with a good tune/set of 3400 heads, 2.8=good mpg?

[no_doz]

on saturday im going to pick up my new (new to me) 88 z24 convertible 5 speed, & ive been reading reviews about it and they havent stated anything good about the gas mileage, but then again i dont intend to leave this stock for very long. i intend to get a chip tuned by ben & use a set of portmatched & very mildly ported set of 98+ 3400 (preferably 2k1+ but who knows) heads & for now the stock 3400 intake manifold & custom headers, with these modifications & a good tune, could i see great gas mileage out of this engine or honestly for both power/gas mileage purposes would i be better off to just swap in a 3100 or 3400? id really like to see 35 mpg on the highway with this 2.8 & i dont figure thats too unreasonable, but what do you guys think?

i like the whole idea of the short stroke & generally small displacement, but is there really that much difference in gas mileage between the 2.8 & 3.1, because every aluminum head 3.1 ive ever had has been a gas mileage champion & given me about 29-30mpg on highway when driven properly, will the 2.8 be that much better on gas or is it not worth it at all?

[robertisaar]

2.8s will already be pretty good on gas, assuming they were taken care of....

and most of their torque/power is in the low-rpms anyway, so it should be alright.

swapping in a 3400/3500 hybrid wouldn't hurt it too much though, and with much more power as well. its when you start camming them, hogging out the ports to the point of ridiculous is when you'll lose fuel economy. also gearing will have a LOT to do with it to.

[asylummotorsports]

The 2.8 and 3.1 are essentially the same engine. Argue all you want.

35 mpg? Maybe with a 5 speed and you keep your foot out of it.

You start swapping stuff and all hell breaks loose as far as mileage is concerned, but 35 is likely out of the question because you WILL NOT "keep your foot out of it!"

[no_doz]

it does have a 5 speed and its in a light little cavalier-if i had to go on a long trip & wanted to set cruise (if it has it) or just cruise at the right rpm-if i have the chip programmed for best economy in that rpm range do you think 35 is possible with a 2.8?

and i realize that the 2.8 and 3.1 fwds are the same with the exception of crank & rods (if im not mistaken)-but is that .3 really that much to gas mileage, or are we talking like a 1.5mpg difference in the end?

[robertisaar]

possible, yes

probable, IDK, depends on way too many variables...

[asylummotorsports]

A Cavy convert is not all that light relative to a coupe.

And that is why the Beretta Convert didn't make it to production. They crumbled like a Saltine into Tomato Soup!

But 35 mpg is a possibility.

To be honest you are posing this to the wrong guy and I will get out of this thread.

I DON'T CARE what mileage I get. It's just time slips to me..
Have fun with it though. They are cute cars.

I saw a couple of nice ones at the recent J-Body Event up here and they both really caught my attention!

[johnnymossville]

I took my '93 Lumina Euro sedan with a 3.1 on a 430 mi road trip running between 75-80 mph and averaged 31.9 mpg. It had a K&N drop in air filter and a Z34 dual muffler exh. with Dynomax Super Turbo muffs and no cat. If you treat a 3.1 right it will last a long time and get good mpg. Now a 3400 with p&p 3500 heads, uim, lim, 65mm tb, 11.5:1 cr, and a .531 lift cam is another story. I didn't have it fully tuned while it was in the Corsica and I only got around 22 mpg but it is so much fun I could not keep my foot out of it.

[robertisaar]

compression will help fuel economy, the 8.8:1 that a 2.8 has is LOW. 3100s has ~9.5:1, and were perfectly fine on 87...

[no_doz]

this convertible is, because its a manual top & theres like nothing to it-it weighs a tad under 2700lbs with the 2.8 & 5 speed