Engine is a dart shp based 400ci sbc, 9:1cr, 225cc 23* heads. I will be getting a custom turbo cam made, I dont "think" 400ci will have a problem lighting them, just looking for some opinions based off real world experience or whatever else. Not looking to set records, just a nice street/strip car that'll run with the best of them when that time presents itself.

 

Why not just twin 76/65 turbos? 78/75 was pretty much created so you could run a T76 on a V8 without having to go with a T6 frame turbo. At 3.25L per turbo it'll take a whole lot of converter to get a 78/75 up into boost.

 

The 76/65s makes for a crappy turbo with an 11mm split between the compressor and exhaust wheels. A set of regular cast wheel s366s are high on my list too, very good turbos i've heard for about $580 or so a piece. The vsracing billet 78/75 is VERY intriguing at $555 a piece.

 

If you're looking at cast s366's why not get the vs racing version for $379 a piece? https://www.vsracing.net/catalog/pr...=1391&osCsid=a7bce2b139dbce7a13c2e142cbb75fa5

Looks like he has a billet version on his new site on sale for 550.
https://turbo4less.com/product/vsr-66-73-billet-2/

 

I did see those....I wonder how they compare to the real borgwarner turbos

 

These are pretty much the turbonetics 72/68 clones....only difference is the billet as far specs goes:

https://www.ebay.com/itm/Rev9-TX-72...2-0AAOSwA4BbKD-L&_nkw=rev9 turbo billet&rt=nc

 

Not sure what they did to screw up the 72/68’s but I wouldn’t suggest them. Me and 3 buddies all bought sets of them for twins on Ls engines. They performed very poorly and aside for mine, all of them leaked oil within a short time of being run. Performance as on par with the T6 cast S475 with much slower spool times.

I Agree the 76/65 is a crap turbo. Also the S300 clones have a goofy clipped exhaust wheel that looks nothing like a the true borg wheel. That said I’ve seen 2 cars on FB running then as twins and putting up good numbers.

Have you considered the $400 cast 78/75s from VS? The billet craze is outa control and the cast wheels flow more than enough I’d think?

With the lower compression it will depend a ton on the converter IMO. Set it up to rev and it should spool them without issue.

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Thanks for that valuable input forcefed, never thought the rev9 72/68s would stink that bad lol. I really like the s366s except for the larger physical size and weird turbine outlet vband size over the average smaller t4 stuff, but i could fit them if i had to. I'm gonna look into some cast wheel 76/75s or the cast 78/75s you mentioned. I know their rep is good, bad or just ok depending on who you ask but On3 has a new t6 94mm with an 11 blade billet or cast wheel compressor option mated to a 103mm turbine wheel, 1.30ar, vband turbine inlet/outlet. I havent seen or heard anybody using it yet, but the billet wheel option for $1200 is a heck of a deal IF it performs anywhere near what the specs says it should. I would seriously consider going to a single setup if a turbo like that pans out at that price!

 

It was a shame... I was expecting much more from mine. Buddy still went 8’s with them on a 4.8, but he had to run a TON of boost. I’ have to go back and ask but I’m wanting to say 28lbs. It’s almost like the housings didn’t fit the wheels snugly enough so they were really inefficient. Then the cartridges started failing on all of them...

I’ve been drooling over those new large frame On3 turbos. The SBE LS record holders are running the real deal versions of those down in the 7's at 170++. I asked about the billet VS cast and they did say the compressors were completely different. Smaller hub, longer blades, and extended tips on the billet. Might actually be worth the cost difference in that case. They also come with the super cool light weight SS v-band housings that drop quite a bit of weight. I’d go that route over twins if you have the space.

 

I've been seriously considering going to a single now after seeing those large frame On3 turbos. I would also do a nice fmic now that there'd be less cold piping with a single. If do stay with twins, the s366s are the clear frontrunners right now from a performance per dollar standpoint. I'm NOT paying $1500+ each for precision's overrated and overpriced t4 junk

 

I had twin cast wheel ON3 78/75s on an LQ4 6.0. They would make 9 lbs. in 2.4 seconds on the transbrake. PTC 9.5- 15-0- 45* convertor and .627 229 at .050 Tick cam.

 

Thats not bad at all, what compression? what did it run on whatever boost you had it set at and what rpms were you shifting at?

 

It broke a wrist pin before I got it to the track. I'm putting them on an ls3 with TFS 255 heads now. I was surprised that they felt stronger and spooled faster than the s467 Borgs I had on it before. One of the 67 Borgs broke a turbine shaft on 40 lbs. and my friend had bought them for a 5.3 and replaced them with 76/68s so I thought what the hell.
The Borg Warners would make 6 lbs. at 4000 in 3.5 seconds, I bolted on the 78/75s with no other changes and made 3 lbs. more boost a second sooner. The compression was 10.5. shifted at 7500-7800. Both pairs of turbos would go positive by 4000 from a roll on the street.
I had the Borg Warners on a 427 sbc that was 9.5 to 1 and they lit off right now once you were at threshold. Neither set spool like a light switch but they pull like a freight train when they light. I would guess that you would be very happy with them. My car is a driver with a heavy air to water setup, stereo system, bench seat, 32 gallon cell for range on E85 etc. that weighs 4200 plus race weight. So although I also run it a lot at the track, I haven't focused on short times. It ran a 9.33 at 155, but I think it will run better with the 78/75s if how it felt on the street is any indicator.

 

I'm only at 9:1cr, i've basically narrowed my choices down to the s366s whether cast or billet wheels or the vsracing billet 78/75s...at $550 a piece, dont think i can go wrong. Some guys say the billet wheel s366 is not really worth the extra $$ over the cast version. Another factor is my home track is in Denver at 5480ft elevation and the turbos have to work a little harder up here in this thin air so going a bit bigger on the turbos couldnt hurt. The car is 3435lbs with me in it, power everything except the seats, 8pt cage etc.

 

It’s hard to beat a pair of 366s.

 

Seen this ,don't know if yah ever ,been here before , but hope this helps yah in sum way ., #ad