Input On Possible Restrictions

[Hanaldo]

Hey all,

I am currently trying to sort out some issues with my cars power, was just after some input from people in the know about what may be holding me back, as I have had some conflicting advice. I apologize in advance for the length of this post, I just want to explain everything clearly. Little bit of background for those that don't know, these are my current modifications:

Link G4 Plug-In ECU

Greddy Profec B-Spec II EBC

externally gated Hypergear ATR43 G3

Turbosmart Compgate40

1000cc Injector Dynamics injectors

Plazmaman FFP

Plazmaman 72mm throttle body

JJR 3" bellmouth dump/front pipe

VENOM 5" 100 cell cat

3" custom Kermit Engineering exhaust

Walbro GSS-342 in-tank fuel pump

GReddy FMIC

Splitfire coilpacks

HKS fuel rail

Sard FPR

Performance Springs valve springs and retainers

Tomei Type-B Poncams

Headtorque custom bronze valve guides

ARP head studs.

Now with those modifications, here is the result from my last tune:

The blue line is my low boost setting at 16psi, the redline is my high boost setting at 18psi. As you can see from the curves, there is bugger all difference in power between these two settings. It is the same story with any boost higher than 16psi, it makes the same power at 16/18/20/23psi. So on that evidence, it certainly appears as though I have a restriction somewhere. Now my tuners comments when he tuned the car were as such:

- Aside from pipes blowing off, tuning went well but a little slow as all of the fuel map seems to be quite substantially off. Idle settings were a long way off and transient throttle was poor too. Power does not come that easily with current setup. It's hard to pinpoint one problem, but the intake and intercooler pipework would be my first choice.

*** Remove the hot-pipe completely and replace with mandrel bends of same diameter and with as few bends as possible.

*** Make 1 single 3" cold pipe from intercooler to throttle body.

*** Remove intake and replace with 4" all the way to a bigger pod filter.

*** Check cam timing/position.

He also mentioned that he thinks the standard exhaust manifold is definitely a restriction, but he has tuned cars with the stock manifold to over 300rwkw and has had 3 other cars with the same turbo as me but less modifications make around 295rwkw. So he doesn't believe that is my current problem.

That is all well and good, I was going to work through that list and get the car back to him. However, I took the car to my mate and local custom piping guru, Kermit. Kermit has an excellent reputation here for his work, and he has a good understanding of fluid dynamics and how to design pipework to get the best flow. His input on the matter was that yes, my pipework could be a little bit better and it's probably costing me a little bit of power. BUT, he doesn't think it can be made a LOT better, and he certainly can't see it holding me back 50hp. Maybe 15hp at most. He said he is willing to do it for me, but he doesn't want me to spend what may cost over a grand in custom pipework to only make an additional 20-or-so hp.

SO. I just wanted some input. My current pipework is 2.5", and has a number of 90 degree bends. However it doesn't step down in size, it is all 2.5" except where it goes to 3" at the throttle body. Here is my cold side piping:

Does anyone think that it would be worth redoing all my piping? Keeping in mind that the cold pipe can't really follow another path, any custom pipework would require those same bends. Or am I better off looking at the cam timing or elsewhere?

Thanks a lot,

Martin.

[Lithium]

Have you checked thoroughly for boost leaks?

[hypergear]

This is the G3's turbo's power to boost behavior from 15psi to 23psi.

From 23 to 26psi it didn't gain any more power, means its at a point the turbocharger it self or the stock cam shaft has maxed out.

So in a free flow setup the point of when it stops making power should be around 23psi.

Assume the tuning side is perfect

Exhaust manifold do make a huge difference, the manifold VS graphs are in my thread.

The cooler pipe assume in 2.25/2.5 inches, don't generally affect top end power, how ever longer piping gains lag while short pipes makes better response. Cooler wise a good 600x300x75mm cooler will do the job.

I'm abit suspicious with the Inlet manifold setup, as I've had customer loosing 40kws after change over (probably have done some thing wrong), so might want to double check that. Also check the Cam gear and the cam angles, I believe Trev mentioned about the cam dialing issues that he had with the Type B Cams.

[Crans]

Make sure the plenum is sealing to the stock runners correctly, a friend of mine had issues with this area leaking.

Exhaust manifold should support over 400hp.

Is the intercooler in good working order?

Have you dropped the exhaust before the cat?

Have you check the exhaust temp?

Have you checked Cam timing is spot on?

[boostn0199]

Honestly looking at your list of mods i cannot see anything thats is holding you back. Guess as the others said check for leaks tune timing.

[Hanaldo]

I have checked for leaks without much success, but I'll check again. Plenum is definitely sealing. Intercooler has 1psi drop across the core, exhaust has been dropped before the cat with only a 2hp gain. Not sure about exhaust temp, tuner didn't mention anything. Cam timing is my suspicion as I was getting surge coming up the back hill at Barbagallo in 2nd/3rd with about 60% throttle.

[GTScotT]

I think it has got to be your cam timing.

For the mod list I would ideally want a 3" cooler with 2.5" pipes on hot side and full 3" on cold. But the existing pipes shouldnt hold it back what its missing..

Havent you tried dialing these yet?

[Hanaldo]

No, because I lack the tools to do it myself. Have asked my tuner for a rough quote, but I really don't like paying others to work on my car so haven't had it done yet.

[KiwiRS4T]

Cam timing needs to be done on a dyno. You can do it by the charts etc but it is best done by an experienced tuner using trial and error - i.e. making small adjustmnts and measuring the result.

[hy_rpm]

Hey you sure that long 90degree silicone joined in you your cold side piping isn't kinking under boost ?

Get your fabricator to make that one pipe and use to straight joiners shouldnt cost much in just mild steel

Edited February 22, 2013 by hy_rpm

[R31Nismoid]

When the AT is 21 and the IT is 41 - DD applies correction, which increases it artificially - would be closer to 340hp so even worse

+1 for cam timing, usually the prime culprit when there is ~20-30rwkw missing.

Could also simply drop the exhaust from the front pipe and then see what happens.

[t_revz]

No, because I lack the tools to do it myself. Have asked my tuner for a rough quote, but I really don't like paying others to work on my car so haven't had it done yet.

I've gone from 9psi at 3500 to about 16psi after dialling in.not sure about top end as it hasn't been back on the dyno and I don't drive it hard enough to be able to tell but it does sound different. Unfortunately I'm about to dial in again because I found a small flake of thread locker behind the exhaust pulley which I think has put it about 1.5 degree out. Plus I've got a very small amount of oil weeping somewhere in the front.

Once I'm done you can borrow my tools if you like, or bring it down here sometime. But it may just be as easy for them to adjust gears on the dyno? Yours are both adjustable from the front aren't they?

[Hanaldo]

Hey you sure that long 90degree silicone joined in you your cold side piping isn't kinking under boost ?

Get your fabricator to make that one pipe and use to straight joiners shouldnt cost much in just mild steel

Yeh it's not kinking. Don't see why it would kink under boost anyway, maybe under vacuum. It's not doing anything regardless, car was tuned without the front-bar on so it would have been visible.

When the AT is 21 and the IT is 41 - DD applies correction, which increases it artificially - would be closer to 340hp so even worse

+1 for cam timing, usually the prime culprit when there is ~20-30rwkw missing.

Could also simply drop the exhaust from the front pipe and then see what happens.

Except this is why the 358rwhp figure is crossed out on the sheet. Tuner told me to ignore that because of the correction, real figure is around 350.

Have dropped the exhaust, only a 2hp gain.

I've gone from 9psi at 3500 to about 16psi after dialling in.not sure about top end as it hasn't been back on the dyno and I don't drive it hard enough to be able to tell but it does sound different. Unfortunately I'm about to dial in again because I found a small flake of thread locker behind the exhaust pulley which I think has put it about 1.5 degree out. Plus I've got a very small amount of oil weeping somewhere in the front.

Once I'm done you can borrow my tools if you like, or bring it down here sometime. But it may just be as easy for them to adjust gears on the dyno? Yours are both adjustable from the front aren't they?

Yeh, I think I might just get it into Garage 101 and get them to do it. At the moment my cam gears are standard, but I do have a HKS exhaust cam gear sitting here.

[Hanaldo]

Ok, so just to follow up on this, I still haven't discovered what the issue is.

I have:

- Used an air compressor to pressurize the intake and find any leaks. Found a few, fixed them, no change to problem.

- Dialled in camshafts using the 0.050" valve lift method. Exhaust was 116.5 degrees, changed that to be spot on 115. Intake was 121.5 degrees, which should increase top end power if anything. Neither of these were out by enough to have caused my problem.

- Checked valve clearance, all are close to Tomei's specified 0.45mm, loosest was 0.50mm and tightest was 0.40mm.

- Inspected cat, all good there.

- Made sure turbo bearings are fine.

- Tested pressure drop across intercooler using a manometer, but only dropping ~1psi.

- Compression tested the motor, came back with 145, 150, 150, 155, 150, 145. Wet test didn't make too much difference.

Any other suggestions on what I could check?

[Guilt-Toy]

cam timing once robbed me 100hp on my rb30det about 5 years ago....

+1 on cam timing!

[Hanaldo]

Except it's not cam timing... My tuner thought it was too, in fact he almost guaranteed it was, until he sat on the phone with me well after hours going through the process and he couldn't fault the maths. I can't remember the exact numbers off the top of my head, but I measured the camshaft duration @ 50 thou valve lift on opening and closing to find the lobe centreline. True TDC was correct.

Intake cam was 121.5 degrees. Due to the effort and inaccuracy of adjusting the stock VCT gear, I left that one where it was as it's not far enough out to be a big problem, and if anything it should increase top end where it is. The exhaust cam was 116.5 degrees, I adjusted it to 115 degrees. All as per Tomei specs.

[CEF33Y]

Your investigations seem thorough!

How does it feel 'seat of the pants'?

Been in any other cars with similar mods and power?

Have you had it down the 1/4 to check mph? that usually gives a good comparision to dyno figures.

[Hanaldo]

Feels ok, rather laggy. Pulls ok, but none of the wheelspin that I hear other Hypergear users talking about. I'm not sure if that's due to me having good tyres and the car generally being setup for grip, or just a lack of power, but I suspect a combination of the both. Otherwise drives fine, doesn't hesitate, no surging, no misfiring, nothing. Runs a little bit rough on cold starts.

Drag times are abysmal. Best mph I could manage was 108mph. So confirms that it's definitely down on power and far too laggy.

[GTSBoy]

I know we've been through much of this before, asked questions gotten answers, gotten confused....but I forget the details. So I'll pretend we haven't.

I reckon you're going to have to get a piece of exhaust pipe made up to bolt to the dump, replacing the whole cat and exhaust. Point it out the side as a sidepipe and take the car for a run, even if only on the dyno. If you can't find the restriction in the cooler piping, and the cam timing is correct, then the exhaust is getting close to the last place to look.

Desperation would lead you to put a pressure tapping into the collector of the exhaust manifold and one on the dump, and look at those pressures under full load on the dyno. A high manifold pressure, or a high dump pressure would show you were the problem is (or isn't!).

You might even have to start being paranoid about the fitment of your plenum and lower runners. What if there is a bad gasket match or similar down at the ports? Any chance of a large f**kup down there? Same with exhaust manifold gasket.

[Guilt-Toy]

i would look at removing the cams and putting the stock ones back in and testing it.

the symptoms have cam timing written all over it. more boost no more power. that is exactly what happens.

dont bother dropping the exhaust, just drill a hole and screw in a fitting, then connect it to the dynos boost pressure sensor and measure the pressure in the exhaust, it should not really exceed 7 or 8psi pressure in the exhaust.