DOHC to B6T swap questions

[jimgreenlee]

I am going to be swapping over to a B6T engine from my DOHC here in a few weeks. I have been reading a lot about the swap, but almost all posts are for a SOHC to B6T swap. Just wondering who out their has swapped from the DOHC to B6T. Also I was wondering what parts are necessary immediately for the engine swap and what parts I can add later. I read that I don't need the RX-7 MAF because I have the DOHC engine, and want to make sure this is right. Also I am only planning on running low psi at first around 7 or below. So right now I'm just looking at getting a better clutch and maybe doing a custom exhaust if I have the money left. Can I wait on parts like a programmable ecu, upgrading the fuel pump and injectors, and the blow off valve. Also I'd like to swap the head from my DOHC to the B6T to avoid having to get a hood scoop, has anyone does this(swapped heads)? Also is there any way to avoid having to use hood pins due to the intercooler? I would really like to keep this car as stock looking as possible. Thanks

[Josh]

definatly dont run it without the blow off valve. i thought i could get away with it. WRONG i blew the engine in no time. its true you dont need the 2nd gen MAF. you might be able to get away with not upgrading your fuel pump but you will have to at least upgrade your injectors, to the 1.8 miata, they are prety easy to find and cheep. i would swap the head anyways the ports are bigger on the B6BF, but i would try to swap the Cams over, isnt the Distributor on the back of the head on the B6T if so you would have to play with your pullys some to get the timming perfect, but im not sure why you would have trouble with hood clearance. with the 94- 95 ecu system its a pain to get a turbo setup to run properly a stand alone is the best, but i would personaly go with the Greddy E-manage if your going to go with a piggy back. and you shouldent need hood pins if you have an IC, you just need to modify the latch or find an IC that will fit better.

[jimgreenlee]

Thanks for your help. When you did the swap what all did you add or replace as far as parts immediately to get the car up and running?

[Josh]

actually i kept the B6BF block and its been built up with forged pistons and rods. the main difference between the two is the head and the pistons. the B6T is 7.9:1 and the B6BF is 9:1. but my new engine is 8:1. they are virtually identical motors. mazda used the same block on a number of cars. i changed the fuel pump, injectors, fuel pump regulator, put in a blow off valve and intercooler. and i used alot of stock hoses from a turbo probe for my piping. i made several trips to my local wrecker.
the only problem im having is with fuel management. its either too much or not enough. and the stock ECU trys to correct everything.
i hav the SAFC 2 but yet to get it working properly so im running without it for a while till i get some money to get it tuned professionaly.

[OsoSlo z28]

the blow-off valve is not a neccesity. some older factory cars didn't even come with them. it protects the turbo, NOT the motor. reason is, when you let off the gas the throttle plate closes, preventing any air from going into the motor. the turbo is still spinning and now the air has nowhere to go. so it starts to try to turn the turbo backwards(bad). i HIGHLY suggest using a bov or at least a bypass valve, though they are not NEEDED so to speak.