Restriction of 1 3/4 vs 2 inch headers - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Bildo · 01-02-2019, 08:00 AM

Max effort F1-A 427 ERL Superdeck on E-85 setup making just 800hp with the procharger intake tube on probably around 900rwhp with it off. I have SLP 1 3/4 inch long tubes on car now that seem to be causing a bit of restriction. How much more do you think I would benefit from 2 inch headers?

Juiced1 · 01-02-2019, 08:26 AM

I can't say we've run into to many people making that upgrade. I'd love to see if they are holding you back. I would guess somewhere around 30rwhp or so.

Bildo · 01-02-2019, 09:27 AM

Yeah everything was dropping off early @ like 5400rpm tuner ran into this issue with his F1X vette, says the whole curve should improve with larger headers. Only able to make about 15-16lbs of boost right now with barely over spinning the blower @ 6800rpm. I also need to find some other sort of intake tube I can run on the street as a 100rwhp difference between filter on and off is a bit too much to leave on the table.

UNRIVALED SS · 01-03-2019, 07:00 PM

There is a Vette winning everything here making around 1200-1300 HP in 22 psi through. 1 7/8” headers. Probably 10 hp more or less depending on everything else you have after that

realcanuk · 01-03-2019, 07:27 PM

If anything boost would be higher with a restrictive exhaust. If its not making the boost it should, I would look elsewhere for that problem.

Js2fst · 01-03-2019, 11:53 PM

No you are pushing a line 2" headers will make a huge difference. Look up 1 7/8 headers vs 2" gains

0-120 · 01-04-2019, 01:13 AM

Isn’t there a fitment issue with the larger headers? I thought I read this concern in another topic.

If not, I may consider them

eLeSthree · 01-04-2019, 09:54 AM

Quote:

Originally Posted by 0-120

Isn’t there a fitment issue with the larger headers? I thought I read this concern in another topic.

If not, I may consider them

Texas Speed 2inch header with no cats was my very first modification. The steering column knuckle does tap the header during hard right turns. That might bother some people, but I dont care.

My car is a rebuilt title and its a go fast toy. To each his own.

Someday I may remove the knuckle, and grind it down on the belt sander for clearance.

If I were Bildo, I'd want more airflow, not more boost pressure. I'd upgrade.

realcanuk · 01-04-2019, 12:38 PM

Quote:

Originally Posted by Js2fst

No you are pushing a line 2" headers will make a huge difference. Look up 1 7/8 headers vs 2" gains

From 1 3/4 I would agree. Changing from 1 7/8 to 2 wouldn't be worth it IMO, unless your are really concerned about every last HP. My car makes more than many similar builds, and I have 1 7/8. There are just better ways to spend that money.

SSBUSDRVR · 01-04-2019, 01:43 PM

Quote:

From 1 3/4 I would agree. Changing from 1 7/8 to 2 wouldn't be worth it IMO, unless your are really concerned about every last HP. My car makes more than many similar builds, and I have 1 7/8. There are just better ways to spend that money.

Agree. Bildo you will see more swapping out the 1 3/4. Don't know how much at your level build. Run ARH Ceramic Coated 1 7/8 here. Was going to upgrade to 2inch and was told to save the money at my level.
What Intercooler and Boost are you running? At only 12lbs for now until make E85 switch on the Stage2 D1X.
Making just over that much with the 1300hp Intercooler. Maybe a restriction/ leak around Intercooler area?

UNRIVALED SS · 01-04-2019, 04:56 PM

If you have to “look it up” you really don’t have an opinion. You’re just restating someone else’s good or bad info and probably don’t know one from the other. The real HP gains from 1/4” of header isn’t that much, just as the real hp gains from 2 1/2” to 3” exhaust , of similar design, isn’t that much. If you’re looking for more than 30-40 hp don’t look at the headers. There are a lot of things that are a greater impact. You buy one set of headers then you buy another set, so you have a four digit number of dollars invested in two parts that yield less that 100 hp. For a max effort maybe that makes sense but on the street I would spend elsewhere .

QUICRNU · 01-04-2019, 08:30 PM

Based on it being a 427 with big heads and a F1-A, $900 2" kooks is a small drop in the bucket and I would do it. It will improve the power, how much is hard to say, below is my experience.

Im on a baby LSA with stock cubic inches and gmpp cnc heads.

Had the exhaust dumping after hollow cats, went from 1 3/4 stepped 1 7/8 sig series kooks to full 2" kooks.

I did not redyno, and it was not on the same night but I picked up consistent 1.5 - 2 mph trap speed on my build. Average boost level was apprix .3lbs lower with 2".

Good Luck amd let us know!

PS Get them ceramic coated.

HOJO · 01-04-2019, 08:42 PM

I would think that going with 2” you would drop in boost but maybe gain a little in power. It will let the engine breath better and easier. A boost number is no indication of power it is an indication of restriction. It would put less stress on the engine while making the same or more power.

Pro-tuned · 01-05-2019, 09:10 PM

Dropped 17 to 15.5 boost from 2 inch x 3 exhaust and HFC, but must say already had a 102 and PRC heads.

01-02-2019, 08:00 AM	#1
Bildo Drives: 2012 2SS/RS LS3 Join Date: Dec 2011 Location: Omaha, Nebraska Posts: 1,677	Restriction of 1 3/4 vs 2 inch headers Max effort F1-A 427 ERL Superdeck on E-85 setup making just 800hp with the procharger intake tube on probably around 900rwhp with it off. I have SLP 1 3/4 inch long tubes on car now that seem to be causing a bit of restriction. How much more do you think I would benefit from 2 inch headers? __________________ 2012 2SS M6, ERL Superdeck 6 427, PRC 255 Heads, Procharger F1A w/ 3.85 pulley, 1300hp intercooler, Squash Dual 450lph, E85, ID1700, RXT Clutch, DSS 1pc driveshaft, GForce axles, Eaton Detroit Trutrac, a bunch of other crap I don't feel like typing.

01-02-2019, 09:27 AM	#3
Bildo Drives: 2012 2SS/RS LS3 Join Date: Dec 2011 Location: Omaha, Nebraska Posts: 1,677	Yeah everything was dropping off early @ like 5400rpm tuner ran into this issue with his F1X vette, says the whole curve should improve with larger headers. Only able to make about 15-16lbs of boost right now with barely over spinning the blower @ 6800rpm. I also need to find some other sort of intake tube I can run on the street as a 100rwhp difference between filter on and off is a bit too much to leave on the table. __________________ 2012 2SS M6, ERL Superdeck 6 427, PRC 255 Heads, Procharger F1A w/ 3.85 pulley, 1300hp intercooler, Squash Dual 450lph, E85, ID1700, RXT Clutch, DSS 1pc driveshaft, GForce axles, Eaton Detroit Trutrac, a bunch of other crap I don't feel like typing.

01-03-2019, 07:27 PM	#5
realcanuk Drives: 2007 Corvette C6 983 RWHP Join Date: Dec 2011 Location: Montreal, Canada Posts: 690	If anything boost would be higher with a restrictive exhaust. If its not making the boost it should, I would look elsewhere for that problem. __________________ 2007 C6 vert, auto, F55, LT3 LME LS402 , WCCH 245 Heads, Pat G. Custom cam YSI / 3.0 pulley, ARH 1 7/8 headers, NPP Dewitts / dual spals, A&A dual pump fuel system. 3.42 polished gears, hardened shafts, Alky control meth, Cartech line lock, ECS axle loops, Trans brace, 6L80 built by me. ID 1000 injectors, comp rockers, Morel lifters, BT springs, Trend 3/8 pushrods, ATI 10% OD Damper Circle D Triple Disc stall 1009 RWHP @ 7000, 817 RWTQ @ 6000,

01-03-2019, 11:53 PM	#6
Js2fst 2010 transformer Drives: 2010 ss camaro Join Date: Nov 2014 Location: Lee's summit mo Posts: 591	No you are pushing a line 2" headers will make a huge difference. Look up 1 7/8 headers vs 2" gains __________________ 2010 transformer, vertical doors, 315nt05 rears, pedders supercar coilovers, hotchkis sway bars, links, adjustable, toe bars, bmr poly cradle bushings, 1le control arms, bmr tunnel brace, bmr subframe connectors. Cam 227/239-623-620@114 Mast medium bore heads, sw 1 7/8 headers, cat delete, x pipe, 3" dynomax true duals, fuel rails, fast 102 intake and NW 102 throttle body, catch can, rotofab cai, shifter, raptor custom shift light. Dss drive shaft, 3.91 gears. 492 rwhp

01-04-2019, 01:13 AM	#7
0-120 Drives: 2014 Camaro SS LS3 Join Date: May 2018 Location: GA Posts: 107 View My Garage	Isn’t there a fitment issue with the larger headers? I thought I read this concern in another topic. If not, I may consider them __________________ 416HP, 422TQ. Rotofab CAI, Dyno Tuned. ALP's and a V1.

01-02-2019, 08:26 AM	#2
Juiced1 Account Suspended Drives: 2012 2SS CAMARO 45th Join Date: Apr 2011 Location: St. Charles, IL Posts: 18,663	I can't say we've run into to many people making that upgrade. I'd love to see if they are holding you back. I would guess somewhere around 30rwhp or so.

01-03-2019, 07:00 PM	#4
UNRIVALED SS Drives: 2010 Camaro SS Join Date: Aug 2010 Location: El Paso Posts: 704 View My Garage	There is a Vette winning everything here making around 1200-1300 HP in 22 psi through. 1 7/8” headers. Probably 10 hp more or less depending on everything else you have after that

01-04-2019, 04:56 PM	#11
UNRIVALED SS Drives: 2010 Camaro SS Join Date: Aug 2010 Location: El Paso Posts: 704 View My Garage	If you have to “look it up” you really don’t have an opinion. You’re just restating someone else’s good or bad info and probably don’t know one from the other. The real HP gains from 1/4” of header isn’t that much, just as the real hp gains from 2 1/2” to 3” exhaust , of similar design, isn’t that much. If you’re looking for more than 30-40 hp don’t look at the headers. There are a lot of things that are a greater impact. You buy one set of headers then you buy another set, so you have a four digit number of dollars invested in two parts that yield less that 100 hp. For a max effort maybe that makes sense but on the street I would spend elsewhere .

01-04-2019, 08:30 PM	#12
QUICRNU Drives: Z06 wannabe Join Date: Feb 2015 Location: Daytona Beach, FL Posts: 1,200	Based on it being a 427 with big heads and a F1-A, $900 2" kooks is a small drop in the bucket and I would do it. It will improve the power, how much is hard to say, below is my experience. Im on a baby LSA with stock cubic inches and gmpp cnc heads. Had the exhaust dumping after hollow cats, went from 1 3/4 stepped 1 7/8 sig series kooks to full 2" kooks. I did not redyno, and it was not on the same night but I picked up consistent 1.5 - 2 mph trap speed on my build. Average boost level was apprix .3lbs lower with 2". Good Luck amd let us know! PS Get them ceramic coated. __________________ Apex Focused

01-04-2019, 08:42 PM	#13
HOJO Drives: 2014 Camaro SS/RS 1LE 1967 Camaro Join Date: Oct 2013 Location: Fort Wayne, IN Posts: 874	I would think that going with 2” you would drop in boost but maybe gain a little in power. It will let the engine breath better and easier. A boost number is no indication of power it is an indication of restriction. It would put less stress on the engine while making the same or more power.

01-05-2019, 09:10 PM	#14
Pro-tuned Angewendet Ingenieur Drives: 14 Camaro ZL1 Join Date: Apr 2015 Location: USA Posts: 401	Dropped 17 to 15.5 boost from 2 inch x 3 exhaust and HFC, but must say already had a 102 and PRC heads. __________________ ———— LQ9, Iron Block, Forged internals, 408CI, Jannetty custom cam, TS short block, Whipple, Hardened Jackshaft, PRC 260, 2X3 Dynatech Full Competition, HF Cats, CAI, NW 103, Chee, ID 1300, COPO Breather, MSD, Fore Dual Pump, ultratorque, E85, dual Meth, True Trac, 3:45, 1500hp axle-shafts, DSS CF, BMR, custom Pearl/Candy paint by Jaidah.