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I need serious help with turbo/tune setup.

Old 03-09-10, 12:10 AM
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I need serious help with turbo/tune setup.

There are so many out there and so many successful setups that i'm not really sure what i want and the more i read and look into stuff the more confused i am.

I have an s4 na btw. There are guys that na-t their motor with a stock hitachi ht18 and all the stock s4 TII stuff or S5 or whatever.


That was my original idea since piston swapping will not be happening with this car.

I did some digging into the stock turbo. It turns into a hair dryer at high boost and pressure falls off in the upper rpm range.

Why is that? Pre-turbine backpressure and LOTS of it. The thing is too small to keep up. Aside from the hotside not being very efficient and internal gates causing creep i opted to go with something a bit larger. BNR hybrids were out of the question because i feel the hotside is STILL too small to keep exhaust flowing freely. Yes, the wheel can be clipped but why bother?


My goals are 300-350hp. That's what i want. Yes, i can be happy with 250 but it's pushing the stock turbo to it's limits and the n/a route just isn't for me unless i put a 20b in and i'm not doing that.


My options currently were running 8-10psi on a gt3582 non ball bearing t3 (keep in mind is a high comp engine) or a holset hx35 with a 16cm housing.

Does anybody see there being a problem with running turbos like that only shooting for mid level power? I'm after super fast RESPONSE primarily but i dont want to choke the exhaust flow with a tiny hotside and i also do not want to port the motor any time soon. If i get a few spare blocks, that is subject to change but only to an extended port/street port. Nothing extreme or out of the ordinary for a street car.


I have no idea what injector combination would be best but my gut tells me 680/1000 might be fine from the research i've been doing. I'm not really sure though (that's why this thread is here for me to learn and get input. ) Aux injection IS going on the car. I feel it's almost necessary on a turbo rotary running pump gas and especially my high compression motor.



Last but not least, management. I wanted something easy to tune and easy to make power with. My first thought was rtek since it's just a simple "send your ecu off, get it back and stick your pda into it and have at it", you know, like a russian mail order bride...... Then i read 300hp was achievable with the unit but it takes a good bit of work and the record is 350-ish hp. For what i want to do that system would be near it's limit. I want a comfort bubble.

Power fc and commander + banzai racing stuffs to get it to work with my s4 seems to fit the bill and should be able to handle what i want to do pretty easy.



Just tell me what you think, ask questions, w/e because i dont want to waste money or put things on my engine only to have my car sit for another year because i can't get it to run. Trying to get as much feedback/research out of the way as i can before i start spending money.

thanks.
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Old 03-09-10, 10:37 AM
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This is my opinion and only that...(putting on my flame suit)

Turbo:

Your goals can be had with a T3/T4 hybrid. T40E cars locally have been dynoing around your ideal HP goals.

The complete exhaust system has been thrown out the window and replaced with a turbo header of your choice and T40E with internal wastegate. If you want to get fancy, you can opt for the external wastegate but for a street car, it may be more work than its worth.

Fueling:

I use this as a comparison when talking about injectors. On my race team, we have a bone stock 13b in a FB. It runs 550's and 1000's. On the dyno, it can't maintain a 13.5 AFR. It leans big time especially at the 2nd stage 3500rpm sweetspot. My recommendation is use 850's and 1200's. 350hp=~3500cc of fuel (*ish* for turbo engines) 1700cc primaries with 2400cc's secondaries gives (carry the 4) 4100cc of fuel to run the HI-comp engine FAT on fuel (keep your AFR's in the 11-12 range).

Which brings me to...tuning:

I like running megasquirt. Why? it's decently priced, has decent support and has good parameters for expandability. I like that you don't need (or cant use) the AFM or the 20yr old sensors that sometimes plague the community in regards to tuning. Keeping your engine happy is a combination of good fuel, good fuel ratio's, keeping your charge air as cool as possible and proper timing. As the engine is High Comp. it will be harder and more finicky to get it right. But it can and has been done. A good wideband will aid you in your quest.

Good luck.
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Old 03-10-10, 01:15 AM
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You're free from being flammed. This is a help thread, not talk **** on people's setups thread.

Seems like alot of the fd guys running single gt3582's love them. Good response, great peak boost.

Wideband, egt and boost gauge are a minimum for any turbo car that is to be modified or have the boost upped i feel. Going with a jaw unit because they're inexpensive and the lcd readout is nice. EGT and boost could be anything from a reputible company like defi, hks, autometer......

Also, that is ALOT of fuel for up to 350hp but your resume in your sig says i can trust that suggestion and i will look into it further.

I'm a bit intimidated by megasquirt which is why i was trying to get into the power fc and commander but i will look into it more as well, see what others have done. I know guys in the 400hp range on tII motors are running quad 1000's or 1000cc primary with 1600cc secondaries if not bigger.

Kinda curious to what the duty cycle on the injectors would be at to have ideal afr's with the 850/1200cc combo......

Anyway, thanks and i'll painstakingly look into your advice to see what others have done on those injector sizes and what they're tuning with. Do you think a single walbro 255 will be up to the task to push that much fuel?

Anyone else care to comment/help?
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Old 03-10-10, 03:03 PM
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Browsing the specs available online, GT3582 seems to be an acceptable "streetable" turbo keeping the a/r in the .7 range. In theory, there should be little lag with that setup.

On my race port engine, I am running a 1.05 a/r and it should spool around 4k. A local car, runs a cummins turbo with 1200 primaries and 1600 secondaries. The car does run a bit piggish, but the end result is that you shouldn't get a lean condition. I would prefer to shoot fuel out the exhaust than a vital engine component!

I've got one megasquirt going now and it's not as bad as it seems. I would hazard to guess I am a little faster than the average joe as I have done plenty of small electrical projects in my younger years so reading schematics isn't really an issue. Using the step by step assembly guide, it make things fairly simple!
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