Ford Mustang Forums banner

1 - 20 of 54 Posts

·
Registered
Joined
·
257 Posts
Discussion Starter #1
I have an on3 kit with a T78. Just had the car tuned/dyno'd and its boosting super weird, almost like really bad lag, but there is no way that turbo is laggin that bad.....

The motor is good to handle what its making easy and ive got a build 4r75w with PI converter and Freddy Brown FMVB.

Pretty much its boosting like a centri blower, Im thinking its a wastegate issue.... Just wanted to get some more input before i go splurge and spend $500 on new wastegates......




Any ideas would be much appreciated....

Pretty much down to a vacuum problem (really doubt it) or wastegate...... But even then the way its building boost seems odd to me.

Thanks,
Ethan
 

·
Registered
Joined
·
873 Posts
t78 = big


most 76mm cars dont start building boost till 4k(im speaking 4v, not 2 v)

so if this is on a 2v car, without knowing what freaking motor your talking about , which kit , gear, etc etc(you left out a ton of details here) id say the turbo is too big for your combo
 

·
Registered
Joined
·
257 Posts
Discussion Starter #3 (Edited)
Built 4v. 8:5.1 compression with 98 cobra cams and 3.55s.....
Running e85

It may be my turbo is too large, just wanted some input.
 

·
Registered
Joined
·
1,647 Posts
What intake manifold? C-Heads? Cams degreed?

It is tough to say.....but I don't think it is a WG issue. That is some low compression, with a decent size turbo.
 

·
Registered
Joined
·
1,361 Posts
Are you running off the wastegate springs?

Get a electronic boost controller like the eboost...it makes a huge difference in how the boost comes on.

The wastegate starts opening slowly without a controller which is why your power is coming on like a centri, with a boost controller you can set the boost to say 20 psi and tell it to keep the wastegate completely shut until 18 psi.

Your waste gate is fine.
 

·
Registered
Joined
·
257 Posts
Discussion Starter #6
What intake manifold? C-Heads? Cams degreed?

It is tough to say.....but I don't think it is a WG issue. That is some low compression, with a decent size turbo.
Mach 1 intake and heads. I'm still not sure on cam degree, I'm thinking that might be part of the issue as well.

I only have a manual boost controller, I plan on gettin an ams1000 controller when I have a little more money.
 

·
Registered
Joined
·
873 Posts
normal 4v with a big turbo honestly....

only way to get it to spool faster with your combo is running more compression honestly and with e85, a 9.5 to 1 motor would spool it better.

try using a dump pipe off the turbo, it will help spool it about 500 rpm faster or so.

a better sized turbo with different wheels would change all of it honestly tho
your not having a waste gate issue
 

·
Registered
Joined
·
257 Posts
Discussion Starter #9
Already running open downpipe and no intake
 

·
Registered
Joined
·
257 Posts
Discussion Starter #11
Ever think about putting a smaller Turbo on it?


I've got a 67mm with a .96 a.r and I'm not even seeing full boost till 4k or so with a 2v
I might get another turbo, ill see how this one does at the track first. Just wanted to make sure something wasnt wrong with it before i went to the track and beat on it.
 

·
Registered
Joined
·
1,361 Posts
I might get another turbo, ill see how this one does at the track first. Just wanted to make sure something wasnt wrong with it before i went to the track and beat on it.
I mean there is a few things to check.....obviously boost leaks can cause slow spooling.

Check all the vband connections with the car running for leaks, you should be able to feel air around them if they are leaking.

You said on3? what kit... Front facing kit?

I just had mine tuned and it looked somewhat like that on the dyno, 4-5 psi by 4k, and only 9-10 psi by 4500 rpms and I had boost leaks out of all 3 v bands.

Now that I fixed the leaks, boost pretty much all hits at one time around 4k rpms.
Also, I know you said your running a manual controller, not sure how they work but with my eboost controller like I said earlier, you can set the wastegate to stay 100% closed untill say 19 psi and have it set to 20 psi and boost should come up really fast vs when I was running just springs, my boost looked like yours, almost like a centri blower.

Anyways, what size a/r are you running on that turbo?

You could try downsizing the a/r way down to try to spool it faster...maybe a .61 backside.

I know thats a big turbo but I would think it would fully spool at some point, that thing seems like it still hasnt stopped climbing at 6k?

How much boost was it set for?
 

·
Registered
Joined
·
257 Posts
Discussion Starter #13
I mean there is a few things to check.....obviously boost leaks can cause slow spooling.

Check all the vband connections with the car running for leaks, you should be able to feel air around them if they are leaking.

You said on3? what kit... Front facing kit?

I just had mine tuned and it looked somewhat like that on the dyno, 4-5 psi by 4k, and only 9-10 psi by 4500 rpms and I had boost leaks out of all 3 v bands.

Now that I fixed the leaks, boost pretty much all hits at one time around 4k rpms.
Also, I know you said your running a manual controller, not sure how they work but with my eboost controller like I said earlier, you can set the wastegate to stay 100% closed untill say 19 psi and have it set to 20 psi and boost should come up really fast vs when I was running just springs, my boost looked like yours, almost like a centri blower.

Anyways, what size a/r are you running on that turbo?

You could try downsizing the a/r way down to try to spool it faster...maybe a .61 backside.

I thought about downsizing the A/R to see how that worked. Right now its a .96 which is too big, but i thought it would be fine. I might try and pick up a electronic boost controller before i swap turbo's seeing as i want to get one anyway.
 

·
Registered
Joined
·
401 Posts
It's a big turbo thing. Good thing you can leave off a t-brake and don't have to shift. Honestly a wet 100 shoot would be the ticket. A lot of 4 cyl guys have to run nitrous on the little end to build boost with a large turbo.

Sent from my Incredible 2 using Tapatalk 2
 

·
Registered
Joined
·
1,361 Posts
I thought about downsizing the A/R to see how that worked. Right now its a .96 which is too big, but i thought it would be fine. I might try and pick up a electronic boost controller before i swap turbo's seeing as i want to get one anyway.
Yea, I mean for that turbo that seems pretty damn big, even with a 67mm and a .96 a/r I feel like im not seeing full boost till 4k or so, and thats only 10 psi.

I would suggest getting an electronic boost controller, check for leaks, and if all else fails you could throw a small a/r on it...but thats only gonna help so much.
 

·
Registered
Joined
·
257 Posts
Discussion Starter #16
I just talked to the place i got my turbo from. They said with that turbo and my setup if i dont see full boost by 4000 rpm then something is wrong..... Whether it be an exhaust leak or bad wastegates.... Also gonna try and run my vacuum lines to the wastegates a little differently, gonna use both ports instead of the bottom. Gonna run them as if im using an electric boost controller.
 

·
Registered
Joined
·
1,361 Posts
Lol that place sounds like they don't know what they are talking about
..and o don't think it's OK to do that with the waste gate plumbing.

My electronic wastegate only uses the bottom port.

I would expect you to see full boost by 4500-5k rpms though which I think should happen if you have no leaks and a good boost controller that keeps the gate 100% closed until you see that boost.

Just seems like boost never really shoots up like it should...once you get that thing spinning I would think it would go from 5 psi to 20 psi very quickly.
 

·
Registered
Joined
·
1,361 Posts
Im just saying, my 2v auto setup isnt seeing 10 psi till somewhere around 4k rpms with a 67mm turbo and a .96 a/r so keep that in mind.

Your running a 78mm turbo with the same a/r and it looks like you saw 10 psi around 4500 rpms so it really doesnt seem that off to me.
 

·
Registered
Joined
·
257 Posts
Discussion Starter #19
Lol that place sounds like they don't know what they are talking about
..and o don't think it's OK to do that with the waste gate plumbing.

My electronic wastegate only uses the bottom port.

I would expect you to see full boost by 4500-5k rpms though which I think should happen if you have no leaks and a good boost controller that keeps the gate 100% closed until you see that boost.

Just seems like boost never really shoots up like it should...once you get that thing spinning I would think it would go from 5 psi to 20 psi very quickly.
Yea but its hitting 5psi at 4000 rpm but not making full boost until 5800......? The only other thing i can think of other then wastegates and boost leak is my BOV is getting vacuum from the intake manifold while the wastegates are getting it from the turbo... Could that cause it to not get enough pressure and the BOV to creep? I would think it would stop building boost all together, but just an idea???
 

·
Registered
Joined
·
1,361 Posts
Yea but its hitting 5psi at 4000 rpm but not making full boost until 5800......? The only other thing i can think of other then wastegates and boost leak is my BOV is getting vacuum from the intake manifold while the wastegates are getting it from the turbo... Could that cause it to not get enough pressure and the BOV to creep? I would think it would stop building boost all together, but just an idea???
If the BOV was open you would hear it and damn sure wouldnt be pushing 20+ psi lol.

Thats how mine is set up, IM to bov, wastegate from turbo.

Thats what is confusing me man, I figured it would start making boost and be fully spooled by 4500 rpms or so....I really think you should check for exhaust leaks pre turbo, if its not leaking, but a 300 dollars e boost controller.

Set it to open the gates at 20 psi and see what happens.
 
1 - 20 of 54 Posts
Top