how much longer would a port job like that last for? im sure with finishing and a lot of polishing it would be better... u had no problems with this port?

 

bridgeported motor on thepartstrader.com 240 horses

 

Well cracking of the bridge is only one of the problems with the bridgeport and having a meaty one like this would most likely prevent that. The problem i had with this motor was the ceramic apex seals. They last forever but tend to be a little more brittle than the steel ones. In my case i revved mine a little hard (about 10-11,000rpm another no-no with ceramics) and lunched a seal. The second time, I was told that the apex seals wouldn't need clearancing, so i put them in and they expanded, jammed and cracked. You live and learn, but i don't think i'll use them again.

 

how many rpms can the ceramic apex handle?

 

Well i think they were originally made to use in turbo motors because they have good sealing properties at lower RPM's, but they are quite heavy compared to steel or carbon seals. A lightweight seal is better for a high revving engine if you want it to hold together, I've heard.

 

The main problem with the bridge is the overlap, this tends to cause poor MPG on the bridge but the sheer size of the port gives it alot more mid and top end power (over an Extended port).

I have heard about people running very big extended ports with massive exhaust ports giving it lots of overlap.

As i say the only thing i dont like about the bridge is the MPG but this is quickly forgiven when u hit the gas.

 

Heres my .02...

This is why I fell the way I do about a Bridge port...a guy I know that used to work for Tri-point put a N/a 13b (s-5, carbed) in a little mazda truck, it had a very nice bridge port, and all the extra goodies. He drove it for over 50k! and stomped on all the rice he wanted to. The idle was nice, and the MPG was decent.
the powerband was good for around town, but once the tach hit 3,600 or so it reallt put you in your seat!

So, why not? If you can do it for a good price,( or if you can afford whatever you want) I say go for it!

 

I would like to see some people with N/A secondary bridges.
Either most are unclear about it, or they have full bridgeports.
A dyno of a N/A street (maybe even daily) driven secondary would be nice

 

I think I might have a copy of one around here somewhere, just have to look............
Not sure if it's one of a full bridge or not?
but it was a daily driver N/A

 

my engine is being ported right now

extened port on the priamary
bport on the secondary

 

lemme throw my opinion in here. i have seen todd's rx3 both being driven on the street (its quiet) and on the dyno to 9500+rpm, and that car is streetable. my definition of streetable, is the list of things you tell someone when you give them the keys.
if they have to do a bunch of stuff to drive the car (pull the choke, pump the gas, flip swtches, keep it over 2500rpm etc) its not streetable. theres also a huge difference between a race car that is street legal and a fast street car, and it all boils down to personal preference

mike

 

What like dont hammer it till its warm and let it cool down before u turn it off?

Does'nt that go for all Turbos?

 

His car sounds fantastic. I know someone (was it RETed?) said that he had a few secrets in the car

 

i would like to see more about this

 

All right I think it is time I put my 2 cents in here. My motor put out 220 at the wheel with 135 Ib running dual mufflers street exhaust and Holley 700 CFM. It peaked at 9,300 rpm. The porting was actaully not that aggrasive. I had the bridge port on the top portion so it actually has less over lap and later open timing compare to ones that are cut all the way down along the side of the main port. It closed relitively early, pretty close to stock turbo timing. The result is GREAT response and 22 mpg on high way below 75 mph. I had cheese port, bridge secondary, bridged primary and secondary, bridge to water O ring, bridge pass the water O ring. In my opinion if you are going to bridge go for J bridge. A secodary bridge or a small bridge will have the charicteristic of a big bridge but with out the top end power, how ever it still idles lumpy and has the same overlap to require free flow and some times loud exhaust. I have personally never encountered bridge cracking and my bridge is 4mm thin ( the key is to keep the bridge SHORT, it goes perfectly alone with the timing I like as well how ever on a J bridge it will start to drink water after about two year or 20 k street miles, it will not over heat or loose water as you drive, just foul plugs when shut off over night and may be use about a quart of water every 500 mi. I don not see the need for ceramic seal because I think 2mm 3 piece or 2 piece iron seals are just fine. Carbon seal will work but it just does not seal well with out the end piece so a lot of low end will be lost. ( remember the 787 actaully had 2mm 2 piece iron seal.) The motor will run and last a while but it will start to loose power after I would say 25k- 30k. I had one J bridge with approx. 28k of street miles and about a year worth of monthly track event miles. At 28k it looked like a stock motor with over 100k. It still ran good but just not as fresh as new and smoked under vacum. I think with Webber and open exhaust my RX3 would have made may be 15-20 more HP at the wheel, but that means 10-12 mpg and ear plugs too. People will tell you they tech their bridge port or PP to like 11,000 or 13,000 rpm well I am sure it can rev there ( mine went to 11,200rpm) but I can garrantee that is not where it peaks. Reving it that high is just beating on the motor. RX3 had BONE STOCK motor internals except oil pressure regulator and STOCK 85 ignition. OH The time I spend on the carb, was more the 3X the time on the motor.