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Old 08-01-2014, 04:34 PM   #1
Speed Addict
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Subaru Banner Slow Spool up + Narrow Power Band : 473whp STI w/ CS600 Cosworth Longblock

I have a 09 STI with a Cosworth CS600 Longblock with the supporting parts/mods that are listed after the text below.

For now, hp is satisfactory as the car has been Dyno'd recently with 473 awhp @ little under 7k rpm with 1.7kg (+-24 psi) turbo boost. The issue is that I have slow spool up for a GTX 3076R turbo and when the wastegate does open it snaps to 80's-F1-style all or nothing binary power delivery.

I've had many turbo cars including a much missed GC8 2000 Impreza but none of them were even close to this kind of all or nothing narrow power band.

Don't get me wrong, I'm very happy the car is awesome and a riot do drive, but, I do track days and the first and only TD I took this particular car I was losing traction on all fours when the boost kicked in around 4650 / 4800 rpm on Pirelli Stock Car Slicks, in second gear. This cost me dearly on my lap times and to make matters worse, I hit the stock rev limit all the time and the rpm drops below the narrow power band on every gear change.

My tuner and I have a few ideas of what would improve spool-up time in theory, but, before I spend more of my hard earned money on parts I would really appreciate some input from anyone that feels they can contribute on what would be their course of action.

I can post the dyno chart if anyone thinks it will be usefull.

Thanks in advance!

Parts List:
Cosworth CS600 longblock - 2.5L 8.21 CR Forged Crank, big valve headers w/ high lift cams + titanium springs and retainers
Custom G&R Reinforced deck treatment
Garret GTX 3076R Externally Gated Turbo (standard location)
Tial MVR Wastegate
Tial outlet pipe for ATP GT30
Perrin FMIC
Perrin Turbo 3" Inlet Hose
Samco Radiator Hose Kit
K&N Cone Filter
DW 265 Series Fuel Pump
DW 1000cc topfeed injectors
Cosworth High Flow Fuel Rails
Cosworth TGV
Cosworth Heavy Duty Timing Belt
Aeromotive Fuel Regulator
Tomei Fuel gauge
Tomei Fuel Rail Adaptor
Killer B Performance Large Oil Pan
Killer B Oil Pickup
Killer B Oil Baffle
Grimmspeed Boost Control Solenoid
Braided AN Steel Air Lines
Braided AN Steel Fuel Lines
Braided AN Steel Brake Lines
Perrin Master Cylinder Brace
DBA 4000T3 Slotted Front Rotors
Ferodo DS3000 Pads
Invidia Catless Downpipe
Invidia Up Pipe
Invidia Q300 Cat Back Exhaust Titanium Tip
Grimmspeed Exhaust Manifold Cross Pipe
Custom G&R front air ducts for rotors
Exedy Twin Disc Clutch
Kartboy/Turn In Concepts Short Shifter and all Bushings
Eibach Prokit Lowering Springs
Eibach Rear Swaybar
Whiteline Rear Camber Bushings
Whiteline Camber Bolts Front
Whiteline Antilift Kit
Whiteline Subframe Rear Traction Kit
Whiteline Steering Rack Bushings
Defi Red Racer EGT Gauge
Defi Red Racer Pressure Gauge
Defi Red Racer Boost Gauge
PLX Air Fuel Ratio Sensor Module and Single Gauge Combo
Perrin Gauge Pod adapters
Perrin Dual Gauge Pod

Parts that will be bought before more track duty:
Mishimoto Oil Cooler Kit
Mishimoto performance Radiator
KW V3 coilovers
Cusco Top hat
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Last edited by Speed Addict; 08-02-2014 at 03:40 PM.
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Old 08-01-2014, 05:20 PM   #2
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Smaller turbo and more boost will pick you up some midrange power. What intercooler?
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Old 08-01-2014, 05:22 PM   #3
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Better fuel and/or higher redline. Smaller piping on ic or get an water:air ic...get a smaller rear housing on your turbo. Idk, too much to list, we could go on for days. Oh yah, go back to the stock cam!!!!! Higher lift than stock on a pumped up 30r ftl...

Cosworth longblock, what? are you a billionaire?

Last edited by CatfaceType-R; 08-01-2014 at 05:27 PM.
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Old 08-01-2014, 05:32 PM   #4
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Originally Posted by CatfaceType-R View Post
Better fuel and/or higher redline. Smaller piping on ic or get an water:air ic...get a smaller rear housing on your turbo. Idk, too much to list, we could go on for days. Oh yah, go back to the stock cam!!!!! Higher lift than stock on a pumped up 30r ftl...

Cosworth longblock, what? are you a billionaire?
I srewed up and quoted the wrong post first, newbie move. sorry.

I went car-less for 2.5 years and had it put together during that period of time, lots o work.

I suspect bigger inlet e exhaust manifolds would help, but, got no firm position from anyone around here.

Another suspicion is bad aerodynamics in the housing w/ external wastegate

As you said, just so many variables I don't really want to shoot and then think.

Thanks!

Last edited by Speed Addict; 08-01-2014 at 05:38 PM.
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Old 08-01-2014, 05:42 PM   #5
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Quote:
Originally Posted by slowgenius View Post
Smaller turbo and more boost will pick you up some midrange power. What intercooler?
I totally agree that in theory that would be the way to go, but, I just can't accept that with my current setup I an not spooling at 3500 / 4000 rpm. There really is no clear reason that it should be this laggy.

I would also compromise hp and/or reliability going down that road.

I'm running a Perrin FMIC kit.

Thanks for the input!
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Old 08-01-2014, 08:42 PM   #6
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No problem. Without a boost plot or dyno graph its hard to see if you are really laggy
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Old 08-01-2014, 11:33 PM   #7
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This boy needs some e85. I'd say also that you would be better with smaller piping and possibly that ATP just sucks. What fuel are you running? There is a few threads with EFR turbos pushing more power and quicker than your setup by a lot. One is kellys he's destroked with reverse manifold efr7670 and his hits powerband ~4K and rides that baby to redline 8k.

What are you using for boost control? Potential the wastegate is blowing open? I cannot understand how short your powerband is.

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Old 08-01-2014, 11:40 PM   #8
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Originally Posted by slowgenius View Post
No problem. Without a boost plot or dyno graph its hard to see if you are really laggy
https://plus.google.com/105481867873...67873947380594

I can't upload the image for some reason but the link above works.

Thanks a lot!
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Old 08-01-2014, 11:57 PM   #9
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Quote:
Originally Posted by Razgeiz View Post
This boy needs some e85. I'd say also that you would be better with smaller piping and possibly that ATP just sucks. What fuel are you running? There is a few threads with EFR turbos pushing more power and quicker than your setup by a lot. One is kellys he's destroked with reverse manifold efr7670 and his hits powerband ~4K and rides that baby to redline 8k.

What are you using for boost control? Potential the wastegate is blowing open? I cannot understand how short your powerband is.

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I'm having my doubts about the turbo as well, my tuner has a Tial .63 exhaust housing that I am setting my eyes on. Just get hold of a up pipe w/ wastegate and that's probably my first attempt at coaxing this turbo to life earlier.

I am running a fuel called "Podium" over here, premium pump fuel, supposed to be pretty decent, 98 octane in theory.

I'm gonna check out those turbos, thanks!

I am running a Grimmspeed Boost Control Solenoid, braided lines.

That seems to be in order, boost is maintained throughout, I've looked alot at the gauges in various conditions. It only pulls once the wastegate opens tho. My first car with fmic and a first with this turbo, so, I don't have much of a reference.

I guess stretching the limit to 8k would also help, but, I wasn't really planning on fiddling with that because of reliability.

Thanks for the input!
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Old 08-02-2014, 12:10 AM   #10
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Are the exhaust elbows ported? Didn't are that on the list or missed it

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Old 08-02-2014, 12:13 AM   #11
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Any way of telling what those wastegate cycles are. The power delivery is very linear a lot like the wastegate never actually stays fully closed. Could also be those huge cams, tho I'm skeptical that's the root.

Killer b has got quite a bit of impressive results with the trial hotside I'd try that out!

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Old 08-02-2014, 12:51 AM   #12
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Are the exhaust elbows ported? Didn't are that on the list or missed it

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No porting was done on the exhaust. Its all invidia except for the exhaust manifold that is oem with a Grimmspeed cross pipe. I really want a Killer B so I haven't bought a very good one for half the price, but, it's a lot of money and import tax is even worst. Kind of in a corner on that one.

thanks!
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Old 08-02-2014, 12:58 AM   #13
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Quote:
Originally Posted by Razgeiz View Post
Any way of telling what those wastegate cycles are. The power delivery is very linear a lot like the wastegate never actually stays fully closed. Could also be those huge cams, tho I'm skeptical that's the root.

Killer b has got quite a bit of impressive results with the trial hotside I'd try that out!

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I'll check with my tuner about the wg cycles

All throught the laggy section of the rpm range it is fully closed (0 - 4700+-) after that its fully open and I hit the limiter very fast on the lower gears.

I'll definitely check out the housing, really like their products. Thanks!
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Old 08-02-2014, 05:12 PM   #14
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Quote:
Originally Posted by Speed Addict View Post
No porting was done on the exhaust. Its all invidia except for the exhaust manifold that is oem with a Grimmspeed cross pipe. I really want a Killer B so I haven't bought a very good one for half the price, but, it's a lot of money and import tax is even worst. Kind of in a corner on that one.

thanks!
You are killing your spool with not having your elbows ported. The cross pipe is a larger diameter than the elbows and will cause slow spool and reversion

Get the stock cross pipe back on or port the elbows

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Old 08-02-2014, 09:08 PM   #15
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I would replace the exhaust manifold with a FullRace or KillerB setup. That will help spool. As others have said smaller cams would make a large difference as well.
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Old 08-02-2014, 10:05 PM   #16
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I would replace the exhaust manifold with a FullRace or KillerB setup. That will help spool. As others have said smaller cams would make a large difference as well.
Quote:
Originally Posted by wrxsubiemod View Post
You are killing your spool with not having your elbows ported. The cross pipe is a larger diameter than the elbows and will cause slow spool and reversion

Get the stock cross pipe back on or port the elbows

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I guess getting some variables out of the way is key, establish priorities and go from there.

I got a good deal on a brand new Tial .63 housing right here in Sao Paulo with my tuner, bought it this afternoon. Got lucky on that one.

I'm almost certain on getting Perrin big tube headers, I feel like I cut a corner with that crosspipe. I've only seen pictures but it appears that it will be fine with the KillerB oil pan. Can someone confirm this? A GS Ceramic coated Up Pipe w/ 44mm EWG is also the probable choice.

After I get this stuff together I'll update the thread, hopefully get it reflashed and to the dyno again soon.

Thanks a lot for the input!
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Old 08-02-2014, 10:13 PM   #17
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Big tube header won't help with spool faster most likely.

If you got the coin the killer b header is what u want
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Old 08-03-2014, 12:47 AM   #18
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Big tube header won't help with spool faster most likely.

If you got the coin the killer b header is what u want

The point is the system needs a minimal back pressure?



I really like their products, but, I have so much more stuff I still need to buy to get all the "sections" of the car on the same level as the engine, as it is right now.

Suspension, wheels, aero, cooling, etc. I guess its the same story with everyone, just gotta make some choices.

I guess I am still open to a Killer B header, but it just has to make sense. At this point, to me, it wouldn't make sense to "pay double" for much better alloy, but, on the other hand, apparently the design performs and is outright awesome.

Asking in plain english, is the Killer B really worth considering its 2x the price of Invidia, Perrin and Tomei, give or take a few bucks?

Thanks!
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Old 08-03-2014, 09:31 AM   #19
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Big tube headers will definitely not help spool up. Think about it; a turbo exhaust manifold needs to be pressurized to spin the turbine and make boost. Adding volume (big tube headers) means it takes longer to build that pressure. Don't buy into reversion or scavenging theories with these systems. That is naturally aspirated technology applied to a turbo application and they are VERY different in design to a turbo manifold. There are books on this and I highly recommend anyone interested in learning about the difference to go hit their local library or Barnes & Noble.

Changing to a smaller A/R housing on that turbo will not net you fantastic results. The 3076 is better matched with the mid or large turbine housing, not the 0.63. You'd likely get a bit less power but MUCH better spool up characteristics and low end by going to the GTX3071 with the 0.82 A/R housing. Then again, if you're using an ATP style OEM housing you're kinda stuck with few choices, unlike using the Tial housings.

The ATP housings are very convenient as they are a bolt in product, but the housings are still based on the OEM housing design, which without a doubt reduces turbine performance. An EWG version definitely induces turbulence into the volute, which is not good. Moving the WG further from the turbine and using a performance designed housing (Tial for example) will net you some decent improvements.

Changing to the smaller MV-S (38mm) wastegate will give better modulation of boost and less of the uncontrollable surge of torque that is causing you to loose grip. The smaller gate can allow it to crack a bit sooner assisting some with spool as well. You're not running low boost pressures so the 44mm is not needed. In fact, we NEVER use a 44mm on these cars, it really doesn't make any sense unless you're running 12psi of boost.

Another option is you run some fuel with more bang to it. C16 and especially E85 would widen that curve quite a bit AND make more power.

I can't answer if the Killer B Motorsport header is the right header for you. Everyone has their own reasons for what their wants, needs, and goals are. I can tell you it makes more power than anything else currently available. Or at least we've not come across anything else that makes more power (and there are LOTS of plots not floating around out there), and using titanium alloyed stainless steel (321) certainly has it's benefits as well as a hefty cost of admission. Unfortunately, there's nothing we can do about the costs, it is what it is. The justification of the product, or any product for that matter, is what it's worth to you (performance, durability, etc.) by having it. For some it's worth every penny, and for others it's not as important.
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Old 08-03-2014, 02:49 PM   #20
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Originally Posted by KillerBMotorsport View Post
Big tube headers will definitely not help spool up. Think about it; a turbo exhaust manifold needs to be pressurized to spin the turbine and make boost. Adding volume (big tube headers) means it takes longer to build that pressure. Don't buy into reversion or scavenging theories with these systems. That is naturally aspirated technology applied to a turbo application and they are VERY different in design to a turbo manifold. There are books on this and I highly recommend anyone interested in learning about the difference to go hit their local library or Barnes & Noble.

Changing to a smaller A/R housing on that turbo will not net you fantastic results. The 3076 is better matched with the mid or large turbine housing, not the 0.63. You'd likely get a bit less power but MUCH better spool up characteristics and low end by going to the GTX3071 with the 0.82 A/R housing. Then again, if you're using an ATP style OEM housing you're kinda stuck with few choices, unlike using the Tial housings.

The ATP housings are very convenient as they are a bolt in product, but the housings are still based on the OEM housing design, which without a doubt reduces turbine performance. An EWG version definitely induces turbulence into the volute, which is not good. Moving the WG further from the turbine and using a performance designed housing (Tial for example) will net you some decent improvements.

Changing to the smaller MV-S (38mm) wastegate will give better modulation of boost and less of the uncontrollable surge of torque that is causing you to loose grip. The smaller gate can allow it to crack a bit sooner assisting some with spool as well. You're not running low boost pressures so the 44mm is not needed. In fact, we NEVER use a 44mm on these cars, it really doesn't make any sense unless you're running 12psi of boost.

Another option is you run some fuel with more bang to it. C16 and especially E85 would widen that curve quite a bit AND make more power.

I can't answer if the Killer B Motorsport header is the right header for you. Everyone has their own reasons for what their wants, needs, and goals are. I can tell you it makes more power than anything else currently available. Or at least we've not come across anything else that makes more power (and there are LOTS of plots not floating around out there), and using titanium alloyed stainless steel (321) certainly has it's benefits as well as a hefty cost of admission. Unfortunately, there's nothing we can do about the costs, it is what it is. The justification of the product, or any product for that matter, is what it's worth to you (performance, durability, etc.) by having it. For some it's worth every penny, and for others it's not as important.
Thanks for the help!

It makes perfect sense that less volume is better in this case.

I'm not sure of the size of the standard location ATP housing, but, considering the current laggy curve, I have a feeling switching to the tial won't have any drawbacks. It was a real bargain, so, that had a lot to do with the .63 size to be honest. But it's good to know I can always upgrade later. The same with the 38mm wastegate, I'm going to stick to my 44mm for now to save up for the headers.

Better fuel is hard to come by, unfortunately. I've had cars converted to run on "our e85" and eventually they all had erratic clogging of fluid lines, filters and pump on cars that were originally running petrol. Never found out what caused it, I just steer clear now.

I guess I'm pretty much sold on the Killer B headers and up pipe, buying another brand will feel too much like cutting a corner right now. Congratulations on the very original design and performance!

Thanks!
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Old 08-03-2014, 02:56 PM   #21
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Maybe a better tune?
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Old 08-03-2014, 03:35 PM   #22
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Thanks for the kind words!

IIRC the ATP housing is 0.74 A/R.

The quality of E85 is hit/miss no matter where you are. Any car considering it should run an applicable 5-10 micron filter. That will take car of any debris in the fuel and E85 has a lot. Anything smaller than 35 micron should pass through the injectors, but it can scour the internals. So a good filter is important to running a reliable E85 setup.
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Old 08-03-2014, 10:22 PM   #23
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Another cheap option would be to try a good Electronic boost controller, like old school Greedy Profec. In theory they keep the wastegates' mechanical springs completely unloaded until targeted boost.

The theory is that the wastegate springs are linear, they could start to open before the desired boost is reached. This could be your case. I had a GTX3582 (much laggier turbo) that doesn't drive as bad as you're describing..

I've seen this reduce "lag" drastically back in the days with old school HKS ext wastegates. could be worth a shot...
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Old 08-04-2014, 08:40 AM   #24
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If I remember correctly (and I am no tuner by any means) most are doing something like this already via the ProTune, to promote spool.
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Old 08-04-2014, 11:27 AM   #25
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Its called "Wastegate Duty Cycle"...
Less WGDC = Less gasses bypassing the turbine = better spool up

However with modern EWG the wg springs should not open prior to boost pressure exceeding spring pressure UNLESS you are using controlling boost via an EBCS.

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