In general, I think that this turbo has a mismatch between the compressor and turbine wheels. The more efficient an engine is, the more the restriction in the exhaust will be evident. In contrast, a less efficient engine is going to need more pressure on the inlet to get the same mass flow out the exhaust, so it might be a better match. That....or a smaller engine period. (This probably why the Ford Focus with it's smaller engine was able to do so well with the GTX3076R)
Then there's my engine, which is absolutely stunning me with how efficient it's airflow is. It was sucking air through the compressor faster than the turbine wheel could let it out....at all RPMs. The GTX40 feels stronger off-boost in comparison to the GTX30.
Considering my experience with the GTX30, one might expect that I could recommend it for XXX HP on our engines....but I can't. I think it might be a good turbo for a lower efficiency 2.0 - 2.5L engine, but with higher airflow it's not a good fit. On my engine, at about 42 Lb/min of airflow, the exhaust back pressure starts to exceed the inlet manifold pressure. If I target 19 PSI of manifold pressure, this happens at approximately 4000 RPM. If I target 10.5 PSI of manifold pressure, this happens at a higher RPM. If you want to run more than 42 lb/min of airflow, at any RPM, a different turbo would be a better choice. As odd as it sounds, I think the GTX3071 would have been a better fit for my engine, it just wouldn't make as much peak power. The cost of using the GTX3076R is high EBP....and you either add high octane fuel to deal with that, or lower the boost. The GTX3076R is probably fine up to 400whp, but it's not the best fit for how our engines operate.
For those wondering about my comment on high octane fuel: High EBP means more of the exhaust charge is left in the cylinder during the intake stroke. In-cylinder charge temps end up being higher, and you need higher octane to combat that.
I wonder what the backpressure is for an N55 motor on which the owner has cranked up the boost — 3.0L and an even smaller turbo. Maybe past 2:1?
I've not heard one person "like" a GTX3076R. The GT3076R was a big mismatch between compressor and the small 60 mm major dia UHP turbine wheel (which is REALLY old tech). Then they put a higher flowing turbine wheel that takes more torque to spin at any RPM, and saddle it with the same turbine wheel? No shocker that the turbine inlet pressure required to drive the thing was through the roof.
I believe I mentioned it when you were thinking about using the GTX3076R - the GTX3576R is a much better fit, and will make more power, and typically have a faster response as the larger turbine wheel can provide more torque at lower massflow conditions that the big compressor wheel needs. I think you're seeing that with the GTX40.
FWIW, the GTX3076R having good boost control is the same as sticking a silencer plate in your exhaust with the GTX40 - you had really high EBP, and that compensated for the poor WG flow priority on the manifold. Take away that high EBP condition - and you're only going to get creep.
Maybe you are confusing me with someone else?
I don't recall telling anyone on Bfc that I bought a GTX3076R until months after I took delivery of it. (I ordered the GTX3076R in November of 2011, and this thread was started in November 2014.)
Or perhaps you are referring to when I was considering running a TS housing on the GTX30 with the Steed Speed? There was certainly a lot of suggestions at that point....and I remember you being quite helpful along with Phil and Butters.
Maybe it was after you already had it - but yes, the GT35 turbine is a much better fit for that much compressor wheel.
This is the basis of my issue w/ boost creep. Went and put my 7675 on with a 4" exhaust right off the turbine housing (.81 AR open T4) for maximum horsepressures and found that my EBP is the opposite effect of what Adam saw w/ the 3076 - there isn't much motivation for exhaust to change direction and leave the collector area pre-turbine despite the dual 44mm holes I poked. It's better now, but still not perfect. I think coercing it with some scavenging by recirculating the WG's may work, but that's a PITA.
I know you don't want to fab up a new exhaust, but do you think switching to 3.5" would provide a little backpressure to increase boost control without having a significan impact on horsetorques?
Its usually said that you can't get too big with a turbo exhaust dismeter. Thats mostly in literature from the 80s/90s. I wonder if a "huge exhaust" then was like 3" diameter? Kind of like the statements that you want a really small cam with a turbo engine. It worked at the time because people used really poor flowing manifolds and inefficient turbos.
Adam, what is the diameter of your exhaust again?
3.5 wouldn't be enough reduction. 3.5 will flow a shit ton of power w/o choking at all.
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3"
At the time I did it I wasn't thinking primarily about power, it was about noise. 3" is quieter than 4" in general, and that was...and still is important to me.
The thing is, my exhaust is 3" straight through.....you can roll a tennis ball from the turbine housing out the back through all 3 mufflers in place.
Since I have the sensors and data channels, I might add a bung on the exhaust just after the WG recirculation to measure exhaust pressure at that point. I'm very interested to see how far I can stretch the use of this exhaust before it's an issue....
I am considering removing the oil cooler from my engine.
Under most operating conditions, I don't see engine oil temps going over 200 degrees, Realistically, I should be running the oil over 210 degrees to help vaporize moisture contamination, but I very rarely see that kind of temperature. In fact, most of the time I don't see over 190 degrees on the street!
Being that I have really good control of coolant temps....able to hold them under 200 degrees at the drag strip hot lapping....and under 180 on the street....I think I might have over-done my cooling package.
Can you add a thermostat for the oil temp?
Capital Driving Club Car # 102
How to turbo your car:
Step one. Install ecu and learn to tune and or have it tuned.
Step two. Install injectors and retune.
Step three. Install turbo parts and bits. get it running with out leaks. DO NOT DRIVE IT. Idling should be ok
Step four. Retune car
Step five enjoy
What about a small oil to coolant heat exchanger like a lot of OEM cars have (primarily Japanese, but you can get aftermarket ones)?
You'd get faster oil heating, and still be able to control excessive oil temps if they start to get really hot for some reason. Advantage of also not needing to duct another heat exchanger, and the mass impact is very low.
I've had oil temps way high in my car but like 99% people say, no track use, it's not required. Try hot lapping for 30 minutes straight with a turbod M5x / S5x and you'll want a cooler just because of the noise it makes. Thermostats should be used on aftermarket setups, they are cheap enough. On top od that the turbo is only oil cooled so take that into consideration.
Good data point. Thanks!
Yes, but it comes with some compromise...mainly the complexity of adding 4 additional connecting points to the oil system.
I was originally planning to use a Laminova oil cooler. However because of how much the OEM cooling system would have to be modified to accommodate this, I went with what I thought was a "simpler" system.
The one thing that needs to kept in mind is that the oil pressure regulation is based on a feedback circuit from the main oil gallery in the block. You can add all kinds of stuff after the oil pump, and the regulation valve will accommodate this up until the pump runs out of capacity. Adding a thermostat that in theory might affect flow, will be compensated for by the oil pump. Want to put 3 oil coolers in series? The regulation valve will compensate for the pressure drop through the cores. A thermostat is a viable option.
Of course....running a dry sump would also change things...
S54 housing has a thermostat for the cooler. It’s what most use.
Adam - I really like the N20B20 oil coolers as fitted to our X1 M Sport. Small but effective.
While I was still supercharged, I swapped in the S54 filter housing and a 10AN adapter for the cooler ports and bought a nice 13 row cooler. Put the turbo on about 6 months later and found my oil temps ran cooler with the water and oil cooled turbo than the oil cooled Vortech V2 and that I did not need a cooler. That was 8 years ago and my cooler ports are still capped. But I am not trying to make 1000 rwhp and do not track my car and live in NH where temps don’t get over 100F.
At what whp/wtq do you expect the Timeserts to start to pull out of the aluminum block?
'97 M3, Estoril blue, 2 dr, euro 6-spd, EFR 9180 divided T4 .92 IWG, RK tuning, CP 8.5:1 pistons, Eagle rods, Schrick cams, L19 11 mm ARP studs, O-ringed block, Supertech stainless/inconel valves, Supertech springs & Ti retainers, ported head, S54 oil pump/pan, 80 lb. injectors, OBD1 intake manifold, Steedspeed twin scroll T4, 3.5" SS exhaust, eBoost2 EBC, HFS-4 W/M injection, AEM Failsafe, Zeitronix data logger, Racelogic TC, OpenOBC w. ethanol %, Ireland Eng. engine mounts, UUC black tranny mounts w. enforcers, UUC twin disc feramic, ARC-8's, MCS 2-ways, Z3 rack, Rallyroad strut bar, X brace, Eibach sway bars, Ground Control LCAB bushings, Bimmerworld RTAB's, Powerflex subframe bushings, 210 4-clutch LSD, Stoptech BBK, titainium shims, steel braided lines, brake cooling ducts.
He will let us know later this year.
I don't have any indication that this will be a problem.
800rwhp was made in Sweden with 10mm head studs without timeserts.
I'm running 11mm studs and timeserts....so the thread engagement into the aluminum is closer in surface area to 1/2" stud.
If the aluminum anneals, that would be a problem regardless of the size of the fastener, but so far I haven't put that kind of heat into the block.
Since this is primarily about cylinder pressure, as long as I keep the torque to a manageable level I should be OK. My goal is to manage torque output with boost and timing to keep the curve flat from about 5000 - 8000 RPM.
To give an idea of the strategy:
First Gear = < 200rwtq
Second Gear = 300rwtq
Third Gear = 450rwtq
Fourth Gear = 600rwtq
Fifth Gear = < 750rwtq...but realistically I'll probably top out around 660 with nitrous.
The target is not so much engine torque, as axle torque after transmission and differential multiplication. Somewhere around 2600 ft/lb on street tires with a good road seems to be my current limit. If the head studs pull out of the block, I'll just mark that point in the data, and set the limit under that for the next block. (I have a spare block)
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