Lol, we aren't talking about j-bridges here. And that is actually an even larger eye-brow than on the motor he was rebuilding when I went by.

 

+1

Except: What about ITBs? Would I need another set for the aux ports?, Could I do a cold air with ITBs?

 

With ITB's, you can get a 6-port manifold, so you just nee the regular ITB setup. They have that stuff at Tweakit, but it aint cheap. I have heard of people getting it to work with the stock LIM so they can keep the sleeves working, but I don't know details. For a cold air, you would have to custom fab something. I would think you could fab up a box to use the stock scoop on a tII hood.

 

Tweakit has a Turbo manifold for their ITB's that faces where the stock TII scoop would be. that could make a great setup for a cold air... And if you had the time and equipment would facilitate a hotwire MAF setup.....


BC

 

that would be pretty dope, especially since i happen to have an aluminum tii hood ^_^, i'm going to have to look into getting an ITB setup then and getting a aux bridged rebuild with 9.7:1 compression, boy that'd be a screamer even for N/A
hell might even throw in juice if i need it.

 

Fricken waste of time on a street car...

There are people on here who like to tout a lot of fantastic things, but none of the disadvantages.
The BP motor will not make better power at low RPM's.
The BP will consume more fuel (and not make more / better power) at low RPM's.
Now, unless your engine is going to live above 4kRPM for most of it's life while it's running, then those two disadvantages will affect you significantly.

If I were going to do a bridge port, I'd go all the way.
Full back cutting...cut the water jacket and shave the rotor housing itself...etc.
This is why I don't do it.
It's too much work for too little gain.
I'd rather go PP and go ***** out than go with a compromise solution like a BP.


-Ted

 

I just want the brap. Period.

Im well aware of all the power that can be made on a stock port, or light street port. Especially since Im talking about a turbo motor. Forced induction isn't going to care all too much about whether there's a eyebrow to pass through or not - its forced.....

But when I was having my motor rebuilt I didn't want to leave them alone - I want the car to sound like hell-on-wheels at idle. I don't give a fart about gas mileage - I DRIVE A ROTARY!! lol

thats my only reasoning - ego.

 

With true duals you want to have the least amount of overlap possible, so I would go for a collected system.

 

classicauto- Do you want to be my friend? j/k
I am with you on this one to a certain degree. I think of 350 with a big loped cam and wow! I love the way it sounds and if I suffer a little on the bottom end that would be a worthy price to pay to get what I want.

 

That basically it too - porting is messing with the duration, just like a cam.

And, yes, there are benefits to be sought from the porting - mostly with N/A's though. The only real "ceiling" you reach powerwise on stockports is north of 400 for S4's, north of 500 for S5's and 6's....so *really* unless you are making more power then that (or REAL close to it) Bridging is really essentially only for ego.

brap, brap, brap, brap.........

 

Full bridge, half bridge, doesn't matter. As long as neither cuts into the water jacket or seal paths then they are reliable. Most bridge failure comes from munched up side seals due to improper eyebrow cutting. Or the bridge cracks and fails because it's too thin. My bridge cuts a bit into the side seal path so it will be interesting to see if this has a major effect on engine life (I didn't want to cut the rotor housings so I could use them in a future engine if I wanted...).

Aux port bridges should not be considered. Either go half bridge or full bridge. I did the aux port bridge mainly as an experiment because I wanted to see if it would not produce the bridgeport idle but offer the advantages of a bridge at high RPM. Idle still braps and I have not taken the engine past 4K yet. It's certainly easy to drive at the low end and I don't notice any lack of torque as compared to a 6 port engine with the sleeves wired open.

 

Could you restate that, Aaron Cake? That last paragraph is confusing me. You tried aux portts as an experiment, haven't taken it past 4K yet, say its easy to drive at the low end with no noticable lack of torque. Yet you say they should not be considered, and one should go half or full. ???

 

Yeah, you can't really say not to do it if you've never even gotten to try them out.

 

If it still has the idle of a bp or hbp, yet you have not even taken it into the powerband then how can you say that you would not recommend doing it? There could be advantages that you have not discovered as of yet.

 

here's what bugs me, we build alot of track only cars.... meaning they literally NEVER see the street. so the wilder the better right? ehhhh... i have an example i'm going to explain and it's the main reason i shy away from bridges on a street car (even for highway use )

there are these two guys we deal with on a regular basis. they BOTH have two FD's. one for the track only and one for the street. they are always in competition with each other on the road course always coming back to us and saying "i want his turbo setup now, he is faster than me, etc....etc... )

well now they have pretty much identical setups except one major difference: one has a full bridge port and the other stock ports. the bridgeport car sounds amazing, the idle is scary and loud as ****. it's not brap, brap, brap, brap... more like BrrAAP..............................BRRAAApppp.... .................................................. ......brap........ you get my point. anywho, his **** does spool up pretty fast (not a huge turbo) , but it doesn't throw you in the seat. mainly because it has no guts until around 6000 rpms when it starts to pull really well all the way past 8k (he shifts at 9500 @ the track from what we can tell hahahaha).

the stock port guy, same turbo... this car spools up instantly and slams you in the seat and doesn't let up until you let off (right @ 7800 - 8k). they both make right about the same peak power but the bridgeported car just has a higher powerband and less torque. now i'm sure alot of you are thinking.. "ohhh it's in the tune, blah blah" no. our main goal is to keep these guys from blowing the engines at the track and they are making PLEEENTY of power. more than enough for the road course...

just take a guess at who usually wins hint: his car doesn't brap

 

If they are running the same turbo set-up then I see how this could be a disclaimer. If the guy with the bp chose a turbo more suited for his application then ther would be no challenge( this is based on all of my knowledge) A bp seems as though it would be more at home on a strip rather than a road course.(same as above)

 

well that was only one of many examples. my main point was not seeing the use of a bridgeport on a daily street car that wants power. yes that guys bridge would benefit from a bigger turbo but anymore than 500rwhp on a road course is asking for trouble. driver skill needs to go up if your still having a problem. the other guy realized he was wasting his time with the bridgeport when one of his competitors is out there making close to 600rwhp on stock ports

my theory is that all this power isn't really in the porting......... it's in the fuel but that is all in the alcohol injection thread and has nothing to do with this i guess.

 

That's kinda odd, it goes against everything I've seen and heard of. The more air you can efficiently move into the engine at low rpms, the faster you can spool a turbo. It has been my personal experience that cars that go from Sp to HBP spool faster with all else being equivalent.

 

That given example has too many variables to consider.
The BP is going to give you a more peaky / narrow power band.
So, if the ratios (i.e. transmission and rear end) are identical to the two cars, then it comes down to the track layout.
Some tracks are "slow"; some tracks are "fast".
This will dictate how well the ratios are matched to the track conditions.
It is conceivable that the track can be run with a peaky motor, but most of the time the revs drop low enough so that the SP motor will have the advantage.
BP + close-ratio trans will usually be superior...but how many of us can get a close-ratio transmission?
It doesn't surprise me that the SP motor would be superior.
The faster car is usually the one with the *fatter* power band - i.e. torque curve.

You can brag all you like about horsepower, but remember HP is dependent on RPM's also.
Jack the RPM's up and you will most likely gain HP.
BP's should be running higher-than-stock redlines.
No sense build a BP motor when you're "just" going to tach out to 7kRPM???
Most of the BP's run easily over that.


-Ted

 

ted, that is exactly my point! for a street car i see no good use to a hbp or even a bridge port. as far as spool i always find the best way to change spool characteristics is thru timing, fuel, and downpipes

my point of view is based on excessive overlap. my opinion is based soley on boosted rotaries, not n/a's where things completely change. the main thing you want is velocity. yes adding the eyebrow no doubt adds more flow, but is also adding overlap.

someone in here compared bridging to a hot cam in a v8. even the turbo v8 guys know that the best overall cam for a boosted v8 is either a stock or mild. nothing with alot of overlap. there comes a point where it's.... well.... pointless. if you want more power/ flow for a boosted engine then go wild on the exhaust ports and a large streetport and it's more than anyone will ever need on the street.

look at lupe and all those guys making in the 600rwhp realm. are they bridgeported? don't think so

again, i'm not trying to bash this. we build bridgeports often and they're bad *** for the track in a non-turbo car.

anywho, we are officially starting on the tune of my buddies car that actually has a BDC HBP in his TII using the MP Q-trim Big Shaft T70. going by what everyone in here thinks we should hit almost 500rwhp on pump gas/ 15 - 16psi. my personal thought? i think we'll see 400rwhp.. maybe a little more.

but if i'm wrong then HELL YES, like i told bdc i'm here to learn more as anyone in to these cars are. but when you're around 20 or more of these cars every single day you tend to see what works more than others.

 

Streetport here

 

I used the MP T70 when I had a HBP. I was having boost leaks but making around 395rwhp just under 1 bar. and then 480rwhp @ 19-20psi.

 

Good Lord, I don't even know where to start. With all due respect to the forum membership here... so many "experts" yet so few people here who have any actual, real experience with this.

I've got 3 1/2 years with turbo'd bridgeports under my belt and it was a path of experience that I was initially against. Needless to say, I was drastically wrong about my original preconceptions about it. The one thing I've learned philosophically about all of this is to never open your mouth about something that you know little to nothing of. That same philosophy applies here to this porting ideaology. It works, it works extremely well, with few downsides, but within certain parameters. The "problem" with it is there's so few people doing it, and even fewer "standards" out there that people will adhere to, for it to really be a competing point-of-view for the time being.

I'll write more on this later. I could write a book about this.

B

 

...and I (among others) would enjoy reading it.

 

+1