Turbo YZ

It would have to be a system that's easy to tune, doesn't take up any more space, doesn't draw much electricity and the cost would be another factor?

Rail pressure has to be higher than with a carb, so the pump would draw more current. The EFI might pull two amps at full tilt, maybe three if a coils is getting driven, too. Ease of tuning is subjective. The learning curve can be steep, but like anything, you know what to do once you learn how to do it. :thumbsup: MicroSquirt and Ecotrons are two options that run around $500. The Ecotrons is new and not widely used or known yet, but it is a complete system aimed specifically at one- and two-cylinder powersports engines. I'm not sure if the TB and ECU are available separately.

I'm not saying you should jump ship to EFI, especially if your carb setup is getting the job done. It just sprang to mind when you mentioned needing to pull timing under boost and it does offer a lot of other advantages. You could even use separate selectable fuel and spark tables for different fuels like gasoline/E85. Datalogging alone is a huge benefit IMO.

The electrical system on YZ450's is a huge handicap when considering EFI. To upgrade a Gen2 engine to WR stuff, you need a crank to begin with, and it ends up being about $1000. Gen1's require crankcases. None of the Gen3 OEM EFI stuff will fit, and there are no reliable aftermarket YZ450 stators that I know of.

Electrosport is supposed to be coming out with a new stator soon. All I need is to maintain my battery a little. Its lasting just over a tank of fuel right now.

My clutch finally started slipping. I measured the springs last week when it was apart and they were still factory spec. Any recommendations on after market clutch parts for the added horsepower?

My clutch also started slipping, single cylinder 500cc with gt-15 @15psi. I have read that the barnett carbon plates+HD springs would be a good choice, im going to try it first before the lock-up clutch.

What kind a carb pressurize/pitot system you have? Stock keihin fcr carb?

Ill have to look into those clutches before spring. Who makes locker clutches? Yes I'm still running the stock carb. I just have a pitit tube in the intake tract

My clutch finally started slipping. I measured the springs last week when it was apart and they were still factory spec. Any recommendations on after market clutch parts for the added horsepower?

One option may be a Rekluse Pro. I know it has more clamping force than stock. Not sure about the newer Rekluse exp

I dont know does the yzf has the same clutch with the yfz450´s. There is lock clutch kits available to yammi 450 atv´s.

the parts fich says the only the clutch boss is the same from the yfz to the yz. but i have heard you can put a yz clutch pack in the yfz. so i beleive i could use a yfz locker. I was looking at a Direct Drive CNC locker.. sounds like what i need? I also need to check if the covers are the same, as long as the gaskets match on the parts fich the cool direct drive cover will bolt right up

The direct drive lock out clutch got rid of my clutch slip. Does anyone know how to calculate air flow CFM for a 450? I know it wont be exact because RPM and boost psi will vary... i just need an idea because i am looking at intercoolers.

maybe 100cfm

maybe 100cfm

Maybe not.

If you assume 100% volumetric efficiency at 10,000 RPM, that would be 78 CFM

A very rough rule of thumb is around 1.5cfm per BHP.

The CFM airflow at a given VE for a four-cycle engine is figured like this:

(engine cubic inches)(RPM ÷ 2)(VE% ÷ 100)

--------------------------------------------------------

............................12³

A very rough rule of thumb is around 1.5cfm per BHP.

The CFM airflow at a given VE for a four-cycle engine is figured like this:

(engine cubic inches)(RPM ÷ 2)(VE% ÷ 100)

--------------------------------------------------------

............................12³

^ What he said (same as what I said with more details)

The rough rule HT offers gives 75 CFM @ 50 HP, which is roughly what a stock '06 YZ450 has.

i just pulled a number from the feeling of how a 450 works plus hes got a turbo on there so 78+turbo is about 100

100 cfm is a whopping 28% more than 78, so frankly, it's not even close.

Besides, with supercharging, those numbers are inoperable in any case.

Engine CFM times pressure ratio.

Displacement(ci)*rpm*0.5*Volumetric Efficiency (VE) / 1728 = CFM

You are multiplying by .5 due to the fact it is a 4 stroke, and dividing by 1728 to convert cubic feet to cubic cc's. I have always assumed the miatas VE at 85%. Now you calculate at each RPM desired your CFM.

Oh pressure ratio is 14.7 + boost(psi) / 14.7

So if you happen to be running one bar of boost, or 14.7 psi, it goes like this..

14.7 + 14.7 / 14.7 = 2

Then multiply 2 by whatever cfm number you got in your nifty CFM equation and that is your cfm for that boost and that rpm.

78cfm+boost= more than 78cfm

...multiply 2 by whatever cfm number you got in your nifty CFM equation and that is your cfm for that boost and that rpm.

Not quite as simple as that. Doubling the pressure of air does not double its density, which means that doubling manifold pressure does not double the mass the of air flowing into the engine. Dry air has the following densities at 70 degrees:

14.7 psi: 6.1 cubic feet per pound.

21.7 psi: 4.9 cf3 /lb (7 lb boost)

29.4 psi: 4.07 cf3 /lb (14.7 lb boost, or 2 atm)

So compressing air to 2 atmospheres only puts 1.49 lbs of air in the same 6.1 cubic feet that 1 lb occupied at 14.7. Running 14.7 lbs of boost (which I don't recommend trying) would then increase 78 CFM to the equivalent mass of 116 cf3 of sea level air, not to 156, as doubling would do.

Doesn't the ideal gas law state that density and pressure both double when volume is halved, assuming temperature remains constant? In this case, 14.7psi of boost would provide twice the air mass available compared to no boost, again assuming temperature is constant. :cry:

I know the ideal gas law is most applicable at low pressures, but it wasn't easy to find what distinguishes "low" pressure from "high" where the Van der Waals equation may be more accurate.

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