T78 drivability

[BNR32]

I looked at going bigger turbos or turbo. My BNR34 N1 turbos supply plenty of power for an all rounder (440HP at all four, 500 RWHP, 600 ENGINE HP) so i have decided to keep the setup the way it is.

A friend who has a fairly standard 32GTR took my car for a drive and felt no difference in drivability from his except my car came on alot stronger once coming onto boost and then much much stronger from mid range to top end.

Turbos arent the be all and end all...I know another GTR that has a shmick HKS t04R kit on stock engine with the right fuel and ignition timing tune and right fuel mods. The thing only makes 385 RWHP compared to my 500RWHP and my turbos are rated at 100HP less air.. I think alot of it is due to camshafts, intercooler, oil cooler and all the other bits that add up at the end of the day.

Ive driven a gtr with a big turbo and was not that impressed. I driven gtr's with smaller bolt on GT2540 & GT2530 kits that are nicer to drive and actaully feel like they have more stomp because you can actually feel the torque working to youre advantage, not frying the wheels.

SydneyKid is right, im not aware of any quick tsukuba track cars that make much over 650HP. I once read an article (attempted to read) from option magazine that was showing the power difference to weight advantages of big turbo kits on track cars.

The big turbo kits weighed more, developed power at the wrong time and within too narrow a power & torque band, the cars required much large brakes & clutches and hence even more weight, bigger fuel systems were needed, fuel economy was down and engine rebuilds were a more common occurance.

The smaller turbo kits supplied broader power and torque bands, required smaller lighter clutch and brake setups with less reciprocating mass, used less fuel and had lighter fuel systems by carrying lighter loads, engines lasted longer so more time was spent tuning suspension and lap speed..

Not all of the above principles relate to street driving, but most do. Big kick arse turbos are good for two things: 1. Gloating horsepower sheets to your mates 2. Drag racing

If you want an all rounder with shitloads of power under the foot, go buy a set of Apexi t517/8Z low mount turbos, HKS GT-RS or a set of td05-20g high mount turbos, im sure if Kier Wilson decided to go track racing or all rounding instead of drag he probably would have kept his smaller td05 or small td06 turbo setup, over the larger ones he runs now.

TG

[siksII]

BNR32, a guy in another thread in forced induction has gtr-s's, they come on full boot (1.3bar) at 5400rpm in third, i personally dont think that would make them a good all round choice, t517/8zs are a similar deal arent they?

i think gtss's would be the more logical choice, or even N1's are a lot less laggy than gtrs's

[go_nuts]

What about the Garrett GT28R? They're rated 310-320hp and decent priced, cheaper than a pair of used N1's even.

[Lithium]

Lithium: this thread is more about how laggy single's can be compared to twins, looks like the twins have wins it hands down...for me anyway. Who cares about their bearing type

I understand that, but the comparison (aside from N1 turbos apparently) were between a plain bearing type turbo vs. twin ball bearing type.

Shouldn't the comparison be between a single and twin turbo of similar technology? ie, twin GT2530s vs. a GT3040 or something like that?

[hungry6]

The funny thing is see here and alot on other car forums is alot of ppls aspires to setting their car up in similar fashion as a dedicated track car would be done, also ppls gives out advice how to set up cars and drawing correlation with other track car, but in honesty, how many of you ppls actually drive your car on the track more than once a week for extended period of time. Of course there always will be an exception, but the plain truth is that many skylines rarely sees a track, and if you ever drove on the rd as you would have on the track, your license isn't going to last a morning. So as to setting up a car, it's very much a personal choice and getting good advice is priceless, but don't be rail rd by anyone, every set up is going to be different there are some main points to be consider are: performance criteria - cost - durability.

just some food for thoughts as there is no such thing is one is better than the other without looking into the intent of the set up.

[go_nuts]

Good point hungry6 but like I've said up there, I am after an all-rounder so I can try out whatever I like with it in respect to motorsport choice ie drag, track, supersprint..a setup that will give me respectable performance in all these sort of thing.

[Lithium]

OK, the reason I started defending single turbos is partly because of this point. In NZ Nissans are used by quite a lot of people very regularly for drifting, which is getting to be quite a big thing here. There are countless GTSts, Cefiros, Laurels and Silvias with RB20/25/30DETs running various setups and being thrashed on the track at least monthly (which is quite a bit) as well as being driven on the street, and some used for drag as well.

This means that people have had to find combinations which are affortable to setup and maintain, and are able to function in different environments. The reason I mention single turbos, is there is only one twin turbo car used in the NZ drift scene - and drifting is obviously a sport you want good power and DEFINATELY want good response and midrange torque. The car running the twin turbos is a Cefiro with an Rb26DETT running the stock turbos, so its not that he decided to buy aftermarket twins.

There is an RB25DET powered Nissan here running an XTR 3040 (afaik rated to happily over 500hp) and is on one of the top drifters car, and its blatently obvious that the guy has all the midrange power and torque that he needs with little compromise considering. I'm not 100% sure what would parallel this turbo in terms of twins, but I'm pretty sure it would cost quite a bit more to go down that path - and you obviously have twice as many things to break.

[underground]

I went with an Innovative Dual Ball-Bearing T66 turbo, .7 a/r divided..

I was also going for a daily driver setup that would give me good power (500-550 rwhp) on my 2.6 motor, but wouldn't require me to rev to 5K to see boost...

With the dual ball-bearing setup, I expect to see boost come on around 500 RPM faster than the normal journal bearing counterpart. I would expect to have boost around 4K, which hopefully will allow the car to be very streetable...

At $1700 US Dollars, it was quite steep...

We shall see...

[dairyboy]

$1700USD isn't that steep mind you, for $2k AUD (which is approx what $1700USD is) we can't even get a single HKS GT2530.

[RTFGTR]

NOOB COMMENT...

If you want you car to be streetable than what's wrong with the boost KICK'en in at 5K? Last time I checked my street driving did not involve too much boosting B4 I hit the speed limit and I think that half of you against high boost settings are BOV freaks that like the sound (it's a odd excuse for your fettish)

As for it being a crap track set up... I'm in two minds on this one (+ have not had any track work under my belt yet... 17th @ Sandown is the first) Will share thoughts after first track day.

[Sydneykid]

If you want you car to be streetable than what's wrong with the boost KICK'en in at 5K? .

Ahhh plenty, when tyou change from 1st to 2nd gear the engine revs drop by 3,000 rpm, So if you change up at 7,000 rpm in first you will end up at 4,000 rpm in 2nd. That means no boost until it reaches 5,000 rpm. Oooops that's not good for a fast time or beating that ........

[RTFGTR]

Ahhh plenty, when tyou change from 1st to 2nd gear the engine revs drop by 3,000 rpm,  So if you change up at 7,000 rpm in first you will end up at 4,000 rpm in 2nd.  That means no boost until it reaches 5,000 rpm.  Oooops that's not good for a fast time or beating that ........

Thats a con for track work - not day to day driving.

I have heard of the "sydneykid" and in now way want to get into a tech. argument with you, but your quote from my post was highlighting the advantages if any about a turbo that kicks in @ 5K for day to day driving...

But you only gave disavantages of track work on this set up in your reply?

TRUE you are about the track stuff and depending on how involved I get with fanngin around tracks I have no intention of changing soon (I love it to bits... T78 that is)

[hungry6]

I can attest that i'm no way bias toward a large single t78 or what eve.r it's that i've driven and owned both, very responsive twin set up and a so call "lag monster 78" as refered by some ppls. Trust me unless u own and drive a modified rb26 with a t78 u have no idea how tractable the car is, u donot need all of 700 hp to get the car off the lights all the time, as there is plenty of power off boost to keep the car moving, and i'm not talking about trying to keep up, off boost a good rb26 would be producing conservatively 300hp, so where does that put u in amonsgt the joe average car owner.

On the other hand a responsive twin set up feels thrusty all the time and feels jolty 100% off the time, as the car spend most of it time on boost and u don't need all 600hp+ instantly under your right foot in general traffic.

Good twin have their place at a lower power levels maybe about 350-400ish but beyond that a big responsive twin is a track only proposition.

This is just my personal experience from my own driving style, but everyone else might be different with their right foot.

[Sydneykid]

Thats a con for track work - not day to day driving.  

I have heard of the "sydneykid" and in now way want to get into a tech. argument with you, but your quote from my post was highlighting the advantages if any about a turbo that kicks in @ 5K for day to day driving...

But you only gave disavantages of track work on this set up in your reply?

TRUE you are about the track stuff and depending on how involved I get with fanngin around tracks I have no intention of changing soon (I love it to bits... T78 that is)

I was talking about road and track (circuit and drag). It is very frustrating waiting for the boost to come back after you change into second. And the lower rpm you use in first the worse it gets, ie; you wait longer for the boost to come back.

A few examples might help;

Change up at 7,000 rpm, drop to 4,000 rpm, wait for revs to rise 1,000 rpm for boost to come back

Change up at 6,000 rpm. drop to 3,500 rpm wait for revs to rise 1,500 rpm for boost to come back

Change up at 5,000 rpm, drop to 3,000 rpm and never get boost at all.

On the road I like to be able leave the repmobiles behind without reving the crap out it.

[Sydneykid]

I can attest that i'm no way bias toward a large single t78 or what eve.r it's that i've driven and owned both, very responsive twin set up and a so call "lag monster 78" as refered by some ppls. Trust me unless u own and drive a modified rb26 with a t78 u have no idea how tractable the car is, u donot need all of 700 hp to get the car off the lights all the time, as there is plenty of power off boost to keep the car moving, and i'm not talking about trying to keep up, off boost a good rb26 would be producing conservatively 300hp, so where does that put u in amonsgt the joe average car owner.

I have a 650 bhp RB31DET (3.1 litres) and it doesn't make 300 bhp off boost, in fact it doesn't even make 200 bhp off boost. An RB26 (2.6 litre) would have no chance and we have 2 of those as race cars to compare with.:cheers

[dangerous_daveo]

Ok strange question here then. (just trying to learn, not really having a go at anyone)

1st thing, I dont know of that many big turboed cars that make much boost in 1st (most of the bigger turbo cars I know of tho are light cars, and dont really produce much load in 1st) So 1st to 2nd shift I'll ignore for my question, also I dont think 1st would be used in track racing enough to worry about it.

So my question being, if you change gears at say 7000rpm, and as pointed out the revs drop to say 4000rpm, wouldnt the turbo still be spinning like the blazers? so effectivly once its spinning your emininating a lot of the turbo lag? Obviously a good set up would be needed for this but yeah.

And now just something I have noticed on a mates car, and I really dont think you have a good set up if your boost is coming on at 5000rpm, or its a VERY big turbo.

But yeah, he runs a T04r, custom manifold, dump exaust etc, 45mm wastegate, no AFM etc, the engine is a 2L (1ggte) and is internally STOCK, no cams no nothing, he has a small hole in the manifold somewhere, and a manifold gasket is going, its running haltech, etc, and weights in around the 1000kg mark. Now this car starts making boost with this set up at about 2700rpm, and full boost (25ish psi) at say 4000rpm (might be 3700rpm or so). Now as much as its a smaller turbo than what we are talking about, its also a smaller engine, and a much lighter car (ie less load). So yeah, my point is, how is it going to be a big problem if its set up correctly? (and he can still set it up better for less lag, smaller cooler, shorter wastegate piping, have the manifold designed differently so it 'pulses' more)

My thoughts anyway.

[RTFGTR]

I was talking about road and track (circuit and drag).  It is very frustrating waiting for the boost to come back after you change into second.  And the lower rpm you use in first the worse it gets, ie; you wait longer for the boost to come back.  

A few examples might help;

Change up at 7,000 rpm, drop to 4,000 rpm, wait for revs to rise 1,000 rpm for boost to come back

Change up at 6,000 rpm. drop to 3,500 rpm wait for revs to rise 1,500 rpm for boost to come back

Change up at 5,000 rpm, drop to 3,000 rpm and never get boost at all.

On the road I like to be able leave the repmobiles behind without reving the crap out it.

Well I was talking about the road (public) and if I were to change gear in second at 7000rpm

A. I would be breaking the law on ANY road or highway in Australia

B. I don't drive my car stupid carzy all the time (I have lost my licence 3 yes 3 times and don't plan on doing it ever again) + driving on boost all the time sucks all your juice and @ $1.15 per ltr it's like economy style (kind'a... still drinks shitloads)

Now track...

Yes you are right and I could not agree more about the looooooong wait for the boost to kick in and I do find it annoying when some jerk off catches you off guard (repmobile or whatever).... but if need be you know you could always catch up in a sec or two while waiting for boost. So... yes a T78 is probably not a good choice for the track but the thread headding is T78 drivability.

[Roy]

From what i can tell with the track, as long as your car makes reasonable power at 4,000rpm in 3rd gear then that will get the job done. Sure there are occassional corners that could be quicker in 2nd, but i find typically ppl (including myself:() wash off too much corner entry speed when rowing back to 2nd.

If you take the corner in 3rd gear you may find you carry more speed into and thru the corner so therefore carry a few more revs and chassis is less jittery and not as darty when in 3rd.

So just an observation of mine...but smaller twins do seem to be all the rage:)

[vspecv]

i have owned 4 x t78 cars and at the time i thought they were ok, but since then ive had a t51spl and now a custom bb garret, the t51 and garret are far superior, i will NEVER go back, i can make more power with either of the above turbos and still have reasonable driveability.

Why would u want to toot around off boost anyway, i like to drive my cars and use the power, t78 are just nasty for a everyday street car.

i would suggest anyone who owns a t78, drive a twin turb car or decent single car with similar power and im sure u will see the light too.

[siksII]

Well I was talking about the road (public) and if I were to change gear in second at 7000rpm  

A. I would be breaking the law on ANY road or highway in Australia

B. I don't drive my car stupid carzy all the time (I have lost my licence 3 yes 3 times and don't plan on doing it ever again) + driving on boost all the time sucks all your juice and @ $1.15 per ltr it's like economy style (kind'a... still drinks shitloads)

Hey, maybe you should get a car that comes hard on boost while you are still under the speed limit, then maybe you wont lose your license again, i know if i had your car i would want to enjoy the boost as much as possible (and be wayy over the speed limit of course with the gearing of a gtr!) just an idea

(i know i was enjoying hi-rpm power and the resulting speed when i lost my license )

i think its a bit odd sydneykid is using 7000rpm for an example of why the t78 would be crap because it falls off boost, as for an rb26 you would be shifting at 8000, revs drop 3000 and you wouldnt wait for more boost... you dont shift that early do you?