Jump to content
SAU Community

Recommended Posts

Hi Guys,

I've got someone about to start on designing my exhaust manifold for my R33 GTS-t, which willl be housing a GT30 series turbo. I was after some info on what people think the best design is in terms of materials and length of the runners.

Currently the idea is to have it made from mild steel, as I hear alot of people with the stainless steel ones have cracking issues. I'm not sure if having them tuned length really makes alot of difference or not, any suggestions, preferably from first hand experience. I was also planning on having it ceramic coated, as we can now get it done here in Perth, has anyone done this and compared it to heat wrap etc.

Any comment will be appreciated, as I don't want to have a pooorly designed manifold, or one that won't be up to the task. Aiming for 450rwhp, and yes all the other things have/will be done to the engine before the turbo is in place.

See'ya:burnout:

Link to comment
https://www.sau.com.au/forums/topic/7272-exhaust-manifold-design/
Share on other sites

  • Replies 45
  • Created
  • Last Reply

Top Posters In This Topic

EDIT: got off on a tangent, so I'll start again,

I have owned a car with mild steel headers, and it performed fine, weight less than stainless (can't be a bad thing) and had good heat transfer qualities (dont know how it would compare to stainless).

Haven't used stainless, but if you are going for ceramic coating, the advantages of stainless (look good and dont rust -are there any others?) will be completely negated I would think.

Steve

Thanks for the reply Steve, I was beginning to think no-one had done this. I've heard that due to the heat transfer of the stainless it becomes brittle after prolonged use, heating and cooling. I believe that if you have it sand blasted to destress the stainless then it will perform better.

The mild steel sounds the go as it can withstand the high temperatures better, and once its ceramic coated should look quite nice.

Any opinion of tuned length vs not, it just cost more to have a custom tuned manifold and I'm not sure its worth the money.

See'ya :burnout:

I believe (perhaps very wrongly) that tuned length offers more than just a really nice note to the exhaust.

Having tuned lenght, means more equal flow and heat characteristic from the cylinders, reducing back pressure due to less turbulence = higher output with less stress on the motor and probably a quicker spool up. Is the price difference that much? Tuned length has been around for a long time.

Steve,

I can appreciate the difference in theory, pretty much the same as any tuned length extractor, with the air arriving at the same point at different times so as not to create turbulance and back pressure.

I'm just wondering whether anyone has actually tried both ways and noticed any real difference. The price is probably only $200 more, but if it makes f#ck-all difference then I can spend that on getting the block ported.

I'm after about 450rwhp, I don't know if the tuned length is really for high horsepower engines or whether I will see the difference on a mild-tuned engine.

Thanks for the help.

See'ya:burnout:

Steve,

I'm hopefully having anything that I can get done to it, as I don't really want to ever have the head off again. Forged pistons going in, overboring the cylinders, shotpeening the rods, balance the crank and port and polish the head. Yeah it does seem like alot of power, but I think it should still be quite responsive and street drivable.

I suppose if I'm going to the extent of maximising the airflow everywhere else I should't scrimp on the exhaust manifold. It's just that it all cost so much.

See'ya :burnout:

Yeah but having a beast and knowing how to drive it are two different things, judging by my pathetic 13.9 at the drags last night. I feel I'm letting the car down, it probably deserves a better owner, but I do spend a shitload of money on her, even more then my ex-girlfriend. The car doesn't bitch as much either.

See'ya:burnout:

Don't worry about letting the car down, as long as you're having a good time that is all that really matters. Plus there is the added bonus that with 450 neddies going onto the deck, some people may be thinking you are just out there to get the jump on the burnout demos - lol

to add to this thread -

I have a Garret T66 turbo mounted onto a custom exhaust manifold. this is in mild steel then HPC. It achieves the necessary function without any problems of cracking or overheating. I would have to say that i haven't had a stainless steel manifold made, but 4 me it was a cheaper alternative. the price can be relativeli cheap depending on who u commision to construct the manifold. I'll enquire 4 u.

N1K

GT N1K,

I'm definately thinking of the mild steel over the stainless, I know a few race cars with stainless and there's have cracked. I will also pay that bit extra for the tuned length, even if I'm still unsure about the possible benefits.

Thanks for the help, how is your car going, has it been dynoed yet?

See'ya:burnout:

Where in Perth can you get the ceramic coating done? I was planning on getting my dump pipe HPC coated (via eastern states) but if ceramic coating is a local offering I would be interested in that.

Sounds like your car is an absolute friggen monster... would love to see it go through its paces on the track :P

Conrad

Slayer,

Will be a monster, its not there yet, but over the Christmas/New Year quite a bit of the internal work will be done.

I will find out about the ceramic coating, hopefully tommorow, and then I'll let everyone know.

See'ya:burnout:

I run stainless extractors and 1 and 6 cracked from the head fange and had to be re-tigged...

If your going to throw a fortune at it .... do whats "theoretically" right and blow the $200 on the tuned length if you think everyone else who make performance manifold are wrong ... then dont

but whatever you do set the external gate up in an appropriate place, clearances become and issue

I couldnt have it dynoed yet. They couldn't fit it on the dyno at speedworks as it was too wide to fit the Dyno pack onto my hubs. So now i gotta wait til 2morow 2 c if any other dynos can fit my car without hitting the body skirts. & rising the car is out of the question as its at its max height. The anticipation is killing me!!

N1K

Shit N1K, the anticipation is killing me too, you must be ready to have a heart attack. I'm not surprised that your having difficulty with such a wide body kit. It does seem sad that the dyno doesn't take into consideration for cars with a bit of bulk to them.

Hope you get it sorted soon.

MrMayham,

I will be get it tuned length, and thats the reason I didn't want stainless, cause they tend to crack.

See'ya:burnout:

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • I guess one thing that might be wrong is the manifold pressure.  It is a constant -5.9 and never moves even under 100% throttle and load.  I would expect it to atleast go to 0 correct?  It's doing this with the OEM MAP as well as the ECU vacuum sensor. When trying to tune the base map under load the crosshairs only climb vertically with RPM, but always in the -5.9 column.
    • AHHHH gotchaa, I'll do that once I am home again. I tried doing the harness with the multimeter but it seems the car needed a jump, there was no power when it was in the "ON" position. Not sure if I should use car battery jump starter or if its because the stuff that has been disconnect the car just does send power.
    • As far as I can tell I have everything properly set in the Haltech software for engine size, injector data, all sensors seem to be reporting proper numbers.  If I change any injector details it doesnt run right.    Changing the base map is having the biggest change in response, im not sure how people are saying it doesnt really matter.  I'm guessing under normal conditions the ECU is able to self adjust and keep everything smooth.   Right now my best performance is happening by lowering the base map just enough to where the ECU us doing short term cut of about 45% to reach the target Lambda of 14.7.  That way when I start putting load on it still has high enough fuel map to not be so lean.  After 2500 rpm I raised the base map to what would be really rich at no load, but still helps with the lean spots on load.  I figure I don't have much reason to be above 2500rpm with no load.  When watching other videos it seems their target is reached much faster than mine.  Mine takes forever to adjust and reach the target. My next few days will be spent making sure timing is good, it was running fine before doing the ECU and DBW swap, but want to verify.  I'll also probably swap in the new injectors I bought as well as a walbro 255 pump.  
    • It would be different if the sealant hadn't started to peel up with gaps in the glue about ~6cm and bigger in some areas. I would much prefer not having to do the work take them off the car . However, the filler the owner put in the roof rack mount cavities has shrunk and begun to crack on the rail delete panels. I cant trust that to hold off moisture ingress especially where I live. Not only that but I have faded paint on as well as on either side of these panels, so they would need to come off to give the roofline a proper respray. My goal is to get in there and put a healthy amount of epoxy instead of panel filler/bog and potentially skin with carbon fiber. I have 2 spare rolls from an old motorcycle fairing project from a few years back and I think it'd be a nice touch on a black stag.  I've seen some threads where people replace their roof rack delete with a welded in sheet metal part. But has anyone re-worked the roof rails themselves? It seems like there is a lot of volume there to add in some threads and maybe a keyway for a quick(er) release roof rack system. Not afraid to mill something out if I have to. It would be cool to have a cross bar only setup. That way I can keep the sleek roofline that would accept a couple bolts to gain back that extra utility  3D print some snazzy covers to hide the threaded section to be thorough and keep things covered when not using the rack. 
    • Probably not. A workshop grade scantool is my go to for proper Consult interrogation. Any workshop grade tool should do it. Just go to a workshop.
×
×
  • Create New...