Great 2 part interview with Tony Rudd

[LGAFF]

Reading a 2 part interview with Tony Rudd on the LT-5 development.....a few quick notes....

-The dual injector system was to ensure that the car could idle at 500 rpm to meet CAFE requirements....as was the center throttle body. He refers to the primary as the"swirl port" and the 2ndry as the velocity port...he said the primary had more bend to create swirl...interesting

-Lotus actually mocked up one of their 4V V8s with the LT-5 fueling system to test it and prepare for the LT-5 build....Rudd called it a piece of history they preserved it at Hethel

-Lots of discussing on the oiling system...namely that the engine oil shooting out the top only happened on deceleration...once air speed would slow the oil would drop out of the air into a liquid.....Lotus traditionally used the entire V of the engine to build a giant box to handle the issue, but with the AC/ALT/Starter in the V did not make that possible....

Need to find more on Tony, he seemed to be up to date on both the politics of the build as well as the technical.....

[LGAFF]

Wow his book runs from $100-180

http://i134.photobucket.com/albums/q115/lgaff/KGrHqQOKjoE5bbzvwprBOchdiHptQ60_12.jpg

[LGAFF]

After reading Tony Rudds interview, this engine is without a doubt the first true LT-5, Lotus mocked up the 2ndry throttles and fuel injectors on the 4 ltr 909 to test the layout for emissions with parts from Rochester

http://i134.photobucket.com/albums/q115/lgaff/LV8indaSM.jpg

[carter200]

If only our engines had cam covers like those..........

[Hib Halverson]

Any interview with Tony Rudd had to have been interesting, but dual injectors was not a Lotus idea.

Mike Dupree, a brilliant development engineer at GM who worked with engine controls, came up with the idea. Early in the LT5 program, GM and Lotus found that existing electronic fuel injectors of the mid/late-80s, lacked the bandwidth to be able to deliver the fuel flow for a 400 hp engine at wide open throttle as well as the very low fuel flow typical of part throttle operation with maximum fuel economy and minimal exhaust emissions. Dupree's idea was elegant in its simplicity. Two injectors per cylinder meant each injector only had to deliver half the fuel flow each cylinder required at WOT and, thus, could be effectively controlled in the LT5 application.

I'd have to do some more research but I'm pretty sure the 4-liter proof-of-concept engine predates the dual injector idea.

[Paul Workman]

Any interview with Tony Rudd had to have been interesting, but dual injectors was not a Lotus idea.

Mike Dupree, a brilliant development engineer at GM who worked with engine controls, came up with the idea. Early in the LT5 program, GM and Lotus found that existing electronic fuel injectors of the mid/late-80s, lacked the bandwidth to be able to deliver the fuel flow for a 400 hp engine at wide open throttle as well as the very low fuel flow typical of part throttle operation with maximum fuel economy and minimal exhaust emissions. Dupree's idea was elegant in its simplicity. Two injectors per cylinder meant each injector only had to deliver half the fuel flow each cylinder required at WOT and, thus, could be effectively controlled in the LT5 application.

I'd have to do some more research but I'm pretty sure the 4-liter proof-of-concept engine predates the dual injector idea.

Thanks for that Hib. I wonder why they didn't go to a variable fuel pressure approach to the low speed, big volume injector issue? Maybe they did on the next gen of the LT5, as it had only one injector.

P.

[XfireZ51]

Thanks for that Hib. I wonder why they didn't go to a variable fuel pressure approach to the low speed, big volume injector issue? Maybe they did on the next gen of the LT5, as it had only one injector.

P.

I believe electronically controlled variable fuel pressure is what they use for the LS-9. When I built my Xfire, I had to use 80psi BB TBI injectors @ 20psi to supply fuel for WOT. BUT at 20psi fuel pressure, the pulse width couldn't get short enough for proper idle. I used Aeromotive 13301 VAFPR for this purpose.
However, the Engine Control Management must accommodate the use of a
varying Base Pulse Constant in the calibration. Worked great. Motor idled great
and yet would be at about a 75%-80% Injector Duty Cycle at WOT for a 12.8 AFR. And this using modified TBI truck ECM code from a 7747 ECM. That same ECM can now be upgraded to handle MPFI, NOS, and forced induction.
BRILLIANT! I keep begging them to do LT-5 code ;)

[LGAFF]

Hib not saying it was a Lotus idea just that they built one to get ahead of the curve....look at the TB on the engine above....looks very familiar...also note the 909 did not use a plenum style intake as above...

Any interview with Tony Rudd had to have been interesting, but dual injectors was not a Lotus idea.

Mike Dupree, a brilliant development engineer at GM who worked with engine controls, came up with the idea. Early in the LT5 program, GM and Lotus found that existing electronic fuel injectors of the mid/late-80s, lacked the bandwidth to be able to deliver the fuel flow for a 400 hp engine at wide open throttle as well as the very low fuel flow typical of part throttle operation with maximum fuel economy and minimal exhaust emissions. Dupree's idea was elegant in its simplicity. Two injectors per cylinder meant each injector only had to deliver half the fuel flow each cylinder required at WOT and, thus, could be effectively controlled in the LT5 application.

I'd have to do some more research but I'm pretty sure the 4-liter proof-of-concept engine predates the dual injector idea.

[Kb7tif]

Good Stuff!

[LGAFF]

If I get my scanner working will post some of these....

[LGAFF]

"To our delight, we ran the first engine May(1985) and it worked. We had been running in parallel: we had shipped one of our 4 liter engines to Detroit, and we mocked up the induction system we'd plannned to use, which saw the two inlet ports and one inlet port is throttle. The whole induct system is mocked up on one of our V8s. We can show you the engine-we've preserved it. We think it's a piece of history.

And that was when we coined the phrase that it's got 11 throttle butterflies and 16 injector nozzles. That was the week we had to go down to talk to AC Rochester about the link for the injector nozzle."

Tony Rudd

[Hib Halverson]

Thanks for that Hib. I wonder why they didn't go to a variable fuel pressure approach to the low speed, big volume injector issue? Maybe they did on the next gen of the LT5, as it had only one injector.

P.

I can't remember what they were going to do on the still-born 96 engine with VVT. I'm embarassed that I can remember as I've talked to Graham several times about it over the years, but by 1992, when they were developing the 475-hp engine, it's possible there was an injector out there which both flowed enough and could be controlled at small pulse-widths.

As for the LS9 in the 3G ZR-1, yes, it does have variable fuel pressure levels....three of the, in fact. A fuel system control module changes pressure to fit fuel flow demands.

As to why that couldn't have been done 25 years ago? Uh well...the technology didn't exist. Even if there had been an AFPR which could be changed rapidly enough, the control system would have been an even bigger challenge.