Considered one way, it is fair for header makers to claim big power gains versus stock manifolds, because nobody ports the manifolds. But it's now common for turbo guys to flip the truck exhaust manifolds. This is proven good past 750 crankshaft HP.
So, what about porting them? Is there any point? Is it difficult?
Well, I'm doing it.



third pic is blurry, sorry, but shows a tight short-turn that was well-raduised by me.
I'll do some polishing soon. Numbers will be much later.

 

back in the day this used to be done often for classes requiring stock manifolds. I know several vette old timers that had it done to theirs.

 

I doubt if you're ever going to see any type of HP gains just from porting stock 3rd Gen manifolds. You'll rarely see much in the way HP gains unless you run some long tube headers. (even shorty headers don't do much for HP gains) I personally wouldn't waste my time with it. I'd just wait until you could buy a set of long tubes for it.

 

those are not 3rd gen manifolds. it would be interesting to see if it makes anymore power in a ls based engine. looking at the wear marks it might!

 

Those are LSx manifolds, not 3rd gen SBCs

The most power made from longtubes is by the primary length and collector design, not so much the primary diameter. It does factor in, but is not as critical as the first two

Since they flow so well at stock and headers are relatively inexpensive (4th gens mind you) almost all go ahead and upgrade rather than investing extensive time porting them

 

Are you guys noticing where I specified the turbo?
Anyway, thanks for looking at the thread. And if you're interested, I dug this up: http://www.carcraft.com/techarticles...est/index.html

 

Anytime you reduce turbulance and make a it a smoother transition you pick up power. Just curious in how much..Maybe start with a deburrer and die grinder and the move to a flapper wheel??

 

I'm glad someone is on the same page as me. I don't use flappers, I use the so-called "tootsie-rolls". But Saturday night I broke my arbor, so no polishing until a new one arrives. All my info about my tools, carbides, techniques and so on are in my thread on porting SBC heads, which is a sticky in the swap forum.

 

That is an interesting article. I plan on running f-body manifolds or shorty replacement headers in the future. I am more concerned about ground clearance and exhaust location than peak power. I plan on following this thread.

 

I suppose I need to get pics showing the port mis-match. I'll just bolt the manifolds to the disassembled heads, then shoot pics through the valve seats. I wish I had some LS6 or LQx heads, so I could show those as well. But I sold my LQ4 heads. Figured I'd never need them, and aside from this, I don't.

 

On a turbo setup, the reduced turbulence and increased flow from porting can help reduce backpressure in the system. That is ALWAYS a good thing. Truck manifolds flipped have been used well over 1500 hp I do believe. I think they have been into the 7's with those things. Dont recall if they were ported or not, but porting can help some. If they werent ported, then I dont find the effort worth it. 1000+hp is more than enough for 99% of the street cars here or anywhere. There are a few elite vehicles out there well over 1000whp, its more common than it ever was but certainly 1% of the car population out there roaming the streets.

 

You usually type good stuff, but this time I think you contradicted yourself.
First, you type: "On a turbo setup, the reduced turbulence and increased flow from porting can help reduce backpressure in the system. That is ALWAYS a good thing." And: " porting can help some", but then the very next thing is: "If they werent ported, then I dont find the effort worth it."
If they made 1500 horses with un-ported manifolds, then ported may have resulted in 1600, with NO other changes. Durability would improve, too.
10 minutes per port for grinding, and another 5 for polishing, that's 2 hours.
Okay, newbs might need to double that time, but still, just keeping some of the heat out of the iron makes it worth it.
There's no point in ported or AFR heads if you're gonna use un-ported manifolds.

 

How do you feel about getting a manifold extrude honed? I had a set of SLP or something runners that were extrude honed. I wound up selling them before I got them on my car so I didnt know what kind of gains there were to be had.

I would get the mainifolds extrude honed in addition to grinding to match the exhaust ports and radius the turns like you are showing

 

It's a good idea, because there is no other way to polish the entire innards. But a better alternative is porting then ceramic-coating. Especially for turbo builds. If you get the iron too hot, it cracks. If you hone it too thin, it gets too hot, then cracks. Extrude-Hone can adjust the abrasive-ness and pressure to either just polish, or to really re-shape the restrictions. If there were no headers, I'd go for the reshaping, then try to ceramic-coat. IDK if the coating would stick after the honing.

 

My point was that from the factory, the truck manifolds that are commonly used in turbo applications are very good as they are. No additional rework is necessary for MOST applications. I mean you can get by using them as is, but certainly some porting to improve the flow will help and can be worth it for those looking to maximize efficiency from the design.

Now I'm not 100% positive that box stock truck manifolds made 1500 hp, I'm going by faint memory from what I remember hearing from my lsx turbo buddy and from a post I read awhile back on ls1tech. I remember hearing 7 second 1/4 mile times and thats up in the 1500hp range. They may have port matched it to the heads they used, I will have to look for it.
Maybe another 100 hp could have been found by porting and well worth the effort if it only does take about 2 hours to accomplish. Then again, I'd be more than happy with 1000hp and zero time spent grinding if I could get away with it. Flip side of the coin I guess. I personallly dont like grinding /porting.

Also realize that most people doing turbo builds for well over 1000whp fab up custom headers themselves and do not use any type of factory manifold or fabbed up log headers. They all use a type of header with collector, sometimes equal length tubes sometimes not but a 4 into 1 type merge collector is common. Is this better? Hard to say, I never seen good comparisons to determine what setup actually makes the most power and does it most efficiently. I'd love to see backpressure readings on same engine/turbo setups and same boost levels to then compare to the power they make.

I never ported anything Iron before, so I was expecting more time involved in the port job on those things to see worthwhile gains. If it does take a few hours per side and it doesnt take an experienced porter to do it to get gains, then ok I would go for it. Smoothing flow is always a good thing dont get me wrong, but i was simply pointing out that they are pretty darn good out the box.

I dont know how the other factory style manifolds are in comparison so that would be interesting to see, because the truck ones I dont think fit the Fbody cars.

For thirdgens, factory C4 vette manifolds seem to be a good option for a cheap cast manifold that may be used for a turbo setup. I'd be curious in a before / after port comparison on something like that.

 

7s? In the 1/8 mile, that's easy to believe.
It must be admitted that I am an accomplished grinder, so getting the above-pictured results in the time claimed is very real. And the pics above are the truck manifolds.
As for fitment, I will be trying that sometime this summer, in my own '84 Trans Am.
As for relevance, the red-highlighted parts of that first pic could perfectly well have come from the '00 Z28 LS1 exhaust manifolds I got from five7kid, and I will be porting those as well.
I do remember seeing some dyno results from a 2.3L Mustang SVO, comparing the stock exhaust manifold to a fabricated turbo header, with equal-length primaries. With no other changes, the results did improve. Details, well, I honestly can't remember any more than that.
Porting really isn't fun, but when you feel the results of good porting, in a car which has a combo that really was begging for it, well, there are plenty of good porting shops doing brisk business.
But the best of them, Total Engine Airflow, wanting $995 exchange to do a stage 1 on the #241 heads? I can do as well for about 1/4 of that cost. And $750 is pretty good motivation for anyone who's currently bringing home less than, say, $50,000 / year, after taxes. And I'm currently WAY below that, sadly enough.

 

yeah some costs for port jobs are up there, which makes you want to save money to just buy a set of heads or whatever.

After alittle more research I have found that Ohio Boys went 202 mph in the 1/4 on a truck manifold setup at 3600lb raceweight Thats over 1700whp they say (near 2000 at motor)

Kurt Urban performance went 7.60 at 190 with a truck manifold setup.

So they can perform well when done right. No idea if they are ported or not but I would think they have some tricks to them to work that well.

 

TEA's 241s are still cheaper than buying heads, even from Dart. And as much as AFR is known for good exhaust ports, TEA's 241s are better than AFR's 205 Mongoose heads.
For folks under 50k, buying heads is out, D-I-Y porting is in.

 

Any shots of the actual collector on these manifolds? I've never seen truck manifolds in person so I'm curious as to the size and shape of how the primary tubes come together.

 

Yeah, I can get pics in the morning. Right now it's 90 degrees and raining, so I'm staying here in front of the air conditioning.

 

Are the TEAs new castings or a set of stock castings that they have worked over? I know that Patriots seem to be the ones people are going after due to them being brand new castings that they take and CNC port the heads, valve grinds and polish for the same price of what their equivelant of the Stage 1 heads are on a set of 243 LS6/LS2 castings.

It seems that cast f-body manifolds are going up in price due to the fact they can be ported and alot of people are going to those over paying the outrageous price for headers for the 4th gens.

 

The TEA 5.3s are based on new castings, and far out-flow the Patriots.
Be aware that Patriot's porting group is a bunch of Ford 3-valve lovers, so they think it's funny to make GM guys think they have good heads. They want the Mustangs to beat the LSx guys.
In any case, what I'm working on will better the last Patriot results I saw.

 

 

That looks like my 99 TA manifolds except mine look stamped from steel.

Also pretty much resembles my turbo manifolds I made for my car.

 

Yeah, the '98-'99 models had actually Stainless manifolds on them, in '00 they went back to cast iron.

 

Couple of comments/questions, just for clarification:

If you don't port your heads, you don't want to open up the manifolds, correct? Or at least not the full rounding of the manifold (the smoothing would still improve flow), unless this follows the "header bigger than port" approach.

And, is there any gain in rounding the bottom? Even the L92 heads have "D" exhaust ports. As I understood it, the flat bottom port results in better overall flow properties since the gas flow coming off of the valve seat radius isn't going to conform to the round shape, anyway.

Don't take this as criticism, I'm just trying to get it straight in my head. If experience says otherwise, I'll be happy to relent, as I have none.

 

We're cool.
I like the full rounding for 2 reasons. In no particular order: (A) I like the anti-reversion effect, minor as it is. (B) While some turbo apps swap the manifolds side for side, others instead flip them upside down. Then the floor is the roof.

 

There is a lot of talk about shorty headers not showing gains over manifolds (which I'm not convinced is completely valid - I haven't seen any data on 1-3/4" primary shorties, for instance). If a member decided to keep their manifolds, especially the later "better" f-body pieces, what would you recommend?

 

Such a loaded question. First, I'm not convinced that the '01-'02 exhaust manifolds are any better than the '00, where's the evidence?
I like iron manifolds for the low initial cost, and the stealth factor. They can be Extrude-Honed, or coated, or maybe both, ans still be stealthy. Using them, you don't need an E.O. sticker. Ricers underestimate you, unless you are showing a power adder.
I see no worthwhile advantage to shorty headers when the manifolds are as good as these. For the LG4 and LO3, yes, but not here.
I like long-tubes for ALL V8s of American origin. Except Ford PowerJokes.
I doubt shorties would show any gains at all over well-ported manifolds. You're just mis-using your funds and tipping your hand, both needlessly.
That's IMHO, for what it's worth.

 

Good enough. Any comment I have from here on would be thread hijacking.

 

Were you going to protest the abrupt increase in the cross-sectional area?
And since you seem to have decided against them, I've started porting the '00 SS manifolds. I'm about 3/8 done with one of them already.

 

No. More unrelated chatter about getting shorties if one doesn't have manifolds.

I haven't decided against manifolds. I've been known to get past mental blocks before. And, I wasn't sure if you were discussing only truck manifolds in this thread (flipped for turbo), or LS1 manifolds as well. I hadn't put them side-by-side because I didn't have both at the same time, but from what I recall, they are very similar at the ports. About a year ago I was hoping truck manifolds would fit in a 3rd gen (NA) because at the time I had two LQ4's in the storage unit.

 

Getting the side-by-side pics I can do today. Showing how the truck manifolds fit in my '84 Trans Am, well, it'd be cheating since I'd be "mounting" the engine with 2x4" wood blocks. And neither of my LSx blocks is actually sitting in my T/A right now. My garage is full of my '83 C-10.
If you want manifolds, you can get virgin pieces from lots of sources. If you want ported, well, that part of the offer stands.

 

If I wasn't so lazy I would have pulled the headers off and tried the truck manifolds in the car. They appeared to kick out to far, though, and that's what I was told by TGO members.