Lets talk rotated

[Bgross129]

If u are running a rotated set up. What turbo or kit ,Ic , intake tube , are you on sd or maf setup ? What's your spool time ? Lets here it guys.


I run a Perrin gt3076 r kit, amr top mount ,ks tech 73mm maf tube. I spool full boost at 3600rpm. This is a built motor .with bc 272 cams ,and +1mm intake and exhaust valve.on stock header car is an 05 Sti

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[Big-Sexy907]

UR rotated kit, hot piping ceramic coated with a set of GT Spec headers. Turbo is a HTA3582, Garret FMIC fabricated by JM Fabrications, DW1300cc injectors, TGV Deletes, Cosworth Intake Mani, Greddy SP1 catback, motor is built, GSC S2 cams, valves/springs/retainers, built and sleeved block, running full SD. Car isn't tuned yet, hoping for this spring.

[Bgross129]

U running open source sd or Cobb ap ?

[Alaskan EJ20]

GT3076, .63 hotside(2.5in), tial 44mm wastegate, perrin big maf, txs frontmount, 900cc injectors, built 257, Sti heads, hardsprings 272 cams, HKS headers,

ran 02 wrx ecu super hacked RomRaider for a while(maf based) , now i have HydraEMS standalone(speed density) i see full spool by 2700-2800 with out AVCS. hoping to add avcs this summer from some added fun

[Bgross129]

That's some incredible spool gabe. I need to do some more tuning. I just got done building my new short block. 1000 miles deep time to turn it up! What boost u running ?

[Alaskan EJ20]

Originally Posted by Bgross129

That's some incredible spool gabe. I need to do some more tuning. I just got done building my new short block. 1000 miles deep time to turn it up! What boost u running ?

my spool also comes from the smaller rear housing turbo i have, exhaust is shoved through a .5inch smaller hole than yours, in terms of area your talking 4.9 inch/squared(2.5inch outlet) vs 7.06 inch/squared (3 inch outlet) your rear housing is 30% larger which moves the spool time later in the rpm. im running 24-25psi pump and meth, considering a 30psi racemap with race gas and meth (1/4 mile only, 10-11 sec of torture for the engine)

[Nomadgene]

Originally Posted by Alaskan EJ20

GT3076, .63 hotside(2.5in), tial 44mm wastegate, perrin big maf, txs frontmount, 900cc injectors, built 257, Sti heads, hardsprings 272 cams, HKS headers,

ran 02 wrx ecu super hacked RomRaider for a while(maf based) , now i have HydraEMS standalone(speed density) i see full spool by 2700-2800 with out AVCS. hoping to add avcs this summer from some added fun

Originally Posted by Alaskan EJ20

my spool also comes from the smaller rear housing turbo i have, exhaust is shoved through a .5inch smaller hole than yours, in terms of area your talking 4.9 inch/squared(2.5inch outlet) vs 7.06 inch/squared (3 inch outlet) your rear housing is 30% larger which moves the spool time later in the rpm. im running 24-25psi pump and meth, considering a 30psi racemap with race gas and meth (1/4 mile only, 10-11 sec of torture for the engine)

We need to have a long conversation!

[Alaskan EJ20]

Originally Posted by Nomadgene

We need to have a long conversation!

yes any day, i love science

[Bgross129]

I'm running a .63 hot side also gabe. So this is not adding up ?

[Bgross129]

I'm on a very fat break in tune. I'm waiting on the dyno. So Seth and I can do some fine tuning on the avcs. My stock header slowing me down on spool ?

[akeric]

Originally Posted by Bgross129

I'm on a very fat break in tune. I'm waiting on the dyno. So Seth and I can do some fine tuning on the avcs. My stock header slowing me down on spool ?

stock header is usually the best for spool unless your making big power 700hp for example.

spool isn't everything, for the most part if you have an sti 6spd your gears are so close together that you can always be in the power band. Might as well have spool at 3500rpm (especially if doing so can help you make more power, i.e. bigger hotside for more topend...) it makes the car a little nicer to drive.

I can honestly say that the evo spools so quickly that I don't like it. I don't need full boost at 2700 rpm, because that means I'm making alot of boost at even 2000rpm. The car always wants to be in boost so the word mild acceleration has been removed from its vocabulary. It makes it a bit of a handful sometimes, and whats the benefit? Maybe helps me from a roll a bit? Racing from a roll is for freaks anyway and spool isn't really an issue at the dragstrip.

Anyway just my thoughts. I want full boost in 3rd gear at around 3500-3700, you can get a 600+hp setup and with spool so late you can still drive it normally but get on it and its a rocketship.

[Alaskan EJ20]

Originally Posted by Bgross129

I'm on a very fat break in tune. I'm waiting on the dyno. So Seth and I can do some fine tuning on the avcs. My stock header slowing me down on spool ?

in the top end yes, and maybe spool also these bb turbos like to breath, timing and fuel can add to spool but its minor. i believe because you have a 3 inch outlet thats where your loosing spool time.

[akeric]

I was under the impression that you achieved maximum spool from having the largest pressure differential between the pre-turbo and post turbo.....so wouldn't a 3" outlet improve spool by removing the exhaust restriction?

[Alaskan EJ20]

Originally Posted by akeric

I was under the impression that you achieved maximum spool from having the largest pressure differential between the pre-turbo and post turbo.....so wouldn't a 3" outlet improve spool by removing the exhaust restriction?

well no, as in your statement "largest pressure differential" having a larger outlet would aid in making the pressure differential less bye allowing the air to flow more freely which means the air is less dense and also flowing slower through that section. having a tight hole creates restriction and more of a pressure differential. too much pressure and the engine is restricted, but you have a good point when it comes to gearing and powerband on the six speed, you only really need 3000 rpms of great power band. but its cool as hell to cruise at 65-70 in sixth and romp it 25psi and your at 100+ with seconds....

[akeric]

yeah but sadly with my power band and gearing I cruise around 3000rpm and even 'mild' acceleration results in full boost, lots of noises, and more acceleration than I generally needed.

[P3Auto]

Don't get too hung up on the AVCS stuff if you can only adjust the intake cam...Guys that claim big gains by adjusting the intake cam timing are not telling the whole story. There are gains here and spool time can be slightly helped with that but its not going to be night and day. This is why a dyno is needed to really fine tune that system...The other methods involve much for information to measure back pressures, air flow, etc. Air is power. More flow more power.

Now on a different note, AVCS systems on 08+ STI motors that have both intake and exhaust cam timing adjustment can see some much more considerable gains. So Gabe who has the newer heads can do a lot more.

Originally Posted by Bgross129

I'm on a very fat break in tune. I'm waiting on the dyno. So Seth and I can do some fine tuning on the avcs. My stock header slowing me down on spool ?

[P3Auto]

My rotated Forester with a top mount spools around 3400 to 21psi. It should also be noted that the gear your in also sort of plays into it. Obviously 4th gear for instance spools earlier then say 2nd perhaps since the 4th gear gives the turbine more time to ramp up vs rpm.

[Muphzilla]

Originally Posted by Alaskan EJ20

having a tight hole creates restriction and more of a pressure differential..

I lol'ed at this even tho I shouldn't have.

[akeric]

Originally Posted by P3Auto

My rotated Forester with a top mount spools around 3400 to 21psi. It should also be noted that the gear your in also sort of plays into it. Obviously 4th gear for instance spools earlier then say 2nd perhaps since the 4th gear gives the turbine more time to ramp up vs rpm.

I consider spool runs to be done in 3rd gear. Just because I do almost all of my tuning for power as 3rd gear runs anyway, so I have a lot of road dyno maps from 2k to redline to see spool on. I have the higher final drive in my car so that helps spool as well by loading up the engine more.

[P3Auto]

I suppose it matters if you have 5 or 6 gears...I personally will tune down low with upgraded turbos just in case someone feels the need to floor the car at 2000-3000 rpm but really that is not realistic. Most of the time I cap the max boost allowed in lower rpm to protect the engine, turbo, and driver! A lot of these cars when you upgrade a stock location turbo there is no option for anti-surge covers and items like that so low rpm high boost usually means flutter, surge, etc of the turbine. Now with the rotated kits they don't seem to care but really if your putting a big single scroll turbo on your moving your power band up anyway.

I have a customer who would call me and complain about low rpm wide open throttle turbo flutter or surge (not a subaru btw). I went in and had to cap his max wastegate cycles down quite a bit to fix it. All the while I am thinking why would you want to go WOT on a tiny motor with a big turbo at 2000rpm??!! Anyway customers always right...

I think it would be interesting to compare hot side turbo sizes on the same car via dyno. The discussion was faster spool with tighter holes, sure but there is a price to pay for smaller hot sides as well. Higher pressures on the hot side pre-turbo also acts like restriction so until that EWG starts to open you have quite the restriction on air flow BUT you spooled faster!

Last though...Look at dyno sheets on cars that have bigger turbos and slower spool. Pick a point pre-peak torque and peak boost and look at the power levels compared to say a smaller even stock turbo. Usually you will find the power output is the same or better on the larger turbo even though your not fully at target boost. Part of the age old boost makes power issue. In other words 15 psi on a vf39 is very different then 15psi on a 3076r. Air flow is our friend...

Originally Posted by akeric

I consider spool runs to be done in 3rd gear. Just because I do almost all of my tuning for power as 3rd gear runs anyway, so I have a lot of road dyno maps from 2k to redline to see spool on. I have the higher final drive in my car so that helps spool as well by loading up the engine more.

[Bgross129]

This thread went way in depth on the subject. Nice that everyone put in there knowledge. Help people make a decision if they decide to go rotated.

[Alaskan EJ20]

good points seth, restriction and pressure also causes alot of heat which we all know what heat does to headers on a suby so there is alot of give and take with a particular set up you just have to analyze what the purpose of the car is and how you want it to perform, i aggree fully that when it comes to turbos the bigger(what ever flows air the best) the better, the car will be much happier with a low boost high air flowing turbo because again pressure makes heat.

brandon you should consider sending the turbo in getting a billet wheel put on the cold side, changes the ~50lbs/min turbo to a ~70lb/min turbo with the same hotside flow characteristics.

[Big-Sexy907]

Originally Posted by Bgross129

U running open source sd or Cobb ap ?

Running Cobb SD, runs great all year.

[Bgross129]

Gabe you going to the meet sat nite ? I would like to meet you in person and touch on this subject a Lil more