Baron

Okay, I've heard two different things:

1. The Edelbrock TBI headers are just right for our cars, fit nicely, and once coated by jet-hot, no problems. Flows great. The TPI headers are simply too big and unnecessary, and cause loss of low-end torque, which is half the fun.

2. The Edelbrock TPI headers are the way to go. They work just as well, maybe a bit better, as the TBI headers, fit just as well, and allow for a 350 later on down the road.

WHAT is the TRUTH? Please respond if you have tried both and hence have real experience...I really want to know the truth...and what's with scavenging? What is it and how does it affect flow, etc? Thanks in advance...

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'89 RS LO3- 140,000 miles
14x3 K&N Open Element
Ram Heavy Duty clutch (yes, I think it's great)
Dual .50 caliber machine guns just under ground effects

Coming very soon:
Edelbrock TES (Jet-hot coated)
Catco cat
Edelbrock 3" Cat-back
KYB shocks
Edelbrock Strut Tower Brace
South Side Machine subframe connectors

When your buddy reaches for a 10-pound sledge and says "I think we're gonna have to modify the floor pan, okay?" the answer is NO.

NJ SPEEDER

version 1 of what you heard is completely wrong. the only difference in the headers they sell for 305tpi vs 305 tbi is the collector size on the y-pipe, they just make them to match up to the cat. the primary tubes and the ypipe itself are otherwise exactly the same.
if our cars couldn't handle low back pressure mine would hardly run, i have tes headers for tpi, no cat, and a borla adjustable with the open plate in it, i may as well be running a long straight pipe for all the back pressure i have.

lata
tim

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91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

JPrevost

NJ is right on. If you have a 3" aftermarket cat then you need to ask them what there collector size is and what kind of hook up it is (slip on or not). Only difference in headers are material, primaries, 4-1 or 4-2-1 (aka tri-y headers). I have the tri-y headers from SLP and I hope they work well with the 330hp vortec headed engine I'm getting.

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, Jon (91 RS too many mods to list), getting new engine in summer

Scott C

I have first hand experience. Number 2 is the way to go. Night and day difference.

Z28 Boy

I definitely agree...I think that the headers themselves are the same thing (except for the little "tag" edelbrock puts on them for that CARB crap). The difference is only in the collector. Go with the TPI ones (I think they were model #6872????).

I actually ditched them for a set of SLP stanless ones, with out teh AIR tubes. But, the Edelbrocks were really easy to install.

Just make sure that you get them coated as soon as you can afford it because they will look like total poop after a few miles.

-Brian

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1991 Camaro RS - Ultra Blue Metallic, T-Tops
----------------------------------------------
GM 350 HO Crate Engine - Vortec Heads, Edelbrock Performer Vortec Intake, Holley 670 CFM Throttle Body, Open Air Cleaner w/14"x3" K&N, SLP 1 3/4" Stainless Headers, Edelbrock Victor Series Water Pump, MSD 6AL, Blaster Coil, 8.5mm Super Conductors, Accel Cap and Rotor, Hypertech Fan Switch & Thermomaster Chip, AC Delco Rapidfires, 3" Cat Back, Flowmaster 40 Series Muffler
700R4 - 2,400 Stall Converter, Vette Servo, Shift Kit, B&M Super Cooler
GM 10 Bolt -coming soon Auburn Pro Series Differential, Richmond 3.73s
Brian's 1991 RS Central NY F-Body Association
Join the Third Generation F-Body TBI Web Ring
z28boy@twcny.rr.com IM name: Z28 Boy

Baron

Just for the record...the TBI ones have 1 5/8" primaries, while the TPI ones have 1 3/4" primaries...and I believe that, along with 2.25" vs. 3" collector size, are the only differences...does ANYBODY think the TBI ones are the way to go, or is the whole planet unanimous in saying TPI?

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'89 RS LO3- 140,000 miles
14x3 K&N Open Element
Ram Heavy Duty clutch (yes, I think it's great)
Dual .50 caliber machine guns just under ground effects

Coming very soon:
Edelbrock TES (Jet-hot coated)
Catco cat
Edelbrock 3" Cat-back
KYB shocks
Edelbrock Strut Tower Brace
South Side Machine subframe connectors

When your buddy reaches for a 10-pound sledge and says "I think we're gonna have to modify the floor pan, okay?" the answer is NO.

Dan W

I'm running Edelbrock TPI headers on my TBI T/A... These headers have a 3" collector for single cat. The primaries are mixed 1 1/2" and 1 5/8"... not 1 3/4. Measured this myself with my micrometer. And no, they are not some kind of mistake... I purchased these new and there are others on here who have gotten the same measurement. The only other difference is between the two kits is that TPI headers lack the heat stove on the drivers side header.



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1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Comp Cams roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

Zac's92

The edlbrock tes for 305-350 TPI have 1 5/8" primaries just like the TBI ones. You are correct about the colector size. I think SLP sell 1 3/4" primary headers for 350+" engines.
Zac Spalding

Dan W

I say again, the edelbrock headers use mixed primaries. Some are 1 1/2" others are 1 5/8" If you are actually running these go out and measure and you will see.

91Bird305

What would be the performance difference in my 305 if I have the 1-1/2" instead of the 1-5/8" and vice versa?

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Eric Natzke
91 Firebird 305 TBI

ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-160 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone-Free TBI mods
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html

Kevin91Z

iTrader: (1)

Go read some of the Edelbrock vs SLP threads on the Exhaust board. Your exhaust valve is 1.5", why wouldnt you want your headers to be larger, so the hot exhaust gas can expand and exit easier? On TES headers, the #3, 5, 4, and 6 primaries are 1.5", while the #1, 7, 2, and 8 are 1.625". Plus there is weld inside the header ports, making them even smaller. On the SLP 1 5/8" headers, all primaries are 1 5/8", and there is no weld inside the port openings. I think Edelbrock designed their headers for 305's in the early 80's, and didnt want to redo it for 350's. SLP started in 87 or 88, after the 350's came out, and so designed both sizes of headers, 1 5/8" and 1 3/4".

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

Dan W

I dont remember anything about welds protruding into the exhaust ports on my edelbrocks. The air tubes do protrude about 1/4" or so into the ports... I cleaned them up with a dremmel.

The Edlebrocks in my book are probably a better piece for a mild motor. The whole dual sized primary thing I beleive is to make a shorty header into a tuned header... like a long tube or equal length. Still that 1 1/2" primary is going to become a restriction at some point... probably when you get to the 300 hp range. I'd go with the edelbrock units if you plan on keeping the 305. If you plan on upgrading to a larger motor and installing aftermarket heads, etc. then I'd go with the 1 3/4 slp's. The difference of installing any of these headers on your car will yeild good gains but I would bet money that you couldnt FEEL the difference between the edelbrock and the slp on your 305.

In the end, I beleive you should make a plan for your car and use parts that fit the overall package in the long term. If that package includes a 400+ horse 383 with Air Flow Research heads then your in 1 3/4 header teritory.

Mongoose

iTrader: (2)

I also have first hand experience with both sets of headers on my Formula. The 6872 TPI set is the better of the two. As for the heat stove,if you have an open element you won't need it anyway. Only problem concerns the Y pipe. If you're running SSM subframe connectors the 3" section that connects the cat will make contact with the SFC. Choices are to notch the SFC to allow clearance or "modify" the pipe. I've also done both with 2 seperate Y pipes. Go with the notched SFC-much better results.

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Mongoose-NCTGA-1990 Pontiac Formula/305 TBI-700R4 with Edelbrock Performer TBI intake,TES headers,and STB,K&N,MSD-6AL,Holley laser shot coil,Accel Extreme 9000 wires,Jet Stage 2 chip,TCI shift kit with corvette servo,Richmond 3.73 gear with Auburn 3 series posi,no cat,SLP 3" cat back,Eibach sportline springs,Energy Suspension poly throughout,Lakewood LCA and adjustable panhard bar package,SSM subframe connectors,IROC wonder bar,Tokico 5 way adjustable struts and shocks,Autometer electric fuel pressure gauge,Alpine,JL Audio,MB Quart,92 GTA taillights,92 GTA aero wing and hatch,Steve Spohn LCA relocater kit,MacEwen White face gauges,84 T/A cold air induction air cleaner,Grant Formula GT wheel.

Baron

Thanks for all your responses, everyone...Summit is shipping my TPI headers to Jet-Hot as I type...it's been super-helpful to get your input, as otherwise I would have even less idea of what I'm talking about than I do now...but that's the purpose of the board now, isn't it? Mongoose, thanks for that heads-up on the SSM SFC's...I really appreciate it!

------------------
'89 RS LO3- 140,000 miles
14x3 K&N Open Element
Ram Heavy Duty clutch (yes, I think it's great)
Dual .50 caliber machine guns just under ground effects

Coming very soon:
Edelbrock TES (Jet-hot coated)
Catco cat
Edelbrock 3" Cat-back
KYB shocks
Edelbrock Strut Tower Brace
South Side Machine subframe connectors

When your buddy reaches for a 10-pound sledge and says "I think we're gonna have to modify the floor pan, okay?" the answer is NO.