karism

This is the engine setup that i will be running soon.

Hopefully the bridge wont crack this time,i will be breaking in for 200 miles(if i can manage not to race it).
2.25 " header ,with 2.5 " exhaust, i silincer.

Modified nikki,Nippon Denso Fuel pump (Jaguar)

Note that this is not my actual housings,seeing that my engine is closed and ready to be fitted.

Opinions please !

zyounker

dbl post.

zyounker

Cool... not so sure about your carb choice though..


And whats with the drill holes rather then just an open whole???? I have seen this before, but was told by the guy that it didn't help with power. but gave him the bridge sound.. but his wasn't a j-bridge..



-Zach

WackyRotary

I doubt those holes will yield very good flow through them at upper rpm. Please explain why they are like that?

DriveFast7

iTrader: (1)

It's not a J-bridge but a "cheeseport". Holes are drilled thru plate like swiss cheese. Holes are typically larger at the combustion chamber side and smaller at the intake runner side. Creates a choke type of effect increasing velocity. I've ridden in a car with one before. Sounded just like a bridgeport and made OK power. Better than a streetport. Builder said a Rx4 cheeseport motor with trick 12a Nikki carb put out 215hp at the flywheel but the owner said it felt like less.

WackyRotary

"cheezeport"! LOL!!!! I can't believe there is a REAL term for that. And I don't mean any disrespect, but I would never cut my bridges like that in the name of having a bridgeport sound, and only marginally better power then a streetport. My bridge is a full bridgeport with the water seals intact, and relieved rotor housings. My motto on this issue is, if you going bridgeport, go all out or not at all.

Fennix_sr

but hey, i bet it would sound prety cool while making more power than a streetport, id do this possibly, but what about longevity?

RotaryMotorDisorter

thats kick ***

DriveFast7

iTrader: (1)

Killing some time on my lunch break.....Here's some more bridgeport food for thought.

Eyebrowport:
One extra port cut into each side of the plates (not a series of holes like the cheeseport)

Not a full length port. Does not run the entire length behind the main port. It is a half length port and it is cut into the upper part. Using karism's pictures from above, you would cut a port into the upper four cheese holes of his cheeseport. Like connecting the dots of the upper four holes, both rows, and grinding all that out. And streetport the main port of course!

Idea is to still add highrpm power, but reduce port overlap. There will be less communication between the exhaust port and the eyebrow port since the eyebrow is further away from the exhaust port.

:0

81Rex6port13b

any one ever thouhgt of doing like a bridge port but only half way then the cheeze style the other half?

1st7heaven

That looks like the beginings of the bridge. You cut a series of holes and then grind it out. Why wouldnt you just finish it?? I wouldnt think that the air flowing through all of those holes would be consistant??? I dont know!!!????

Rotary7s

I asked about this style port job way back ..Noone knew much abotu ti ..I know a guy who has it on his car..

I cant say its a good style port..

Why dont you run some dynos after its done..
ANikki carb seems like garbage for anything bigger than a street port.

I hope you didnt bead blast yoru plate faces,
On that style port..some one said it would cause turbulance...What exhast porting did you do?

Rotary7s

Heres a bridge



Heres a J bridge

REVHED

Complete waste of time IMHO because having a lot of overlap is of no use if the ports won't flow. About the only thing you'll get is the sound. Actually, if anything they'll probably hurt performance as you still get the drawbacks of large overlap at low rpm without the high rpm gains.

1984special

LOL I lauged for a while when I read cheeseport and saw those funky holes. You say it doesn't do anything? Well I wouldn't be suprised because i've never heard of this port... while bp and pp and sp are pretty commonly thrown around this forum...

Well I'd love to hear more about the cheeseport...

Later

mperformance

I had never seen that before...

karism

The main reason i did this,was for durability.
I have done quit a few bridge ports,and they just dont last,especially j-bridge engines.

Thanks for the opinions,much appreciated.

I`am using the carb for breaking in purposes,seeing that i will never be able to supply enough for the setup.

Previous results with a single row of holes was good,real good.Some of you might laugh at the hp figure i`an shooting for,but remember i`am more than 5500 feet above sea level.

The flow of the holes will be less than a bridge,thats for sure.I like to experiment,and this engine is one of them.

For interests sake : The previous setup (single row)
Would happily rev to 9500 with a 48 IDA,making very top end,and not dropping off.

karism

Where`s Scalliwag ?

Ok..let me give more background :

Balanced,clearanced rotating parts.
60 Deg streetport.
6mm (0.23 " hole size)
120 psi oil pressure regulator.
Ported oil passages.

The rotor housings are off a Flat-track j-bridge.Epoxied(yes...i cant spell that)
Exhaust ports are large,square on the inside....2 " on the outside.

I will be fitting EFI as soos as the break in time is over.

Sorry that i cant post pics...no digi cam. I will however try to get pics of items similar to mine

REVHED

Interesting to know what sort of power that will make.

BTW, I've never heard of cracking bridges being a big issue with n/a bridge-ports. Maybe you were making the bridge too thin?

karism

I do make the bridge thin,i agree with that,but not as thin as the bridge pic that Rotary7s posted (j-bridge).

The previous ones did rev high,with the right carb/or efi combination it did do a constant 9500+rpm.Temps were normal usually,never overheating.

I`am not sure why the bridges were cracking,no 2 engines ever broke the bridges at the same place.

I`ll do a dyno run when all is completed,but that will be more than a month from now.

Scalliwag

I like the idea of the "cheeseport" and that sounds like a pretty well fitting name. But here is the question/concern I have. Of course I would not expect to see the flow of a bridge even in the best case scenario with this. No way in hell is it going to come close to a J port.
From a picture all you can see is a bunch of holes so this is the question; are the holes just drilled straight through and left alone or are they "flowed" afterward?
I can see that if let's say you used a 1/4" drill bit and made a hole and just punched them through at 90 degrees from the side seal surface. If you took a 1/8" straight rotary file and bevelled the backside of the hole in the direction of the port inlet it would greatly improve the flow. Think of what I am trying to explain as a sort of countersunk hole from the inside of the port. I hope this makes sense?
This would really do well with a forced induction under boost I would expect. But it looks like a good trade off in the strength vs. HP for someone that wants to drive the hell out of their street car day in and day out
Did you do anything to the backside of the holes?

Aico

What kind of mileage do you get? If it's like a SP then it might be interesting

DriveFast7

iTrader: (1)

The 79 rx7 i rode in with a rx4 13b motor with the cheeseport did have champfered holes. the holes were larger on the rotor side and were smaller on the intake runner side. created a choke effect like in a carburetor, increasing velocity. It was a road race track only car and scooted along quite well. Owner's in Northern California, I still have his email address.............hmmmmm......... might drop him a note.

His goal was not to jjust get the brapp-brapp of the bridgeport. He wanted more power thana streetport but didn't want to loose all low end torque like with a full J-Bridge. This car was run in the NASA enduro series too!

Scalliwag

I would like to see the chamfer on the other side. You could use larger holes to create more flow. I think there would still be plenty of low end with that setup plus extra for the highend. Of course depending on the type of driving you like to do. I like straight and fast

Jeff20B

iTrader: (13)

This cheeseport idea is pretty cool. I've got an engine to try it on. I'll think about it.