Which turbine size for gtx3071r?

[jamesm]

Originally Posted by diss7

Nice. Certainly comes in early

I think the 0.64 will become restrictive once/if you dial the boost up to 12/14psi; which is where I would look to run a gtx2867r.

it will certainly be restrictive in a sense. the question is does it matter? sr20's have made 480+whp with a 0.63 housing on a gtx2867r at waaaay higher boost than i'll ever use. so it's not whether or not it's optimal, it's whether or not it matters, and whether or not the drawbacks outweigh the benefits.

you could have less backpressure and lower egts with a bigger a/r housing... but if they're not too high with the 0.63 you benefit nothing from it.

[DeBiase]

I was thinking of running 9-10 psi until one day I am ready to dial it up to ~14psi. So you think the GTX2867R would be good. Price isn't really an issue as the kits that sell both the turbos sell them for the same price. It's not so much that the smaller turbo can't do what I want. I just want the turbo to be at a good spot on its compressor map so that the turbo wants to make that power and airflow and doesn't not wear pre-maturely BC I am making it do too much. I'm just learning tho so I do appreciate all the input. I'm simply explaining my concerns. I don't want to make a costly mistake.

[DeBiase]

Wait is it okay that I am asking these things on your thread? I'm now to posting on forums lol.

[diss7]

Originally Posted by jamesm

it will certainly be restrictive in a sense. the question is does it matter? sr20's have made 480+whp with a 0.63 housing on a gtx2867r at waaaay higher boost than i'll ever use. so it's not whether or not it's optimal, it's whether or not it matters, and whether or not the drawbacks outweigh the benefits.

you could have less backpressure and lower egts with a bigger a/r housing... but if they're not too high with the 0.63 you benefit nothing from it.

Agreed.

Although I would really like to see a gtx2867r 0.86 as a comparison with more boost. I see there is another gtx2867r in the FI Dyno thread..
http://www.ft86club.com/forums/showp...5&postcount=11

That has significantly more lag than your setup James. Would have to assume its the 0.86 a/r. Althought I wouldn't have expected it to be as different to yours as it appears to be.

[diss7]

Originally Posted by DeBiase

Wait is it okay that I am asking these things on your thread? I'm now to posting on forums lol.

It's all good mate. Its still related.

I still haven't totally given up on the gtx2867r to be honest, so its good that it's been discussed at the same time, in the same place.

[FA20Club.com]

From testing the .82 AR on the 28 works better even and lower boost levels than the .63. As far as the 3071 or 3076 you can run either on the .63 up to 500hp without choking up top. We recently tested it to that level a few months back. We'll be releasing that build and its specs in the coming weeks. If you want since youre local to us you can come by the shop for a test ride.

[jamesm]

Originally Posted by diss7

Agreed.

Although I would really like to see a gtx2867r 0.86 as a comparison with more boost. I see there is another gtx2867r in the FI Dyno thread..
http://www.ft86club.com/forums/showp...5&postcount=11

That has significantly more lag than your setup James. Would have to assume its the 0.86 a/r. Althought I wouldn't have expected it to be as different to yours as it appears to be.

i'm not sure which housing they use. not sure if the gtx upgrade is just the compressor side or the tial stainless housing as well. i guess that wouldn't matter as far as the a/r though i believe the premium kit uses the 0.63 housing.

[SmsAlSuwaidi]

I was initially planning on using a gtx35 or a precision 6262, but after speaking to my tuner he insisted that a Gtx30 with a .63 ar is all i need, and only difference between the gtx30 to 35 is 500rpms in lag and nothing with power in the sub 30psi range. After 30 psi the gtx35 is going to excel !

id love to hear opinions about this

[nelsmar]

Originally Posted by SmsAlSuwaidi

I was initially planning on using a gtx35 or a precision 6262, but after speaking to my tuner he insisted that a Gtx30 with a .63 ar is all i need, and only difference between the gtx30 to 35 is 500rpms in lag and nothing with power in the sub 30psi range. After 30 psi the gtx35 is going to excel !

id love to hear opinions about this

You didnt mention your power desire, fuel, or engine mods. If OEM engine, E85... i would say 35 is overkill. Depends on what you are going for. 3071/76 has a lot of head room.... hell GTX2867 has people in the 400's on a number of platforms. I am doing a fully forged bottom end and I don't plan on anything over a GTX3071 my self.

[SmsAlSuwaidi]

Originally Posted by nelsmar

You didnt mention your power desire, fuel, or engine mods. If OEM engine, E85... i would say 35 is overkill. Depends on what you are going for. 3071/76 has a lot of head room.... hell GTX2867 has people in the 400's on a number of platforms. I am doing a fully forged bottom end and I don't plan on anything over a GTX3071 my self.

Opps sorry !

E85 most of the time, ill try to squeeze as much as i can from the stock block ! And low boost on 91 when e85 aint available.
Regarding my block its on my wish list but ill run the stock block for a while.

Why not a gtx3076 ? What ar too ?

seems like ill cross out the 6262 and maybe the 35


Sent from my IBrick

[DeBiase]

Originally Posted by FA20Club.com

From testing the .82 AR on the 28 works better even and lower boost levels than the .63. As far as the 3071 or 3076 you can run either on the .63 up to 500hp without choking up top. We recently tested it to that level a few months back. We'll be releasing that build and its specs in the coming weeks. If you want since youre local to us you can come by the shop for a test ride.

Thank you. I am definitely looking forward to that. And looks like you found the post I was talking about before with the boost chart where the GTX2867R has really quick spool time. And great FAQ post by the way. I am sure that will help stop the redundant questions you must often get.

[diss7]

Originally Posted by Sellout

yeah, and? if both are making 350whp, which one is faster?

The GTX3071r car will be, because it makes the power more efficently, cooler air/more timing.

I realise that there is an understanding (that you share) that its best to pick a HP target, and then choose the smallest turbo that can achieve that, and you end up with the largest power band; and then arguably the better street car. And in most cases that is true.

IMO you don't need boost at 2000-3000rpm, if you do, you're in the wrong gear. Building a setup that can boost at this level is sacraficing efficency in the actual power power band, which is at least 4000 - redline.

On the track, on the drag strip, you're not going below 4000rpms (if you are you're doing something wrong)

Saying that a small turbo boosting at 2500rpm to redline, is faster than a larger turbo boosting 4000rpm to redline, that are both making the same peak power, is false. Unless you're talking about rolling start/highway pull racing from very low revs. Thats about the only time your example will be faster.

A practical example of this, on this platform, is the point at which a gt28 frame turbo hits the knock threshold on pump gas, compared to a gt30 frame turbo. Based on that, the gt30 frame turbo can achieve higher peak power, due to its superior airflow and efficency, less turbine inlet pressure, yada yada.

Theres a couple of us in NZ that are about to embark on a gtx2867r 0.86 vs gtx3071r 0.63 comparison. My car will be the latter example.

[dabocx]

Im ditching my gtx28 for the gtx30 series so this thread gets a thumbs up!

[nelsmar]

Originally Posted by SmsAlSuwaidi

Opps sorry !

E85 most of the time, ill try to squeeze as much as i can from the stock block ! And low boost on 91 when e85 aint available.
Regarding my block its on my wish list but ill run the stock block for a while.

Why not a gtx3076 ? What ar too ?

seems like ill cross out the 6262 and maybe the 35


Sent from my IBrick

3076 has a larger compressor but I however have no desire for more power than the 71 outputs. This will be a street car build and occasional track car. I care more about transient lag than high power. Sure I want power... But the majority of the time I will realistically be on a map pushing 300-350whp. I will have a race mode that just maxes out my cars fuel system or turbo for fun but there is no reason for me to go with a 76 when the peak power levels on "race mode" that I desire can be had with a 2867. I'm simply doing a 30 housing for the exhaust back pressure benefits. As it lowers the knock wall slightly on pump gas. I plan on a .63 air and if I'm not satisfied with my top end I will go one step up on housing for. But more top end.

When it comes to transient lag I checked Jamessms logs once on his Iola less desired tune and his lag in I think it was 4th gear at 4000 rpm is a hair under 400ms. Vs the genesis I've been driving lately which has roughly a 2400ms latency under the same load scenario. Throttle response is more important to me. He'll I was tempted to do a high rom build and just reuse my vortech blower as the latency is non existent but the fuel economy will suffer and that's a lot of strain on a belt for a blower at 60krpm