more twin turbo questions

[malibu795]

So you think I should forget getting a larger housing for A5K (K31) and just get an external wastegate?? Or do both??

a waste gate make a small houseing function like a larger houseing, effectively
making the operating range wider.

take a turbo ie a 4088 one with a .85 housing and the otther a 1.19 housing.
the .85 will light faster/sooner then stock but rpm pushing say 3500 will push the charge to over speeding conditions.

hte 1.19 will be alot more laggy then stock but probly be able to run fine with out the risk of overspeeding betwwen 4000-4500

now one can take the .85 housing put a wastgate on the turbo set a desired boost level say 45psi adn you can run the turbo with a .85 housing to 4500 with out the risk of overspeeding said turbo.

in other word a waste gate function alot like a relief valve on the exhaust side
make sense?

 

[nwpadmax]

I wonder what the maps looks like for some of the billet wheel HX 60 turbos.

I asked, and they said "NFW!"

Who is making the billet wheels? There can't be more than a few shops doing it. I bet the maps don't exist unless they're working with someone with a test stand (i.e. big company or maybe a university). A lot of what I hear is anecdotal..."we put that wheel on an gained 6 feet" kind of stuff.

 

[6speedduramax]

a waste gate make a small houseing function like a larger houseing, effectively
making the operating range wider.

take a turbo ie a 4088 one with a .85 housing and the otther a 1.19 housing.
the .85 will light faster/sooner then stock but rpm pushing say 3500 will push the charge to over speeding conditions.

hte 1.19 will be alot more laggy then stock but probly be able to run fine with out the risk of overspeeding betwwen 4000-4500

now one can take the .85 housing put a wastgate on the turbo set a desired boost level say 45psi adn you can run the turbo with a .85 housing to 4500 with out the risk of overspeeding said turbo.

in other word a waste gate function alot like a relief valve on the exhaust side
make sense?

I got you now. :thumb:

So what size wastegate do you reccommend and who can I buy it from?

Appreciate all the help guys!!

 

[malibu795]

I got you now. :thumb:

So what size wastegate do you reccommend and who can I buy it from?

Appreciate all the help guys!!

Tial is considered the best in the industry.. they would probly recommned roun 38-41mm gates ....personally i would still email tial and get thier perfesional advise.. this is the guy i talked to [email protected]. mind you tial is $$$ i know there is a couple other but cant remeber

cause of two reasons... one is the w/g is too small you will get boost kreep meaning that your boost will keep increasing even though the waste gate is wide open.. it doesnt by-pass/relieve enough air.

one two big you have the excat oposiste.. w/g open and you fall under the charger

 

[McRat]

My really strange thoughts on gates are:

If you are going to gate twins, you put BOTH the gates on the little charger. One is set for the PR target of the small charger, but dumps into the big charger. The second dumps into the atmosphere which is your "max boost" gate. This way you use all the exhaust to spool the big charger, but when the boost gets too high, it dumps into the atmosphere instead, slowing both chargers down.

 

[juddski88]

so the one set for PR would not be relieving all the extra pressure how?

 

[McRat]

The first gate releases the gases into the feeder pipe for the big charger. This controls overspeeding of the little charger, but still permits full gases to spool the fatty. If you want to control maximum boost due to engine limitations, then releasing the gasses BEFORE the little charger will dump more gases since the backpressure is higher. This should give better control of the boost.

 

[Noreaster]

My really strange thoughts on gates are:

If you are going to gate twins, you put BOTH the gates on the little charger. One is set for the PR target of the small charger, but dumps into the big charger. The second dumps into the atmosphere which is your "max boost" gate. This way you use all the exhaust to spool the big charger, but when the boost gets too high, it dumps into the atmosphere instead, slowing both chargers down.

Are you talking about the 2nd gate before the primary turbo that dumps into the downpipe or like a BOV ?

 

[McRat]

Both gates IMO should be "pre-turbo", which means before the small turbo. A blowoff would work too for the PR gate.

 

[malibu795]

IMO thats more work then needed pat.. why put 2 gates between the engine and primary charge? one controlls the primary charger and the other controll the secondary..
basicly same thing that is being done puting one before the small charger and one between the small adn large charger and you cna either dump it in the down pipe or atmosphere

can one put two gate between primary and engine sure... but that is alot of exctra piping in an already tight area it would be simplier to put the 2nd gate right next to the secondary/fatty charge

 

[McRat]

If you are going to run two gates, the amount of plumbing doesn't change just because of it's location. Ideally the PR gate is built into the housing, and the max boost gate is plumbed into the pedestal.

Over-running the gate is often a problem with diesels since we produce more exh gases at the same HP level than a gasser, and the gates are designed for gas engines. Go ask a wastegate MFR to send you a 1.75" gate that is set to 60PSI and you will see what I mean. So if the gate is perhaps smaller than you want, putting it on the higher pressure side will make it more effective than the lower pressure side.

Remember that you don't necessarily want a wastegate that uses a sealed reference. You want the reference pressure to be the difference between inlet air and compressor air. So the chamber is plumbed to the inlet, and the actuator side is plumbed to the outlet boost. This keeps the charger in it's map and divides the compressor duties between the two better (more efficiency).

 

[Noreaster]

IMO thats more work then needed pat.. why put 2 gates between the engine and primary charge? one controlls the primary charger and the other controll the secondary..
basicly same thing that is being done puting one before the small charger and one between the small adn large charger and you cna either dump it in the down pipe or atmosphere

can one put two gate between secondary and engine sure... but that is alot of extra piping in an already tight area it would be simplier to put the 2nd gate right next to the primary

I agree with ya & fixed the 2nd part

 

[McRat]

I dunno. If you are going to dump some exhaust into the atmosphere that you don't need, you have two choices:

Hottest air, highest drive pressure, smaller gate required. (pre turbos)
Cooler air, lower drive pressure, bigger gate needed. (post primary, pre secondary going by exhaust order)

Truth is, not all twins (or singles) are gated, and work fine in many cases. But if you are going to spend the money to gate them, why not optimize it?

 

[wingnut96]

Why compounded turbo's instead of one per side like APS? Not enough volume and pressure? Maybe to get enough volume from one per side they'd have to be so large that spool time makes them pretty unusable on the street. Thinking about TT on the Goat but maybe the rpm range of gas vs diesel changes the whole concept. Still lots to learn.

 

[McRat]

If you want more than 45PSI of boost, you will find that single or parallel twins can't do a good job of it. By running compound chargers, you can get high boost without over-speeding the chargers.

 

[6speedduramax]

Where can I get long enough oil supply and drain lines?

 

[McRat]

PPE or BD Power (sponsors) can probably hook you up with parts.

 

[wingnut96]

Thanks McRat. Ummm I hesitate to ask this on a diesel forum but are compounds mainly for diesels? Seems like this would solve a lot of issues with a gas motor. I'll do some checking and maybe this is more common on gassers than I realize. You mentioned STS...wonder if they are doing this on their rear mount turbos? Turbo everything...even the blender!!!

 

[03 D-max]

Ummm I hesitate to ask this on a diesel forum but are compounds mainly for diesels? Seems like this would solve a lot of issues with a gas motor. I'll do some checking and maybe this is more common on gassers than I realize. Turbo everything...even the blender!!!

from what i understand they put them more on just diesels because of the rpm range, a gas has alot wider range with a turbo so compounds are not needed but thats just my .02

 

[wingnut96]

Jacob, thanks for the reply. In reading GM Hi-tech Performance I see a lot of Camaro's/TA's running a huge single turbo on LSX blocks. Might be good on the 1/4 but my mind drifted to street usage and running compounded seems like bottom end would jump right in there and by the time it runs beyond it's A/R then the big one would take over. Might not be much room under the hood on our late model stuff but a certain 68 GTO with a blown motor would have plenty of room for an LSX w/compounds. I was dreaming about a Dmax powered Goat so might be for naught. But I do understand lower rpm benefits and thanks for your .02
Ok I'll stop hijacking. Brain just gets kicked into OD. Out