Dyno testing Corvette Manfolds against headers
Thread Starter
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From: Corsicana, Tx
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LOL...like no thought went into any of those huh?? Would have been a lot simpler to make a log design.
The OEM's fight all sorts of things we don't have to worry about. Cat temperatures that have to increase immediately for emissions, NVH (mandated and customer), costs, 100K mile warranties, have to make it "idiot proof" for any fool that wants to jump ditches or speed bumps at 50 mph, and on and on.
The fact that they've put so much work into exhaust as part of the engine package shows they know where the performance is for fuel, emissions and power. If all those constraints were lifted...certainly they'd take advantage of the tuning possibilities.
JIM
The OEM's fight all sorts of things we don't have to worry about. Cat temperatures that have to increase immediately for emissions, NVH (mandated and customer), costs, 100K mile warranties, have to make it "idiot proof" for any fool that wants to jump ditches or speed bumps at 50 mph, and on and on.
The fact that they've put so much work into exhaust as part of the engine package shows they know where the performance is for fuel, emissions and power. If all those constraints were lifted...certainly they'd take advantage of the tuning possibilities.
JIM
Le Mans Master
Joined: Apr 2011
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From: Hermosa
Not a chassis dyno, but it illustrates the clear advantage of headers over manifolds on even a mild smallblock. +34 HP and +53 tq.
http://www.google.com/url?sa=t&rct=j...7QOv5rZxDzXv2A
Now please shut up.
http://www.google.com/url?sa=t&rct=j...7QOv5rZxDzXv2A
Now please shut up.
We'll start with a very mild Goodwrench 350ci small-block test with stock cam timing. The idea here is to compare the power output of a stock small-block 350 with cast-iron exhaust manifolds and headers. Because this is a mild engine, the peak power difference occurred relatively early in the power curve, with a maximum 34 hp and 53 lb-ft of torque gain at 3,400 rpm. That's an excellent 19 percent improvement in torque. Had the engine been fitted with a decent camshaft to allow the engine to make more power around 5,000 rpm, the improvement would have been even greater. However, this test does point out that even a stock engine will respond to a decent set of headers. As power potential increases with a good set of heads and a camshaft, headers and a free-flowing exhaust system become absolutely essential components.
Last edited by REELAV8R; Jan 14, 2016 at 06:17 PM.
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From: San Jose CA
And for those who'll jump to GM's info on the GW350 and claim it's "not the same as a stock Corvette engine"; the GW350 has the same heads (462624) and same cam as a 78 L-48. Compression ratio is rated at 8.5:1, higher than the typical 8.2:1 for an L-48. However, there are more than a few articles claiming the GW350 overrated its compression ratio. Regardless, 0.3 points of static CR is insignificant for the purpose. An L-48 will still see huge gains from proper headers.
Thread Starter
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From: Corsicana, Tx
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Aren't those gorgeous?
JIM
PS- I've got the same engine stand that Mystery 427 is on. Stroppini Enterprises....those bad boys can hold the big boys!!
JIM
PS- I've got the same engine stand that Mystery 427 is on. Stroppini Enterprises....those bad boys can hold the big boys!!
Last edited by 427Hotrod; Jan 14, 2016 at 09:48 PM.
Thread Starter
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Those are sweet. You could swap heads right for left and run the exhaust out the normal way for cars that needed it.
JIM
JIM
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From: Plano TX
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From: Hermosa
That's a good looking graph. My LTH definitely added significant power even to the stock motor when I put them on. No dyno to prove it though. Yours proves it.
Melting Slicks
Joined: Mar 2008
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From: Meriden CT
The Hot Rod article states the test WAS done with a full 2 1/2 inch exhaust thru turbo mufflers, back to back comparison only changing from manifolds to headers, NO other changes. If you don't read the evidence YOU demanded, how can you rationally deny it?
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
This thread has run amok since page one. If you don't like it don't open it. It is very clear one side has supported the use of long tube headers with more than enough evidence.
That should be it, no reason to come back and complain, especially on page three. What are you doing on page three ? It was all over on page one. I like the cheap entertainment
That should be it, no reason to come back and complain, especially on page three. What are you doing on page three ? It was all over on page one. I like the cheap entertainment
Safety Car
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From: anchorage ak
Put a set on, you might keep up with the modded l48's with your high potency big block. Common, you know you want to.
Melting Slicks
Joined: Apr 2009
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From: Great Plains Iowa
The problem with long tube headers is they are designed to be run OPEN so the increased flow of exhaust gasses get vented to the atmosphere. Run an exhaust system with mufflers behind them and any gain is lost. The performance dollar is better spent elsewhere......................
Pro
Joined: Oct 2009
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From: Marysville Ohio
The problem with long tube headers is they are designed to be run OPEN so the increased flow of exhaust gasses get vented to the atmosphere. Run an exhaust system with mufflers behind them and any gain is lost. The performance dollar is better spent elsewhere......................
And per Zwede's comments, that was a before-and-after with the same mufflers.
And please explain - where is the performance dollar better spent? the ONLY cheaper option I have found is an advanced timing curve and tune - and I have read more than one post by you against advanced ignition timing beyond the factory settings.
Aside from a properly setup advance curve, headers/exhaust are the best seat of the pants performance upgrade you can make. And headers really go hand in hand with ignition timing and carb tuning.
I usually try to avoid making posts like this. I am not nearly the most experienced person on this forum. I truly hope the other less experienced on here can also see through the misleading "advice" you offer on this forum as I do.
Racer
Joined: Feb 2007
Posts: 259
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From: Valrico Florida
I'm sure someone on here would really like to contact HOOKER, HEDMAN, KOOKS etc and let them know about this thread.
Bet you wouldn't have the stones to pick up the phone
Melting Slicks
Joined: Mar 2008
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From: Meriden CT
You don't get invited to too many parties, do you? Haha. Dynos aren't hype. You've been provided with links to published documentation. Read them and respond with a rational argument of why they are wrong, instead of simply being contrary. And as always.....HAPPY MOTORING!!!!
Pro
Joined: Oct 2009
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From: Marysville Ohio
rdrocket - not sure who that is directed to?
I don't claim to be the most knowledgeable person, but I absolutely have been around long enough to know a good timing curve and improved exhaust flow are among the lowest cost performance upgrades.
AS for TooBroke's response - I pointed out that there have been posts in this thread with before/after dyno pulls - something you requested in this thread but have yet to actually respond to.
I am asking for a direct response to those posts that contain data from a dyno session, not commentary on my preference for headers.
If the dyno data presented is wrong, please enlighten us.
I don't claim to be the most knowledgeable person, but I absolutely have been around long enough to know a good timing curve and improved exhaust flow are among the lowest cost performance upgrades.
AS for TooBroke's response - I pointed out that there have been posts in this thread with before/after dyno pulls - something you requested in this thread but have yet to actually respond to.
I am asking for a direct response to those posts that contain data from a dyno session, not commentary on my preference for headers.
If the dyno data presented is wrong, please enlighten us.
Last edited by cooper9811; Jan 17, 2016 at 11:41 AM.
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From: anchorage ak
Alright steve, put up, it's your turn to substantiate your claims with proof, Mr. Swede posted a dyno comparison on manifolds versus headers that clearly prove you wrong, we're is your proof, don't say because the auto manufacturers don't do it, that's like saying the government uses it, it must be good, why shouldn't we..We get that you don't like headers, good for you, but for those of us that prefer and use headers, you won't change our thoughts on the matter nor have you substantiated your claims. You've not put up one shred of proof to your position in this matter. You run a larger cam, aluminum intake and an overdrive transmission, the auto manufacturers didn't install those items in your vette originally and don't now, are those items just to make you think youve accomplished something and hype.....or do they actually produce more power...of course they produce more power and no the auto manufacturers didn't install them. Don't forget to buy your free health care after all the government says it's good...
Last edited by bluedawg; Jan 17, 2016 at 01:11 PM.