Comp 64 under ht4c compound build thread

Jordan Koehn said:
That comp turbo has a .7 and a 65 turbine wheel. I think if I do anything it'll be a second wastegate as I don't want to lose power by pulling fuel. Although it seems like limiting boost with a second gate would lose some power as well. IDK

Sent from my LG pad
Click to expand...

An issue I have run into is too much drive to the secondary.
I have a gate in my up pipes dumping to the primary, and another gate in front of the primary.

I pulled my intake manifold off, and found soot inside...nothing in the charge pipes, so it's being pushed back out past the intake valves. (Slightly too high of drive pressure.)

I still say dumping to the hot pipe is a must, but at some point, the pressure in the pipe is gonna be enough to kill the secondary. (No differential across the secondary turbine.)
 
Jordan Koehn said:
From a standing start it spools about as fast as I put my foot in it. If I lug it down in OD, like, say to 55-60 there's .5-2 delay. It does still have the single 72 tune on it. So maybe the spool will change a little once I add some timing.

But passing someone going 60 mph is vastly different than the 72. And going up on-ramps? With the 72 I had to start getting on it in 3rd to get some boost built up for 4th. Last night, somebody actually was ahead of me on a up sloping ramp and I got around them from about a 55 start once the ramp widened and never a down shift. Forget about that with the 72 without downshifting which I hated doing.
Click to expand...

That's what I am hoping for. I had a 69 on mine and to drive smoke free. I was always down shifting and had to pay attention to where I was and how far in to the rpm I needed to be
 
I think a bigger housing on the secondary is in order. Drive pressure cruising is 3-5 lbs more than boost. It quickly gets out of hand when I give it fuel. Wish I had got the 50 gate instead of the 40...

Sent from my LG pad
 
Does anyone know if a 50 mm jgs gate will bolt up in place of this 40? And does anyone have a bigger turbine housing for this ct4. 64 65? Drive pressure is around 130 psi with 70 psi of boost. Jeez, I wish I would've got a 50 mm gate to start with.

Sent from my LG pad
 
Are you sure the gate is even opening fully when it should. I can't tell from your pictures but if the gate is mounted between the turbo and manifold on a spacer plate make up two flat pieces of steel with a schraider valve and pressurize with air to see at what psi it is opening. I fought problems with my setup and jgs gate, this made everything make sense when I could see it happening. You can also add regulated air to the opening and closing ports at the same time to get those set pretty close. I started with a dual spring setup that came with mine (bought used) and ended up using one of the single lighter springs and regulated boost pressure to keep it closed until needed.
 
If you don't have the spacer plate mount, use a hole saw and cut a disc from steel plate the same thickness as the flange mount to clamp to the bottom of the gate with a schraider valve threaded in the center for air pressure.
 
Update. I had the stiffest spring installed in the gate and so I put in the next size down spring in. I had to loosen up the regulator 3 turns and now my boost is 70 with drive 80+. However, the primary starts to spool around 25 psi now. While that's fine from a rolling start under 40, its no bueno in OD. It seems tho, that if I tighten up the regulator the drive starts to get out of hand even tho the primary spools at a more desirable time. So I'm not sure what to do with it.

Does this make sense to anyone? I understand a little more now about wastegate but it's still over my head.

Sent from my LG pad
 
Which port or ports are you using on the regulator?

How can you have 130psi drive pressure, and 70psi boost at one setting, and 80psi drive pressure, and still the same 70psi boost the next, when you have the gate dumping into the hot pipe?
Where are you getting the air supply for the regulator from? (Final discharge pressure?)
Did you cap any ports on the gate?
If you are using a gate plate, they are very restrictive, and do not allow much flow. (Poor priority because of the 90* bend it has to make to reach the gate.)
 
Last edited:
Loosening the wastegate should theoretically make the primary spool faster and the secondary spool slower. It seems you are saying the opposite is happening. Are you running a boost gauge in your interstage piping? Would be nice to know the PRs for each stage so you can see how your wategate changes affect them.
 
Extended Power said:
Which port or ports are you using on the regulator?

How can you have 130psi drive pressure, and 70psi boost at one setting, and 80psi drive pressure, and still the same 70psi boost the next, when you have the gate dumping into the hot pipe?
Where are you getting the air supply for the regulator from? (Final discharge pressure?)
Did you cap any ports on the gate?
If you are using a gate plate, they are very restrictive, and do not allow much flow. (Poor priority because of the 90* bend it has to make to reach the gate.)
Click to expand...

I meant to say ports on the gate, not the regulator...:hehe:
 
I welded a 2 inch pipe onto the steed for mounting the wastegate. I smoothed out the transition at the manifold but.... overall boost is going through a regulator and into the top wastegate port. The bottom one is open.

When I say I'm tightening the wastegate, I'm turning it towards the + side or clockwise. The opposite for loosening it.

I don't know about the 130 psi drive, 80 boost part either. All I know is that putting in a smaller spring changed it.

Sent from my LG pad
 
The little turbine and housing are killing you. I ran a 64/71/16SS secondary for quite a while with about 8 different primaries(from a 75/83/1.1 S400 to a GT4718) and never needed an external gate.
 
I just hate to redo my piping to put a different secondary on here... If I could make this work somehow, I would.

Sent from my LG pad
 
Ok, it sounds like you have the gate connected right.

Without gauges on everything, I don't know how anyone can tune a set of twins...I gotta see what everything is doing before I make a change, and then change it, and test again, and again....and again..............and again......lol
 
Jordan Koehn said:
I just hate to redo my piping to put a different secondary on here... If I could make this work somehow, I would.

Sent from my LG pad
Click to expand...

Should be as straight forward as cutting the flange off the hotpipe and welding a new one on. I doubt you'd have major issues getting the cold pipe to line up, depending what charger you go to
 
Let me know if you need some welding help.


Sent from my iPhone using Tapatalk
 
Jordan Koehn said:
Update. I had the stiffest spring installed in the gate and so I put in the next size down spring in. I had to loosen up the regulator 3 turns and now my boost is 70 with drive 80+. However, the primary starts to spool around 25 psi now. While that's fine from a rolling start under 40, its no bueno in OD. It seems tho, that if I tighten up the regulator the drive starts to get out of hand even tho the primary spools at a more desirable time. So I'm not sure what to do with it.

Does this make sense to anyone? I understand a little more now about wastegate but it's still over my head.

Sent from my LG pad
Click to expand...

Sounds like you're gating off the secondary sooner and now you have a lull where you're waiting for the primary to light. The reason drive came way down is because you've shifted some of the workload from the smaller secondary turbo to the larger primary.

I agree with RonA; the secondary turbine section seems restrictive.

Call Comp and see what they can do. The answer might be as easy as swapping the turbine housing.
 
Well, I called jgs today. I played around some more with the regulator and apparently I took to much for granted with the settings. I had the regulator set so that it was actually holding the gate closed. ? My drive seems to be in check now but I started blowing boots off as soon as I got that figured out. Of course, thats how my luck goes. And I lost the clamp so no more testing for a bit.

I do have a 1.15 housing ordered out. I'm not sure whether to return it or give it a try. Earlier today before I started blowing off boots, I seen a 1 to 1 ratio of drive and boost with it topping out at 60. When I tightend up the regulator to try for more boost, I blew boots off right and left. I did see 75 boost at 90 psi of drive for an instant, tho.

This comp turbo has a 75 inducer and 65 exducer on the turbine side.

Sent from my LG pad
 
You must log in or register to reply here.
Top