Doug Thorley headers question

[topgun1]

Originally Posted by axis

I'm not doubting your numbers in any way as them seem fair. I just question the MANUFACTURERS claims on shorty's alone. Shorties bolted up to OEM cats. No one seems to have any independent data to back up DT's or any other companies claims of 15+whp gains.

i'm in agreement with you there. I never see duplication of manufacturer's claims of power gains on products.

[bi11ymc]

According to Bad Karma's dyno graph in this thread on a stock LS3:

10.86 rwhp
6.28 rwtq

[Wilburbeest]

Originally Posted by topgun1

check my thread out, you may find it useful. I have dynoed with DT shorty headers on my SS with hiflow cats. definite power gains at least between both of them. Also, DT's shorties and longtubes have neglible difference in HP gains on their website dyno graphs and the shorties have a little more low end torque. I'm happy with my shorties, they are less expensive, still ceramic-coated, they are not throwing codes (headers or cats) and dont' have to worry about clearance issues with the long tubes since my car is lowered. i have tuned so likely voided my warranty but shorties shouldn't if you haven't tuned. I'd go with the DT shorties and replace the stock cats with SOLO hiflow cats. The sound you'll get with the new cats is amazing. good luck!

http://www.camaro5.com/forums/showthread.php?t=91945

Props for giving it a try and documenting it, but honestly It looks like the majority of your gain was in the tune and high flow cats. 25ish hp seems about right for that. I don't mean to down your setup or sound like a broken record because I JUST said this in another thread, but these engines basically already have shorty headers. All you are getting with aftermarket is a negligibly better version of what you already have.

[bi11ymc]

I am going with the DT Shorties because of the annual visual inspection under the car from the Vehicle Inspection Station for renewal of my license plate.

Though the gains are not as good as long tubes, they do look better, are lighter weight and will produce less heat under the hood (ceramic coating). I didn't want to stay with the stock manifolds because I am getting a cam and TVS 2300 installed in the near future (parts are on order from Vengeance Racing).

[topgun1]

Originally Posted by Wilburbeest

Props for giving it a try and documenting it, but honestly It looks like the majority of your gain was in the tune and high flow cats. 25ish hp seems about right for that. I don't mean to down your setup or sound like a broken record because I JUST said this in another thread, but these engines basically already have shorty headers. All you are getting with aftermarket is a negligibly better version of what you already have.

Well I can't read both posts at the same time and well you kinda are sounding like a broken record. If you reread my post, with no tune, there was a 12 rwhp, 24 rwtq gain between the headers and the cats. So as you see, almost all of the torque gain was from a combo of the headers and cats. The shorties are known for low end torque, but now unfortunately I wasn't able to dyno those separately, but it is what it is, so we'll never know. With a tune in 100 degree weather, high humidity was an additional 14 rwhp, and 1-2 rwtq, total gains of 27 rwhp, 26 rwtq. I'll be back on a cooler, drier day to post even higher gains.

I'm glad you are happy with your LTs on your LT1. Maybe you have a few more hp than the shorties, but I'm putting well over 400 hp to the ground now so I'm not complaining. I think once you get a new SS, you won't be bashing as often. take a look at Doug Thorley's website, there are neglible difference in gains between their shorties and long tubes in hp and the shorties actually have more torque. Take a look at other sites too, you just wont' see big power differences. I don't have to worry about clearance issues with my lowered car as some people have with the LT's, they're less expensive, they are ceramic-coated, dissipate heat better, lighter, look great, sound great, no CEL, etc. I am completely happy with my setup with a complete free-flowing exhaust system. So for some extra piping and a few more ponies, it's not worth it for me or many other people on the forum.

hey, at least we both can agree that we enjoy owning Camaros.

[3GPa]

Originally Posted by topgun1

Well I can't read both posts at the same time and well you kinda are sounding like a broken record. If you reread my post with an excerpt below, with no tune, there was a 12 rwhp, 24 rwtq gain between the headers and the cats. So as you see, almost all of the torque gain was from a combo of the headers and cats. The shorties are known for low end torque, but now unfortunately I wasn't able to dyno those separately, but it is what it is, so we'll never know. With a tune in 100 degree weather, high humidity was an additional 14 rwhp, and 1-2 rwtq, total gains of 27 rwhp, 26 rwtq. I'll be back on a cooler, drier day to post even higher gains.

I'm glad you are happy with your LTs on your LT1. Maybe you have a few more hp than the shorties, but I'm putting well over 400 hp to the ground now so I'm not complaining. I think once you get a new SS, you won't be bashing as often. take a look at Doug Thorley's website, there are neglible difference in gains between their shorties and long tubes in hp and the shorties actually have more torque. Take a look at other sites too, you just wont' see big power differences. I don't have to worry about clearance issues with my lowered car as some people have with the LT's, they're less expensive, they are ceramic-coated, dissipate heat better, lighter, look great, sound great, no CEL, etc. I am completely happy with my setup with a complete free-flowing exhaust system. So for some extra piping and a few more ponies, it's not worth it for me or many other people on the forum.

hey, at least we both can agree that we enjoy owning Camaros.

Nice Post!

[ssmike]

[Ivan @ Southwest Speed]

The dyno tests are quite subjective...remember that all are different and creating the same exact conditions are not always relative.

That's why we did the independant test. We actually ran the "after" 9 times. Yes....9.

This was about the middle as there were some much lower and also much higher numbers. (+/-6 HP)

This information was shared since it was thought to be helpful to those who really wanted true, independant numbers not being paid for by the manufactures numbers. The dynos actually stemmed from a customer who felt what they thought was a "loss" in HP after the swap.

That's why there were so many afters done.

Woulda been great to get that many "before" dynos to see more information.

Food for thought as always..
Ivan

[Wilburbeest]

Originally Posted by topgun1

Well I can't read both posts at the same time and well you kinda are sounding like a broken record. If you reread my post, with no tune, there was a 12 rwhp, 24 rwtq gain between the headers and the cats.

Dude its not my intention to bash anybody. Sorry if I seemed like a dick a couple posts ago. I'm just here to learn about the new Camaro because I want one when I can get one and to share a little bit of what I already know since I've been into LS/LT engines for a while now. Like I said agree to disagree, man. But I do want to say you're just making my point for me.

The cats are a pretty decent bottleneck on these cars and I wouldn't doubt gave you as much or more gain than the headers did. Then 27hp total with the tune....well with the car totally stock lets just be SUPER conservative putting numbers in favor of the shortys since neither one of us has super solid numbers. So lets say your tune gave you 15 hp if its even half decent and your high flow cats gave you 5hp. At that rate your $500 shortys gave you a grand total of 7hp, and again that's being SUPER generous. As for the low end torque part.....well if somebody can give a back to back dyno with just the shortys I'll eat my words, but the shape of your torque curve is damn near identical except from 2500-3k, which does admittedly look a bit better. Infact from 3-4k the stock and final ramp up nearly the same exact amount. That doesn't really look much like the headers did much to your torque curve.

I'm enjoying this debate though dude, that's what these forums are for and IMO it benefits both sides

EDIT: Wow I just realized the $500 set was the V6 set. $810 for that small of a gain? No thanks but I'm glad you're happy with your setup. I see the negligible differences you're talking about on DT's dyno graphs. I'll go with the independent dynos from LT1/LS1/LS2/LS3 engines I've seen over about the past 5 years instead though. I doubt that Doug Thorley has come up with some crazy header voodoo that the other manufacturers haven't over the past however many decades shortys have been manufactured. There's a reason why nobody ever bothered with them before emissions testing was an issue. They are worth a bit more on older engines though because the typical factory manifolds barely belong on a tractor, let alone a performance engine.

[bi11ymc]

I paid less than 475.00 for the DT Shorties shipped! The guys at Vengeance Racing are going to replace my complete exhaust system while doing my suspension, cam and supercharger. My Borla Touring cost more than twice that for no gain. So I don't mind 475.00 for 10 hp. The C.A.I. was almost as much for 13 hp gain.

My car starts with 400 hp (~320 rwhp L99). That is more than any other car I have ever owned. It probably doesn't need anything. But, just like my brand new 98 Corvette (back in 1998), I began to improve it right away.

[ssmike]

I think we can all agree that shorties don't add much performance. Niether do cat back systems so why is a cat back usually one of the first mods we do? I think it's more sound and looks than performance! We can all also agree that the most bang for the buck for performance is high flow cats. Now that Solo has their cats this can be the only exhaust mod we do keeping stock manifolds and exhaust and gain the most performance with better sound! I have DT shorties, Solo cats and Solo cat back and I'm very pleased, total cost $1450! Love the sound, looks, and performance and I'm probably within 10 HP of LT's, however, I won't have to tune to keep the CEL off like you will with LT's!

[Wilburbeest]

Originally Posted by bi11ymc

I paid less than 475.00 for the DT Shorties shipped!

I dunno, maybe vendors sell them cheaper, $810 is what they cost direct from DT. I've never seen a price for any part vary so much like that but $475 is definitely not near as bad.

Originally Posted by ssmike

I think we can all agree that shorties don't add much performance. Niether do cat back systems so why is a cat back usually one of the first mods we do? I think it's more sound and looks than performance! We can all also agree that the most bang for the buck for performance is high flow cats. Now that Solo has their cats this can be the only exhaust mod we do keeping stock manifolds and exhaust and gain the most performance with better sound! I have DT shorties, Solo cats and Solo cat back and I'm very pleased, total cost $1450! Love the sound, looks, and performance and I'm probably within 10 HP of LT's, however, I won't have to tune to keep the CEL off like you will with LT's!

Like said above to topgun, I'm glad you're happy with your setup and it sounds like you knew exactly what you were doing and it was worth it to you. That's really all that matters. I spent about $500 more than I needed to on my exhaust setup to get stainless headers. That's worth it to me to not have them rust out down the road, seeing as I plan to have this car a very long time (with a 5th gen added after college). I just don't care for what I see as misleading information being spread around, like attributing any significant portion of a 27hp gain with shortys, highflow cats, and a tune to the shortys when both of the other factors are known to give more significant gains. Would I do the same mods? Probably not. I'd probably be more likely to install some LTs, get rid of the cats altogether, have my exhaust guy run some piping with an x-pipe for me and the mufflers of my choice, and call it good. I can totally see why that wouldn't be up everybody's alley though. That's why companies sell multiple products.

[ssmike]

I agree! We're all in a learning curve right now! In a year or 2 we'll all pretty much know what works and what is garbage so new owners will be in a much better postion to get it right the first time and we'll all know what we need to do to take it to the next level! I think we can all agree that we need to take manufacturer claims with a grain of salt and look to real world results to make our purchasing decisions. Till then it takes pioneers like us all to weed out the plethera of products out there to see what works and what doesn't! I applaud the members here who take testing into their own hands and post results!

[Wilburbeest]

Yeah I wish I could be a pioneer with you guys right now but funds are a little thin for that at this point other than looking at what others do and the little bit I already know from results people get with vettes. So I guess I'll have to be one of the people that sucks off the findings of the pioneers instead Believe me though.....I will have my SS.....right after I take over the world