[DeTomaso] An engine-bay shot from Japan

Kirby Schrader kirby.schrader at gmail.com
Tue May 11 23:18:19 EDT 2010


John,

The fuel, the cam overlap, the IR and the short stacks are all the reason.
Webers do it for the same reason.

I cracked up the other day reading about a guy that had a GT40 with Weber carbs and he complained that if he revved it and it backfired, it caught fire. However, he'd learned how do deal with it.... nail the throttle and suck it all into the engine! But I digress....

My point was just that you could throw a lot of fuel into the engine without have a duty cycle of 100%.
i.e., you can't deduce a 100% duty cycle just because you see fuel hanging in the air above the stacks.

Kirby

On 11 May 2010, at 10:09 PM, John Taphorn wrote:

> Uh oh - when the FI Meisters question my comments, I know to turn tail and run.
> 
> Yes, I propose that opinion because the engine is at wide open throttle and copious amounts of fuel appears to be exiting the runners.  That led me to hypothesize that the gaseous mass in reversion up the runner was picking up fuel being offered by the injector on a stroke other than the intake.  This led me to believe the duty cycle was longer than necessary and quite possibly 100%.
> 
> Although, when it comes to FI, I respectfully submit to you Obi Won.
> 
> JT
> 
> 
> ----- Original Message ----- From: "Kirby Schrader" <kirby.schrader at gmail.com>
> To: "John Taphorn" <jtaphorn at kingwoodcable.com>
> Cc: "DeTomaso Forum" <detomaso at realbig.com>
> Sent: Tuesday, May 11, 2010 9:59 PM
> Subject: Re: [DeTomaso] An engine-bay shot from Japan
> 
> 
> 
> OK, John... you gotta' splain that one to me...
> Why do you propose that because you see the reversion effect, the injectors are at 100%?
> 
> If, in fact, the injectors are at 100%, he's got a really poor design, in my opinion. The injectors would be too small.
> 
> Those are pretty short stacks... much like IDA's.... and that would explain the reversion at high rpm.
> 
> But, I could be wrong....
> 
> Kirby
> 
> 
> 
> 
> On 11 May 2010, at 8:56 PM, John Taphorn wrote:
> 
>> I am also surprised. I would guess that the EFI injectors are at 100% duty
>> cycle and raw fuel is being pushed out on the exhaust stroke due to overlap.
>> That is a terrific sounding engine
>> 
>> JT
>> ----- Original Message ----- From: "Dave Londry" <davel at emspace.com>
>> To: "DeTomaso Forum" <detomaso at realbig.com>
>> Sent: Tuesday, May 11, 2010 1:27 PM
>> Subject: [DeTomaso] An engine-bay shot from Japan
>> 
>> 
>>> http://youtube.com/watch?v=4eq5txuqRx4
>>> This is a road-shot of a 351C with an IR - EFI system.
>>> When the throttle plates are open you can see a lot of reverse-flow up
>>> the stacks.
>>> Surprised me - I thought that would only happen at lower revs.
>>> dave
>>> 
>>> -- 
>>> Dave Londry
>>> Embedded Spaces Inc. (ESI)
>>> davel at emspace.com
>>> 
>>> 604 589 9183 phone/fax
>>> 604 721 2278 cell
>>> Skype:embeddedspaces
>>> 
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