478 with Dual Exhaust

[who_gives_a6]

I know someone has a setup like this around. Have been trying a lot of combos but having issues with it and numbers don't seem right so looking for input. Too late right now to keep trying due to neighbors.

460 piston, stroker crank, timbo ported head and throttle body, cyclone pod intake, FMF dual exhaust, 108/106 cam timing, gutted disconnects, and I'm probably still forgetting something. I built it to pump out a LOT of power in the mid to upper rpm range.

Currently running the Trinium map at 1600 flow rate and .90 offset.
It starts and runs flawlessly. Barely a turn of the starter to roar up. It has some popping on decel. I have messed around and this was the best setup so far but seeing what others may have done. Carbs are easy. Still learning this FI stuff even after 4yrs of these things. A dyno run isn't doable at the moment either.

[SlOoT]

Wasn't the trinium map made for a 448cc?

I think the terminator map (467cc) or exterminator2 map (495cc) will be closer to your setup.
But the exterminator2 was made for harley injectors.

If you can't find the maps, I have them on my pc and can post them if you like.

[who_gives_a6]

Alright, at current settings in backfires on decel but idles great. I raised the offset a little and when I gave it throttle it kept dumping fuel after letting off the throttle but the backfiring decreased. Takes a second to bring it back to idle. So I put the offset back to .9 where it liked it and the throttle is right again.

It seems to be running pretty hot too which makes me think lean of course. But nothing seems to cure it. When I lower the flow rate it decreases backfiring but I can't recall ever seeing flow rate numbers in the in the 1400-1500 range from anyone on here.

Am I missing something or should the numbers not matter if it's running great?
Just wanna finish it and get it out riding.

[SlOoT]

I think you need to change the map, the one you have now sounds like it is to lean.

[wistech]

This might sound like a silly question but what flowrate injectors are you using?

[who_gives_a6]

Brand new stock injectors. Not sure what they're rated at or if they varied.

It runs flawless at 1475 flow rate and .92 offset. Starts fast, no backfiring, and no longer running hot. Plan to dyno it when possible but not now. Will have it assembled and ready to ride by the weekend for a full test.

I have the exact same setup on another except it's a single HMF and has a 97mm piston instead of 98mm. It runs 1750 flow rate and .88 offset with a smooth AFR on dyno. Just seems strange that it'd be that different with a 10cc difference.

[riverat1540]

We're you able to figure it out? I'm building almost the same setup and was wondering if you had to go larger injectors.

[wistech]

A 460 with a ported head is my limit before stepping to larger injectors. If the flowrate is below 2000 thats a good sign the stockers are maxxed out.

[who_gives_a6]

After taking out the injectors and soaking in cleaner/blowing them out, replacing the hose in the tank, and cleaning the screen on the hose, I ended up with a 1600 flow rate and .92 offset. Starts well cold and barely even a turn of the starter when hot to roar to life. Zero backfiring or hot running issues and the plug is a light brown color. Fuel system is fully opened up and gutted. I think the tank hose/screen was the lean issue. Was gummed up pretty good. Strangely enough there's a fresh post about that.

With this setup the power is ridiculous but really shines in the upper rpm's. I matched it with a motard 5th gear and it pulls 5th like it's nothing. Running 15/40 sprockets on 18" rears to give you a few ideas of performance. It never goes below 3rd gear after takeoff.

[who_gives_a6]

FYI: running the dual exhaust fades the rear shock FAST. I ended up putting header wrap on the headers to cure the issue and seems to have worked.