I was pondering a conversion such as this one for my 914.....what MPG could i expect?

You ponder so many projects Britt!! I would love to visit your garage after you win the lottery.

i know....i'm still trying to strike it rich....one lotto ticket at a time...i think i might just do a suby 2.5 conversion...with a Megasquirt

Britt, one project at a time. first a new motor, then a Westy, now a V-8. Are you a little compulsive? Yep, you need to win the lottery(who doesn't?).

I can tell you what it is: he is a first year in college. They have SOOOO much free time. Dont worry, you'll notice in a couple of months he'll take some real classes and wont post any more (like myself)

its really that i work for peanuts in a gov't campus job....

By very wild cam... What do you mean?
I have a mildish cam... 2.2k-7k... (maybe it was 6.5k... cant remember)
Cam lag is HORIBLE (just kidding... In comparison to when the cam hits, its like 1/2 the power.... lol)


I expect to get 20+ mpg highway when I go with FI.
city should be 15ish.
All depends on how you drive... lol

There have been claims of 25.. 30 and 33 I think..

With SO much torque, it takes like a feather on the throttle to maintain 65 on the freeway. A different gear in 5th, such as an H gear... that could bring it down to 2.2k would allow for a much better MPG..

The reason i said V8 is from simplicity's sake....i think i might just do a suby conversion...besides it might get better milage anyway......i was going to use a mesasquirt on whatever i got...bc i am personally not a carb fan...(never had one tho)

He is just trying to keep his post count high, how else would he have almost 1000 posts since January? Rod Simpson claims he gets 330 HP with 30 MPG+ with his cam setup and I followed his exact specs on my engine. Once I get it on the road and get to drive it a lot, I will check mine.

Rod Simpsons cam is based on the miller cycle.

I am skeptical of a 30+mpg V8 conversion. I'd be very impressed to see one at 25. 20 is do-able, but you probably need to change your overall gearing. I haven't seen 15 during break-in with close to stock gearing (2750 rpm @ 70 mph). The car's getting dyno tuned right now, valve adjust, distributor re-curve, carb jetting. There had better be some mileage improvement but it's not going to double...

I'll be going with taller tires after my flares, 205/50x15 now, probably go to 255/50x16, an increase of about 13%.

Anybody else got actual mileage numbers on a V8 conversion?

That said... YMMV

Eric

QUOTE (Type 4 @ Apr 6 2005, 02:28 PM)

Rod Simpsons cam is based on the miller cycle.

I'd be fairly surprised if that's actually true, unless all of Rod Simpson's kits come with a supercharger.

The Miller Cycle is a bit of hocus-pocus that requires a very high static compression ratio, then uses very long intake cam duration to lower the dynamic compression ratio to a reasonable level. The only way this works w/o just blowing most of the intake charge out the open valve is a supercharger, which keeps manifold pressure high enough that the charge can't escape. Supporters of the system claim an efficiency increase of 15%. It was patented in the 1940s, and largely ignored.

Mazda tried it on the Millenia (well after the patent expired). Fuel economy and power figures for that car aren't exactly startling (28/17, 210hp, 2.5L supercharged V6). It didn't necessarily flop, but no one else has expressed any interest in the idea.

QUOTE (ewdysar @ Apr 6 2005, 02:32 PM)

I haven't seen 15 during break-in with close to stock gearing (2750 rpm @ 70 mph).

I got almost 19 miles per gallon on my mild built 350, stock gearing, doing about 3300-3500 rpm from SoCal to Vegas and back. The H-gear rebuild should make a huge difference. Weight isn't an issue, I brought enough tools with me to completely rebuild the car on the road, but that wasn't needed. Plus food and clothes to live off of for a little while.

I can get up to 15 in town, but usually 10-13 due to my love of the car's power to weight ratio and stand on it from the red lights!

FI shouldn't make a huge difference, about the same as getting dyno tuned I guess.

Eric, have you gotten your car to build up to full 180 degree operating temp?

My father has an LS1 Trans Am with a 6 speed. he says he gets high 20's on the highway - but that 6th gear is very overdriven. It is barely idling hauling ass down the freeway. If I had a car like that, I'd flat out be writing this from jail.

see thats what i want....like a super-H 6th gear.....that would be super cool.

QUOTE (bd1308 @ Apr 6 2005, 12:16 PM)

I was pondering a conversion such as this one for my 914.....what MPG could i expect?

Learn to werk on the 914 first, finish school and get a well paying job, pay someone else to do it for you! How in the hell are you going to pay for EITHER of those conversions when you can't even afford to have your 2.0 heads rebuilt???
It's nice to see that you're so gung ho about your new car but damnit your TOO gung-ho. For cryin out loud, go get a Haynes manual and learn to werk on a simple, pre made car and enjoy it as the factory intended.

Ian,

Yes, my enginge warms up now. The T-stat from RH had 3 by-pass holes drilled in it, I calculated them out to about 20% total flow while the t-stat was closed. I put in another with 5% bypass holes in it (I was chicken) and the car warms up reasonably quick now. The engine stays around 180 now, the fans come on at 185, I don't think that the engine has hit 190 yet, but summer's coming. Even now, in 75 deg weather the t-stat is spending some time closed (you can see the fluctuations in the gauge)

I realized that the heater core is plumbed off of the manifold, so it flows even if the t-stat was sealed. I'd like to find a valve that would route the manifold flow to either the heater core or another hose leading to the back of the waterpump. This would provide some flow to protect the impellor from cavitation while cold, but shouldn't degrade the radiator flow much (at all?). I'm going to check how the engine acts in the summer heat before adding the extra plumbing. Maybe just use the heater flow valve, the red lever on the tunnel, to act as a manual bypass control, open when cold, close it after the car warms up. When I get comfortable with the bypass setup, I'm going to change to a full stock t-stat (no holes) for quicker warm-ups.

Eric

The holes in the t-stat are to let the air bubbles out of the system so don't eliminate it! I'm running a pin hole in mine (1/32") and it does fine.

Off topic car wise. I just bought a Land Rover Discovery and what I can't figure out is why I only get 11 mpg in town and sometimes 9!! The dang thing only has a 3.9 V8, but the car does weigh in at 4800lbs. I wonder if I can make an H gear fit.

Ian,

The t-stat that I modified and installed has a manufactured crimp along the edge to prevent a perfect seal. I'll have to check the tiny gap size when I'm home, maybe it's around 1/32". You think that might be enough? Are you running a heater?

Eric

I'm doing a V8, and mileage is the least of my concerns. I'm not sure how many guys use their V8's as daily drivers because the whole concept seems to be more about the week-end fun car, or periodic stress relief. If your concerned about MPG (and maybe you should be considering fuel prices), you should look closer at smaller displacement conversions.

well i'm trying to get a 1.7 T-IV going....but i like muscle sometimes, i was just wonderin...