383 Vortec questions!!

[Skip Fix]

I just received a Blueprint Engines 383 and their dyno sheet was 396HP using a stock intake but long tube headers on the dyno. It does have their alumnun heads and a slightly bigger cam than the factory L31 that the GM 383 crate motor uses.

 

[L31MaxExpress]

I just received a Blueprint Engines 383 and their dyno sheet was 396HP using a stock intake but long tube headers on the dyno. It does have their alumnun heads and a slightly bigger cam than the factory L31 that the GM 383 crate motor uses.

The GM 383 does not use a factory L31 truck cam.

I doubt they ran it with the stock intake and EFI on the dyno.

 

[L31MaxExpress]

The stock intake can work quite well if it is ported and has enough injector for the combo. Mine has a 48 lb/hr spider.

This was a first fireup, stock tune save for injector flow rate, engine displacement and a Lingenfelter 4" MAF table thrown in it. Torque management was retarding the timing everytime I even touched the throttle.

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This was after connecting the exhaust, 3" cutouts open though and a little tuning. 383 is a great engine although had it fit I would have put a cammed 8.1 instead.

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[Gebo44]

Calling @L31MaxExpress
He's had great success upgrading the GenI small block and using the existing vortec electronics.
What you want to do is possible and people have done it many times over. I would discourage you from removing the fuel injection in favor of a carburetor. Carbs have their place, but cannot compare with the driveability of a properly tuned efi. If the intended purpose of your Tahoe is daily driver, don't ditch the efi.
Lastly, just to level set your expectations, a naturally aspirated gas motor at 383 displacement will never match the torque output of a turbo diesel at 2500 rpm. It will have more usable rpm, though.
If you still want to pursue a 383, go find some of L31MaxExpess posts about his build with the search function. His rig is very similar to what you describe as your vision for the Tahoe.

Thanks for the info and link to L31 MaxExpress.

 

[Gebo44]

I just received a Blueprint Engines 383 and their dyno sheet was 396HP using a stock intake but long tube headers on the dyno. It does have their alumnun heads and a slightly bigger cam than the factory L31 that the GM 383 crate motor uses.

I get it. I was looking at different build companies and was thinking of something along these lines. Westcoast has a good looking 454 as well.

 

[Gebo44]

The stock intake can work quite well if it is ported and has enough injector for the combo. Mine has a 48 lb/hr spider.

This was a first fireup, stock tune save for injector flow rate, engine displacement and a Lingenfelter 4" MAF table thrown in it. Torque management was retarding the timing everytime I even touched the throttle.

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This was after connecting the exhaust, 3" cutouts open though and a little tuning. 383 is a great engine although had it fit I would have put a cammed 8.1 instead.

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Thanks, thats good stuff! My biggest thing is I just don’t have the computer and the knowledge to mess with all that. I’d have to be paying someone all the time to handle it after initial install. I grew up racing circle track in west Texas and teardowns, rebuilds and carb stuff is where I have experience and know-how! I know she isn’t a worthy excuse, but Im 44 and just grew up with 4-barrel carbs. This sensor stuff and fuel injection just throws me. There is just too much it seems in the replacement area and future problems! If I go 383.., it will fit the present motor mounts, and if I go TH 400 all I have to do is unbolt, move the trans mount bracket and drill new holes.., right? Along with driveline. Do you know of any other things besides different ecm I’d run into!? Besides regearing. I’m thinking I’d have to modify the firewall as well.

 

[PlayingWithTBI]

Im 44 and just grew up with 4-barrel carbs.

I grew up with carbs, tri-power, dual point dizzies, etc Decided to learn how to tune/troubleshoot EFI about 5 year ago - I'll be 69 in August, my son will be 40 next year

You're not too old to learn new tricks, only dogs are

 

[Gebo44]

I grew up with carbs, tri-power, dual point dizzies, etc Decided to learn how to tune/troubleshoot EFI about 5 year ago - I'll be 69 in August, my son will be 40 next year

You're not too old to learn new tricks, only dogs are

Yeah.., I hear your point. I’ve just decided to go with the old! Get rid of this spider injection and 100 sensors and just go back to the way it use to be. If I can’t stab a distributor, hit it with a timing light and call it good somethings wrong! Adjust some floats on that carb, hit the air fuel mixture screws and we’re done!!!!
I built a 350 a few years ago that would SMOKE these 35s until I let off the pedal! I just wonder where those days went.!? I suppose I just have to get back to those kind of motors. I had a 390FE my dad built in a 76 F150 in high school. We lived in Colorado.., above 10,000ft with a holley carb. Those bowls gave me no problems. The Truck had a 10in lift, 40s and would burn up those trails. I appreciate the input here. I’ve came to the conclusion on the Internet for a few days now looking at everything and reading all about it that I’m just not that interested in the computer end of keeping all this synced and tuned. Especially where there are a ton of sensors and correlation issues that tend to be common place! The old ways had None of that. And if a man is going to spend more thousands on this thing, he might as well give himself and his pocket book a rest in the future by going backwards Now! And I’d still end up with more displacement and HP the other way. That…, and it looks better under the hood without all that wire mess!

 

[L31MaxExpress]

Yeah.., I hear your point. I’ve just decided to go with the old! Get rid of this spider injection and 100 sensors and just go back to the way it use to be. If I can’t stab a distributor, hit it with a timing light and call it good somethings wrong! Adjust some floats on that carb, hit the air fuel mixture screws and we’re done!!!!
I built a 350 a few years ago that would SMOKE these 35s until I let off the pedal! I just wonder where those days went.!? I suppose I just have to get back to those kind of motors. I had a 390FE my dad built in a 76 F150 in high school. We lived in Colorado.., above 10,000ft with a holley carb. Those bowls gave me no problems. The Truck had a 10in lift, 40s and would burn up those trails. I appreciate the input here. I’ve came to the conclusion on the Internet for a few days now looking at everything and reading all about it that I’m just not that interested in the computer end of keeping all this synced and tuned. Especially where there are a ton of sensors and correlation issues that tend to be common place! The old ways had None of that. And if a man is going to spend more thousands on this thing, he might as well give himself and his pocket book a rest in the future by going backwards Now! And I’d still end up with more displacement and HP the other way. That…, and it looks better under the hood without all that wire mess!

The EFI has better reliability and overall performance. I too have done the carb swap as an expirement. Ran well and got good mileage. In the end went back to the EFI. HP Tuners and a decent laptop was a modest investment but the PCM has near infinite adjustment. Fueling, Timing, Idle, Shift Points, Line pressure are only scratching the surface to the possible adjustments.

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[L31MaxExpress]

The 383 ran well with a carb and HEI. It runs equally well with the OEM style injection. Q-jet was completely refurbished and totally recalibrated for the 383s specs by me. Not a single passageway inside was stock dimension.

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