Holset HX40 vs rb25 neo

[stevie-wunda]

Hey guys.

I'm pondering whether my Holset hx Super40 is too large/laggy for my liking.

It has a garrett .63 exhaust housing on it. And is the super40 = 7 Bladed Billet wheel.

Atm my rb25det neo engine is running; exhaust, fmic, 550cc injectors, bosch external fuel pump, and Link G3 computer.My front exhaust cam seal is leaking so i'm thinking that whilst I change that I may as well put an adjustable exhaust cam gear on, which shall help laggyness, yes?

When do you guys think it'll come on boost? In comparison to a garrett gt3076r or if you've had no experience with them,in comparison to a gt35/40.

I'm deciding whether or not I should sell it and get something a bit smaller.What are they worth btw? 2nd hand, no play at all though..

Help would be awesome! Cheers.

[Kalypso]

are you comfortable with compressor maps?

you know the liter / displacement of your engine, get the map and you'll be able to see the boost levels at the varying rpm's.

I can explain this further, but for now its late... and im tired....

[stevie-wunda]

Yeah, i'm semi comfortable..I know how to choose what power level at what boost for an xlitres engine. Like know if it'll be too 'surgy' or if it'll be running in choke mode kinda thing.But I couldn't really say I know how to work with it when looking at rpm's.I'll try locate a compressor map and link it to this auction?

[Kalypso]

ya compressor map is a must.

its pretty easy I'll show you.

[stevie-wunda]

Ok heres one map. It's not very detailed. The tallest map is the super 40;

http://x8c.xanga.com/aebc7b66c...1.jpg

[stevie-wunda]

Ok, I found this to be very interesting from what someone has posted on another forum..

A GT3076r vs an hx super 40;



What do you think? I'll look for more info tomorrow
Modified by stevie-wunda at 4:55 AM 7/27/2009

[Cjmartz2k]

How in the world did you get a garret .63 housing on the back of that thing? What exhaust wheel is it? IMHO, the best part about Holset's wheel designs is how well the turbine wheel flows compared to the spool characteristics.

Anywho, my full on HX40 with a 19cm housing (about a .90 a/r) is at 15 psi by around 3.5k rpm and 22 psi by just under 4k rpm in 4th gear. I have a short runner intake and no VCT either, so both of those things should hurt spool.

I don't know what kind of spool times or horsepower you are looking for. Maybe tell us what your application is?

[Kalypso]

no, thats a dyno sheet.



1. download this.. HERE! and in ~CID~ enter in 150.

that's the displacement of your engine

2. Ok now you have lbs/min - airflow for your motor

so you see rpm, and the corresponding airflow. lbs/min is on the base of the comp map



3. now move you're way up to the Centerline of the map and at its lowest point is when you hit boost.

pressure ratio corresponds to boost pressure.

2.0 = 14 psi3.0 = 28 psi 4.0 = 42 psi

and thats it.

X line is lbs/min Y line is pressure ratio / boost.

Pressure ratio means. ( atmospheric pressure + boost / boost ) they do this because boost pressure varies at diff temps and altitudes.

using this understand you can plot your exact boost pressure throughout the powerband.

I dont know how the surge lines and choke lines factor in though, maybe you can explain that better, I havent delved into that yet.

Good luck

[stevie-wunda]

The inside of the housing has been machined out a little bit to fit over that steel 'cap' that it's meant to slip over underneath =D

oh s***, my bad. shows how much I know.

Oooook I semi get that! Lets just clarify so I know what i'm doing. haha

Sooo at 3500rpm my engine will be flowing 25.4 lb/min, so I look at the compressor map/dyno chart and go up from 24.5 lb/min.. and at that point in the rev range it should be hitting 1.4(pressure ratio) = 0.4 bar @ 3500rpm?! I feel like i'm wrong here..?

And Cjmartz2k, do you have an hx40, not super40? Going on what you've said that'd probably be good for me! I wouldn't want it to be any laggier.

I'm looking for 260-300kw. I don't really mind as long as it's more than 260kw, and not insane amounts of boost (ie 23psi+). And it's no laggier than say 18psi AFTER or at 4000rpm.

Cheers for the help so far guys!

[Kalypso]

I dont use Bar i use psi... because thats all I know but (easy to convert)

but ya:

at 3500 rpm you get 4psi... (19 total including atmosphere)at 6500 rpm you get 17psi... (31 total including atmosphere)

so the math seems right, but this turbo is laggy. find the exact map you want and check it again, but as of now...

its a laggy setup... unless you bore out the block
Modified by Kalypso at 5:28 PM 7/28/2009

[Cjmartz2k]

I dont use Bar i use psi... because thats all I know but (easy to convert)

but ya:

at 3500 rpm you're getting 19psi... at 6500 rpm you're gettimg 31psi

so the math seems right, but this turbo is laggy. find the exact map you want and check it again, but as of now...

its a laggy setup... unless you bore out the block

Define laggy. Laggy compared to a stock turbo maybe. That's better spool than a GT35r and most people are making more power with lest boost with 40's when compared to a GT35r.

OP, it's a "super 40" with the 60mm 6 blade inducer on the compressor wheel.

[stevie-wunda]

By 3500 = 19psi you mean inclusive of atmospheric pressure right? So in theory it'd be 14.7psi less? = 4.3 psi?Sorry i'm just a tad confused, and yeah i think that'd be the right graph? Don't know though.

I have the 7 bladed billet wheel, super 40. Hmm starting to get more confused.

Cjmartz2k how do you think my turbo will compare to a gt3076r?

[Kalypso]

By 3500 = 19psi you mean inclusive of atmospheric pressure right? So in theory it'd be 14.7psi less? = 4.3 psi?

YES! you're right, I edited my last post to correct that. thank you.

but still laggy, you can get faster response from a smaller turbo.

gt35r

[Kalypso]

ok, on the gt35r

at 3000 you get 5psiat 6500 you get 24psi

that looks like a fun turbo....

look for a smaller holset im sure they have something with a map like this.

How High are you planing to REV? the turbo you choose will be based on whether you're reving to 8000rpm, or 6500rpm

[Cjmartz2k]

By 3500 = 19psi you mean inclusive of atmospheric pressure right? So in theory it'd be 14.7psi less? = 4.3 psi?Sorry i'm just a tad confused, and yeah i think that'd be the right graph? Don't know though.

I have the 7 bladed billet wheel, super 40. Hmm starting to get more confused.

Cjmartz2k how do you think my turbo will compare to a gt3076r?

OK, 6 blade = pro, 7 blade = super. It's just marketing names. The 6 and 7 blade are supposed to flow the same, with a slight edge going to the 6 blade at higher boost levels. The HX40 is a much bigger turbo and shouldn't really be compared to a GT30 anything. It's the contemporary to the GT35r.

As far as that calculator goes, it's not correct here, or at least the numbers getting punched in to it aren't right somehow. I've already said, I make 1 bar (14.7psi) by 3400rpm, and and 1.5 bar by 3900rpm.

The HX40 has consistantly out spooled a GT35r with the same size exhaust housing on every dyno chart I've seen, but the difference is small. Yes, if you consider a GT35r laggy, you would also consider a HX40 laggy.

OP--for only 400rwhp, if you are interested in holsets, an HX35 would easily knock down those kind of numbers with much quicker spool than the HX40. Keep in mind though you have that teenie tiny exhaust housing/wheel, so I'm sure you'll already see much quicker spool times than me.

[Kalypso]

As far as that calculator goes, it's not correct here, or at least the numbers getting punched in to it aren't right somehow.

ok so im doing something wrong... I'll reread the Garrett how-to again

pressure ratio is screwing me up, but I think

3500 rpm - 19psi6500 rpm - 31psi

was right... I'll try it again elsewhere

[stevie-wunda]

Cjmartz2k do you have a dyno graph you can post up?

I honestly do think that something isn't quite right with that calculator too. Although it could be because the map is for the large truck exhaust housing?It's saying that at 5000rpm it'll be hitting .75 bar.. like 10psi. Definitely not right, not sure if it's the calculator or the fact that it'd be a large exhaust housing.

[Kalypso]

exhaust housings do make a big different tho

the calculator comes from enthalpy tune, and its been around so I think its fine.but until you've mastered Compressor maps keep trying! this is the best way to generate accurate predictions.

you should join other forums as well so you can learn the most. and most important go to garretts website and read turbo tech 101 (advanced section)

[Cjmartz2k]

Kalypso, yeah, those numbers make much better sense. I think 31 psi would come on a lot sooner, but 19 psi would sure be possible with a smaller exhaust housing. Mine's a little on the larger side. Still not huge, but not tiny. As soon as I am past like 1.2-1.3 bar, the needle just flies up, so I'd bet 31 psi by around 4500rpm. Not going to find out with out some race gas though

Sorry, no dyno's here on Okinawa. I can try and get some vids in the next couple of nights with spool times and maybe some more 1/4 runs with the Gtec and let you guys see. That's about as good as I can do. I have to go downstairs now and fix my damn clutch pedal bracket. The freaking metal of the firewall that the bracket bolts too has broken again and I have NO CLUE how I'm going to fix it.

[stevie-wunda]

ok hmmmmmmmmm..

Yeah you think you could get some vids please? Like a 3rd gear pull from about 2000rpm(rolling) and then just put your foot to the floor? Also the same with second gear? Would be awesome if ya could man!..

I'm going to be using it for a bit of drifting, so kinda just trying to sum up if it's going to be too late in the rev range for that.

Cheers boys!

[Cjmartz2k]

K, I'll see what I can do. a second gear pull is kinda useless though, even on drag radials. I'll try to get a 2nd, 3rd, and 4th though.

[stevie-wunda]

sweet as!

would be much appreciated =]

[Cjmartz2k]

So yeah, i kinda got in a little trouble with the cops last night out playing. Vid is going to have to wait a couple of days.

[stevie-wunda]

Oh no! That sucks dude.I feel guilty now! lol. Yeah sweet hope you don't get in too much trouble eh.

[Cjmartz2k]

Nah, don't. I was going to be screwing around anyways. Not a bad ticket actually since they didn't actually SEE me doing anything. Told me right off the bat I was getting a parking ticket even though I was in the car with the engine running. They were rude, so we screwed with them back. They asked me if I spoke japanese (in japanese) and I was like "huh?", so they called a translator who took 1.5 hrs to get there (keep in mind this is 3am). As soon as he got there, I started answering all his questions in japanese. Boy were they pissed. Then we started taking pics and posing with the cop car and asking if we could sit in the back seat since it was hot and they had a/c. Good times $120 though

[Kalypso]

hilarious

[stevie-wunda]

hahaha.. crack up. i'm surprised you didn't get arrested!

wheres these vids at? lol

[Cjmartz2k]

I'll try and get some tonight and upload them tomorrow. It's just going to be me with my s***ty point and shoot and some peak values on the PFC hand controller.

[stevie-wunda]

haha sweet mate!.. just keep relaxed and that hand should stay steady. lol.make sure you don't get snapped too!

[Cjmartz2k]

Sorry, we have a typhoon here right now so no vids for the next couple of days. Soon though, I promise. I've got a couple other people asking for them on another board also, so I'll get to it soon.