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

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

Old June 26th, 2016, 05:06 PM
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I want to build a street 403 with a turbocharger..low boost

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

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Old June 26th, 2016, 05:58 PM
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I like the ideal.
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Old June 26th, 2016, 06:33 PM
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I like the idea too. With your car experience and being a pontiac fan, Do you think a 301 turbo set up...or something like that fit the bill?
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Old June 26th, 2016, 06:54 PM
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i'm not sure..i dont think the 301 stuff will feed the 403...its a draw thru, and i want to do a blow thru...i have access to some 301 stuff..but i dont know just yet..been scanning the net all day...and there isnt a bunch of info on a turbo olds out there...

and i have some blow thru stuff already like turbo hat and a GT45 chinese turbo...

there just isnt much out there to know what works and doesnt...

i keep finding a thread about the mondellotwister...but the links dont work...anyone know anything about it?
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Old June 26th, 2016, 06:54 PM
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403

What car is this going in?
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Old June 26th, 2016, 07:42 PM
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...well.....its a firebird...a 70 formula....that was a mild custom built in the 80s...its the only non-air conditioned muscle car i own that i dont have resto plans for....so i dont have to deal with all that..

i want to build a beater type hot rod...back like when i was a broke kid, just trying to get a car together to cruise...

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Old June 26th, 2016, 08:04 PM
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I've got a 355 with a turbo off a gm diesel(Borg Warner gm-8) they are cheap around here and guys always pull them off for a bigger turbo. Car is a street car built for autocross so I sized the turbo small so it would spool quick. Really fun on the street and the 275 series tires won't even try to hook up
0ACED5B0-DDF3-4C9F-B5D3-EDBFE59C42E3_zpsmajxcw0o.jpg
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Old June 26th, 2016, 08:05 PM
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Find some BBO heads and a Performer RPM. The factory SBO heads choke a 403, even with boost. Even J heads are an improvement for sure. You only thing is you'll need to open up the head bolt holes to " on those.
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Old June 26th, 2016, 08:06 PM
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Originally Posted by young olds View Post
I've got a 355 with a turbo off a gm diesel(Borg Warner gm-8) they are cheap around here and guys always pull them off for a bigger turbo. Car is a street car built for autocross so I sized the turbo small so it would spool quick. Really fun on the street and the 275 series tires won't even try to hook up
That is awesome!!!
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Old June 26th, 2016, 08:16 PM
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If your just trying to prove something go draw through, it's cheaper. With blow through you will have to mod the carb, run an adjustable fuel pressure regulator, and a bov. All extra cost on top of draw through. Is grab a quadrajet mount from a 301 or early turbo Buick and run it in front of whatever turbo you want
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Old June 26th, 2016, 08:17 PM
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Originally Posted by svnt442 View Post
That is awesome!!!


Thanks
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Old June 26th, 2016, 10:17 PM
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i already own a hat, a blow thru carb...prob 3/4s of a fuel system etc...ive built a few turbo LS1s...just want something diff...

id use a paxton box before id use a draw thru system..but thats just my decision..no real hate on the draw thru...i just want to see what other people have done or used...get a plan..

ive owned a few old turbo-sonic draw thrus for SBCs from the 80s..etc..and a couple martin systems too...they work..but blow thru or a pressure box is what i am leaning towards..ive evn worked on a couple supercharged Studes and a supercharged Packard Hawk...all way back when..

Young...why the Q-jet? pretty uncommon choice...something i'd do...
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Old June 27th, 2016, 07:56 AM
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The simple answer is I like quadrajets. Looks like blow through is in your future.
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Old June 30th, 2016, 04:08 PM
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IMO, the 403 is the worst platform to choose for this project. Thin Siamesed cylinders are prone to detonation on N/A engines, much less a boosted application. Big heavy pistons in a webbed block, not a great combination. Tight bore spacing could result in head gasket issues under the extra pressure. Better to go with a 350, sacrifice the cubes for durability. Add more boost to make up for the loss in cubes and you are waaaaaay ahead of the game. Again, IMHO.
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Old June 30th, 2016, 04:17 PM
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Originally Posted by captjim View Post
IMO, the 403 is the worst platform to choose for this project. Thin Siamesed cylinders are prone to detonation on N/A engines, much less a boosted application. Big heavy pistons in a webbed block, not a great combination. Tight bore spacing could result in head gasket issues under the extra pressure. Better to go with a 350, sacrifice the cubes for durability. Add more boost to make up for the loss in cubes and you are waaaaaay ahead of the game. Again, IMHO.
He said he likes a challenge and if it pops it pops. I also totally agree with you.
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Old June 30th, 2016, 05:25 PM
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Originally Posted by wr1970 View Post
He said he likes a challenge and if it pops it pops. I also totally agree with you.

I never really understood that philosophy. Why do something that you know going in might be a mistake? You could (probably) make a 260 run 12s in a G-body, but why????
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Old July 1st, 2016, 10:46 AM
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Originally Posted by captjim View Post
I never really understood that philosophy. Why do something that you know going in might be a mistake? You could (probably) make a 260 run 12s in a G-body, but why????

why ask why? the way you feel about me doing it, is exactly the way i feel about you p!ssing on my parade..
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Old July 1st, 2016, 12:15 PM
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I want you to do it, who cares if it breaks. I kinda want mine to, in time, then I can build sometging stronger.
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Old July 1st, 2016, 12:37 PM
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Originally Posted by young olds View Post
I've got a 355 with a turbo off a gm diesel(Borg Warner gm-8) they are cheap around here and guys always pull them off for a bigger turbo.
Definitely check this out. Turbos for diesels are plentiful.
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Old July 1st, 2016, 12:55 PM
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Originally Posted by marxjunk View Post
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..

I'm not "pissing on your parade", I am doing what you asked, trying to talk you out of it. You can't find a post about it anywhere because it is a bad idea and nobody else has wanted to waste the time and $ to do something that is so obviously flawed. But, go ahead and have at it, most of the parts will transfer over to a 350.
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Old July 1st, 2016, 01:30 PM
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ahh..its just money..and what else do i have but time?.i could think of worse things to spend time and blow money on...just sayin'..and i havent blown something up in decades...

so..why not take a pile of junk i have lying around that no one wants to buy...and blow some stuff up for *****-n-giggles????
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Old July 1st, 2016, 02:08 PM
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FWIW, I don't think you would necessarily blow an engine. The 403 does have windowed mains (unless you have one with solid mains from a wagon). Plus, it has Siamese cylinders, but it's an Oldsmobile engine. Just build it right and you should be fine.
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Old July 1st, 2016, 02:13 PM
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im trying to be a realist here..

low rpm....low boost...low cost..street car..not a race car..just a kick in the pants...cant wipe the grin off your face type car...

i want it olds powered..and why not take the red headed step child and see if it can live

im only buying a few things for the motor...an oil pump..cam and lifters and springs..prob a good gasket/overhaul type kit...the rest i am begging...borrowing...and bartering for...this aint a high end..big dollar deal...

i have a bunch of stuff from other builds...prob the most expensive stuff i will have to buy is a fuel system and a single pane intake.....

but i have some friends that race big time...and i will scrounge some fuel stuff that i can from their stash...gonna be lotsa begging and trading...i will make what i can..and trade the labor for the rest..

i have the running 403...a semi built up 350 turbo with a small stall converter...and a couple rears..i will have a plan over this weekend...and im gonna document and video everything i can...

id like to have a low end car i can torture...i was going to put it in my firebird..but the cars worth too much to do that...it needs to stay pontiac powered...like it should be...

i have a rust free 2wd s10 80s blazer needing a motor....and a few a-bodies...too....i'm going to see what comes together the easiest...and slap it together..and try not to buy anything if i dont have to...but no matter what it goes in..its about the 403...not the body

if it works out and is more than i expect...maybe then i will stick it in the firebird or find an X-body of some kind..

Last edited by marxjunk; July 1st, 2016 at 02:25 PM.
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Old July 1st, 2016, 04:50 PM
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Originally Posted by Olds64 View Post
FWIW, I don't think you would necessarily blow an engine. The 403 does have windowed mains (unless you have one with solid mains from a wagon). Plus, it has Siamese cylinders, but it's an Oldsmobile engine. Just build it right and you should be fine.

The Siamesed cylinders are more of an issue, IMO, than the windowed block. 403s tend to have detonation and overheating problems because of them. Adding boost adds cylinder pressure which only increases the chances of detonation.

I'm all for Olds-powered and I thing a low buck turbo project is a cool idea, just use a 350. The advantages so outweigh the negative, the onlky one being less cubes.

Find a 350 with 14CC pistons, easy enough. Bolt on some BB heads to lower compression and add flow, spool it up and let 'er rip.
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Old July 1st, 2016, 07:55 PM
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If your going to run low boost I wouldn't run too low of a comp ratio. I'm running just over 9:1 on my 350 to keep some off boost performance. Car is mostly a street car, well all street so far but will see the track soon enough.
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Old July 1st, 2016, 08:03 PM
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it crossed my mind,,but havent gave it a lot of thought..i think 403s are in the 8 range?...i need to do a little research.. but i have some #5,6 and 7 heads...just havent got that far yet..thanks for the heads up..i read somewhere 5 heads with the 403 valves was a good combo..

i got the motor out and cleaned up today. its on the stand..dug the trans out..

SO IT BEGINS..lol...
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Old July 2nd, 2016, 01:14 AM
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Originally Posted by marxjunk View Post
it crossed my mind,,but havent gave it a lot of thought..i think 403s are in the 8 range?...i need to do a little research.. but i have some #5,6 and 7 heads...just havent got that far yet..thanks for the heads up..i read somewhere 5 heads with the 403 valves was a good combo..

i got the motor out and cleaned up today. its on the stand..dug the trans out..

SO IT BEGINS..lol...
Keep in mind that if you decide to go with any early head be it small or big block, you will need to open up the head bolt holes for " bolts because all of the early blocks used 7/16 bolts.
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Old July 2nd, 2016, 03:31 AM
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Originally Posted by marxjunk View Post
it crossed my mind,,but havent gave it a lot of thought..i think 403s are in the 8 range?...i need to do a little research.. but i have some #5,6 and 7 heads...just havent got that far yet..thanks for the heads up..i read somewhere 5 heads with the 403 valves was a good combo..

i got the motor out and cleaned up today. its on the stand..dug the trans out..

SO IT BEGINS..lol...
403s use a #4A head which gives a cr around 7.8 to 1. Guys use the older 350 heads (#5-#7a) on a 403 to bump the CR up into the 8.5 to 1 range, cheap way to add both compression and flow. Not sure how much boost you are planning, but you don't want the CR to creep up too high.

Last edited by captjim; July 2nd, 2016 at 03:53 AM.
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Old July 2nd, 2016, 03:32 AM
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Originally Posted by young olds View Post
If your going to run low boost I wouldn't run too low of a comp ratio. I'm running just over 9:1 on my 350 to keep some off boost performance. Car is mostly a street car, well all street so far but will see the track soon enough.

I am no expert, but 9 to 1 with iron heads seems a tad high is you are going to add boost to it. Your tune better be dead-nuts.
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Old July 2nd, 2016, 06:56 AM
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i appreciate the help guys..

i am putting a plan together...

i have turbo/tunner buddy thats built more turbo cars than anyone i know..i told him lat night what i wanted to do and hes more excited than me..lol.
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Old July 2nd, 2016, 02:33 PM
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Keep us updated on progress, interested in watching
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Old July 3rd, 2016, 11:12 AM
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Had a 86 T Type and as far CR with boost and iron heads on pump 91-93 back then it was well known that 8.0:1 was stock and not to be increased. You can easily run low boost with that say under 14 psi and the gurus would tune with a very limited timing say maybe 24 total and got away with 20 psi but that is with EFI and knock sensors etc. So I would not deviate from 8:1 and keep max rev at 4800-5000. Heck even the fast GN cars were only revving to 4800 , camming was only 200/200 ish @ 050. Helll just do 8-10# and keep it modest small cam low revs might be fun. If it blows block then swap in a DX. Here is the old T after the guy I sold it to took.it next level. The engine I built did go 114 mph though with Lunati 200 200 cam, home pocket ported stock valve heads.
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Old July 3rd, 2016, 07:29 PM
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I for one wish you a lot of luck. No guts no glorry. Any of the heads you have, 5,6, or 7 should be fine with about the same flow characteristics. Choose the set with the best guides. Stuff in 2.07" intakes and1.71" exhaust valves. Have your machine shop hog out the bowl to utilize the bigger valve. With a boosted application, the exhaust side will be a hinderence. There's a couple ways you can get that exhaust out. Pick a cam specifically designed for the boosted application, with more exhaust duration. you could also utilize 1.7:1 ratio exhaust rockers. Are you going to build your own logs? May want to firm up your chassis choice before you start fabbing up those.
Good luck with your project, Dave - The Freak
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Old July 3rd, 2016, 08:17 PM
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i am doing my own logs...i already have the material, and have built some for a Pontiac in the past..you would be shocked at what you can buy..flanges etc..really a huge selection...

a-body is going to be the easiest...easy and i have ton of stuff already just taking up space..i dont know yet....

theres people pushing some good power on ugly home made logs..they are proven..and for the level i want...they will be fine...i'll wrap them to hide the ugly...some guys are getting way more HP than i even want..im not going all out..i just gotta beat that mopar once...

i dont want to go crazy on spending money....low buck...trade..build..borrow..very little cash is the plan...

i spent the day looking at cams...i havent decided yet...

i think i am going to go with big block heads..i can start with them and be where i would want the SB heads.....not sure yet...more research..ive been reading everything i can find out there.....

i have a friend thats always asking for help..he has serdi equip to work the heads...i will trade labor with him..he keeps asking me to hang 1/4s and wheel housed on his mustang..so i will wear that bridge out...lol

Freak..i saw your write up on the home porting..very good job..way more patience with people than i have..i enjoyed the post..and thanks for the wishes..
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Old July 30th, 2016, 11:40 AM
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things are moving along...i started gathering parts...some i had..some i bought...still working out a few things....but i have a direction...and a plan...so..when i get a little further..i will make a new thread...cheap and almost all GM...

right now i have just about everything and have around $400 cash outlay and need a few other things i just cant get used or to trade for..theres some things i want..and things i want to upgrade and its a struggle to not just buy the stuff or upgrade...but i am talking a low budget build...so...lets see if i can stick with the idea..i'm trying..

so now i am working some bartering deals..a few trades that go good and i'm in a better spot

and unless i stumble in a deal..i estimate another $1000 cash and its running...and most of its fuel system

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Old July 31st, 2016, 05:36 AM
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I really love following along on this thread. Keep up the ideal and make it happen. Thanks for your post.
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Old July 31st, 2016, 10:12 AM
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I know very little about turbos but love them. I will watching this thread as well. I have a 425 Starfire block sitting here on an engine stand with a ton of parts...HMMM 64-F85 with a 425 turbo??
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Old August 19th, 2016, 07:49 AM
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Interesting lol, I was just thinking of trying this with my 403 the other day
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Old August 20th, 2016, 10:45 PM
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GREAT THREAD!!!!! I also know very little about turbo's. But they have become very popular lately, and for good reason. They make really good power rather cheap, or it seems that... Either way I edmire what you are trying to accomplish! You to YOUNG OLDS, i also have read your threads! VERY COOL GUYS!!! Makes people think!

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Old August 22nd, 2016, 08:43 AM
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Originally Posted by cwb442 View Post
GREAT THREAD!!!!! I also know very little about turbo's. But they have become very popular lately, and for good reason. They make really good power rather cheap, or it seems that... Either way I edmire what you are trying to accomplish! You to YOUNG OLDS, i also have read your threads! VERY COOL GUYS!!! Makes people think!
Thanks. Marxjunk how's the project coming?
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