Port matching a PRC intake?

[mike.williams]

I know everyone fits an rbc intake manifold, but for that to work with my j's racing intake requires alot of work and money,

Im not really chasing power, i just want the car more driveable lower down so im getting it K100'd the end of the month, with this spec

Bc header
60mm maxracing exhaust
J's racing intake

Paul @tdi was very help yesterday and did suggest the rbc but run it with standard throttle body, this was £450 just for the parts then i would need custom intake hose/pipe to the TB making up.

So im wondering if anyone has ever bored out the stock PRC intake mani and fitted a bigger TB?

On the RHDjapan website for the spoon TB it says

The SPOON Venturi Big Throttle Body has a larger diameter than the OEM unit and will lead to an increased air flow which means an increase in horsepower. Because of the larger size, Spoon recommends the machining of your intake manifold to make the diameters even between the throttle body and intake manifold.

Anyone ever done this?

Cheers

 

[brucey87]

you may get a small gain, maybe 5bhp at the most. i have a 70mm Spoon venturi t/b mated up to my rbc. the t/b made hardly any difference especialy for the price of it!

 

[timp]

i ran a j's throttle body fitted to the standard mani and without digging out my dyno maps it gave about 3bhp peak but around 20 ib/ft bump in torque just after vtec cross over. The standard mani even if bored will not give you much the only way forward is the rbc with is what i did but bang for buck is not a great investment but does give you about another 10lb/ft in the mid

 

[mike.williams]

i ran a j's throttle body fitted to the standard mani and without digging out my dyno maps it gave about 3bhp peak but around 20 ib/ft bump in torque just after vtec cross over. The standard mani even if bored will not give you much the only way forward is the rbc with is what i did but bang for buck is not a great investment but does give you about another 10lb/ft in the mid

cheers for that, i may see if i can get a j's TB then but im not fussed like you said not much bang for buck, i can live with 10bhp less aswell, would rather put the money into my chassis

 

[C&S Evo7]

IMO you will get no real gain from a throttle body

 

[mike.williams]

IMO you will get no real gain from a throttle body

What about porting the PRC si?

Last friday Paul at tdinorth took me out in neils ep3. Stock motor with kpro and a 70mm TB and its making 215bhp. Felt good alot more responsive for stock

 

[leejw87]

I think the js and spoon are just oem units that have been taper bored to a bigger size.. Unless your going Turbocharged I don't think there's a real gain to be had from these..

 

[timp]

I think the js and spoon are just oem units that have been taper bored to a bigger size.. Unless your going Turbocharged I don't think there's a real gain to be had from these..

Would agree with that, probably most are can you image how much it would cost to design from scratch??

 

[barrettjona]

Sorry to sound like a noob, but why wont the rbc work with the j's racing intake?
Is not a case of connecting the two with a custom hose or something?
i know i'm no real help, just curious. :xconfused:

 

[mike.williams]

Sorry to sound like a noob, but why wont the rbc work with the j's racing intake?
Is not a case of connecting the two with a custom hose or something?
i know i'm no real help, just curious. :xconfused:

Yes you are right. But a bit more is involved. Check out blueguys build thread. He has done it

 

[dave c]

Unless your going Turbocharged I don't think there's a real gain to be had from these..

no point in it then, you get plenty of air through when its forced. I'd try and get the rbc on if you can. Great mod for gains

 

[paul hughes]

If you use a std intake manifold then boring it to 70mm is pointless as we had to cut it and weld in a bigger plenum chamber on the early Touring cars to even make a std TB work,, we then moved forward and used RBC when they came out, now we have moved forward again by testing and developing in Time Attack and use our CNC modified RBC which greatly improves flow if used with our true 70mm straight through TB, the best bhp we have seen on this set up is 305bhp NA and 220 Ft/Lb torque , so it will deffo flow enough for any road going NA DC5.
Call for more info, forum prices, and explanations 01772 299820.