Sanzomat
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| posted on 30/7/26 at 04:20 PM |
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Higher flowing injectors for R1 5PW
Hi All,
Just thought I'd post on this in case it is useful to anyone else (wasn't sure if here or BEC though but went for here!)
About 5 years ago my R1 engine Locost (4XV engine with respaced 5PW throttle bodies for injection, Speeduino ECU) was mapped and whilst a decent map
was built up the tuner commented that the injectors were running out of flow, reaching 100% duty cycle just past 11k rpm. We set the limiter to 11k as
above that it would start to go lean. He said the injectors don't like running at such high duty cycles and can overheat and fail prematurely so
advised getting higher flowing injectors and re-mapping. They were standard R1 5PW injectors - 210cc/min.
Following advice from on here I bought a set of used 320cc/min injectors from a nice chap by the handle of Hobbsy. I then baulked at the cost of
another rolling road session so soon and as the car was working great I used it for five years.
The last two track days I've been having a top end misfire such that it wasn't getting even to the 11k rev limit, barely getting over 10k. I
suspected the injectors were finally dying so fitted the ones I'd bought 4.5 years ago! I changed the fuel constant by the ratio of new flow rate
to old flow rate and it started and ran fine with no load but thought I'd better invest in a rolling road session to make sure it was fuelling
right before the next track day.
On the rollers we found it was lean low down but getting overly rich at high rpm so the fuel map was adjusted. The power runs showed a 10bhp gain from
5 years ago now at 10,800 rather than previously at 10,400 and the injectors never went over 75% duty so we set the limiter to 11,500 now (I believe
on the bike its set at 11,800 but wanted to keep a bit of spare). Its on a different dyno so the difference might not be real though but the ability
not to run out of injector flow is definitely real.
For anyone interested, the higher flowing injectors are from a Mitsubishi Galant 3.9 V6 and they are physically identical to the R1 5PW ones other
than having 12 injection holes rather than 4 so an easy direct swap - who'd have thought!
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JAG
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| posted on 31/7/26 at 09:56 AM |
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That's good to hear 
I remember our original discussion about the flow rate change (210 to 320cc) and doing a simple scale of the original map via the 'fuel
constant'
It sounds like it was pretty close and just needed a tweak here and there (which is always where the experts excel!)
Time to get out and drive   
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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