CA18 - Gt2871r or GT3071r Top mount ?

[niki205]

hello i need help again for my setup,
Nistune
720ccc or more
z32 maf
forged Ca18
dual catback (xs power) +downpipe and elbow


the car will be mostly for street use
now i have a top mount manifold with my old turbo and my car is LHD... its not very cool for my BMC
Soo for 350-400whp who turbo and manifold will be ok and safety ? satefty (long durability about turbo,engine and ect...)
for the top mount i will need to adapt one elbow and somme adapter for v band for the turbine
i also have a the external wastgate Tial MVS 38mm and i dont know what to made
sell the top mount setup who i have or to run with for more power the top mount is good ?

[Unknown Source]

What cams? Solid lifters and cams you'd hit near the 400bhp mark (I would recommend a better management system as you near the 400bhp mark though) with the 2871r but that would be it's limit, If you want more I'd go 3076r.

The 2871r will fit just fine in the standard position thus saving you a LOT of fiddling around with the downpipes/elbows etc for top mounting.

[niki205]

I have 2 exhaust cams in the head but maybe i will take a tomei pomcams 256in and 256ex i dont know how will be better for the cams duration with stock valves internals the head will be good for how much power ?
and Nistune is not very good for my setup ? with the gt3071r but with the gt2871r will be good for around 320-350whp satefty maybe ? what you thing ?
here i dont a human who can make me the Map for megasquirt i was thinking for Megaquirt
Thanks

[Rubix_Cube]

Do you want more power, or more response? This is important to chose between the 2 of those turbos

[croustibat]

nistune is all right, i know a CA18DET running 500+ HP with it. That and it is plug and play. Megasquirt is a whole new story, you need to change every sensor on the engine, and that really is a pain. Megasquirt is a real standalone, when nistune "just" unlocks every feature the standard ECU has. Nistune is a daughterboard.I would not go the megasquirt route. Maybe my opinion is biaised as i have been using a nistune for years now but really, i could not be bothered to change every sensor, the software suite delivered with nistune makes tuning easy ... as long as you know what you are doing. Remember it just is a tool, you still need to know how to use it, and you still need EGT and wideband AFR sensors (you or the guys who will be mapping it, so get some bungs welded for them)

Make sure your poncams are for hydraulic lifters. If i remember correctly, procams are for mechanical lifters only, but there are 2 different poncam series, one for mechanical, one for hydraulic lifters.

GT3071r will have a hard time spooling before 4000rpm. gt2871r ... it depends, i think there are 21 different turbo combinations that are called gt2871r. TBH i would not go for the gt3071r, it is too big for your power goal.

350 whp would be done with both main variants of the 2871, the .64 and .86 A/R . You will be near the maximum on the .64, which would still offer a nice spool. You could get some room for more power with the .86 , but then it will spool just a bit later. Your choice.


TBH, i would go with a gtx2863r, or a gtx2867r . They are more expensive than a gt2871r, but they also are way better on every aspect (tech used, material, tighter tolerances, power delivery). Your choice, again.

Anyway, you are approaching transmission limits. Prepare to get gearboxes and clutches if you abuse your S13 with 350+ Whp.

[ricardomendes]

when you guys say "GT3071r will have a hard time spooling before 4000rpm" will the turbo start to spool at 4000 or have 1 bar @4000?

the gt3071r with this part number 700382-3 or 700382-5003 have almost the same chra specs as gt2871r with part number 743347-2, the diference is the Turbine Wheel Dia 56.5 to gt30 and 53.9 gt2871, this two with as.64 exhaust, will this make too much diference?

i have almost the same specs as niki205 forged ca18, full 76mm exhaust, dual exhaust cams, nistune, 720cc, but with 8.7 compression ratio.

i would like to go to gt3071r, but don´t want a 3000rpm of usable power band because don´t want to do more that 7800rpm.

[croustibat]

Why would you want to use a 450/500HP capable turbo if you wish for 320/350 ? You are not telling everything here ... Of course, you could get 350hp out of it. But it is kind of wasting.

the exact answer to your question does not exist. Only someone who has the exact same setup can tell you. From what i have seen, 8.7CR, cams and a GT3071r would work well and produce lots of power, but it wont spool fast, meaning you will barely start to get positive pressure at 3500rpm. Use higher compression and better fuel (like e85), and it will spool faster, but dont expect a miracle, a gt3071r does not spool fast on a 1.8L engine.

I highly suspect you just want the cool effect a top mount and a big turbo creates when opening a hood at night on a parking lot ... That would surely look cool, but that wont spool soon. Want sooner spool, then get a small gt2871r or a gtx2863r. And if you so much want it top mounted, get a top mounted mani for it ...

Now there are receipe for a fast spooling gt3071r . They are:

1/ 2.2L+ displacement engine
2/ 25bhp or more nitrous jetting during spool
3/ antilag /bang bang system
4/ dual charging (i.e gt3071r and a small T25 or a compressor)

unless you do one of these, you WILL have a 3000rpm powerband.

[croustibat]

I found an old vid from a friend with a gt3071r. he downshifts twice to get power... first downshift brings him at 4000rpm, then he downshifts again because there is no power. It brings him at 5000rpm. He had a powerband of around 4500 to 9000rpm.

bear in mind he has 272/10.25 cams and mechanical lifters, which means he has more lag. He also has a really nicely ported head, and revs to 9000. But THAT is what you do with a gt3071r on a CA18DET.




funny thing about that engine is that it lasted something like a year at well over 450HP , being thrashed every week ... The thing we did not know is that the machinist used a wrong setting, and pistons were slapping in the bore. It did break the engine block later, when boost was up to 2.3 bar

[ricardomendes]

Why would you want to use a 450/500HP capable turbo if you wish for 320/350 ? You are not telling everything here ... Of course, you could get 350hp out of it. But it is kind of wasting.

the exact answer to your question does not exist. Only someone who has the exact same setup can tell you. From what i have seen, 8.7CR, cams and a GT3071r would work well and produce lots of power, but it wont spool fast, meaning you will barely start to get positive pressure at 3500rpm. Use higher compression and better fuel (like e85), and it will spool faster, but dont expect a miracle, a gt3071r does not spool fast on a 1.8L engine.

I highly suspect you just want the cool effect a top mount and a big turbo creates when opening a hood at night on a parking lot ... That would surely look cool, but that wont spool soon. Want sooner spool, then get a small gt2871r or a gtx2863r. And if you so much want it top mounted, get a top mounted mani for it ...

Now there are receipe for a fast spooling gt3071r . They are:

1/ 2.2L+ displacement engine
2/ 25bhp or more nitrous jetting during spool
3/ antilag /bang bang system
4/ dual charging (i.e gt3071r and a small T25 or a compressor)

unless you do one of these, you WILL have a 3000rpm powerband.

in my case I don't want a topmount nani, the gt3071will fit bottom mount with aftermarket nani like xspower I think.
I would like around 300@wheels.
I made 300 engine hp with 0.9b using t28r...


There's a video of one forged ca18 1.9 cometic with gt3071r with stage 3 chip and 0.5b of boost.

http://m.youtube.com/watch?feature=p...embedded&gl=PT


With cams, lower compression, Ebc, and better mapping maybe it can have better spool.

And I think this was the gt3071r with bigger specs but ar.64 exhaust.