Garrett G Series

[waxracing]

26 minutes ago, Duncan said:

that is a very interesting manifold design. 

I know you've got it so you want to use it, but you should also consider selling it to someone who wants genuine, period correct parts for a gazillion dollars and then buy something more modern and top mounted that has more space for a turbo and a more efficient design

Maybe I am that guy that wants those parts. 600 hp at the engine will give me about 500 whp or 370kw. I’m ok with that.  This is a toy car for the weekends playing in the mountains.  I don’t want a highway drag car at the expense of response, I have other cars for that.  But thanks for your thoughts 

[Dose Pipe Sutututu]

One thing to note, fitting a decent sized turbo with that manifold will require you to trim part of the engine mount area.

I believe @WARLORDdid this a decade or so ago, maybe closer to 2x? Lol.

[GTSBoy]

26 minutes ago, waxracing said:

600 hp at the engine will give me about 500 whp or 370kw.

Yeah nah. I typically discount roller dyno numbers, particularly for powerful RWDs by 25%. 600 engine HP will usually turn up as significantly less than 500 wHP.

There's a lot of problem these days with hub dyno numbers becoming more common, making people think that the gap between chassis dyno and engine dyno numbers is smaller than it is - because it is smaller with hub dynos. The loss at the tyre-roller interface is removed, and it can be very large, and it is also very variable, depending on the tyres, the condition of the rollers, the way the car is strapped down and the amount of power being transmitted.

[waxracing]

14 minutes ago, GTSBoy said:

Yeah nah. I typically discount roller dyno numbers, particularly for powerful RWDs by 25%. 600 engine HP will usually turn up as significantly less than 500 wHP.

There's a lot of problem these days with hub dyno numbers becoming more common, making people think that the gap between chassis dyno and engine dyno numbers is smaller than it is - because it is smaller with hub dynos. The loss at the tyre-roller interface is removed, and it can be very large, and it is also very variable, depending on the tyres, the condition of the rollers, the way the car is strapped down and the amount of power being transmitted.

Maybe I only make 450 hp then. Im not trying to build a dyno racer. 

[soviet_merlin]

1 hour ago, Duncan said:

just to add....keep in mind "600hp" is about 300kw at the wheels, which is not a lot these days (every second gtst seems to be making 1,127hp).

Hang on, do you have a typo in there? 300kw is 400hp. I would think that even with AWD that's nowhere near 600hp at the engine. You are going to make me think I'm driving an almost 600hp car which I'm pretty confident I'm not. Not even on the internet

600hp is another step up.

(Not disagreeing with the gist of your comment though)

[GTSBoy]

5 minutes ago, soviet_merlin said:

Hang on, do you have a typo in there? 300kw is 400hp. I would think that even with AWD that's nowhere near 600hp at the engine. You are going to make me think I'm driving an almost 600hp car which I'm pretty confident I'm not. Not even on the internet

600hp is another step up.

(Not disagreeing with the gist of your comment though)

That's why he has quote marks around the 600 HP. If someone has 570, they will round that up to 600. And 320kW is barely more than 300, so easily meets the description of "about 300 kW. And if you use a 25% discount for a roller dyno, those numbers are the same thing.

[waxracing]

43 minutes ago, GTSBoy said:

That's why he has quote marks around the 600 HP. If someone has 570, they will round that up to 600. And 320kW is barely more than 300, so easily meets the description of "about 300 kW. And if you use a 25% discount for a roller dyno, those numbers are the same thing.

Damn I have another vehicle that does 348 at the wheels and I never say it’s 350. I just tell the truth 

[Butters]

19 hours ago, mr_rbman said:

I know a guy running a G35-900 (0.84) rear on a standard stroke RB26 and he's having issues too...

RB's love big exhaust sides, I'd personally go the 1.01 rear at a minimum if it were me...

You'll see a heap of examples on this site alone where guys have kept the same turbo but gone up a size in the rear and lost virtually no response...

On G series ?  or more in general , any back to back dyno sheets kicking around ?

[r32-25t]

It’s well known rb engines like big rears 

[Butters]

1 hour ago, r32-25t said:

It’s well known rb engines like big rears 

I hear this a lot, specially from motivedvd but rarely see any data.

It's also not usually all gains , some trade off is at play.   So its about getting a setup fit for your purpose.

I've had really good success with smaller .8 rears on RB26's, always wondered about going larger but a back to back test is very expensive.  Be great to see some data to sway the expense. I'm not in the 1000hp plus region where i suspect larger rear is always going to be better.

 

[GTSBoy]

My opinion on big rears?

They gotta be the right size.

[r32-25t]

23 minutes ago, Butters said:

I hear this a lot, specially from motivedvd but rarely see any data.

It's also not usually all gains , some trade off is at play.   So its about getting a setup fit for your purpose.

I've had really good success with smaller .8 rears on RB26's, always wondered about going larger but a back to back test is very expensive.  Be great to see some data to sway the expense. I'm not in the 1000hp plus region where i suspect larger rear is always going to be better.

 

I have a friend on here who had a 2.8 with an efr 8374 with a 1.0 rear on it, the emap was rising fairly a lot and the turbo speed had been reached, with that setup it made 485kw the wheels. He then swapped the rear out for a 1.45, the emap went down, the power went to near 520kw and had zero noticeable extra lag 

[r32-25t]

E85 increases exhaust gas volume and then combine that with an engine that revs to 8,000+, makes 5,6,700hp at the wheels and your going to be moving at lot of air out of the engine which needs some where to go 

[Mick_o]

21 hours ago, r32-25t said:

I have a friend on here who had a 2.8 with an efr 8374 with a 1.0 rear on it, the emap was rising fairly a lot and the turbo speed had been reached, with that setup it made 485kw the wheels. He then swapped the rear out for a 1.45, the emap went down, the power went to near 520kw and had zero noticeable extra lag 

 

[Lithium]

On 10/02/2023 at 4:12 PM, Butters said:

I hear this a lot, specially from motivedvd but rarely see any data.

It's also not usually all gains , some trade off is at play.   So its about getting a setup fit for your purpose.

Motive DVD share a lot of good info, and try their best to interpret and explain data well but there are plenty of times out there where the same data can look different depending on what you know and what you are looking for.   Truth of the matter is here....

On 10/02/2023 at 4:24 PM, GTSBoy said:

My opinion on big rears?

They gotta be the right size.

This.  There is no "RBs like big rears".   RBs don't have a clue what is attached to their exhaust side, from the turbo's perspective its the dynamic of how fast the compressor needs to spin to pump the required air, intake manifold pressure required to achieve that and how efficient the compressor is at that point, and well the turbine/housing combo works at that point.   

Sometimes you need to go a bigger a/r to achieve what you're doing, whether it be that the whole setup works best there or sometimes just if you are pushing the turbo to the absolute limits and don't want to upgrade the rotating mass so going to a bigger a/r is a bandaid which is what imho has happened in a few situations that are used as evidence that "RBs like a big rear".   

I'm pretty confident that with everything else being equal that an EFR8474 with 1.05 hotside would be all around equal or better running at 520kw than the RB28 with the EFR8374 and 1.45a/r hotside in the example above.  If the compressor is being more efficient to move a given airmass than a different compressor on the same turbine without making the turbine work any harder to the work then the wastegate will end up not having to close as much to keep driving an out-of-it's-depth compressor to do something to the edge of it's limits.   It can take a pretty significant turbine wheel/housing upgrade to match the effects of boost control creating an exhaust leak that is required to hold back the compressor from pumping more air than is needed when comparing with something that probably effectively has the gate shut to achieve what it's doing.

To throw a bit of data into it, here's a 1.05 EFR8474 on a big cam 3litre being revved to 8000rpm on ethanol.  The car made over 600kw (/800hp) on this run, around 87lb/min of airflow which is WAY past what an EFR8374 can support - so while 39psi EMAP is getting up there a bit in this case (which is why it was stopped here).... the thing would be barely working up a sweat at 520kw on an RB28.

 

Edited February 11, 2023 by Lithium

[mr_rbman]

On 2/10/2023 at 11:47 AM, Butters said:

On G series ?  or more in general , any back to back dyno sheets kicking around ?

32zlrr on IG, he runs a G35-900 with the .83 rear, still makes over 500rwkws but the rear is definitely a restriction...

[32gts425det]

On 9/2/2023 at 10:41 AM, Lithium said:

So this is kinda relevant to this conversation, someone else have mentioned non-Garrett options so I feel like its not MILES from being appropriate to mention anyway as this suits the turbo matching concept and also possibly offers a housing option if you go genuine Garrett G35 900 core.

A mate with a GT-R which was running twin -5s on an RB26 with Kelford 272s had one of the turbos fail recently and it was going to be annoyingly hard work to replace when he already was aspiring to put an RB28 in it and go single turbo at some point, probably the likes of an EFR8474 when the budget allows but he was not ready to take it off the road.   Some big yarns were had about what would be the most rewarding way to get it running now but also not result in too much back tracking in the future.   The target was be at least as good as the -5s, fairly typical low mount twin setup with just over 500whp on 98 and full boost in the late 4000rpm range.

After much discussion around things like G30s, going straight to EFRs etc the budget right now wasn't suiting so partly to get it going sooner but also just to try something different he went with a Pulsar G35-900 copy with a .85a/r divided T4 housing.   Hoping it will be going in a couple of months or so with the divided housing, I can report on how that goes but I do realise people view the Pulsars as not at all a comparison with Garretts and the T4 hotside isn't even an option from Garrett, but I mention it partly because Pulsar *do* do a .85a/r T4 divided hotside which in theory should suit a G35, genuine or copy.

The Pulsar will at least be on there to get it running until an EFR/RB28 build can be sourced and delivered - though if the Pulsar performs too good it may stay in there longer haha.

I’d love to know the results of this mate, I’m thinking of going the same turbo on a built 25det, e85. 

[Butters]

Whilst being very happy with how my car drives and overall power number(g35-1050). The car wasn't responding to changes well(boost or timing) and I seemed to be tapped out at the low 700 range.  I did expect the turbo could make more given the results I have seen here and there, I am always keen to solve problems. I run the smaller housing(.83) , a 4 inch dump but a 3 inch exhaust. Whilst everyone was saying go the bigger turbo housing, I decided to change the exhaust given I didn't want to lose spool. I went all out and built a titanium 4inch from dump back.  Result was amazing as below and this is with 2 degrees less timing, on same timing it made 788.   It made more power everywhere. Fair to say i'd likely get the same result on a 3.5 inch but clearly the 3inch was holding it back.  Both my tuner and I thought it would go over 800 now with more boost. 

 

3 inch vs 4 inch - dump back 

And yes at measure point the boost is higher but that is not the case everywhere  

 

[hattori hanzo]

chuck a bigger rear housing on it as well and i feel you will gain more everywhere again particularly if on E85 

[Lithium]

On 11/04/2023 at 7:52 PM, Butters said:

Whilst being very happy with how my car drives and overall power number(g35-1050). The car wasn't responding to changes well(boost or timing) and I seemed to be tapped out at the low 700 range.  I did expect the turbo could make more given the results I have seen here and there, I am always keen to solve problems. I run the smaller housing(.83) , a 4 inch dump but a 3 inch exhaust. Whilst everyone was saying go the bigger turbo housing, I decided to change the exhaust given I didn't want to lose spool. I went all out and built a titanium 4inch from dump back.  Result was amazing as below and this is with 2 degrees less timing, on same timing it made 788.   It made more power everywhere. Fair to say i'd likely get the same result on a 3.5 inch but clearly the 3inch was holding it back.  Both my tuner and I thought it would go over 800 now with more boost. 

 

Nice work, congrats on the result and cheers for sharing - have been pretty sure that it should be able to make more even with that housing.   Looks like a nice fun delivery too, glad its making more the kind of power it should be now