Lewis Maudlin Posted March 16, 2005 Share Posted March 16, 2005 I am planning on building again. My last Z was a 355sbc with about 400hp and a Raptor 700R4. The car was great, had air, but just drank too much gas. I only got about 12 mpg. I enjoy driving my Z too much to have that kind of mileage. I am thinking about going GNZ or L28et. Which do you guys think would be easiest? Which would be cheaper? Which would get better gas mileage? I am pretty sure the GNZ would put more power to the road, but I would be happy with 300rwhp. I can get that out of either. My current Z has the L28 with Tokico's, a clutch upgrade, a 5-spd and is rust free. Any pros or cons? I am not the best mechanic and I don't plan on starting until 2006. I am just driving my Z this year. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 16, 2005 Share Posted March 16, 2005 Well, the l28et is easier to do thats for sure. Quote Link to comment Share on other sites More sharing options...
Dead Roman Posted March 16, 2005 Share Posted March 16, 2005 if your going to build up a performance motor, and you still want goo gas mileage, go with the ls1 or sr20det swap. Quote Link to comment Share on other sites More sharing options...
Dnaught14 Posted March 16, 2005 Share Posted March 16, 2005 the gnz will be more expensive. I love the swap, but i also love manual trans, something you cant have in a gnz. It just doenst blend well with the 3.8. If your looking for simple the l28et is your best bet. Ya, it wont generate as much power as the gn, but 300 can be achieved with a t3/t4, an intercooler, a bov, 3 in exaust and downpipe, better fuel pump, bigger injectors-good to have, and possibly an upgrade to the fuel system. I know it seems like a lot, but it all bolts on and can be had for under 3 grand. Buy the engine and start bolting things on. thats my .02. I do love the gnz though. Brad Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 16, 2005 Share Posted March 16, 2005 Tough one. I like the tunability of the stock GN motor to get great power, but I'd want a manual trans. I believe it's been done before. Just need a flywheel and adapter plate I'd think, with like a T-56. A 400hp SBC shouldn't have to get 12 mpg. What was the build like, the gears, etc.? My 327 Z goes 110mph in the quarter, which works out to around 375hp, using my car's corner scaled weight of 2800 with my 200+ lbs in it. I get 23mpg on the highway. But that's with a 3.7 diff, 5spd with .68:1 overdrive, and 26 in tire running a 650 double pumper (that's the mileage I got going to/from the SEZ 1 with the carb). My vote is to research the GN swap with a manual trans. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 16, 2005 Share Posted March 16, 2005 If those were my two choices and horsepower goals, I would have to decide on either an automatic or manual tranny. If I wanted an automatic, then the GN would be my choice. On the other hand, if I wanted to stay manual, the L28et would win out. Either way, properly tuned with a decent gear ratio (you'll probably end up w/ a 3.54 rear gear), you'll get atleast 25-26 mpg highway and 20-21 mpg city realisticly. Quote Link to comment Share on other sites More sharing options...
quicker240 Posted March 16, 2005 Share Posted March 16, 2005 I think your issue may stem from another source.Theres a pedal in the footwell that if you push way far down on a regular basis,will cause a multitude of problems.Rapid tire wear,poor gas mileage,elevated repair costs,all of which tend to cause lightening of the wallet.The GNZ or the L28ET,as well as the 355sbc w/700r4 all will give similar problems.I reccomend a stiff diet of boring driving habits.By far the cheapest way to arrive at your mileage goals. Quote Link to comment Share on other sites More sharing options...
slownrusty Posted March 16, 2005 Share Posted March 16, 2005 That is really an "apples and oranges" comparisson. The GNZ has far more power potential than the L28ET, more displacement really helps here too. It all depends on how much fabrication you want to get into and how deep your pockets are. Remember "Speed is an addiction that can only be cured bt poverty" Yasin Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted March 16, 2005 Author Share Posted March 16, 2005 Yes, I had pedal problems with my 355 sbc. That may be why I got 12 mpg. The pedal on the right kept telling me to push a little harder. Thanks for the info. Lewis. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 16, 2005 Share Posted March 16, 2005 If 300rwhp is what you will settle for, then go with an L28ET with the right components. Will it be easier than the GNZ? Yes. Will it be cheaper? Questionable. Depends on the condition of the drivetrain and the components you get to make 300 (remember we are talking RWHP). The entry fee on a GNZ will always be a little more but if the goal is way beyond 300rwhp then it is the better choice as it take pennies to make 300-350rwhp. Will the L28ET be as economical? It could, but it will take the right components, a lot of tuning, and as quicker240 said, driver discipline. Fiddling with the AFM, cold start valves, cranking up the FPR, running 18+psi boost on the stock turbo, etc, are all cheap ways to get the magical 300hp but will not get you everything else you want. Speed cost money and it is really hard to get speed/power, cheap, easy and gas ecomony all at once. BTW, ponder this thought. 300rwhp in a turbo car will not be enough. Trust me on this. Once you go beyond that, the econimics get a lot more interesting. Quote Link to comment Share on other sites More sharing options...
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