do we really need 2xxwhp every single day on our daily drivers? i mean sure, we build our engines for max whp, have a couple legal races, and then go home. now what? what if with a flick of a switch, we go from max whp, to max mpg.


has anybody tried this before? im talking about tuning our 2xxwhp k/b/h/d series for lean, mean, tree hugging machines.

what is the "leanest" an engine can go without blowing up, with proper tuning of course, to achieve max mpg possible? im talking about cruising afrs.

 

its called partial throttle tuning. i believe. try searching that and you will probly get the answer you are looking for.

 

doesnt answer my question about running super duper lean...

 

Most tune for 14.5 to 15.1 for partial throttle.

I get 30 to 32 mpg with a B18C and J1 transmission.

 

how high afrs can a 11:1 motor go without detonation on partial throttle???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RNbuilt &raquo;</TD></TR><TR><TD CLASS="quote">how high afrs can a 11:1 motor go without detonation on partial throttle???</TD></TR></TABLE>

Depends on the camshaft. Your best bet is to find a load control dyno.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RNbuilt &raquo;</TD></TR><TR><TD CLASS="quote">do we really need 2xxwhp every single day on our daily drivers? i mean sure, we build our engines for max whp, have a couple legal races, and then go home. now what? what if with a flick of a switch, we go from max whp, to max mpg.


has anybody tried this before? im talking about tuning our 2xxwhp k/b/h/d series for lean, mean, tree hugging machines.

what is the "leanest" an engine can go without blowing up, with proper tuning of course, to achieve max mpg possible? im talking about cruising afrs.</TD></TR></TABLE>

You can go pretty lean at low loads without misfire, actually.

I ran my personal car at 16.5-16.8:1 in the cruising range for a while. It required a decent amount of timing to smooth things over.

You DO NOT want to go lean at high load situations.

The simplest answer to your question is this:

If you want good gas mileage, you don't need two maps. You just need a very fuel efficient lean cruising portion of the map. Your high load/WOT columns should never be compromised for the sake of economy, as there is no reason to.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mar778c &raquo;</TD></TR><TR><TD CLASS="quote">

Depends on the camshaft. Your best bet is to find a load control dyno.</TD></TR></TABLE>

I have NO clue who would have one of those...

- Derek

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RNbuilt &raquo;</TD></TR><TR><TD CLASS="quote">doesnt answer my question about running super duper lean...</TD></TR></TABLE>

Oh, super duper lean --- thats a new realm your diving into

Youd be better off targeting 14-15 at cruise and grabbing a long 5th gear for your trans

Lower revs = lower fuel demand = better mpg

A properly tuned NA car isnt gonna find 5-10mpg out of nowhere -- your best bet is to lower your revs....unless your at 11-12 at cruise on a mickey mouse tune --- then you may just find a few mpg

Dynapack FTW

 

You wouldn't happen to have a load control dyno?

 

Buy a good quality vacume guage.

 

Lower RPM doesn't automatically mean better economy.

RNbuilt, are you shooting for a 220whp stock block/head C5 still or are you going for D15Z1 economy?

 

Anyone got the link to the crx getting like 56+ MPG and still putting out decent HP? I can't remember who it was.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">Lower RPM doesn't automatically mean better economy.</TD></TR></TABLE>Exactly.
The main reason a longer 5th would increase mileage is because of the higher load it would place on the motor(other variables remaining the same), not the lower revs.

Also, just going ever leaner wouldn't automatically increase fuel economy either. You need to tune for best bsfc at cruising rpm and load, which is usually between 15.5-16.5 a/f.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RNbuilt &raquo;</TD></TR><TR><TD CLASS="quote">doesnt answer my question about running super duper lean...</TD></TR></TABLE>I couldn't get the lighting right, but it's legible.
As you can see, if you keep going leaner, it doesn't mean you'll keep using less fuel. At some point, bsfc will start to rise again. It also increases with decreasing load, as well as the a/f ratio at which you'll see best bsfc.

http://www.screenshots.cc/images/749_100_3223.jpg

 

How does increasing engine-load increase fuel econ? (just drive up-hill on flat tires, if so.)

It seems that you'd want to reduce the load on the drivetrain as much as possible to lower bsfc; better aero to lower wind-drag, lower weight for easier acceleration, lower rpm to reduce drivetrain friction. The more cycles the engine has to turn to maintain a certain speed/ power output, the greater its losses in heat/friction and pumping.

 

Less theory and more applied knowledge please.

A lean mixture coupled with part throttle (where we want MPG) translates into a a/f lower charge density (air and fuel molecules are not as close to each other) likes a more timing than WOT. So just creep on timing till you find optimal MGP without melting the motor.

Also if you want to run higher than 14.7 a/f you'll need to run open loop because closed loop with a narrow band hunts for 14.7.

Common sense fo da win!!! Sorry you can't get this info at TeamIntegra.net. Best place to find where da best price on OE floor mats for da win!!!!

 

Applied knowledge...

My mileage went up after replacing my .702 5th with a 1.000.

 

applied knowledge

i get 42mpg at 70mph/2800rpm at 16.2:1 AFR

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">applied knowledge

i get 42mpg at 70mph/2800rpm at 16.2:1 AFR</TD></TR></TABLE> Is that your highest vacume number?

 

You can also widen da lobe centers a lil to keep a lil more heat in da motor.

Cam knowledge fo da win!!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Master of the Universe &raquo;</TD></TR><TR><TD CLASS="quote">You can also widen da lobe centers a lil to keep a lil more heat in da motor.

Cam knowledge fo da win!!!

</TD></TR></TABLE>

Can I do this with a dremel?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slofu &raquo;</TD></TR><TR><TD CLASS="quote">How does increasing engine-load increase fuel econ? (just drive up-hill on flat tires, if so.)

It seems that you'd want to reduce the load on the drivetrain as much as possible to lower bsfc; better aero to lower wind-drag, lower weight for easier acceleration, lower rpm to reduce drivetrain friction. The more cycles the engine has to turn to maintain a certain speed/ power output, the greater its losses in heat/friction and pumping.</TD></TR></TABLE>Do you know what variables are? It doesn't seem as if you do.
Decreasing torque multiplication will not increase the horsepower requirement for a specific vehicle to maintain a specific speed. Increasing wind resistance, rolling resistance, etcetera, will. Which is why I said other variables remaining the same.
Decreasing torque multiplication by using a higher gear and/or using an engine of smaller displacement(other variables remaining the same, including weight) won't change the horsepower requirement, but both will increase the load on the engine...

 

oil drainback tubes, lots of crankcase ventilation, gasports, low tension rings, extra oil return holes around the oil ring shelf, loose bores, a high temp thermostat and a wrapped up exhaust would all help.

in my opinion, you want to be standing deeper in the throttle at cruise so that the throttle blade is wider open and the engine isnt sucking high vaccuum against a tiny opening. to avoid detonation with a lean running engine, id go with a lowish rod to stroke ratio so the piston pulls away quickly from TDC. having a long stroke helps turn the same cylinder pressure into greater torque at the crank.. and the increased torque allows you to stay lower in the rpm range.. where frictional power robber is much less than upper rpms.

keeping the engine hot reduces the heat transfer from your chamber into the water jacket, and wrapping the exhaust will do the same. the hotter exhaust gas temps will have a little better exhaust scavenging effect.. and an advanced intake cam (valve that closes shortly after TDC) will trap higher cylinder pressure at low RPM than a retarded intake cam.

i had an otherwise stock d16a6 with PM3 flat pistons that were in an .008" piston to wall clearance bore with new rings and a rough hone/hard breakin. the pistons stuck out of the bore and actually hit the head at max revs, but it had 240psi cranking compression, under 5% leakdown and never smoked or burned oil.. just clacked like a typewriter. compression was around 10:1 but the piston was flat as a board and i ported the head. it could run 18:1 air fuel ratio, tip-in wide open from 2,000 rpms in 5th gear and never ever knocked. got 41mpg in a sedan and went great. i think i used a 4 speed STD tranny that i added a 5th gear and forks to from an HF.. hard to remember but it was a long, long tranny and the motor pulled it great.

motor just sold to some kids from HT a few months ago in my buddies hatch actually.

 

i think i would try a large-ish throttle body on a small-ish plenum and runner intake setup.. and then fine tune by trying various intake tubes. ive had really good luck with small diameter (like 2") yet very long intake tubes that had an almost football shaped, stubby, abrupt expansion chamber right on the throttle body. the long/thin intake would enhance the bottom end feel but choke up the top. when i started adding expansion chambers and playing with intake cam timing, id find that the bottom remained and the top woke up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">applied knowledge

i get 42mpg at 70mph/2800rpm at 16.2:1 AFR</TD></TR></TABLE>

Are you using a F22 5th now?