Patrol 4x4 - Nissan Patrol Forum banner

41 - 60 of 75 Posts

·
SUI GENERIS UTE
GQ Ute 1990 Silvertop
Joined
·
5,850 Posts
Discussion Starter #41
Having the gate so close to the nozzle like that is not a good idea. it generates fluctuations in drive gas to the nozzle making it difficult to maintain constant shaft speeds when the gate opens or tries to adjust bleed off close to peek boost set values. External gates work well if they are away from the turbine volute.
 

·
Registered
Joined
·
268 Posts
Having the gate so close to the nozzle like that is not a good idea.
I also was thinking along similar lines, but then again it's not that much different to an internal gate setup either so I'm guessing they aren't exactly ideal too.
Anyways the thought of running the external gate coming off the turbine housing like that came to me when I was planning a gateless setup and that would be my backup solution for if I got the sizing wrong or if I just didn't like the way it worked as gateless. So hard trying to figure out what size everything needs to be, but I guess that's half the fun. Speaking to a few turbo companies to discuss my options for turbine housings and custom flanges to suit my application but the S200SX-E supercore looks promising and with 6 turbine housing ranging from 0.83 - 1.27a/r I should be able to find one that'll suit my needs.


 

·
Registered
Joined
·
268 Posts
Learnt something new today about blade surface roughness and its effects on airflow which lead me into learning about reynolds numbers which I had never heard about before. Photos below of two examples of what I was researching

Smooth blade surface
16105814_1516612875033808_4897582587208418706_n.jpg


Vs rough blade surface
62568979_2650801888281562_2884405018432110592_o.jpg
 

·
Registered
2001 GU ST TD42t coil cab (gold)
Joined
·
4,042 Posts
Aaaannnnnddddd??????????
 

·
Administrator
GUII ZD30DI Wgn
Joined
·
44,166 Posts

·
Registered
Joined
·
268 Posts
Lol sorry I got busy with work and ran out of time to write anymore. In the papers I found it definitely had gains in efficiency compared to the smooth surface but only very small, less than a few percent. But the real advantage was in the ability of the point milling to have a much more efficient and better aerodynamic blade profile than what is obtainable with the more common flank milling.
 

·
Administrator
GUII ZD30DI Wgn
Joined
·
44,166 Posts
Lol sorry I got busy with work and ran out of time to write anymore. In the papers I found it definitely had gains in efficiency compared to the smooth surface but only very small, less than a few percent. But the real advantage was in the ability of the point milling to have a much more efficient and better aerodynamic blade profile than what is obtainable with the more common flank milling.
Thought you might have been checking whether we were taking notice ;).
 

·
Registered
Joined
·
268 Posts
Thought you might have been checking whether we were taking notice ;).
Haha no not this time, I just like to share what I learn and think is interesting. I'm still a complete novice when it comes to all this tech/engineering but I don't know what it is about this kinda stuff, I just can't stop trying to learn and research as much as I can. I know there's people on here that are experts and work with this stuff daily and I definitely don't expect any of them to give their hard earned secretes away so I try not to bother them too much and go off on my own to learn it all myself and do my own experiments. I appreciate the help they give me though ;)

I've just started ordering more turbo parts for another project/test which I can't get off my mind to do with wheel design. I've found a supplier of custom billet wheels cheap and I plan to order a few types and test the difference between split and full blade designs as there's very little written about this. I've got a 11 blade and a 6+6 blade already coming in the mail but also have 5+5, 7+7 and 10 blade earmarked. Not sure how much I'll be able to do anytime soon as some drunk decided to crash into my car the other night when it was parked outside my house 😔
 

·
Registered
Joined
·
268 Posts
Who are you getting to change and balance the wheels?
I'll be changing the wheels over myself as I'm also using this project as an exercise to learn more about turbos and how they are assembled. For the balancing I happen to live close to a local shop which has a couple of Cimat balancing machines so that'll be no troubles if I even bother to go to that level of precision. This whole turbo and wheels is less than $400 in parts so I don't think I can justify spending $100 each time to balance it just to drive it around for a few days to test each wheel.
 

·
Registered
nissan
Joined
·
6,180 Posts
This whole turbo and wheels is less than $400 in parts so I don't think I can justify spending $100 each time to balance it just to drive it around for a few days to test each wheel.
I've heard of other people installing their own wheels and not bothering to get them balanced. So far the failure rate is 100%.
 

·
Registered
Joined
·
268 Posts
I've heard of other people installing their own wheels and not bothering to get them balanced. So far the failure rate is 100%.
wow! That's crazy, I've heard the opposite and some of these were from turbo builders themselves. If I was planning on running it long term I'd go to the expense of balancing and doing it all right but for just doing back to back runs I'm willing to take the risk. Besides I already have a pretty sweet turbo which I normally run full time this is just for an experiment on a cheap turbo combo testing different wheel designs backyard style lol.
 

·
Registered
nissan
Joined
·
6,180 Posts
This would probably work better on a ball bearing turbo because I think the unbalanced rotating assembly flogs the sleeve bearing in the centre housing pretty quickly.
 

·
SUI GENERIS UTE
GQ Ute 1990 Silvertop
Joined
·
5,850 Posts
Discussion Starter #54
I think if you are starting with a generic turbo like a real garret or a real IHI then changing a very light billet comp wheel that has been singly balanced, the risk will be lower due to the fine balance done on the very much heavier turbine wheel and shaft. Also to note as the comp wheel size gets bigger and heavier the risk gets higher and higher. I am pretty sure changing comp wheels over 71mm willy nilly you would see 100% failure in a very short time frame. This would also depend on the turbine wheel and shaft weight and its initial low speed balance. The finer that balance is would lower the risk as well.

A cheap turbo, well that's a risk to start with but its possible to do some experimental testing with multi wheels to see what happens. You would want a journal bearing i think just because they are deemed a little bit more robust for very low speed vibrations only, there is no saving grace at 100K though neither any grace at 65K over a ball system... i think you would be pretty safe doing this on a BW EFR though due to their very much superior engineered CHRA.
 

·
Registered
Joined
·
268 Posts
The journal bearing Toyota Supra turbo I'll be using has a brand new Melett CHRA and it's only spinning a smallish comp wheel 46mm inducer / 65mm exducer and a heavy (nearly 300grams) 68mm inducer /52mm exducer turbine. The CHRA comes already balanced with the factory heavy cast compressor wheel and with VSR results, unsure if its also been low speed balanced too. The billet wheels I've got coming are the same size as the factory cast wheel but being billet they should be much lighter and they are also balanced on there own.

This all might be a while off testing now due to my front end all being smashed up by the drunk who smashed into me the other night but I'm hoping it'll all work out sooner rather than later 🤞
 

·
Registered
nissan
Joined
·
6,180 Posts
This all might be a while off testing now due to my front end all being smashed up by the drunk who smashed into me the other night but I'm hoping it'll all work out sooner rather than later
Sorry to hear about your misfortune. Good luck with the experiments when they go ahead. I'll be interested in what you conclude.
 

·
Registered
Joined
·
268 Posts
CHRA and the first comp wheel design arrived today. I'm quite surprised how light the new wheel is, couldn't find the right sized socket to remove the factory cast wheel to compare. The extended tips of the new wheel makes it look much larger than the original, it's a bit higher in blade height too but the most noticable difference that really stood out to me was how much smaller the nose/shaft is that the blades come out from.

IMG_20191218_161938.jpg


IMG_20191218_161535.jpg


IMG_20191218_161608.jpg
 
41 - 60 of 75 Posts
Top