Loserkidwac

Can I play? I should post my build on here...but i didn't think anyone would car lol...I swaped an auto Del Sol S to a VX D15z1 and trans...I get 50mpg on the Highway and 40mpg with city driving...an I have a targa top :-P

onlyflash944

But Bone, I WANT a theoretical top speed of 220


You keep saying this, is it you are worried that the fuel consumption will be greater cruising in 5th than in 4th? I understand the concern that at that low of an RPM the efficiency takes a ----, but I want to see exactly what the difference is. I was planning on doing a test in 4th only then one in 5th. Then add something to increase the effective compression ratio and see the difference. Of course making boost at 2k might be a challenge.

Jorsher

I wish valves were electronically controlled instead of mechanical... I understand mechanical is a bit more reliable than electronic, but theoretically if valves were controlled by the ECU (---- vtack), wouldn't you be able to maximize efficiency? Also, while cruising, I'd *guess* you'd be able to keep the exhaust/intake valves open and cut the fuel to some of the cylinders and not lose as much power due to compression.

onlyflash944

Great ideas and yes if you were able to change the valve timing and lift continuously, then you could definitely pick up some efficiency. However, I would imagine the displacement on demand is geared more toward the big v-8 boys instead of the 4 bangers. I’m not sure how well that would work, but it would be neat to try.

Jorsher

Every little bit helps. I doubt I need all 4 cylinders going down the interstate at 4000rpm. Definitely wouldn't be as helpful as using that on v8s, however I directed it at engines in general not any specific size or displacement.

beaker

if im not mistaking.....new bmw's already have continuous variable valve timing

Jorsher

If they came out with VTEC for the NSX, I hope they come out with some continuously variable valve timing on the new one.

Hitchhikkr

Its existed for a long time. But just like every technology in the automotive industry, it will be years more before its implemented, IE before its profitable for auto companies to invest in. Pneumatic valves are faster though.





Once again, old tech. But 17,000rpms is FTW.



----, buick invented variable valve timing in the 1920's. Now damn near every mid-high end car on the market has it. *** ur vtak. :P

onlyflash944

Just fyi, 70mph with my gear setup is 2200rpm in 5th, 2700rpm in 4th. This is with 195 60 14s, and that might change. I might undersize the tires a bit to help get the rpms up and reduce the unsprung weight. I'm just going to have to do some research and see how that will change the rolling resistance. I've got a nice selection of 14s from all the cars/wheels i've bought so I should have something that will be useful lying around. Might see about some 13s too.

Guy-Fast

Im a little suspect of your transmission choice. jdm d15b non vtec originally dual carb motor w/ d16z6 manifold set up and si transmission was in mid 40's on a stock pm6 ecu. Car ran like total ---- with the origninal hf transmission o2 sensor codes that went away with the change to the si transmission. Also driveability with the si transmission made it worth driving. hf was a waste. Gas mileage is one thing having a car that is slower than a mini van is another.