Jump to content
SAU Community

Recommended Posts

Take into account the GT3076R pumps more air for the same rpm - ie needs ~104000rpm to push 25lb/min at 1.5bar of boost whereas a GT3071R needs ~112000rpm (9% more rpm required than something with 7% more inertia!?!) it stands to reason that in terms of transitional throttle a GT3076R might not be as bad as you'd expect.

It isn't that I'm scared of the 76 being bad, I just want it to be as good as possible, ultimately I'd love to see 280kw with the turbo on full song from 3-3.5k all the way to 7.5k, currently I can't find anything that does that. All the 76 graphs I see vary from 3700-4500 depending on tune and dyno settings. GT28 seems to come on about 3.5k but dives over by 7.5k and doesn't make 280kw unless you run E85 and really really lean on it.

Can anyone think of any turbo/gate/manifold combination that will achieve this?

The reason I want this combo is I want 4k of revs between when the turbo is on full boost and when torque starts to drop off. The only other way to achieve it is to build a motor that will spin to 8k+ everyday, then the gtx76 with external gate will give the same power band, just from 4k upwards. That or build a 30.

Edited by Rolls

its a good idea but I think the major problem is a turbo that is super responsive down low and still be able to have boost increased at top rpm. Most turbos that satisfy the response criteria mentioned above are normally maxxed out up top and no boost controller can increase boost if the turbo is maxxed out.

have you thought about a boost controller that has an rpm input? you could increase boost in the upper rpm range to keep power from decreasing.

If I could safely increase boost in the upper rpm I would also increase it in the midrange.

How does everyone think a twin scroll GT3071R would go on an rb25det with the appropriate power, would it come on much sooner than it already does? and if so what about peak power, would it be basically the same?

Would external gate vs internal make much difference? I'm trying to figure out what the ultimate combo for response and around 280kw would be.

You seem obviously in pursuit of the ultimate "response" combo. Is such early and I assume non progressive "response" really be that great to drive in 2 wheel drive? Aren't you just getting early "tail out" via traction loss. A common condition for me in my "responsive" via 4L F6 Ford. On topic I'm trying twin scroll, split manifold, twin gates, with VVT with stall converter to deal with lag in my gt35 based set up ATESSA in my gts4.

Edited by WHITE gtt

You seem obviously in pursuit of the ultimate "response" combo. Is such early and I assume non progressive "response" really be that great to drive in 2 wheel drive? Aren't you just getting early "tail out" via traction loss. A common condition for me in my "responsive" via 4L F6 Ford. On topic I'm trying twin scroll, split manifold, twin gates, with VVT with stall converter to deal with lag in my gt35 based set up ATESSA in my gts4.

For me yes it is great, it is the same reason people buy v8s for that low down massive torque, you are right it probably won't make it faster and might actually make it slower but that is what I want, the fattest biggest torque curve I can attain, but I also want it to hold the torque to redline. It is a street car and I love the brutal smack I get at 3k with my current highflow, however it starts to fall over by 6k, if I could get similar response with it holding to 7.5k, it would feel amazing.

So lithium you never answered, how much difference do you think there would be between the GT3071 and GT3076 in terms of boost, if all things are the same, GTX or GT, twin scroll or normal, how much spool am I going to gain from the GT3071, 100rpm, 500rpm?

I do realise all your points about the 76 making far more power on less boost, holding to higher revs etc, but I still would like to know, as if it is 500rpm, then even if I only make 280kw and having to lean on it very hard eg 20psi+ it is still worth it to me.

Edited by Rolls

You seem obviously in pursuit of the ultimate "response" combo. Is such early and I assume non progressive "response" really be that great to drive in 2 wheel drive? Aren't you just getting early "tail out" via traction loss. A common condition for me in my "responsive" via 4L F6 Ford. On topic I'm trying twin scroll, split manifold, twin gates, with VVT with stall converter to deal with lag in my gt35 based set up ATESSA in my gts4.

The key word here is non-progressive. Yes, I would agree that having a lot of low down torque and then it falling away would not be a great result. I believe Rolls is saying great response but progressive torque. The ultimate in my my mind would be flat torque from 3,000rpm to 7500rpm and a peak of 280rwkw on 98.

I have just changed this year from a big laggy turbo to nice super responsive turbo. I love it, I am able to quickly access torque through tight corners and feed the power in progressively when exiting the corner. The only negative is that over 100km/h driving has lost the pull feeling. For a fast street car it is ideal. But it would be great to have this progressive response and then keep pulling all the way to redline.

Regarding the GT35 on the 4L ford engine what rpm does it kick out? I have had a 3.8L engine with a GT35 and it was very taily when the turbo would hit. Is it not just a matter of housing choice? With the 1.06 housing it would hit hard, where as I tried a 0.63 housing and it came in much earlier but was more progressive so traction was not a problem. But the 0.63 fell over massively up top. I think its just a matter of matching the turbo to the engine and getting 'progressive' power delivery.

I think some of you people ask for the impossible at times . I highly doubt that a turbo exists that will make significant boost at 3000 revs and still do it at 7500 revs .

The problem is that automotive turbochargers use rotary non constant displacement compressors and their pumping abilities are not linear .

The car manufacturers go to some pretty extreme lengths at times to attempt to have a wide flat torque band but its not endless .

Some of the methods used are about making the engine have good cylinder trapping abilities which generally means some kind of variable valve (cam) timing and sometimes lift as well . In a perfect world we'd have actuators of some kind to give virtually infinite valve timing flexibility .

Take it to the grave , in the world of engineering RB engines are not exactly high tech things and the best of them can only move one cam without lift alterations and whilest ITBs are available they only bolt to RB26's .

None of them have twin scroll or VATN turbochargers and from a competition perspective parallel twin turbos are as good as it gets .

Gearing also has a lot to do with how a car performs and Skylines in some areas could be better . You find if you want to thrash a car everywhere close ratio gears work better but keeping a car on the boil , particularly an at times traction limited one isn't always the fastest way to go .

As per having a 4000 rev flat line full boost maximum torque band , thats just not going to happen .

All engines have a sweet point where volumetric efficiency will be highest and it falls off either side of that point .

This is actually an interesting discussion topic because I think people should worry more about torque than horsepower chiefly because at revs torque can go south with killadorks still climbing .

Its torque that gives you the forced induction shove in the back and when it drops off you pull another gear , ideally you want the rev drop to land the engine at a point where it will pull strongly and accellerate you across the middle of its best average torque range .

Some cars are geared to take advantage of the torque they make in every gear , did someone say RS Evos ?

They may run out of revs at only 230 but they can pull 3rd 4th 5th like it was 2nd 3rd and 4th .

Skylines are geared to be sort of sporty road cars and that big 4th 5th gap is easily felt . How fast is a Skyline geared to go at the redline with a 4.1 diff and a 0.76 5th gear ? If it could get there how long would it take ?

The RS Lancer would not be the gun thing to cruise to Melbourne in and let me tell you close gearing is an awkward PITA round town but thats what it takes to have unholy thrust in every gear .

Its this sort of thing that has the potential to make a car a missile and not need 400 Kws to do it . Getting strong accelleration with production gearing all the way through is a big ask and it needs a LOT of torque to achieve it . Manufacturers put tall gearing in road cars because it makes for relaxed cruising and better fuel consumption . They also set the enines up to make good part throttle torque because thats also needed to pull tallish widish spaced gear ratios .

Its another one of those areas that you can't really have both ways and so the manufacturers build what the market wants which is smooth quiet and economical .

With gearing the zoomers need shortish diff ratios and close tall gearbox ratios which is not difficult in an indirect transmission . Direct boxes like most RWDs have should probably go with a direct 5th because thats strongest and set the diff ratio accordingly . This is something like what the R31 Skylines used when raced here and the trans was actually a Hollinger if memory serves me correctly . It had a splined countershaft so the individual ratios could be changed with the gears fitted casett style . I think Nissans 240RSs were also set up with tallish , for rally , 3.9 diffs too .

A .

I think some of you people ask for the impossible at times . I highly doubt that a turbo exists that will make significant boost at 3000 revs and still do it at 7500 revs .

Yeah I think 3000rpm is unrealistic, but if you could get something around 3.5k - 7.5k I don't think that is impossible, at least I'd like to know what combination will get as close as possible, whether that is the gt3071 or 76 I'm not sure which would make a better street car.

Edited by Rolls

I went from a 3071 to a 3076 52 trim with the same .78 rear twin scroll housing. The 3071 just seemed like it was working a lot harder. The "baby" 3076 feels like its doing the job alot easier pulls earlier too (but there were some exhaust changes). If your going to use a twin scroll ex hsg, the difference between the two in terms of spool will be less pronounced than compared to an open housing.

.

iirc garrett make a few twin scroll gt30 housings in t3 flange. but the only option for t4 flanged housings is ATP. im running an ATP 1.06 t4 twin scroll v band housing, its an extremely tight fit but works well.

cant really give you a proper answer as i changed housings at the same time as going from 25 to 30det and only got about 300km driving out of it before the motor had some problems which put the car in my garage, where it still sits to this day....

current 1.06 housing is on a 3l yer. was running a garrett .82 IW housing when i had a 25

from memory (which is very blurred by lots of alcohol since the last time i drove it) it hit 1 bar of boost around 3400-3600 under load (4th gear), but thats with a lot more ignition timing than most people run, which brings boost on sooner time wise but later rpm wise. never had it on the dyno with that setup, do my own tuning so was only gonna chuck it on a dyno once everything was sorted, which hasnt happened yet. imo 1.06 twin scroll is perfect for a 3L, the internal gate .82 was a pretty bad experience for me, all the lag of a gt30 without the power of one due to the restrictive exhaust side.

Edited by JonnoHR31

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • I know why it happened and I’m embarrassed to say but I was testing the polarity of one of the led bulb to see which side was positive with a 12v battery and that’s when it decided to fry hoping I didn’t damage anything else
    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
×
×
  • Create New...