Looking for injector recommendation.
Thread Starter
Teching In
Joined: Nov 2015
Posts: 25
Likes: 1
Looking for injector recommendation. I have an HKE built LS3 427 stroker in a 2800 lb RX7.
I installed a Megasquirt MS3Pro with their drop-on harness.
Currently have a ported LS3 intake with cable TB, JTR 1-7/8 Longtubes, with 3" X-pipe and duals. Injectors are LS3 42#/hr.
Got it dynoed last week and it only made 525rwhp. I was expecting a bit more, and when I got it on the road it is WAY DOWN on power and throttle response from when it had the tuned GM pcm.
I sold the GM pcm, so am unable to read the old tune.
If I had known earlier about the local dyno tuner, I'd have had it baselined before I did the swap.
Big problem though, is the injector duty cycle greatly exceeded 100% on the dyno, even though AFR's were good. It even hit slightly over 100% in street testing.
Obviously, I need to upgrade injectors before I go back for another tuning session, and would like suggestions on the best brand and size to use. Cost is a consideration, but not the only consideration.
Also, what are the largest injectors that would give a good idle and drivability with my combo?
I'd like a bit more headroom for when I later rebuild the motor, with more head work, and possibly a supercharger.
Thanks in advance,
David
I installed a Megasquirt MS3Pro with their drop-on harness.
Currently have a ported LS3 intake with cable TB, JTR 1-7/8 Longtubes, with 3" X-pipe and duals. Injectors are LS3 42#/hr.
Got it dynoed last week and it only made 525rwhp. I was expecting a bit more, and when I got it on the road it is WAY DOWN on power and throttle response from when it had the tuned GM pcm.
I sold the GM pcm, so am unable to read the old tune. If I had known earlier about the local dyno tuner, I'd have had it baselined before I did the swap.
Big problem though, is the injector duty cycle greatly exceeded 100% on the dyno, even though AFR's were good. It even hit slightly over 100% in street testing.
Obviously, I need to upgrade injectors before I go back for another tuning session, and would like suggestions on the best brand and size to use. Cost is a consideration, but not the only consideration.
Also, what are the largest injectors that would give a good idle and drivability with my combo?
I'd like a bit more headroom for when I later rebuild the motor, with more head work, and possibly a supercharger.
Thanks in advance,
David
TECH Fanatic
Joined: Aug 2009
Posts: 1,845
Likes: 255
From: Coast of San Mateo County Between Pacifica & HMB
I used 60 lb for my build, 690 FWHP NA, with plenty of room left over.
What's your peak RPM, you would benefit from FAST 102
With Mid-Length Runners over 6000 RPM with your LONG Stroke.
What's your peak RPM, you would benefit from FAST 102
With Mid-Length Runners over 6000 RPM with your LONG Stroke.
Ive used the FAST 57lb with plenty of room left on a 427 that made 600+. You would prob be maxing out a single 255 also. the ls9 injectors should get you all you need. they are 52# and all the inj data is out ther plus fit directly into ls3 intake and use ls3 uscar connectors.
TECH Fanatic
Joined: Aug 2009
Posts: 1,845
Likes: 255
From: Coast of San Mateo County Between Pacifica & HMB
I have been told by tuner that blower injectors have a different spray
Pattern and are not optimal for NA. A 450 LPH Wallbro pump
Would work ideal and have room for blower down the road.
Pattern and are not optimal for NA. A 450 LPH Wallbro pump
Would work ideal and have room for blower down the road.
I have a set of FIC modified LS3 injectors that flow 64 lb/hr at 4 bar as per the spec sheet they provided. I emailed them and they sent me injector data for them. I have not tried them yet. I will be making similar power as you and will max out my 42 lb LS3's.
I read the same thing about the ls9 injectors. I was pretty bummed.
I read the same thing about the ls9 injectors. I was pretty bummed.
Im prettt sure that may be correct in a few instances but not so with the ls9 inj. Usually spray pattern is offset for split port heads/intakes or iirc the 03-04 cobra fuel inj have a slightly diff pattern. Those are the only ones ive seen really.
Launching!
Joined: Jan 2008
Posts: 225
Likes: 1
From: Fargo, ND
Out of curiosity, was the crankshaft timing verified with a TDC mark and timing light? Engine timing out to lunch would kill power bigtime.
Lots of info on the Megasquirt/MS extra engine management owners group on facebook as well in case you arent there already.
I run Fuel Injector Development 850s (~1000cc@60psi) with my ms3pro and they have worked extremely well for me with dry nitrous application. Injector duty cycle is extremely low, allowing injector phasing for more power.
Lots of info on the Megasquirt/MS extra engine management owners group on facebook as well in case you arent there already.
I run Fuel Injector Development 850s (~1000cc@60psi) with my ms3pro and they have worked extremely well for me with dry nitrous application. Injector duty cycle is extremely low, allowing injector phasing for more power.
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Thread Starter
Teching In
Joined: Nov 2015
Posts: 25
Likes: 1
Out of curiosity, was the crankshaft timing verified with a TDC mark and timing light? Engine timing out to lunch would kill power bigtime.
Lots of info on the Megasquirt/MS extra engine management owners group on facebook as well in case you arent there already.
I run Fuel Injector Development 850s (~1000cc@60psi) with my ms3pro and they have worked extremely well for me with dry nitrous application. Injector duty cycle is extremely low, allowing injector phasing for more power.
Lots of info on the Megasquirt/MS extra engine management owners group on facebook as well in case you arent there already.
I run Fuel Injector Development 850s (~1000cc@60psi) with my ms3pro and they have worked extremely well for me with dry nitrous application. Injector duty cycle is extremely low, allowing injector phasing for more power.
I'm already on the MS forum, but thought there'd be more LS-specific experience here.
Thanks.
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