Mazda Rotary Club

Cars by Model Type => 3rd generation RX-7's => Topic started by: Cashpoint on June 04, 2010, 03:52:10 PM

Title: Thicker exhaust manifold needed
Post by: Cashpoint on June 04, 2010, 03:52:10 PM
Got a Gt4088 single on the car with an eBay manifold which though it does the job is to thin and with my street port is rather loud. So I want to change it for a thicker better quality manifold, anyone got and recomendations and where to get them from?
Title: Thicker exhaust manifold needed
Post by: turbotoaster on June 04, 2010, 06:18:21 PM
your assuming that running a thicker manifold will make your car quieter?
Title: Thicker exhaust manifold needed
Post by: Rotormotor on June 04, 2010, 11:24:38 PM
I have an ebay mani on my streetport and it sounds like it\'s blowing. was driving me crazy trying to find the leak.
Turns out it\'s not blowing but it\'s the ticking noise on the thin stainless manifold walls.
Title: Thicker exhaust manifold needed
Post by: turbotoaster on June 04, 2010, 11:25:51 PM
if it works then just wrap it, surely that will keep any noise down
Title: Thicker exhaust manifold needed
Post by: Cashpoint on June 05, 2010, 10:47:37 AM
It does sound like it\'s blowing but knew it was the the porting but yes I was hoping to reduce the noise from the engine. As stationary the engine bay is louder that the exhaust.
Title: Thicker exhaust manifold needed
Post by: hairyhoover on May 01, 2011, 08:38:35 AM
Hi, what\'s the clearance like between the inner wing and the turbo?
I\'m picking a gt4088 up today and was expecting to have to mod my eBay manifold.

Cheers
Title: Thicker exhaust manifold needed
Post by: skybusr34 on May 01, 2011, 11:24:24 AM
sticking a cast manifold on will reduce the noise loads. they cheapy ebay jobbies are like 0.5mm thick . the cast ones are nearer 6mm.
Title: Thicker exhaust manifold needed
Post by: shaunwil on May 01, 2011, 12:03:18 PM
It could be an aspect of welded tubular manifolds. I\'ve got a very good quality one from A-spec in USA and it does the same thing. Seems to add occasion on mine when driving !

Shaun
Title: Thicker exhaust manifold needed
Post by: SiH on May 02, 2011, 07:46:10 AM
Wrap it ;) :)
Title: Thicker exhaust manifold needed
Post by: Cashpoint on May 02, 2011, 07:20:00 PM
Wrapping it didn\'t make much difference.

Gt4088 cleared without any problems
Title: Thicker exhaust manifold needed
Post by: stylus350 on May 02, 2011, 07:53:20 PM
Have you wrapped the downpipe? Before I went single fitting a stainless downpipe produced the same noise on the twins. It was less prominent than after the single but defo there. I think the quality (thickness) of the downpipe is just as responsible.

Had a premium stainless mani before and now an an ebay stainless mani. The sound you are talking about was there with both but may be slightly louder with the ebay one it\'s difficult to say without a back to back.

I\'ve got used to it, and to the point I quite like its errr.. individual sound?
Title: Thicker exhaust manifold needed
Post by: m1tch on May 02, 2011, 08:04:26 PM
Some of the thinner stainless steel is actually stronger than some thicker sort, so it all depends on what stainless steel is being used.
Title: Thicker exhaust manifold needed
Post by: hairyhoover on May 02, 2011, 09:54:01 PM
Quote from: Cashpoint;759572Wrapping it didn\'t make much difference.

Gt4088 cleared without any problems

How did it spool?
Title: Thicker exhaust manifold needed
Post by: Cashpoint on May 03, 2011, 09:04:23 AM
Positive boost by 2k and full boost at 3700 rpm
Title: Thicker exhaust manifold needed
Post by: Speedworks on May 03, 2011, 10:14:19 AM
I have thesame turbo with some kind of cheap China Ebay manifold.

Haven\'t driven it yet but when building the car/engine, the turbo hardly clears the chassis frame.

I have been lloking for a better quality/location alternative but haven\'t found one True, A-spec and RX7 store sell this turbo as a kit but the manifold on it self is rather expensive.

Conclusion, a friend of mine is now building me a custom one. with 2mm thick stainless steel tubing.
Title: Thicker exhaust manifold needed
Post by: Cashpoint on May 03, 2011, 11:03:39 AM
Quote from: Speedworks;759685Conclusion, a friend of mine is now building me a custom one. with 2mm thick stainless steel tubing.


My gt4088 kit came from the RX7 Store. How much is your friend asking for the manifold as if it thick than the one i\'m running i may be interested?
Title: Thicker exhaust manifold needed
Post by: Looksamc on May 03, 2011, 11:37:11 AM
Just found this on the net if its any help.

http://www.advancespeedshop.com/cast-iron-turbo-exhaust-manifold-9396-mazda-g17141z6002000-p-665.html
Title: Thicker exhaust manifold needed
Post by: raceralexuk on May 04, 2011, 11:56:16 AM
The one Jon (Atomicrex) sells on here are the best you\'ll find.
Title: Thicker exhaust manifold needed
Post by: jackaleks on May 04, 2011, 03:52:00 PM
(http://www.full-race.com/catalog/images/mazda-2.jpg)

Full Race  (http://www.full-race.com/catalog/product_info.php?cPath=1138_1139&products_id=1869)are probably the best product around, you have to pay for that though :(
Title: Thicker exhaust manifold needed
Post by: raceralexuk on May 04, 2011, 04:40:48 PM
Yeah that\'s pretty nice too.

It\'s twin wastegate flanges are strange though. Very unusual to see on a 13B, I can\'t imagine anybody runs enough boost to need two. Only usually seen on motors running over 3Bar, and it\'s not really viable to try to make a 13 run at that inlet pressure.
Title: Thicker exhaust manifold needed
Post by: fil_auto on May 04, 2011, 05:02:31 PM
FDUK me that looks nice, was gonna say it almost looks Ti with those welds / colouring... drool! ;)

V Pretty ;)
Title: Thicker exhaust manifold needed
Post by: turbotoaster on May 04, 2011, 06:30:11 PM
Quote from: jackaleks;760031(http://www.full-race.com/catalog/images/mazda-2.jpg)

Full Race  (http://www.full-race.com/catalog/product_info.php?cPath=1138_1139&products_id=1869)are probably the best product around, you have to pay for that though :(

for that money though id want a custom made one so that i knew my turbocharger fitted in the engine bay(wasnt touching chassis rail, LIM or filler neck

Quote from: raceralexuk;760057Yeah that\'s pretty nice too.

It\'s twin wastegate flanges are strange though. Very unusual to see on a 13B, I can\'t imagine anybody runs enough boost to need two. Only usually seen on motors running over 3Bar, and it\'s not really viable to try to make a 13 run at that inlet pressure.


whats the point in having a full divided flange and turbine housing if your going to let the exhaust gas mix before it gets to them?

also dont you understand what wastegates are for, they are to divert exhaust gas AWAY from the turbo so that it doesnt create to much boost pressure, the exact opposite of what your saying.

if the wastegates were to small you would get boost creep where as the engine rises which in turn pumps out more gas the wastegate flow would max out and more air would hit the turbine spinning it up more and creating more boost than you want
Title: Thicker exhaust manifold needed
Post by: raceralexuk on May 04, 2011, 06:45:39 PM
That\'s a bit of a strange/agressive way of replying to a post :3Confused
 
Anyway, what I meant was that the volume of exhaust gas on a single turbo 13B running at sensible boost is well within the volume of exhaust gas a normal wastegate can cope with, thus two are not necessary.

Also, keeping the exhaust gases from each rotor separate is not critical with these engines. Twin scroll turbos are being used by "us" because they\'re readily available not necessarily because they\'re best matched to the powerplant.
Title: Thicker exhaust manifold needed
Post by: turbotoaster on May 04, 2011, 06:55:00 PM
im sorry......\'not necessarily because they\'re best matched to the powerplant\'

have you seen the research and development mazda went through on the fc when it came to divided housings, ill see if i can find the SAE paper on it, i think mitch might have a copy

they gained greater spool and showed more power at the top end by keeping the exhaust pulses seperate.
i would say rotarys are the actual engine that gain most by being divided

put a turbo on a full bridgeport engine with a small single wastegate and ask it to run 10psi of boost, it will struggle, hence the need for either a large 60mm wastegate or 2 smaller 38/44mm wastegates, since i havent run a dual wastegate setup on a rotary i can only comment on what people have said, that was it was better at controlling boost and responce than a single large wastegate.
Title: Thicker exhaust manifold needed
Post by: jackaleks on May 05, 2011, 02:56:42 PM
whoa, where\'d the aggression in here come from?

raceralex: i\'m pretty sure FullRace\'s 13b manifold actually only has one WG flange, at least the only install pics i\'ve seen on RX7Club had two separate runners into one flange. i think the main advantage of having two would probably be boost control response, as you can have the wastegates pretty much on the manifold with no extra runner for the gas to have to travel down... that said, you could probably measure the difference in response times in milliseconds so totally academic!

EDIT: actually, for the money they\'re asking i wouldn\'t be surprised if you could specify stuff like single/dual WG flanges.
Title: Thicker exhaust manifold needed
Post by: hairyhoover on May 05, 2011, 09:22:28 PM
Quote from: Cashpoint;759680Positive boost by 2k and full boost at 3700 rpm

was this on a street or or 1/2 bridge??? what size exhaust housing where you using?
 
Im just in the process of building a engine for this turbo and after seeing the size of it was i worried about spooling with a large street port. I have a 1.19 exhaust housing
Title: Thicker exhaust manifold needed
Post by: Cashpoint on May 06, 2011, 09:41:14 AM
Running slightly smaller than yours, 1.06 exhaust housing on large street port