DodgenIt

Hey guys.
So I just picked up a brand new non waste gated Holset 35/40 hybrid and Im wonderin what kinda boost I might be seein with whats in my sig. I dont have it in yet cause im wonderin if I should have a waste gated exhaust housing put on. Also I might be adding Bosch 275's in the next months and would eventually like to have DDP 3's(110hp)

HTT told me I will easily see 35 lbs with only my J/A and shouldnt go over that for safety for the turbo, but Gillett Diesel said they'd be suprised if I could hit 35lbs with just the J/A and would have room to add injecters.

Ive heard of alot of guys goin over 35lbs with this turbo and not havin a problem.

Whats the optimal boost range for a 35/40 hybrid? and should I be worrying about getting a waste gate if I get bigger then stock sticks. Dont wanna be blowing my head or turbo ya know.
TIA, Ian

Big Blue24

The optimum boost will depend on what elevation you're driving and what optimum means to you. Maximum Hp will occur somewhere around 45-50 psi. Maximum efficiency will occur somewhere around 25 psi. Maximum longevity will be obtained by keeping boost under 40 psi and never barking the turbo.

FYI, 40 psi at 4200' is like 36 psi at sea level as far as airflow and pressure ratio. Although some guys may get away with short 45 psi bursts at sea level, you might experience turbo failure at 45 psi at high altitude. The higher you are, the faster the compressor has to spin to build the same gauge boost pressure. High compressor RPM can lead to compressor wheel failure and excessive bearing wear.

If I were you, and just running Hot Juice and RV Injectors, I wouldn't worry about limiting boost, your fueling will limit max boost somewhere around 40 psi. I would just train yourself to let off slowly so you don't bark the turbo, especially when you're pushing a lot of boost.

DodgenIt

Thanks Big Blue, those boost numbers where exactly what I was lookin for. I think it'd be safe to say with how I drive, ill prob be right around 25 lbs most the time, and only be seein higher when racin. Ive heard the problem with barkin this turb and will for sure be watchin to not let it do it.

I have another thread goin in here "HX-35 questions," that thread has a bit more info in it, check that one out maybe you'll have some more thoughts to help me with haha.

Ian

BarryG

My 01 has rv275's, juice, smarty and a DTT auto. I am running one of the PDR 35's which is a hybrid as you are looking at. I am at 6300' elevation and routinely drive up to 10k' elevation. I run empty most of the time but also tow from 4k to 15k through the same stuff. When I switched from my hy 35 to the pdr 35 I gained what I was looking for but there is more lag not bad but more.

My turbo is wastegated and I have never seen over 38psi. I think it is wastegated about there but not sure. Since it has always been wastegated I am not sure if I am out of fueling or if the gate is opeing. My egts are good. I rarely see over 30-32psi. I guess what I would call my high normal boost is in the mid to upper 20's, as in regular driving not racing or wot but getting on the freeway quickly, steep hill or something like that. I typically run the juice on 2 or 3 and the smarty on 4.

cumminsdriver635

What size non wastegated exhaust housing does it have on it? We will need to know this before it is possible to have an idea about boost.

If you arent sure, look at the turbo. Right inside the inlet of the exhaust housing where it bolts to the manifold, there will be a number stamped inside somewhere. Look around until you find it, and it should just be a 12, 14, or 16, and that will let you know which one you have.

If you have the non gated 12, boost will be fairly high, and I honestly wouldnt run a 12cm housing without a wastegate. The 14cm will be a little small when you get injectors I think, but should be good for now, and if it is a 16cm, it may be a touch laggier, but i think it will be the best non gated housing to run for your overall horsepower goal. A 14cm wastegated housing would be a nice housing for that turbo because it would spool good, and you could control boost. Honestly though, if I were in your shoes and on a budget, I would think hard about trying to find a stock HX35 wastegated 12cm housing. Take the backing plate off, and drill through the center divider so that the wastegate could gate all 6 cylinders. Put it on the truck with a boost elbow, set boost where you want it and you are good to go. I have heard they work good enough to keep boost at 35psi or so between 450-475hp at that level.

I would try and keep boost no higher than 40psi. I ran my HX35 at 40psi for a good while. Just do like the others said, and try not to bark it. It wont be too hard to keep from barking it, and it helps the longevity quite a bit.

Anyways, look and see what housing you have, and keep an eye out for a good used 12cm gated housing for cheap. I think that may be your best bet since you are still wanting good spoolup, and to be able to control boost.

Eric

DodgenIt

Thanks for all this info guys.

My hybrid has a 12cm non gated housing.

You think I should get it swapped for a 12 or 14cm gated housing and that would get me where I want to be with this turbo? fyi, wanting to add stage 1-3 sticks.

Also, from my other thread, HX-35 questions, I would assume this hybrid would make a good compound with a s400 over it? Like you said a HX35 would right.

BarryG what size exhaust housing does your 35 have?
Also, have you done any good WOT runs with your chips turned up?
Just wonderin if I would be over doin it on a 1/4 mile with juice on 6, and maybe RV 275's throwin in.

cumminsdriver635

Personally, I would swap the exhaust housing before you put the turbo on. A 12cm non wastegated housing is going to spool good, but it will make a lot of boost with no way to regulate it.

I would find a good stock 12cm wastegated housing. That should easily let you keep boost at or under 40psi and also have the same spool as the housing that is on the turbo now.

A hybrid HX35 gated at 40psi should handle what you have with some small sticks pretty good, and it may still get hot on hard 1/4 mile runs with that setup, but honestly, if you are looking for decent performance with a single turbo, EGT's are going to be fairly high on hard runs. That said, if you dont mind overfueling it a little, the hybrid HX35 will make some good power. Probably enough to put your truck in the 13's.

I just think you will have a hard time keeping boost down with a 12cm non gated housing.

And as for twins, that would be a great top charger in a set of twins. Something like an S471, or an HT3B would be great under it.

Eric

DodgenIt

Cumminsdrvr you the man. Thanks for the info and explination to follow. Thats pretty much exactly what I was thinkin, it just reassuring to hear someone else back up what I got goin in my head .

Im stoppin at Gillett today and should get this thing goin!

BarryG

Dodgenit:
My housing is a 12cm gated. With my dtt auto and altitude I honestly was afraid to go with a 14, I HATE LAG. A 14 may work fine for me but with my use the 12 seems to work good. I might very well think differently if I was racing or pulling at the track. And to be honest again WOT for me is pretty rare. I dont drive like grandma or anything but it pulls and gets up to speed so good I just dont need to do it often at all.

To answer your question I dont doubt it might be over doing it with everything turned up for the 1/4. Will it survive I think so, is it the best application for that maybe not. However there may be other alternatives such as a cam that as a daily driver would benefit as well as at the track. That is what I ended up doing. My issue was towing in the mountains (elevation 8000 and above) up the twisty curveys at 40-55mph then need to get on it the smoke would roll and the lag would be felt big time however egts would be ok. In town I would have to roll into the throttle gently to avoid a big smoke show from a stop light or sign. Not long ago I put in a cam. It did not give me big hp gains if any. It did however make my turbo much more friendly in my eyes. My smoke is down considerably and lag is also down noticably and throttle response is up.

Each turbo, each housing and each of the multitude of combinations of them has their pros and cons. When I was first looking at upgrading my turbo several years ago I was talking with a well known diesel guru about it. He made a statement to me that has sort of stuck with me in regards to my truck ever since. It was really take a look at how you use your truck on a regular basis. For example- do you want a turbo that will do well at the track, that will be of benefit when you are racing which will be less than 1% of the time you are driving the truck or would you rather base your turbo on how you use your truck 99% of the time. Obviously the answer to that question depends on who you are, how you use your truck, your driving style and what your goals are with your truck. For me the answer was I want my setup to be the best for how "I" drive 99% of time and compromise on the remaining 1%.

DodgenIt

BarryG I agree with your last paragraph. I would rather have my truck do what I bought it for.. Work and DD.. But I for sure want it to hold its own on the track too haha.

Im planning on swapping to a 12cm gated housing, I think that will hold me just fine even if I do get the 275 sticks or maybe mach 1.6's. Ill just hold off on bigger sticks till compounds are lookin like a more likely event. Even then I dont think I'll go bigger then 150 hp sticks, Prob more likely 110's and if I still want more fuel for the turbo's, maybe stack a smarty instead of bigger sticks. Thats quite a ways down the road if even in the direction ill take my truck.
Heck once this turbo is on with stage 1 sticks, I might just be so pleased with over all performance and driveability, I may start workin on looks and leave power alone.

Well see, Everyone says they'll be done after the next mod, Few really ever are though

cumminsdriver635

So when do you plan on getting this thing on? You have to find a housing for it first? You wont have any problem keeping boost down with the 12cm gated housing. I would drill the divider before you put it on though.

Eric

DodgenIt

Well I was planning on putting it on tomorrow, but yea I'm gonna track down a 12cm gated housing first. I think Gillett diesel will work with me on that part.
There a local shop and Im there bs'n quite a bit.

Rich (owner) told me the price dif between gated and non housing is about $200. Im hopin that since my hybrid is brand new, he'll swap it for me and just charge me the differance even though it was HTT that built it.

Im gonna try to make it down there monday, if not then, then wednesday for sure. And Me and my buddy will put it in next sunday.

Now Im not super keen on turbo mechanics, what do you mean drill through the center divider? Does it not gate all 6 cyls already??

nate_88

Ian, you won't be pleased with overall performance after twins and 110 sticks. You know you'll want more power once I do compounds and 200s because I'll be whoopin' you down the track!

Swarthy Dago

X2, but i'm getting the HT3B on the bottom and the stock 35 on top. I need more air. that 35 gets hot ! i'm only seeing 30 psi

cumminsdriver635

The center of the exhaust housing is divided like most of them are. The wastegate only wastegates the rear 3 cylinders because of this. Most people just take the cover off the back of the housing, take off the actuator arm, flip the wastegate flap out of the way and drill as big a hole as you can straight through the divider. This helps to be able to control boost. You can probably do pretty good just gating the rear 3 cylinders, but it wont hurt to gate them all.

Eric