DOHC B6 Information

[F3BZ]

interesting. thanks for your input. the 100% was a "hypothetical" limit but mathematically impossible. just wondered how close to that would be ideal. my build goal will require the engine be moved forward as much as practical and my old school magazine thinking was that it would hurt handling so this is good news. now it brings up other questions. i wonder how much this affects the contribution of the rear brakes if the rear of the car is unloaded by the fulcrum?, effect of a heavy front end. do you use an adjustable proportioning valve? or as silly as it seems, if they don't contribute much, could the rear brakes and their unsprung weight be removed? not on a street legal car of course.

[Advancedynamix]

only if you promise to keep your hood closed. otherwise nobody will even notice the X.
this is more of a suspension question but since it comes up in this thread i'll ask. in the world of exotics, it seems that a mid engined car with 50/50 (or 25/25/25/25) weight distribution is pinnacle. maybe that applies to RWD or AWD. in your opinion, if you could hypothetically have up to 100% of the vehicles weight on or beyond the front wheels of our cars, what do you think would be near an optimal and safe weight distribution for a road course driven festiva?

We are working on that. 100 percent isn't ideal unless you have a gyro stability management like a segway vehicle, but as much weight on the front wheels as possible is optimal on a FWD vehicle.
The rear wheels do very little on a FWD vehicle and weight over them actually acts to spin the car in circles under hard cornering. Weight forward of the front axle stabilizes the chassis and helps with driving and cornering grip ( but ultimately, any weight is counter productive, so try to keep things light).
RWD platforms do work better with weight on the rear wheels, but any more than 50% will make the car hard to drive at 10/10 of the limit. Ask any Porsche race driver.
AWD cars also benefit from weight forward designs. Both Subaru and Audi have had great success with front weight biased AWD cars.

After a few years of testing, and playing around with these light FWD cars, I'm convinced that the old 50/50 mid rear platform is inferior in many ways to a lightweight fwd car. In street trim, my B6t Festiva would out corner even the mighty Lotus Exige with it's ideal chassis configuration. I watched one slide off the track in my rear view mirror as the driver attempted to follow me into the carousel at firebird Main coarse. Apparently the Festiva can carry more speed into corners than the Lotus, even with less tire under the car. The two cars were nearly identical weight and HP, but the Lotus was no match for the Festiva.

[bhazard]

100% of the weight on the front....so the rear suspended by helium balloons???

[F3BZ]

only if you promise to keep your hood closed. otherwise nobody will even notice the X.
this is more of a suspension question but since it comes up in this thread i'll ask. in the world of exotics, it seems that a mid engined car with 50/50 (or 25/25/25/25) weight distribution is pinnacle. maybe that applies to RWD or AWD. in your opinion, if you could hypothetically have up to 100% of the vehicles weight on or beyond the front wheels of our cars, what do you think would be near an optimal and safe weight distribution for a road course driven festiva?

[Advancedynamix]

wow! those aren't just motors. that's detailing taken to the level of art. goes to show you don't need B.S. chrome to dazzle. i'd put clear plexiglass hoods on these cars

With any luck these cars will both be at Madness this year, so swing on down with the GTX.

[F3BZ]

wow! those aren't just motors. that's detailing taken to the level of art. goes to show you don't need B.S. chrome to dazzle. i'd put clear plexiglass hoods on these cars

[Advancedynamix]

Here are some photos of a B6D mounted in a WA Festiva. This engine is 3/8" lower than stock, but in the stock fore/aft location.




This setup uses the Capri inlet pipe and airbox with a 323 flex hose and a custom spacer ( the Capri flex hose would work better, but isn't available new as far as I know)
The Festiva air box and inlet pipe can be used on the b6d Capri intake manifold/throttle body with some hose re routing.

Here is a b6t mounted forward in a WA Festiva with a G15mr (Caprixr2) transaxle and axles.

[Advancedynamix]

The engine weight moving forward is only half the benefit. A rearward angle on CV shafts also helps to improve traction on a trailing link suspensended drive system.
Also, moving weight will always be more beneficial than adding weight. Keeping the car light is important.
If you use a g series transmission (which is almost a necessity with more than 150ft.lbs of TQ) you'll have to move the engine forward anyway, because the centerline pitch of the input and output of the g transaxle is longer. Also, the transaxle hits the steering rack on the left hand drive cars when you try to mount a g series in the stock location. Either way, moving the engine forward is more important than the Turbo manifold being used. Even a poorly made basic log will provide wheelspinning bababababoooooost! :p

[bhearts]

The DOHC head isn't any wider than a B3 head where the ports are, it's only wider above the ports, but there is actually more space because the ignition wires don't go there. The top mounted turbo would work better with an e series tranny and a stock mounting location for the engine, but what's the point in all that turbo TQ with the engine in the stock location? These cars hook up much much better with the engine moved forward. This isn't a small change, it's an enormous difference. So much so, that Nastiva ( the guy who bought Tweak) prefers to drive his 180ftlb b6t car in the rain over his 60ftlb b3 Festiva. Both cars have the same tires, and suspension( with appropriate spring rates for the different vehicle weights/setups.) The engine forward b6t hooks up better and is more stable and comfortable to drive than the stock setup. Adding lots of TQ to these cars without moving the engine weight forward is like having a slip n' slide on a sweet hill out back and not turning the hose on.

What's an engine weigh? 230? If not at all possible to move engine forward, moving radiator forward, adding a fmic could offset that weight lost from not moving the engine forward. 230lbs 2 inches, or 35 8 inches forward makes a pretty big deal

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[Advancedynamix]

The DOHC head isn't any wider than a B3 head where the ports are, it's only wider above the ports, but there is actually more space because the ignition wires don't go there. The top mounted turbo would work better with an e series tranny and a stock mounting location for the engine, but what's the point in all that turbo TQ with the engine in the stock location? These cars hook up much much better with the engine moved forward. This isn't a small change, it's an enormous difference. So much so, that Nastiva ( the guy who bought Tweak) prefers to drive his 180ftlb b6t car in the rain over his 60ftlb b3 Festiva. Both cars have the same tires, and suspension( with appropriate spring rates for the different vehicle weights/setups.) The engine forward b6t hooks up better and is more stable and comfortable to drive than the stock setup. Adding lots of TQ to these cars without moving the engine weight forward is like having a slip n' slide on a sweet hill out back and not turning the hose on.

[sketchman]

Mine in the ME will be top mounted. Not log though, tube manifold. It's almost together. Another day and it'll be done. It's gonna be tight. Wouldn't want a wide DOHC head to make it worse.

[Advancedynamix]

http://www.ebay.com/itm/1989-1993-MA...CModel%3AMiata

this looks pretty nice. i wonder if one could fit a turbo on top in a festiva like they do in a miata.

It may work, but would require some creativity for sure. Possibly a Kia g series trans to tip the engine? It definitely would require some custom upper radiator support mods, especially if your engine is mounted forward.

Here you can picture the amount of room you'd have for that top mount setup.

[Advancedynamix]

I see that the festiva is the wa model. Do you know whether the DOHC motor will fit the WB 95-97 model.

It should fit better. I don't know for sure about hood clearance, but I do know everything will bolt up, or there are Mazda parts at the salvage yard that will make it bolt up. The engine mount is the only tricky part.

[jhntu]

With the right custom exhaust, anything is possible.

[bhearts]

http://www.ebay.com/itm/1989-1993-MAZDA-MIATA-EUNOS-ROADSTER-1-6L-B6-CAST-IRON-TURBO-MANIFOLD-/121637561740?fits=Make%3AMazda%7CModel%3AMiata

this looks pretty nice. i wonder if one could fit a turbo on top in a festiva like they do in a miata.