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Discussion Starter #1
I'm currently running twin old school cast wheel Borg S366sx3's tractor turbos with the 80/73 turbine .91ar on my 4.6 4v mod motor th400 ucc converter drag only car. the current borgs are a bit laggy, but do ok when I leave off the brake at 4500+ anyways. I'm thinking about stepping into some newer turbo technology and was looking at the vsracing line of billet turbos

What turbine would you guys recommend for a small cubic inch motor in the 30-35psi range as twins? the 6766 runs a 74/66 turbine and the 6782 82/75 turbine. Im looking for as fast spool as possible obviously, but want to make sure I don't run out of steam up top where this thing lives most it's life (7500-8000 rpm)

I'd love to get my hands on a set of precision 6766's, but man they are pricey. even the newer billet borg 369sxe's supercores have crossed my mind as my current turbine housings will fit them, but havent heard much results about em. I dunno, just thought I would throw this out there.
 

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I have some SXE-369's with Bullseye SS v-band housings for my Stock Block Shootout car but haven't ran them yet. I found the Super Cores on the interwebs for under $700 each and was all in for under $2K for the pair complete if I remember correctly. The 366's make really good power for the money. A couple people have said the 369's didn't go quicker/faster on their combos but I think they will really shine in the upper range above 25psi. Bullseye has a line of budget friendly Borg based turbos you may want to check out. Bill Devine has been really good to me and I kinda regret not getting the complete turbos from him. The great thing about Bullseye is if they spec you a turbo setup and it doesn't perform as stated they will make it right. Get a Chinese turbo dealer to do that. I know Chinese turbos have gotten a lot better the last few years but I try my best to buy American made whenever possible. At a minimum don't give money to a communist country that stole or reverse engineered the design from a reputable company. I'll get off my soapbox now. Good luck with the combo and be safe.
 

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Discussion Starter #3
I have some SXE-369's with Bullseye SS v-band housings for my Stock Block Shootout car but haven't ran them yet. I found the Super Cores on the interwebs for under $700 each and was all in for under $2K for the pair complete if I remember correctly. The 366's make really good power for the money. A couple people have said the 369's didn't go quicker/faster on their combos but I think they will really shine in the upper range above 25psi. Bullseye has a line of budget friendly Borg based turbos you may want to check out. Bill Devine has been really good to me and I kinda regret not getting the complete turbos from him. The great thing about Bullseye is if they spec you a turbo setup and it doesn't perform as stated they will make it right. Get a Chinese turbo dealer to do that. I know Chinese turbos have gotten a lot better the last few years but I try my best to buy American made whenever possible. At a minimum don't give money to a communist country that stole or reverse engineered the design from a reputable company. I'll get off my soapbox now. Good luck with the combo and be safe.
Thanks for the info TurboII. I sent an email over the bullseye to see what they can do for me, didn't realize they were a local Michigan company!
 

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We dealt with Bill at Bullseye, he's very helpful and informative- answered all our questions and prices are very fair, our next turbo will come from him too. He actually upgraded the big single we bought to a billet compressor wheel free of charge as the cast wheels were temporarily out of stock.
 

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Discussion Starter #6
I guess my main complaint with the cast wheel borgs is the time it takes to go from launch boost on the brake to my target boost after transbrake release. I attributed this to the big heavy cast compressor wheel of these old school borg's? I'd love to be able to be all in by .5 second after release if need be. Currently it takes near 1.5 seconds or more to reach peak (5.5psi launch to 13.5 target). Now some of this is likely tune related as its a fresh setup and still working through the tuneup, but after seeing some of the boost curves ive seen in datalogs on similar combo's with as big or bigger comps wheels makes me urn for that fast transition to peak boost early on.

I get that I have a lot of turbine and compressor for this little motor, and thats why I was thinking about a 6766 billet wheel option with the smaller turbine? I'm pretty green dealing with turbo specifics, so I could be completely off base with that assumption.
 

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The Chinese stuff is hardly cutting edge either though.

Moving to a better unit with lighter wheels will help, moving to a unit with smaller lighter wheels may help.

a 6466 would spool better than a 6766, and still likely outperform the old 366 everywhere, hence a cheap try would be a 73mm turbine 364SXE which could retain your existing turbine housings.
Although the smaller turbine 68mm might be another option...albeit requiring turbine housings.

Problem with turbos...is there are far far too many options these days.
 

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Discussion Starter #10
Likely another china turbo, but like you said not much info on it. They list a T51R ? "compressor mod" , but don't say a single word about what the hell that is lol. I've noticed none of the china turbos ever list any type of compressor map or hell even lb/hr flow specs, usually just a simple generic HP rating if that. Hopefully hear back from bullseye on Monday, not sure if they'll be in my budget or not. Wanting to stay in the 1K range per turbo, and get the best one in that range for my combo
 

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I would definitely look at the tune-up and boost control before passing judgment on any turbo(s). To get the boost ramp you are looking for it may need a more aggressive tune-up but I would probably look at the boost control first. The turbo(s) have mechanical/dynamic limits as to acceleration. Less weight is always good if it doesn't sacrifice reliability. However you can make sure they are getting 100% of available drive energy by pinning the gates shut with full commanded CO2 pressure at the release of the transbrake. This will max out the current turbos potential on the combo and show you on the datalogging how quick mechanically they can build boost. After seeing the mechanical limits of how quick it can make boost. Once this is figured out you can see that ramping CO2 faster than they can make boost is a waste of time and effort.
 

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I am not far from starting on my SXE369 system and was making some flanges for the Bullseye housings so I can run full aluminum exhaust from turbine housings. So here's some pics of the 369's disassembled and also a PT6765 that are for a customers project. I took a few pics of both to show the physical differences. Only 2mm on the compressor wheels but the amount of surface area is more substantial than the pics show. The newer compressors have more vertical height that seems to be one of the key features of having higher pressure ratio.
100425

100426
 

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The T4 Bullseye housings are dramatically larger than the T3 Precision housings. A/R size is only comparable between housings of the same series and that isn't always true in all cases, especially between different mfgs. 1.00 A/R T4 Bullseye and .83 A/R T3 Precision. 2.25" inlet vs 3.00".
20200628_004214.jpg

100452
 

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I think only the turbos PT designates as Gen 2 CEA have been redesigned. IMHO I don't think some people have seen increased performance with the 369's vs the 366's due to not running higher boost pressure where the 369 begins to shine. The cast 366 compressors are no slouch and move a lot of air, I just don't think they have the pressure ratio the 369's have. I guess time will tell.
 

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Discussion Starter #17
Excellent info TurboII and Stevie, I appreciate all guidance I can get.

Next time out, I will command max dome pressure on the gates after T/B release and see how the cast 66's do in the transient from launch to target and go from there.
 

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I am not far from starting on my SXE369 system and was making some flanges for the Bullseye housings so I can run full aluminum exhaust from turbine housings. So here's some pics of the 369's disassembled and also a PT6765 that are for a customers project. I took a few pics of both to show the physical differences. Only 2mm on the compressor wheels but the amount of surface area is more substantial than the pics show. The newer compressors have more vertical height that seems to be one of the key features of having higher pressure ratio.
View attachment 100425
View attachment 100426
Can you get a picture of the inside of the compressor housing?
 

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Yeah no problem. I'll try to post them today if possible, assuming I can get into the shop. We are pouring concrete today and may not be able to get on it till the weekend.
 

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Pics as requested.
106067
 

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