"to wastegate" or "not to wastegate"

[patrick m.]

off and on for several years this was a hot topic.
the non-wastegated turbos give more power, but come in later, some would argue too late. Mine comes in at about 2000 rpm, and not a moment sooner. Great power, from 2000 up. so much so, that i gladly give up the instant boost ability of my old GM4.
Eventhough max boost is about the same for each at 15psi.
This bigger non-wastegated unit makes more power at any given boost level than the GM4.

But is this true with the popular GM-8?

Can the GM-8 be adjusted to overcome the exhaust flow losses inherent with small "quick spool" turbine housings?

Well.....i cant stand it, i have run the "non" unit now for about a year, its time to play some more.

i'm going to get a GM-8 and try it. I will be looking for changes in overall power.
Im sure it will produce improved bottom-end power.
the test will be can it flow enough to produce similar "highway" power.

[JoeyD]

I would like to hear what difference the GM 8 makes as compared to what your running now. When you say no boost till 2000rpm what about when your cruising down the road at 1400rpms, is it at not boost there as well? Keep us posted.

[patrick m.]

the turbo i run now has a very large turbine housing. it takes quite a bit of throttle to bring the boost guage up in the lower gears.

cruising at 1400rpms = 0psi on the guage.
cruising at 2300rpms will give about 5psi.
any speed 70mph and above will give very good response.

take off from a red light "on the mat"= watch the black smoke, and wait for 2000rpm, boost comes in smooth and strong.

45-55 mph in converter lock-up= NO BOOST!
you have to press throttle far enough to release lock-up, or touch the brake pedal to release lock-up.

the GM-4 provided instant boost, but very little power after 2000rpm.

and lets face it, we need all of the rpm range of this eng.

we'll see how the GM-8 compares.

[99gmccrew]

PatrickM,
My 99' came stock with the GM-8 and the Turbo response throughout the the powerband is very good in my opinion. However I've never compared it to anything else.

I did have a great experience a couple days ago. Pulled up next to a newer F250 diesel at a stop light, at the bottom of a steep long grade. The light turned green he took off quick, so I gunned it. With my boost controller the boost was at 15psi in no time. I slowly passed him with a grin from ear to ear, once he knew there was no chance he gave up. Another GM victory. It was beautiful. :D
I think you'll like the GM-8.

I don't know if you would need it with JK's chip, but his boost controller works fantastic! You can adjust it to your liking. ;)

[ 01-02-2005, 02:31 PM: Message edited by: 99gmccrew ]

[Kennedy]

Karl (present owner f my 96 GMC) has the GM5, and the Peninsular mid sized Switzer units. The Switzer was lazy around town and he wanted better response so he put the IHI back on. He was imediately reminded that the IHI just dies above 2500RPM on this engine.

So we (actually more he) have been working on a different unit, and aside from a poor choice for wastegate pressures (too low) it sound like he has a good running unit so far.

[dieseldummy]

Get a proporly sized wastegated turbo. I am currently running a WH1C off of a cummins. It will start making boost at 1200 rpms and doesn't choke up at higher rpms like the stock gm unit. I have tried non-wastegated turbos of various varieties and non of them compare in the spoolup or power departments...
Justin

[JoeyD]

Justin, Is the turbo off the Cummins a bolt on or does it need an adapter?

[grape]

there is absolutely no reason to run a turbo charger without a wastegate in this day and time. A wastegated turbo is assumed to have enough flow through the exhaust housing and through the wastegate to make peak power.......yet the gate allows a smaller A/R on the exhaust to speed the turbine up faster.

All production turbos that I know of......from four bangers to cummins, to the 6.5 use the T3 exhaust flange.....so yes it will bolt on the manifold.

[dieseldummy]

Joey, Yes the turbo is of the 5.9 cummins used in dodge pickups. It is T3 based and is a bolt on to a 6.5 manifold. The oil return is also the same, however a little creative bending is required. The oil feed line is a metric size, but I found an adapter that worked. I know that grape is a propontent of using the T4 based garret turbo's, but I have seen no reason to use a T4 turbo on a manifold and crosover system that is restrictive and designed for T3 turbos. Also in reality a T3 sized holset on a cummins is capable of at least 350+ rwhp...

[BigDiesel]

What model years are best for a donor holset turbo?

[dieseldummy]

I would say 94 up to 2002. They used the HX35 which is in essense the same as my WH1C...

[Bill Siver]

What about a hybred? Are the GM units actually T3's? If so, you can probably bolt a T4 cold side. I know this can be done with some T3's, the CHRA and everything can be swapped around if you just change the wheels

[grape]

gm cold side is T4. however it's about the smallest t4 inlet wheel made........check out the map for a standard v-trim inlet wheel, very similar deminsions.

[Brandon]

I run a turbo off of a '93 cummins without a waste gate. I tried one off of a '99 but it was to SLOW to spool up.I get alot more response with the non-waste gate unit. The one off of the '93 was a better fit for the oil return line with no creative bending needed. With this turbo I have yet to see exhaust temps above 1000 degrees and coolant temps above 210.

[RT]

Okay, the Cummins Holset turbo will bolt to the 6.5 and the oil line, return, intake can be made to work but how are you bolting up the exhaust? Thanks, RT

[dieseldummy]

i made a custom downpipe out of pre bent 90's and 45's...

[patrick m.]

o.k., the next turbo experiment is on the way!
should have it middle of next week, shouldnt take very long to get it adapted (the last two did'nt) ;)

a report is soon to follow

[dieseldummy]

Any hint to what is next???

[Brandon]

I made an elbow that has a U-flange on the turbo side. The other end is from the original turbo elbow that I machined out and welded onto the elbow. This way I can still use the same down pipe.

[patrick m.]

Originally posted by dieseldummy:
Any hint to what is next??? It is a Garrett made for Navistar. it has a conventional style of watsegate control. (that will be a challenge.)

it has the large compressor housing (T-4), sporting a dual-stage comp wheel. a T-3 turbine housinge with .81 a/r

we shall see.

[dieseldummy]

Sounds good, let us know how it goes.

[patrick m.]

just bringing this back to the front, should have the new turbo by mid week, wont take long to install.

may take a while to adjust, or obtain equipment to adjust, see it has a pressure operated wastegate. this means i need a wastegae controller (some type of pressure bleed device).

I think i will check with my buddy that has the Buick GN, he has an old "bleed Valve", now that he uses an electronic wastegate control system (digital).

[dieseldummy]

If it's a normal diaphram that extends as manifold pressure increases a turbo master type device can be made to work...

[patrick m.]

ok, the new one is here! I see on e HUGE problem, the exhaust elbow does not extend at the same angle, it will be headed towards the heat shield that covers the inj pipes.

Cast iron piece.....2.88inch outlet too.
still have my GM-4 could cut the outlet off of it, cut the new one, add the desired angle weld on the larger flange.......cast iron?

shape of the new one is nice, very open, no indention like the GM-4.

The compressor wheel is HUGE! About 2.5 inch diameter


There has to be a way.

The wastegate is in the "elbow", just as the GM-8. (the GM-4 is in the turbine housing).
If i had a GM-8 "elbow" in my posession, maybe i could cut the mounting flanges off and swap.(bolt pattern is different.


I wish i could articulate my posts as well as RJ, or GMCTD, but alas, i dont have the skills so i decided to post this one as "quick thoughts".

Any and all suggestions are very welcome ;)

[rjschoolcraft]

Where there's a will, there's a way! :D

[dieseldummy]

Any pics to give us a better idea??

[gmctd]

Pictures would help - your descriptions are ok.

Is that the top rear center-mounted turbo for the 7.3 Power Stroke?

grape has info on plasmarc cutting, conley may have info on ni-cast rod, and welding cast-iron pieces.

[More Power]

FYI - Heath produces a Turbo-Master for the Dodge Cummins turbos as well.

MP

[patrick m.]

just got back home, pics on the way.

[patrick m.]

http://www.imagestation.com/picture/sraid156/p216de694733f043cc05db85b271da37e/f54b4df5.jpg
the factory GM-4 turbo, note the exhaust angle.
(nevermind the spider webs) ;)

[patrick m.]

http://www.imagestation.com/picture/sraid156/pf7ccf287d4e6a670d4ef8484fd5c3533/f54b4df1.jpg new model, note different exhaust angle

[patrick m.]

http://www.imagestation.com/picture/sraid156/p026da91bfb00d09aece0060f4e94700e/f54b4def.jpg
this pic shows the large compressor wheel.

[patrick m.]

http://www.imagestation.com/picture/sraid156/p1d03996fa34cae3dd62e9a6e7818056c/f54b4dee.jpg
the rear of the new Navistar model, note any bolt pattern differences, you guys with GM-8 turbos i am hopeing to hear that the bolt pattern is the same as the GM-8

[patrick m.]

if anyone would like any other pics, just say so and i will take them.
I hae to believe a GM-8 "elbow" will not only fit, but exit at the right angle.

RJ, GMCTD: you guys need to see any more pics any angles i didnt capture maybe you would like to see what is under the hood right now?

say the word ;)

[dieseldummy]

Pat, Not having any direct experience with the GM-8 I can't comment on the bolt pattern similarities, but I was looking a us diesels website and the -8 exhaust elbow does have some striking similarities. My only thought was that even if the bolt pattern is the same the physical dimensions may not be? In my past experiences I have always made some sort of backplate out of mild steel and then welded a 90 elbow to it. I'll look through my pile of turbo's to see if I have anything similar.
Justin
On edit: under hood pics are always :cool:

[gmctd]

Not sure what's up, Patrick, but I've not been able to see your avatar, and these pics come in the same way - small rectangle with red x inside.

Yep - refreshed and checked again, same result.

Everyone else's comes thru ok.

[dieseldummy]

gmctd, I had the same problem, but eventually got them to show by right clicking on them and chosing "show picture" from the menu.
Justin

[gmctd]

Got the last pic - that's sufficient, for therein lies a problem.

The problem.

The wg must remain in it's current position relative to the turbine housing, so adapting a -8 elbow would place the outlet in the same position - if the -8 wg assy were even identical in placement, length and dia.

The elbow will need be cut this side (last picture orientation) of the wg, rotated to a suitable angle relative to the 6.5 downpipe, and welded to fit.

Sorry - had to strike that last bit. redface.gif

Other option is to construct an angled flanged riser between the 6.5 manifold and the P\S turbo, with rectangular tubing and 1/2" steel plate.

Tried that at your suggestion, Justin - still only get the last pic.

[ 01-30-2005, 04:46 PM: Message edited by: gmctd ]

[patrick m.]

it seems i can go to "imagestation" website, look at the pics and come back, then the pics show up as intended. :rolleyes:

i could modify the manifold to bring the turbine inlet up to horizontal which would solve the exit angle problem, but i would still have to cut the 2.75 inch outlet off and install a 3 inch outlet.

i think i will stay with the idea of modifying the outlet housing (or finding one that fits) untill i run out of options.

i know i can weld exhaust pipe to cast iron, so i should be able to cut it off, add a piece to correct the angle and add the 3 inch outlet. Im just not sure how durable this would be.
would "nickel" rod be the best bet?

and if i totally ruin it, i could probably make a whole new outlet from steel. the hardest part would be cutting out the exact shape of the flange into 1/2 inch plate.

[dieseldummy]

I have had good success with brazing exhaust pipe to cast iron, not sure if it's the best way or not...

[dieseldummy]

I have had good luck with brazing cast iron to exhaust tubing, not sure if that's the best or not... I have a little pack of cast iron rod I've been meaning to try.

[john8662]

Here is the pic Patrick posted, otherwise it's a little hard to find and see.

http://www.imagestation.com/picture/sraid156/p1d03996fa34cae3dd62e9a6e7818056c/f54b4dee.jpg

Just copy and paste it into a new browser window, and login to imagestation if prompted.

[gmctd]

Thanks, John.

That turbo looks new, Patrick - what's the availablilty?

It will take to welding much better than 'cured' dirty cast-iron.

That thin-wall cast-iron elbow will be subject to drastic temperature swings - ~300deg at idle to 900-1000deg at full load - within a few seconds, requiring all metallurgy involved to expand\contract at the same rate.

Requires the piece be heated to about 5-600deg, arc welded while maintaining overall temperature stability, then temp slowly reduced to ambient, so the weldment will 'cure' without stress cracking.

May require welding half, re-heating in the oven, welding the remainder.
Then immediately back in the oven, slowly reducing oven temps for stress-relief.

Ni-cast rod comes in several alloys for several types of cast-iron, depending on nickel content.

Waterpumps, exh manifolds, intake manifolds, engine blocks, heads, crankshafts, etc - each requires a specific rod.

Cranks also come in cast-steel alloys, but that is another story.

[patrick m.]

today i started building a new outlet housing from steel. I used a 1/4" plate, cut out the flange and drilled the mounting holes. The i built the 3/4" thick block that will retain the "puck" and swingarm.
Next i bent 2 3inch pipes to match the desired curve, and got one of them cut at an angle so that at the end of the curve i had exactly half of the original circumference.

just picture the flange end of the pipe as an oval measuring 3" by 4.5" and the pipes cut at an angle to create a funnel and at the bottom measuring 3 inches.

like i said i got one side, the other side is being very difficult, so i gave up till the A.M. :rolleyes:

on edit, GMCTD i just remembered your question about it being readily availible. I have seen two on e-bay in the last 2 months, the shop i got this one from says they can get more.
it is re-built, and looks pretty nice. If i ever get the W/G housing together, i plan on testing it good ;)

[ 02-01-2005, 03:46 PM: Message edited by: Patrick m. ]

[patrick m.]

made several calls today, may be able to get a W/G housing from a 6.2 kit. seems there was a few Garrett add on kits out there and one of those may fit this unit.

There is another housing for this unit that has a 3inch outlet, but it is for the Ford as well.

a guy a ATS is going to call me back on Friday.

either way, work shall continue on the homemade piece.

[CareyWeber]

Originally posted by Patrick m.:
it seems i can go to "imagestation" website, look at the pics and come back, then the pics show up as intended. :rolleyes:
Patrick,

You need to link to the album the pics are in like Grape has in his sig for others to get to it.

Carey

[rjschoolcraft]

All of his pictures are coming through fine in my browser...

[patrick m.]

http://www.imagestation.com/picture/sraid156/p8ab56d10673692adcc4a5d9a289e2881/f5407e7e.jpg


here is a pic of where i am now on the W/G housing project (keep the laughter to a minimum please) ;)

i have a 3 inch "v-band" weld on i will add once the center section is completed and the W/G lever and puck are installed

i mounted the Gm-4 in a vise with the exhaust inlet flange perfectly horizontal, and measured the angle at the exhaust outlet flange (15 degrees off horizontal), measured how far below and behind the outlet is from the inlet.

I should be able to weld the v-band adapter (steel) to a short piece of 3 inch pipe, swell it a little, and weld that at the desired 15 degrees.
as long as nothing moves during the final weld-up, it will line up perfectly.
(of course "shadetree assembly" doesnt allways turn out that way does it.

[patrick m.]

http://www.imagestation.com/picture/sraid156/p8ab56d10673692adcc4a5d9a289e2881/f5407e7e.jpg

[gmctd]

Now, that could be hurtful, dudes - seems as though I am FORBIDDEN, with underlines, to enter that site, by one....'Apache'....server.

Totally white full screen page, with BOLD, caps, italics, and underlines for emphasis..........
:confused:

Wassup with that? ;)

[dieseldummy]

me to :confused: ...

[john8662]

Ugh, I can't stand imagestation! Figures though, is a SONY product (thats why It sucks!)

Ditto on the "forbidden" error..

[rjschoolcraft]

That's weird. I can go right to it.

[patrick m.]

if i just "click" the link, i get the "forbidden" message too. but if copy/paste, it works. http://www.imagestation.com/picture/sraid156/p8ab56d10673692adcc4a5d9a289e2881/f5407e7e.jpg.thumb.jpg

lets see if this works any better.

[dieseldummy]

I got the link to come through finally, looks like it will work to me. I have no room to laugh, you would understand if you could see the things I have done...

[patrick m.]

http://www.imagestation.com/picture/sraid157/p0b7a9c9af2b098c3e10058335e7b1437/f539b871.jpg

here is a couple of pics of the W/G housing done. http://www.imagestation.com/picture/sraid157/p1a77db82305becad8ccb279a072a8fa8/f539b86a.jpg

i did not use the weld on v-band ring, in case i decide to make another housing (nicer). so i just made one from exhaust pipe.
i flared a 3 inch pipe, cut it off, flared another, welded the two together and "bingo" 3inch v-band ring.

about to start the install ;)

[patrick m.]

well the "tc4305" may be a bust :confused:
all of that work for VERY similar performance to the "borg Warner/ Switzter" that i had.

the only plus so far is boost comes in a little sooner.

will make some adjustments to the wastegate act in the AM.

it also is not as loud as the other unit. (whistle) :(

if nothing else, im sure i can get different comp wheels and housings for this turbo being a Garrett (eventhough the tag reads "Navistar").

so, third different turbo, all very similar performance despite the fact they all have different A/R ratios from 1.00 to .82

one last thing, the W/G housing fits perfectly, no leaks, no rattles from mis-positioned exhaust, and so far, the wastegate arm works great.
further updates to come

[john8662]

I still had some difficulty seeing the images, that is until I tried exactly what you had proposed, copy and paste. I really don't understand why that made a difference. But this didn't start working UNTIL I logged into imagestation. So, use the link on the bottom of Patrick's signature, and login to imagestation. Then, come back here and copy and past the links, and they will then work. Anyways, I looked though the source and found the images that don't show up in the browser and am going to post the link to them to help others not seeing these. I like turbo adapting!

First Image

http://www.imagestation.com/picture/sraid156/p1d03996fa34cae3dd62e9a6e7818056c/f54b4dee.jpg

Second Image

http://www.imagestation.com/picture/sraid156/p8ab56d10673692adcc4a5d9a289e2881/f5407e7e.jpg

Third Image

http://www.imagestation.com/picture/sraid157/p0b7a9c9af2b098c3e10058335e7b1437/f539b871.jpg

Again, copy and paste the links individually into a new browser window after logging into imagestation.

[dieseldummy]

Sorry to hear that it doesn't work better for you. Have the previous turbo's and this one kept egt's in check? My current turbo keeps my egt's in check and now my performance is limited by fuel...

[patrick m.]

well a little more testing time will tell.
aferall, i've only taken one test drive with it.

[patrick m.]

drove it a little more this afternoon, egt is fine (empty). exhaust is noticeably quieter, less rumble. It is around 60 degrees here today, so i drove with the windows down and thats when i noticed the exhaust tone has changed. I figure it is because of the smaller turbine housing.

It definetly starts to boost earlier in the rpm range, also has more part throttle power, most likely a result of the smaller turbine.

max boost is still the same around 15psi.

I may remove it again and inspect the wastegate puck alignment one more time.

[patrick m.]

after many driving situations under my new turbo's belt, it's official.........a deffinite step up.

It has the same interstate speed power as it did before, which is tremendous acceleration at speeds around 70mph. Mash the pedal to 3/4 throttle, and boost whips up and in a couple of seconds were going faster than anyone should on the interstate.

so that is a relief, i did'nt want to loose that.
what i gained was down low. More power all around.
this thing will fry the tires well into second gear. so a few tweaks here, and there....

I think the next item i will make is going to be an air intake system.
I have plenty of three inch pipe, and a pipe bender, i know i can put a port in it for the CDR tube so all i have to do is get a large cone filter to fit a 3inch pipe ;)

[gmctd]

Well, I got a couple pictures to come thru, this time - good work, Patrick.
Appears to be a workable upgrade to the GM-X series.

Guess now I'll have to mosey on down to Airline Auto Parts for a Dealer pull-off, start checking it out.

Have you considered putting a pressure tap in the exhaust flange, before the turbine housing - get a reading on the exhaust back pressure at various Boost levels, with a 60psig gage.
Be a good guage of the improvement over the GM-X.

TBO already has some readings off GM-8 in '98 truck with all upgrades except the 18:1cr pistons.

[rjschoolcraft]

Patrick,

Do you have access to compressor maps for either of the last two turbos you've played with? If not, can you post the model numbers of each?

Are you still happy with the one you just modified?

[patrick m.]

sorry for the delay.
The last two in use are VERY similar.
The first is a "Banks" which is really a "Borg Warner", or Garrett (depends on who you talk to)
T04B model #3130198 listed as 60A/R comp, and 1.00 A/R turbine
The second replacement was a Switzer (spelling) but the box also said "Borg Warner". no A/R stamps either end. but Wheel pitch and diameter appear identical.
The center sections also are identical.
there is no tag on the second one for model numbers.

[rjschoolcraft]

Borg Warner bought out Schwitzer and KKK turbos not too long ago, fyi.

Thanks for the info.

[Robyn]

What was the standard turbo on the 94 Suburban with the 6.5??

[patrick m.]

Originally posted by Robyn C52:
What was the standard turbo on the 94 Suburban with the 6.5?? all came with IHI (isuzu) turbos. The 94 had the GM-4 model same as my '95.

[patrick m.]

Originally posted by gmctd:
Well, I got a couple pictures to come thru, this time - good work, Patrick.
Appears to be a workable upgrade to the GM-X series.

Guess now I'll have to mosey on down to Airline Auto Parts for a Dealer pull-off, start checking it out.

Have you considered putting a pressure tap in the exhaust flange, before the turbine housing - get a reading on the exhaust back pressure at various Boost levels, with a 60psig gage.
Be a good guage of the improvement over the GM-X.

TBO already has some readings off GM-8 in '98 truck with all upgrades except the 18:1cr pistons. I revisited the last few replies just now and realized i never responded to your question, quite sorry.
What did TBO use to measure the EBP? I remember reading a discussion about this, dont recall the conclusion.

Also, have you visited your local "take-off" store yet? If so would like to hear what you found.

[patrick m.]

just bringing this back up top for GMCTD to see ;)

[gmctd]

Hey, Patrick - missed your reply, been feelin' kinda lowly, since movin' 5yds of gravel with a shovel and 36" hand rake, last week.

Started to head down to AAP today, but did not - gettin' lazy in my old age.

Tim just plumbed a copper line to an 1/8" tap in the exhaust, similar to an EGT tap, hooked it to a 60psi oil\air pressure gage, to compare EBP with Boost levels.

Seems like I read where Bill Heath was running some EBP tests, with intent to post them here.
Tim reported some numbers that Bill considered worrisome, but haven't heard more of it.

So, I thought you might get more of a sense of what you are accomplishing, by monitoring EBP in your experimentations (that was the slow pitch - here's the fast curve) and posting the results here, for other comparison testing.

I'm wanting to do some hands-on with the Ford 6.0 VV turbo, which has some problem with soot jamming the mechanism, but I'm also keeping close watch for a complete 24v Cummins salvage, to get the required brik-a-braks, jew-jaws, jem-jams, all the pertinent trinkets to implement install in my truck.

Thanks for the heads-up, sorry I first missed it.

[dieseldummy]

FYI, the new Duramaxes use the variable vane Garrett turbo as well with seemingly good success.

[gmctd]

Thanks - I'd seen the DMax version, just hoping for better form factor in the Ford, make it easier to adapt..........

[patrick m.]

now i wish i had an EBP guage set-up before i removed the T04B, i believe it would prove to be the least restrictive.

my first thought about the guage set-up you describe is "can it take this sort of heat"?

[gmctd]

The gage is not flow-thru - the only heat would be at the exhaust-end, unless the gage-end leaked, and the odor should easily be detected, right?

And, btw, best wishes in your new venture.........

[patrick m.]

UPDATE.
the wastegate housing i fabbed is going to have to get a "sleeve" for the wastegate arm to pass-thru.
it seems the movement of the arm is "elongating" the hole.

this tells me that the wastegate is opening and closing quite a bit, so a different actuator could increase total boost pressure.

i will check with my favorite machine shop for a good choice of "tubeing material" next week.

the fix should be very easy. grind the weld off the arm, remove puck assy, bore hole in housing, press sleeve into place, find actuator options from ATS.

[gmctd]

That was the GM-8 improvement over the -5 - the wg shaft bushing was lengthened due to early failure of the shorter -5 bushing.

The -8 exhaust elbow housing with imroved wg bushing can be directly installed on the -5 turbo.

[patrick m.]

BTW JD, i also plan on installing the EBP guage that we discussed a while back.

i have a single guage mount for the "A" pilar, and may have room to mount above the other three.

im going to look for an "air psi" (dont want the gauge to read "oil psi"on the face) gauge, and plumb it with a copper oil psi kit.

think that will work?


on edit, sorry to hear about your non-loss :D , i think now that mine is going to go well into the 200K range (at 196k now). it can grenade anytime after 225k and i will feel like it lived long enough ;)

[gmctd]

That will be a good install - this is one gage installation that will absolutely not function with the nylon tubing.

Or, as my dad used to say - it wouldn't last till the water gets hot, boy.......


And, thanks for tne non-commiseration. ;)

[ 04-24-2005, 08:54 AM: Message edited by: gmctd ]

[grape]

in a well designed system you will be lucky to get the exhaust presure down to only double the intake pressure. Usually in it's much higher, and with the t3 exhaust wheels, i'm betting it's way up there.