How come.... since I put the 18.5 housing on the turbo and went to the commercial hx35, there is no turbo noise, stone quiet?

 

does the commercial hx have map width enhancers? cause i know those create a lot of whistle when ya uncover them from their hiding place under the silencer ring. just a thought

 

It has the groove but does not come with a silencer ring. Also the hose fitting on the intake is different and smoothe.

 

Did you have your hearing aids in??? I can't even hear mine with mine in.

 

Now be nice.... I'm young at heart....

 

Ya beat me to it MnTom.

Bill,
Mabye you could teach Shatzie to sound like the turbo?


~Rob

 

Now seriously, I am really curious about this. The original wastgated hx35 really wailed from 20 up to 30 at the wg setting. I replaced it with the stock hx35 for the ISB275 along with the 18.5 housing and elbow, now it never makes the slightest sound, even at 30 pounds.

I am assuming that it is moving less air as the EGT's did go up. The stock engine never made a sound with the ring out and the ScottyII until I put the larger injectors in.

I am also wondering if the '97 build commercial hx35 is less efficient than the '99 Dodge hx35. See I have something that no one else on here has, I have a 1997 24 valve

 

my guess would be less rpm on the turbo with the bigger housing. you're not getting 30 psi boost at the same engine rpm, are you?

 

It is the bigger turbine housing. Having a housing that is too big, will cause lower boost and higher EGTs at the same given RPMs that you had before the swap. Also ,check for any possible boost leaks. Did you get a new o-ring for the elbow that goes to the CAC?

What housing did you have on the old turbo, the stock 12cm2? Or a 14?

 

HID,
FWIW, I did the exact opposite housing swap you did---from an 18 to a 12 and the whistle is a lot more pronounced now. I don't even have MWE's on my h1c but I get a nice whistle even cruising at 55 with 0-1psi. Never had that with the 18. Maybe there's a restriction in your air filter, 'cause with the loads you pull, you should be fueling hard enough to get the 18 singing. Ya got me curious

greg

 

Ok first off the 18.5 turbo housing is not too big, it is just right. It gave me an increase in economy and a good increase in power pulling hills. It hangs 2 to 10 at cruise with a load and 25 to 30 depending on the rpm's while climbing hills with a load.

I had always thought that the turbo noise was caused by the intake side, hense the turbo ring to make it quiet. That side should be the same. I have no leaks or problems, does exactly what I wanted it to do with the change.

I was just curious as to why it no longer makes any turbo noise on pull.

 

HID what kind of increase in economy did you see with the larger housing !/2,1,2 mpg, dont know about the lack of noise.
Jed

 

Actually it did not work quite the way I expected on that. I thought it would increase economy a good bit at the sacrifice of power. I have a small increase in economy, probably 1/2 to 1 mpg. It actually seems to be better than that because it averages more consistant than before. So when I would get a low mpg tank full, it just hangs in there.

It was a significant increase in power though, three or four miles per hour increase on hills with a gross load. Many of the smaller hills that it would slow down on, now just are not there.

Please take note, it did cut the 0 to 60 times a bit, not as fast on take off. If you really get into it with some load, the take off in first is dismal, under light throttle of normal driving it is just fine.

For my purposes, pulling freight only, it is a good improvement. Also note that I only have stock exhaust, straight piped. I think a larger exhaust will open it up a bit. Also I have one point lower compression than a stock 24 valve engine and a more advanced cam timing.

 

Yes, the whistle is produced by the compressor blades. Have you noticed that jets are noisier approaching you than going away?
Unless I'm whistling dixie, all Holset turbos come with MWE since 94 or so.
I'm thinking the 18.5 cm² housing slows the spool until you get into the power and then the noise from the engine masks it.

Maybe I should try the big housing. I am really tired of the whistle. My hearing is really sensitive on high frequency. The wife frequency is really poor.

 

Except that the old setup was very loud on pull at 30 pounds, the engine had no chance of masking it. I am sure that there are very much slower impeller speeds which is the reason for it.