burn4005

You have to use much lighter return springs on the itb shafts too.

yea listen through exhaust, listen through plenum and listen through oil filler hole.

What cams is the motor running? Compression is on the lower end of acceptable but cams can make a big difference.

Full race guys seem to have an inside line on the EFRs

yea they would be, but if you want a more agressive cam ramp they won't do the job. duration and lift doesn't tell the full story about cam design. there is another metric of the cam that is the average lift over the duration that tells more of the story about the cam profile. also, worth noting the Tomei cams quote the lobe height and kelford quote the net lift. so they're both a 10.8mm lobe cam.

Let's rephrase that to more development in the last 15 years. Tomei are of the vintage of t51 and t04e turbos and old heavy dual valve springs . The world has moved on and cars are now running ethanol, single beehives and extremely efficient turbos. I'm not saying kelford has changed the game but things like the split lobe 274s would likely suit the modern engine better.

That's strange. The catelog quotes the same inducer/exducer measurements so I'd be very interested in why the map is different and off the wheel or housing is different. I had assume it was the same for 9274 and 9280 without checking.

you won't have the same midrange punch. the 8374 will be much snappier as spool range on a 2.6-2.8l engine is in a higher efficiency area, and every % increase in efficiency here compounds the spooling effect.

if you're only chasing 550awkw, on paper the 9174 looks to be a better fit, but you do buy a bit of surge margin with the 8474 over it. How the rotational inertia of the ligher compressor of the 8474 helps for transient response vs the 9174 we'll see i guess. the new releases are really top-end power turbos but the midrange performance will suffer a bit.

as promised, here are the efficiency curves at pressure ratios of 3.0 (29psi)

I'm sitting on a plane after a 4am start looking at these on my phone so your probably right. I'll plot out the efficiencies at various PRs when I get some downtime to see what's what.

I'm a bit disappointed with the 8474 to be honest. The loss of compressor efficiency to increase the flow potential at the same exducer size seems to be a poor trade-off. It'll be more responsive than the 9174 with a more forgiving surge margin but worse at everything else. I think I would have rather have seen an 87mm compressor sized between the 83 and 91 that was better optimised to fill the 850-900hp power target, but there is no denying the 8474 will have a pretty crazy to end its still pulling like a train when the 83 compressor has fallen o. It's face.. The switch over in efficiency vs the 8374 happens at about 60lb/min at 2bar. I guess we'll see when they start getting into the wild. Here is the link to the new catalog. https://cdn.borgwarner.com/docs/default-source/default-document-library/bwts_performanceturbosgeneral_1892_2130.pdf?sfvrsn=3098b63c_2

I thought the new turbos had larger inducer diameters to increase flow (92 compressor is 73.7/91 instead of 67.8/91 for the 91. wouldn't that increase the trim from 55 to 65 and push the map to the right? or is the 9274 a different compressor again? because otherwise that is going to be more likely to surge not less. will hold judgement until I see a final product catalog with the comp maps and specs on it.

the press release says the 2019 turbo catalog has been published, but I can't find it anywhere.. still the 2018 one on the BW site. https://www.borgwarner.com/newsroom/press-releases/2018/10/24/borgwarner-releases-new-high-performance-turbochargers-catalog

Also what the hell is a 9274 going to be useful on? That is going to be rediculous comp flow for such a turbine.

Full race Geoff I'll take one 8474 supercore thanks

There is a reason all the new tech compressors come with anti surge housings and it isn't for looks.

You'd be pretty game to be making a main cap out of a dissimilar metal to the block. I'd expect there would be issues/fretting due to thermal expansion coefficients?

is the integrated main cap version made from Steel or are they all Aluminium?

I'd like to test that theory about turbine flow, Geoff could I place a standing order for an 8474 supercore [emoji4]

E85 is f**king gold. Even if you don't use it to its potential timing wise it is great engine insurance. Egts are low, it won't knock, engine is super clean. Happy days

My take is Higher compression engines are: -more thermally efficient, less heat out the exhaust (lower EGTs) which spools the turbo slightly slower. BSFC improves. -better off boost due to torque improvements -won't eat as much boost (dynamic compression) as low compression engines do. on a large engine with a small turbo (8374 on a 3.2 is a small turbo in my mind) it makes sense as you won't get much boost into the motor anyway before you overspeed the thing. I just hit the speed limit of an 8374 on a 2.6 at 8000rpm and 27psi at 490kw. so a 3.2 with the same VE% at around 6300 rpm you'll have the same boost limit. if you rev any higher you'll either have to taper it off, or run less boost, as the torque produced is really going to work your gearbox. its hard to know where the 1.05a/r housings limit is, as we were stonewalling the compressor and had a compressor speed limiting function in the ECU, adding boost wasn't really making any more power as the ECU was just pulling the target down anyway. it would be interesting to throw a 9174 core in there to see what happens with the 1.05 as it would be running near peak efficiency where this one is falling off. I wish I had an EMAP sensor, but the wastegate duty was quite telling. at about 7000rpm and up we had to really start ramping the duty in to maintain boost target, whereas below this point it was pretty flat. compressor efficiency was really starting to dive up here so to maintain shaft power by increasing exhaust expansion ratio it looked like this: (I'm using a 4 port 12w MAC valve and a 7psi spring in the gate, also using solenoid deadtime function in the emtron so real duty is about 12% more) running the thing on E85 also makes the decision much easier.

Probably need more crank prime at warmer areas

and for shits and giggles, here is the 91mm compressor. looks like a damn good fit too if you're heading for more boost.

here is my dyno log over the 8374 compressor map. the 8374 is a pretty good match for an rb26. I've moved the air flow scale slightly to make the turbo speed lines line up better. I would also expect the pressure ratio to be slightly higher due to air filter and intercooler pressure drop. I'm just using MAP here. you can see why they snap on so hard, it goes right through the peak efficiency zone when it's spooling.