Throttle body size question
Thread Starter
Instructor
Joined: Oct 2016
Posts: 121
Likes: 1
From: Chicago area Illinois
Throttle body size question
Assuming size matters, I have a stock 2003 and I am starting to add some performance enhancing bolt-ons, like headers, CAI, and a tune.
I want to know if a new larger throttle body is recommended. What size is stock an what size is recommended?
Thanks,
Gary
I want to know if a new larger throttle body is recommended. What size is stock an what size is recommended?
Thanks,
Gary
Last edited by Geboe; Dec 25, 2016 at 02:28 PM. Reason: Grammer correction
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
On a stock 2003 I don't see the throttle body to be a bottleneck. Unless you have made substantial modifications to the engine I don't see much benefit. A larger TB will require the mouth of the intake manifold to be ported witch may help at WOT.
A CAI and a tune will yield HP gains (20-35HP). CAI alone (10-15HP). A freer flowing exhaust may be good for (10-20HP). These are just estimates. People will argue with me but I don't see headers really adding any HP to a stock LS1. The stock manifolds work fine on the 405+HP of the Z06. I would go with a cat back exhaust and possibly gut the pre-cats.
A CAI and a tune will yield HP gains (20-35HP). CAI alone (10-15HP). A freer flowing exhaust may be good for (10-20HP). These are just estimates. People will argue with me but I don't see headers really adding any HP to a stock LS1. The stock manifolds work fine on the 405+HP of the Z06. I would go with a cat back exhaust and possibly gut the pre-cats.
Last edited by Rob 02; Dec 25, 2016 at 11:51 PM.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I agree---Unless you plan on running your engine consistently over 6500 RPM's OR have larger than stock cubic inches a larger T-Body will NOT give you any HP advantage and will create some drive ability issues unless you get a re -tune---
Your best option is to get your STOCK T-Body professionally ported----There are several companies that can do this for you--Typical cost is between $150 and $250----This is all you really need A ported T-body most always adds about 7-10 RWHP however the throttle response really wakes a drive by wire throttle wake up---AND no tuning is required--------If you go to a larger aftrmarket like a BBK 80 T-Body it will require tuning otherwise you may go backwards in HP--------
Your best option is to get your STOCK T-Body professionally ported----There are several companies that can do this for you--Typical cost is between $150 and $250----This is all you really need A ported T-body most always adds about 7-10 RWHP however the throttle response really wakes a drive by wire throttle wake up---AND no tuning is required--------If you go to a larger aftrmarket like a BBK 80 T-Body it will require tuning otherwise you may go backwards in HP--------
Thread Starter
Instructor
Joined: Oct 2016
Posts: 121
Likes: 1
From: Chicago area Illinois
On a stock 2003 I don't see the throttle body to be a bottleneck. Unless you have made substantial modifications to the engine I don't see much benefit. A larger TB will require the mouth of the intake manifold to be ported witch may help at WOT.
A CAI and a tune will yield HP gains (20-35HP). CAI alone (10-15HP). A freer flowing exhaust may be good for (10-20HP). These are just estimates. People will argue with me but I don't see headers really adding any HP to a stock LS1. The stock manifolds work fine on the 405+HP of the Z06. I would go with a cat back exhaust and possibly gut the pre-cats.
A CAI and a tune will yield HP gains (20-35HP). CAI alone (10-15HP). A freer flowing exhaust may be good for (10-20HP). These are just estimates. People will argue with me but I don't see headers really adding any HP to a stock LS1. The stock manifolds work fine on the 405+HP of the Z06. I would go with a cat back exhaust and possibly gut the pre-cats.
Melting Slicks
Joined: Feb 2001
Posts: 2,804
Likes: 358
From: Northville, MI
Any cat back system you buy is for the sound, The Z06 TI added about 3 hp to the Z06 according to the GM head Powertrain engineer who spoke to our club several years ago. He mentioned that other than the Corsa TI straight pipe or similar, you will not gain anything noticeable in power gains. If you add a true CAI you will need a good tune to realize any HP gains 10-15hp, otherwise, without a tune, you might actually lose hp (The incoming air is denser-more oxygen-and the many fueling tables may not be able to supply optimal air/fuel mixture). Also the TB is drive-by-wire and a good tune will also eliminate some of the delay associated with it.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
There is no magic in ANY aftermarket cat-back exhaust system-----Typically most all brands will only add from 3-8 RWHP
Sound in the major reason to choose one brand or design over another-----Everyone has different tastes in what they like----
Sound in the major reason to choose one brand or design over another-----Everyone has different tastes in what they like----
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
Exhaust and intake's don't add HP they restrict it on some level. Weather or not it makes a difference for your set up depends on a lot of factors. On a stock LS1 I don't see much of a gain from headers alone. What HP is gained is most likely from the freer flowing cats. When you start making more HP the exhaust starts wanting to breath more.
With 350HP you may see a 3HP increase with headers but at 500HP You may notice a 35HP gain for example. The stock manifolds aren't that restrictive for a stock application. Some people have reported a 20HP gain with a tune and headers, but a tune alone can get you 10-15HP.
People do like headers though, and kind of expect them.
With 350HP you may see a 3HP increase with headers but at 500HP You may notice a 35HP gain for example. The stock manifolds aren't that restrictive for a stock application. Some people have reported a 20HP gain with a tune and headers, but a tune alone can get you 10-15HP.
People do like headers though, and kind of expect them.
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
Free flowing exhaust; buy for sound not power. Maybe 5HP gain on a stock LS1.
And while the stock manifolds are fine, headers and a tune are an easy 25-40 depending on motor. Not arguing, there many internet posts with proven dyno results.
Thread Starter
Instructor
Joined: Oct 2016
Posts: 121
Likes: 1
From: Chicago area Illinois
CAI getting 10-15 is a push from what I've seen, more like 5-10?
Free flowing exhaust; buy for sound not power. Maybe 5HP gain on a stock LS1.
And while the stock manifolds are fine, headers and a tune are an easy 25-40 depending on motor. Not arguing, there many internet posts with proven dyno results.
Free flowing exhaust; buy for sound not power. Maybe 5HP gain on a stock LS1.
And while the stock manifolds are fine, headers and a tune are an easy 25-40 depending on motor. Not arguing, there many internet posts with proven dyno results.
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
The remainder of the factory exhaust is very good, you might gain 5HP from removing/gutting cats, another 5 usually from a cat back if lucky.
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
The stock air box is restrictive. I think you could get 20 with just CIA and a tune. The mods you are talking about are so common that there is a ton of information on this if you do a search. You will get multiple results on the exact mods you are considering.
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
I could provide a link to a Super Chevy test but it was on an LS6. There was no substantial gain with headers alone until they tuned it then about 20HP. Again the tune is good for about 15.
http://www.superchevy.com/how-to/050...te-motor-test/
I cant imagine the LS1 needing the headers any worse.
I am not a fan of the pup cats/ pre-cats either. They are probably responsible for 3-5 HP.
http://www.superchevy.com/how-to/050...te-motor-test/
I cant imagine the LS1 needing the headers any worse.
I am not a fan of the pup cats/ pre-cats either. They are probably responsible for 3-5 HP.
Burning Brakes
Joined: Jan 2000
Posts: 831
Likes: 31
From: Merritt Island Florida
Headers make a big difference on an LS1 even a stock one.
For your needs a stock ported throttle body is fine. Attack what is in front of it. Callaway and Varam make the best C5 systems in terms of power. Not easy to install though
For your needs a stock ported throttle body is fine. Attack what is in front of it. Callaway and Varam make the best C5 systems in terms of power. Not easy to install though
Melting Slicks
Joined: Mar 2009
Posts: 2,300
Likes: 115
From: Odessa FL
St. Jude Donor '10-'12-'13-'14-'15-'16-'17
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
Also take into account your driving needs.If you are just having fun on the street then the stock low end torque is nice. Some of the mods only show yields at high RPM's or at WOT.
A lower rear gear may be what you are really looking for.