Ok, I'm looking at doing a complete downpipe back 3" exhaust and I'm going to test exhaust backpressure.  I figure I'm going to take readings  with the stock exhaust, 3" exhaust, and with no exhaust(only downpipe).  I'm going to measure the backpressure at the O2 bung in the turbo as I'm curious to see if there is any difference in the backpressure with the differenct combinations.  I'm just wondering if anyone has any recommendations for what to use to measure the backpressure(I'm thinking a regular boost gauge plumbed to where the O2 sensor bung is in the turbo).  I haven't really looked around at what to use yet as I'm not done with the 5 speed swap, but I'm going to be done this weekend if I can get my clutch hydralics to stop leaking(damn accumulator removal) :evil:

Quote from: skalorOk, I'm looking at doing a complete downpipe back 3" exhaust and I'm going to test exhaust backpressure.  I figure I'm going to take readings  with the stock exhaust, 3" exhaust, and with no exhaust(only downpipe).  I'm going to measure the backpressure at the O2 bung in the turbo as I'm curious to see if there is any difference in the backpressure with the differenct combinations.  I'm just wondering if anyone has any recommendations for what to use to measure the backpressure(I'm thinking a regular boost gauge plumbed to where the O2 sensor bung is in the turbo).  I haven't really looked around at what to use yet as I'm not done with the 5 speed swap, but I'm going to be done this weekend if I can get my clutch hydralics to stop leaking(damn accumulator removal) :evil:

Great idea, you got to have some hard data for yourself and for your efforts and $$ invested, it?s a better feeling when you have confirmed results.  The toughest part you will find is trying to match the 18mm threads of the o2 hole to some form of vacuum line/boost port.  A good suggestion is to get a threaded o2 cap plug (I bought some from Motec, there are others), drill a hole in the middle of it, tap it for a something that will extend the attachment for the rubber vacuum line far enough away so the vacuum line won?t melt when testing the pressures.  Maybe thread for something like a small 1/4 or 3/16 metal pipe as used for water lines or gas lines in building applications, then an adaptor for a brass vacuum fitting, not that odd of animals that can be had at any hardware store.  Make sure you maintain a consistent boost reading when running the tests, shoot for something like 10 psi max all the time as rpm changes will be enough to make the BP values change, I used a manual boost controller (I have a box of these) starting at 5 to 6 psi slowly/carefully increasing to a 10 psi test setting.  Then once I had a steady 10 psi, attached the vacuum line to the BP port and ran it to an identical engine boost gauge so there were not variations between the 2 gauges I used, and only the differences being tested for.  I have 4 boost gauges and 2 were within ? psi from 0-25 psi so I used and mounted those. Since you will be reading before the turbo/stock o2 hole, there will be some pretty high readings mostly as rpms climb, somewhere in the range of 30 psi at the higher rpms, the value to shoot for/hope for is 20 psi with 10 psi of boost or a 2:1 ratio, less is better but not easy to get to with any stock turbo engine setup. Of course your ECM will wonder what happened to the o2 sensor?s reading, but with mine I had already drilled and tapped another hole in the downpipe for a wide-band o2 sensor so that hole was available for the ECM?s o2 while running these tests, or just shut off the o2 closed loop operation for these tests.

Good luck, hope this helps :) !

Jeff M

Wow, I didn't even think about a boost gauge.  I figured it would be more involved than that, but hell, it's all the same animal.  While on the subject, (I guess we will see when you get the readings done)  A dump pipe would provide the lowest pressure, but is it really THAT much lower?  Black Sunshine (AKA Strip Duty) will have nothing other than performance in mind.  Open DP is no problem for me.  I'm running str8 exhaust as it is, but if I can reach 2:1 or lower w/ an open downpipe and the Disco Potato, then it's ON!!!  I've been thinking about just saying screw it and buying the Potato so I have to install it.   :twisted:  It only takes me 2 weekends of O/T to afford it, so maybe I should do it while I can.  Then make up a custom 3" DP and dump it right behind the driver side front wheel.  I should sound like a Cummins w/ open exhaust huh?

Quote from: god910Wow, I didn't even think about a boost gauge.  I figured it would be more involved than that, but hell, it's all the same animal.  While on the subject, (I guess we will see when you get the readings done)  A dump pipe would provide the lowest pressure, but is it really THAT much lower?  Black Sunshine (AKA Strip Duty) will have nothing other than performance in mind.  Open DP is no problem for me.  I'm running str8 exhaust as it is, but if I can reach 2:1 or lower w/ an open downpipe and the Disco Potato, then it's ON!!!  I've been thinking about just saying screw it and buying the Potato so I have to install it.   :twisted:  It only takes me 2 weekends of O/T to afford it, so maybe I should do it while I can.  Then make up a custom 3" DP and dump it right behind the driver side front wheel.  I should sound like a Cummins w/ open exhaust huh?

Yea BABY!!! :twisted:   There was someone else who did grow a potato on his TGP  :lol: (TGP?, I think maybe even Skalor?) and that was a little while ago, still no reply to how well it worked let alone before and after tests such as back pressure, or outlet air temps of the turbo/intercooler with this more efficient design.  Though these new Garretts are more for the masses of 4 cylinders evident by looking at some of the bigger 400hp plus version, still having a T25 flange, don?t know for sure if these are best when feed a 3.1L motor?s exhaust verses all those 1.6-1.9L Hondas exhaust (some larger but not many near a long intake runner 3.1L).  But it?s better for sure, the turbine wheels have the most research into them, mainly to get them to spin much better with the exhaust its given/small amounts from a little 4 cylinder, but we have an abundance of exhaust from our engines so hope these wheels don?t cause any BP problems for us on their own, maybe slight, maybe little more than ideal, tests will tell 8) !

So, see you in a few weeks when your OT is done :D .

Jeff M.

Unfortuneately, I don't have a disco potato at this point in time.  I'm looking to get one come summer, but the T-25 stays for now as I'm curious to see what it can do.  I do think that the potato is the best suited bolt-in upgrade that is available at a decent price(under $1000 now!).  I think that the bigger turbine housing will help us with lowering our exhaust backpressure and the potato's exhaust wheels are designed with more flow in mind(there are less blades on the turbine than previous wheels).  There are a couple guys out there that may go this route and I think it will be a good choice. I just don't have the money right now to get one and I already have a lot going on with my TGP than to add more stuff into the mix. :P


Jeff, that's a good idea about the O2 plug as I didn't think about that.  I'm just going to make my own adapter as I kinda work in a machine shop and we have 2 mills, 1 cnc, and one lathe.  So, I can basically make anything that I could ever need/want.  Anyways, I figure it's about time that we get some hard data to work with as that's the only thing that's going to help us get anywhere.  I'm really hoping to see a significant decrease in backpressure as the stock exhaust looks restrictive.  I really would like to make a bigger downpipe, but there are space restrictions that I'm not ready to deal with at this point so the stock downpipe stays for now.   :evil:

What are our options when we are talking about air temps?  I will update more later, but I am building a computer for the car.  So, I will be able to do a whole lot w/ it.  I would love to stick different temp sensors in the intake/exhaust tract to monitor and gain from those readings.  I am thinking:
1) before turbo
2) after turbo/ before I/C
3) after I/C
4) Just before T/B (or will the sensor in the upper plenum be close enough to upper I/C that it will be the same?)
Also, being as the I/C and T/B are so damn close I could get rid of #3 and just put it right before the T/B to get a better idea of how cool it STAYS after the I/C.

Then on the exhaust side, all you really need is manifold exit temps and post turbo temps correct?  Will you even be able to get exact manifold temps due to the log manifold?  I doubt it, being as it's not a diesel, and we can't really tune fuel per cylinder are exh. temps even an issue?  So, Jeff, what are you using to measure air temps?

Great, but do you remember the guy who posted pics of his tato and the work he did/elongating the one hole to make it bolt in?  I am with you and believe it best testing things stock first, that way you know where you started/how far you have to go, and you can better see the gains/results along the way, knowing you are heading in the right direction (and it's a nice reward too 8) ).  I also agree, no successes without some lengthy (and not worth the effort/not fun enough for some people  :roll: ) hard data, I have posted in the past my findings on back pressure and intercooler temps and pressures dif and got no reply, so I have kept to myself about all this work, but you know info like this will tell you what you are working with and your gains along the way and is the proof you need to know you did good in the end, sometimes use the data to clear out someone claiming BS too  :lol: !

Ohhh, NICE to have machine shop there for you, may not be too hard to find an 18mm X 1.50 tap if you need one, I had to use a machine supply catalog to order one.  So no problems for you grafting up what you need with your shop there, just a heads-up, here are the pics of the 2 styles of plugs I know of, the small one is from ATP and does not allow as much meat to play with when drilling and tapping or whatever you use to get you setup.  The bottom one is nice for just such work and is from Motec though I think others are starting to stock these, I just liked getting it from Motec as when I got their catalog, I was like a kid in a turbo shop, ya know, I need 2 of the big ones and Harry, I need it by tonight 8) .

The O2 plugs I've seen were in summit or jegs and they looked like the ones in the 2nd picture you posted.  I actually have to check tomorrow if we have a die that big as I'm not sure if we do or not.  I remember seeing a couple of big metric dies laying around, but I don't remember what sizes they were.  I'll just order the O2 plugs if I can't find one as a die could over $40 for one that big(I know the taps are around $45).  Anyways,  I actually just ordered from summit so I have to ask my friends if they want anything as I don't like ording a lot as you have to pay $8.95 or so for 'handling' for every order.  I actually did want to order some reflextive sleeving to put over the fuel lines as they make me nervous with them being where they are over the turbo/downpipe.  I just replaced the o-rings while I had them apart as they where practically non-existent.  I'm wondering if the lines are the same as regular GPs??  I've heard them referred to as 'ABS fuel lines', and I'm thinking that all 89-91 or so ABS w-bodies(powermasterIII anyways) had the same fuel lines.  I just looked at a '91 supreme at the yard that had a powermasterIII and I forgot to look at the lines. :roll:  Anyways, thanks for the tips and I'll post my results when I'm done. 8)

Quote from: god910What are our options when we are talking about air temps?  I will update more later, but I am building a computer for the car.  So, I will be able to do a whole lot w/ it.  I would love to stick different temp sensors in the intake/exhaust tract to monitor and gain from those readings.  I am thinking:
1) before turbo
2) after turbo/ before I/C
3) after I/C
4) Just before T/B (or will the sensor in the upper plenum be close enough to upper I/C that it will be the same?)
Also, being as the I/C and T/B are so damn close I could get rid of #3 and just put it right before the T/B to get a better idea of how cool it STAYS after the I/C.

Then on the exhaust side, all you really need is manifold exit temps and post turbo temps correct?  Will you even be able to get exact manifold temps due to the log manifold?  I doubt it, being as it's not a diesel, and we can't really tune fuel per cylinder are exh. temps even an issue?  So, Jeff, what are you using to measure air temps?

You forgot too :lol:   About me posting all this info before, see if you can search before I do so I can pull it back up, I think I posted it on the other TGP site too but its asleep right now :cry: .  There is some laptop software for running sensors and recording the data, been around for a long time but nothing as slick as some of the data logging sensor systems out today that incorporate your engine vitals such as rpm and load, more bucks for sure.  Motec has a nice array of sensors for just such a project, their loggers tooo much cash for us DIYrs :shock: .  On the temp sensors, I would stick with just air readings, after the turbo, after the intercooler, in the intake and the one in there now gets some pre-heating/conductive from the metal of the upper intake, but it can be isolated.  AND one in the head's intake port so someone can verify the actual runner temps as the air enters into the combustion chamber, though there are many compensation tables for pulling together the MAT with ECT, these need some tweaking!  I would pass on exhaust temps, too limiting in the value of this reading, and too confusing for many to know what it means as on it's own it can mislead you badly!!  You can use your Wide-Band to get proper readings on your combustion so no worries on the exhaust temps, other than them being hot from too much backpressure, but a pressure/boost gauge will tell you more about your BP 8).  As for my temps, I have some fast acting K-Type (I think K-Type) thermocouples plugged into a Hand-Held digital meter with dual temp reading, differential temp reading/Delta T and data logging capabilities, just wish I had one this slick for pressure readings but for now just use my digital camera in movie mode and play it back later showing the pressure readings and the rpm gauge of my gauge cluster in the background at the same time to match things up closely 8) .

Jeff M

Quote from: skalorThe O2 plugs I've seen were in summit or jegs and they looked like the ones in the 2nd picture you posted.  I actually have to check tomorrow if we have a die that big as I'm not sure if we do or not.  I remember seeing a couple of big metric dies laying around, but I don't remember what sizes they were.  I'll just order the O2 plugs if I can't find one as a die could over $40 for one that big(I know the taps are around $45).

That was the other place :cry:  I guess it was too obvious and I was thinking too hard to remember.  I like the big ones too since they are high-temp stainless, and come with that soft/malleable copper sealing washer 8)  Yea my 18 mm die was a few bucks, fun making sure you are perfectly square with the surface you are threading with this honker!!

Quote from: skalorAnyways,  I actually just ordered from summit so I have to ask my friends if they want anything as I don't like ording a lot as you have to pay $8.95 or so for 'handling' for every order.  I actually did want to order some reflextive sleeving to put over the fuel lines as they make me nervous with them being where they are over the turbo/downpipe.

I just placed a few orders with Summit (I won't say how much $$  :oops: ) and like you idea, order everything at once as their free shipping sucks when they keep adding in that Handing Charge!  There is some better stuff, from like Taylor that is FireSleeve, soft silicone outer, thick inner ceramic woven fiber liner like insulated underwear, easy to install, keep clean, looks good and works better than most insulations.

Quote from: skalorI just replaced the o-rings while I had them apart as they where practically non-existent.  I'm wondering if the lines are the same as regular GPs??  I've heard them referred to as 'ABS fuel lines', and I'm thinking that all 89-91 or so ABS w-bodies(powermasterIII anyways) had the same fuel lines.  I just looked at a '91 supreme at the yard that had a powermasterIII and I forgot to look at the lines. :roll:  Anyways, thanks for the tips and I'll post my results when I'm done. 8)

Last I heard from some good info guys was normal 3.1L W-Bodies had really long fuel lines that were a mess to use in place of ours, BUT not sure if they looked into an ABS setup, good idea 8)  :D   I have a spare used set of these at the local maching shop having them looking into a source to make these up or fix them better than the attemps I have seen done a few times by others (sorry to those "others" just trying to find a cleaner setup 8) ).

Good luck!!

Jeff M

I'd like to offer some clarification between the "Disco Potato" turbo mentioned.  As far as I know (and I'd really like to hear otherwise!), only one person is running a Garrett ball bearing turbo on their TGP and it is not a Disco Potato.  The person in question is "Jud" or "SleeperRed90TGP".  He posted the photos on his website of the install (fantastic stuff Jud!!).  He has a GT28R which is the older style.  According to ATP it's rated at 290HP.  It also has the less desirable bolt-flanged compressor inlet and outlet which is a dead giveaway to the fact that it's a GT28R.  

Here are some references on the web showing the GT28R with its easily identifable flanged inlet/outlet.: http://www.turbobygarrett.com/turbobygarrett/kits/kit_HondaCivic.htm#
http://www.atpturbo.com/root/turbopiping/dimensions/gt28rdim.htm

The Disco Potato is actually the GT28RS which no TGP owner has mentioned actually owning yet.  According to ATP Turbo, "The GT28RS is a new and hot one that would kick butt on this engine.  How would you like it if it spools up faster than the Super60 and make 50 wheel more than it.  It's a much new Garrett turbo than Gt28R so it's quite modern."  Interestingly enough, Garrett itself refers to the turbo as the "Disco Potato".  Take a look at this great high resolution image: http://www.semaphotos.com/photos/C_00375.JPG
Here's another photo from Exile Racing:

So whoever is the first to try the GT28RS will likely have an easier time adapting the intake inlet/outlet than Jud did and may possibly produce more HP as well, seeing how the GT28RS is rated at 350HP by ATP.

Quote from: TookyCatI'd like to offer some clarification between the "Disco Potato" turbo mentioned.  As far as I know (and I'd really like to hear otherwise!), only one person is running a Garrett ball bearing turbo on their TGP and it is not a Disco Potato.  The person in question is "Jud" or "SleeperRed90TGP".  He posted the photos on his website of the install (fantastic stuff Jud!!).  He has a GT28R which is the older style.  According to ATP it's rated at 290HP.  It also has the less desirable bolt-flanged compressor inlet and outlet which is a dead giveaway to the fact that it's a GT28R.  

Here are some references on the web showing the GT28R with its easily identifable flanged inlet/outlet.: http://www.turbobygarrett.com/turbobygarrett/kits/kit_HondaCivic.htm#
http://www.atpturbo.com/root/turbopiping/dimensions/gt28rdim.htm

The Disco Potato is actually the GT28RS which no TGP owner has mentioned actually owning yet.  According to ATP Turbo, "The GT28RS is a new and hot one that would kick butt on this engine.  How would you like it if it spools up faster than the Super60 and make 50 wheel more than it.  It's a much new Garrett turbo than Gt28R so it's quite modern."  Interestingly enough, Garrett itself refers to the turbo as the "Disco Potato".  Take a look at this great high resolution image: http://www.semaphotos.com/photos/C_00375.JPG
Here's another photo from Exile Racing:

So whoever is the first to try the GT28RS will likely have an easier time adapting the intake inlet/outlet than Jud did and may possibly produce more HP as well, seeing how the GT28RS is rated at 350HP by ATP.

This talk is all well and good 8)  but we need proof that can only come from testing, I don't mean slap it on and run a time slip, but find what it takes to get it all to fit and work, and prove we have lowered our backpressure problems with any of these turbos or others and which one was best and for the bucks, and the all important; a chip/injector-fueling tuned to work properly with it all!  We also have to consider any other challenges that might come like too much pressure drop with the stock intercooler (I myself have already done pressure and temp readings of the intercooler with stock and a T28, and there will be some issues there with more air flow!).  Are you going to step up to taking on some of these challanges to help out :) ?

Jeff M

Quote from: Jeff MAre you going to step up to taking on some of these challanges to help out :) ?

ABSOLUTELY!!!  But only if I can find a stout automatic transmission for a reasonable price (not $3000).  Otherwise, my turbo would already have been ordered.  Unfortunately my transmission search still continues.  The best I found so far was Level 10 which seems unproven, untestified, they don't list the changes/upgrades/components, and it costs $2500 + torque converter + I have to give up my core.

Quote from: Jeff Mand the all important; a chip/injector-fueling tuned to work properly with it all!

Do you, or does anyone else, offer such a chip?

Quote from: TookyCat

Quote from: Jeff MAre you going to step up to taking on some of these challanges to help out :) ?

ABSOLUTELY!!!  But only if I can find a stout automatic transmission for a reasonable price (not $3000).  Otherwise, my turbo would already have been ordered.  Unfortunately my transmission search still continues.  The best I found so far was Level 10 which seems unproven, untestified, they don't list the changes/upgrades/components, and it costs $2500 + torque converter + I have to give up my core.

"ABSOLUTELY" Sounds good, sure you are not going to throw in the towel when you find more hitches or glitches, or broke parts? :lol:   I heard you swearing and threatening to get a GTP when your tranny went :cry: (sorry to hear that).  It costs to R&D things out, you don't always get lucky and find the perfect piece right away, who is to say the stock head bolts will hold with more mass air in the engine :shock:   There are many things to look out for and be prepared to address, that might include being the one to test the Level 10 Tranny. :P

Quote from: TookyCat

Quote from: Jeff Mand the all important; a chip/injector-fueling tuned to work properly with it all!

Do you, or does anyone else, offer such a chip?

At the time you were thinking about having this bigger turbo above, but broke the tranny, did you already have a chip ready for it then?  Can't have one without the other :?

Jeff M

Actually I never considered getting a GTP, the only one to suggest that was you when you said if I wanted these types of HP levels, I should look at getting a GTP??   ( http://www.netavalanche.com/tgp/viewtopic.php?p=10882#10882 )

Quote from: JeffM

Quote from: TookyCat

Quote from: Jeff Mand the all important; a chip/injector-fueling tuned to work properly with it all!

Do you, or does anyone else, offer such a chip?

At the time you were thinking about having this bigger turbo above, but broke the tranny, did you already have a chip ready for it then?  Can't have one without the other :?

I already addressed fueling in my High Performance post seen here
But nonetheless, I am still wondering if you or anyone else offers such a chip as you're referring to?  Thanks,