Sandy Brown/ Colin Satchell Throttle Bodies

[Sandy 191]

I use the most recent injector designs available and it's not really an issue of the injectors, but the ECUs ability to control them and the length of the injecting cycle. As I said before; i'm quite frequently told that bigger single injectors are just as good, but when I find that well chosen twin injectors map and work better, what can I say? I'm not peddling anything, just voicing what I've collated from my engine building, inlet design and mapping experience.

 

When I say staged, I mean running on the first set, then switching to both together; stepped running on inners, then switching to outers only.

 

Power level is irrelevant, I've seen the same benefits from my small TU engines to big BMWs.

[sideways danny 0]

I can see the benefit of stand-off in very high revving applications (talking 10k+) running very high compression, where the fuel is atomised earlier to create a refrigerant effect on the intake air, but i dont see that this is where it's being suggested that it's used. Lack of injector control? Quite simply, buy a better ECU

[sideways danny 0]

imo if you run of 80% duty your an idiot....think about it an injector is a coil, coils generate heat. the longer you leave to coil on for the more heat it generates.

density and temperature are inversely proportional therefore by heating fuel you are discharging a 'less dense squirt' into the intake gas stream.

this is one of the many reasons that all injector manufactures advise that injectors should not be run at 80%+ duty

how long do you dwell at full throttle at 8k rpm? I would say for the few seconds you will be at a single load site it is quite safe to go to 90% on the rarely visited sites. Injectors will simply just not overheat in that time frame, they're being cooled by a constant flow of liquid through them also. I can honestly say in 10 years of working with modified cars, I've never seen an injector fail from being run at excess duty cycle, and having discussed it with a number of high profile mappers, they havn't either.

 

you can trigger accel enrich on a programmable ecu by moving the throttle quickly, thus incurring an enrichment and increasing injector duty above what it was running at. i think thats the point some one was trying to make.

true, but not relevent. As i said, it wont be functioning anywhere you'd need to be concerned by duty cycle limits.

 

 

Better injectors are cheaper and simpler to install than an extra 4, just thinking about the custom fabrication you'd need. I'd rather shell out £250 and just fit them personally.

[welshpug 1,661]

in the engines Sandy builds, they see 8k rpm VERY regularly

[petert 588]

Maximum injection time occurs at the torque peak (not max. hp), where you do spend most of your time.

[wracing 19]

the reason i quote a power figure was simply to say your prob not going to be running the equipment that works well and cost effectively with staged injection under that power figure.

 

off topic sandy are you the man to speak to about suspension geometry?

 

i forgot danny high profile mappers know better than the manufactures and designers of these injectors. as DrS said its about removing/improving on every inefficiency thus if your heating the incoming fuel, its not good!!

 

with the hi resolution code available from ecu manufactures i still think that for high impedance injectors the injector is the bottleneck in good and stable fuel control at the injectors low delivery points.

but on the other hand low impedance (peak and hold) its the driver circuity, few ecus provide low impedance support even though this type of injector has a faster opening time.

 

james

[DrSarty 90 1 Cars]

off topic sandy are you the man to speak to about suspension geometry?

 

Sandy would direct you to Colin Satchell (Eeyore) as they work together and Colin's the fabrication and geometry man. They work as a team and share knowledge to reach a 'unified purpose', i.e. sh1t hot cars.

 

This is a very interesting topic, and I see amazing things from James in years to come. Wracing> You certainly have the technical knowledge and theory, and I think it would be amazing to see someone like you work with someone like Sandy to get 'hands dirty' and test out how far theory can be pushed.

 

Excellent stuff IMO.

 

EDIT: James> I've just noticed your location. Do you ever go over to Emerald and spend anytime with Dave? Might have an interesting outcome.

Edited June 28, 2009 by DrSarty

[sideways danny 0]

i forgot danny high profile mappers know better than the manufactures and designers of these injectors. as DrS said its about removing/improving on every inefficiency thus if your heating the incoming fuel, its not good!!

 

wow. That wasn't taken out of context at all, was it. I can see where this discussion is going, sadly, so i'll leave it there

[DrSarty 90 1 Cars]

I can see where this discussion is going

 

Enlighten us please. I'm sure there's no plan; it's an open discussion. I'm keen to learn and you're contributing, so why dash off?

[Sandy 191]

I don't really see what anyone's trying to achieve here other than to pointlessly discredit my reasoning for using twin injectors? As for using a "better ECU" or buying brand new high quality injectors, you're casually adding far more than £250 to the cost of the set up and if near perfect fuelling from cold start, through all driving conditions to peak rpm WOT, can be achieved for the extra £150 or so it really costs us to run 8 injectors, can you not see why I like to do it?

Edited June 28, 2009 by Sandy