All I wanted to know is what you meant by this comment.... What is worse about it?
Thank you, thats what I needed in order to understand what you were stating.
The dump systems seem to loose a good bit of power on the dyno and there are very few track numbers to back them up. Most of the vendors have realized this, or they would all be running DP's with dumps on them. 90
% of the fast cars here on the forums have at least 4 feet of exhaust after the turbo, there is a reason for this and I hope I don't have to point it out.
The see or dump systems that exit near the rear pass compartment have proven track times with more then there fair share of results over the DP dumps that are on the market. Does that make sence?
Brian the earlier post was a little hostile because you seem to be following me and my posts. If you track your posts outside the NW 1/2 of them seem to be right after what I have to say. I would have to say its border line harrasment but I think your a better person then that, then again maybe not. Either way... sorry for jumping your shit earlier on.
Thank you, thats what I needed in order to understand what you were stating.
The dump systems seem to loose a good bit of power on the dyno and there are very few track numbers to back them up. Most of the vendors have realized this, or they would all be running DP's with dumps on them. 90
% of the fast cars here on the forums have at least 4 feet of exhaust after the turbo, there is a reason for this and I hope I don't have to point it out.
The see or dump systems that exit near the rear pass compartment have proven track times with more then there fair share of results over the DP dumps that are on the market. Does that make sence?
Brian the earlier post was a little hostile because you seem to be following me and my posts. If you track your posts outside the NW 1/2 of them seem to be right after what I have to say. I would have to say its border line harrasment but I think your a better person then that, then again maybe not. Either way... sorry for jumping your shit earlier on.
Actually, if you would, could you point out why? Some of the custom fabricated, fast as hell SRT's I can think of how no where near 4ft of pipe on them. I truly don't see how a dump would hinder performance on a forced induction motor...
As for my posting habits, I just surf the active list. You are what, in the top three for all time posts? I bet a lot of people appear to be posting after everything you say. If I wanted to harass you, there would be no question whether i was doing so or not
Actually, if you would, could you point out why? Some of the custom fabricated, fast as hell SRT's I can think of how no where near 4ft of pipe on them. I truly don't see how a dump would hinder performance on a forced induction motor...
As for my posting habits, I just surf the active list. You are what, in the top three for all time posts? I bet a lot of people appear to be posting after everything you say. If I wanted to harass you, there would be no question whether i was doing so or not
Actually the top 8 of the top 10 fastest here on the forums have mid length exhaust on them. I don't see how the dump DP's don't work either but there are several that have stated lost power on the dyno with them. Try a search and see what you come up with. The only thing I can come up with is the exhaust pulses are still moving for and aft with that short of a dump on it. Temp vs exhaust gas velocity? At this point I would simply be guessing but we have tried it on 4 different cars with a short dump then a longer dump, all the longer dump cars made more power then the short dump and pulled harder in the 1/4 mile with better numbers. Why, no idea. Does longer work for our car, yes proven by more then just one vendor.
Actually the top 8 of the top 10 fastest here on the forums have mid length exhaust on them. I don't see how the dump DP's don't work either but there are several that have stated lost power on the dyno with them. Try a search and see what you come up with. The only thing I can come up with is the exhaust pulses are still moving for and aft with that short of a dump on it. Temp vs exhaust gas velocity? At this point I would simply be guessing but we have tried it on 4 different cars with a short dump then a longer dump, all the longer dump cars made more power then the short dump and pulled harder in the 1/4 mile with better numbers. Why, no idea. Does longer work for our car, yes proven by more then just one vendor.
I ran a 11.56 open and a 11.7 closed. Same night, same tune, same 1.67 60'
Open I made 30psi, closed I only made 27-28. The only reason I closed it up was because at PIR you can't run past 10pm if you are above 90db... which I was closed too, but oh well. The reason 8 out of 10 of the fastest cars run a mid length system is because of twin scroll turbo's and their need for a little bit of back pressure to keep the pulses separate. Also, open raises your egt a lot... not sure why, but it does.
I think a reason people loose power on open dump with stock turbo is you are spinning the turbo up too soon. You get the spike sooner then with the stocker its all down hill. who knows.
now, this may not be true of all setup's. And my tune was done with the cutout open. So theoretically the car should run best at that boost level.
I think with a dbb turbo or something that spools faster the lack of back pressure might hurt the turbo but for me the faster spool from no back pressure makes for better times at the track.
also, something worth more than .2 off the time is the fireballs coming out from under my car.
now, this may not be true of all setup's. And my tune was done with the cutout open. So theoretically the car should run best at that boost level.
I think with a dbb turbo or something that spools faster the lack of back pressure might hurt the turbo but for me the faster spool from no back pressure makes for better times at the track.
also, something worth more than .2 off the time is the fireballs coming out from under my car.
Good point, I didn't think of the tuning aspect of it....
I ran a 11.56 open and a 11.7 closed. Same night, same tune, same 1.67 60'
Open I made 30psi, closed I only made 27-28. The only reason I closed it up was because at PIR you can't run past 10pm if you are above 90db... which I was closed too, but oh well. The reason 8 out of 10 of the fastest cars run a mid length system is because of twin scroll turbo's and their need for a little bit of back pressure to keep the pulses separate. Also, open raises your egt a lot... not sure why, but it does.
I think a reason people loose power on open dump with stock turbo is you are spinning the turbo up too soon. You get the spike sooner then with the stocker its all down hill. who knows.
There are a few more variables also. ( I wasnt there correct me if I'm wrong checksum)
1. Car had a lot more runs on it by 10pm when you closed the dump.
2. I dont remember but after your dump I think you said your exhaust system chokes down a little (might be wrong)
3. dump closed exhaust has to run through a few more bends.
4. As you already stated Tune.
I honestly think it has 100% to do with fitting the proper parts together. Basically what works best for your set up.
That being said I am a big fan of the dump on turbo charged vehicles but again its not best for all set ups. I would be verry interested in doing a test of an open dump connested to an exhaust that goes straight back and dumps under passenger section. See different dyno number/track numbers.
"***I would also like to add this note. Exhaust pipe doesnt always equal back pressure. ***"
I remember being told that "a properly designed exhaust will actually pull away from the turbo." Again this was told to me by Turbo deisel builders for some reason I believe them because they have slips and dynos and spent the time and money to do it 100 wrong ways first.
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ATTN : Everything said on the forums is 80% truth at BEST
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Just out of curiosity who are the 10 fastest? I havent looked at the timeslip database since I was knocked off the list. I try looking now but it seems to be down for a while.
Just out of curiosity who are the 10 fastest? I havent looked at the timeslip database since I was knocked off the list. I try looking now but it seems to be down for a while.
* until chuck round house kicks him for getting in his kool aid.
Have had a see for along time. No troubles with cops or otherwise. Dyno'd 8 hp higher over a 3" turbo back but different days, temps, blah. Same dyno thou.
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Quote: Originally Posted by Alpha-Omega
I have always said god is overrated and thats it ok to be gay. I experimented in college and can say from experience its not bad.
I ran a 11.56 open and a 11.7 closed. Same night, same tune, same 1.67 60'
Open I made 30psi, closed I only made 27-28. The only reason I closed it up was because at PIR you can't run past 10pm if you are above 90db... which I was closed too, but oh well. The reason 8 out of 10 of the fastest cars run a mid length system is because of twin scroll turbo's and their need for a little bit of back pressure to keep the pulses separate. Also, open raises your egt a lot... not sure why, but it does.
I think a reason people loose power on open dump with stock turbo is you are spinning the turbo up too soon. You get the spike sooner then with the stocker its all down hill. who knows.
Thanks Eric for the input but wanted to point out a few things.
You lost boost becaue why? Your tune was for the open cut out not closed (expecting this to drop your power levels and times at the track).
Now with that said a more equal compairison would have been to have a mid pipe dump system on your car tune it for that then open the dump. Then we could see that the dump kills some power.... get my point. The car was tuned for the open dump and when you close it you have to go through what? An exhaust system, if it had been a mid pipe dump system and it lost power, I would say "right on" because that would be real world testing. Maybe you are running a mid pipe dump system, no idea.
The twin scroll is true to a point. The standard non twin scroll turbos also respond very well to mid pipe dump systems. The SST really wakes up if you have a dump in the DP but you get ever better results if you put a mid pipe dump system on a car with one. I can not speak for all the different turbo set ups on the market just what I have worked with and what we have found with our set ups is that a mid pipe system works much better then a dump DP.
* until chuck round house kicks him for getting in his kool aid.
Have had a see for along time. No troubles with cops or otherwise. Dyno'd 8 hp higher over a 3" turbo back but different days, temps, blah. Same dyno thou.
We have been on a dyno with a 3" exhaust system and then unhooked it at the first bend, picked up the exact same numbers, 8WHP. Then unhooked it at the DP, lost 13.
I talked to my tuner Bobby today. He said that the tune was actually done with the cutout CLOSED because the dyno wideband can't hook up in the cutout and has to be hooked to the tailpipe. So the car was actually tuned with it closed. The exhaust system I have is 3" custom that follows the stock track not a straight pipe. It has a large "cherry bomber" but no other mufflers.
Car tuned on a closed system made 440hp/510tq at 27psi. Open dump run with no change to the tune made 465hp/495tq. so I picked up 15hp and lost 15tq at 29psi.
As for the runs later in the night, after I closed the dp I made 2 more runs in the loud lane before going home for the night, one was 11.6 the other was 11.7 with a bad 60.
for the setup I was running, I think the open dump helped, but for the setup I am going to I will be running a midpipe.
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