Thread: For Don Shilady

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I spent most of the afternoon studying this direct injection idea and talked with two engine builders. So far the best answer has already been studied as (click on)

What Ever Happened To Smokey's Hot-Vapor Engine? - Hot Rod Magazine

I learned that Brodix has an injection head for SBC that sprays fuel behind the intake valve but at ambient temperature so that is not supercritical injection. Overall the basic idea falls under Carnot's efficiency law for ANY heat engine:

Eff = ((T-hot) - (T-cold))/(T-hot)

Most normally aspirated gasoline engines run at about 25% efficiency because of the heat and fuel wasted in the exhaust. The old trick of putting a spark plug in the end of the exhaust pipe with a wire to the coil resulting in a long flame from the exhaust tells us that a great deal of fuel is not burned. The way the supercritical fuel injection as well as Yunick's "Hot Vapor" method work is by increasing the temperature of the input fuel mixture. So far I appreciate Jerry's suggestion to look for an LT1 from 1992-1997 as a better SBC 350 with emission controls but I found most of the Impalas of that time used 3.08 rear gears so that probably helped mpg more than the computer controlled injection??? Now I am going to study Yunick's tricks but he used a turbocharger as well as hot air and a very lean mixture. Overall it would seem that these methods border on burned valves and probably require forged pistons and even a diesel type heavier block to handle the higher compression ratio. Maybe I should try to find one of those old Buick diesel V8 engines for starters but were those blocks any sturdier to handle what was about 13:1 C.R.? Anyway I learned a lot today but other than mabe putting an aluminum carb spacer to heat the mixture a bit (without vapor lock in July?) I don't yet see any easy ways to improve my 17 mpg. Even so Yunick's Fiero project is very interesting. Are sodium-filled exhaust valves available for SBC?

Don Shillady
Retired Scientist/teen rodder

Don--------yes sodium filled ex valves are quite common---------


If you want to go more modern, look at the GM RO7 heads for nascar---------


And , I didn't mean to get the 92-97 for emissions so much as the computer and o2, and other sensors gave good control of the engine--


The impala engines were iron heads where as Camaro.f bird and vet were alum -------
you can use the latest ecm E38 which gives more control over about everything-----


My son Corey is doing dyno tuning dailey with the new Camaros, etc where they are making around 800 rwhp , idles around 800-850 and gets excellent mpg IF you keep you foot out of it-----


We have built dozens of the LT series engines over the last several years, but they are getting hard to get an adequate number of core blocks, but, there are wrecked complete cars that can be gotten reasonably for complete core package including wiring harness, fuel systems and engine driven accessories-----you can even do ride control with the right shocks from these vehicles------------

Thanks Jerry that is valuable information and I will look for a bargain on a rebuildable LT1 engine. Today I finally got my TPI-Tech speedometer unit set to read the total odometer as well as a calibrated mph and found my present setup is at only 997.3 miles so I plan to run this set up for a while. Does anyone have other less expensive suggestions to increase mpg? I found an economy site which suggested running tire pressure at 80% of the maximum and for me that is 28 psi on max 35 psi tires.

Best Wishes,
Don Shillady
Retired Scientist/teen rodder

Don,
Inquiring minds are wondering, if you're so focused on maximizing your gas mileage why did you even build a boxy, full fendered hot rod? It seems that you're so worried with your mileage that you're not able to simply enjoy the ride. Of course, perhaps your enjoyment is by making every outing a scientific experiment. If that's the case you should be having a ball!

Rodger, just for conversation I chose the '29 in honor of both my parents who graduated from high school (same class) in 1929 and in order to get financial support from my V.P. of Finance (wife) I had to promise to "make it look like a cute Model A". If I had my way I preferred a fenderless highboy with a deuce radiator shell. Without hard data I thought the 700R4 OD gear would allow me to get 20 mpg. I chose the 3.55 rear gear so that the product of the 700R4 low gear and the rear came out just a little lower than the 1947 Ford I had in high school with a 3.78 gear hoping the overdrive gear and the more powerful motor would get me to 20 mpg. As I recall the '47 got about 17 mpg most of the time so evidently the OD wasn't able to overcome the wind resistance of the frontal area of the '29 radiator and fenders and surely the fat-fendered '47 was a bit more streamlined. Of course, as you have guessed, I do try to find ways/excuses to drive the '29 just for the fun of driving it. The low gear acceleration is modest compared to cars with 4.11 gears but it is pretty peppy. I have a number of speed trap 35 mph zones nearby and there is a State Police barracks/office just around the corner so I have to take it easy. For reasons I do not quite understand the shift points of my 700R4 all seem to shift naturally in such a way that the engine varies only between 1900-2100 rpm all the way up to 65 mph. I could force the trans to stay in low or 2nd and see the revs go higher but the car is sufficiently light that at 55 mph I can accelerate to 65 mph almost instantly if passing is desired. Thus I am satisfied with the performance for my cruising but I am disappointed with the mpg. Two Dyno-Sims indicate the engine is only capable of about 300 HP at 4500 rpm but almost all of the time I am cruising at about 2050 rpm where the dyno curve is down around 125 HP. So yes, I am still in the stage of "fun-testing" my new toy and yes I am having fun!

Best Wishes,
Don Shillady
Retired Scientist/teen rodder

OK, so now your wife is satisfied that she got the "cute Model A", and I expect that after all of these years she probably rolls her eyes and/or shakes her head whenever you start talking about "...a scientific experiment", am I right? So just like Vic Edelbrock used to do, drop the fenders and set them aside, ready to go back on at the right time (which may never come....), lose the tall windshield for something sporty like a DuVall, and when she asks just say that you're ",...continuing to gather data on the effects of weight and wind resistance relative to mileage and efficiency in a modern hot rod." If she asks, "Just how long will this experiment last?", you can use the "Darlin' you know that science cannot be rushed.", and start planning for the next round of modifications.....

19-2100 might be your torque converter------------

Jerry that is an interesting observation. As far as I know the torque convertor stall is 1600 rpm. While I was looking up LT1 and related Camaros from '92-'97 I noticed that the auto transmission cars had 3.23 or 2.73 rear ratios with four speed trans and 3.42 with the six speed trans. While those Z28 cars got 22-24 mpg on the road none of them had a rear ratio as low as my 3.55 Maverick rear. It is possibly ironic that I changed what was a 2.7 Maverick rear to 3.55! I am a victum of my own frozen memories of only Ford ratios of 4.11, 3.78 and 3.54 which were available for the old banjo rear ends, although I think there were some 3.2?? ratio rears used by lakes streamliners. I thought I was being conservative keeping the ratio near the old Ford high ratio of 3.54. Jerry's comment suggests consideration of my torque converter stall speed and a new "experiment" of watching the Tach with acceleration in low or second gear and potentially some more experimental "fun" but at this point I think it is a blessing to keep the rpm low for good mpg as long as the 700R4 is not slipping. As far as I know the stall speed of my converter is 1600 rpm. So I will try to accelerate with the trans restricted to low gear and again restricted to second gear after the first shift.
For Rodger, my wife is not eager to ride in the car anyway but does seem to like the look of it. It is not easy to remove the fenders because I have the Bebops all-in-one fenders attached to the floor panel. At this point I now understand that my 3.55 rear is a bit low for good economy so another "scientific experiment" leading to more "fun" is to run some mpg tests using 87 octane instead of the 89 I have been using and if 87 is OK then maybe I can achieve some economy financially with lower cost fuel. I have run the car on 50-50 87-89 without any pinging but the C. R. is about 9:1 so that leads to another "fun experiment". By the way Rodger, what mpg do you get with that 347 Ford?

Don Shillady
Retired Scientist/teen rodder

Don,
A couple of comments. First, that's too bad about the fenders being integrated with the floor, but I was not really serious about changing your body configuration back & forth. It is what it is, right? Second, you want to be cautious about dropping your rear gear ratio too much unless you know the characteristics of your specific engine's torque curve. If you drop it down too the point where you're backed down on your curve too far you're going to actually lose efficiency - have to give it more fuel to maintain speed as opposed to cruising easy. And before you go there, saying "..my engine is essentially a _____ (fill in the blank), so my torque curve is ______ (fill in the blank)" is NOT going to cut it. Each engine combo is different, and a small change in the cam timing can have big impacts on your torque. Third, you know that you can find your stall speed by dropping into gear, locking the brakes and depressing the accelerator, right? It'll go up to stall speed and stop increasing rpm at your true stall speed. Just remember to let off the gas before you get off the brake, or you'll learn how well it'll launch!!

Originally Posted by Don Shillady

By the way Roger, what mpg do you get with that 347 Ford?
Don Shillady
Retired Scientist/teen rodder

My mpg is all over the map, probably depending on how much I play more than anything else. On the way to Des Moines we made an un-planned stop after only 75 miles of highway cruising between 75 and 80mph, everyone topped off and I got 21mpg, much to my surprise, but the next time we stopped it was down to 16. Short trips into town and back, with a couple of attitude adjustment cruises of fifty to sixty miles thrown in I'll get 12 to 13 mpg over a tank full, and I'm running 10.3CR so it's 91 octane for me, ethanol free whenever I can. I don't really sweat the mileage, but consider it more an input into my fuel map tuning than anything else. I'd really like to get my air/fuel ratio indicator mounted in the dash, hardwired into the ECU with the wide band O2 input, but haven't gone there yet.

One of the things you might consider is running a vacuum gauge where you can watch it while you cruise. If your carb is tuned right, the vacuum reading will tell you more about efficiency than about anything else. Have you pulled a plug or two after one of your "economy runs" to see how your mixture looks by electrode color?

If you get really serious about using peak torque to dial in your ideal cruise RPM, run the car on a chassis dyno and use your peak torque RPM to select a gear ratio!

Thought I had a dyno printout, but they must be on the laptop.....

Well thanks to Rodger and Dave I got to do a little "fun experiment" again today. I live on a black top two lane branch of what was once Route "1" back in the early 1800 era. Now it is just a backwoods branch parallel to U.S. Route 1 but a nice test run for about a 1.5 mile stretch. Holding my 700R4 in second gear (Lokar second) and putting the pedal to the fiberglass the shift point from low to second occurs at about 3100 rpm. Holding the trans in just low gear allowed the engine to go easily to about 3700 rpm so the shift point is somewhere around 3000 rpm. More gentle acceleration showed a shift point from low to second around 2500 rpm. Thus OD kick in holds the rpm down around 2000 rpm in "normal" driving. I recall reading about the OD 4th gear automatic down shift having a lower limit of about 1900 rpm and I have the automatic electronic shifter so I guess the pressure shifts are set just above where the minimum kick-in for the OD occurs. As long as the OD doesm't slip I think it is good that I can cruise at only 2000 rpm for economy and engine life. I only see the tach go over 2100 rpm while cruising at 55-60 mph but I can get it to go up if I punch the throttle but then it settles down once the speed stabilizes. I guess this has something to do with the torque convertor but I see the same thing on both my 1998 Sunfire and my 2008 Impala and they both have 4-speed auto trans with similar gear ratios.

Don Shillady
Retired Scientist/teen rodder

I'm not up on the 700R4, but every automatic I've ever had holds in to very near red line if the pedal is at WOT. If it were mine and shifting out of low to second at 3100rpm I'd be searching for the reason why....
Also, I thought your question was related to the stall speed of your converter. In your driveway drop it into gear, hold your brake very firm and put your accelerator to the floor. The engine will go up to a specific rpm and "stall" there. Let off of the accelerator, and now you know your converter stall speed.

Rodger, although I have received a LOT of useful information on this Forum it is a weakness that we have to resort to descriptions instead of hands-on experience. I will try the stall experiment first chance I get but I am content that my 700R4 behaves almost exactly the way my 1998 Sunfire 4-speed and my 2008 Impala 4-speed behave. On the low gear only test I backed off in low gear at 3700 rpm because the test road is short and I was approaching a curve. Depending on how hard I press the pedal, the low to second shift may be at 2000 rpm, 2500 rpm or 3100 rpn where again I backed off on the 3100 rpm shift because I ran out of room before an impending curve. Ironically just around the bend there was a county patrol car so I slowed down just in time! I don't really understand the torque multiplication of the torque converter but it seems to work in the same way on all three of my GM driveline cars.

Don Shillady
Retired Scientist/teen rodder

Originally Posted by Don Shillady

On the low gear only test I backed off in low gear at 3700 rpm because the test road is short and I was approaching a curve. Depending on how hard I press the pedal, the low to second shift may be at 2000 rpm, 2500 rpm or 3100 rpn where again I backed off on the 3100 rpm shift because I ran out of room before an impending curve.

That's just how it's supposed to work. The torque converter is nothing but a fluid coupled pump, varying the amount of pressure into the transmission, with pressure switches, check valves, etc, etc in the tranny using that pressure to control gear selection. You're converting the torque of the engine to pump pressure in a smooth coupling that allows slip. Google "how does a torque converter work" and you can find a myriad of explanations.

Did you give the trooper a little wave as you met him?

Don post a picture of the linkage set up on your carb to trans----------