R32 TT

Yep - I have had three different EFR's - and still run an 8474. All have had this casting issue and I didn't like it either. The Turbo's perform well - but its disappointing to see this lack of quality control - and yes it does make you naturally wonder if there are other problems that you can't see. I think that Borg Warners attitude to "its fine, and doesn't stop it working" is not a good thing. As others above have said, other manufacturers seem to get their castings nice and tidy and you would expect that the top of their line be well finished. Maybe BW should have a read of this thread and think about it for Version 2.0. PS. I've had 8374 and 8474 back to back on same engine - and I can say that in my experience the 8474 definitely does not spool as quickly as the 8374. I can say this from dyno charts, seat of the pants feel, logging and track times. The 8474 does exactly what you would expect: Spools a bit later (200-300rpm), and makes a bit more power up top.

so that's what - 4 days you've driven it?

6466 is tempting with the 5 Speed.

Yes all good - the only way for me to know is swap to a GTX3582 or 6466, perhaps 6870 to compare. A fair bit of money just to experiment though, and then - will I miss how it drives...? that said the 8474 is noticeably lazy compared to the 8374 for just an inducer change. Its not the "same down low but more up top" the internet seems to suggest.

Yep - following. Well then I guess the map has to be wrong - or I am making close to 900 engine hp. Which I doubt.

Sorry what I meant was, in answer to this question - "Do you reckon you're making the power you'd expect when your compressor speed and boost level suggest you are pushing at least 90lb/min of air?" - I'd say 'I think so', given the restriction to overall flow caused by eMAP. Would that be correct? Or am I misunderstanding?

I haven't looked at it on the map - but even if the compressor is making 90lbs on the map - there is that 1.2:1 back pressure no? Hence flow would be less?

Interesting that everyone is saying back pressure is a thing - I assume that is only once you starting pressing out 900+hp? Here is my 8474 using 1.05A/R on 3.2L Nitto. about 750hp at hubs. eMAP/MAP is rarely over 1.2:1 as you can see here 1.17:1 @7515rpm Yes circuit car, not Drag car - but I guess I this would be around 800-820hp at the engine - at what point does exahsut pressure become a problem - ? Or do you think I already have a problem...?

But.. the 8474 will be faster at a flowing circuit..

100% agree with above. And from practical experience I am 1.5-2secs slower on a Rally Sprint over a 150sec lap when using a 8474 vs 8374. There are times in 2nd gear I am below 4000rpm and that’s where the smaller turbo picks up time even though I have less power and top end speed.

Its seem silly to buy from Australia in any case. They are made in US. Why pay for freght to Australia, and then freight back to you. I would get straight from US. Try Geoff at Fullrace.com he has been very helpful to me and should be able to get you one. It may even get through customs a little more easily if he has sent to Bulgaria before and they've already gone through the steps.

Matchbot will tell you there is no way an 8374 should be on a 3.0L RB. That said, I ran mine happily for some years at sub 120krpm making 650-700hp at hubs and spinning to 7000-7500rpm on both 3.0 and now Nitto 3.2. Intake temps were ok - but it didn't want to make any more power. It has finally let go just two weekends ago. We had recently added launch control which may or may not have contributed (or at least shortened its life). Everything on Matchbot says its should be overspeeding, but I've got logs to show it wasn't (unless there is an issue with what/how we are reading) - so I am not sure how this correlates to Matchbot.. perhaps the default VE figures are different enough to affect it? I've also run an 8474 on same engine (3.2L, both 1.05 rear) and it definitely feels laggier than the 8374. On a dyno plot its only about 200rpm later coming on, but in practice, on a rally sprint coming off 2nd gear corners, you notice the difference. Also between gear transient response is dulled a bit. 8474 makes about 50hp at the hubs more on same boost (750hp at 23-26psi) , temps post turbo (pre intercooler) are only 10 degree cooler. And post cooler can't see a difference. Definitely when in the mid-range revs and up you feel the extra legs it has. So! for me, on a 3.0-3.2L I'd be going 8474 and altering gearing to suit what you're doing, and keep it a bit further up the rev range.

I agree.. based on my own car that would be boost in at around 4100rpm I think. But why they don't use RPM is beyond me.

Surely the bigger number is the 9180... (but yes, that could be wrong). I bet the 8474 must be different to drive though.

Will definitely be interested in watching this.. Don't like to add more complexity if I can avoid it, but seems like a simpler option to VCAM.