m42racer

LOL,
Swing on in Mr M42 Spacer.......
When you do get beyond 500 bhp you will become more focused and the little raindrops will make more sense..

Please explain your reasoning.

A.Wayne

Sure after you explain your disposition with those responses...

951and944S

Bump if for nothing but the comedic value.....

A.Wayne, you gonna be at Sebring this weekend....?

T

333pg333

Be sure to take your Mace if you're catching up with Mr Wayne. He comes out swinging sometimes. lol

m42racer

A Wayne.

I am interested in your theory here. Please explain. No hidden agenda here, just really interested in hearing your reasoning.

Duke

I don't understand what the fuzz is about?
The available timeframe for an injector to inject goes down as rpm rises since each engine revolution goes faster and faster. It doesn't get more logical than that.

Or are you 2 just picking fights...

m42racer

Duke,

I agree with you. No fight here. I just do not understand his point about the Injector needing to be larger for higher RPM. Maybe I can learn something I do not already know. We all may.

The Injection is per revolution of 2 revolutions. This time goes down with speed as you state. The volume of fuel injected is based upon the volume of air ingested, and this goes down per stroke as the time the valve is open is less. The overall volume may be higher for both as the number of strokes increases, but per stroke the volume gets smaller, does it not? The injector size is based upon fuel required per stroke? Injectors are sized upon their ability to flow at measured pressure rates at 100% DC.

I am interested in haering his take? No fight, no agenda. Please inform us of your reasonings to say why the injectors need to be bigger based upon your initial statement. Maybe I have the wrong understanding of how these things are configured.

A.Wayne

Duke Thanks,
Your explanation was perfect in very simple terms , I never attack anyone , I just respond to those that do.....in the end my point is there is no fast and hard rule as there are many factors in sizing the injectors. Anyone working around this stuff can give you a ballpark figure as to what to use , every setup is different as to boost pressure ( power ) rpm( time) and target AFR ( headroom) , my suggestion go 30% -40% bigger than you think you need.

A.Wayne

LOL,
No mate , I bring beer for drinkers , Laughter for jokers , cars for drivers and gloves for boxers , you know kind of fit in to my surroundings ...........

333pg333

Well so long as it's some of the very good Micro Brewery beers that you guys have as opposed to the rather ordinary commercial beers in the US. Big difference!

However isn't there a possible issue of cylinder wash with overly large injs? I mean why wouldn't we all have huge injs if that solves any possible issues without side effects?

eniac

Idealy you want injectors that will run about 80% duty cycle. This will allow for some room in either direction since and as it has been stated....none of this can be calculated exactly. Too large of injectors will cause way too low of a duty cycle on idle, along with a decreased response since they cannot accurately flow that little of fuel.

Duke

First, glad we're all getting along

As long as the A/F's are fine it's ok. Modern EFI-systems can handle injector times down to 0.XX ms.

I ran 95 lbs with batch on my DTA system.
When it's time for E85 I'm going with 1600cc's

A.Wayne

LOL, Duke
yep 95's are good on a DTA , connect them direct for good idle control , you will have to go seq on the 1600 for street use or FP control below 100 KPA .... I would prefer twin injection , worth about 25-35 bhp over straight 1600 ,use 2 sets of 95 lbs ...If running seq anything above 70 % duty cycle is not considered seq operation...

m42racer

So your statement about the Injectors having to be bigger at 9000RPM for 500Hp than at 6000RPM for the same power is not what you mean?? I don't get it. Did I read something wrong or have you changed your view??
I have never heard of this before. Could you explain this in more detail so I can understand what you mean. I really would like to know as I feel I may be lacking so important information about Injector sizing.

Thanks in advance.

m42racer

Are you saying that with the shorter injection time availbelat teh higher speeds, a bigger Injector will inject more fuel at the same pressure and opening time by virtue of a bigger pintle?

But does not the air vol go down as well? Most maps I have ever seen have smaller injector times at the higher engine speeds than at the lower speeds as the number of injections increases. The biggest BSFC is always at peak torque is it not? Is this not the reason why the A/F always goes the leanest at peak torque and is adjusted typically to run a more acceptable AF number, and the BSFC number is always higher there?

I am realy interested in your take on this.