Best exhaust manifold for stock 1G head?

[leakyfaucet]

As the title suggests, what would be the best exhaust manifold for a stock 1g head?

Really, what I want to know, is which manifold's runners would best match the ports on the head? I can't see a ported SBR manifold, with runners that are incredibly huge compared to an evo manifold, lining up correctly with the head.

Everyone else seems to go by the "bigger the better" ideology, but I don't think this would be the best idea.

 

[Slowboy]

We have about 10 Evo III manifolds here as well...

PS.. our manifold lines up perfectly, on NEDSM someone did some measuring, etc.. but I do not have the link right now..

Regards

Mike Huml

 

[leakyfaucet]

We have about 10 Evo III manifolds here as well...

PS.. our manifold lines up perfectly, on NEDSM someone did some measuring, etc.. but I do not have the link right now..

Regards

Mike Huml

If your big manifold lines up correctly then the evo manifold can't possibly. Right?

 

[Slowboy]

If your big manifold lines up correctly then the evo manifold can't possibly. Right?

are you talking about???????

If you have not noticed it is a copy of the EVO III manifold..... only difference is we copied one of our versions that was already ported and had the step removed.....

Regards

Mike Huml

 

[Chargedawd]

here is that very thread:

http://newengdsm.org/forums/viewtopic.php?t=1158

 

[leakyfaucet]

are you talking about???????

If you have not noticed it is a copy of the EVO III manifold..... only difference is we copied one of our versions that was already ported and had the step removed.....

Regards

Mike Huml

Huh? It says on the website "the runners are larger"...
http://www.slowboyracing.com/Exhaust/Exhaust manifolds/Evo Exhaust manifold/sbrcast.html
Nevermind, anyways, this is what I was getting at:

If a manifold does line up, what would be the point of porting the runners? The head ports will still be small, and the exhaust would just be dumped into this extra open space, with no smooth transition from head to manifold.

So, with that in mind, which manifold's runners would best match a stock 1g head's exhaust port? A 2g manifold, an evo manifold, or something else?

One last question: Are the exhaust ports on a 1g head the same diameter as a 2g head?

 

[Tallen]

With the tiny 1G ports, there is only so much you can do. A 2G manifold would help some, but in all reality, you should get your head ported.

 

[Tallen]

If a manifold does line up, what would be the point of porting the runners? The head ports will still be small, and the exhaust would just be dumped into this extra open space, with no smooth transition from head to manifold.

They port it with the expectancy that you will get your head portmatched.

 

[leakyfaucet]

They port it with the expectancy that you will get your head portmatched.

But think of all the people that buy ported 2g manifolds with the stock head...

Does anyone have an answer? What manifold would best match the 1g port size?

 

[boostedinaz]

I know what you are saying, but look at it this way. If you hold a funel to yor mouth and you blow out is there restriciton because of the small hole??? No becasue the hole is just the begining. With you thinking we should only run 2 inch exhaust, becasue the two exhaust valves only make up about a 2 inch area.

Any of the the mani will work just fine. I would get an EVO or wait until the Slowboy one has been tested and proven a bit more. It looks like a good design and I dont doubt it wont work, but give it time. The HP increase will be so small that it wont even be worth the discussion.

Michael

 

[boostinup97]

I ran an evo manni and i had 0 problems with it lining up perfectly with the head and didn't have a single leak what so ever

i recommend running the evo mani

 

[leakyfaucet]

With you thinking we should only run 2 inch exhaust, becasue the two exhaust valves only make up about a 2 inch area.

No, because as the exhaust cools it loses velocity and needs more room (Oversimplification) and there are generally smooth transitions to the larger diameter exhaust.

The only thing that worries me is that if I did put a manifold with bigger runners than my head ports, it would lose velocity, as the there would be no smooth transition to the larger runner, just the port running into a huge open space.

I've included two poorly drawn pictures to illustrate my point. Wouldn't it make more sense to have the "good manifold"?

 

[leakyfaucet]

I ran an evo manni and i had 0 problems with it lining up perfectly with the head and didn't have a single leak what so ever

i recommend running the evo mani

Thanks for the advice. Was this a 1G or a 2G head? (is there a difference on the exhaust ports?)

 

[Slowboy]

Or....

Get your 1g head ported, throw a stock Evo III manifold on, and have a little problem called reversion... hence why our manifold was cast the way it was...

If you have a bone stock head/ car call up and order an EVO III manifold, at least until Mitsubishi raises the price 30% this fall...

Regards

Mike Huml

 

[entropy138]

No, because as the exhaust cools it loses velocity and needs more room (Oversimplification) and there are generally smooth transitions to the larger diameter exhaust.

Actually, exhaust cools quicker the more room it has. If cooler exhaust needed more room we'd all be running larger than 3" exhuasts. You would retain better exhaust velocity if your exhaust slowly got smaller towards the end, however, we don't do this because it restricts the amount you can flow.

This entire argument about the runners being larger than the head isn't really worth your time. You have a turbo in the exhaust stream which is a huge restriction to free flowing exhaust. This creates a large amount of pressure in the mannifold that really negates the issue of exhuast velocity. As the air is pumped out of the cyl it runs into this high pressure area and is like hitting a brick wall. So the fact that the transition isn't "smooth" really isn't that big of a deal, where as the advantages of having more room far outway that step in your "bad manifold" drawing as it helps to aviod reversion as stated above in the example of a ported head w/ tooo small of a manifold for what the head can flow (or too high of a pressure outside the cylinder / port to allow for proper evacuation of exhaust gasses).

So, in summary, unless you're worrying about a N/A car and keeping maximum exhaust velocity, don't worry about an abrupt step to a larger mannifold because your turbo is creating more problems than you can even begin to attempt to remedy by having a "perfectly sized" mannifold.

 

[GSX_RCR]

So, in summary, unless you're worrying about a N/A car and keeping maximum exhaust velocity, don't worry about an abrupt step to a larger mannifold because your turbo is creating more problems than you can even begin to attempt to remedy by having a "perfectly sized" mannifold.

Ding Ding! Exactly what I was thinking when I opened this thread and read the first post.

Don't worry about the "slight" transition step between the exhaust port and manifold...if FLOW is your concern, then let me remind you that there's an even BIGGER obstruction in your exhaust gas flow just a little bit further....mainly a huge friggin turbine fan! :laugh:

BTW, anybody who's anybody wouldn't be working with stock ports...much less stock anything.

 

[leakyfaucet]

BTW, anybody who's anybody wouldn't be working with stock ports...much less stock anything.

That's a pretty ignorant statement.

 

[ITSME4G63]

I got a ported evo manifold Im going to put on , but If I didn't I would get a sbr one, cuz they always have the best shit. Especiually when you're lookin for oem type stuff, like Im looking for a 1g oil pan(6 bolt) and these guys ####ing sell a brand new oem type for 100$ I mean shit thats a pretty good deal.

 

[entropy138]

Isn't most the OEM stuff they carry Top Line? I haven't heard too much good about it other than prices.

 

[ZyklonBZombie]

I ran an evo manni and i had 0 problems with it lining up perfectly with the head and didn't have a single leak what so ever

i recommend running the evo mani

i too am running a evo manifold with no problems ...

 

[turbo90gsx]

When some of you guys swapped the stock 1st gen to a ported EVO, did you see any difference in spool up or aceleration? Just curious, because I've been looking at the Slowboy mani VS the EVO mani and I think the EVO will get my business. The Slowboy mani just seems over kill for a stock head with a 14b, or is it?