VWDiesel.net The IDI, TDI, and mTDI source.

Engine Specific Info and Questions => IDI Engine => Topic started by: motomike33y on March 15, 2011, 10:14:58 am

Title: Any advantage to larger/straight pipe on 1.6 NA?
Post by: motomike33y on March 15, 2011, 10:14:58 am
I've read about the advantage w/turbo to increasing the exhaust flow, but is there any advantage to putting 2.25 straight pipe on regular 1.6 NA engine?  not trying right now, but thought for the future.  insight appreciated.  thanks.
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: ibizz on March 15, 2011, 10:18:15 am
yes at least breath more easy , and increase torque
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: Bugsy_malone 666 on March 15, 2011, 11:04:25 am
To Some extent the NA Diesel should be treated in a similar manor to a Gas engine with regards to tuning in some respects, better gas flow in and out of the engine and a little extra fuel will help you out. I am not sure though if a proper 4 brand manifold with give you much benefit though, but certainly a less restrictive exhaust will help. They do become very loud though!
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: R.O.R-2.0 on March 15, 2011, 11:16:08 am
the toilet bowl downpipe is one of the biggest restrictions..

get a better manifold, like a dual downpipe unit, and run a muffler..

i had a glass pack on my rabbit, and it was RETARDEDLY loud.. well, that may have had something to do with the header too..
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: rodpaslow on March 15, 2011, 02:01:02 pm
I go with ROR, I had a hole in exhaust a year ago.  If you thought a gasser was loud with a straight-pipe, just wait till you do a 1.6 NA.  You will need serious ear plugs to drive the car. 
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: R.O.R-2.0 on March 15, 2011, 02:20:16 pm
a flowmaster 40 or 50 series would probably sound pretty bad ass on a VW n/a
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: motomike33y on March 15, 2011, 07:03:40 pm
yeah, it's loud enough now with the normal noise from the engine compartment-don't know if I could handle having to wear earplugs.  Does muffler assist or hinder with the larger diameter pipe?
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: 8v-of-fury on March 15, 2011, 07:06:04 pm
currently have a straight pipe on my 1.6 N/a with a glass pack. Oh my gawd does it sound raspy when you get her up in the revs. 4000 sounds superb!
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: RabbitJockey on March 15, 2011, 07:12:31 pm
the toilet bowl downpipe is one of the biggest restrictions..

get a better manifold, like a dual downpipe unit, and run a muffler..

i had a glass pack on my rabbit, and it was RETARDEDLY loud.. well, that may have had something to do with the header too..

diesels actually had the bigger toilet bowl, i think the biggest restriction is the pin prick stock exhaust, 1 5/8"s, what a joke, also the stock intake setup is very restrictive, both were designed to reduce engine noise.  i bet an na diesel, with governor mod (or especially with a giles pump), a bigger exhaust, and gas intake manifold would be equal or better than an equivalent sized gasser as far as performance, actually i think tylers dyno already proves that.
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: 8v-of-fury on March 15, 2011, 07:14:26 pm
Trev i do believe you are right, Tyler's car was a Giles pump, stock intake stock exhaust. And he pulled some mad power throughout the whole range.
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: rabbitman on March 15, 2011, 07:24:12 pm
The guy that's making my valves told me that a rabbit with a ported NA diesel will keep up with a gasser rabbit.

If you are never going to get a turbo then I would NOT recommend going larger than 2", maybe 2 1/4" at the biggest. My NA rabbit has is 2.5" all the way back with a homemade muffler by the shifter and a thrush baffle one in the rear and the noise, while not painful, will leave my head ringing after less than a 100 miles. When I had the vnt15 installed and NO muffers it sounded awesome and wasn't too loud at all.
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: R.O.R-2.0 on March 16, 2011, 08:42:20 am
currently have a straight pipe on my 1.6 N/a with a glass pack. Oh my gawd does it sound raspy when you get her up in the revs. 4000 sounds superb!

hondas are raspy.. VW diesels are rappy..

the pipes rap on a diesel..

and they start rappin at about 1200rpms.. least they did on my car.

i couldnt shift, or take off without rappin my pipes..

almost the same setup as jeremy.. a header, feeding the stock exhaust system, and then a glasspack at the end..
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: R.O.R-2.0 on March 16, 2011, 08:44:52 am
The guy that's making my valves told me that a rabbit with a ported NA diesel will keep up with a gasser rabbit.

If you are never going to get a turbo then I would NOT recommend going larger than 2", maybe 2 1/4" at the biggest. My NA rabbit has is 2.5" all the way back with a homemade muffler by the shifter and a thrush baffle one in the rear and the noise, while not painful, will leave my head ringing after less than a 100 miles. When I had the vnt15 installed and NO muffers it sounded awesome and wasn't too loud at all.

my n/a diesel would almost keep up with my 85 GTI.. so i bet it would keep up with a stock rabbit. i had no porting or anything done, it had a header, a better air intake, a cranked up fuel pump.. and probably a few other little things i cant remember..
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: motomike33y on March 16, 2011, 12:47:47 pm
why would the straight pipe be quieter w/turbo than without?  or is an esthetic thing that the turbo noise blends in and the exhaust note isn't noticeable?
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: RabbitJockey on March 16, 2011, 02:28:30 pm
why would the straight pipe be quieter w/turbo than without?  or is an esthetic thing that the turbo noise blends in and the exhaust note isn't noticeable?

turbos just act as a muffler, the first thing i noticed after my turbo swap was how much quieter it was.  and then how much faster it was haha.

tyler did 48whp and 70wtq if you figure 18% drive train loss thats 56whp and 83wtq, looks like 1.6-1.7 gassers are anywhere from 60-75hp.  so some what comparable considering the vw diesels have a tiny exhaust and intake

Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: maxfax on March 16, 2011, 04:05:40 pm
Stock toilet bowl opened up to match the 2" pipe, and some variety of cheapo turbo muffler and I've never looked back..  Better power and cooler temps while pulling hills and passing..  Fuel mileage didn't change noticeably...  IT is a tad loud, but tolerable.. A glass pack or resonator in the system with the muffler would probably be the ticket...
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: motomike33y on March 17, 2011, 06:13:32 am
I may look to doing something like that this summer, after my other projects.  I may try to get 81 jetta w/dasher engine running since I've learned more about IP timing from this group.
Title: Re: Any advantage to larger/straight pipe on 1.6 NA?
Post by: R.O.R-2.0 on March 18, 2011, 02:28:46 pm
why would the straight pipe be quieter w/turbo than without?  or is an esthetic thing that the turbo noise blends in and the exhaust note isn't noticeable?

when my car had an open downpipe, and it was n/a, it would ring your ears..

when i put a turbo on my car, i still had an open downpipe, but it was quiet enough to carry on a conversation in the cab..

plain and simple, turbos quiet these things down ALOT. until the wastegate opens!