Competition Boost From Twins

[Big MAK]

What boost numbers do you get from twins? Is it true that the actual work of each turbo in the twin config is about 1/2 the measured boost in the engine? What boost numbers are going through the intercooler with twins?



Thanks! ... . trying to figure out if I should buy a single or go all out on the twins...

 

[BPINE]

In my case the Big or first stage turbo makes 30 lbs of boost when I see 50 lbs in the manifold so I assume the second stage or small turbo is making 20 lbs. I would say cut to the chase and call Piers and order a set of twins.

 

[willyslover]

Mark. . you'll be in the line LOL

 

[HOSS]

Max recall on the SPA guage in the Red Rocket shows 92lbs of boost.

 

[Jim Fulmer]

Blair if your 3B is making 30 psi that that shows what the 23cm housing is doing, most of the time the 3B's run at 35 on those setup's with a 26 housing but at a much higher overall boost. On the Twin setup's it gets more into the maps, a turbo is stupid, it only knows what to do after you tell it what to do, saying that at 14. 7psi (standard day) the map is one thing but in Blair's case for example he is adding 30psi on top of the 14. 7 and that is what the top turbo see's and the map makes a hard right turn out of the picture.



Now lets look at my set, it's the exact setup as the PDR 40/3B Twins except I have the Big Brother on the bottom, on a normal full power run I see 80 psi at the hat and the B/B is at 36 psi and tow pop offs are wide open, so looking at that math and data from the dyno with the pop off's capped it should come out to about 95-100 psi if full in-closed and without any adjustments, but think about it for a sec, the B/B is about 1/3 bigger than the 3B and it's map is allot different so it's moving more air making more overall boost when the 40 is setup the very same on both setup's, at 40psi on any of the setup's the 40's gate is wide open and now it's slowing the 40 down and most of the air is being by-passed to run the Big Charger with the top charger doing nothing more than moving air and not compressing it or not much, as long as the drive pressures are the same in both systems then the 40 is still at the same boost unless I'm lost here. Either way you or anyone else needs to ask yourself the million dollar questions, were do I want the power to be as well as driveability and EGT's, then turn around and see what your pocket book will handle.



2 1/2 years ago Piers and I had this conversation when I was running a stock 35/16, after I built my first Twin setup it dynoed at 440hp.



Jim

 

[Ryan]

With an HX35 w/ 16cm housing and a BHT3B w/ 26cm housing I max out at 70psi at the intake, at the same time the 3B is making 22psi. My set up does not use a wastegate, I don't have enough fuel to need one.

 

[BPINE]

Originally posted by Jim Fulmer

Blair if your 3B is making 30 psi that that shows what the 23cm housing is doing, most of the time the 3B's run at 35 on those setup's with a 26 housing but at a much higher overall boost. On the Twin setup's it gets more into the maps, a turbo is stupid, it only knows what to do after you tell it what to do, saying that at 14. 7psi (standard day) the map is one thing but in Blair's case for example he is adding 30psi on top of the 14. 7 and that is what the top turbo see's and the map makes a hard right turn out of the picture.





Jim

Jim I have no idea what you just said please try to reread it and explain it again. Thanks for your help buddy. FYI the boost will go higher I have had it somewhere over 65psi but I was using 50 psi as an example.

 

[Big MAK]

Thanks for the discussion; helps me figure it out. The follow on question was how the 'eck you measure the total pressure in manifold. Is digital the only way? Also; to keep from blowing gaskets what's involved in o-ring'ing? The second question in the starter post is still on my mind; what kind of pressure is the intercooler seeing if the manifold is seeing; say; 90psi? Hmmm; wonder if I can squeeze a 2004 intercooler into my 2003.



Thanks! This is _very_ helpful for someone thinking about getting serious with the upgrades!

 

[BPINE]

Originally posted by Big MAK

Thanks for the discussion; helps me figure it out. The follow on question was how the 'eck you measure the total pressure in manifold. Is digital the only way? Also; to keep from blowing gaskets what's involved in o-ring'ing? The second question in the starter post is still on my mind; what kind of pressure is the intercooler seeing if the manifold is seeing; say; 90psi? Hmmm; wonder if I can squeeze a 2004 intercooler into my 2003.



Thanks! This is _very_ helpful for someone thinking about getting serious with the upgrades!

I have a 0 to 80 psi mechanical boost gauge. The first thing you need to figure out is exactly what you are going to use the truck for, twins are no differn't than a single you still need to size them for the application. O ringing the head is no small job it takes special tools and a lot of time, I think Piers gets 12 hours labor and he has done more than a few.

 

[Big MAK]

The application is (don't laugh ) sled pulling, trailer towing, daily driver. To get good drivability it looks like twins are the only way to go -- and still expect to be competitive sled pulling w/o imploding the turbo every few runs. Or running one so big it isn't really streetable. So I guess I've convinced myself to drop the bucks on twins. How many hours will it take me to get to Piers from Omaha? ... . I can put anything together but o-ringing the head is not something I care to tackle. Cha-ching; I swear I was going to start small; and now ...



pro-street DHRA sled pulling says "stock engine". Is the engine considered 'modified' if it's o-ringed?

 

[MCummings]

A turbo only multiplies what it see's.



At idle, on a standard day, the turbo "see's" 14. 7PSI, but is not spinning fast enough to compress at any significant rate.



Go wot, in the meat of your power band. For conversation sake, we will say you are really working your turbo at a compression RATE of 2x.



The turbo takes the 14. 7psi atmposphere, and turns it into 29. 4PSI.



Put that same turbo in a twin setup, and at the smae point in time, it will be "seeing" the extra boost from the big turbo, so now, instead of 14. 7psi, it actually "see's" 30PSI, and it takes that pressure, and compresses it 2x. It will make 60 PSI, while working just as hard as it was as it was in a single, making 29. 4PSI.



Make sense?



The more boost your "big" turbo makes, the easier it is to make higher boost numbers.



The OE intercooler is only good to 80~ish PSI, and it will develop leaks. I've ran mine higher than that, but have not tested it for leaks.



My turbo's are setup to make some good boost.



My big turbo can run around 50PSI (3. 4x atmosphere)

My little turbo can operate at the same ratio, and higher. . up to ~70. (4. 7x atmosphere)



In Theory, I could make 235psi of boost with my setup. Lucky for me, I'll be only a little over half that.



Merrick

 

[Jim Fulmer]

Sorry Blair, what I was trying to say is the towing Twins you guys are after more bottom and midrange so the 23cm housing is more suited for that application, if it had a 26 or 32 housing it would run slower at that boost level and create lower boost and not be as responsive.



Now on the compressor maps statement! You are now force feeding the little turbo were if it was being run by it's self it would have to pull air in, the turbo map is based on pulling air in and not having boosted air feeding it so now the map is totally different, if you were about to measure it's boost after the gate opens up you would see that it is not doing much at all, or that is the thought.



Jim

 

[BPINE]

Thanks Jim and Merrick, that is sorta what I thought but I got a little confused after you posted Jim.





Big Mak looks like you just need a regular set of PDR Twins and call it good. I don't think the drive will be to bad for all the fun you are going to have. This is JMO, I am not an expert but hope to learn fast. I worked with Nowel for years on twins but untill you have your own and really get to play it is all just theroy.

 

[Proram]

With my HTT 35/40 -16 and a HT3B with a 26, and Bully 5's the box on 2/3 it'll make 80 at will, Put the 8's in and 5/5 with the gate set high i've seen over 100 numorus times, (once i got the HG sorted out,) temps in the 1300 range, hevent dyno'd yet w/ this combo, but my guess is 630/640 based on my last pull,

we'll see soon as i get a chance to get to Kauffmans,

New Shop/Buissnesss taking up all my time.



Scott

 

[John L]

Does anyone know how much overall boost adjustment the PDR twins (Hx40/HT3B) have? I know the website says 70lbs but whats the minumum? I really want to get a set of twins but the stock head gasket is stopping me. I was hoping with a waste gate adjustment and setting the blow-off valve low enough I could reduce the boost to around 50 lbs and when I have more time & $$$ I could drive up North and get the head done.



John

 

[willyslover]

waste gates will determin what you see. . up to you to adjust to what you want. . and yes you can set it up for 50 +/-

 

[Forrest]

Originally posted by willyslover

Mark. . you'll be in the line LOL

So ... taking the plunge I take it?



Forrest

 

[Big MAK]

I'd really like to take the plunge; it's just way more then I was planning -- money wise and in terms of "how much truck" I was looking to build. So I'm still investigating single turbo configurations and staying in that "street" class (vs. "pro-street" with twins). I'm thinking to be competitive in pro-street you really have to 'hang it out there' and make all the power you can find; whereas the street is a bit more laid back. Perhaps I'm totally mistaken there -- another reason I'm leery of jumping into pro-street as a rookie.



Looks like I can get into a clutch; etc; that can handle 'street' levels of power for what the twins would cost by themselves AND I don't have the money or time to get to B. C. this year. So putting twins in actually eliminates me from being competitive since I can't turn on the power to really use them (head not O-ringed).



BUT looking at it from just the perspective of what's the best plan to build up the truck -- twins right off the bat is a smart way to go.



Always a million and a half factors to weigh!



It's kind of looking like I more-or-less "have to" keep with a single setup to be able to compete this year. I don't have the Camaro to race; I need my speed/power fix; I got the shakes ; aggghhh!!!!! Oo.

 

[John L]

Willyslover- thanks for the wastgate info...



John

 

[Ryan]

Originally posted by Big MAK

I'd really like to take the plunge; it's just way more then I was planning -- money wise and in terms of "how much truck" I was looking to build. So I'm still investigating single turbo configurations and staying in that "street" class (vs. "pro-street" with twins). I'm thinking to be competitive in pro-street you really have to 'hang it out there' and make all the power you can find; whereas the street is a bit more laid back. Perhaps I'm totally mistaken there -- another reason I'm leery of jumping into pro-street as a rookie.



Looks like I can get into a clutch; etc; that can handle 'street' levels of power for what the twins would cost by themselves AND I don't have the money or time to get to B. C. this year. So putting twins in actually eliminates me from being competitive since I can't turn on the power to really use them (head not O-ringed).



BUT looking at it from just the perspective of what's the best plan to build up the truck -- twins right off the bat is a smart way to go.



Always a million and a half factors to weigh!



It's kind of looking like I more-or-less "have to" keep with a single setup to be able to compete this year. I don't have the Camaro to race; I need my speed/power fix; I got the shakes ; aggghhh!!!!! Oo.

If you are wanting a large sinlge for the street class I would call/PM JR Adkins and ask about an HX55 Hybrid. The hybrids use an HX40 Exhaust housing so they will bolt right on to the stock or ATS manifold and use an HX40 down pipe. You will be able to make as much boost, with the right amount of fuel, as most non o-ringed heads can handle. They are still driveable on the street, I ran one for 5 months on my daily driver before I decided to go to twins.