Rb30e Exhaust Size 2.25 Inch Too Small?

[rorz]

Hey guys, i did an engine conversion from a RB20DE redtop to a RB30E. I used the original 20de exhaust which is 2.25 inch in the middle, is this too small for the RB30E???

Also, the spark plugs are a bit black? i dont see how it could be running rich its feul injected. The AFM is reading 382 ohms which is good apparantly.

And it seems to loose power around the 3.5rpm + stage. No idea why but it just feels like its really holding back. Could this just be becuase of the exhaust??

Cheers

[ignuz]

Hey guys, i did an engine conversion from a RB20DE redtop to a RB30E. I used the original 20de exhaust which is 2.25 inch in the middle, is this too small for the RB30E???

Also, the spark plugs are a bit black? i dont see how it could be running rich its feul injected. The AFM is reading 382 ohms which is good apparantly.

And it seems to loose power around the 3.5rpm + stage. No idea why but it just feels like its really holding back. Could this just be becuase of the exhaust??

Cheers

I wouldn't base your problem entirely on the exhaust.. but perhaps upgrading to 2.5 would show some better results.. as 2.25 is a little restrictive for 3 litres..

[rorz]

OK that's what i thought. Also, im using the black thing (black cylinder about 15cm long and 7cm wide?) that seems to have 2 air hoses connecting to the top of it and a fuel hose at the bottom ( i have no idea what this thing is) from the Rb20, does this matter? it looked exactly the same as the RB30 one.

Edited November 7, 2006 by rorz

[racsov500]

2.25' is bigger than factory, but ideally you want 2.5"

are you talking aboutt he charcoal canister?

is this an R32? rb30 r32 eh...

[rorz]

2.25' is bigger than factory, but ideally you want 2.5"

are you talking aboutt he charcoal canister?

is this an R32? rb30 r32 eh...

Nah this 2.25 is the factory exhaust off the RB20DE! And im pretty sure the rb30 uses 2.5inch factory thuogh im not sure. Yeah i think its the charcoal canister i actually have no idea what they do but is it ok if im using the RB20de one on the Rb30 engine?

And nah bro it's an R31 ,some R31's came out with RB20DE red tops (with the crappy NICS system)

Edited November 7, 2006 by rorz

[_Scotty_]

The factory R31 exhaust is tiny, most people that upgrade their exhausts go for 2.25" or 2.5"

[342Four]

stock rb30e zorst is etiher 1 3/4 inch or 2 inch - far too small for the rb30 - 2 1/4 inch mandrel bent or 2 1/2 press bent is good

[rorz]

really? That's very very weird becuase i measured the diameter of my STOCK rb20DE and Rb30 exhaust in the middle of the system (under the car) and it was 2.25 inches. And thats stock as a rock.

[_Scotty_]

Well, this is the section of an Aus R31 exhaust from the cat to just after the diff. Hopefully the picture will give a decent idea of the diameter (compare it against the exhaust hanger). It's definately smaller then 2.25".

[rorz]

Hmm maybe it isnt 2.25 im sure the vernier caliper i used read 2.25 though. Anyway, does anyone have any idea about it running rich? the spark plugs are black, and at idle the exhaust has an irregular little 'pop' noise. And then as soon as i get in the high revs it feels like its running lean becuase of the loss in power?

[SKiT_R31]

Hmm maybe it isnt 2.25 im sure the vernier caliper i used read 2.25 though. Anyway, does anyone have any idea about it running rich? the spark plugs are black, and at idle the exhaust has an irregular little 'pop' noise. And then as soon as i get in the high revs it feels like its running lean becuase of the loss in power?

Mate you shouldnt lose power from running lean, infact the opposite should occur.

Stock pintara (CA20e) exausts are 1. 3/4" in diameter and stock R31 Skyline exhausts (RB30e) are 2" in diameter.

2.1/4" should be ok for an rb30, though you could lose a touch of power in the high revs, which doesnt matter too much as rb30's arent really made to rev. Once you start modding it though i would opt for a 2.5".

Also if you'r running the stock exaust off a RB20DE you'll probably find the muffelrs in it wouldnt flow too well etc, your best getting a 2.5" system, with a brand spanking new muffler (go offset) and resinator.

As for you problems, if its popping at idle, i'd check your TPS, could also be your air regulator etc, check your 02 sensor (maybe just give it a clean) and check your water temp sensor (clean it with a scourer until its shiny copper).

When you rev it, like stomp it and keep it revving high, does it blow black smoke? And when you say its losing power, can you feel or hear it missing?

Check for leaky fuel injectors, clean (with contact cleaner, and by scraping, also by bending pins so they sit tight) all your connectors, so that for each injector, the afm especially, 02 sensor, water temp sensor, tps, air regulator, CAS, etc.

Check yourdizzy and rotor button, scrape off all the white powder build up, and blow it out of the cap, check the resistance on all the leads, clean and gap the plugs...

after doing all this, your car should feel heaps smoother and should feel like its got a fair bit mroe power.

Also check the timing, and maybe advance it to ~ 18-20degrees (depending on what fuel you want to feed it)

[aDrew_C]

Just to clear up some confusion here,

You obviously have a HR31 (import), everyone here however is talking about R31's (Local). R31's have a stock 2" exhaust, and HR31's have a 2.25 (like yours). A 2.25" exhaust is fine for an RB30e and a lot of people prefer them because of the sound (less drone). However being a factory exhaust your 2.25 probably wouldn't match up to a 2.25 mandrel bent with just a cat and a muffler/cannon for example. So it could still be causing a bit of restriction.

[rorz]

Thanks for the suggestions SKiT_R31 i'll look into that

And yeah sorry i maybe didnt make it clear the exhaust im talking about is the Rb20DE from a GT Passage (jap spec).

The power loss doesnt seem to have a miss associated, the car just pulls up to about 3 - 3.5rpm then after that it just stops pulling and makes a nice exhaust/air noise (in other words it sounds like its going hard, but its not). i also recently installed a pod filter, and ive only really noticed it after that becuase ive started revving it up more becuase of the noise. I've triple checked all air intake connections etc so it cant be that but maybe?

And also, is the stock timing for a RB30E 15 degrees BTDC?

Edited November 8, 2006 by rorz

[SKiT_R31]

Thanks for the suggestions SKiT_R31 i'll look into that

And yeah sorry i maybe didnt make it clear the exhaust im talking about is the Rb20DE from a GT Passage (jap spec).

The power loss doesnt seem to have a miss associated, the car just pulls up to about 3 - 3.5rpm then after that it just stops pulling and makes a nice exhaust/air noise (in other words it sounds like its going hard, but its not). i also recently installed a pod filter, and ive only really noticed it after that becuase ive started revving it up more becuase of the noise. I've triple checked all air intake connections etc so it cant be that but maybe?

And also, is the stock timing for a RB30E 15 degrees BTDC?

yeah stock timing is 15degs

i knew he was talking about a HR31

you could have a gunked up cat also, if it doesnt like revving.

I would go a 2.5" mandrel (or 2.25" if you have to...) with a highflow cat, a muffler and a resinator, with a nice set of extractors, that should make it pull a bit harder for a start.

as for drone, its all in the mufflers...

[rorz]

Sweet as cheers for the replies.

And quickly, what is the incriments in which the timing marks go up in? (how many degrees between each timing mark on the belt? 2 degrees isnt it?)

Cheers

[SKiT_R31]

Sweet as cheers for the replies.

And quickly, what is the incriments in which the timing marks go up in? (how many degrees between each timing mark on the belt? 2 degrees isnt it?)

Cheers

nuh mate its 5 degrees, starting on zero (being red, the rest are white), so if its sitting on the forth notch its on 15 degs.