Wastegate size??

[Morse]

I need to know what size wastegate to go with on my twins. . It's a sledpuller 66 for my small turbo, with the big brother large turbo. . I know bigger sounds better, though what would do the job easily could be another. . I've heard as small as 38, and as large as 50. . Maybe right in the middle at 44 would be good. . Any help would be appreciated...

 

[Diesel Freak]

use the SP66 wastgate to controll the SP66. Correct me if I am wrong, but the SP66 has a dual port wastgate.



To eliminate the need for those crappy hot water reliefs, and to make your system perform correctly, use a large WG on the hot pipe to control the Big Brother. I would use a Turbonetics NewGen. This way you can dial in both turbos, and keep boost in the sweet spot. You will need to play with the NewGen a bit with an external boost controller to get the Big Brother above 20 PSI. The extra effort will be worth it!!!

 

[BPonci]

I believe they use those so called crappy hot water reliefs for a safety valve. If there using them to control boost there tuning the system incorrectly.

 

[Diesel Freak]

I hope they are used as a safety on the occation that a wastgate fails. If at any time under WOT operations a safety relief lifts, something is wrong and as you have already said, the system is poorly engineered and horribly inefficient.



(Politicly correct for "It's CRAP")

 

[swankmetal]

i'm gonna go out on a limb here. wouldn't "blow off" valves lead to an overspeed situation?

 

[BPonci]

Your correct. Rotor overspeed.

 

[Morse]

Would a 44,46, or 50 external wastegate be best. . I don't want to go large just because it sounds better. . I just want a good quality unit that will do the job. . As an end result, I'd like to run at least 80-90 pounds of total boost. . It's getting closer to being finished. . I just want to have a smile the first time it's dynoed. . My luck, I'll be cussin'. .

 

[Diesel Freak]

i'm gonna go out on a limb here. wouldn't "blow off" valves lead to an overspeed situation?

you betcha!!!!

 

[Diesel Freak]

Would a 44,46, or 50 external wastegate be best. . I don't want to go large just because it sounds better. . I just want a good quality unit that will do the job. . As an end result, I'd like to run at least 80-90 pounds of total boost. . It's getting closer to being finished. . I just want to have a smile the first time it's dynoed. . My luck, I'll be cussin'. .

well, here is the dilemma. If you go too big, you will need to shim the spring, or use an external boost controller, or both to go higher in boost.



if it is too small, you may not be able to keep the turbo from overboosting.



If it were me, I would go big..... it allows more room for more fuel in the future.

 

[Jim Fulmer]

You could get one of these http://64.225.76.178/main.htm they are 44mm this is the one I ran on my first setup, or you could get one of those mega dollar New Gen gates but I personally don't see a need in it, you won't vent that much air off, although I run a 40 on top (obviously less that a 66 wheel turbo) I've never seen my boost past 90 and there are no pop off's installed. You will more than likely be able to control it with the top turbo, I think with one like a Phat Shaft using a dual gate you should be able to by-pass enough air. It has been said by Pias Bell that all Twin setups need two gates and non-gated housings, but I like the gated ones on top so there not so doggy on the street... ..... most of us actually drive our trucks.



Jim

 

[Morse]

I'm a little unclear as to setting the wastegates. . Do I set the small turbo at 40-45psi, and then install the big brother? Would that control the total boost as well, or just limit what the small turbo output to the large turbo. . I'm definately new to all this.

I have to decide today what size to go with. . It's between a Tial 44 or Tial 46. . The 46 is $150 more than the 44. . At this point, $150 isn't a huge deal, though I don't want to throw money away on something I don't need. .

 

[Diesel Freak]

It has been said by Pias Bell that all Twin setups need two gates and non-gated housings.

Jim

BINGO!!







Morse, here is a copy of a post I made for a guy over at NWB.

Your TiAl wastgate should have two ports in the diaphragm housing. One to open the valve and one to shut it.



Install a fitting in the air pipe between the primary and seccondary turbos (primary boost).



Off this fitting make a "t". Off one side of the "t" send a line to a boost gague preferably one that goes from 30"Hg to 30 PSI.



On the other side of the "t" send a line to the side of the SECCONDARY TURBO WG that holds the valve shut.



Use the SECCONDARY boost on the "open" side of the diaphragm to open the wastgate.



With this setup, if the PRIMARY WG is set for 20 PSI, and the seccondary is set for 10 psi, the total boost the system can make is 30 PSI... . if the wastgates are large enough.



From here you can start adjusting the SECCONDARY pressure signal to the WG with an external boost controller (basicly an adjustable bleed valve) to start making more pressure.



Primary wastgating is easy. Just use primary boost to open the primary WG.



If the primary turbo is limited to 20 psi, and you get to 50 psi off the seccondary, that is a good stopping point. Both turbos are running the same pressure ratio.



If you bump the primary to 25 psi, then peak seccondary boost should stop at 68 PSI. if you bump the primary to 30 psi, then seccondary boost should stop at just over 90 psi.

 

[Jim Fulmer]

but I like the gated ones on top so there not so doggy on the street... ..... most of us actually drive our trucks.



Quote to a Quote..... Cliff your too much fun



Remember that most of use knuckle heads on the street are trying to do the best of both worlds, thinking that you can have a set of Twins run at 10 psi(600 degrees) on the road and spool in 2 seconds to 100 psi (100 psi drive pressure) is a pipe dream... ... give and take, were you add to one you take away from another, and were doing it on a tight budget... ... ... . one thing to remember about Twins, guys were doing this in the 80's on tractors... ... ..... I do remember this!



Jim

 

[Morse]

I don't hear a lot of people speak of drive pressures on other threads. . Is it really something for us street guys to worry about? Most say they just throw the twins on and adjust the wastegate to the boost they want, with no mention of drive pressure. . I've heard of others speak of dual wastegates, though I've never actually seen someone running dual external wastegates. .

This is a street truck. . If it breaks down, it's going to be sitting for a long time. . I only have 12mm studs. . How hard can I push this thing without breakage? I've had some say 85 pounds of boost, and others say they've seen over 120 and not to worry about it. .

I ended up having Poole build the twins. . My turbos are on the way there as we speak. . I would have went with Adkins or Schied, though I it was hard for me to find a way to get the truck to either of their shops. . Then it was between Kendrick and Poole. . Kendrick was great to speak with, and offered me the best price. . I started looking at pictures on the web, and I really liked the V band clamps Poole uses. . He's going with all V band clamps on mine. . He offered me the option to run a 44 or a 46 wastegate, though recommended going with the 44. .

 

[Bpostel]

Morse... Mike Smith is running a set of J. R. s' twins, they are a liittle "55" on top with an HT4C on bottom with a 50mm wastegate. At 80psi of boost he has 60psi of backpressue. This truck flat out screams!

 

[justinp20012500]

There is a huge amount of improvement to be made on the dual port gate on the SP66.



The holes are only about 7/16" in dia. The flapper that covers them is more like 15/16". You can open up both of the holes to 3/4" and flow alot of air. You can also make a plate that will allow the flappers to open up at a much steeper angle, thus allowing more flow.



Cliff what would two 3/4" holes flow? How would that compare to a 40mm external gate?





Justin

 

[Diesel Freak]

a 40mm hole has a cross sectional area of 1. 94"



two . 75" holes have a combined cross sectional area of . 88"

 

[Morse]

Bpostel, I would have really liked to have Adkins build them. . He gave me a great price, and was really polite and full of knowledge. . The problem is that I live and work in Florida. . My truck is in my old hometown (in Kentucky)where I grew up at a buddies shop. . It was approximately 4-4. 5 hours each way to take the truck. . I would have to pay someone to haul it for almost 18 hours of driving and fuel. . It would end up costing quite a bit. . This made Adkins and Schied out of the question. . Kendrick and Poole were the choices I ended up having for a kit that could be shipped to me. . Poole was a little more costly, though I really liked the thought of all V band clamps holding it together. . That's all it boiled down to. .

I ended up going with the 44mm tial...

 

[Bpostel]

I forgot to mention on Mike's truck, he's making 60psi of boost on the low pressure charger. The 50mm wastegate is doing it's job well.

 

[Diesel Freak]

I forgot to mention on Mike's truck, he's making 60psi of boost on the low pressure charger. The 50mm wastegate is doing it's job well.

60 psi on the bottom charger? and your peak boost is what? 304 PSI?



Geeze, give me a break!!!!