Big cam 304 Tuning help needed

[vlad01]

Indeed! I have a set of injectors put a side, I think they are the Bosch 968? And according to info listed on efihardware.com, they are a split spray at 20 odd deg overall pattern. I feel this is probably too wide for what I want, but it's certainly more narrow than other's I have seen, but not as narrow as my OEM ones or some of the Deka ones.

They might be fine, they might make things harder. But being split, they either suit 4 valve, or they might miss the valve stem and still land in the valve head/seat area either side which still sounds ideal in my mind.

[buzzard]

If that is the 0280155968, which I expect it is, that is the injector I used in the S50B30.

Indeed! I have a set of injectors put a side, I think they are the Bosch 968? And according to info listed on efihardware.com, they are a split spray at 20 odd deg overall pattern. I feel this is probably too wide for what I want, but it's certainly more narrow than other's I have seen, but not as narrow as my OEM ones or some of the Deka ones.

They might be fine, they might make things harder. But being split, they either suit 4 valve, or they might miss the valve stem and still land in the valve head/seat area either side which still sounds ideal in my mind.

[vlad01]

Yes that's them. I got them purely based on the ideal flow rate for the planned engine specs, well before I knew any of the stuff discussed in this thread with any sort of certainty.

The 63 lb deka have a 10-15 deg single cone, but I think my oem ones are even narrower than that when I actually measured out visually what 10 and 20 deg angles look like. I feel like the oem Holden ones are more like 5 deg from memory.


I think the original engine specs for what I want to do that ran the open wheeler Holden powered Reynard cars ran the Missubishi Magna green tops iirc, which was just a higher flowing version of what the EV1 style large body that the oem Holdens ran. I think the Magna ones were somewhere around that 30 -40 lb range, the Holden ran 19 lb, but exactly the same style Bosch injector. But as mentioned in this thread, they did the bare min in the tunes to run those engines, just turned up the idle to max, tuned VE, spark and AFR tables, the rest remained virtually stock.

[vlad01]

Found this handy info and video. So yeah sounds like I was on the right track for the most part, hitting the back of the valve seems to be the most important factor for at least port injection, so the spray angle is important. But things like sequential and EOI is another tool that gives you more flexibility with injectors, and of course the type of cam used as it is what ultimately sets the sensitivity of the engine to it's tuning.


https://www.efihardware.com/fuel-inject ... y-patterns

[delcowizzid]

Magna bluetops are 24lb they are the same as the stroker 215 v8 injectors .4 hole atomization disc single cone pattern

[buzzard]

Info may be correct, or my be correct for some engines. It may be possible to determine using CFD, my current knowledge does not extend that far. In my view these matters are best determined empirically.

Found this handy info and video. So yeah sounds like I was on the right track for the most part, hitting the back of the valve seems to be the most important factor for at least port injection, so the spray angle is important. But things like sequential and EOI is another tool that gives you more flexibility with injectors, and of course the type of cam used as it is what ultimately sets the sensitivity of the engine to it's tuning.


https://www.efihardware.com/fuel-inject ... y-patterns