ASM or JBA headers?
09-24-2005, 10:01 AM
#12
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Originally Posted by DrX
Open exhaust! Well that removes up to 4 psi(measured at 2000 rpm) of backpressure per side(no cats- 3psi, stock catback- 1psi). Tough to compare with that factor in there.
Thanks for some numbers though.
Thanks for some numbers though.
I believe i have a dyno somewhere of the truck before and after headers (with only the converter, CAI and cat-back as mods) but I posted the only relative information i have which shows BOTH track and dyno supporting data. I have over 200 dyno pulls at all stages of my truck's development in dyno sheets and through only two shops.
In my expereince the exhaust system open and closed with the same set-up was good for 1.5 mph on the bottle and the truck had NO appreciable benefit N/A in mph. I have the cut-outs in place of cats and a 3" custom exhaust (no parts available to the general public.) On the dyno, open header nitrous passes with 4" long turn out attached to the cutouts netted 7-10 rwhp depending on the rpm. N/A i saw 2-5 rwhp .. nothing notable.
As far a CAI alone I am simply using 4" ABS plasic sewer pipe with a BLitz cone filter. The same set-up built on a friends car netted 11-12 rwhp on its own.
Having the understanding that modifications are in no way additive (not all mods are complementry) AND cumulative in whole. I think the number is very representative.
Should the CAI made: 11-12 rwhp
Open exhaust made: 2-5 rwhp
If the combination of the two are complementary (the ET/Dyno tend to suggest yes) then this suggests 13-17 rwhp is attributable to the things not related to the headers. Of the 38 rwhp that leaves 21-25 rwhp on the table. So drop-out optimal test conditions and kill 5 rwhp and that still leaves 16-20 rwhp easily and conservatively attributable to the ASM long tubes.
Descide as you will but you dont have to look hard to find justifcation to buy LTs over Shorties ... BUT you have boost ...
09-24-2005, 11:02 AM
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Originally Posted by 03rado5.3
not to hijack this thread but is anyone running longtubes on a lowered truck(4/6), if so are there any clearance issues
The headers are well above the frame line.
09-24-2005, 11:58 AM
#15
Originally Posted by oxidizr
Backpressure measurements don't = horspower gains any more than CFM flow bench numbers do. They are relative comparison points with NO direct relationship.
I believe i have a dyno somewhere of the truck before and after headers (with only the converter, CAI and cat-back as mods) but I posted the only relative information i have which shows BOTH track and dyno supporting data. I have over 200 dyno pulls at all stages of my truck's development in dyno sheets and through only two shops.
In my expereince the exhaust system open and closed with the same set-up was good for 1.5 mph on the bottle and the truck had NO appreciable benefit N/A in mph. I have the cut-outs in place of cats and a 3" custom exhaust (no parts available to the general public.) On the dyno, open header nitrous passes with 4" long turn out attached to the cutouts netted 7-10 rwhp depending on the rpm. N/A i saw 2-5 rwhp .. nothing notable.
As far a CAI alone I am simply using 4" ABS plasic sewer pipe with a BLitz cone filter. The same set-up built on a friends car netted 11-12 rwhp on its own.
Having the understanding that modifications are in no way additive (not all mods are complementry) AND cumulative in whole. I think the number is very representative.
Should the CAI made: 11-12 rwhp
Open exhaust made: 2-5 rwhp
If the combination of the two are complementary (the ET/Dyno tend to suggest yes) then this suggests 13-17 rwhp is attributable to the things not related to the headers. Of the 38 rwhp that leaves 21-25 rwhp on the table. So drop-out optimal test conditions and kill 5 rwhp and that still leaves 16-20 rwhp easily and conservatively attributable to the ASM long tubes.
Descide as you will but you dont have to look hard to find justifcation to buy LTs over Shorties ... BUT you have boost ...
I believe i have a dyno somewhere of the truck before and after headers (with only the converter, CAI and cat-back as mods) but I posted the only relative information i have which shows BOTH track and dyno supporting data. I have over 200 dyno pulls at all stages of my truck's development in dyno sheets and through only two shops.
In my expereince the exhaust system open and closed with the same set-up was good for 1.5 mph on the bottle and the truck had NO appreciable benefit N/A in mph. I have the cut-outs in place of cats and a 3" custom exhaust (no parts available to the general public.) On the dyno, open header nitrous passes with 4" long turn out attached to the cutouts netted 7-10 rwhp depending on the rpm. N/A i saw 2-5 rwhp .. nothing notable.
As far a CAI alone I am simply using 4" ABS plasic sewer pipe with a BLitz cone filter. The same set-up built on a friends car netted 11-12 rwhp on its own.
Having the understanding that modifications are in no way additive (not all mods are complementry) AND cumulative in whole. I think the number is very representative.
Should the CAI made: 11-12 rwhp
Open exhaust made: 2-5 rwhp
If the combination of the two are complementary (the ET/Dyno tend to suggest yes) then this suggests 13-17 rwhp is attributable to the things not related to the headers. Of the 38 rwhp that leaves 21-25 rwhp on the table. So drop-out optimal test conditions and kill 5 rwhp and that still leaves 16-20 rwhp easily and conservatively attributable to the ASM long tubes.
Descide as you will but you dont have to look hard to find justifcation to buy LTs over Shorties ... BUT you have boost ...
Good breakdown.
I would definitely go longtubes with NA. It's difficult to find independent comparative data for FI applications though. I can't just assume that they will perform better in FI apps simply because they do in NA apps.
09-25-2005, 10:15 AM
#16
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Originally Posted by DrX
My point was that your setup is significantly different from what I will be doing and that it would be difficult for me to isolate the effects of the headers due to the complex interaction of your multiple modifications.
Good breakdown.
I would definitely go longtubes with NA. It's difficult to find independent comparative data for FI applications though. I can't just assume that they will perform better in FI apps simply because they do in NA apps.
Good breakdown.
I would definitely go longtubes with NA. It's difficult to find independent comparative data for FI applications though. I can't just assume that they will perform better in FI apps simply because they do in NA apps.
I will be installing a set of Kook's 1 5/8" LTs on a bolt on 2004 Magnacharged C5. This is a well documented/benchmarked vehicle in the pool of cars I have modded.
Just to let you know I have tuned and modded over 8 different combination Magnacharged vehicles ranging from GTOs to Corvettes to trucks. I have also played with other brand S/C's including rotex, Procharger and vortech. As a matter of fact I just finsihed a Vortech 350Z yesterday for SEMA.
To this day my expereince has been increased exhaust effieciency nets better cylinder evacuation leading to a drop in boost over stock manifolded/catted/mufflered trucks.
09-25-2005, 12:23 PM
#17
Originally Posted by oxidizr
To this day my expereince has been increased exhaust effieciency nets better cylinder evacuation leading to a drop in boost over stock manifolded/catted/mufflered trucks.
That is exactly what I want to achieve. Maximized flow for decreased boost pressure/increased compressor effieciency. The basic principles to achieve this are the same whether NA or FI. Not sure yet if there are any factors unique to FI that require special consideration when shooting for optimal performance.
Other thoughts:
The headers should incorporate equal flow(not necessarily equal length) tube design for optimal timing of exhaust pulses
Collector design is also important
I'm not sure if coatings make a significant difference to performance
What is the ideal tube diameter for my app(and this will probably vary with tube length.
09-26-2005, 08:09 PM
#18
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I saw a tremendous gain with my asm headers. I dont have a dyno graph to prove it but i felt a very noticable change, they are of good quality, and are easy to install too. Asm over jba defenately.
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