Too much turbo lag!

[Na06ce]

it comes on at 2000 rpm now I thought was implied, as opposed to 4500. Obviously didn't explain it well enough.

[NitroDann]

the t piece holds the wastewater closed until target boost is achieved, helping spool but even with this exact mod pat brimstone na6 with identical kit, and on E85 still doesn't spool till 4000rpm. There is nothing wrong with the manifold design, except that sits the turbocharger too far back and at the same height as the chassis rail shelf which doesn't allow room for a big enough dump pipe.

As well as changing the design of the manifold to allow better turbo placement I'm also improving design for much more flow and adding a 3'' exhaust.

Dann

[sticky nicky]

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Ok, Ive had a look and taken some photos for you. My engine is currently in bits and being rebuilt. I think I see what you mean now by the change of shape in the pipe because of the firewall, what a stupid design. It looks quite restrictive. Can this section be replaced by just buying a piece to bolt straight in?

Also the exhaust from that piece to the muffler measures 8' around, so 2.5' across? Then I have the muffler which an invoice I dug out from the previous owner says its a "Lukey Turbo Muffler", but cant find any writing on it. Then from the muffler back the pipe measures 6.5" around, so 2' across?

Hope this is enough info, yes all Im interested in is the turbo kicking in earlier, not more power. I dont know if I can do any changes fairly cheaply as the engine rebuild is crippling me at the moment

Cheers

[Sean]

Dan is right on this one.
I've had experience with exactly this issue on two turbo NA6s including my own.

The AVO dump pipe is the biggest restriction IMHO. It looks like a doorstop, particularly the first gen AVO kits.

Replace it with a tubular nice round free flowing dump and you'll both spool up to boost quicker and make more power without the need for a boost controller.

[Na06ce]

I also agree with what he is saying, but not at 7 psi boost, I as you know Sean have run 23 psi through the avo set up, the restriction only becomes evident above 15psi and am also under the opinion bramstons car is making over 200 kw at the wheels with the horrible dump pipe.
Of course less restriction is going to be better but does he need this now ?
Steve.

[sticky nicky]

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Yes, Im happy with my power at the moment and not interested in turning the boost up, but need the turbo to kick in around 2000rpm instead of 4500rpm.
The whole avo set up does look very restrictive. But if I replace the downpipe with something round, the other bit that bolts to the manifold.....shown in the above photos still looks really restrictive so would this need to be replaced as well or is it part of the turbo? This bit also has something attached to the top of it.
I dont know if something like this is what I need?

http://www.ebay.com.au/itm/130484865805 ... 1423.l2649

Arrrrgh...........I wish I knew more about mechanics!

Nicky.

[NitroDann]

I also agree with what he is saying, but not at 7 psi boost, I as you know Sean have run 23 psi through the avo set up, the restriction only becomes evident above 15psi and am also under the opinion bramstons car is making over 200 kw at the wheels with the horrible dump pipe.
Of course less restriction is going to be better but does he need this now ?
Steve.

Sorry about my last post, was on a new phone.

Pats car max's the AVO turbo/mani/dump out at 18psi. Because he has a nicely modified head, it restricts less and boost pressure is lower for a higher HP figure.

The dump pipe isnt just about horsepower. Its about backpressure.

With a good manifold and a huge dump pipe, lets say 4" straight out the back, the difference in pressure inside the manifold, compared to the pressure in the dump pipe is huge, it might be 30psi in the manifold and 0psi in the dump. That rubbish dump pipe means that it may be 30psi in the manifold and 15psi in the dump.

This means the effective pressure is only 15psi (30 minus 15) not 30psi (30 minus 0).

Therefore it has half the force to turn the turbine wheel, which in turns means it spools up to speed half as fast, and spools twice as late.

Dann

[Sean]

I also agree with what he is saying, but not at 7 psi boost, I as you know Sean have run 23 psi through the avo set up, the restriction only becomes evident above 15psi and am also under the opinion bramstons car is making over 200 kw at the wheels with the horrible dump pipe.
Of course less restriction is going to be better but does he need this now ?
Steve.

Power wise I agree the restriction comes in with a typically sized (or stock avo) turbo around 15psi. But delivery wise, I picked up power/boost sooner once we had the custom dump on there.

[sticky nicky]

Or should I go for something like this?

http://www.ebay.com.au/itm/400014905640 ... 1423.l2649

Otherwise can you guys send me any links with something that will fix the problem?

Thanks Nicky

[Sean]

Or should I go for something like this?

http://www.ebay.com.au/itm/400014905640 ... 1423.l2649

Otherwise can you guys send me any links with something that will fix the problem?

Thanks Nicky

I would'nt buy that manifold.

I'd get a custom dump made to mate up with your existing set-up.

[NitroDann]

That ebay manifold will die in a fortnight of use, they are paper thin.

Dann

[sticky nicky]

Ok, excuse my lack of knowledge......... but do I just need to get the dump pipe custom made and keep the Avo manifold?

As in my above pics, do I need to change the thing between the avo manifold and the avo dump pipe as it looks very restrictive (see photos) It also has something connected to the top of it. If I just change the dump pipe and not this other piece will the turbo kick in sooner?

Cheers

[NitroDann]

I think you are talking about the exhaust housing, this is part of the turbo.

You need to change the dump pipe only, but its very hard to fit a much better one in there with that manifold, btu if you change the manifold to relocate the turbo you will need to modify the intercooler and intake piping and it all gets complicated.

One option is to buy a whole new custom made setup and sell what you have, which is still valuable because they are proven super reliable.

Dann

[sticky nicky]

Ok thanks, appreciate your help and advice

[rxmx]

I had an na8 powered by avo kit and the dreaded dump pipe. Running 1 bar boost (14-15psi) and it definitely wasn't a lag monster, contrary it was prob one of the more responsive setups I've owned for the power level ~ 170rwkw with small frame turbo .64 rear housing. I would be looking at other factors first. Try pulling your cat out and inspect, you may have other restrictions in your exhaust that can cause unwanted back-pressure, just a thought