Eric, he already had the turbosmart WG actuator with 26lb spring, max preload, and wgdc at 100% in the top end. Yet still dropping boost in low gears and overboosting in high gears (I'm assuming he didn't want to run 40psi in 4th and 5th and overspeed the turbo). Many people pushing this turbo have the same issue apparently. I haven't seen any of them try a 4 port.

 

This is the biggest problem I see with IWG configurations especially with a large compressor like this that's intended to have a dynamic boost range. It would be nice if instead of having a flapper they could somehow integrate a tial valve into it.

 

Depends upon how you plumb the 3 port... and if you can configure your output as such. I have ability to dial in feed-forward boost by gear and then enable the PID after it. So you shouldn't see such a drop in boost, if you are it's just a matter of being capable with a keyboard and the software to tune it. I know it physically can do it, because I've done it. If the boost is tapering because it's out of compressor, then your turbospeed should reflect that. I suspect they aren't logging turbospeed and no real way to correlate whether they're out of compressor or having boost control issues. tspd sensor eliminates that guesswork.

 

Eric, are your 2 port TurboSmart actuators sealed on the bottom port?

 

The 7163 map in matchbot shows a highest speed line of 150,500 rpm. If you calculate what tip speed that is on a 71mm dia wheel, that is 560 m/s. Same as every other EFR compressor map shown from the 7064 and up. You can do the conversion from rpm to tip speed in matchbot and get that answer. I prefer using my ancient HP 11C calculator for things like that haha keeps me in practice.
So anyway, I don’t necessarily buy the idea that max rated rpm for the 9174 is 128K just because its turbine wheel is rated for 128K. Like I said in post #3285, “there should be a max shaft speed that considers the whole turbo - compressor, turbine wheel, bearings, everything.” Since you have been getting your info from BW, I should probably just talk to the same person to get their explanation for it all. Can you tell me the name of the person and where he/she is?

 

I think your missing the point of the speed rating. The turbine wheel will fail way before any other components fail due to the material they're using.

 

The 2 I've had both leaked a little out the shaft seal.

 

Def no leaks or a premature opening or leak from the BOV, that's all constantly checked. Also a boost leak results in over speed across the board (if in close loop BC) not just in the last 30-40 milliseconds of a pull.
I was having fueling issues and that scenario only happened when doing multi gear pulls past 32-34psi. I could however do single gear 40psi pulls with no issues.

 

No I am not missing that point at all, and I think from what we have heard in this forum all along, the turbine wheels do seem to be the weak point.
But there is nothing hard to understand about me wanting to know who the source of your speed rating info is at BW, which I have asked for a few times now. As an engineer, I have to reference my information all the time. Or if I don't, and somebody asks me about my source, I don't try to avoid it. I never feel defensive about being asked for my source. So I am asking for the same from you. If you don't want to give me the person's name and contact info, well, just say so. No worries. I appreciate you posting your logs, experience, and opinions. So thanks for that.

 

I'm not defensive, is just that your asking me to give out a contact info that's not mine to give out. Here's BW's 2014 catalog: http://www.turbos.bwauto.com/files/p...bo_Catalog.pdf

That has all the speed ratings for the turbos. It also has their phone number so if you still need to contact someone about it you can.

 

Version 3 of the 2015 catalog is here:

http://www.turbos.bwauto.com/afterma...spx?doctype=16

 

Ok thanks. I can understand that you would rather not give out a person’s contact info, especially in a public forum, so no problem.

Thanks for the link to V3 of the catalog. I had only seen the 2014 catalog before this.

Their catalogs are nice, but I don’t see max turbo speeds listed, except as implied by the highest speed line shown on the compressor maps. The V3 catalog still does not have a page for the 9174. I was hoping that the "Technical Training book" might have a discussion on the subject of max turbo speed "rating" but I don't see one. That is a really nice document though. So yes, I will try to find somebody by phone who can delve into the engineering aspects of it with me.

 

https://www.facebook.com/fraserbrock

 

i found some scattered data on the 6758 on i believe a 2L motor, but not sure how it crosses over to an evo? anyone know anything about the "indycar" 0.64 housing? im still trying to plan out a setup, i think the 7163 is too big for the power i need, but im not sure of the full capability of the 6758...

 

Anecdotally speaking from the dyno graphs I've seen from 6758 and 7163 the spool threshold is not really different between the two setups. Probably due to the small difference in size and the mft wheel on the 7163. The transient response on most efrs are described as so quick it doesn't matter, I assume the same holds true for turbos that are so close in size.