How to gut your primary cats (Dyno results to come soon)
08-08-14, 02:38 PM
#77
Has only been tested by one set of cars doesn't mean it holds true for all cars. Lots of variables, wheels? other mods? Has the car with the aftermarket headers had his ECU learn the modification? Could be anything.. but the difference should be more than obvious.
08-08-14, 03:28 PM
#78
I know there are a lot of variables but dynos have lots of variables as well. Anyways I'd trust more a repeated comparison between two well known members, with similarly modded cars and circumstances, where many of the variables are equal, than dyno comparisons taken in completely different circumstances. I'd at least try out the gutted cats before getting headers.
Last edited by jat0223; 08-08-14 at 03:37 PM.
08-08-14, 04:31 PM
#79
I know there are a lot of variables but dynos have lots of variables as well. Anyways I'd trust more a repeated comparison between two well known members, with similarly modded cars and circumstances, where many of the variables are equal, than dyno comparisons taken in completely different circumstances. I'd at least try out the gutted cats before getting headers.
Anyways, a 6whp gain is acceptable for gutless OEM headers but overall a set of truly engineered headers will outperform stock across the powerband. Have you seen an F1 car's with headers like our stock ones?
08-08-14, 05:04 PM
#80
I think people buying gutted cats are having wishful thinking that they can get the most power out of a basic header.. go on any automotive forum and I've never seen OEM catless headers out performing 4-1 or 4-2-1 headers with larger runners and collectors. It's basic physics and its funny 2 members giving us their story will change so many minds and block us from our logic.
Anyways, a 6whp gain is acceptable for gutless OEM headers but overall a set of truly engineered headers will outperform stock across the powerband. Have you seen an F1 car's with headers like our stock ones?
Anyways, a 6whp gain is acceptable for gutless OEM headers but overall a set of truly engineered headers will outperform stock across the powerband. Have you seen an F1 car's with headers like our stock ones?
08-08-14, 05:09 PM
#81
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Its a bit too late for me to dyno my car without gutted cats so all I can go by are real time situations. Fact is that ill race any I/H/E ISF and win without issue if im not sandbagging. Ill even head down to my storage unit to get the intake from my old car to make things as fair as possible.
08-08-14, 06:38 PM
#82
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Difference is the the aftermarket headers really and truly dont make more power than the gutted cats. You can buy into the posted dyno results all you want, fact of the matter is that there not going to be accurate considering there were other changes to the car in between the dyno sections.
Its a bit too late for me to dyno my car without gutted cats so all I can go by are real time situations. Fact is that ill race any I/H/E ISF and win without issue if im not sandbagging. Ill even head down to my storage unit to get the intake from my old car to make things as fair as possible.
Its a bit too late for me to dyno my car without gutted cats so all I can go by are real time situations. Fact is that ill race any I/H/E ISF and win without issue if im not sandbagging. Ill even head down to my storage unit to get the intake from my old car to make things as fair as possible.
08-08-14, 06:41 PM
#83
Difference is the the aftermarket headers really and truly dont make more power than the gutted cats. You can buy into the posted dyno results all you want, fact of the matter is that there not going to be accurate considering there were other changes to the car in between the dyno sections.
08-08-14, 07:49 PM
#84
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No. He said he won, I said I won. Not really going to argue with him because the race was close enough to call tie. Cant say for what Danny had in his trunk, but if hes was empty my car was 80lbs over weight. I haven't taken racing seriously for a while, but now that im making moves to get back in the game my car will be on point next time we run.
I can claim it all I want until a header car out runs me. Remember, I had sikky headers on my previous ISF and removed them because they didnt perform as well as my gutted cat setup.
I really have no idea where your getting this 'double the flow" figure from. If you can physically see and calculate the flow then kudos to you. But if you cant, you cant really claim anything considering that the wheels increased in weight for run 2.
Anyone in South Florida have a VBox????
how can this even be claimed? There is a drastic difference in gains between the gutted cat chart and the header chart (red vs green) especially in the top end above 5000rpm. The gutted cat dyno has 8rwhp grid marks and its pretty much 2 grid marks from 3500-5500, but that means 16rwhp , so not sure where 25-28rwhp as stated above is coming from. The aftermarket headers easily have double the flow rate of the stock headers. The piping diameter looks the same but two cylinders are sharing a pipe on stock, aftermarket each cylinder has a dedicated pipe - doubling the flow. Its not a surprise why it makes large gains in the top end with a huge reduction in backpressure due to double the flow over stock headers.
I really have no idea where your getting this 'double the flow" figure from. If you can physically see and calculate the flow then kudos to you. But if you cant, you cant really claim anything considering that the wheels increased in weight for run 2.
Anyone in South Florida have a VBox????
08-08-14, 09:47 PM
#85
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although the oem headers are not something pretty to look at, im sure it flows nice and engineered well.
PPE might look crazier making you think it its superior but i use to think about this all the time. im not sure of PPE r+d is set up like but a lot of power usually is from losing the cats. ive noticed that with the PPE headers on my previous 350z as well. they are not equal length, im not sure if PPE tried various designs. Although great company and craftsmanship. i was very satisfied with both sets of headers in person even though i sold my ISF set before installing.
Headers on the m5/m6 v10, makes the same gains from nice tubular aftermarket headers and with oem headers with the cats off as well. and members actually prefer to cut the cats off instead because the welds dont mess up down the road like the aftermarket headers which have been happening on that platform.
MRxSlay might be on to something but im glad there are members doing this and sharing this information. very useful.
PPE might look crazier making you think it its superior but i use to think about this all the time. im not sure of PPE r+d is set up like but a lot of power usually is from losing the cats. ive noticed that with the PPE headers on my previous 350z as well. they are not equal length, im not sure if PPE tried various designs. Although great company and craftsmanship. i was very satisfied with both sets of headers in person even though i sold my ISF set before installing.
Headers on the m5/m6 v10, makes the same gains from nice tubular aftermarket headers and with oem headers with the cats off as well. and members actually prefer to cut the cats off instead because the welds dont mess up down the road like the aftermarket headers which have been happening on that platform.
MRxSlay might be on to something but im glad there are members doing this and sharing this information. very useful.
08-09-14, 05:28 AM
#86
the gutted dynos have not proven that they are better than aftermarket headers, especially that top end. That dyno only proves how much power removing cats gains which is only a portion of what real headers give. Therefore, its not just the cats that are restricting flow. If the OEMs are so engineered well how come there is a huge gain on top end with aftermarket headers? That means theres a lot of backpressure on OEM - lack of flow. Seeing how the gutted cats barely gained anything on top end, the bottleneck is the header design, not the cats.
08-09-14, 10:18 AM
#87
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the gutted dynos have not proven that they are better than aftermarket headers, especially that top end. That dyno only proves how much power removing cats gains which is only a portion of what real headers give. Therefore, its not just the cats that are restricting flow. If the OEMs are so engineered well how come there is a huge gain on top end with aftermarket headers? That means theres a lot of backpressure on OEM - lack of flow. Seeing how the gutted cats barely gained anything on top end, the bottleneck is the header design, not the cats.
Dynojet, mustang dyno, dynopack etc all give very different numbers. Every comparison header chart on the forum has been run on a dynojet.
The dyno used here reads 11-18% lower than a dynojet if you believe numerous different car forums scattered all over the net.
The point here is this was a 45 minute mod that yielded unbelievable gains throughout the RPM range for next to nothing. There are no rattles, no signs of modification, and your wallet remains $1500-1800 heavier.
True test is going to be a race. Lol I don't understand why you guys are trying to dismiss this mod when its far more convenient than headers. It's just another option for a severely limited aftermarket selection.
08-09-14, 11:58 AM
#89
no ones dismissing that the gutting mod makes power. Whats being dismissed is the claim that it makes the same power as real headers. That was the objective of this thread and when it didnt pan out people back tracked to "well i win races with it" as the proof. This thread had trying to prove a pre determined conclusion written all over it. Doing a race proves little either, only that you won a race. It doesn't conclusively prove that gutting = aftermarket header power due to the huge amount of variables between two different cars and two different drivers.
08-09-14, 12:12 PM
#90
no ones dismissing that the gutting mod makes power. Whats being dismissed is the claim that it makes the same power as real headers. That was the objective of this thread and when it didnt pan out people back tracked to "well i win races with it" as the proof. This thread had trying to prove a pre determined conclusion written all over it. Doing a race proves little either, only that you won a race. It doesn't conclusively prove that gutting = aftermarket header power due to the huge amount of variables between two different cars and two different drivers.
Please show me "properly design" R&D that went into Sikky and PPE headers. I have Sikky and I like it for what it is, don't get me wrong. Any headers that are not equal length (or better yet, equal length long tubes) are not "properly designed