7 blade hx35 or 8 blade hx40 in bep

[holsettsi]

im planning on building another dsm, ive owned over half a dozen dsms and im wanting to out do my last build.

the build will consist of a built 6 bolt bottom end, most likely 8.3:1 so i can run a little more boost on pump gas than having higher compression.

the head will have 1mm oversize valves, port and polish work and kiggly beehive springs. and for cams gsc s2s.

intake manifold is a magnus street and a vrsf fmic. it will be tuned with link v3 and on 1750 injectors in case i ever switch to e85.

i will drive this set up a LOT on the street and would like to make the car daily drivable. so next comes turbo choice. i am torn between the 7 blade hx35 and the 8 blade hx40.

my 1/4 mile goal is 11.5. both turbos essentially are rated at the same lb/min BUT they will both be in bep housings. the cams powerband is 4 to 9 but i only plan to rev to 8 or 8500. will both turbos hold boost solid to redline? if so, the obvious choice would be the hx35 for the 600 rpm earlier spool. but will it die off at top end?

sorry for being long winded. i broke it up so its easier on the eyes

 

[little-razcal]

I vote HX-35. It will be better for the street and definitely will hold to redline. I've followed my friends build which is similar consisting of Hx-35, 272's, 8.5:1, ect...and it is a beast on the street and hold its own at the track. With the bolt on housing he is trapping 130 and has gone 11.3 with no slicks and a ton left to be had. The HX-40 is a good turbo also, just thinking of the best bang for the buck in terms of powerband, goals, streetability, ect...

 

[dexterholland04]

I think my definition of a street setup probably is way off to what "normal" people think; but I thought a HX-40 in a T3 housing was the best street setup I ever ran. I've had a 20g, and a .55 BEP s362 as well and the HX-40 beasted them both! Just my $0.02...

I want to say on 28 psi of boost, I ran 11.40's without even breaking a sweat on 1.9 60 fts! On 34 psi, the car went 10.92 at 129! I think the HX-40 is one of the easiest turbos to go fast on. On 38 psi, the car went 10.30's at 136-137. You'll find 11's are boring...and a HX-40 would give you all you need to grow into.

 

[JusMX141]

If you must use the bolt-on housing, I vote HX40. Better turbine flow, tons of compressor variations depending what boost level and spool you're looking to achieve.


If you'd consider a T3 manifold, I'd suggest looking at the HY35. The factory 9cm single-scroll turbine housing which clears the block even on the tightest-clearance manifold setups. It has a smaller turbine wheel than the HX35 yet uses the same compressor. Spool is about the same as a TD06 20G but this turbo offers tons of growing room where the 20G tops out at 45 lb/min. You would need a custom-fabbed o2 housing for this turbo, but if you look in the right places you can get the turbo for $250 or less, and a new T3-flanged cast manifold should be sub-$200 as well. Do some research and find who builds the best knockoff wastegate for under $100, and there's a 500hp-capable setup that has been proven into the 10's by a few cars for +/- $550.

Just be sure you're getting an actual HY35 and not the HE341 which many guys try to pass off as a HY35 as it uses the same rotating assembly. The 341/351 have a 90* elbow on the compressor outlet, the HY35 does not.

 

[holsettsi]

so in terms of flow, the hx40 will put the hx35 to shame? im trying to stay clear of the t3 housing because i dont want to fab up an o2 housing/downpipe.

so would a 6 or 7 blade hx40 in the bep housing be the best bet for allowing room to grow?

i want something that will spool fast on the street yet not be a lag monster.

I will O-ring the block also. So at 35psi will the hx40 outshine the hx35?

 

[JusMX141]

so in terms of flow, the hx40 will put the hx35 to shame?

By 12 lb/min or so, yes.

so would a 6 or 7 blade hx40 in the bep housing be the best bet for allowing room to grow?

Grow how? Not sure I understand.

I will O-ring the block also. So at 35psi will the hx40 outshine the hx35?

Why is it so hard to figure out that a larger turbo will generate more airflow?

 

[andyb2637]

When he says grow, he mean in terms of Hp range I think.

 

[holsettsi]

By 12 lb/min or so, yes.

Grow how? Not sure I understand.


Why is it so hard to figure out that a larger turbo will generate more airflow?

by grow, i mean not running out of turbo as i continue to upgrade.

also, its not difficullt to grasp the concept, im just having difficulty in figuring out what will net better results. a turbo that spools faster and makes power sooner or a turbo that spools later and makes more power? where is the compromise? thats what im having trouble with.

if you say the difference in spool wont be noticeable between the 2, then i will be more opt to go bigger and not look back.

sorry if im repeating anything, i just want a complete understanding before i commit.

 

[JusMX141]

by grow, i mean not running out of turbo as i continue to upgrade.

Gotcha. Well that's not likely to happen with the HX40.

also, its not difficullt to grasp the concept, im just having difficulty in figuring out what will net better results. a turbo that spools faster and makes power sooner or a turbo that spools later and makes more power? where is the compromise? thats what im having trouble with.

Consider the difference in spool versus the difference in airflow between the two turbos....400rpms or so to stand to gain 10-12 lb/min. That's the same spool difference that exists between a Small 16G and Big 16G, yet the Big 16G is only more potent by 2-3 lb/min.

if you say the difference in spool wont be noticeable between the 2, then i will be more opt to go bigger and not look back.

There's obviously a difference. You're comparing a HX35 with a 70/60mm turbine and 78/54mm compressor to a HX40 with a 76/64mm turbine and 86/60mm compressor. You can't possibly expect similar spool conditions to exist between the two.

 

[bastarddsm]

T3-flanged cast manifold should be sub-$200 as well. Do some research and find who builds the best knockoff wastegate for under $100,

Just be sure you're getting an actual HY35 and not the HE341 which many guys try to pass off as a HY35 as it uses the same rotating assembly. The 341/351 have a 90* elbow on the compressor outlet, the HY35 does not.

1. The god speed manifolds require some grinding and machining an angle (2*)on the turbine housing to clear. Not a big deal, but need to be prepared. The treadstone may be ok.

2. Don't be scared of the internal gate. I use it and it works great!

3. With a little welding cutting and grinding the HE341 can be made to work. The covers are interchangeable too.

 

[JusMX141]

The god speed manifolds require some grinding and machining an angle (2*)on the turbine housing to clear. Not a big deal, but need to be prepared. The treadstone may be ok.

Ricky ran into that a few years ago with one of those manifolds on his old SC6031E using a .82 T3 turbine housing. I figured all of them would be the same, but certain knockoffs clearly are not machined the same as you've addressed here.

The true Turbonetics manifold is a guaranteed fit if you're lucky enough to find one-simply grind a little flat spot on the back of the HY turbine housing where it contacts the balance shaft tube on the block and you're golden.

 

[holsettsi]

well it sounds like the small difference in spool would be worth the hx40s power capability. i suppose go big or go home. ill go with a 6 or 7 blade hx40 then

thanks for your help