so i'm a little stumped. i built a top mount divided manifold for a 2jz-gte a while back. nothing too different or out there, plain and simple.

i used 1.5" sch 10 for the primaries, 4" collector (two for the divided), 1.5" primaries coming off each collector going to a 2" sch 10 pipe before it hits a turbosmart 48mm wastegate.

turbo is a greddy t88 with pretty big backside, 272 cams, stock intake and 4" turbo back exhaust.

so..... manifold likes to creep, a lot. finally got it under control with a 7psi spring, which would creep to 18psi.

so i swap out the wastegate for a 60mm tial. pretty much same thing. 15psi spring creeps to 25psi. 5.5 psi spring creeps to 12psi.

with boost controller, we've made 28psi by 5500, so its not too sluggish.

so bad manifold design? not totally sure.

back pressure compaired to intake pressure as follows

intake @ 25psi = exhaust @ 16psi
intake @ 12psi = exhaust @ 2 psi

exhaust pressure gauge port is after head but before turbo. in collector closest to front of vehicle.

my exhaust pressure gauge setup = -3ss male welded to collector, -3 brake line straight for about 1' coils 4 times in a 2" diameter then another 1' straight section to a -3mail to 1/8npt female and then finally to a regular old mechanical fuel pressure gauge.

now i'm not really new to building, but this is the first time i've had a manifold creep this bad, especailly with a 60mm gate on it.

tune is pretty conservative (a/f = 11's during pulls and timing should be in the 11~12 degree of advance under full boost 25psi)

ian, before you say anything, i just want to see what other think. mechanical or tune?

before i get a bunch of posts about poor wastegate position, remember that this thing has to fit on a car and there isn't that much realistate once you start craming in large turbos, large wastegates and large downpipes.

manifold in question=



any ideas?


Modified by manifoldmiketyson at 3:42 AM 6/12/2008


Modified by manifoldmiketyson at 3:43 AM 6/12/2008


Modified by manifoldmiketyson at 4:20 AM 6/12/2008

 

Don't know the clearance your working with but it looks like you should put the wastegate tubes off the side of the runners. Right where the three of them meet up so that all three have equal flow to wastegate tube instead of just coming off of one runner. Hopefully you know what I mean. Also it looks like the left collector is setup like I explained try doing the tests on that one.


Modified by andy9775 at 7:53 PM 6/11/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andy9775 &raquo;</TD></TR><TR><TD CLASS="quote">Don't know the clearance your working with but it looks like you should put the wastegate tubes off the side of the runners. Right where the three of them meet up so that all three have equal flow to wastegate tube instead of just coming off of one runner. Hopefully you know what I mean.


Modified by andy9775 at 7:52 PM 6/11/2008</TD></TR></TABLE>

the back wastegate portion is like that, the front is a little harder. i probably could, but the angle would probably be way worse. instead of 90, it would be 180.

we are actually building another right now with twin 48's to see how that works.

the back pressure numbers are kinda throwing me off more then anything.

backside wastegate=

 

Mike, what is the ultimate goal as far as boost pressure? Are you trying to hold 14lbs, 20lbs or ... ? Is there any way you can try and fit two gates in there and fit the one wastegate on the side three runners? Nice looking manifold though

 

trying for wastegate spring or close to it.

i would like 15psi on spring.

i can handle a little creep, but not like that. i can fit two gates no problem. i'm just trying to figure out why i'm getting these results.

if this was a race car running big boost, it wouldn't be an issue.

torque curve on this bastard looks like a supercharger.

 

wastgate placement isnt great but i have seen alot worse work.

are you monitoring egt's?

 

we had a supra here with a 55r on it. when it came it had a single wastegate and with a 12psi'ish spring (dont remember exactly) it made 40+psi with no boost controller. added a 2nd 44 gate and it would hold 15-16

didnt monitor back pressure though

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbo-charged &raquo;</TD></TR><TR><TD CLASS="quote">we had a supra here with a 55r on it. when it came it had a single wastegate and with a 12psi'ish spring (dont remember exactly) it made 40+psi with no boost controller. added a 2nd 44 gate and it would hold 15-16

didnt monitor back pressure though</TD></TR></TABLE>

you just made my day.

glad someone has had the same issue (on some level).

i'm not checking egt's and probably won't on this one.

we've got it holding at 12psi on a 5.5psi spring, so even though there is creep, its managable. most likely we'll keep it there and tune it out with a boost controller to get a nice flat curve.

this car will probably run minimum of 20psi. i guess i'm just trying to learn from the experience.

 

you know more than i do and im sure your design is the result of several compromises but it seems like it would sense to have the collector about two inches longer. this would let you take the waste gate gradually off of the collector so that the exhaust gas doesnt have to make any crazy turns to get to the wastegate.

now that scenario exists in a magical world where packaging is not an issue.

i just remember in the book maximum boost the author puts some emphasis on positioning th wastegate in such a way that exhaust flows right in.

i'm sure i'm preaching to the choir though.

 

Mike...if ever in question..remove the gate and attach a pipe and make a pull without the gate. Easiest way to see what is needed. great looking manifold.

 

is the merge pipe before the wg divided? i'm not sure if this would have an impact, probably not.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NLR &raquo;</TD></TR><TR><TD CLASS="quote">Mike...if ever in question..remove the gate and attach a pipe and make a pull without the gate. Easiest way to see what is needed. great looking manifold.</TD></TR></TABLE>

just keep it venting and make a pull see what happens?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.E.G. &raquo;</TD></TR><TR><TD CLASS="quote"> it seems like it would sense to have the collector about two inches longer. this would let you take the waste gate gradually off of the collector so that the exhaust gas doesnt have to make any crazy turns to get to the wastegate.

i'm sure i'm preaching to the choir though.</TD></TR></TABLE>

that sounds like it may work a little better to tell you the truth.

i went with a shorter collector originally because we had them all ready to go from another manifold.

i can take some crap for my design, i just didn't want the conversation to revolve around the wastegate position. your not stepping on my toes.

thanks for all the compliments on the manifold.

anyone have any input on the back pressure?

 

The lower the backpressure the worse your creep problems will be, that's why the need for such big and/or multiple gates on big turbos.

Those backpressure numbers don't seem all that far off for a very big turbine section. The backpressure numbers on my car are very similar at those boost levels.

The more pressure differential across the gate, the more effective it will be. 5psi in the manifold and 0psi at the dumptube isn't much. There's usually more than double that in the manifold which makes the gates more efficient.

Bigger gates, better entry or more gates is the fix.

 

yes. If it still creeps that bad you know it aint the gate and its the piping.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NLR &raquo;</TD></TR><TR><TD CLASS="quote">yes. If it still creeps that bad you know it aint the gate and its the piping.</TD></TR></TABLE>

you think pipe diameter is too big?

i was originally shooting for a low back pressure setup, but i think it was a little too affective.

 

I had a Supra on the dyno yesterday with a FR twin scroll manifold, twin 44's, and a GT45 with a 1.28 housing and it held 7psi to redline on 7psi springs. I was actually pretty surprised, but it shows that it's definitely doable.

 

Mike, can you add another wastegate off of here?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">I had a Supra on the dyno yesterday with a FR twin scroll manifold, twin 44's, and a GT45 with a 1.28 housing and it held 7psi to redline on 7psi springs. I was actually pretty surprised, but it shows that it's definitely doable. </TD></TR></TABLE>

my buddy ian, was on the dyno the other night tuning a supra with a 76mm t6 running twin 60mm gates and had no issue, however they did do some backpressure stuff and came up with:

28psi intake & 15psi exhaust.

seems like this is probably normal with the bigger turbos.

current manifold will be used as is, but the next one has twin 48's centered on each collector.

i'll have some data on the twin setup here in a couple weeks.

thanks for all the help and suggestions.

honda-tech =

 

my co-worker danny is building the twin gate one, heres some pics of it.

were waiting on the front wastegate until we get everything built due to the tight space requirement.

he swithced the #2 and #3 pipe runs to create some space for us to tuck the front wastegate undernieth behind the alternator.

looking pretty good so far.

we are going to weld a couple test ports on the manifold so we can get more data for more spots. pretty fun stuff

 

Looks like Danny is doing some killer work See you guys Monday

 

Any inner pics of the collector ? We had an issue yesterday with creep on a mini ram manifold. gt30R running a 44mm gate, with a 4.3 spring. I know its a different setup, but the collector is about the same size. The issue on our end I believe was runners 2 and 3 would flow right out to the collector into the turbo, even when the wastegate was opening, causing creep.

We built the manifold, and it has a tear drop shape, so I don't think thats the issue.

Just something to think about.

 

sometimes we weld a wedge into the collector to help direct exhaust flow to the wastegate. Has no impact on turbo performance but usually solves a problem with a low backpressure or bad angle on gate pipe.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NLR &raquo;</TD></TR><TR><TD CLASS="quote">sometimes we weld a wedge into the collector to help direct exhaust flow to the wastegate. Has no impact on turbo performance but usually solves a problem with a low backpressure or bad angle on gate pipe.</TD></TR></TABLE>

like a baffle of some sort? you have any pics of that?

 

think of it like a scoop on the hood of a car. Just something to catch some exhaust flow. Most of our usually mount in the turbine housing and if I cant get a good angle on the pipe I usually insert the complete pipe into the hole I put in the turbine housing. Weld the outside and then grind and port match the pipe on the inside of the housing leaving the bottom about 3/8 of an inch protruding in the the housing and the top flush cut and then welded. This is usually enough to divert exhaust flow into the wastegate pipe and has zero effect on spool and hp.

 

you've got 6 cylinders feeding the turbo... and only 1 of them is feeding the wastegate...

thats your problem..