Racecobra

Hi All!

I would like to change my turbo to gain performance. This means power and spooling response. A short summary of my current engine setup:
Engine: KA24DE(T)
Internals: Supertec pistons (9:1 compression), Pauter rods, ARP studs, cometic gasket
Valvetrain: crower 276/276 cams, modified springs.
Exhaust: Mazworks top mount exhaust manifold, 2,5'' turbo back exhaust system
Induction: Cosworth full front intercooler
Fuel: 625ccm injectors, AEM Regulator, fuel pump: 2xBosch(300l/h)
Ingition: AEM twinfire module with individual CDI pencil coils
ECU: Haltech E11v2
Turbo: T3/T4



At the moment I run ~370hp peak horsepower at 1,35bar (20psi) boost with 98RON fuel.
I would like to get better spooling response and 450hp peak. A rough calculation (AFR=12, BSFC=0,48) results in 45lb/min airflow.
I also tried to calculate the necessary boost, but I It's difficult because I have no idea about the volumetric efficiency of my engine. Due to the 276°/276° cams it should be quite good at high rpm. But on the other hand, my intake manifold and valve size is stock.
I think Garret GTX series could be the choice for me.
But I'm not sure regarding the compressor size, trim and turbine housing.
The turbo that come in to question from my point of view is theG TX3067R with 0.63AR turbine housing. What is your opinion?
Is it worth to invest into a GTX series (better spooling?) charger instead of GT?
Or should use an other turbo?
Any other engine modifications recommended?

For me, the spooling response/drivability is important.

Yes, lot of questions, but I have just sketchy knowledge about engines.

Best Regards form Austria,
Matthias

d_nice

its a nice setup

Racecobra

I will use a GTX3071R with 0.63AR housing to get 450HP peak.
Any comments to this turbo in combination with my setup?

ultimateirving

Wouldnt you want bigger injectors too for that goal?

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Racecobra

Yes, the fuel delivery should be considered too. First, I will try to increase fuel pressure (now the fuel pressure is just 3bar). The two 300l/h fuel pumps and the AEM pressure regulator should not be a limitation.

What do you think about the GTX3071R with 0.63AR housing? Suitable turbo for my application?

BR Matthias

RalliartRsX

^^ I think what he is saying is that, those 625cc has a ceiling of around 420WHP (a little more at 4bar but not at your 450WHP limit) at pretty much 100% duty cycle.

Basically, for you upper/peak HP limit, you do not want to run more than 80-90% of the injector limit, as some injectors, once they go static (above 95% in some cases), they fail almost immediately.

Best bet is to go 1-2 sizes up (say around 750-800cc injectors)!

brndck

I'd suggest 740 injectors, the gtx3071 is a good choice. You also will want a larger throttle body and possibly aftermarket intake manifold.

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PoorMans180SX

Just to be clear here, the GTX line doesn't really spool faster than their GT brothers, they are just more "efficient". And seeing that you make 370whp now, I'm thinking you're not going to find a turbo that makes 450 and spools faster, unless you're moving to a twin-scroll setup.

You will probably want an aftermarket intake manifold.

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fliprayzin240sx

I'd probably even suggest some SARD 850. I've seen 740s max out around 450-460 range. Better to have a bit more just in case.

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^^^ I Agree with Him!

Personally I'd Recommend

JWT Fuel Rail
ID1000cc injectors
Tomei FPR
DocRace Twin Scroll T3 Manifold
GTX3071R with .82 A/R divided Housing.
Full 3" Exhausts.
Turbosmart Comp40 Wastegate.

as far as turbo goes, partly why it's so laggy its because of the really big camshafts that you have. I would change your camshafts out for some JWT Camshafts that'll give you better mid range HP and more TQ down low. the GTX3071R will be a good turbo for 450+hp. I recently Tuned a completely stock block and head RB25 using California 91 octane fuel and made 422whp at 17psi peak (around 4K rpm) and boost fell off to 14psi by 7700 RPM. made peak hp at 7300RPM. so with only 0.1L difference in size and a more efficient cylinder head that you have on your car you should have no problem hitting your 450whp goal with a GTX3071R all parts which we can supply for you

-Juan

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Racecobra

Thanks All for your response!

I realize, that I have to upgrade the injectors.

I always thought, that the main advantage is spooling performance. Because if I compare the compressor map of the GTX3071R and the GT3071R, both have 77% peak efficiency. Yes, the GTX has a wider range with high efficiency.
http://www.turbobygarrett.com/turbob...R_803712_1.pdf
http://www.turbobygarrett.com/turbob...00382-3_20.pdf
Thanks, for the hint.

I have installed a large AEM fuel regulator and two bosch 300l/h fuel pumps, each has its own filter.

So I think I don't need the tomei FPR.

I can't find a docrace twinscroll manifold for the KA24DE, but fullrace offers one: Nissan KA24DE Twin Scroll Turbo Manifold - Full-Race.com

I have some questions regaring twinscroll:
1. Are there internal gated twinscroll turbine housings available?
2. My understanding is that twinscroll seperates the exhaust pulses to optimized flow and spoolup. But if I use just one wastegate, the exhaust pulse are not separated any more. Will this weaken the positive twinnscroll effect? I have also seen twinnscroll setups (on RB25 engines) with two external wastegates. (this will become expensive, because I have to change the manifold and add two external wastegates, dumppipes, etc)

Regarding Camshafts, so you think the 276° crower camshafts decrease spooling performance because of the large valve-overlap and the bad filling at low rpm? Hmm, I changed the cams last year and they helped a lot achieve the 370whp (yes response is peaky). I will think about this interesting argument. Which JWT cams would you recommend?

Thanks a lot, your inputs help me a lot!

BR Matthias

240sxfan6882

Some twin scroll manifolds that use a single WG have a divided WG tube also that seals up against the valve on the WG (I would imagine FR does too), therefore still keeping the pulses separate until the WG opens.
The WG valve is really close to a "septum" that seals up the pulses.

You can see wtf im talking about on this pic:

codyace

Couldn't have said it better myself

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Racecobra

Thanks, this makes sense. I will ask FR about the construction of the manifold.

Do you think it is worth for me to go twinscroll?
Are internal wastegated GTX/GT twinscroll T3 turbine housings available? (The only twinscroll turbo I found is the Borg Warner EFR Series).

[email protected]

as far as my knowledge goes there is no Twin Scroll Internal gated housings available from Garrett. so a new manifold might have to be done.

reason behind twin scroll is that it's much more efficient not only on spool up but on the overall power band, with the addition of better suited camshafts for your application.

the camshafts i would recommend for your situation would be the JWT S1 for the KA24.

you can never go wrong with FUll race manifolds, if you have the bank roll i would definetly buy that. but other than that DocRace should be able to fab you up a Twin scroll manifold give him a call too!

-Juan

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Seraphim38

Go external wastegate. Twin scroll is more responsive.

I have a GTX3076R on my SR20DET and it spools up faster than my old GT2871R did, and makes 100+ more hp everywhere on the dyno. I can post a pic of the dyno readout if desired. 460rwhp on pump gas on the break in tune and a lot more room to go. The tuner said I should go back so that we can spin it up to over 500 at the tire.

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SlideOrDie831

you will benefit from a twin scroll setup. swap those 276 cams with JWT cams.

Def

Your Mazworx manifold is just fine. IMO, twin scroll gives a slight boost in VE, but it's nothing that a little time on a dyno with cam gears couldn't find (or more gains) and no one even bothers with that in the Nissan world for some reason. Twin scroll is expensive given you already have a decent single scroll setup.

IMO, a regular GT3071R will do about 450 rwhp running it to death, but the GTX3071R will do it much more comfortably. The biggest difference on the billet wheels is the smaller hub boss, so they have a little more flow area, and you get roughly GT3076R flow for about the inertia of a GT3071R.

Your biggest issue is the 2.5" exhaust, definitely make that a 3" exhaust with good mufflers and you'll see huge gains.

The GTX3071R will definitely outspool your old T3/T04E, so I wouldn't worry about that. I might even think about using a 0.82 A/R hotside personally, since that is a better fit for a >400 rwhp KA IMO. But if you're mostly on the street I think you'd like the 0.63 more.

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Racecobra

Hi,

Thanks for the answers again!

The exhaust-system will be changed to 3" and 740cc injectors with more Pressure (or 850cc). Than the fuel System should be fine. Ignition system is also sufficient with the AEM twinfire module I think.



On the Webpage, I can't find twinscroll manifolds for the KA.

So you mean adjusting the cam phase has the same effect as a twinscroll turbo setup? It makes sense that optimized cam timing increases VE, but how could this effect spooling time? More VE means more exhaust gases and more turbine flow, but is that effect the same as twinscroll (regarding spooling)?

Due too the answers I think a GTX3071R is a proper turbo for my engine.
The question for me is, change the manifold and go external gated with a GTX3071? Or keep the mazworks manifold and use a singlescroll housing?

Any comments about the borg warner EFR series? They are twinscroll and internal gated, so I would not need a external wastegate and dumptube.

BR Matthias

Def

Altering the cam timing does not make the turbo act like a twin scroll. But it does change the engine's powerband.

This is exactly what Nissan's VCT did on S14/S15 SRs. It just step changed the intake cam's phasing by about 20 crank degrees IIRC. So you could advance it and really help the bottom end and bring the turbo up to speed earlier, then let it go back to the retarded position for better cylinder filling as the stock setup's exhaust port pressure increased. This is also why it doesn't do that much for power when you put big cams on the engine and free up the exhaust. You've essentially got so much cam that moving it 20 degrees ends up hurting large parts of the powerband almost as much as it helps it.

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Q.Smooth127

that is a bread and butter top mount setup for any KA/SR with a fairly decent budget (not over kill with bling bling full race stuff even though they do look more nice and baller on your "mod" sheet when you wanna show off haha)
if you aint goin for the 350whp bottom mount gt2871r setup, this one is the way to go for 400+ no problem.
Plus you already using a dual fuel pump setup, so your fuel delivery will be good once you get those larger injectors. Always best to get some slightly bigger but not like crazy crazy big like trying to use 1600cc injectors to just get 400hp ... but enough so ya dont have to max duty cycle the damn stuff. Thus its always nicer to have em a lil larger cause you never know if you wanna try get "just a lil more" power during the tune session cause everyone likes power . Thats why i always hate seein dudes buy 550cc injectors and say they wanna hit like 400whp wit those. Just buy the bigger 740s or 850s if the chance deems itself, cause you can always de-tune/de-power the setup to fit your needs. Better to have a lil extra then push it and then ... shit not enough lol. I mean im not some ultra turbo+fuel setup guru, but we all here to just chime in right

and +1 on JWT cams. i wanna sell my dam BC3s for some nice JWT ones haha. But man those cams are like almost 600 buckaroos n id prolly need to sell all my BC springs n shit n grab JWT spring kit so i dont mix BC stuff with JWT stuff
i need to convert guys on the islands to start usin JWTs, they all just love their tomei poncams lol

redline racer510

2.5 inch exhaust?

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