Competition how much boost out of twins?

[mjoppie]

i am in the process of building a 35/switzer twin setup (switzer equal to ht3b) and was wondering what i could expect for boost numbers, i got good fuel to it and dont have my head 0 ringed yet so i want to stay below 50psi. is it possible to do this? the head will be 0 ringed sometime in the spring or summer. and i also have a nitrous kit i will be putting on it later. can i wastgate the big turbo or should i adjust it with the fuel.

 

[HoleshotHolset]

Your biggest issue will be trying to wastegate the 35...



Which wastegate (internal, external) setup do you plan to use?



On edit: It's entirely possible to wastegate the heck out of any turbo setup to achieve the desired boost level. I am confident that you will be able to limit it to 50psi using traditional turbine bypass wastegating...



Matt

 

[mjoppie]

i was going to try and find a external wastegate for the 35 and blow it down into the big charger. but from there i dont know which direction to go, i should probably hold off on the nos until the heads done, right? or would it make less boost if i dumped the wastegate into the exhaust? but i know it cools egt better the other way. man i just completly confused myself, definitly need some pros advice now

 

[Partyat33]

Yes, you can limit the boost. I have a similar set up with 'divorced' twins. If you set the internal waste gate low you would be suprised what you will get. While testing I had it set so low I could only get 25 psi. Start low and work up slowly. I have mine turned down to about 60 psi now. Good Luck

 

[Mark_Kendrick]

i was going to try and find a external wastegate for the 35 and blow it down into the big charger. but from there i dont know which direction to go, i should probably hold off on the nos until the heads done, right? or would it make less boost if i dumped the wastegate into the exhaust? but i know it cools egt better the other way. man i just completly confused myself, definitly need some pros advice now

There are several gates that will suffice. Almost all aftermarket gates are 38mm or bigger and will work. try http://www.tialsport.com/, http://www.turboneticsinc.com/wastegates.html (i'm a dealer for them), http://64.225.76.178/main.htm.

 

[mjoppie]

so does that mean wastegate both turbos or just the little one? if i only wastegate one how do i control the overall boost of the system? would a internal wastegate on the little turbo work? how would a 12cm housing spool in a twin setup? i have a 16cm but its not wastegated. just thinking out loud. any ideas.

 

[Mark_Kendrick]

look at this ... http://www.texasdieselworks.com/Compounds.htm



It has a good picture. You wastegate the little turbo and let the big boy run. w/a 26cm housing you won't over spool it.



I almost never use anything but 9,12,14 cm housings in my twins so, yes a 12 will work well.



Twins are a little slower to spool than the smallest turbo by itself so if a 16 is a bit laggy in a single it'll be more so as twins.



FWIW,

Mark

 

[mjoppie]

so using what i have on hand, the stock housing 12cm wastgated, and the switzer comarison to a ht3b and a 26cm non wg you dont think it will produce more than 50psi or are you saying that it would be safe to put in blow off valves to control it to 50 psi and yes the for some reason the 16 was quite doggy on the bottom and never opened up on the top but the top end was a different problem i have fixed now. this is looking better and better the more you guys help me Oo. oh and one more question if i hit it with a 100 hp shot of nos will it pop the head gasket or should i hold off until the head is 0 ringed?

 

[Mark_Kendrick]

no pop off valve, just a properly adjusted WG. nos could be a bit hard on the HG if you don't use it properly. you shouldn't need it though.

 

[mjoppie]

would the stock wastegate on the 12 work? how do you control the boost out of the big turbo by wastgating the little turbo? the little one would just feed into the big one and drive it without controling it. or are you talking about using a external wastegate and dumping it into the downpipe? tryin to visualise what your saying but im kinda lost now, and what is a divorced twin setup anyway?

 

[Jim Fulmer]

Matt..... use your PM.



Info, I ran a PDR HT3B/26 and a stock 35 with a 16 and and 18. 5 housing, both worked great till 65 psi and the 16 went out fast (drive pressure) at 70 psi the 16 was at 82 drive and intake temps went up 35 degrees from 65-70... . it was done, that's why I went to the 18. 5 with very little difference in spooling. Small housings are fine at low boost levels but in the higher ones they go south fast... ... ..... what do you want, quick bottom end or big topend... ... . BOTW my current combo is no different at 60 psi... still 1 to 1 but at 80 she is barely over 1 to 1 and still in the game.



Without a doubt that combo of yours will make big power if it's tuned right.



Jim

 

[mjoppie]

so with what i got i probably shouldnt look towards putting any more fuel to it until i get the hg done, by the way has anybody ever heard of a 450hp marine injector? a local pump shop wants to make my stock injectors into 450hp injectors by changing the tips, but i have never seen them or heard of them before. if there out of the c series would they work or is the spray angle off? how close are they to a 370, it seems like a good idea in theory but have a hard time seeing how they would work.

 

[mjoppie]

i just found my stock 12 housing and was wondering if it could be ground open on the inside of it to work in a twin setup, as a wastegate? would it flow enough to take the load off of the 35? im just lookng for a decent spooling set of twins and to keep them at 50 psi until mid next summer when i get the head ringed. i have been told that i could use pop off valves in the intercooler hose to keep it at 50 without overspooling it, is this right?

 

[Gypsyman]

This is all new to me but would a 4LHR work as a bottom with an HX35? Is it equivilent to an HT3B? I'm just starting to learn this stuff so go easy on me.



Richard

 

[mjoppie]

i took the back off my stock 12 housing today, is it possible to open the wg hole to be a effective wg in a twin setup? can you put a bigger flapper on it to make the hole even bigger? just thinking of the alternatives to a external wg and the piping that goes with it. and would a stock wg work or should it be sompthing like a banks big head? figured id try and put you turbo gurus in the spotlight for a bit. :-laf

 

[Mark_Kendrick]

Stock WG generally do not flow enogh to control boost on a 450+hp motor. You will be pushing gasses for more hp out of the motor than the housing will flow.



Go ahead and use the external gate. it will give you the EGT and boost control you are looking for.



FWIW,

Mark

 

[mjoppie]

ok, but is there any way to bore the wg hole open enouge to do it? i see a lot of twin setups that use a internal wg and always wondered how they do it. i know where your coming from on the external but an internal would be much easier in my eye.

 

[Mark_Kendrick]

ok, but is there any way to bore the wg hole open enouge to do it? i see a lot of twin setups that use a internal wg and always wondered how they do it. i know where your coming from on the external but an internal would be much easier in my eye.

They use a lager exhaust housing so the WG doesn't need to be as big. The external is better than hacking on a internal any day of the week and twice on sunday.

 

[mjoppie]

oh i see, so there using like a 14,16 or maybe even bigger? what could i expect for hp out of a setup like this? i was hoping for 450-500 w/ 75hp shot of nos. y/n? thanks for the help. have you ever heard of using co2 in the intake tube to help lower egt temps? a friend was telling me how gas racers use it and kinda made me start to wonder.

 

[Mark_Kendrick]

You can make 440hp on a hx35/16.



with hx35-12/HT3B twins you could make 470-490 w/o ANY nitrous. With a set of injectors and a little shade tree work you'll be in the 500's.