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Just seeing if any of you guys would be interested, that are still running the Greddy setup.
These were released a few months back through SPMS, same company doing billet gears, valve covers, and Greddy replacement tubular manifolds.
Here's a pic of the set. No install pics yet, from what I've seen.
Im extremley interested!! But I didnt see the kit on their website, where can I buy it? Any chance of 3in downpipes in the near future? Im hoping it's for the 18g kit....
My pass side pipe did not fit after waiting 2 months for them. This should be cleared up by now for you guys. Jeremiah replaced the welder recently because of the experience I had. jeremiah was out of town and his welder kept me waiting for months.
Check out their facebook page. I would be comfortable ordering through them again because Jeremiah was helpful and communicative throughout the process. What I experienced was not standard for them so Jeremiah the owner made a managerial decision to replace his fabricator.
I went from 443/393@12.5PSI to 470/430@11psi by adding these pipes and a larger catback. Highly recommended.
My pass side pipe did not fit after waiting 2 months for them. This should be cleared up by now for you guys. Jeremiah replaced the welder recently because of the experience I had. jeremiah was out of town and his welder kept me waiting for months.
Check out their facebook page. I would be comfortable ordering through them again because Jeremiah was helpful and communicative throughout the process. What I experienced was not standard for them so Jeremiah the owner made a managerial decision to replace his fabricator.
I went from 443/393@12.5PSI to 470/430@11psi by adding these pipes and a larger catback. Highly recommended.
Thanks! So you kept the greddy 2.25in (or somewhere around there) down pipe, and then used a 3in downpipe attached to the greddy and it still made that big of a difference? Interesting, I always assumed id need a 3in pipe connected straight to the turbo..
Thanks! So you kept the greddy 2.25in (or somewhere around there) down pipe, and then used a 3in downpipe attached to the greddy and it still made that big of a difference? Interesting, I always assumed id need a 3in pipe connected straight to the turbo..
If you're going for built block numbers I would say to try to find a 3" setup from the turbo just for peace of mind. I haven't read up to see the results of others with the 3" greddy one piece downpipes just yet. I always consider the fact that the dump tubes effectively increase your exhaust's diameter when you need it most, so 3" downpipes were unnecessary for my current power goals. Even for my next of 650whp I believe.
But yes I just have the 2.25" going into a 3" catback. All resonator style, open straight thru mufflers. The test pipes you see are actually also 2.25" ID, not 3". I will consider swapping those out for some 3" ones for next round, and I will probably keep the greddy cast pipes that hook directly to the turbo too since they are so short. I don't know how much restriction they are really adding because of their short length.
The relocation pipes reduce a serious amount of turbulence in the exhaust pipes. I think you would see much smaller gains going from 2.25" downpipes to 3" downpipes (both with dump tubes)comparing to going from 2.25" downpipes without dump tubes to 2.25" downpipes with dump tubes.
If you're going for built block numbers I would say to try to find a 3" setup from the turbo just for peace of mind. I haven't read up to see the results of others with the 3" greddy one piece downpipes just yet. I always consider the fact that the dump tubes effectively increase your exhaust's diameter when you need it most, so 3" downpipes were unnecessary for my current power goals. Even for my next of 650whp I believe.
Thats what I thought, but then a 3" pipe would be too big to mount directly to the turbo, unless it tapered down to 2.25" at the turbos? I think; Im not 100% sure. But if what I just said is true, then wouldn't the greddy cast downpipe + a 3" downpipe be just as good? Possibly better since you wouldn't have to fab bungs for the o2 sensors.
I have a built block, modded turbos, etc. and plan on reaching somewhere in the 700-800 whp range. As of now, the exhaust system is the only thing left to figure out. Might just throw a 45 degree angle on the test pipes to direct the exhaust downward and call it good.
Anyways, the waste gate kit looks great! Reminds me of the one that comes with the Greddy tuner kit. Found some pictures for comparison:
I think the straight one piece 3 inch tapered downpipe would be better purely because of turbulence caused by the old wastegate bung and blanking flange combination. It definitely looks like those greddy three inch one piece pipes are tapered down like you thought.
I found this photo from another post here which will shed some light. It's even smaller than you thought. The entire machined face is only about 2.625" diameter. That hammers home the turbulence thing even further. This is the point where the exhaust gases will be at their highest velocity (ignoring anything upstream) so anything to keep them moving will mean more scavenging and more power I believe.
Negligible? Probably at 500 hp, probably not where you're shooting
I'm going to be building these 3" down pipes over the winter to mimic the AAM 3" greddy downpipe - I'll post my progress on my build page.
I'll be using a 2" to 3" reducer(expander) straight off the turbos and going to a 3". Stainless 3" to my 4" aluminum.
I literally just spent ~3 hours researching and typing a response, only to have my browser quit unexpectedly. So let me try again, it may be a little more brief this time around.
I was thinking about using an expander(s) in the same fashion as you, but I was worried about the 2" choke point. I have no idea how restrictive that would make the downpipe; but it seems like it'll be a pain to convert from a 2" to anything over 3" (that would be so many adapters?). Plus you would have to get all the way up to your final diameter in a short distance (to reduce restriction, right?) all while trying to make all the proper bends. Would you use straight adapters or cones? Aren't you worried going all the way to a 4" diameter might be too big for our small turbos? Im not saying 4" is too big, just trying to gather some info before deciding on my downpipes. I have found it rare to see anyone running 3.5" on here, and even more so with 4". 3" seems to be the standard. I did find this though, a 4" catback mounted to a 5" downpipe helping to produce ~1000whp: http://www.superstreetonline.com/fea...p-nissan-350z/ Im trying to figure this all out as well. Here's some stuff I found, hopefully it helps, or leads to someone correcting me before I go with the wrong setup.
Anyways, I have done some digging around and found this article comparing various combos of 3" (recirculating) and 3.5" (open dump) downpipes and catback exhausts on a supra (not sure how it equates to the vq platform, but the general principle has to be the same?): http://www.superstreetonline.com/how...ust-test-tech/
The end result declared the 3.5" full exhaust winner, making a whopping 103whp gain over the original 3" full exhaust. On top of the whp gain, the turbo spooled quicker, and had a deeper note (not totally related to hp gains, buttt who doesn't like a nice, deep, rumbling exhaust note?).
This is making me lean more toward a 3.5" downpipe and/or a 3.5" catback (I most likely will just attach a 45 degree piece on the end to direct exhaust gasses to the ground and call it good.) The 3.5" would have a ~142% gain in volume (~216% if you went with the 4") over the 2.25" downpipes included in the kit + testpipes (~78% gain with 3" test pipes over 2.25"). Which once again may be too big for small turbos? I mean a ~140-220% increase in volume over stock (greddy) is pretty substantial, but then again, since the pipes that come with the kit are restrictive, I'm not sure what enviornment these turbos were engineered to flow the most efficiently in. A chart showing how much air these turbos are capable of moving would be helpful. There is probably a way to calculate which volume would allow for the turbo to flow the most freely based on how much air the turbo can move. Sounds like physics, thermodynamics, and turbulence understanding would all be needed to do that though, and frankly, I dont have that kind of knowledge. Experimenting in different expansions/reductions throughout the exhaust system may force the air out quicker than an open exhaust? Or create backpressure...
Well theres my 2 cents (along with a bit of rambling )...
Last edited by louisville13; 10-21-2017 at 02:22 AM.
I literally just spent ~3 hours researching and typing a response, only to have my browser quit unexpectedly. So let me try again, it may be a little more brief this time around.
I was thinking about using an expander(s) in the same fashion as you, but I was worried about the 2" choke point. I have no idea how restrictive that would make the downpipe; but it seems like it'll be a pain to convert from a 2" to anything over 3" (that would be so many adapters?). Plus you would have to get all the way up to your final diameter in a short distance (to reduce restriction, right?) all while trying to make all the proper bends. Would you use straight adapters or cones? Aren't you worried going all the way to a 4" diameter might be too big for our small turbos? Im not saying 4" is too big, just trying to gather some info before deciding on my downpipes. I have found it rare to see anyone running 3.5" on here, and even more so with 4". 3" seems to be the standard. I did find this though, a 4" catback mounted to a 5" downpipe helping to produce ~1000whp: http://www.superstreetonline.com/fea...p-nissan-350z/ Im trying to figure this all out as well. Here's some stuff I found, hopefully it helps, or leads to someone correcting me before I go with the wrong setup.
Anyways, I have done some digging around and found this article comparing various combos of 3" (recirculating) and 3.5" (open dump) downpipes and catback exhausts on a supra (not sure how it equates to the vq platform, but the general principle has to be the same?): http://www.superstreetonline.com/how...ust-test-tech/
The end result declared the 3.5" full exhaust winner, making a whopping 103whp gain over the original 3" full exhaust. On top of the whp gain, the turbo spooled quicker, and had a deeper note (not totally related to hp gains, buttt who doesn't like a nice, deep, rumbling exhaust note?).
This is making me lean more toward a 3.5" downpipe and/or a 3.5" catback (I most likely will just attach a 45 degree piece on the end to direct exhaust gasses to the ground and call it good.) The 3.5" would have a ~142% gain in volume (~216% if you went with the 4") over the 2.25" downpipes included in the kit + testpipes (~78% gain with 3" test pipes over 2.25"). Which once again may be too big for small turbos? I mean a ~140-220% increase in volume over stock (greddy) is pretty substantial, but then again, since the pipes that come with the kit are restrictive, I'm not sure what enviornment these turbos were engineered to flow the most efficiently in. A chart showing how much air these turbos are capable of moving would be helpful. There is probably a way to calculate which volume would allow for the turbo to flow the most freely based on how much air the turbo can move. Sounds like physics, thermodynamics, and turbulence understanding would all be needed to do that though, and frankly, I dont have that kind of knowledge. Experimenting in different expansions/reductions throughout the exhaust system may force the air out quicker than an open exhaust? Or create backpressure...
Well theres my 2 cents (along with a bit of rambling )...
After taking classes and practicing all of these things and more in the engineering field we still follow the KISS method: Keep-it-simple-stupid.
You want low restriction to create a greater pressure differential between the exhaust manifold and turbine outlet. You also want a properly tuned exhaust system. This means the appropriate length (volume as result given diameter fixed) to induce optimum scavenging; further increasing the average pressure differential to provide optimum turbine thrust.
There is more than one length that will provide proper scavenging, this can be examined experimentally using a crayon or wax pen... Motorcycle guys do this. You draw a line lengthwise down the exhaust, and start the engine, run wot. Examine where it melts first. These hot spots are antinodes of the sine wave produced by the detonation. They will occur evenly spaced down the length of the exhaust... Pick one and cut.
I'm not sure if we have the luxury that bikes do though, since our exhaust has to be a specific length for the most part. I believe that's where things like what ART employed come in; resonance chambers etc.
That being said you mentioned wanting a nice deep exhaust note, but if you only ran downpipes it would be so freaking obnoxiously loud lol and you would be breathing in a bunch of exhaust fumes and noxious gasses.
Go for the 3.5" catback with some big azz test pipes! Who doesn't love shooting flames out of a single exit?? This is a 4" tip on mine:
After taking classes and practicing all of these things and more in the engineering field we still follow the KISS method: Keep-it-simple-stupid.
You want low restriction to create a greater pressure differential between the exhaust manifold and turbine outlet. You also want a properly tuned exhaust system. This means the appropriate length (volume as result given diameter fixed) to induce optimum scavenging; further increasing the average pressure differential to provide optimum turbine thrust.
There is more than one length that will provide proper scavenging, this can be examined experimentally using a crayon or wax pen... Motorcycle guys do this. You draw a line lengthwise down the exhaust, and start the engine, run wot. Examine where it melts first. These hot spots are antinodes of the sine wave produced by the detonation. They will occur evenly spaced down the length of the exhaust... Pick one and cut.
I'm not sure if we have the luxury that bikes do though, since our exhaust has to be a specific length for the most part. I believe that's where things like what ART employed come in; resonance chambers etc.
That being said you mentioned wanting a nice deep exhaust note, but if you only ran downpipes it would be so freaking obnoxiously loud lol and you would be breathing in a bunch of exhaust fumes and noxious gasses.
Go for the 3.5" catback with some big azz test pipes! Who doesn't love shooting flames out of a single exit?? This is a 4" tip on mine:
Im so glad you know as much about the science behind the topic! I was becoming a bit hopeless haha. Anyway, as far as wanting the deep exhaust note, I have gone way over budget on my build already. Meaning a quaility exhaust system is out of budget. Which leaves me with the choice of no exhaust or having a muffler shop just straight pipe it (still have to figure cost). Regardless, Im going to have to have downpipes fabbed, adding to the cost. This is the main reason ill most likely run open downpipes (to begin with atleast).
How did you plan on making a 2"-4" downpipe? I dont have a ton of fab experience but it still seems like itd be pretty difficult. Also, i hadnt realized that you were talking about a single exit 4" exhaust, i assumed it would be true dual (ive been told stick with dual?). That makes alot more sense now, giving you two turbos to flow through one 4" pipe rather then one turbo flowing a 4" pipe alone.
That thing is massive! Youre going to be melting youre bumper off for sure haha but its going to look/awesome!
Last edited by louisville13; 10-21-2017 at 08:56 AM.
I literally just spent ~3 hours researching and typing a response, only to have my browser quit unexpectedly. So let me try again, it may be a little more brief this time around.
Thanks for taking the time - I appreciate your opinion and insight...I typically hit the submit button and then go back and edit my post to 'autosave'...
Originally Posted by louisville13
I was worried about the 2" choke point. I have no idea how restrictive that would make the downpipe
We may be talking about different things but the outlet on the exhaust housing is (I believe) just under 2inches, the turbine is 50mm (2")...I would eliminate the o2sensor housing that comes off the turbo and connects to the testpipe/cat ... so having a very short section of 2" right before it bubbles up to 3" ... They sell 2" to 3" reducers - I wouldnt fab it up myself. I'm not too worried about it and I dont think it'll be a choke point.
Originally Posted by louisville13
Would you use straight adapters or cones? Aren't you worried going all the way to a 4" diameter might be too big for our small turbos?
I may not be coming across - but my 3' down pipe would incorporate the Y pipe where it'd connect to a single 4" exhaust ... the 4" exhaust is already fabricated/built/installed - see my build post if you're interested.
Originally Posted by louisville13
Would you use straight adapters or cones? Aren't you worried going all the way to a 4" diameter might be too big for our small turbos?
too big? Homeboy Corky Bell is quoted saying back pressure is the enemy of FI
Originally Posted by louisville13
I have found it rare to see anyone running 3.5" on here, and even more so with 4". 3" seems to be the standard.
Not many options anything bigger than 3" ... I sourced 12 feet of 4" Al and a 4" vibrant muffler.
Originally Posted by louisville13
3.5" full exhaust winner, making a whopping 103whp gain over the original 3" full exhaust. On top of the whp gain, the turbo spooled quicker, and had a deeper note (not totally related to hp gains, buttt who doesn't like a nice, deep, rumbling exhaust note?).
not surprising...
Originally Posted by louisville13
This is making me lean more toward a 3.5" downpipe and/or a 3.5" catback (I most likely will just attach a 45 degree piece on the end to direct exhaust gasses to the ground and call it good.)
3.5 may be excessive (but who am I to say this!)
I bought a 8 sticks of 45 degree bends and I think I can make everything with these pre-bent stainless sticks.
I'm installing a v-band just past the first 45* so If I am at an event, I can disconnect the exhaust and have them run open. I'm also (should be a surprise) running a small flex hose on the 3" down pipe and then a 4" on the exhaust - give the system room to expand/contact and also give me a little tolerance during the fabrication process.
Originally Posted by louisville13
The 3.5" would have a ~142% gain in volume (~216% if you went with the 4") over the 2.25" downpipes included in the kit + testpipes (~78% gain with 3" test pipes over 2.25"). Which once again may be too big for small turbos? I mean a ~140-220% increase in volume over stock (greddy) is pretty substantial
Be careful with these calculations ... many things go into flow but it should be noted that flow isnt proportional or linear with respect to cross-sectional area.
Double the cross-sectional area doesnt mean double the flow - usually its more but there are many factors to this. I'm sure there's a online calculator to figure this.
Originally Posted by yosip1115
There is more than one length that will provide proper scavenging, this can be examined experimentally using a crayon or wax pen...
great example
Originally Posted by yosip1115
but if you only ran downpipes it would be so freaking obnoxiously loud
I wear ear plugs ... granted I don't have an interior/sound deadening
Thank you for answering all these questions for me. Your format was much cleaner than they way I have been posting so Im going to steal it for a sec haha
Originally Posted by bealljk
We may be talking about different things but the outlet on the exhaust housing is (I believe) just under 2inches, the turbine is 50mm (2")...I would eliminate the o2sensor housing that comes off the turbo and connects to the testpipe/cat ... so having a very short section of 2" right before it bubbles up to 3" ... They sell 2" to 3" reducers - I wouldnt fab it up myself. I'm not too worried about it and I dont think it'll be a choke point.
My mistake, through all the seating I have done I haven't been able to find anything that expands/reduces by more than .5". Could you send me a link please? Or better yet fab me up a set of downpipes when you do yours since I'll have to find a fabricator anyways (the shop I worked at/can go back and use only did structural steel).
I may not be coming across - but my 3' down pipe would incorporate the Y pipe where it'd connect to a single 4" exhaust ... the 4" exhaust is already fabricated/built/installed - see my build post if you're interested.
Yea, I read that wrong. I thought you were trying to 2" to a 4" dual exhaust. This way makes much more sense. What is your power range? Im shooting for mid 700's , don't know if a 4" would be necessary for me or not. And I'm definitely going to check out your build thread just as soon as I finish this reply!
too big? Homeboy Corky Bell is quoted saying back pressure is the enemy of FI
This is when I thought you were doing a dual exit exhaust. I know backpressure is the enemy of FI, but theres a correlation between diameter/length and velocity (I assume?). If the diameter is too large and the length is too long the gasses would slow down/become denser toward the end ; making the turbos have to work harder to force out the exhaust --> backpressure. Which i am sure you already knew (if its true) and calculated all this on your system because you seem to know exactly what you're doing, more so than I anyways.
Which I could be wrong about since I have never learned anything even remotely related to physics/thermal dynamics/whatever other info is needed for all this ha.
Not many options anything bigger than 3" ... I sourced 12 feet of 4" Al and a 4" vibrant muffler.
Man I would kill to have a shop with all the machinery/tools needed to be able to do this.
I'm installing a v-band just past the first 45* so If I am at an event, I can disconnect the exhaust and have them run open. I'm also (should be a surprise) running a small flex hose on the 3" down pipe and then a 4" on the exhaust - give the system room to expand/contact and also give me a little tolerance during the fabrication process.
Be careful with these calculations ... many things go into flow but it should be noted that flow isnt proportional or linear with respect to cross-sectional area.
Double the cross-sectional area doesnt mean double the flow - usually its more but there are many factors to this. I'm sure there's a online calculator to figure this.
I used an online calculator to figure this out, as its a bit out of my comfort zone (I'm in school for bio; math is my enemy). The numbers don't mean much to me, just posted them because someone might be able to use them.
Only now am I realizing that there are 2 other people replying in this thread, not one. So all my typing up until now (previous posts included) I accidentally combined info gathered (on goals, builds, opinions, etc.) from you and yosip1115. My bad.
I wear ear plugs ... granted I don't have an interior/sound deadening
As long as I won't go deaf with an oem cabin (trying to make the car appear as stock as possible so I can hurt some feelings on the street) then I have no problem running open downpipes for a bit until I rack up some more cash.
Since both of you seem to have a firm grasp on the factors playing into this; any input on a 3.5" downpipe vs 3" downpipe with open wastegate dump? I am not sure what I will end up going with, an open dump wastegate is the only thing I am 100% sure on. I am now contemplating 3" dp to single exit 4" exhaust, 3" dp to 3.5" exhaust, or 3.5" dp to 3.5" exhaust. But maybe a single exit in a different size would be better than the true dual? Ughhh so many different combo's available and I have already been typing/researching this reply for an hour and 50 mins (seriously where does the time go!?). So no time to reread and edit, and ill have to do more research later.
All the input I have been receiving is greatly appreciated and very helpful.
02-08-2017, 09:51 AM
Greddy wastegate relocation kit
So let me try again, it may be a little more brief this time around.
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