Split Dump Pipe Success Story

[rmahnovetsky]

I have been reading so much about the split dump pipe and how they are superior to the 3" dump pipe. Statements like "they reduce turbulence when you are on boost, therefore reducing backpressure", "10kw gain", "should notice a big difference in the top end of the rev range". These statements and theories behind it sold me. So I though I would give split dump pipe a go.

Since I already had a 3" dump, I decided my cheapest option would be to modify it to a split. The idea behind my design would be to keep the wastegate and turbine gases seperate for as far as possible. This would reduce as much turbulence as possible on the turbo. I made a seperator in the recess of the turbo which keep the gases seperator through to the dump. The split pipe then joined just before the cat. See my pics for the mod

results:

First design suxed: My seperator was to thin (1.4 mil) and the wastegate gases bent the metal and my car actually went worse.

Second design: I fixed the seperator with 4 mil metal. Now for the real results:

The origianal 3" dump used to drop off acceration at about 6.5 k. The new dump did not, it actually increased in acceration. Very nice.

I noticed better acceration throughout the full on boost range. But mostly after 6K, this showed the biggest gains. FYI: I was using stock boost i.e. no bleeder. I was hitting about 9.5 psi

3rd gear seemed to be the real winner hear. I noticed a really Big difference in acceration in 3rd gear. usually when I drag a car if they accerate the same as me in 2nd then my third is slighty better. But not now 3rd really pulls now. I got to test this out on a maloo ute, and a silvia. Both where slighty slower than my skyline in 1st and 2 but 3 I pulled away very quickly. 3 cars length in that gear alone. I reckon without the split maybe 1 car length if lucky...

On stock boost (9.5) it feels like it accerates quicker than when I had 11 psi with the original 3" pipe.

Split dump pipes rock!!!!

[drewr33]

Thats awsome. I cant wait to upgrade my exhaust to a full 3inch.. Will defently go the twin dump after reading this and other successfull stories.

[siddr20]

cant wait till i purchase a spilt system as well.. if only i had money!!

[rmahnovetsky]

I wish I bought a 3" split from the start. Oh well I got to practically see the difference between the two. When I went down the quarter I got a 14.9 on my stock car. With stock boost and the full 3" exhaust with split dump it should be in the 13 easily . I ran a a 14.051 with the original 3" exhaust and 11 psi. And this feeels noticably faster.

[paulr33]

i disagree, you will need around 200rwkw and a fairly good setup car to run 13 flat

[rmahnovetsky]

in the 13s not a 13

[jazza08]

Good to hear that as im goin to put the few hundred extra needed into a split as ive only read/heard that they are much better than the cheap open bell mouth 3' dumps!

[rev210]

i disagree, you will need around 200rwkw and a fairly good setup car to run 13 flat

Nah. I reckon a nice average power 160rwkw from 4000rpm to 7000rpm will cut a high 12. The old R33 did 13.3's @106mph 2.3 60ft with that power. A 2.1 60ft would have nailed a 12.9 pretty easy. Thats a car with that average power and a peak of only 175rwkw. 205 tyres too.

[Syphon]

Didn't happen to take any pics of the divider inside the dump did you?

Would be interested to see if I could just about do this to my existing 3" dump

[rmahnovetsky]

I'll take a pic for you when I take it off again to paint it.

[Anquetil]

What was the eventual length of the split pipe? It looks longer than usual?

[rmahnovetsky]

I didn't measure it. But it is nearly as long as the dump. I wanted to make it as long as possible to keep the turbulence as far away from the turbo as possible. Boost holds quite well now too.

[Scooby]

champion, good result. now, how about doing some for a gtr...

[Syphon]

Thanks champ, a pic would be sweet

[Mr_G]

Hey guys, I run one of these split dump & front pipes which I purchased of CES about 2 years ago.

In my opinion, they are awesome! My car spools pretty quick, this is on a standard R33 GTST turbo on my RB25DET.

Other mods include:

FMIC

Exh cam gear

Turbo back exhaust (obviously split dump & front)

PFC

Bleed valve set @ 13psi

Pod in box with CAI

Hard pipe between turbo and AFM

If you look closely at the graph, it makes 100rwkw around 2850rpm

Just click on the attatchment to view it, it will def load up. Sorry bout the quality, but dont ever lend people digital cameras, they come back not working even though they were well looked after???

[Syphon]

Thats one impressively smooooooth power curve!

nice work

[chzz]

I recently bought a split dump pipe from BTMBL and spend $450 thinking its good and better than the others on the market.BUT unfortunatly it was a unproffessional job the welding were shit and i had to grind them and was not a direct fit had to modify front pipe because didnt fit the cat stright and it was 2 to 3 inches away from the straight fitting. After all that i thought i will at least feel a big gain that i feel but at the end its nothing big.Only difference is it comes to boost quicker.

[rmahnovetsky]

I recently bought a split dump pipe from BTMBL and spend $450 thinking its good and better than the others on the market.BUT unfortunatly it was a unproffessional job the welding were shit and i had to grind them and was not a direct fit had to modify front pipe because didnt fit the cat stright and it was 2 to 3 inches away from the straight fitting. After all that i thought i will at least feel a big gain that i feel but at the end its nothing big.Only difference is it comes to boost quicker.

I felt a noticable difference with my split dump and so have others. So it seems you would have a problem somewhere else down the line. Possibly the rest of your exhaust and cat is std or maybe your in RR. The split definitely works and you should atleast notice a difference after 6.0k....

[chzz]

I didnt say it didnt make any difference it made a diiference but not as much as everybody talk here....I had a full bell mouth dump pipe and 3.5inch system but i actually chucked it on the dyno today and found out its only a 4KW gain. This was done in a one of the best work shops in melbourne and everything was done properly.SO PROVED NOTHING WRONG WITH THE CAR OR THE EXHAUST SYSTEM.

[Miller the hoon]

Split dump is that the same as intragrated waste gate in an exhaust system?

james