b3/B6 SOHC 8 Valve vs. 1.6 B6t exhaust port spacing question

[Aspire SVT]

anyone happen to know the difference in port spacing between a b3/b6 sohc vs. a b6t. I am curious if it were cost effective to purchase a b6t tubular mainfold for say a miata and cut off the head flange and weld on a b6 sohc8 valve flange. im guessing they will be slightly wider due to the larger pistons and cylinder spacing, the center ports (#'s 2&3 of my fms b6 sohc header measure about 2 1/4 inch from center of port to port. ports 1 to 2 measure about 3 1/2" center to center as well as ports 3 to 4. from ports 1 to 4 about 8 7/8". could prove helpful for someone looking to turbo a b3/b6 but wants a nicelly mostly fabbed manifold. i have had the b6 fms manifold on my b3 for about 4 years.

[thered56]

Heeey....I was just looking at that! I've been thinking about using the turbo from my B6T on one of my B3s. I kinda put my B6T exhaust manifold near the B3 in my car and it looks like a considerable difference. I'm gonna be bringing out one of my B3s today to check it out and start this planning process though. I'll give you some measurements in a few hours or so.

[thered56]

Okay, sorry bout bein later than I said I'd be. So, the ports are different shapes, the B3 being round, while the B6T ports are oblong. All measurements are approximate. The B3 ports are about 1 3/32" in diameter, while the B6T are 1 1/32" tall and 1 3/4" wide. Spacing between ports on the B3 is 2 5/16" between cylinders 1 and 2, and between 3 and 4, and 1 5/32" between 2 and 3. The B6T ports are all evenly spaced with 1 5/8" between each port. This gives an overall width (from the far side of each end exhaust port) of 11 1/8" on the B3, and 11 7/8" on the B6T.

All in all I can't see that working out, so I doubt those measurements were really necessary, but there they are anyways...heheh

[eurotiva]

Do this. It is alot easier than fitting it under the hood.

[Aspire SVT]

Didnt think it was possible but you never know for sure until its asked and then answered. thank you much for checking. im going to relocate the inlet for the water pump since my vehicle does not have air and utilize the stock manifold for placement of my vj14.

[sasquatch]

eurotiva, i love how your wastegate just dumps to the open air

[iceracerdude]

What does that thing sound like?

[sasquatch]

http://www.youtube.com/watch?v=BdY2_lmeTX0

i love the sound of it... that turbo sounds amazing and i love how you can see when the turbo kicks in and the rear just goes right done to the ground... that looks like one fun ride...

[bogeybob]

b3/b6

I just put a b6 into my 91 5spd festiva with ac. The post that the ports are different is correct. Round (b3) vs oblong (b6). I used the b3 intake and exhaust and original F/I rail. Intake water ports do not line up on intake side. Had to make an adapter plate of 3/8" aluminum. Am using b3 exhaust and ported it out somewhat. The exhaust two top outmost bolts do NOT match the b6 head. But port hole do match if ported out a little. Also if you put a b6 into the festiva and have AC you will have an issue with the pulley on the crank. The b3 is two pulleys and the b6 has a harmonic balancer and pulley combo that needs to be modified and used with a motified lower pulley from the b3. The center hole on the b3 crank is 1 1/4" while the hole on the b6 crank is 1 1/2". And the 4 bolts holding it on have a different bolt pattern. I did modify it to work. I cut the outer pulley off the b6 harmonic balancer and ground it smooth on front side, then used the outer pulley from the b3. The SPACE is then used between the modifed b3 outer pulley and the harmonic balancer from the b6, to place the ac belt. It lined up perfectly. Again, on the space between the harmonic balancer and the b3 outer (lower original modified) pulley..You will also find that the b3 valve cover is different than the b6 and has to be modified (hole drilling) to install throttle cable bracket.

Not sure if this is a good place to post this, but it was a project I wanted to try and leave some feed back.. It is running fine except for some hesitation in each gear. And is certainly faster. Next, looking foward to installing the b6 exhaust manifold when funds are available.

[thered56]

^^ Good to have some details about the differences. The comparison I made was between the SOHC B3 and DOHC B6T. I believe a different thread would have been better, but thanks for sharing.

[iceracerdude]

The amount of fabbing need to change a readymade b6t manifold to fit the b3 is so extensive, and would be so cobbled, you actually be better off just fabbing a clean log manifold from scratch.

[nonamekid]

I just put a b6 into my 91 5spd festiva with ac. The post that the ports are different is correct. Round (b3) vs oblong (b6). I used the b3 intake and exhaust and original F/I rail. Intake water ports do not line up on intake side. Had to make an adapter plate of 3/8" aluminum. Am using b3 exhaust and ported it out somewhat. The exhaust two top outmost bolts do NOT match the b6 head. But port hole do match if ported out a little. Also if you put a b6 into the festiva and have AC you will have an issue with the pulley on the crank. The b3 is two pulleys and the b6 has a harmonic balancer and pulley combo that needs to be modified and used with a motified lower pulley from the b3. The center hole on the b3 crank is 1 1/4" while the hole on the b6 crank is 1 1/2". And the 4 bolts holding it on have a different bolt pattern. I did modify it to work. I cut the outer pulley off the b6 harmonic balancer and ground it smooth on front side, then used the outer pulley from the b3. The SPACE is then used between the modifed b3 outer pulley and the harmonic balancer from the b6, to place the ac belt. It lined up perfectly. Again, on the space between the harmonic balancer and the b3 outer (lower original modified) pulley..You will also find that the b3 valve cover is different than the b6 and has to be modified (hole drilling) to install throttle cable bracket.

Not sure if this is a good place to post this, but it was a project I wanted to try and leave some feed back.. It is running fine except for some hesitation in each gear. And is certainly faster. Next, looking foward to installing the b6 exhaust manifold when funds are available.

What year is your B6 from? Is it the second generation B6 or the first?

[thered56]

The amount of fabbing need to change a readymade b6t manifold to fit the b3 is so extensive, and would be so cobbled, you actually be better off just fabbing a clean log manifold from scratch.

Agreed