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470 hp Vortec L31 Build-The Complete Saga

Old 01-22-2019, 12:39 AM
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470 hp Vortec L31 Build-The Complete Saga

Alright....Plans have changed, no 305 Firebird build. 305 is too Small It's now an L31 Vortec 350 TBI conversion Firebird build. I have one in my truck that has 40,000 miles on it. Crate GM. Just begging to have a 450/480 cam put in, rollers,Lifters,roller rockers....
Should be around 470 Horse?

The Concerns:
1) I need a rear end. Can I use the one of my 97 Tahoe? If not I need something with a budget in mind. Maybe a quick swap of something else easy to find?

2) Im pulling a 700R4 out of a 92 v6 base bird. First time rebuilding one of these so any guidance on that would be much appreciated. Going to need something upgraded, shift kit? Down the road build im going to be adding power so I want to do it right the first time.

3) I've heard something about swapping torque converters with an s10? Why does this affect things? Can someone explain this a little?

4)My wiring is screwed. Last owner screwed it up bad. I'm piecing in parts of the wiring harness off the 92 v6 as well. Is there anything anyone has done to "upgrade" or "Modernize" the wiring systems? Im going to get pretty far into this because I HATE the electric system on these generation of GM stuff. It sucks. I don't want to deal with this EVER again after this build. Also i'm waterproofing the wires as much as possible because this build is also for the apocalypse. I am obsessed with the mad max stuff.

5) Would it be better to keep the Vortec belt system on it or change it to the 3rg gen TBI set up? Ill Play with this theory in a few days when I'm back on the project and update.

Ill add to this tomorrow cant think of anymore at the moment.
Thanks!

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Old 01-22-2019, 05:48 AM
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Re: 470 hp Vortec L31 Build-The Complete Saga

I’ll just start with the two most obvious things here. You will not be making 470 horsepower on a Vortec 350 with stock heads and the mods you mentioned. 2nd, the rear end out of your Tahoe is too wide to fit in an f-body, nevermind the fact that it has mounting points for leaf springs and no torque arm mount nor LCA bracket mounts.

Last edited by Richardman1992; 01-22-2019 at 02:19 PM.
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Old 01-22-2019, 07:23 AM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Are you talking about this cam?
https://www.summitracing.com/parts/c...make/chevrolet

Either way no chance of 470 hp unless you are spinning the **** out of this motor also while the vortec heads are good they are not meant for high lift or high RPMs

You can go aftermarket stand alone EFI and clean up the wiring a lot

Keep the serpentine belt system.
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Old 01-22-2019, 11:44 AM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Originally Posted by Richardman1992 View Post
Iíll just start with the two most obvious things here. You will not be making 470 horsepower on a Vortec 350 with stock heads and the mods you mentioned. 2nd, the rear end out of your Tahoe is too wide to fit in an f-body, nevermind the fact that it has founding points for leaf springs and no torque arm mount nor LCA bracket mounts.
Well....I didn't say anything about stock heads. I left out a step, take motor out of Tahoe, upgrade everything from the heads up including cam, chain etc, then put it in the Firebird and adapt it to the Holley throttle body. With the rear end I was more thinking using the differential off the tahoe and put it in one of the Firebird axles. Oh ye of little faith......I'm gonna get 470 one way or another
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Old 01-22-2019, 11:47 AM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Yeah thats one of the cams I was looking at. Im not 100% on parts yet Im going to get the L31 out of the truck first and play with it a little. With the EFI believe me Id like to but the budget wont allow it. Maybe next build. So I'm just cleaning up the existing stuff and getting rid of the garbage. Emissions isn't a factor where I live either so quite a bit can go.
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Old 01-22-2019, 11:53 AM
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Re: 470 hp Vortec L31 Build-The Complete Saga

If you want 470 dont bother upgrading vortecs. Time you spend that money to port them could buy a set of budget aluminums

however minor work and valve job on vortecs can get low 400’s to 447 hp if you copy david vizards build
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Old 01-22-2019, 11:57 AM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Originally Posted by Doomsayer88 View Post
Well....I didn't say anything about stock heads. I left out a step, take motor out of Tahoe, upgrade everything from the heads up including cam, chain etc, then put it in the Firebird and adapt it to the Holley throttle body. With the rear end I was more thinking using the differential off the tahoe and put it in one of the Firebird axles. Oh ye of little faith......I'm gonna get 470 one way or another
That way probably wont include that cam without some nitrous. That cam will be closer to 330
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Old 01-22-2019, 02:16 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Originally Posted by Doomsayer88 View Post
Well....I didn't say anything about stock heads. I left out a step, take motor out of Tahoe, upgrade everything from the heads up including cam, chain etc, then put it in the Firebird and adapt it to the Holley throttle body. With the rear end I was more thinking using the differential off the tahoe and put it in one of the Firebird axles. Oh ye of little faith......I'm gonna get 470 one way or another
if by differential, you mean the carrier and ring gear and whatnot, you canít fit a 8.5Ē ring gear (what the Tahoe has) into a 7.5Ē housing (what the bird has).
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Old 01-22-2019, 02:56 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Originally Posted by Doomsayer88
Im pulling a 700R4 out of a 92 v6 base bird. First time rebuilding one of these so any guidance on that would be much appreciated. Going to need something upgraded, shift kit? Down the road build im going to be adding power so I want to do it right the first time. I've heard something about swapping torque converters with an s10? Why does this affect things? Can someone explain this a little?
The 700R4 from the V6 is for a 60 degree engine. Members swap to an S10 converter because the S10 shares the same 60 degree 700R4 transmission but with a higher stall, so it is a cheap and easy upgrade from stock...

- Rob
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Old 01-23-2019, 11:48 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Is David Vizard on the forum?
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Old 01-23-2019, 11:50 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Yeah nitrous is in the plans, any suggestions as far as that goes?
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Old 01-23-2019, 11:51 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

so the converter in the v6 is the same as in the s10?
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Old 01-23-2019, 11:55 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

Originally Posted by Street Lethal View Post
The 700R4 from the V6 is for a 60 degree engine. Members swap to an S10 converter because the S10 shares the same 60 degree 700R4 transmission but with a higher stall, so it is a cheap and easy upgrade from stock...

- Rob
can you explain the 60 degree concept?
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Old 01-24-2019, 12:08 PM
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Re: 470 hp Vortec L31 Build-The Complete Saga

will a V-6 700 even bolt up to a V8? they have different bolt patterns last I looked
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