B6 ?

[muddevil01]

O.K. so I am in the process of preparing for a b6 swap in my 91 GL and I have read a lot about the swap but I still have a couple of questions first of all my swap motor is out of an '88 323. First question I believe the answer to this question to be yes but for the best fuel mileage I use the stock Festiva transmission? Second what kind of fuel mileage can I expect to get I am just looking for an average as I know alot of it depends on driving style. Thanks for any help I am sure these won't be the last questions I'll have while doing this swap.

[iceracerdude]

When I did my swap, it was with the stock festy trans (5 speed), and if I stayed under 60 mph I could average 41 mpg. But that was with the correct b6 ecu: B61K.
The car will run with the B3 ecu, but really comes alive with the B6 ecu.

[muddevil01]

I plan on using the B6 ecu I have the whole car so I can take anything off of it that I need

[skeeters_keeper]

I would use the festiva transmission - lower RPMs on the highway and its much easier.

You can expect high 30's low 40s. Mileage doesn't change too much, from what I've seen maybe a 3mpg average drop from B3 to B6. There are other factors that will affect it more, suspension, tires, pressure, etc.
With my B6 I was getting 38 back and forth to work (driving pretty hard), and got 43-45 on the highway. But I had my front end lowered (less drag) and larger 14" tires (less RPMs) inflated at 44 psi (max sidewall).

[hotfordcat]

My B6 swap gets 38mpg, but I run it hard. 15 miles to work on Interstate.

[iceracerdude]

Yeah, ^ it's a great deal really, a 25% power gain, but without a significant mileage penalty, but don't throw that 323 trans away just yet! If you do start running this thing hard, you know, auto/rallycross etc. You'll want the stronger trans option. Has that Mazda got the 4 speed or the 5 speed trans by the way?

[muddevil01]

It has the 5 speed I was just gonna stick it in the corner of the shop and hang on to it I have also made a deal for a mid-range performance cam for this motor was this a good idea or will I sacrifice too much mpg I am also looking for a header for this motor I got a heck of a deal on the cam I hope it won't kill my mileage

[iceracerdude]

Boy, your really sitting on the fence on this one. You want performance, but not at the risk of mileage...Have you seen the new honda commercial for their "hybrid/performace" car?

I once heard a quote about cars that went something like this: "as far as cheap, fast or reliable goes, you can only pick two"...interestingly, that's been my experience with women too!

[hotfordcat]

Boy, your really sitting on the fence on this one. You want performance, but not at the risk of mileage...Have you seen the new honda commercial for their "hybrid/performace" car?

I once heard a quote about cars that went something like this: "as far as cheap, fast or reliable goes, you can only pick two"...interestingly, that's been my experience with women too!

CHEAP and FAST, right? LOL

[muddevil01]

Yeah I realize that I can't have my cake and eat it too. I know that I will lose mpg when I swap the motor and cam it. I am just trying to figure out what to expect. If I decide that I want better mileage I will drive one of my stock Festivas. I am just trying to build something fun and still be able to afford to drive it daily if I want. This is why I decided to go with the B6 over another swap. So this is what I am trying to do. I figured to be in the mid 30s which I am happy with. My car has a/c and power steering so I figured that with the cam and header I could counter act the loss of horsepower caused by the a/c and p/s

[ShagFestiva]

?

I once heard a quote about cars that went something like this: "as far as cheap, fast or reliable goes, you can only pick two"...interestingly, that's been my experience with women too!

My dad used to tell me that all the time about the wood working industry....its so true!!

[blkfordsedan]

Yeah I realize that I can't have my cake and eat it too. I know that I will lose mpg when I swap the motor and cam it. I am just trying to figure out what to expect. If I decide that I want better mileage I will drive one of my stock Festivas. I am just trying to build something fun and still be able to afford to drive it daily if I want. This is why I decided to go with the B6 over another swap. So this is what I am trying to do. I figured to be in the mid 30s which I am happy with. My car has a/c and power steering so I figured that with the cam and header I could counter act the loss of horsepower caused by the a/c and p/s

I'm doing the same thing with a stock B6. I'm trying to decide if I want to keep the B3 ECU & injectors for now and see what kind of mileage I can get. If I can stay around 45mpg and have a little more power on the highway it would be great. If I can find a good spare B6 head, I'll do some porting on it and put the FMS cam in it. Then next spring I'll swap the head, B6 ECU, injectors and a header. Right now, I just need to get the car going so I can quit driving my F250 to work (100 miles one way).

[muddevil01]

From what I've read you want to use the B6 ecu and injectors because if not the engine won't run the best it can

[blkfordsedan]

From what I've read you want to use the B6 ecu and injectors because if not the engine won't run the best it can

That's true, but many people just used the Festy intake, injectors and ECU on the 1st GEN B3 back in the "early years". It will run fine, just won't be up to it's max potential. I don't have a B6 ECU and the B6 I found has been sitting for a while. I'm guessing the injectors are probably stuck, so for the benefit of time I was just going to use the B3 stuff to start. If the B6 runs good and appears to be in decent mechanical shape, I'll find a B6 ECU and send the B6 injectors out for a rebuild/clean. No point in spending a bunch of money and the time to swap the ECU until I know how the motor turns out!