Bridge Port Or Not ?
07-16-02, 06:22 AM
#26
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Originally posted by HWO
reTed will tell you not to bridge port, cause ya know if you had a bridgey and he had his car and you were only racing to 4000rpm he'd walk all over you............
reTed will tell you not to bridge port, cause ya know if you had a bridgey and he had his car and you were only racing to 4000rpm he'd walk all over you............
07-16-02, 06:30 AM
#27
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Quote,
(Don't even worry about the power production... max HP has nothing to do with low load low RPM operation. Just think about how a bridge/peripheral port engine idles, i is constantly stumbling over itself with any appreciable manifold vacuum because the overlap period allows the manifold vacuum to draw exhaust gasses up into the next chamber causing the cyclical misfiring that makes rotorheads smile but hurts economy.)
Is this what is caused by over lap?
(Don't even worry about the power production... max HP has nothing to do with low load low RPM operation. Just think about how a bridge/peripheral port engine idles, i is constantly stumbling over itself with any appreciable manifold vacuum because the overlap period allows the manifold vacuum to draw exhaust gasses up into the next chamber causing the cyclical misfiring that makes rotorheads smile but hurts economy.)
Is this what is caused by over lap?
07-16-02, 06:32 AM
#28
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What good would it do? The issue is fundamental... the manifold vacuum is lower pressure than the exhaust gases, and the exhaust gets drawn up into the next chamber. Eventually it starts misfiring and exhaust gas pressure drops to the point where this "built in EGR" diminishes to the point that there's minimal dilution and it starts firing again... in other words "brap brap brap".
Even stock ports will do this at high enough manifold vacuum, it's why a pre'81 carby engine will buck when coasting down in-gear.
Even stock ports will do this at high enough manifold vacuum, it's why a pre'81 carby engine will buck when coasting down in-gear.
07-16-02, 09:25 PM
#33
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Originally posted by Grizzly
when u say the fuel economy will be excsive on the Bridge is that comparing the two types of porting at the same Bhp? ie for example two cars with the same set up (turbo,fuel etc) one has a big extended port and the other has a Half bridge runing diffrent boost to keep the BHP the same (roughly) will the fuel consumption be simalar? as the street will need to run more psi but there wont be much in the cfm of Air fuel being put in the compresion chamber?
What i am trying to say is the Extended port better on fuel due to the less bhp its running? i under stand that the whole set up of the two engines (Ecu) will be diffrent but in theory is this how it works?
when u say the fuel economy will be excsive on the Bridge is that comparing the two types of porting at the same Bhp? ie for example two cars with the same set up (turbo,fuel etc) one has a big extended port and the other has a Half bridge runing diffrent boost to keep the BHP the same (roughly) will the fuel consumption be simalar? as the street will need to run more psi but there wont be much in the cfm of Air fuel being put in the compresion chamber?
What i am trying to say is the Extended port better on fuel due to the less bhp its running? i under stand that the whole set up of the two engines (Ecu) will be diffrent but in theory is this how it works?
) in.I haven't seen many people talk about their MPG with their high HP rotaries (i don't blame them
), but i assume a partial bridge would be somewhere inbetween a large streetport and a full bridge for fuel consumption ?
07-16-02, 11:19 PM
#34
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O.K. I've decided to bite the bullet and go with a partial bridge ,question is should I stick with the 1.15 A/R turbine or swap it out for a 1.32 a/r (or 1.22) housing? .
07-18-02, 02:07 AM
#35
ya do the b port, but watch the gas, thats the only thing that i dont like,, but if you want power all the way to 9 or 10 rpms then do it, i love my b port , i drive my car 20 miles a day.. i made 336 at wheels with 10 psi with stock mass air flow sencer and stock intercooler, and 60-1 with a .84 a/r.
07-18-02, 02:39 AM
#36
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I'm not sure of the best turbine trim for a partial bridge. Maybe talk to soul assassin, he recently changed from a partial bridge set up making 620 rwhp to a full bridge engine. He will be able to give you some good advice. So would crispeed. He runs a partial bridge and low 9 second 1/4 miles. Both top guns here on the forum
www.hitman.hm has some turbo info if i remember correctly.
www.hitman.hm has some turbo info if i remember correctly.
07-19-02, 01:59 PM
#38
why would you run such a small (.84) exhaust housing with a 60-1 compressor? Especially with a bridge ported engine, that doesnt seem to make sense to me. It's like strangling the motor. I'm running a 1.15 div/tang p trim back housing on my t04s which has a 60mm compressor. it spools fast (3000-3500) and lets the engine flow nicely up the rpm range. With bigger porting like a bridge, id say go even bigger, 1.32 would probably be the best bet.
anyway, for marcell with the 70mm wheel, id probably think 1.15 would be a good idea if you want to drive it on the street. You could always switch it out if it isnt large enough anyway..
also your fuel isnt NEARLY enough
get some 1600s up top, and at least 850 primaries.. maybe 1200s, and some extra injectors if needed.
as for reliability, youre cutting through the water housing o ring, and blocking off part of it... you will decrease longevity of the motor..
im sure all this has been said already somewhere else or even here but im too lazy to link/read..
peace
anyway, for marcell with the 70mm wheel, id probably think 1.15 would be a good idea if you want to drive it on the street. You could always switch it out if it isnt large enough anyway..
also your fuel isnt NEARLY enough
get some 1600s up top, and at least 850 primaries.. maybe 1200s, and some extra injectors if needed.
as for reliability, youre cutting through the water housing o ring, and blocking off part of it... you will decrease longevity of the motor..
im sure all this has been said already somewhere else or even here but im too lazy to link/read..
peace
07-19-02, 03:37 PM
#39
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I am not compromizing the water seals in any way ,I plan to leave 1-2 mm of metal to ensure this , as for the fuel aspect I am going to weld a stock primary injector fuel rail into the top manifold ( like on srx7 site) and install two 850cc injectors which are to be run in parallel with the 1300' s ( cheaper than byuing new 1600's!) , so this would be a total of four 850's and two 1300's, more than enough gas .
07-19-02, 09:27 PM
#40
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Marcell, you're gonna have a great car. The 66 and the BP, IMHO, are a killer street setup. It'll make great HP at low boost levels all day long, and when its' time to turn up the boost... Look out
All best,
Steve C.
All best,
Steve C.
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