getting better mileage out of a 450hp car :)
 

Well a 25 cent part is broke in my metro trans. Going to have to take it out and split the case to get at it though :( Meanwhile I get to drive my drag car to work. 2002 Camaro Z28, ls6 block, GM ASA racing cam, 3000 stall converter, wide open exhaust, and lots of other stuff that doesn't do much other than run real good 1/4 mile at a time.

So the car stock would run a 13.08 1/4 mile and get 25 city 31 highway. Currently it can run anywhere from 11.6 to 12.3 depending on traction and I typically get just under 10mpg driving to the track racing all day and driving home. I drove it to work today trying to be easy on it and managed 14mpg. But it is a lot different than a metro doing a lot of stuff. It does not require any extra throttle to hold speed going up any hill is the first thing. Taking all curves at full speed with no braking is another helpful advantage. Before I left for work today I reset the L-trim tables and set the torque converter lockup to 45mph, 35mph in 3rd gear. I also am thinking of setting the target voltage on the O2 sensor to .3 or so to lean it out a bit but I am not sure if the 110 degree lobe separation cam even lets the O2 sensor properly work. The cam has a big overlap and lets plenty of intake air out the exhaust. It is impossible to stand near the back of the car with it idling due to the fumes. 226/236 int/exh @ 0.05" duration 0.525" / 0.525" int/exh lift 110 LSA are the cam specs. Also I wonder how much extra drag I get from driving with drag radials on the road.

So anyone got any ideas for experiments I can try on my 100 mile round trip to work the rest of this week? I am not thinking there is much to be tested but it could be interesting seeing what I can try in it.

I would say that for how much you are going to spend on gas in a week, you could almost replace the cam with something more reasonable, and that alone should help a great deal.

I'll probably have the metro back on the road friday after work so I don't think there is much point in trying to swap cams or the torque converter just for a few days of driving. I might do a few simple tests if it is warm enough friday like seeing how much difference there is with the windows down and tops out compared to the car being closed up. I figure I don't really have much time to do any major tests but I'm just trying to have some fun with what I have without having to get any more speeding tickets fixed. I am thinking tomorrow to run the car with 45psi in the tires to see if it is different than todays tire pressure of 40psi front, 28psi rear I normally run.

Try testing tire pressure. My theory is that the rolling resistance of typical drag radials isn't that different from standard street tires once they're pumped up hard.
Edit: doh! you beat me to it!

I'd like to see if higher rpms yields better FE since you have a big cam in it. There may be a point of diminishing returns as rpms go lower. For example, does 1000 rpm give worse FE than 1500 rpm?

How many miles can you cover before you give in to the lure of big HP and floor it? Can you restrain yourself and drive a full day at Metro speeds/accelleration in your drag monster? :) See what that does to your FE?

Coyote X: So anyone got any ideas for experiments I can try on my 100 mile round trip to work the rest of this week? I am not thinking there is much to be tested but it could be interesting seeing what I can try in it.



If you have a means to change your centrifugal advance, do this. I have removed the springs from the centrifugal advance weights in the distributor. This allows full advance constantly. Using lighter springs or only one spring does the same to a lesser degree. Under light throttle, low load conditions this will cause no ill effects. You retain the total advance as before.

With a big camshaft and low vacuum, your cylinders are just loaded with too much fuel. More low RPM advance will alleviate some of this and make the engine smoother, more responsive and burn cleaner. Let us know if this helps.

Replace the high rpm cam with a low rpm (torque) grind, and take out that automatic transmission with its ridiculous 3000 rpm stall torque converter, and in its place install a manual tranny.............

This will probably just reveal my ignorance about exhaust theory: but would constricting the flow / increasing back pressure help to get more fuel burned at low RPM? That would be an easy mod (sticking something on the end of the pipes).

From what I've read of your post and background, just do the basic setup (inflate tires, keep it light, keep it aero, etc.) and stick to FE driving techniques so you can spend the time getting your XFi fixed ASAP. If you can afford a few extra minutes on your commute, you can make some big gains by spending them in the right places.

One example is if you come up behind a truck that's only a bit slower than your normal cruising speed, draft it for a while. Also, when you come up behind somebody, instead of passing them right away, you could shift into neutral and coast into and then out of their draft, accelerate into their draft, then coast down in neutral from your passing speed to cruising.

WOT and pussyfooting are both bad for FE; keep it somewhere in between and use the brakes as little as is practical.

The best info on techniques:

https://www.cleanmpg.com/forums/artic...mile-1510.html

I didn't think about sticking something in the exhaust but that might help control some of the overlap in the cam. I might give it a shot tomorrow. I set the tire pressure to 45 front and 40 rear. The rear tires have a max rated pressure of 32psi so I didn't want to go much over it, they are pretty expensive tires so I don't really want to blow one of them out. One thing that does suprise me is how much better the mileage is than I would expect. I drove 70mph cruise control with the old tire pressure and managed 19mpg. I will find out what the higher pressure gets me then I might try plugging the exhaust pipes partially and maybe try driving with the rpms below 2000. I pretty much will only drive the car tomorrow then I will be back to the metro but it was kind of interesting that I can still manage 20mpg in a car that can run 11 second quarter miles :) It might be kind of fun doing some more experiments later with this car so I might drive it some here and there but, it would be a pretty expensive car to do tests on. 300$ per tire that gets about 5000 miles of life, starter motor and IAC stepper motor don't live long due to it not being able to idle well, not to mention the land sickness you get from driving a car for long periods that shakes as bad as this one does.

As far as the ignition timing when I dyno tuned the car I advanced the cam timing a huge amount on the bottom end to make the car even able to idle under 1000rpm. I know the car has practially no power under 2000rpm and yesterday when I was driving it I tried keeping the torque converter locked up as much as possible and always shifted down to keep the engine around 2000 and downshifted to avoid running under 1500rpms if possible.

Do you have another set of tires you can put on the car?
I run Toyo T1R set at 50 psi for daily driving.
You also might want to see if you can do any aero improvements, such as an under tray.

I know several people that dumped the N/A LS1 and went turbo. This can make a huge difference in highway MPG and HP level.

I should be low 11s to high 10s this year (V6 Turbo w/ automatic). I am shouting for 40 mpg at 65 mpg on the interstate. I am concentrating on tuning and aero mods.

https://www.gassavers.org/gaslog/chart.php?id=159

went ahead and filled up tonight instead of waiting till morning and I managed to get 22 mpg :) I am suprised I am so close to my stock mileage. I guess the tire pressure helps even though it makes it wander real bad on the road, no front sway bar on the car so that doesn't help either. I am thinking some of the gain from today was from getting used to driving it carefully and keeping the torque converter locked and the engine over 2000rpm all the time.

Tomorrow is my last day to test something so I figured I would go for plugging the tail pipes halfway to add some restriction and maybe eliminate the scavenging the exhaust does. I don't know if it will really change much with the long tube headers on the car but I probably won't drive it much again till spring or when spring is supposed to start anyway so this will be my last test on it. It was fun while it lasted but after tomorrow I will have spent $100 in gas just to drive to work for one week so this car is a bit hard on my wallet to do much testing with.

How about some results on plugging the exhaust. Rotten results are just as informative as good ones.

I made some caps out of roofing tin to go over the square tips on the exhaust for that last day with a 1 inch hole so it was pretty restricted. I put them in place with duct tape. I figured it would be good enough to get me there but they were both gone when I got to work and I did not find them on the way home so I have no idea where they came off at. The last day I got the same mileage I just forgot to put it in my gas log.

My metro is running again so now it is time put the Camaro back up on jack stands for the rest of the winter :)

Hmm, i used popcans on my V-8 Monster (but it only generates about 150 hp, on a GREAT day) I also bolted mine in so they coudln't blow out. and they're still surviving fine.

I find the difference between an 11 second pure drag car, and a (high) 12 second street car to be amazing. We share the high overlap race camshaft, however mine only kicks in above 4500 rpm where it generates more power than the polite, gas sipping, little cam. I'm also open exhaust, unless you count the turbo which does a great job of quieting the car down, quieter than the Lincoln with it's small exhuast leaks.

Ever consider turbo'ing the Camaro? I bet you could get it right back up to 30 mpg highway, get the same drag times, and have a MUCH more useable power band. I can't imagine street driving something like yours :thumbup: to you for doing it though!

I could turbo or supercharge it and get it much faster than it is now. The main reason I run it all motor is reliability and consistency. I know the car will last with its current setup easily 100k miles with no trouble other than the stock 4l60e trans not living much longer, it will be beefed up to handle the power this spring so that is not really a problem. The car is also very consistent at the track. When it was stock its times varied by .2-.5 seconds from one pass to another so it made dialing it in not much more than a wild guess. Now I can dial it in close since it is usually within .01-.03 between runs. I don't run a box so I think that is pretty good for a car that I drive to the track.

I don't drive the car much other than for cruising and racing so I don't mind a bad idle and the car dying at every other stop light if I don't watch the rpms. If I had to drive it more often I would have probably left it stock. I have it set up as a very fun to drive car now. It sounds real mean and has enough power to go faster than most street cars and since I only put at most 1000 miles a year on it will never wear out :) I don't think the car is that bad to drive though it is much smoother than my kit car. That one is a 2100lb car with a 500ci motor sitting on the back tires. That car is a handful to drive, it can pull a wheelie up to 120mph and I have not been able to get a good 0-60 number but it is realistically under 2 seconds. It handles ok and brakes ok but it has 800lb springs on the back and 400lb on the front so you can feel every crack in the road. I thought about getting a kidney belt when driving that car.

" and the car dying at every other stop light if I don't watch the rpms."

You have an 'auto-stall feature'!
It's great for eoc. :)
Your car sounds badass. :thumbup: Reminds me of my other car. It has somewhere over 450hp, hard to drive, sucks up the gas, stiff as a brick. When it's time for some real fun I wouldn't have it any other way. It scares me a little sometimes, which is just how I like it!

I'd be curious to see how it runs if you can drive 55 MPH for a tankful, then switch to 70 MPH for a tankful.

What kind of kit car? Sounds like something I'd like to build!

Before I modified the car I have drove it cruise control constant speed for long periods of time and under 80mph doesn't really change the mileage much. I figure since th engine was turning 1900rpm at 70mph and the car is pretty aerodynamic there is not much difference between 55 and 70. Maybe one day I will get a scangauge and find out but I really don't think it is as big of a change as a smaller engine car.

As far as the kit car check out https://mantaproject.com to see everything I ever did to the car :)

https://mantaproject.com/restore/2002-06-22/IMAGE003.JPG

Tons more pictures and stuff on the website.

Manta Montage!


Dude, I love that body. I wanted one to convert to an EV long before I found the Triumph, but I just could not find any, let alone find one for an affordable price! Must be a joy to drive with that Cadillac 500 engine...

Wow! I've actually already looked at that site a few times!! Very impressive car! I can't imagine driving that thing, has to be an absolute blast.

https://cgi.ebay.com/ebaymotors/Repli...spagenameZWDVW

If you want a montage you better have cash ready and hit buy it now, that one wont last long at that buy it now price :)

whew, waaay out of my price range. I'm more in the market for a sport bike at this point in my life.