Twin Turbo's bit the big one!!!

[DBR]

Well, went for an enjoyable ride today with the better half driving the 97 twin turbo set-up, only to find out some very disturbing damage to the primary turbo! That I don't mind so much, but it was a brand new Piers' special that I had purchased for later use on my 2001 (waiting for the 36k warranty to exprire) The blades on the impellar wheel look as cavatation erroded the sharp edges down to a nice little nub. I can barely make 14 psi with it now. So, back to the drawing board!! I'll post some pictures once I yank them out, but until then, anybody have any ideas? The secondary turbo looks fine, so I don't suspect that the secondary damaged the primary.



Anyone interested in a used twin turbo set-up minus the primary? Just kidding. I'm not licked yet! I guess that I have answered my question as to whether or not they would work well together. The answer is yes, but only for a short duration!



Ok. so who has a HE1 for sale!

 

[Bob Wagner]

DBR keep your head up

you have a great design going on and the thread is great to follow.



Keep on going

 

[DBR]

Thanks Bob, just for those kind words, you'll get first bid with no reserve!



I just got back into the house after removing the twins. I have my single HX35/14cm back on. The good news is that I can use my exhaust brake again!



The turbo bearings and shaft are fine, just the leading edge of the turbine wheel is chewed. It'll make a nice ornament for the office... one of those conversation starters.



This leaves me with two HX40s and one HX35. Where do I go from here? I'm down to one HX35 and I need to keep that as a reserve. Ah well, I'll think about it for a while, at least until spring and the shop is warmer!

 

[Piers]

DBR, send that turbo back so I can do a failure report on it. Lets all see what went wrong.

 

[DBR]

Piers,

Funny thing! I was planning on driving up this weekend to show you my twin turbo set-up, just not in pieces! If you are in the shop on Friday, I will stop by to see you in the morning. Thanks Piers, I appreciate the offer. See ya Friday.

 

[MY6EATSV8'S]

DBR, I wish you could get a h2e/17cm2 for the outside turbo and use the hx40 /16 for your inside. Even better a hybrid say 40/12cm2 for the inside and a hx55/60 would be one that I would want. The problem with the latter is the 55/60's only have a 19 as the smallest housing. Still knowing the application you are going for I think the h2e/17 and a hybrid 40/12 is going to give you exactly what your looking for. Even better would be a hybrid h2e also to keep the spoolup exactly what you are looking for.

get me parts so I can get things put together for you and you won't have to change plumbing.

sorry for you misfortune.

Good luck

Adam

 

[DBR]

Thanks MY6EATS8S, I figure that the hardest part of my install was the oil pan return line. With that out of the way, fabbing piping for a new turbo shouldn't be all that troublesome. So where do I find a remanufactured H2e with a 17cm housing cheap. I have thought of putting my 12cm housing on a lathe and fitting my spare hx40 to it. I will need a turbo soon for my 2001 as my 3600 mile warranty is about due. Still need to get the trans set-up first. Thats the reason for the e-bay sale. Looking to go to Piers and Bill K this friday to see what is avaible. Sucks driving a stock 2001 auto, when you driven a hot 12 valve.

 

[John Dishong]

Hi DBR and Piers,

I have just experienced the same blade degredation that you speak of. I installed a new HX40/16 about 1 1/2 months ago. I just inspected the blades and they look like they have been sand blasted (with a large grit). I have a HX40/18 visiting Piers for repair (blew up). When I get that one back I will send him this one for repair and failure analysis. The only thing that changed at the time of installation was the addition of a plate style K&N filter into the factory air box. This took place on the same day as the turbo install. I have used K&N in the past and have never seen anything like this. I hope that I can hobble along with this turbo until I get another one back from Piers. I am very interested in any details on your twin turbo setup (pictures, piping design and turbo selection)



John,

 

[DBR]

Well after some early morning discussion with a fellow coworker, with a background in turbine / pump mechanics, we concluded that I over speed the HX35 and fatigued one or several of the turbine blades to failure causing the damage. The theory being, that once the HX40 spooled up (one run was over 50 psi) that the hx35/14 could not wastegate that volume of exhaust and over-speed the hx35. The turbo being a Piers special with a more aggressive turbine side might have helped. I can attest to the fact that Piers turbo does flow better then a stock hx35 because it sure does suck driving the truck now with just a stock hx35/14. I had been driving it for several month with Piers hx35/16 and the spool up was as good or even better then a stock hx35/14.



So any other theories?

 

[HoleshotHolset]

I like that theory, DBR... .

Since the smaller turbo is the 2nd in the 'cold side' airflow... . it is receiving some very high velocity/pressure air that it was not originally intended to.

Being 1st inline for the exhaust side also is an issue, like you mentioned... . once the bigger turbo spools, you'd like the smaller one to just kinda hang out as it doesn't have to work as hard... . but the stock wastegate can't bypass that much exhaust flow.

If it were me, I'd look into an aftermarket external wastegate setup and loose the integral wastegate. Turbonetics' RaceGate is more than up to this type of duty and is easily adjustable in-cab with a simple bleeder valve.

The larger 2nd turbo would probably be okay without any wastegate control... . just route the bypass from the external WG into the inlet of the turbine side of the larger turbo.

Better flow, better boost control... .

That's my $. 02 worth...

Matt

BTW, I know of NO turboed race cars (Buick Grand Nationals/Mustangs with 100mm turbos) that use an integral wastegate.