exhaust recommendations.

[modular9]

well the weekend is coming to a close and i have found another reason to replace my exhaust system! at last check i have 17 holes ( 3 - 5 mm diameter ) just after the stock exhaust manifold becomes one 1 .75 inch pipe. 

 

So I am going to go with some hm headers for sure. Now what i need to know is what recommendations for pipe size and also more importantly muffler choice. The last time i had to think about exhausts it was v8 spec and that was headers into a single 2.5 inch pipe into a single flowmaster muffler. ( yeh it was loud! )

 

My current engine spec ( as per previous owner )

 

P90 pistons and a 240 crank. ( have receipts for these )

flow ported top head ( e88 head where the stamping is the larger stamping of e88 )

I think this makes it a stroker but i have heard things like i need a n42 head instead of an e88. Short of whipping off the head and sump and checking the marks I dont know for sure. She sure has some serious get up and go that i dont remember my dads stock 280zx having.

 

I have mismatched jag double SU's ( took em apart and seem to be the same inside with the same casting marks ) sitting on a stock intake manifold. I am almost 100% sure i am going to get triple dellorto's or webers ( expensive but she is worth it ! ) down the track after some suspension mods.

 

So the questions are these

1.

2 inch pipe or 2.5 inch . I dont want to "over exhaust" the car.Do the L-series of engines like a lot of back pressure or more straight through?

 

2.

What is the best muffler to use? I am partial to flowmasters as I have used them before. Do i need 2 mufflers like my current system or can i get away with good single one?

 

Thanks for taking the time to read this. Someone told me to sort out the exhaust before going all out on a tune job. Which is my next job.

 

Mike

 

 

[Toecutter]

Hi Mike,

 

I piss farted around with a few combos before getting mine right with the L26. Started off installing headers with 2.25" pipe straight through to one of those big fart can exhausts a cat can crawl into. No baffles you could pick it up and look straight through it. Man was it loud, no bottom end power either.

 

I installed a "hot dog" type middle muffler, (not sure what they are really called), and that helped but still way to loud and ridiculous resonation at 100km/hr or 2500rpm. Some time later got rid of the the silly looking 3" "cat house" muffler and got a muffler with a proprietry name of "Turbo FLow" with a dump pipe to help with the fumes and a smaller middle hot dog type.

 

I'm really happy with it now. Still pretty loud and aggressive top end and a great note and tough enough down low also. Got a lot of bottom end power back too!

 

Good Luck

Sulio

[modular9]

hello Sulio,

 

So it looks like 2.25" system with a turboflow + hotdog . I had a look under Christine ( name of car not a young lady ! ) and she doesnt look like she could take a big flowmaster.

 

Did you have to add the hotdog for registration/police purposes ? I would much prefer to have a single turboflow muffler with nothing in the middle of the system i know the hotdog adds a lovely growl but i wouldnt want to add it if it impunes on performance.

 

thanks sulio for your system specs.

[sco_aus]

I know here in canberra due to the age of the car (doesnt matter about the engine for some reason, but I dont have to have a cat converter.  Not sure about Vic and others.

[Toecutter]

Reason for the smaller hotdog was the resonation. Man it gets mind numbing on a long drive. It's still pretty loud in the car when driving around town and just putting along but I don't mind that growl just don't like it when it feels like there is a vacuum cleaner working next you at 100km/hr. I think the L series motors have a nice note to them in general it just comes down to get rid of any resonation at freeway speeds. Some exhaust pros here might be able to shed some light on this annoying occurance and how to avoid it on your first set up without restrciting heaps!?

[nat0_240_chevZ]

cats are for more modern cars from about mid 80's onwards!!!!! for unleaded too also i think!!

 

well my experience tells me to stay with simarlarly sized mufferls and "resonanor' (the hot dogg thing you guys speak of)

 

run extractors fine, 2.25' is most ideal, 2.5" if you run continuos high revs ie racing/sprinting with the l28.

No 2.25 will not hurt the flow what so ever, (REMEMBER only 1 cyl is exhausting at any 1 time, sothe size of your header pipe is all you really need for the whole system, V8's are different however as they have exhaust overlap)

 

its the length of the dogg that dictates frequency change ie resonance, measure the stock dogg and muffler and replace with straight through flow iw turbo muffler etc.

 

from memory they are both 12" long, i recommend highly of maintaining the 12"dogg mid way through the system, keeps that resonance thing sulio talks about to a min (as you cant get rid of it all together unless you silence the whole system with 2 baffled muffs!!)

 

trust me on this one, i had i very high revving l24 worked off its titas and boy did she growl, sounded like a touring car when opend up, but a beautiful note like a 6 cyl symphony.

 

hope this helps, but would also be interested in what others think....any other q's welcome

 

nato

[PZG302]

Not really a help for your setup by my injected L28 that I believe is stroked, haven't taken the bottom off to confirm yet, runs hand made extractors, 3 into 2 into 1, then into a 3" pipe, one muffler, cant remember the brand, but cost a fortune, and then exits out the right hand side level with the rear of the door.

 

Note is loud enough to scare the neighbours when I had it at home in the garage and bring people out of their houses to have a look when doing a shakedown run in the cul-de-sac before putting it on the trailer . At the top end it was designed for I have been told it sounds like a swarm of bikes, I have always gotten compliments on the note of the car. I think I have some pictures at home if you need to see the setup.

 

 

[modular9]

Well we had a RACQ motorfest thing on the weekend (rainy days on either side of it-  beautiful day ) and the qld zed car club was there with 3 cars ( g- nose 240z rb series engine , 240z lightened racer with fibre glass panels , and a very nice slightly at least he was a little cagey  modded 240z sitting on mini( super) lites ) and the general consensus was 2.25 inch with the hotdog and a turbo flow exhaust. So nat0_240_chevZ seems to be on the money, must be a semi common knowledge type of thing.

 

So she is going in this week to have her breathing sorted after the auto electrician re route the lights off the main fuse box. ( something i do on every early car i have ever owned )