Tuning Twins

stlcummins said:
I did some reading in diesel tech magazine, they had the gate on the secondary set at 60 psi on a tow twin setup. I had mine set at 25 and it sucked balls, set my gate to stay shut longer and wow what difference! No where near as hot either.
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What was the top turbo manufacture?
 
So let me ask this, should I operate the gate on the secondary from the compressor on the primary?
 
RonA did it with limited results...he switched back
 
stlcummins said:
So let me ask this, should I operate the gate on the secondary from the compressor on the primary?
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I tried it...took way too long. Drive pressure to my secondary was over 100 psi before the gate opened up.
I was getting 30-35 psi out of my primary.
 
stlcummins said:
So let me ask this, should I operate the gate on the secondary from the compressor on the primary?
Click to expand...

Well, I'm sure it depends on the size of your primary charger... My primary is a lot larger than the secondary... ATS's Aurora 5000 primary and HE351 secondary (stock) chargers... ATS setup has the primary opening the WG, and after putting gauges on the chargers I see why.. The HE351 secondary top turbo is working in its designed efficiency range of 30-40lbs. when the primary steps in relieves it of its duty..

The secondary is fully open @ 40lbs which is at it's max efficiency level (hotter gases) it spools the primary charger way faster than before when set to open @ lower settings.. I defiantly noticed much better pull through out the whole power band... When the WG was set to open sooner (24lbs.) I would notice a pause in the boost and power the moment the gate opened.

Total boost jumps right up to 40lbs. which is when the primary charger is opening the WG @ 29-30lbs...

You need to get a cheap PSI gauge from Lowes ($10) put a 1/4" tee on the WG hose run the gauge up to the windshield.. Set your WG to open close to its rated max efficiency, letting your primary charger open the WG... With the gauge on the primary charger and you know what psi you set the WG to open, you can watch your boost gauge and see what the boost levels are when the primary charger opens the gate and takes over for the secondary.

Now you can fine tune the WG to open depending on your chargers efficiency map ratings.. The key is knowing the efficiency of your top charger so as not to over work it..

Sorry for rambling
 
Extended Power said:
I tried it...took way too long. Drive pressure to my secondary was over 100 psi before the gate opened up.
I was getting 30-35 psi out of my primary.
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You can adjust the waste gate to open sooner i.e. at the end of its efficiency rating therefore dumping hotter gases into the primary and spooling it faster... 100 lbs. seems way to high, but not sure the efficiency rating of your charger.

If you had 100 psi on the secondary the gate was not opening soon enough therefore not feeding the primary letting it spool up sooner. Make that primary take over for the secondary which is the purpose of having compounds...

just my $.02
 
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I still don't have guages yet between stages lol i know I know but seems the truck runs best with the waste gate pinched completely off. 57 over 475 with mach 1.5, tst comp, hrvp, timing box, and i can't get egts over 1130. The wierd thing is I still have a steady stream of smoke at full throttle with everything on high yet egts stay down. Am I hurting myself by doing this? Gauges are on the way but like I said I have always been a huge single nitrous guy. First set of twins. I know there is not much tunning I can do without guages but truck runs great

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Rambling is good thing when it has the info I'm looking for.
rlawless said:
Well, I'm sure it depends on the size of your primary charger... My primary is a lot larger than the secondary... ATS's Aurora 5000 primary and HE351 secondary (stock) chargers... ATS setup has the primary opening the WG, and after putting gauges on the chargers I see why.. The HE351 secondary top turbo is working in its designed efficiency range of 30-40lbs. when the primary steps in relieves it of its duty..

The secondary is fully open @ 40lbs which is at it's max efficiency level (hotter gases) it spools the primary charger way faster than before when set to open @ lower settings.. I defiantly noticed much better pull through out the whole power band... When the WG was set to open sooner (24lbs.) I would notice a pause in the boost and power the moment the gate opened.

Total boost jumps right up to 40lbs. which is when the primary charger is opening the WG @ 29-30lbs...

You need to get a cheap PSI gauge from Lowes ($10) put a 1/4" tee on the WG hose run the gauge up to the windshield.. Set your WG to open close to its rated max efficiency, letting your primary charger open the WG... With the gauge on the primary charger and you know what psi you set the WG to open, you can watch your boost gauge and see what the boost levels are when the primary charger opens the gate and takes over for the secondary.

Now you can fine tune the WG to open depending on your chargers efficiency map ratings.. The key is knowing the efficiency of your top charger so as not to over work it..

Sorry for rambling
Click to expand...
 
In my opinion, a 71mm Aurora 5000 primary is not " a lot larger" than a 60mm He351 secondary.

I'm running an HT4B 83mm primary with my He351 60mm secondary. I'm still tuning but last night during a really, really short highway WOT run, 75psi total, 55psi in the cold pipe between the HT4B and He351 inlet.... I'd say the ported factory wastegate is bypassing plenty of exhaust drive pressure..... I'm still tuning-in the gate but the plan is to get total boost in the 85 psi range with 50psi coming from the HT4B and then the He351 stepping it up to 85 psi at the intake manifold. I know it's not a lot of pressure ratio for the secondary He351, but with the dense air charge coming from the HT4B, I don't want to overwork it to where it's prone to failure.
 
What is the ratio a person should use when building twins?

I'm guessing that with the 480 I have, I should only have something like a 60-64mm for a secondary...
 
I don't know why people think they need a huge secondary. A 62 over S510 did 1132 on fuel. Most think you need a huge top charger but infact you dont.

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inline6power said:
I still don't have guages yet between stages lol i know I know but seems the truck runs best with the waste gate pinched completely off. 57 over 475 with mach 1.5, tst comp, hrvp, timing box, and i can't get egts over 1130. The wierd thing is I still have a steady stream of smoke at full throttle with everything on high yet egts stay down. Am I hurting myself by doing this? Gauges are on the way but like I said I have always been a huge single nitrous guy. First set of twins. I know there is not much tunning I can do without guages but truck runs great

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Click to expand...

Anyone have thoughts on this?

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inline6power said:
I don't know why people think they need a huge secondary. A 62 over S510 did 1132 on fuel. Most think you need a huge top charger but infact you dont.

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Click to expand...

Wasn't there two stages of intercooling on that truck?
 
NickTF said:
Wasn't there two stages of intercooling on that truck?
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he still has a valid point. my 800 was far from 1100, but i did it with a 62 and no wastegate. not the prefered set-up, but still. I think a lot of guys are still going about it all wrong.
 
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