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Author Topic: Choosing base tune 2.5 m20  (Read 4121 times)


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Choosing base tune 2.5 m20
« on: December 09, 2013, 05:16:16 PM »

I just received my PSIK and war chip. I'm trying to pick a base tune to start with and was wondering if anyone out there has a tune for an engine similar to mine. I just rebuilt my 2.5 m20 engine with:
stock pistons
Bimmerheads ported head
Bimmerheads 274 cam
Slightly ported I manifold ( intake runners opened up to match ported head)
Larger throttle body (M20 I throttle body bored out, can't remember exact size but I'll get that info later)
I.E. heavy duty rockers
I.E. crank scraper
Stahl long tube headers, Magna Flow High flow cat, single 2.5" pipe to a Perf. muffler
Miller PSIK 3" MAF kit/ stock injectors
That's about all I can think of for the internals. I just installed a AEM wide band I also purchased from Miller so I can keep an eye on things. I'm looking for a good performance base tune and also a decent economy tune for those days I'm in traffic and can't really enjoy the performance mods. I see in the tune cache there are a couple tunes to start with, but nothing with the PSIK and stock injectors besides a stock tune. I'm just wondering if anyone has a head and cam like mine and has started modifying their starting points. I'll be headed to the dyno here in Elsmere at E.R.T. at some point to really get some decent results.
« Last Edit: December 09, 2013, 05:38:21 PM by bmwstudent »


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Re: Choosing base tune 2.5 m20
« Reply #1 on: December 11, 2013, 05:30:29 PM »

I've noticed that there are a couple tunes in the cache for a slightly modified engine but with 19lb injectors. I was wondering if it would be a good idea to go ahead and replace the 14lb injectors and try one of those tunes setup for an m20 with the psik, headers, HFE, and 19lb injectors. Anyone have an opinion on wether my 14lb'ers would be maxed out with the mods I've made or are they still sufficient?


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Re: Choosing base tune 2.5 m20
« Reply #2 on: December 12, 2013, 06:47:39 PM »

Upgrading to 19# injectors will definitely benefit you. The 14's MAY cope with it, but you'd be safer and better off to use 19's.

The most important part about a tune is the air flow table being calibrated for the MAF/AFM that you are using along with matching the calibration for the injectors being used with given AFM or MAF. The 19# HFE headers tune would be the tune we would start with on your car if you brought it to us for an in person custom tune. Being calibrated for the PSIK and 19# injectors is about 90% of the puzzle. The cam will make a bit of difference that is easily tuned out if tuning becomes needed.

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Re: Choosing base tune 2.5 m20
« Reply #3 on: December 12, 2013, 06:55:40 PM »

Thanks for the response. I haven't installed the PSIK yet but hope to do so soon. It looks like I should go ahead and source some 19lb injectors. When I do I'll start with the 19lb header tune and go from there. I'll be going to a local dyno here in De. (E.R.T. in Elsmere ,DE.) and will post results when I have them.