RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   New Member RX-7 Technical (https://www.rx7club.com/new-member-rx-7-technical-256/)
-   -   What is needed for a semi pp with street/half bridge port (https://www.rx7club.com/new-member-rx-7-technical-256/what-needed-semi-pp-street-half-bridge-port-1161366/)

spintowinrx7 04-05-23 08:16 PM

What is needed for a semi pp with street/half bridge port
 
Getting ready to send my 13b REW to chips motorsports for porting. I'm trying to decide if I want a full bridge (I'm aware of the loss of torque in the lower RPM range and how it affects drivability) or a semi PP with an aggressive street port or a semi PP with a half bridge. The build goals:

-450hp to 500hp goal
-Aggressive and or choppy idle
-street and weekend circuit tracks

I'm having trouble understanding what is required for a semi PP when it comes to the LIM and UIM. When searching older threads I saw people recommending RX parts 4 banger throttle kit. Is this 4 banger kit something that is 100% required to run for a semi PP? I currently just received my Xcessive manufacturing LIM, am I able to send that out for modification to work with the semi PP? I'm essentially trying to figure out what is needed for a semi PP such as LIM, UIM, and throttle body? can I just run the stock UIM?

Any info on this will be super helpful before I send the engine out. The older threads didn't go into specifics. Thank you!

BLUE TII 04-05-23 10:17 PM

What is required for bridge port or semi p-port to run is a lot different than what is optimal for them.

Most people run modified stock like intake components such as the Excessive LIM you mentioned because the turbo manifolds/downpipes available fit with them.

If you keep the stock upper intake double throttle there is some driveability tuning you can do on half bridge or semi p-ports, but the restriction and long runners are costing you power.

There are downsides in both power and driveability with the stock based designs.

Companies like Projay that specialize in semi p-port engines have evolved entirely different intake manifold designs for higher performance.

Though because Projay is drag oriented there is likely little concern for driveability in some of their designs. Some time attack cars use Typhoon intake however.

Originally there was the "carb style" 4150 manifolds and their short individual runners.
These work well for driveability on half bridge/semi p-port with staged TB and work well unstaged with full bridge as it eliminates intake runner "communication".
Some downsides are they take up a lot of turbo/downpipe space and the FD doesnt have a ton of room in this area. Early designs had sealing issues between engine and manifold as well as TB and boost hat (single bolt). You usuallly end up with injectors over your hot turbo/downpipe.

Then Projay diverted from modified 4 barrel styles and offered the "typhoon" which is designed ground up semi p-port specific with a large single throttlebody.

Next they continued to clear turbo/downpipe space with the billet series that is in the cnc machined and bolted together style. Looks like a robot member...

Since your power goals dont align with the porting options you want (stock or street port would be fine) I assume you want the big ports for the experience of all the ports downsides (kinda like riding a Harley).

The easiest path will to be a bridge and unmodified intake and turbo kit components. That way everything just bolts up more or less.




spintowinrx7 04-05-23 10:39 PM

Thanks for the response! This cleared a lot of the confusion I had about LIM, UIM, and TB. I think I’ll just do an aggressive street port


All times are GMT -5. The time now is 06:41 PM.


© 2024 MH Sub I, LLC dba Internet Brands