L31 Extreme Budget Build

[Scooterwrench]

How large is the snorkel on that lack of air breather?

 

[L31MaxExpress]

How large is the snorkel on that lack of air breather?

Same as a 4.3 or SBC TBI truck, 5.5 x 2.5. By comparison the big block one is 8 x 3.5.

Edit, I just corrected it with the actual dimensions of both. The elbow through the core support is 6 x 3" and the SBC intake duct narrows substantially after the elbow. The big block duct is just proving to be harder to find than hens teeth. Big block uses a much larger filter and housing as well.

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[Scooterwrench]

Same as a 4.3 or SBC TBI truck, like 2 x 3. By comparison the big block one is 8 x 3.5.

Yeah,I can see where that would be starving it for air. Does yours have that intake muffler thing on there?

 

[L31MaxExpress]

Yeah,I can see where that would be starving it for air. Does yours have that intake muffler thing on there?

Luckily it does not and I pulled the semi circular baffle and the thermac flap out of the air cleaner. Under ~4,000 rpm the TBI SBC air cleaner is not too restrictive though, under 1 in/hg loss. Above 4,000 it starts building vacuum quickly. No surprise though, it was engineered for a 350 that only turned ~4,000 rpm and made much less power.

 

[Scooterwrench]

Luckily it does not and I pulled the semi circular baffle and the thermac flap out of the air cleaner.

Did you cap the inlet for the heat riser hose? Even with the diverter flap out it will pull underhood hot air through that hole.

 

[PlayingWithTBI]

On a TBI it's not just the assembly under the hood that's restrictive, it's the ports in the fender and under the headlights.

Here's what's inside the fender.

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Under the headlights and behind the Parking/Turn Signal housing...

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Maybe it's good enough for a stock 5.7L but, not for a higher revving, bigger cube engine.

 

[L31MaxExpress]

Did you cap the inlet for the heat riser hose? Even with the diverter flap out it will pull underhood hot air through that hole.

I temporarily permenately sealed it and the air divert air port with aluminum high heat duct tape used for HVAC stuff.

 

[Scooterwrench]

On a TBI it's not just the assembly under the hood that's restrictive, it's the ports in the fender and under the headlights.

Here's what's inside the fender.

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Under the headlights and behind the Parking/Turn Signal housing...

You must be registered for see images attach

Maybe it's good enough for a stock 5.7L but, not for a higher revving, bigger cube engine.

Yeah,I'm running that rig now but I want to cut two openings in the rad. support,one either side of the rad. and run two 3" hoses to my breather. If I position them right I'll get good ram air. I've got to figure out how to baffle them so I don't get rain injection while keeping airflow.

 

[PlayingWithTBI]

I've got to figure out how to baffle them so I don't get rain injection while keeping airflow.

Hell, water injection makes you go faster

You can install cut-outs that would drain the water between the core support and the engine. You won't have to worry about "Cold Air Induction" when it's raining.

 

[Scooterwrench]

Hell, water injection makes you go faster

You can install cut-outs that would drain the water between the core support and the engine. You won't have to worry about "Cold Air Induction" when it's raining.

Probably easier to put skuppers in my breather.