Tuning Twins

I will once I get it all back together, I recently just switched to a Phatshaft 62/80. It required a 1/2" spacer to be installed between it an my manifold as where before my Hx40 sat on the manifold. I received the devided spacer and it's for a stainless housing and won't seal up. So, I should have some number up at the end of the week.
 
Just some starters for me, I live at roughly 600' above Sea Level.

I turned My max EGT's got to 1500* yesterday. Once I saw that I let out and didn't even look at my boost numbers. I will say, that I don't have a drive pressure gauge either.
 
Ok, I took the truck out today and saw 66psi total boost and 27psi primary boost. That was with my TST on level #5.
 
Headcase98002 said:
Ok, I took the truck out today and saw 66psi total boost and 27psi primary boost. That was with my TST on level #5.
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I would think your ratios would be better if the primary was worked a bit harder, I would say upper 30's to lower 40's.. Your total boost may go down a bit, but higher boost does not always mean more HP.. I would install a temporary DP gauge for tuning, without a DP gauge your not seeing the whole picture..
 
When a fella conducts these test runs, what is better, doing a roll on like I did, or let the transmission get into OD, and then roll into it?
...I just don't wanna be going 130mph down a back road, and have a skunk walk out in front of the truck...

Just wondering what the best way was to actually "Load" the engine, and get the best results on drive & boost pressures...
 
Headcase98002 said:
Just some starters for me, I live at roughly 600' above Sea Level.

I turned My max EGT's got to 1500* yesterday. Once I saw that I let out and didn't even look at my boost numbers. I will say, that I don't have a drive pressure gauge either.

Ok, I took the truck out today and saw 66psi total boost and 27psi primary boost. That was with my TST on level #5.
Click to expand...

Sounds like you have a boost leak if a VP truck was able to get 1500* with a setup like that.
 
rlawless said:
I would think your ratios would be better if the primary was worked a bit harder, I would say upper 30's to lower 40's.. Your total boost may go down a bit, but higher boost does not always mean more HP.. I would install a temporary DP gauge for tuning, without a DP gauge your not seeing the whole picture..
Click to expand...

I agree with this, making my primary do more work netted me less boost, but also less drive pressure (less spread between drive vs. boost) and more hp, and what feels like a all around better running truck. But i also have a stupid turbo setup, hx35 and 75/96/1.32 LOL
 
dvst8r said:
Big hill, or tow something heavy. Or tow something heavy up a big hill. :shake:
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I can watch my neighbors dog run away for 3 days where I live...If I look hard enough, I can see the back of my own head...

And I sold our 30 foot holiday trailer last year.

All we have around here are "dips"...not really classified as a hill, as they are pretty short...I guess I'll try to find someplace around here...

Thanks!
 
Build a giant ramp? Worked for the Duke boys

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jmd025 said:
I agree with this, making my primary do more work netted me less boost, but also less drive pressure (less spread between drive vs. boost) and more hp, and what feels like a all around better running truck. But i also have a stupid turbo setup, hx35 and 75/96/1.32 LOL
Click to expand...

I think I'm going back to my Unclamped boost hose on my secondary as well.
Letting my 475 do more work.

I was making only 63-65 psi that way and now it's making 75 psi.
But my last trip to the track netted my the EXACT same MPH in the 1/8.

I will test both again at a 1/4 track but for now, less boost and more likely less drive pressure will help keep things "UNSWOLED" longer for me.

The extra boost didn't seem to make any more actual HP, even though my seat of pants told me it felt quicker on the road.
 
Big Swole said:
I think I'm going back to my Unclamped boost hose on my secondary as well.
Letting my 475 do more work.

I was making only 63-65 psi that way and now it's making 75 psi.
But my last trip to the track netted my the EXACT same MPH in the 1/8.

I will test both again at a 1/4 track but for now, less boost and more likely less drive pressure will help keep things "UNSWOLED" longer for me.

The extra boost didn't seem to make any more actual HP, even though my seat of pants told me it felt quicker on the road.
Click to expand...

You know your SOP gauge must be re-calibrated with every new truck.. That's your problem.. ROFL!

Sent from my DROID RAZR using Xparent Blue Tapatalk 2
 
rlawless said:
You know your SOP gauge must be re-calibrated with every new truck.. That's your problem.. ROFL!
Click to expand...


LOL


Yeah it must be all screwed up!
I keep expecting it to just come apart everytime i get into it anyway.
I'm perminantly "Shell Shocked"! lol
 
rlawless said:
I would think your ratios would be better if the primary was worked a bit harder, I would say upper 30's to lower 40's.. Your total boost may go down a bit, but higher boost does not always mean more HP.. I would install a temporary DP gauge for tuning, without a DP gauge your not seeing the whole picture..
Click to expand...

I'm confused. The way it is now, from a roll of 70mph to whatever I reach(110ish), it will spike up to 52ish psi and the primary is sitting at 19psi then it just whips around to 28psi and my total boost gauge slowly increases to 66psi. If I open the gate sooner it's just a lag pig. I did a boost leak test on mo day and all I found is a hole in the boost elbow from Industrial Injection. I'll check again this weekend. I really don't like the diaphragm gate.
 
Big Swole said:
I think I'm going back to my Unclamped boost hose on my secondary as well.
Letting my 475 do more work.

I was making only 63-65 psi that way and now it's making 75 psi.
But my last trip to the track netted my the EXACT same MPH in the 1/8.

I will test both again at a 1/4 track but for now, less boost and more likely less drive pressure will help keep things "UNSWOLED" longer for me.

The extra boost didn't seem to make any more actual HP, even though my seat of pants told me it felt quicker on the road.
Click to expand...

Swole,

totally different turbos here, but similar results...When i had the secondary wastegate tighter, i was making 75 ish psi, but with near 100psi drive... Primary was making 15-16 psi .Opening the gate up WAY sooner, i now see 60 psi, and 65-70 drive...primary making mid to high 20s. Made my HP goal on the dyno with my "towing tune" very easily ( very low egt) .. i like it.





and Casey, the primary sitting at 19 psi for a while , and then shooting up to 28 psi when the gate opens.... Yeah, mines not like that at all...my primary builds boost progressively starting very early and keeps sweeping up to peak exactly in the way the overall boost does. Feels a heck of a lot better to me.
 
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I just need to take a video and show you guys. The 1500* EGT's were from a dead take off to maybe 65mph. I also just installed a new timing box.
 
Instead of starting a new thread...since this pertains to tuning twins, I will put it here.

Basically a free flowing exhaust system..I mean right from the head/ heads, through the turbo, through the hot pipe, through the primary, and out where ever you have it plumbed, is what we are trying to do, right?

Less restrictions equals more power?

Need help with this:

Waste gate closed...you start to accelerate and the drive pressure starts to build as the secondary starts to spool up.
So right here, we have exhaust pressure coming into the turbo, transferring heat energy to the turbine blades, and spinning up the turbo...then exiting the secondary, on it's way to he primary. There is a pressure differential from the inlet of the turbine to the outlet...now my guess is, the more differential, the faster the turbo is going to spool up...(more heat, more energy, more power)
My reason for this is, if you where to block off the outlet of the turbine, you would be creating a restriction, which slows down the ability for the exhaust to flow through he turbine of the turbo.
Now, looking at the hot pipe...the exhaust pressure feeding the primary is in a way, the same thing...a restriction.
One thing I proved to myself, I have a QSV that I swap in and out for the primary turbo, and what I found was that with it in, it just created more back pressure on the exhaust system as a whole. Pressures and temps were up all the time. And when I pulled it out, the restriction was gone, and my drive to boost numbers came back closer to a 1:1 ratio for the primary.
Now, with the QSV in place, it was basically choking the whole system down, until everything opened up...but the temperatures say its not worth the little bit faster spool up of the primary. (in a single turbo app, these would be great.)
Now...back to the secondary.
If you have 100 psi going to the secondary, and 50psi coming out of it, you have 100psi on one side of the gates, and 50+ whatever the spring actuator is set at.
Now think about what is happening when the gates open on the secondary...if the primary is too restrictive,(too small of housing, and turbine wheel) it is a restriction, and just choking the secondary....isn't it?

My questions are: am I understanding this correctly?
To prove a point one way or the other, what would happen if you were able to get say 90 psi through the secondary, gated or otherwise...would it stall the turbo? (very small differential across the turbine wheel.)
 
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