Full-Size Chevy

airdeano · 02-17-2005, 10:28 AM

i just got done doing a flow rating on a GM TBI for:
4.3 - 5.0 - 5.7L TBI applications
the blue line represents a throttle body in full trim (injectors, injector
pod) no air cleaner.
the red line represents a throttle body in full trim with and injector pod
spacer installed (injectors, injector spacer and injector pod) no air cleaner.
the green line represents a throttle body with nothing installed.
the column on the left is air-flow in cubic feet per minute
the row underneath the graph is throttle position rated in volts from
a stock TPS.
the test was run with 1000cfm @ 28.00" temp 68.5°

making a big-block TBI fixture and will compare flow rates.
airdeano

96ImpSS · 02-17-2005, 11:02 AM

Quote:

Originally Posted by airdeano

....
the test was run with 1000cfm @ 28.00" temp 68.5°
....

I don't understand what the 1000 cfm signifies. Does this mean you didn't maintain the 28.00" pressure drop to measure the flow at the various TPS positions?

BobMs89shorty · 02-17-2005, 11:29 AM

After all the smack I've read about the TBI, I am surprised. It's not that bad. It's peaking close to 600cfm stock, Alot of cars run 600cfm carbs and pull decent HP numbers.

Greenbuggy · 02-17-2005, 12:07 PM

the 454 tbi (stock) should flow about 670 CFM in full trim, and they certainly aren't hard to port/shave/smooth out for more flow

airdeano · 02-17-2005, 01:40 PM

Quote:

Originally Posted by 96ImpSS

I don't understand what the 1000 cfm signifies. Does this mean you didn't maintain the 28.00" pressure drop to measure the flow at the various TPS positions?

the superflow 1020 applied a 1000cfm constant showing the differential.
airdeano

airdeano · 02-17-2005, 01:41 PM

Quote:

Originally Posted by BobMs89shorty

After all the smack I've read about the TBI, I am surprised. It's not that bad. It's peaking close to 600cfm stock, Alot of cars run 600cfm carbs and pull decent HP numbers.

but you also have to understand that fuel is introduced at the bore
level displacing air flow and volume. this was a dry test.
airdeano

NorCal_z71 · 02-17-2005, 01:42 PM

deano, was that a ported and polish TB, or a stock unit? very interesting too see, thanks

airdeano · 02-17-2005, 01:43 PM

Quote:

Originally Posted by Greenbuggy

the 454 tbi (stock) should flow about 670 CFM in full trim, and they certainly aren't hard to port/shave/smooth out for more flow

and they already incorporate a 3/16" plastic pod spacer, too.
airdeano

airdeano · 02-17-2005, 01:44 PM

Quote:

Originally Posted by NorCal_z71

deano, was that a ported and polish TB, or a stock unit? very interesting too see, thanks

bone stock....
i plan to "remove and radius the ridge to find flow differences.
airdeano

Boosted-Z71 · 02-17-2005, 02:10 PM

I did the remove ridge & radius trick on my 87 TBI and the SOP feel was the difference between night & day. I also ground the throttle shafts & polished / smoothed everything in the air path, along with a thick inj pod spacer.

Good test Dean, cant wait to see the results on the modded TBI

Boosted

oldred95 · 02-17-2005, 04:14 PM

Thats pretty good numbers for a stock TBI. Is there any way you can do a wet test? It would be interesting to see just how much volume the fuel takes up, but I can't believe it would be all that much. Good info.

vhato · 02-17-2005, 05:02 PM

You are the man Deano. I am with Bob..Those are GREAT #'s and proves the spacers do work with TBI's.

TITANIUM · 02-17-2005, 05:54 PM

Great info. The green is the best out of all of them huh. Completely stock. interesting. Would you have actual numbers?

TITANIUM · 02-17-2005, 05:57 PM

So one could safely say that the TBI unit is 600 cfm?

oldred95 · 02-17-2005, 06:18 PM

Quote:

Originally Posted by TITANIUM

So one could safely say that the TBI unit is 600 cfm?

That is dry CFM. I am curious to see how much shaving the throttle shaft helps because if you've ever taken a look at it, that thing is huge, way bigger then it needs to be. After the mods to the TB I would bet it would flow well over 500 wet but I'm just guessing.

TITANIUM · 02-17-2005, 06:20 PM

What is the difference between wet and dry?

oldred95 · 02-17-2005, 06:24 PM

Quote:

Originally Posted by TITANIUM

What is the difference between wet and dry?

Dry means the test is done without injector operation. Basically the injectors do not pulse and no fuel enters the TB. You may not think it would but the fuel actually displaces a fair size amount of CFM's which in turn decreases the number of CFM's of air that can be taken in.

Wet means the test is done with functioning injectors so that gas is figured into the CFM flow rate. Thats not very clear but I'm in a hurry. Hopefully you can get an understanding from it.

TITANIUM · 02-17-2005, 06:29 PM

Quote:

Originally Posted by oldred95

Dry means the test is done without injector operation. Basically the injectors do not pulse and no fuel enters the TB. You may not think it would but the fuel actually displaces a fair size amount of CFM's which in turn decreases the number of CFM's of air that can be taken in.

Wet means the test is done with functioning injectors so that gas is figured into the CFM flow rate. Thats not very clear but I'm in a hurry. Hopefully you can get an understanding from it.

Very well said. I understand now.

Thanks

Old88 · 02-17-2005, 08:04 PM

Quote:

Originally Posted by TITANIUM

Great info. The green is the best out of all of them huh. Completely stock. interesting. Would you have actual numbers?

green = No injectors/pod

the other runs have the pod installed

oldred95 · 02-17-2005, 09:32 PM

Just curious as to whether anyone on the boards has ever made one of these . I wonder what kind of wet CFM's it would flow.

02-17-2005, 11:29 AM	#3
BobMs89shorty Proud to be an Idiot Status: Offline Join Date: Nov 2003 Member ID: 9941 Pics: My Gallery Location: Lebanon, IN Age: 32 Posts: 2,686	Re: TBI AirFlow After all the smack I've read about the TBI, I am surprised. It's not that bad. It's peaking close to 600cfm stock, Alot of cars run 600cfm carbs and pull decent HP numbers. *Founding member of the Indiana Chapter of the Teeny Weeny Club for Secure Adult Males*

02-17-2005, 12:07 PM	#4
Greenbuggy Registered User Status: Offline Join Date: Aug 2004 Member ID: 17773 Pics: My Gallery Location: Delano, Minnesota (or Ames, IA for school) Age: 23 Posts: 202	Re: TBI AirFlow the 454 tbi (stock) should flow about 670 CFM in full trim, and they certainly aren't hard to port/shave/smooth out for more flow Www.speedyoldtruck.com <--Check it out, register for the forums if you've got an OLD truck! '71 K5 4x4, 92 Maxima, '60 Chev C60, '59 VW Buggy

02-17-2005, 01:42 PM	#7
NorCal_z71 formerly 9in4x4 Status: Offline Join Date: Mar 2002 Member ID: 1346 Pics: My Gallery Location: Cali Age: 22 Posts: 3,017	Re: TBI AirFlow deano, was that a ported and polish TB, or a stock unit? very interesting too see, thanks

02-17-2005, 02:10 PM	#10
Boosted-Z71 This is All You'll See Status: Offline Join Date: Mar 2002 Member ID: 1342 Pics: My Gallery Location: Greentown, Indiana Age: 46 Posts: 1,036	Re: TBI AirFlow I did the remove ridge & radius trick on my 87 TBI and the SOP feel was the difference between night & day. I also ground the throttle shafts & polished / smoothed everything in the air path, along with a thick inj pod spacer. Good test Dean, cant wait to see the results on the modded TBI Boosted 98 Ext Cab Chevy-Z71, 5.7, Built Front to Back. 87 SB 5.7 Vortec / TBi Combo, Getting Faster Everyday

02-17-2005, 04:14 PM	#11
oldred95 needs to get a life Status: Offline Join Date: Mar 2004 Member ID: 13448 Pics: My Gallery Location: Live in Enid, OK From Kiowa, KS I'm a Jayhawker, not a sooner Age: 20 Posts: 9,114	Re: TBI AirFlow Thats pretty good numbers for a stock TBI. Is there any way you can do a wet test? It would be interesting to see just how much volume the fuel takes up, but I can't believe it would be all that much. Good info. 1995 Silverado - Very torquey, fun to drive (see below) 1999 NBS Silverdo - Torque? Never heard of such a thing.

02-17-2005, 05:02 PM	#12
vhato Registered User Status: Offline Join Date: Sep 2001 Member ID: 152 Pics: My Gallery Location: Prairieville, La. Age: 33 Posts: 3,211	Re: TBI AirFlow You are the man Deano. I am with Bob..Those are GREAT #'s and proves the spacers do work with TBI's. '04 2500HD/6.0/4x4/4L80-E/4.10/G80/10.5" FF/285-75 BFG AT KO/9200GVW "Show the $5.......give the $1"

02-17-2005, 05:54 PM	#13
TITANIUM Do it yourself member Status: Offline Join Date: Apr 2004 Member ID: 14434 Pics: My Gallery Location: Texas Age: 34 Posts: 3,563	Re: TBI AirFlow Great info. The green is the best out of all of them huh. Completely stock. interesting. Would you have actual numbers? 1991 C1500 Ext. Full Roller 5.7 TBI with too much to list.

02-17-2005, 05:57 PM	#14
TITANIUM Do it yourself member Status: Offline Join Date: Apr 2004 Member ID: 14434 Pics: My Gallery Location: Texas Age: 34 Posts: 3,563	Re: TBI AirFlow So one could safely say that the TBI unit is 600 cfm? 1991 C1500 Ext. Full Roller 5.7 TBI with too much to list.

02-17-2005, 06:20 PM	#16
TITANIUM Do it yourself member Status: Offline Join Date: Apr 2004 Member ID: 14434 Pics: My Gallery Location: Texas Age: 34 Posts: 3,563	Re: TBI AirFlow What is the difference between wet and dry? 1991 C1500 Ext. Full Roller 5.7 TBI with too much to list.

02-17-2005, 09:32 PM	#20
oldred95 needs to get a life Status: Offline Join Date: Mar 2004 Member ID: 13448 Pics: My Gallery Location: Live in Enid, OK From Kiowa, KS I'm a Jayhawker, not a sooner Age: 20 Posts: 9,114	Re: TBI AirFlow Just curious as to whether anyone on the boards has ever made one of these . I wonder what kind of wet CFM's it would flow. 1995 Silverado - Very torquey, fun to drive (see below) 1999 NBS Silverdo - Torque? Never heard of such a thing.

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