Recommended A/R Turbine size w/long tube headers
 

I would like to know what is the most recommended A/R turbine size for 1.8 engines with long tube headers with some many turbo sizes is not easy to match a turbo with a long tube header manifold.

The engine is a 1.8. Please post the size of your turbo, A/R turbine size and spool characteristics for that particular turbo with long tube manifold. Moving from a log manifold to tubular exhaust I actually lost midrange power with this present set up.

The car will not be used for autocross or road course. It's for a street car

Thanks!

What is your current setup? What turbo, what A/R?

I don't have a turbo yet. All I have is the exhaust manifold, downpipe, and everything else. I am going to buy a turbo but that depends on the feedback I get from this board. The car is fully built except the turbo.

I sm going to either a GTX2863 or 2867, no EFR turbo here

Very few people use those turbos, so the data is still out. However, there are quite a few that run the 2871/76 so if that is useful I don't know.

Here is the most recent "spool" data from the "I want your spool data" thread. Mind you, this doesn't tell you power, only how fast it achieved a target PSI.

https://www.miataturbo.net/attachmen...ine=1428440340

Thank you for the graph, however it doesn't say much about A/R turbine size. I guess I am gonna have to search each member's build thread to see what turbo combination is in the car.

I don't understand, how did you lose power from log to tube, if it isn't turbo yet? Did I miss something? ??

I don't get it. Are you looking for a turbo recommendation based on one small piece of information that's useless without context? Or a recommendation on what meaningless ratio without context we should give based on one small piece of information that's meaningless without context?

Please advise.

to answer some of these questions let me say the following. I owned several turbo kits

1. FM manifold with 2554 on a 1.6- amazing turbo response with declining power at higher gears (unknown A/R)
2. FM manifold with 2560 built 1.6 - amazing turbo response more midrange power declining power in higher gears (unknown A/R)
3. Begi t3 cast manifold external wastegate built - 1.6 - T3/T04 turbo .48 turbine housing slow spool
4. Begi t3 cast manifold external wastegate - 1.8 - T3/T04 turbo .48 housing - amazing power best combo for ultimate power
5. Long tube header manifold built 1.8 - Garrett non ball bearing turbo T4 .58 turbine housing. Slow as fuck

6. Presently sold the turbo to a local buddy and looking to upgrade for a turbo that gives more midrange power. Upgrading from a T25 ball bearing turbo on a short cast manifold allowed to understand how much fun are these T25 turbos. The present goal is to go down in turbo size to get have more fun driving the car. Need to know what is the best A/R size for a street car.

I see Tial has 3 different turbine sizes for T28 turbos. they are .52, .64 and 82. The TiAL .52 housing looks interesting but I am concerned it will create a lot of backpressure. I think I should go for a .64 housing although the T3 with .48 housing is fucking awesome combo for the 1.8 powerplant. Last upgrading the exhaust manifold from cast to tubular gave me slower spool but that's because I was running low boost on a big turbo. The car has a Hydra now, so I plan to raise the boost.

So are you looking for a turbo recommendation? Or an A/R recommendation? What are your goals?

Here is some of your info. Turbine A/R is only part of the story.

First question I am already set for a 2863GTX or GTX2867 turbo, second question I would like to see what A/R turbine size is best recommended for a long tube header manifold on a street car. My goal is achieve more midrange power with this set up I have now.


Thank you man!

Use the smaller one.

.64 A/R is sufficient for most cases until you bump up the boost or have a high redline, if you push 16+psi you'll want to start looking to step up your A/R size so you can flow more exhaust. Note you'll lose spool performance with a bigger A/R, I recall reading tubular headers breathe better up top but log headers spool faster, so you might suffer double the loss of spool performance.

The decision was made. I am going with a .64 A/R TiAL housing. While I have great results with a T3 .48 A/R and the TiAL .52 will probably give the car tons of midrange power, the .64 is possible the best choice for this car. Thanks everybody.

I have a GTX2867 and .86 and don't see 10 pounds until the top side of 4000, I don't think. I'm usually watching the road.

I guess I could datalog but I don't have a Sharpie handy.

It also depends on your power goals and spool-goals. I ran a .86 hotside on a GT3271, which is a T3 journal bearing turbo and it was around 4,500 before it would hit 28 PSI. Kind of laggy but had a good top end power for what it was. That particular turbo was compressor-limited though at higher boost pressures.

I think a .64 will be fine for your setup as long as you are not running 20+ PSI on it. If you're going to max the compressor out a larger a/r turbine will drop your turbine pressure which helps reduce detonation.

I have a .72 on my 2863, but that's because it's the only A/R available with the v-band EWG port. If I could have gone .64 I would have.

Mine makes 200 kpa at 3650.

--Ian

Seriously this is not bad. If you go down in A/R size the spool should increase considerably starting from about 3000rpms. Quick question, I couldn't find pictures of your turbo set up. Do you have a long tube header manifold?

No, it's an FM cast manifold.

Build thread here: https://www.miataturbo.net/build-thr...rebuild-81161/

--Ian

I love this.