B6 exhaust mani on b3

[funky technician]

Hay guys, I was just wondering if the B6 exhaust mani works well with the b3 motor, I know it fits, but does it improve the engine power or does it makes it worse (due to the larger primaries) Has anyone tried this? If it works well, i can change my entire exhaust over to the b6 mani and down pipe and a 2 inch exhaust (i have the complete system and can't mix and match because its all welded together and i'm not cutting it) I'm more or less looking at increasing the fuel milage to the max as my goal
Thanks

[91mcnasty]

Letting a motor breathe better is always a good idea, but I have no answers for you.

[Safety Guy]

I've thought of that, too. Just make sure you use the early B6 exhaust manifold on your B3. The 1990 to 1994 ones will not bolt up.

Karl

[M3NTAL]

Idk why someone would want to do this and have no REAL performance gain?

Seems like a WASTE of time for me, but that's my .02

Your probably going from 62 hp to 65 hp for all that work

[getnpsi]

You have to confirm first that the header side are the same port shape. if its a complete system I'd go for it. If you do a lot of city driving you may lose a little mpg from extra power being realized and less velocity. The trade would be a small at steady throttle. Breaking off studs and lining pipes up on your back takes just as long as swapping a whole engine by the way. I'm still on that step.

[blkfordsedan]

I've always wanted to do the same. The B6 manifold seems to have longer & better seperated primary passages as compared to the B3 unit. It should benefit from improved scavenging and reduced intake charge dilution. EFI engines are less prone to losing low-end due to larger primary tube size, as compared to carbed engines. I think it would be a great compromise between a full tube header & the factory manifold. I say go for it. It may not make a big difference, but I don't think you'll lose anything either. You can be the first and report the results.

[funky technician]

ya, i think i'm gonna try it out, I have the whole thing because i am scraping my b6 swap car because its getting too old, the body has 400 000 on it (the b6 in it had 360 000k, i rebuilt it, put 150 000 on it, and its still working perfectly, and doesn't burn a drop) I'm gonna take the engine out and strip the parts off the body i need (my new festiva needs stuff off that one that i just put on it new). I"m not swapping the engine into my new festiva though, not yet anyhow, I need to focus on milage for now with this car, i drive 2 hours a day to work. i found that my b6 car had TONS of power in comparison, but fell behind the b3 in the fuel milage. The biggest worry for me with this manifold is that the opening for the primaries isn't the same size as the b3 ports, so there gonna be a shoulder, which will cause turbulence, which is negating the scavenge you tring to gain, anyhow, its all hear say until i get it on and try, I'm gonna start this weekend and i'll keep yas posted

[blkfordsedan]

The ports in the manifold should be bigger than the ports on the head, correct? That shouldn't be a problem. In fact, having the manifold (or header) ports larger than the head can actually be beneficial. It creates a "anti-reversion" dam that will help keep the exhaust flow pulses in the manifold from backing up into the exhaust port. I wouldn't want it to be excessively larger, but I think it should be fine. In all honesty, I would probably swap the whole B6..........whats 4-5 MPG when you'll still get close to 40? You may end up losing a couple anyway swapping to the B6 manifold. No way to know for sure until you do it.

[Aspire SVT]

Done it, you will lose low end power and the fuel economy will suffer. Granted mine was on a b3 aspire with no cat and a 2.25 mandrel ss exhaust. It bogged until about 2700 rpm. Then the scavenging came back into play and it got better. Based on my experience I wouldn't do it. I got a jy mani and dp for the winter. All better

[blkfordsedan]

Done it, you will lose low end power and the fuel economy will suffer. Granted mine was on a b3 aspire with no cat and a 2.25 mandrel ss exhaust. It bogged until about 2700 rpm. Then the scavenging came back into play and it got better. Based on my experience I wouldn't do it. I got a jy mani and dp for the winter. All better

There you have it! At least that proves that it makes a difference over the stock B3 manifold. Sounds like It might be a viable option if combined with a ported head and cam upgrade on a B3.

Didn't you just sell a B6 header? Can you make a comparison between the two?

[funky technician]

Done it, you will lose low end power and the fuel economy will suffer. Granted mine was on a b3 aspire with no cat and a 2.25 mandrel ss exhaust. It bogged until about 2700 rpm. Then the scavenging came back into play and it got better. Based on my experience I wouldn't do it. I got a jy mani and dp for the winter. All better

Thanks dude, I was thinking that's what would happen, I'm just gonna get a high flow muffler, any sugjestions?

[blkfordsedan]

If you're after max MPG's I would stick with a quality factory replacement. Mine made the best MPG with full factory exhaust and there's plenty guys on here pulling 50+ MPG with stock exhaust.

[festyfreak39]

The bigger header would be bad for the B3, the ports are alot bigger, This means your exhaust fumes will loose velocity. Its kind of the same idea of putting an 4 inch exhaust on a festiva... it would have much less horsepower and tq then the stock size one.

If you want to gain power out of an exhaust system maybe increase tube diamter 1/4 of an inch and run it free flowing with just a muffler. no cats etc. And if you want to play around with the header match port the head with the manifold.

[ejp2fast]

My stock muffler rusted out and i just cut it off at the first bend at the front of the fuel tank.... and my mpg's suffer from it...