of it, it has the plenum volume to support the 403.....the throttle body flows 670 cfm stock..once i get it running..i will switch it to a modified version thats been cnc'd to 725ish

my horse power calcs are with 7-8 lbs of boost,,its all i need...low rpm..low boost.....the turbo will support 425 to 450 hp at around 4500- 5000 rpm for 403 cid.....the 403 is rated at 185 net stock......not looking to break records..or the dyno...i want a tire burner that easy to drive and fun....

heres my turbo needs

7.72 psi
49.5 pounds per minute
614 cfm

450 hp
4500 rpm
403 cid

i barely meet those goals with the turbo off the chevy set up..but its right there..so it should be fine..if not..i will do a turbo upgrade...just modern wheels in it would make a leap..but..i want to get it up and running..and its the fastest way to accomplish it..



LOW BOOST>>HIGH TORQUE>>>>LOW BUCK....its all i'm looking for....

Last edited by marxjunk; August 24th, 2016 at 09:59 AM.
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Old August 24th, 2016, 01:53 PM
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Originally Posted by marxjunk
low rpm..low boost.....

Just remember, high load/tq at low rpm is hard on parts, especially with a 403.
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Old August 25th, 2016, 06:12 AM
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What throttle body did you end up using?
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Old August 25th, 2016, 08:15 AM
  #46  
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DODGE 5.9...

i looked and looked...i could buy a CNC billet 4150 style TB..but it really kills DIY low buck approach...i am keeping it simple..and very stock looking components...if it doesnt work..then i will spring for an aftermarket piece...for 2 days, i was researching modifying a 750 holley and transforming it to be a dry TB...but why make it hard..this 5.9 TB is bolt on...i will spend the money and effort on a cam etc


it has all Delphi components..the TPS AIC and MAP is all delphi..i did a cross reference and they all have GM specs/uses..i feel why make it hard, use proven stuff..it took a week every night researching til i figured it out..i wanted to make sure i could use the sensors and where compatible and supported/proven with the mega squirt..its was either Delphi or FOMOCO stuff...they are supported the most in the aftermarket ...

its small/short compact, a very clean look/quality, has an air cleaner flange like a Holey and doesnt need some welding to close it up or clean it up like a GM TB would need...and theres aftermarket support..like the CNC stuff etc..it is a 2bbl but the CFM is on target of what i think i need..i have a used one..when its running..i will get a CNC modified unit...
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Old August 25th, 2016, 11:47 AM
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I'm still waiting for moc up pics...
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Old August 25th, 2016, 03:00 PM
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Great part is it also has a 5 1/8" air filter flange. I need a ported one.
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Old September 11th, 2016, 07:30 PM
  #49  
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damn welding guy is screwing me around...just like all fab guys do...

the 403 is running with the fuel injection and no turbo..i decided to get it running before i made a bunch of drastic mods...my computer buddy has a twin turbo injected race car and he set the mega squirt up, he has done a few and understands sit..i am totally lost..lol

..i built/assembled the MS, and he tuned it..and it was hard for me all of it..took a lot of time....i grew up before computers and have just plain painted way too many cars without a mask..i kilt too many cells for it..its above me and too old to change..not sure i will do it again on my twin turbo 425....ooops it slipped out..didnt it..i will inject it..just something more "idiot friendly"

he has about 8 hrs in it, and says he will have 3 or 4 more in it when totally done....and seems to have it running well...we cant really drive it yet, i have a few other things going on before the drive phase...but it pulls on its own etc but it goes up the drive and shifts so better than i expected....i have a ton of crap going on for work and will be out of town quite a bit for a while but should be home most weekends..i'm so excited it runs and drives (kinda drives)...

next weekend we will see how it goes if i make it home...thats all the info i have right now..i have been making notations and keeping track and taking pics of the build..i will post a build thread stuff as soon as my welder dousche gets my stuff done ( he knows he's a dousche..he will admit it)..

i am waiting til i get a little further, because i dont need to hear what i am doing wrong etc..its a learning experience and not interested in arm chair criticism lol..but its going well..i should be driving it in october...then back on a resto i blew off this summer..

Last edited by marxjunk; September 12th, 2016 at 03:52 PM.
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Old September 11th, 2016, 08:29 PM
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Restos are boring, any project involving boost is fun. Still waiting for pics... Btw compound or parallel for the twins?
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Old September 11th, 2016, 08:57 PM
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parallel..i saw pics of a set of manis made from a set of TORO manifolds...they cut the flanges off and welded v-band adapters on..pretty slick..i already have the stuff so thought why not try it too..lol

im not sure on injection on it..i want to use an inter cooler and etc..i'm thinkin blow thru with corn e/85...but its next summers deal..
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Old September 12th, 2016, 12:47 PM
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Originally Posted by marxjunk
"idiot friendly"

he has about 8 hrs in it, and says he will have 3 times that when totally done....and seems to have it running well...we cant really drive it yet, i have a few other things going on before the drive phase...but it pulls on its own etc but it goes up the drive and shifts so better than i expected...i'm so excited it runs and drives (kinda drives).
OMG ARE YOU FRICKEN KIDDING ME? If it takes more than 3 hours total then I'm sorry, he's a lousy tuner. I don't care what he's done before. Apparently he's not done it very well.
Boosted applications are actually easier in some ways and therefore can be more forgiving so his might seem to run ok. But seriously, really, if he needs more than 2 hours to get your mild N/A vehicle "kinda drivable", he's BEYOND lousy. OH MY GOD!!!!!!!

Last edited by cutlassefi; September 12th, 2016 at 01:04 PM.
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Old September 12th, 2016, 03:48 PM
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first this was a learning experience...it wasnt a race and i didnt pay him for the labor......i guess i over understated it/mis spoke..theres a whole bunch more he did in 8 hrs..a bunch...my bad..

he just about rebuilt the whole body wire harness..fixed the rigs on a 30 year harness which meant pulling the fuse box and dash harness out and replacing a bunch of stuff...plus he went to the store 2 times to buy stuff

the under hood harness was worse..he rebuilt most of it....we had probs with the alternator but he fixed that too..plumbed the whole fuel system that he scratched built and programmed the computer, and it took the whole day..about 8 hrs...and he did it for free..

there where small issues here and there and he dealt with it all..we drank beer and watched TV while he made the stuff..i dont think i could do it that faster..nor would i try...

i was in the way more than a help, and realize its above my pay scale...went well i thought...he may be an idiot but hes my idiot...

hope this straightens out the miscommunication on my part...i was dead tired when i typed it..and was just doing an general run down..didnt know it was a test..iwould have studied more better

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Old September 12th, 2016, 04:14 PM
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Ok whatever. It seems you have a tendency of not giving the full story then, just like on the Torker thread. From now on I'll keep that in mind, thank you.

But for the record if he has more than an hour in the tuning from here, thank him for his work and go find another tuner.

Last edited by cutlassefi; September 12th, 2016 at 04:18 PM.
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Old September 12th, 2016, 04:30 PM
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i know..imma mess..but what can i say..
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Old October 25th, 2016, 10:00 AM
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Well, hows there over a month since previous update..?
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Old October 29th, 2016, 12:38 PM
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Pics? Anything?
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Old November 10th, 2016, 10:43 PM
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Was this all just talk about someones dreams?
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Old November 11th, 2016, 06:27 PM
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havent had the time to mess with it in a month..sema..travel...work..all got in the way..after the holidays i will get back on it
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Old November 11th, 2016, 11:10 PM
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Okay. Thanks for clarification- was wondering was this one burdened underground or.
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Old March 19th, 2018, 11:30 AM
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Originally Posted by marxjunk
I want a torque monster...talk me out of it...if you can...id like to hear what others have done..if any..i cant find a post anywhere on one..

low boost...DIY/junkyard build....i think the 403 is a good start..low comp....big cubes...and cheap....not a racer...a peppy street car...nice manners...and a tire shredder...i have a $200 runner...and a ton of olds stuff laying around.... after arguing with a couple friends...we have a challenge...and i want to do it...because they say i cant, lol..you know...a challenge...i need a good challenge...low boost..so no high end stuff...i understand the forged requirments etc..but if it pops..it pops..hence low boost...

Im doing a 403...they are doing a 383 mopar junker..lol...i torture them about junk mopars....s'all in good fun
Many years ago there was a car magazine article that featured exactly what you're talking about. They took two Firebirds. A 79 Trans Am with a 403 and a 79 Firebird formula with a 403. A company called Bilmar Automotive out of somewhere in Indiana did the work. I believe that used an AIR research t04 turbo charger but I'm doing this from memory almost 30 years ago so bear with me. They cut a hole in the top of the exhaust manifold on the passenger side of the engine. They ran the Crosse pipe from the driver's side exhaust manifold Outlet under the engine to the what would normally be the outlet on the passenger side manifold. They then welded a 3" dia pipe going straight up from the hole in the passenger side exhaust manifold. The top of that pipe was cut off at a 45 degree angle and a flange that would mate to the turbine Inlet was welded to the pipe. The outlet from the compressor was plugged into the top of the intake manifold where the four-barrel carburetor normally sat. The inlet to the compressor was positiond such that the bowl to hold the carburetor was directly centered over the engine and slightly in front of where the normal carburetor position was. It was also raised up slightly necessitating a low profile air filter. The shaker from the shaker hood was bolted directly to the underside of the hood in the case of the Trans Am in provided some extra clearance for the low profile air filter. Normally the rules of doing turbocharger plumming state that you must have very smooth gas flow from the exhaust manifolds to the turbine Inlet. That sharp bend right where the turbine inlet bolted to the vertical pipe broke those rules. What they discovered was something unique. That sharp bend created turbulence in the exhaust flow entering the turbine. That turbulence turned the turbine almost immediately resulting in practically zero boost lag! They set the wastegate that was apparently integral to the turbocharger at 7 PSI. Effectively upping normal atmospheric pressure by 50% therefore enhancing horsepower by 50%. Since the stock engine featured 7 to 1 compression ratios they figured seven pounds of boost was perfectly safe. Prior to installation that had Dyno Tuned both engines the Trans Am featured gearing of 3.04 in the best they could do was a 16.5 second quarter mile time. After installation the turbocharger that dropped by over 4 seconds! For many years I've tried to find an archive of that particular article but I cannot remember which car magazine it came out of. I think it may have been Car and Driver . I've also tried to locate Bilmar Automotive in Indiana with no luck. But I hope this information helps you in your quest to build one of these awesome machines based on the Oldsmobile 403.
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