DP testing, the Ruthless Pursuit of Power
10-13-2012, 01:36 AM
#12
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Join Date: 10-30-2011
Location: Eagle Creek, Oregon
Posts: 117
Wednesday night I lowered the air in my 26x9-15 M/T DP's to 16#, with the e-brake pulled tight, spinning the DP's in 1st gear pulls the panel forward dragging the rear tires fast enough I run out of track before I can get the tires hot enough to create any smoke.
10-13-2012, 08:58 AM
#13
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Thread Starter
Join Date: 04-26-2009
Location: City of Champions
Posts: 666
I was spinning with drag radials, slicks hook fine.
With slicks & a 3,000rpm brake boosted launch, (10lbs of boost),
I get 1.8x 60' & 12.5x ET every run now.
I switched out my DP yesterday, to the one 2nd from the right, in the DP picture, in the 1st post.
In this DP I cut open the 1st cat, removed the cat guts, & welded in a piece of 3" tubing, inside of the cat housing. This 3" piece of tubing is not a perfect fit, which is good, as this 1st position cat, is now a resonator. The 2nd cat is a random-tech 100 cell metal matrix, high flow cat.
It should spool quicker, & MPH better, at the track.
It's a little louder now, than with the DP that I took off, which means it flows better.
The DP that I switched out, had the 1st factory cat in place. I bored out the 2nd cat, 2.75",
than welded a piece of perforated 2.75" tubing inside of the cat housing. This turned the 2nd cat into a resonator. Super quiet, & the back pressure from the 1st cat, keep off idle torque high. This DP was good for super off idle street manners, & 12.5s at the track.
This cat worked so well, on & off the track, it was the only DP that I used for 12 straight months.
It is the perfect DP for street, & 12.5s at the track. I'm setting the HHR up for running in the 11s next year. This is the only reason, that I'm doing farther DP testing.
I may only have one more day at the track, before they close for the season.
I'm really thinking that I need the random tech cat in the 1st position, to help create a little
Back pressure, closer to the turbo, to retain off idle torque. Got to test out what I just put on
Now, before even thinking about cutting up, what I have now...
Also, in one of the other DPs in the picture, I have bored a 2.75" hole in both cats. I don't know if the cats will hold up, without falling apart, In the long term. I did test this DP, for a few days, over a year ago, just to see if the cats would hold up, & they did hold up. I really didn't test it for proformance.
With slicks & a 3,000rpm brake boosted launch, (10lbs of boost),
I get 1.8x 60' & 12.5x ET every run now.
I switched out my DP yesterday, to the one 2nd from the right, in the DP picture, in the 1st post.
In this DP I cut open the 1st cat, removed the cat guts, & welded in a piece of 3" tubing, inside of the cat housing. This 3" piece of tubing is not a perfect fit, which is good, as this 1st position cat, is now a resonator. The 2nd cat is a random-tech 100 cell metal matrix, high flow cat.
It should spool quicker, & MPH better, at the track.
It's a little louder now, than with the DP that I took off, which means it flows better.
The DP that I switched out, had the 1st factory cat in place. I bored out the 2nd cat, 2.75",
than welded a piece of perforated 2.75" tubing inside of the cat housing. This turned the 2nd cat into a resonator. Super quiet, & the back pressure from the 1st cat, keep off idle torque high. This DP was good for super off idle street manners, & 12.5s at the track.
This cat worked so well, on & off the track, it was the only DP that I used for 12 straight months.
It is the perfect DP for street, & 12.5s at the track. I'm setting the HHR up for running in the 11s next year. This is the only reason, that I'm doing farther DP testing.
I may only have one more day at the track, before they close for the season.
I'm really thinking that I need the random tech cat in the 1st position, to help create a little
Back pressure, closer to the turbo, to retain off idle torque. Got to test out what I just put on
Now, before even thinking about cutting up, what I have now...
Also, in one of the other DPs in the picture, I have bored a 2.75" hole in both cats. I don't know if the cats will hold up, without falling apart, In the long term. I did test this DP, for a few days, over a year ago, just to see if the cats would hold up, & they did hold up. I really didn't test it for proformance.
Last edited by 2005HHRauto; 10-13-2012 at 12:04 PM.
10-13-2012, 06:44 PM
#15
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Thread Starter
Join Date: 04-26-2009
Location: City of Champions
Posts: 666
It's setup now, & is very consistent.
With this DP, I'll know a lot, with just one trip to the track.
On the street, it does go into 'boost' very easy, compared to the DP, that I have been running. Still pulls the same, on the top end. Maybe the exhaust is too restrictive? I'll know next time out at the track.
10-21-2012, 11:38 AM
#16
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Thread Starter
Join Date: 04-26-2009
Location: City of Champions
Posts: 666
Got a couple of runs in yesterday with the different DP, before the rains came.
The top end was the same, 111+ mph.
Either the exhaust is too restrictive, or that's all it's got.
Maybe it's time for a full 3" exhaust ?
Now off the line, I spun , 1st run I spun more than the 2nd run.
Still got a 12.58 on the 2nd run, with slight spinning off the line.
I was thinking that the track prep might've been bad, combined with a cold track, but, other guys stated that they were hooking fine.
So I'm thinking that the better flowing DP is causing it to super boost at launch.
I lowered the pressure in the slicks, to try to stop the spinning, but the rains came, & the track closed.
Hopefully I'll get to the track one more time before they close for the year.
The top end was the same, 111+ mph.
Either the exhaust is too restrictive, or that's all it's got.
Maybe it's time for a full 3" exhaust ?
Now off the line, I spun , 1st run I spun more than the 2nd run.
Still got a 12.58 on the 2nd run, with slight spinning off the line.
I was thinking that the track prep might've been bad, combined with a cold track, but, other guys stated that they were hooking fine.
So I'm thinking that the better flowing DP is causing it to super boost at launch.
I lowered the pressure in the slicks, to try to stop the spinning, but the rains came, & the track closed.
Hopefully I'll get to the track one more time before they close for the year.
10-26-2012, 06:21 AM
#17
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Thread Starter
Join Date: 04-26-2009
Location: City of Champions
Posts: 666
Well, the track decided to close for the year, more rain is heading this way.
So, since I had that DP out, that I had been running for a whole year, I wanted to see what the remaining 2nd cat 'guts' looked like. I took out the piece of perforated 2.75" tubing, & even with a 2.75' hole in the cat, it was totally intact. And that remaining cat, was still working well, as the piece of perforated tubing , showed signs that it was really being 'cooked'.
Since the free flowing cat was still 'trapping' the same mph, as this DP, & I felt that this DP needs to be tested over the winter, just for the 'fun' of it, to see, if the remaining 2nd cat 'guts' would still hold up, without the support of the 2.75' perforated tubing inside it. Also I still think that this DP, has better street 'manners', than the free flowing DP.
Ok, I did it, I swapped the DP back in, & it's been back in for a couple of days now.
Ok, **** it, this DP is still so much better on the street, than any other DP that I have ever tested. It's a 'keeper', & it's staying back in the HHR...
I really don't see this 1st cat causing a loss of power at the track either, as it's not a NA engine we have here. I'm really thinking, that with the huge ZFR turbo that I will be putting in next year, this DP will 'tame' the beast, as it will help prevent massive boost spikes, & surging issues, by having some 'control'.
The off idle throttle response is so good, & street driving from 0-45 mph, is so much more wonderful, with this DP. It's just so much more pleasant, as a DD with this DP. I still think that the 1st cat, provides a slight amount of back pressure, that is needed for perfect street 'manners'. It's this little amount of back pressure, that is keeping the whole intake 'track', 'charged', so that light throttle response, has instantaneous velocity. And by making the 2nd cat 'free' flowing' with the 2.75" hole in it, makes this DP awesome at the track.
Maybe it's just an 'automatic' trans thing, as the manual guys swear that a free flowing DP is best.
Also guys believe that the stock DP sucks, as they think that it's 'crushed', & restricted, where to O2 sensor is. All that GM did, is create a 'flat' spot, on one side of the DP, to mount the sensor. When the 'die' is pushed againest the piping, to create the flat spot, the surrounding area of the pipe, is expanded, so that there is no restriction.
Seems like a lot of companys want you to believe that the stock DP is crap, so that they can make money. And a lot of guys 'drink' the kool-aid, & buy a lot of these shiny parts...LOL
You will never see any 'real' testing by any of these companys, to prove, that they are better...LOL
So, buy a spare stock DP.
Take 15 minutes, to bore a 2.75" hole threw the 2nd cat, by using a piece of 2.75' tubing, that you can buy for a few bucks at your local auto parts store.
You just lightly push the tubing thru the cat with a back-&-forth motion, with your hands. When your done, you will have a nice, clean, & strong, hole threw the cat, & that 2.75" 'core', will be stuck inside of that piece of tubing.
It's so easy to do, even a 'cave-man' can do it...LOL
I bet that this DP will work better than any other DP you have ever used.
Try it, you'll love it....
So, since I had that DP out, that I had been running for a whole year, I wanted to see what the remaining 2nd cat 'guts' looked like. I took out the piece of perforated 2.75" tubing, & even with a 2.75' hole in the cat, it was totally intact. And that remaining cat, was still working well, as the piece of perforated tubing , showed signs that it was really being 'cooked'.
Since the free flowing cat was still 'trapping' the same mph, as this DP, & I felt that this DP needs to be tested over the winter, just for the 'fun' of it, to see, if the remaining 2nd cat 'guts' would still hold up, without the support of the 2.75' perforated tubing inside it. Also I still think that this DP, has better street 'manners', than the free flowing DP.
Ok, I did it, I swapped the DP back in, & it's been back in for a couple of days now.
Ok, **** it, this DP is still so much better on the street, than any other DP that I have ever tested. It's a 'keeper', & it's staying back in the HHR...
I really don't see this 1st cat causing a loss of power at the track either, as it's not a NA engine we have here. I'm really thinking, that with the huge ZFR turbo that I will be putting in next year, this DP will 'tame' the beast, as it will help prevent massive boost spikes, & surging issues, by having some 'control'.
The off idle throttle response is so good, & street driving from 0-45 mph, is so much more wonderful, with this DP. It's just so much more pleasant, as a DD with this DP. I still think that the 1st cat, provides a slight amount of back pressure, that is needed for perfect street 'manners'. It's this little amount of back pressure, that is keeping the whole intake 'track', 'charged', so that light throttle response, has instantaneous velocity. And by making the 2nd cat 'free' flowing' with the 2.75" hole in it, makes this DP awesome at the track.
Maybe it's just an 'automatic' trans thing, as the manual guys swear that a free flowing DP is best.
Also guys believe that the stock DP sucks, as they think that it's 'crushed', & restricted, where to O2 sensor is. All that GM did, is create a 'flat' spot, on one side of the DP, to mount the sensor. When the 'die' is pushed againest the piping, to create the flat spot, the surrounding area of the pipe, is expanded, so that there is no restriction.
Seems like a lot of companys want you to believe that the stock DP is crap, so that they can make money. And a lot of guys 'drink' the kool-aid, & buy a lot of these shiny parts...LOL
You will never see any 'real' testing by any of these companys, to prove, that they are better...LOL
So, buy a spare stock DP.
Take 15 minutes, to bore a 2.75" hole threw the 2nd cat, by using a piece of 2.75' tubing, that you can buy for a few bucks at your local auto parts store.
You just lightly push the tubing thru the cat with a back-&-forth motion, with your hands. When your done, you will have a nice, clean, & strong, hole threw the cat, & that 2.75" 'core', will be stuck inside of that piece of tubing.
It's so easy to do, even a 'cave-man' can do it...LOL
I bet that this DP will work better than any other DP you have ever used.
Try it, you'll love it....
10-26-2012, 10:15 AM
#19
Senior Member
Thread Starter
Join Date: 04-26-2009
Location: City of Champions
Posts: 666
It passed with no problems...
Also be carefull if your buying a spare factory DP
All Cobalt & HHR SS manuals, use the same DP, the automatic HHR SS DP is different.
So, if you use a manual DP on an automatic HHR SS, the following results:
1. The 1st cat is 'offset' , and is in a very slightly different location.
This cause the DP to , (rest), againest the sway bar, causing alot of rattling.
2. It makes it harder to install the DP, as the 1st cat is hitting againest the sway bar, as your lifting it in place.
3. The O2 sensor location is slightly moved , causing slight interferance with the body, (it's a tight fit), &
your stretching the O2 cable, putting stress on it.
4. The manual DP is exactly .75" shorter, so your exhaust WILL hit & rub, with very litle adjustment available for you to
try & fix it, .75" is a lot, I found out. Now with an aftermarket exhaust, it could be better, or worse.
If you try to put an automatic DP on a manual car, I don't know what problems you eill have.
Also be carefull if your buying a spare factory DP
All Cobalt & HHR SS manuals, use the same DP, the automatic HHR SS DP is different.
So, if you use a manual DP on an automatic HHR SS, the following results:
1. The 1st cat is 'offset' , and is in a very slightly different location.
This cause the DP to , (rest), againest the sway bar, causing alot of rattling.
2. It makes it harder to install the DP, as the 1st cat is hitting againest the sway bar, as your lifting it in place.
3. The O2 sensor location is slightly moved , causing slight interferance with the body, (it's a tight fit), &
your stretching the O2 cable, putting stress on it.
4. The manual DP is exactly .75" shorter, so your exhaust WILL hit & rub, with very litle adjustment available for you to
try & fix it, .75" is a lot, I found out. Now with an aftermarket exhaust, it could be better, or worse.
If you try to put an automatic DP on a manual car, I don't know what problems you eill have.
Last edited by 2005HHRauto; 10-26-2012 at 10:45 AM.
