DOHC B6 Information

[blake4591]

That's a good trick using the B3 rubber bit with the B6 plastic to get enough length. I'm hadn't thought of that but it's going to save some time for sure. I already have the battery mounted between the passenger headlight and engine mount on my car so I have alot of space for the VAM and filter on the driver side.

[Advancedynamix]

Has anyone used a B3 intake tube (Vam to throttle plastic part) with a B6D? I checked on my car and the B3 plastic tube will rub on the B6D valve cover. I was planning to run the capri style intake anyways but I don't think you could use the B3 intake even if you wanted to.

Yes, a few people have used the entire B3 intake tube. I think it does touch the valve cover though.

[Advancedynamix]

William, great idea! I couldn't find a good capri rubber part either, but Russ at Roosport found me a new 323 one that did the job. It's nice having a new one because those things tear at the worst times when they are old and dry.

[UglyEd]

Love all this info on the b6 ive only had my "Steve" for a couple of years its my dd, never put much thought into a motor swap but after reading all this if my b3 ever goes south on me i do believe that a b6 would be a wise decision thanks again for all the info!

Uglyed and the "Steve"

[Team Lightning]

Ed, mine has a B6D, you should love the extra power.

[Dragonhealer]

Has anyone used a B3 intake tube (Vam to throttle plastic part) with a B6D? I checked on my car and the B3 plastic tube will rub on the B6D valve cover. I was planning to run the capri style intake anyways but I don't think you could use the B3 intake even if you wanted to.

Yes, but;
We modified its shape with a heat gun, only to find it wouldn't clear the hood till we lowered the power plant 1/2 inch, which was only possible because the after market swaybar mounts were lower than factory ...

We kept all the B3 engine management, including injectors. The wiring wasn't too bad, but the hosing was inelegant to say the least...used Capri intake and exhaust manifolds, modified the rest to suite. By far the cheapest way to swap.

[UglyEd]

Im sure i would seeing as mine has nooo power but its the mpg im after, i know somewhere i saw someone talk about a b6 that was carbed im old school thats probly the direction i would go seeing as mine is an 89 with an escort carb no ecm with a 4spd gettin 45 pretty regularly, does a b6 still get that good??

Uglyed and the Steve

[william]

I average about 40 with my b6d it had low compression after the rebuild though.
And that's at 70 mph it's gotten better and can certainly get worse
That's with the factory 5 speed and 165/55/14's on light wheels.
Its also ran on capri electronics. Rather than the festiva stuff. At the time I did my swap I didn't know anyone who had done it besides shade tree he told me to use the capri harness because I had the whole car . Its easy to wire up and has been a great swap this engine should have been in the festiva from day 1.

[errjam]

capri harness vs festy harness I have a 93 festy with a 92 auto capri complete car.......

[Dragonhealer]

Im sure i would seeing as mine has nooo power but its the mpg im after, i know somewhere i saw someone talk about a b6 that was carbed im old school thats probly the direction i would go seeing as mine is an 89 with an escort carb no ecm with a 4spd gettin 45 pretty regularly, does a b6 still get that good??

Uglyed and the Steve

No change in mileage after the swap, just WAY more power '92 with auto

[Advancedynamix]

I've gotten around 40mpg with my b6d on occasion, but mostly I'm in the mid 30's. I drive spirited wherever I go though, so it's pretty similar to a b3. The SOHC b6 may be a better choice for someone wanting to retain the stock b3 mileage. You can bolt all the b3 parts to the first generation b6 and simply have a slightly larger displacement.

[blake4591]

capri harness vs festy harness I have a 93 festy with a 92 auto capri complete car.......

I used a 93 festiva harness saves most of the wiring. This method probably gives up a little performance but its the simplest.

[Advancedynamix]

We are trying to get a back to back Dyno comparison of the B3 management VS. Capri, but things have been getting in the way of getting the b6d/b3 swap finished. We have dyno results from Dragonhealers b6d/b3 swap. However, that isn't a good comparison. He had really low compression in one of the cylinders of that engine. He just tossed in a junk miata core engine to replace the b3 that grenaded on him, so that the car could be driven. Also, that car was an automatic. I think it still made like 90hp to the wheels though. I'll try to find the dyno sheets from that.

[blake4591]

I think a BP distributor would work, as in physically bolt up, but I haven't checked the signals that the distributor is sending out. There could be some internal parts swapping required to get everything working. I don't have a spare BP distributor but I'll keep my eye out for one to try some things with.

I have confirmed this. BP distributor bolts to b6d, plugs directly into the festiva harness and seems to cause 0 problems with the festiva ECU. I actually looked into it and the distributor is really only a magnetic pick up that tells the ECU the engine is turning.

[Advancedynamix]

That's great information! This makes the b6d swap even more of a simple plug and play deal. Thanks for checking that!