Turbo Kits: Rational boost threshold yet?
 

I just spent a while looking at every single turbo kit listed in the Compilation sticky thread, and from what I can see, none of them are designed for satisfying street application. Most if not all of them have a 4K RPM+ boost threshold, and that's not acceptable for daily driving behavior.

Do any turbo kit manufacturers have plans for a reasonably sized turbo, or are there kits in the pipeline done by veterans with their heads on level that actually want to drive the car?

Mandatory criteria:

*<2,500 RPM boost threshold. I want to be able to cruise at 60 MPH in 6th and get real torque in a timely manner for effortless passing.

*Attention paid to thermal management. Too many kits out there are haphazardly ignoring a 1200°F chunk of iron glowing inches from serpentine belts, coolant hoses, radiator shrouds, and suspension components. PLEASE people, the OEM's use heat shields for a reason.

*Power? I'm not 8 years old anymore with a Lamborghini Countach poster on my bedroom wall. In the real world of on-ramps and Interstate passing and stop-n-go, I want a big fat wide torque shelf. If the turbo isn't tapped out on compressor flow by redline, it's too big and giving up low-end torque. Think BMW N55, not Evo VIII.

*Turbo kits with reckless disregard for reliability will be openly dissed. Obviously very few people have access to E-85 on a daily basis; design the kit for 91 octane, and that means rational boost levels. Again, I'm looking for broad torque, not dyno queen peak HP.


Since AVO & Accelerated appear to be the biggest player so far in the turbo kit arena, I'll put out an open invite to them: Build a Stage 0.5 turbo kit with a GT2560R or GT2854R and associated ECU tune for the folks that want maximum low-end torque.

:thanks:

The stumbling block for this engine is the compression ratio with boost.

If you want instant torque buy a twin screw kit, these turbo kits are fine.

This.


Plus most turbos that come on at the 2k mark on an engine of this displacement size tend to run out of steam very quickly. Nothing is worse than having a turbo go asthmatic on you at 5k when you have more room to stretch your legs. I personally feel that the kits being designed have in mind the fact that the driving characteristics of this car compliment peak power within the ranges of 4k-7k rpm, making passing power at 6th gear an afterthought.

Also, the amount of heat generated for the power levels you are looking for wont come close to melting belts, furthermore the position of those turbos are in the direct path of ambient airflow making a shield almost negligible.

I agree with you on the E85/93 statement though. Not much love for us Californians.

You should look a little at crawfords build. The price is crawford high, but the torque curve will give you wet dreams.

Sent from mission control

Most of the kits I've seen don't really spool all that late. You are probably hitting 2-3 PSI by 3000 RPM unless you are going for big power with a larger turbo. The FBM kit just posted makes more torque at 3000 RPM than the stock car does anywhere in its entire powerband. Same goes for the AVO kit, the Accelerated BRZ-300 kit. In the real world the car will often make boost sooner than on a dyno due to load differences as well.

The Crawford kit uses a fairly small twin-scroll turbo and makes a ton of low end torque. I would say almost too much, I could see the car being a handful to drive. It indeed has a turbo which dies off by redline.

Just for reference, have you ever driven a turbocharged car with a 2.0L 4 banger? 4k rpm is actually pretty damn amazing for a little high revving 4, and will definitely be satisfying for a street environment. People have already mentioned that you can get the boost to come one earlier with smaller turbos, but you run the risk of the turbo not being able to produce power to redline...and that sucks. The turbo's in the provided kits are all pretty much as close to perfect for a bolt on application as you can get, they spool up quickly, provide power throughout the RPM band and fit under the hood.

As for daily driving behavior...dunno bout you but im 32 and find myself ripping to redline as often as possible in my stock engine FRS...that's where the balls of this car are stock from 4500-7200rpm, slap a turbo on and nothing changes with how you should be driving it as it was actually designed, well except for how fast you end up changing gears and reach your desired speed...

Quote:

Mandatory criteria:

I hit this in my earlier paragraph. If you want that kind of response, and it's that important to you, there are people dropping LSx engines in this car. Someone may figure a way out, but without cracking the case open and swapping pistons, connecting rods, etc. you won't be seeing anything soon.

First off, where would you put a turbo in the engine bay that wont have some kind of adverse effect on what you just stated above? There arent many options available, so the kit builders do what they can by ceramic coating the bell housings and providing insulator blankets for the turbo...it's not perfect but what else can you do realistically. If it's that big of a concern, go SC instead...no heat there!

BMW N55 eh...turbocharged 3.0 Straight-6. FA20 Turbo, 2.0L boxer 4, you do realize the Straight 6 is a torque monster, while the Boxer 4 isn't widely know as a great producer of huge torque. HUUUGE difference here, small displacement 4 cylinder engines are by design peaky, the boxer 4 is the best design for producing bottom end torque, but it's not gonna win any stump pulling contests, even with FI. Once again SC may be what you are looking for, since it has a flatter torque curve.

This is the best line, you claim to have been paying attention to the turbo builds going on but don't know that all the kits pretty much come with a base tune utilizing EcuTek (or in some cases a piggyback) for pump gas. They don't come with 20PSI, 440HP maps for E-85, because that requires you to take your car to a dyno and have it tuned for your application. I know that my P&L Motorsports kit comes with a base 5PSI tune just to get the car running on 91 or 93 octane...it's not a tune you keep it will be a little rough, because no two cars are exactly alike. So basically you pick a kit, and have it tuned to your needs, want to run 91 octane, you'll probably be sitting at about 8 PSI max reliable boost. You can also buy multiple tunes, and now that EcuTek is working on a true FlexFuel offering the possibilities are endless.


I'm pretty sure you can call one of these shops and they can throw your ideal turbo on a kit with the proper fittings it never hurts to ask!

^Hes right, I drive a turbocharged vw jetta and while the turbo is small and I can have full boost by 2.5-3k. It really shows its weakness in the high rpms because it loses alot of pressure. IMO you should get something along the 4k threshold because A. Youll save more gas around town (since the turbo isnt kicking on so early) and B. Youll have the power in the later rpms where it makes the most difference.

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I would not call what your looking for a street application I would call it an autox setup. Your overall gains will also be much lower as well. 3-4.5 is just fine for boost threshold on a street app. If you think its not then your are in the wrong gear in a higher revving engine.

E85 may not be available to all but for those it isn't you are missing out. I love being able to go to the pump to fill up and be able to run race gas equivalent boost pressure without 93 octane worries, water injection or cost of race gas. Otherwise I would be stuck in the 400 whp range instead of over 500 on the street in my 7. :-)

Its a shame MHI stopped producing the 16g's, that would solve OP's issue's, good spool, reliable, small size for easy packaging and limited heat along with 3xxwhp threshold.

/thread.

what your asking isn't friendly on this motor. it's a high revving motor. it's going to utilize the 3k and up RPM much better. what's wrong with downshifting to 5th and accelerating, getting the most out of your setup? most 6th gear pulls like you speak of, lead to high EGTs, boost spikes, and sloppiness. you're basically asking for a 2.5L sti motor in the car with a 20g or a vf39 all decked out. this is not a torquey motor, as it's brethren are.

i'd rather have this motor perform at 3k and up. while cruising, you don't want to be in boost for MPG reasons. we have 6 gears, play with them.

If I were looking for a supercharger setup, I'd want a TVS as it has excellent adiabatic efficiency and doesn't lose fuel economy versus a twin-screw, but nobody's developed one yet for this car. Nevertheless, that doesn't address my question of a low/mid RPM turbo kit. I understand big peak HP numbers impress, but I'm not looking for that. If anyone has driven a current BMW 328i, Cadillac ATS 2.0T, or VW Golf R, those are reasonable examples of the torque curve I'm interested in.


:word:

K03 or 4 should do the job. Maybe not as robust as the 16g, but they should work.

Basically, OP is looking for Subaru to offer the new turbo 2.0 liter engine in this car

http://www.subaru.jp/legacy/dit/perf...ges/pict02.gif