Car will not make boost. Need some help

Sprayer84

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Back from the dead! Just frustrated with comp. I'm sure they are slammed but it's been frustrating to have three people tell me my turbo is "like new, a little tight & needs broken in" then when I tell them it has 9000 miles in it they sound confused, tell me they will look into it and call me back. Then I never hear from then again lol.




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CPRsm

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Cliff notes? Been a while. Fixed the intercooler and it will won't make boost? Is the wastegate stuck cracked open?
 

Sprayer84

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Boosting ok ish, I just didn't want to start a new thread. Back pressure is high, even at 9psi and the turbo is lazy. Not reaching full boost until 4000/4500 rpm. Sent it in to get checked out. Thinking about the new precision cea 6466


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weather man

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Boosting ok ish, I just didn't want to start a new thread. Back pressure is high, even at 9psi and the turbo is lazy. Not reaching full boost until 4000/4500 rpm. Sent it in to get checked out. Thinking about the new precision cea 6466


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I'll post up what happens with my exhaust mod. One eyed willy said he picked up good gains when he upgraded his 2.5" pipe to 3" from the "Y"
 

RED09GT

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I'm far from an expert but here is my take. The powerhouse turbo kit comes with a precision 6776 and a 0.81 exhaust housing. I am at full boost by 3000 rpm so my suggestion is to go with at least a 75mm turbine wheel.
After all the threads with people having trouble making boost with similar sized comp turbos, I would stay away from them too.

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Sprayer84

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I have yet to speak with justin. I feel like he's the one I need to get a hold of. If jeremy trusts him I should as well. Hopefully I can reach him tomorrow.


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JeremyH

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I'm far from an expert but here is my take. The powerhouse turbo kit comes with a precision 6776 and a 0.81 exhaust housing. I am at full boost by 3000 rpm so my suggestion is to go with at least a 75mm turbine wheel.
After all the threads with people having trouble making boost with similar sized comp turbos, I would stay away from them too.

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Mt first turbo was a cast wheel 6776 precision from the powerhouse kit it had a .96ar. It was lazy as fuck I didnt build any boost till past 2k rpms and at the track the car would launch and then bog out of the hole bad. This was with 3" up and down pipes. Swapped in a .81ar tubrine housing and saw 100-150rpms better spool and picked up around 20rwtq but it was still very lazy. A T4 with 75-76mm turbine wheel can and does support 1000-1200rwhp on 4.6-5.0 motors.

I switched to a billet wheel 6765 .81ar. Boost repsonse was instant when I touched the throttle and I made 655rwhp on 16lbs, power and tq held all the way to 7k rpms. There are guys knocking out 650-700rwhp on these motors all day long with a 6765. Very well matched turbo for your avergae setup on the 4.6-5.0. There are kits that have 60-62mm turbine wheels on the 4.6-5.0 motors knocking out 500rwhp+. Turbine wheel is just a part of the equation, hotside design, size and backpressure are in there too. When sizing the turbo you want the smallest trim you can fit for your motor, kit design power goal etc and still be in the efficiencey range of the turbo so you dont hinder spool and performance.

Common denominator has been the Zimmers kit for people with issues due to the poor hotside and intercooler design. You could can help compensate some by going biger in the turbine but to a point it just wont flow more if the piping deosnt support it. Zimmers contacted us about Comp and about offering their hotside. I put their hotside on my car and had backpressure issues even with a larger 68mm turbine which I posted up on the fourm and told them. They basicly blew me off and I sadly watched the whole thing spin out of control and came back from deployment to find they were out of business and alot of guys were screwed over.

Johns intial issue making boost was due to poor intercooler design and a leak in his intercooler iirc. A smaller turbine wheel is not the reason for not spooling up the turbo and making boost. My best guess now based on videos is a bearing, shaft or turbine wheel clearance issue with the turbine housings, without being able to look at. The shaft should spin freely by hand after properly broken in. They now have a machine to break in the bearings for the oil-less setup prior to shipping which is nice.

BTW, guys with Zimmers kits, we are working on modded up pipe to the turbo to fix the flange design. It will be at cost for material, we will post up more about it when it done.


I have yet to speak with justin. I feel like he's the one I need to get a hold of. If jeremy trusts him I should as well. Hopefully I can reach him tomorrow.


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Yes you want to talk to Joe or Justin, not the reception, sales staff lol

John my single kit has not sold yet and I have my custom 7068 Oil-less turbo all broken in sitting here looking sad, pm me!
 
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RED09GT

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JeremyH

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Powerhouse is my favorite engine bay mount deisgn so far. I would have put the turbo up a tad higher other that well designed kit for sure. Normaly taller gears would load better acounting for a well sized pipe and turbine setup. The gears are helping for sure gets you into rpm quicker to get the turbo moving. Puts you at a higher rpm after shifts as well so it would be less noticeable.
 

one eyed willy

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I agree with Jeremy unless they changed something between the time i got mine and you all got yours....

both of you are using the zimmerman hot side and both are having the same issues....i made 670rwhp with mine on my old 3" custom kit that joshk is now making 740rwhp with, turbo spooled fast enough to break the tires lose anytime i gave it gas. now im using a THP turbo kit and the car is un-usable unless im going in a straight line at just 9 PSI before it kicks the tires out. I have had zero issues with spooling this turbo.....replace the hot side , there is a reason why they no longer make the hot side.

just my opinion
 

JeremyH

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This is the biggest issue. Will need a new flange and some pipe to fix. Send me the up pipe and we will take care it for ya.

Image10032012125517.jpg


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weather man

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This is the biggest issue. Will need a new flange and some pipe to fix. Send me the up pipe and we will take care it for ya.

I don't know, I replaced that with a 3" uppipe and still had BP issues. I am putting a new exhaust system on from where the downpipe drops out. We'll see what happens.

Fuck zimmer.
 

JoshK

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I do have one-eyed-willys old kit, which is all 3". I then put a dynomax 3" catback on and I can tell it flows better than the on3 kit i had with 2.5"y and catback. I dont have any data to prove this, but the butt dyno and the way the turbo picks up feels way better. And the on3/S&H kit will out-flow the zimmers kit all day
 

JeremyH

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We've talked before and I'll take one.

PM me.

I don't know, I replaced that with a 3" uppipe and still had BP issues. I am putting a new exhaust system on from where the downpipe drops out. We'll see what happens.

Fuck zimmer.

You are at around 600rwhp iirc Brian. I didn't see the issues till about there around 14-15psi and higher this was on a 68mm turbine and the unaltered zimmers hotside, your new turbine is around 76-77mm iirc. If you are still having issues it may be elsewhere. The downpipe is all 3" which is fine and you removed the next questionable part which is the turbo up pipe where it feeds up and over the k-member.

Your readings were a little high but not too abnormal, just disconnect the y pipe and run the down pipe open on the dyno and measure it. If you still have issues then its not your exhaust down stream. Yours may be on the motor side which could be coldside/intercooler or engine related, ie cam spec or timing issue. In which case changing turbo or going to a larger turbine isn't going to help anymore. I must admit I'm not too crazy with the way the shop put together your new piping with all the cuts and welds but the larger diameter is still accomplished which will help.


I do have one-eyed-willys old kit, which is all 3". I then put a dynomax 3" catback on and I can tell it flows better than the on3 kit i had with 2.5"y and catback. I dont have any data to prove this, but the butt dyno and the way the turbo picks up feels way better. And the on3/S&H kit will out-flow the zimmers kit all day

I saw around 10rwhp gain when I went to the 3" exhaust with magnaflow magnapacks, didn't measure back pressure and didn't have any hp/tq drop off either this was prior to testing the zimmers hotside. I had zero issues with the on3 hotside as well, made 655rwhp no problem on a 65mm turbine.
 
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