LS4 / F40 swap - fieroguru (Page 31/216) dobey SEP 03, 11:01 PM quote Originally posted by Syn: That is a good looking motor! actually all your motors look good. and by they way your button head bolts on that motor look fantastic would have never thought of that. I think that if you could get enough rotational mass(which you are doing a great job of that right now) that you would actually see better fuel mileage at highway speeds, since the average is 5-7.5%. if you got 23 MPG you would get around 25 MPG. I mean that is an extra 32 miles per tank but I think your actual gas mileage numbers are going to be quite a bit better than that since its going in a car that fully dressed was about 1000 pounds lighter. but what am I telling you this for I'm sure you already know all that So far, the stock LS4 swaps with the 4t65e-HD seem to be getting about 28-30 MPG on highway. So hopefully fieroguru will be getting at least that. Although, with that enormous cam, he may very likely not. Also not sure what tires he plans on running, but a taller tire will help bring the RPMs down a little. I'll be trying to get 35+ MPG out of mine; without the AFM. Syn SEP 04, 09:48 AM quote Originally posted by dobey: So far, the stock LS4 swaps with the 4t65e-HD seem to be getting about 28-30 MPG on highway. So hopefully fieroguru will be getting at least that. Although, with that enormous cam, he may very likely not. Also not sure what tires he plans on running, but a taller tire will help bring the RPMs down a little. I'll be trying to get 35+ MPG out of mine; without the AFM. yeah, I was using stock numbers in a 3700 pound Impala, just the sheer loss of weight overall and rotational mass I imagine he would get around 25-27 with out DoD so that would be about almost 30 mpg at 7.5% but these figures don't really mean much since it's purely estimation and doesn't take into account the 6 speed cruising Fieroguru is wanting to achieve and like you said tire height will play a role in getting the RPM's down. I don't think 35 would be a unachievable goal, but there is no better way to prove math then by testing it in the real world! Can't wait to see it running and driving. Syn fieroguru SEP 04, 10:15 AM My blue fiero has always ran 245/45/16's which are 24.6" in diameter, but I really need more tire on the rear. Eventually, I will stuff as wide a wheel back there and probably upgrade to some 17's or 18's in the rear to help further reduce the cruise RPM. I would love to see 35 mpg with my combo, but would be happy with anything over 30, especially at the whp my combo should produce. The cam is a little on the large side, but given I am targeting a 2850 vehicle weight with the swap, the low gearing in the transmission, minimal frictional losses within the transmission and the smaller frontal area on the fiero, I think it will be just fine. One guy is running the same cam in a Grand Prix and it can still pull itself with DoD turning less RPMs, with taller tires, more weight, more frontal area, and more parasitic transmission losses than I will have. You guys are getting me all excited to get back to work on this swap, but the 383/Getrag combo must be done first and it is my priority. Syn SEP 04, 11:10 AM quote Originally posted by fieroguru: You guys are getting me all excited to get back to work on this swap, but the 383/Getrag combo must be done first and it is my priority. I'd offer to come help you hurry up and get it finished so you could get back on the ls4/f40 but your in Kentucky Speaking of the cam that you have though, did they give you some torque numbers? no so much max torque but just where it is in the power band? Syn dobey SEP 04, 11:56 AM quote Originally posted by fieroguru: You guys are getting me all excited to get back to work on this swap, but the 383/Getrag combo must be done first and it is my priority. Haha. Better get that 383 done then! I just got my heads milled, a valve job, and crank cleaned and polished. I need to do some yard work (yay hurricanes) and pick up a few things at HF, but hope to get the block cleaned, and short block back together today/tomorrow. dobey SEP 05, 05:16 PM I guess I have to take that back. Yard work more tedious than I thought it would be, and seather is being finicky today. Most likely will get to it next weekend, or hopefully find time one night this week. fieroguru SEP 05, 06:59 PM quote Originally posted by dobey: I guess I have to take that back. Yard work more tedious than I thought it would be, and seather is being finicky today. Most likely will get to it next weekend, or hopefully find time one night this week. That is one of the best things about my current garage... even on 97 degree days (like it was on Saturday) it stays about 75 and on days under 30 degree it stays about 65... as long as I keep the rollup doors shut. I spent the day making braided stainless hoses with AN lines. In a day or two, the engine/transmission/cradle will come out one last time to finish up the engine bay detailing firewall insulation. Then I need to finish up the harness and the rear merge/muffler area of the exhaust: With stainless heat shields added: dobey SEP 05, 07:25 PM quote Originally posted by fieroguru: That is one of the best things about my current garage... even on 97 degree days (like it was on Saturday) it stays about 75 and on days under 30 degree it stays about 65... as long as I keep the rollup doors shut Yeah, the heat wasn't too bad today, but some small rain storms came through. Don't have a lot of room in my garage as it is right now, so would have to pull the car out to work, and don't want to leave it sitting out in the rain. The other necessary chores are the bigger damper though. That 383 is looking good too. Syn SEP 06, 11:13 PM was reading some on someone who put a ls4 in their Fiero and it brought up an interesting question, What do you plan to do for the interior? adapting the Fiero interior to accept the new components? or using a newer model dash out of something like a Malibu, Impala, or G6? fieroguru SEP 07, 12:32 PM quote Originally posted by Syn: was reading some on someone who put a ls4 in their Fiero and it brought up an interesting question, What do you plan to do for the interior? adapting the Fiero interior to accept the new components? or using a newer model dash out of something like a Malibu, Impala, or G6? Nothing in the interior "must" change to run the LS4 besides adding the electronic throttle pedal. You can add as much from the donor car as you would like, but it isn't a requirement for the swap. For now my fiero interior will remain stockish. A longer term project is to swap out the dash from a 1999 maxima (my wifes car and I like the dash).