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Street Tuning NA Motors


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Hi all,

I have followed this forum for nearly a couple years now and finally thought I'd post something as I'm sure there are plenty doing something similar to what I have. Before I start, it has been pretty bloody awesome being able to build and tune my first car from my garage, literally. There are some really informative post on here, 90% of which I've read in close detail and this has enabled me to undertake the iconic NA to Turbo conversion on my BF XR6. As of now I've retained the NA computer and swapped a BA turbo motor into the car and have been running 10psi on 98 with an NA ION box for the past 3 months without any dramas. I've invested in a wideband and Tuner Nerd knock monitor to assist with tuning on the street as best as I can. Getting a solid pull on the street without spin has been quite difficult so I am sure I have some room to improve but as of now fueling is on point and I'm very confident there is no knock on a full heat soak in this weather. I'll be getting rid of the Turbo motor and running a $400 BA NA motor to see what it's capable of on E85, but mainly it will be set up to daily 98 @ around 7psi. I'll probably just be doing valve springs and pump gears for now as I've seen quite a few people running high 10's and even low 20 psi without even removing the head (stock head bolts and gasket). I'm sure this should be fine as I doubt I'll push any more than 12-14psi. So, my questions for people who have done similar out there, what sort of power figures are people running on NA motors, in particular the BA's (weaker rods but lower compression). I understand there are differences throughout models (BA 9.7:1 and BF-FG 10.3:1 comp, cam lifts, etc), but correct me if I'm wrong, the BA NA and Turbos have the same rods, which is a common fail point from what I understand. I think my plan of attack will be more conservative timing in lower rpm where boost comes on, just to dampen that peak torque spike I'm sure we are all familiar with. I think running stock tyres for a bit of slip through peak torque should minimise the stress on the rods too. Cheers!

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I have a ba na motor, with only valvesprings upgrade.. on e85 with a 3582 on 12psi makes 401Hp. this was tuned by a workshop. ive thrashed it for the last ~ 4-5 years now and it refuses to die.


i have a bf na motor with a china gt45 running 98ron with water meth injection and no intercooler. we sit that in the burnout pad and let it eat and its been like that over a year  now. no idea on HP as its was street tuned by myself.

I ran it on 14 psi for a pull and you could smell coolant.. you might want to think about head-bolts if your going to try run 20psi.

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  • 1 month later...

Just goes to show you how tough and resilient a bone stock barra can be. I just finished up on the NA conversion. Just a note for anyone else doing this on a stock setup, retarding large amounts of timing and enriching fuel for inital safety will result in difficult to control boost on the standard internal wastegate. Whilst this is unlikely to knock on safe timing it can cause huge boost spikes and creep so just something to be aware of. I ditched the small internal gate and fabricated a 90 degree 50mm steam pipe bend onto a spare housing with an external gate and screamer. As of now, I have the car on 8psi. Ive mad adjustments to speed density tables to get my commanded and actual pretty well perfect (stock injectors make this easy). I've started adding timing in certain areas. Over numerous small advancements from my initial safe timing the difference is quite significant from what it started with, both with how the car pulls and the actual timing numbers themselves, I just wanted to start safe as this is my first timing tuning and I don't have any data for reference. I've verified all changes with the tuner nerd knock monitor and on a good heatsoak to monitor any knock too. 

I'm putting together a greentop FG motor that I picked up for $350 too so hopefully that will be tuned on all 4's when I find a good gq patrol shell to run it in with a zf behind. As for now I'm doing my own custom studs and gears with backing plate, a set of springs and ACL race series big end and mains. 

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Little update on the NA + T setup. Speed density has required some work (50mm screamer and cat-less otherwise stock) and now fueling looks really good, commanded and actual are almost identical everywhere. Since then I've started to add timing and leaned out fuel on the base table as for safety I had it quite rich in load areas to start with. As for timing I've added a few degrees to aid in response under boost and some timing in the top end after peak load hits. The current result is a pretty well responsive, knock-free fun drive every time. Have done at least 50 2nd gear pulls over the past few days (remote straight open roads) and has not skipped a beat. For being fresh off my P-plates this really feels like quite an achievement. I've chucked a small list below of what the cars supporting mods are/setup for anyone in a similar boat. Should get a power figure soon once it hits a dyno for a touch up on spark and a power run.


BF NA Motor from a Territory with 120,000km in 08 xr6 with 4spd ion

- Custom billet OPG and plate

- Empire elite timing chain

- Stock springs

- Factory B series manifold

- 1000hp Plazmaman IC and 3' piping kit

- 4' CAI and custom Battery relocation

- Custom fabricated 50mm external gate w/ screamer off rear housing

- Factory dump center muffler and rear muffler with cat smashed

- Transcooler and thermofan on switch

- S5 solenoid mod

- 255 walbro intank

- Turbo 4 bar FPR

- Turbo TMAP


Tuning Equipment

Tuner Nerd V3 Knock Detection

AEM wideband running analog output via DLP in PCMtec (Digikey supported)



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