Another Truck?! Third Time's the Charm TURBOCHARGED

Yeah I just went through this with the diesel. Never heard the turbo before and now with no muffler you can hear it at idle and low rpm too in very nice, and I'm sure you're right that the smaller turbo will be a little spun up at idle vs a big one. Sadly no woosh sounds for me. You're definitely more mature than Monte and I, we both want to hear turbo noises at all times

 

You guys would love Jayson's 91 pickup with the turbo 3RZ in it then, we put a double ball bearing PSR 3071 on it, thing is always making noise and it has what is essentially the HKS T51R mod done to the compressor housing so when it spools it sounds like the turbo noises from every videogame of our childhoods. That said... I prefer mine that isn't making noise unless I'm trying to accelerate, his is always making noise even just cruising on the highway.

I think a lot of people's 5VZ turbo builds make that kind of noise too because they're putting too small of a turbo on, the 3071 and 3076 choke these engine out up top, can just watch the power roll off on the dyno. Even my Garret 60-1 is a hair small in retrospect, but the next most ideal turbo for this engine is about $2700... so probably not doing that just yet.

 

Turbine housing selection will have a lot to do with where you spool up and similarly when you choke out... a .72A/R vs a 1.21A/R will make a big difference in where the power is, even with he same compressor!

 

Yes and no, the .63/.82/1.02 housings on the 3076 all spool up within 200rpm of each other on the 5VZ, and even the 1.02 chokes at the top end, it's just too small of an exhaust side for this engine no matter what trim housing you run. Spooling up super low but not flowing enough doesn't make usable power, it makes pressure. All the housings spooling within a close range is also a hint that the overall turbine size is just too small. You'd be correct about the housings playing a bigger role in tuning response and managing torque peak if the turbo was more appropriately sized to begin with.

 

Yes if I ever get around to turboing the SX. T51r mod will be happening. But it's also a daily driver and I rarely drive it longer than 30 min a go. So noises in that will be fun.

3076 seems tiny for a V6. Maybe twins..

 

Yeah it's crazy, it's the first couple choices in the CX kit options and ask any of the FB morons and they'll recommend it too (but most of them are scabbing together some stock ecu modified FPR nonsense anyway and probably will never visit a dyno) haha. I want one of the new Garret G30 MKII turbos, they're so crazy efficient now that one the same size as my 60-1 spools 10% earlier and can handle 25% more flow.

 

yeah trying to have a higher mass flow rate at lower pressure ratios (~2.0) its the compressor side that can't keep up and you run into shaft RPM issues, usually twins needed for the best of both worlds haha.

But with a 5VZ without cams/intake mani I'm not confident its the turbo (even a 3076) causing significant power drop off at the higher RPM I guess, as just an educated observer, craming much more than 50 lb/min is not really possible without simply going to higher boost levels.

and Just being able to stuff more air in there with a higher flowing turbo won't suddenly let you make peak power at 6500 rpm is all I'm getting at really.

 

My dyno graph vs any with a 3076 says otherwise, of course other things to maximize efficiency like the intake and cams (especially timing them) would help but you actually choke the exhaust out pretty easily with such a small turbocharger is my point here. With Jayson tuning so many of these 5VZ setups a week now I get to see the VE maps showing that efficiency drop at the top end on the builds with 3076s. I understand what you're saying too though, I'm not so much talking about massively shifting the peak power up so high (you'll absolutely need mechanical mods to the intake and timing for that), I'm saying it is rolling off just barely after the stock peak with these small turbos. Whereas I can pull nearly to 5k and then hold steady for a bit before dropping (mine is still a bit too small). You can even try to prop up the 3076 builds with more boost at the top to attempt to keep torque linear and its a losing battle, just makes a ton more heat because of the back pressure.

 

it may be completely semantics, and especially since I've elected to drop the 5VZ entirely... but you are indicating that the compressor side is the issue?

and that perfectly matches the assertion that "turbo too small" lol

a 3076 will only flow ~56ish lb/min, and a 3071 about ~52ish lb/min; and your T60-1 will flow as much as 60lb-min, so you may have some A/R or Exhaust tuning to possibly do (or just up the boost a little and max that turbo out), but anyone on a smaller turbo is just out of flow on the compressor side, no matter how free-flowing the exhaust is... no amount of mod will make more power up top except another turbo.

 

It's an exhaust turbine cross section size issue, it cannot flow enough exhaust, it is a restriction. At low boost it is fine, but back pressure actually begins to restrict the gains starting as low as 10psi on the 3076. I don't think the compressor side is entirely out of its range though you'd be pushing it out of its efficient zone for sure (why do that if you could run a larger compressor and save yourself the heat) but putting a larger turbine side on the that same CHRA and compressor would make this not a 3076 by definition, so I wasn't about to argue hybrids here that's why I advocate for a larger turbo so you can stay in the more efficient range of the map. I'm not saying slap a Holset HX35 or a Borg Warner S475 on or anything extreme, just try to shoot for middle of the map in the range your engine works in. Turbo sizing is a dark art and I've learned some people shoot too small citing "muh quick spool" and some shoot too big citing "big gains brah" but it's really hard to cut perfectly to total usable range for a given engine and its configuration. I've just seen enough of this same turbo people are using and it can't even make the same power as mine at the same boost, you can tell when fuel starts to taper off in the VE map that it's just failing to flow. But open up the exhaust and they'll keep making power without cranking up the boost in response to fall off. Again this isn't denying that mechanical modifications to heads and cams could make even more power at less boost on either setup. I'm at a point where I don't feel like it would be wise to turn mine up more really, maxing this turbo out would be enough to blow this engine if I just cranked the boost in response to torque fall off. Right now I'm happy I can maintain my boost to redline fairly easily.

 

I'd argue its only a dark art when you do start modifying the turbo, either clipping wheels or making hybrid setups, before that it really is pretty straightforward math, but a lot of math unless you make assumptions and focus just on the main changes and impact from compressor/turbine choices, as well as the RPM and boost levels you are trying to run...
but I agree with everything you've said, and I don't even know the scale of the fall off we are arguing over lol. Just enjoying a discussion on turbocharger sizing as I gear up for my next MR2 motor (2gr turbo) the larger A/R I referred to earlier is the same as improving flow thru the turbo, I'd differentiate flow thru turbine housing and "exhaust" flow however, a good external wastegate can ensure the turbine size isn't a problem, its the compressor moving outside of its efficiency range and hitting the max RPM range the turbo is rated for leading to a falloff in power at the same boost , and as you said, simply not being able to flow any more.

 

It's not so much a dark art because the turbo information is untrustworthy. It's more because the engine variables are usually non-existent or untrustworthy haha. @2RZNoShi1 has a better intuition for sizing them than I do. But I'm interested to see what you decide to put on the 2GR, it's much more efficient in the 5VZ, certainly don't want to choke it

 

Talking about compressor vs turbine flow and efficiency, absolutely none of these 5vz's are even coming close to maxing out the compressor wheel. 100% of the problem is turbine wheel. It doesn't matter what turbine housing you put on a 3076, at the end of the day, the turbine wheel is still a 60/55. So at a certain point you are giving up spool while also hurting your top end potential. My opinion on 5vz turbo sizing has and always will be that the 3576 is the correct size turbo, likely with a .82ar housing, because it's a balance of spool and flow for a 3.4L engine. If you directly compare a 3076 and a 3576, the only difference is the turbine wheel. 3076 is a 60/55 and the 3576 is a 68/62. Compressor side is identical. I try to remind people when selecting a turbo, that Garrett wouldn't have made the same turbo with different turbine wheels if one could be used efficiently on anything. And I think people don't understand that a turbo that provides full boost at 2500 rpm but falls completely out of its efficiency range at 3800rpm will not provide nearly as much benefit as a turbo that makes full boost at 3500rpm and will hold in its efficiency range until 5k or so. At 2500 rpm, all you are doing is creating very high cylinder pressure and a lot of force on a piston that is moving relatively slow. I genuinely believe that back to back on a dyno, all things the same, a 3076 with a .82 and a 3576 with a .82 won't differ THAT much in spool, but the difference between the torque lines above 3500 rpm would be staggering. Zane's 60-1 turbo has a turbine wheel that is a 72/63 stage 5 wheel, and it's pretty old inefficient tech, and on the dyno it still makes 16psi at 3600rpm, and if you put your foot down at 2200rpm it will make 10+psi by 2600-2700. It's just not really usable there.

 

I understand what you are saying, it makes sense; and I see that the completely different compressor maps out there between the 3076 and the 3576 with the same compressor wheel and compressor housing are purely driven by that change in turbine response.

I have a lot of turbo experience, but none with Garrett and how they name or spec stuff, so I've been basing everything on available maps... and I definitely see the massive increase in turbine flow available in the same A/R between the two, and now see they also spec the same compressor wheel and housing between the two, and it definitely clarifies I was on the wrong side of the shaft lol

aand agree with the suggestion for how to spec in middle of power band to match compressor efficiency.

Do you have any suggestions on a Turbo for a 3.5L revving to 7500 RPM looking to make ~600 wheel?

 

If budget is less the concern, a g35-900 would be friggin sweet on that thing. A .83ar housing or 1.01, pending where you want your power. 2gr has a lot of advantages like vvt to get more response AND more flow. I see supras make 30psi at about 5k rpm on that turbo with the 1.01 housing, and it will flow enough to make 850whp. With more displacement and higher compression, I wouldn't be surprised if you were able to make 20-25psi at around 4200-4500rpm with the 1.01, especially on e85 with the right timing for spool. It maintains an almost perfectly flat torque curve from peak boost all the way up to 7500rpm, which would give an absolutely killer setup. The .83 may be a touch small, but would bring your torque down, with some fall off up top. If you are wanting to swing budget side, a pulsar 6466 with their .96ar housing would be a badass setup. Especially if you are making the manifold, or can modify it to run the dual v band .96 housing. It should also do around 900 crank HP at the high end and be sized about right for a 3.5L

 

If I had Facebook I'd feel personally attacked by this comment. That being said I still want to get my truck over there for a dyno day and let @2RZNoShi1 see his tune in person.

 

Hooray rectangles!

 

Also I discovered the reason my truck had been clunking on off camber terrain changes was not because of the creeper joints in the rear but in fact because I had only one bed bolt that was tight

 

Yay! Back on topic from all this turbo talk.

 

Distractions abound, but we gotta at least get the flatbed portion of this project done before switching projects again.