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LZ23 Big Bore MPG's


MicroMachinery

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Hey guys, just wondering what kinda MPG's you're getting out of your LZ engines. Mine are low. Like, f*cking low! Getting between 10-14mpg, depending on how I drive, and that's not with low gears, either; 3.9's. Not sure if my Dual Hitachis are just tuned like shit, or if this is what's to be expected. Thanks!

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Hey guys, just wondering what kinda MPG's you're getting out of your LZ engines. Mine are low. Like, f*cking low! Getting between 10-14mpg, depending on how I drive, and that's not with low gears, either; 3.9's. Not sure if my Dual Hitachis are just tuned like shit, or if this is what's to be expected. Thanks!

Dual Hitachis, what type?

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uberkevin said around 15 with his. He had the SUs EagleAdam had before he went KA-DE. Adam said bigger jets, fuel dumpers really. 

 

 

The one I had was about 18-22 depending on driving habits. 40mm Roadster SU's. 

Not super positive mine was the big bore or the Rebello copy LZ22. I've heard many different things about that motor.

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I have got as good as 23mpg going fairly fast with the LZ23 in my work truck, it was empty and not pulling my trailer, would have been more except I was going 90+ a couple times, I was breaking in the engine at the time, going fast and then letting off a lot.

I have 38mm SUs on mine, they are plenty of carb for me, the thing will go way faster than I want to go, I have 437 gears in the rear, and I was going past 5000rpms a few times, and that was in 5th gear, I broke the speedo needle off on one of those high RPM events that trip.

I must have done the correct things, because it doesn't use much oil at all, and i am hard on that truck, I haul heavy loads all the time.

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That gives me hope. I figured that since the 46mm carbs were used on the L24, that they would be appropriate for an LZ23. Perhaps I assumed wrong. The 38mm's felt to me like they didn't have much top end, and ran out of breath much earlier than the 46's. I guess there's always a compromise.

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10-14 is just wrong. You should get better than a Z24 in a truck. In a light car probably in the 20s on a trip. Hell my last Canby trip I got 34 MP(Imperial gallon) that would be over 28 US gallon highest and about 23 US gallon worst. 25 MPG on average... now this was on a trip.  I'll say 20 ish all round mix. So how would a 15% larger displacement engine use up to twice as much gas?

 

46mm carbs are still too big?

Jets wrong size?

What color are the plugs?

Short trip to work and back home?

Chokes stuck on

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I get 16 in my Weber 32/36 Z24 powered 720. That's a 4x4 with a three inch lift rolling 31x10.5s. There has got to be some more mpgs you can pick up. If it's that terrible, I'm much less interested in building one...

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You guys are way off on your jets, i would say mine is just slightly worse than stock.. I get about 400-500kms out of a tank so abot 10 liters per 100 k or so. Im jetted for best power all the time basically, 12.5-13 afrs. Thats about 23mpg.. Which sounds about right to me.

I could probibly get it to sip even less gas but its really happy with these jets, you can tell the difference if you go up or down a size.

 

I have weber 45's with 40 mil throats and full race cam (300 duration) and high compression. Big bore 2.3

 

Buy a wideband and a needle/jet kit and reap the rewards. :)

 

Also theres unknowns to me with the su's, like trying different dashpot oils, springs etc.

I know on slide bike carbs float height and needle/seat adjustments can do crazy things, and that probibly applys to the su's too

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You guys are way off on your jets, i would say mine is just slightly worse than stock.. I get about 400-500kms out of a tank so abot 10 liters per 100 k or so. Im jetted for best power all the time basically, 12.5-13 afrs. Thats about 23mpg.. Which sounds about right to me.

I could probibly get it to sip even less gas but its really happy with these jets, you can tell the difference if you go up or down a size.

 

I have weber 45's with 40 mil throats and full race cam (300 duration) and high compression. Big bore 2.3

 

Buy a wideband and a needle/jet kit and reap the rewards. :)

 

Also theres unknowns to me with the su's, like trying different dashpot oils, springs etc.

I know on slide bike carbs float height and needle/seat adjustments can do crazy things, and that probibly applys to the su's too

 

At 10-14, I almost say it's worth throwing my Mikuni's on just for a laugh. There's no way on God's green hell that they could do worse than that and still run.

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If your getting 10mpg with webers you must have fuel pouring out your exhaust, or you drive wfo in first with the brakes on.

 

Also im running avgas which likes to be jetted a little fatter than pump gas.

 

No reason you cant be around 25mpg with twin 44's, 45's or those z car su's.. Im pretty sure 240z's with su's dont get 10mpg.

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