Highest HP From 243 Heads?
Yeah, I had a couple of things stopping me from increasing the limit. I'm currently running a stock GM replacement oil pump and my injector duty was at 94% (Fast 36lbs/ 42lbs @58).
I will install a high pressure melling when I swap the cam and injectors. We'll see how the heads perform and then will install bigger heads.
I will install a high pressure melling when I swap the cam and injectors. We'll see how the heads perform and then will install bigger heads.
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Joined: Feb 2004
Posts: 818
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From: VA
On my data log it showed to be spinning to 7k but the shops dyno graph was not matching.
Last edited by LaBLKv6Z; Jun 14, 2019 at 03:30 PM. Reason: image added
Is it ported? I’ve ran the Melling high pressure and high volume in the ls1. I decided to run the OEM pump this time around but thinking about going to the high pressure again when I open it up.
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Originally Posted by bortous
So it's a 427.
I think 2 inch headers is overkill at this power level.
I think 2 inch headers is overkill at this power level.
TECH Addict
Joined: Sep 2010
Posts: 2,898
Likes: 467
I found an interesting article actually about headers.
This guy in WA did extensive testing using the same engine. Go to www.streetquick.com.au
First with 1 3/4 headers, then with 1 7/8 then with a fast and stock ls3 intake with each headers size.
The combo that ran the most consistent was with the 1 3/4 pipes.
However for some reason when this combo was paired with a 102mm throttle body, the FAST 102mm and the 1 7/8 this pulled the fastest time.
This might be right as when I switched over from 1 3/4 to 1 7/8 I gained nothing.
Now that I remember, the manufacturer of my headers once did tell me you would only go the 1 7/8 size if you were over 800hp.
I'm sure these manufacturers know exactly how big you need to go for each power level....
For some things, it's so difficult to find definitive results.
No it's not ported. Schawanky who built hammers bottom end said porting them did nothing in their testing.
I think your key there is intake size. Engines are like lungs. They can only breathe in what they breathe out AND can only breathe out what they first breathe in.
Smaller intake, making to larger headers made no difference. Larger intake there were gains?
Link was just to main page. No article.
Smaller intake, making to larger headers made no difference. Larger intake there were gains?
Link was just to main page. No article.
TECH Veteran
Joined: Sep 2014
Posts: 4,893
Likes: 703
From: Mississippi
Haha. Maybe I did, maybe I didn't.
I found an interesting article actually about headers.
This guy in WA did extensive testing using the same engine. Go to www.streetquick.com.au
First with 1 3/4 headers, then with 1 7/8 then with a fast and stock ls3 intake with each headers size.
The combo that ran the most consistent was with the 1 3/4 pipes.
However for some reason when this combo was paired with a 102mm throttle body, the FAST 102mm and the 1 7/8 this pulled the fastest time.
This might be right as when I switched over from 1 3/4 to 1 7/8 I gained nothing.
Now that I remember, the manufacturer of my headers once did tell me you would only go the 1 7/8 size if you were over 800hp.
I'm sure these manufacturers know exactly how big you need to go for each power level....
For some things, it's so difficult to find definitive results.
I found an interesting article actually about headers.
This guy in WA did extensive testing using the same engine. Go to www.streetquick.com.au
First with 1 3/4 headers, then with 1 7/8 then with a fast and stock ls3 intake with each headers size.
The combo that ran the most consistent was with the 1 3/4 pipes.
However for some reason when this combo was paired with a 102mm throttle body, the FAST 102mm and the 1 7/8 this pulled the fastest time.
This might be right as when I switched over from 1 3/4 to 1 7/8 I gained nothing.
Now that I remember, the manufacturer of my headers once did tell me you would only go the 1 7/8 size if you were over 800hp.
I'm sure these manufacturers know exactly how big you need to go for each power level....
For some things, it's so difficult to find definitive results.
11 Second Club
Joined: Mar 2012
Posts: 1,541
Likes: 15
From: South Florida
With header size. I think it was one of the best mods I've done moving to 2" headers. As at my power level the 1 7/8 would have been fine. With exhaust also a very important thing is header back. You could have the biggest headers but if still, to say a single over axle setup, may not do much. After moving from 1 3/4" to the 2" headers. The engine felt so much more relaxed from less back pressure I'd say. As when holding the engine at 4500-5000rpm, with the 1 3/4, waiting for a hit. It needed more throttle to keep it there & felt like brakes if you let off. With the 2" headers you feel the motor can spin that high feeling much easier. Or not as much draw back from say letting off or to just hold it there.
Last edited by SoFla01SSLookinstok; Jun 15, 2019 at 01:29 PM.
TECH Addict
Joined: Sep 2010
Posts: 2,898
Likes: 467
With header size. I think it was one of the best mods I've done moving to 2" headers. As at my power level the 1 7/8 would have been fine. With exhaust also a very important thing is header back. You could have the biggest headers but if still, to say a single over axle setup, may not do much. After moving from 1 3/4" to the 2" headers. The engine felt so much more relaxed from less back pressure I'd say. As when holding the engine at 4500-5000rpm, with the 1 3/4, waiting for a hit. It needed more throttle to keep it there & felt like brakes if you let off. With the 2" headers you feel the motor can spin that high feeling much easier. Or not as much draw back from say letting off or to just hold it there.