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Old 06-10-2019, 07:00 AM
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Exhaust port shape

So I’m building a 383 for an s10 and have already purchased the patriot conversion headers since they ease the installation without any grinding. Well my heads have a square exhaust port and my headers are round. What can I do about this? Do I just need to find a pair that’s square as well? Or since it’s a performance street engine would the two different ports even matter that much ? The power should be roughly around 500/500 hp/tq. 1500rpm to 6000rpm.

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Old 06-10-2019, 08:42 AM
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A real 500hp on a 383 is pretty stout. So much I have some doubts. Especially on those heads.
Any way, you're not hurting it enough to matter but a square flange header would be ideal.
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Old 06-10-2019, 08:43 AM
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A real 500hp on a 383 is pretty stout. So much I have some doubts. Especially on those heads.
Any way, you're not hurting it enough to matter but a square flange header would be ideal.
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Old 06-10-2019, 09:05 AM
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Quote:
Originally Posted by Cameronluster View Post
So Im building a 383 for an s10 and have already purchased the patriot conversion headers since they ease the installation without any grinding. Well my heads have a square exhaust port and my headers are round. What can I do about this? Do I just need to find a pair thats square as well? Or since its a performance street engine would the two different ports even matter that much ? The power should be roughly around 500/500 hp/tq. 1500rpm to 6000rpm.
The headers should match the port, the one thing that cannot stand is header flange that hangs into the port. If they clear the port all the way around for each tube the shape of the header side doesn't matter. But if they obstruct the port of the head engine power is just absorbed right there.

500 pound feet and 500 hp is a lot of power out of a 383 taking a lot of cam, compression, forged internals, and a lot of machine and assembly care.

Bogie
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Old 06-10-2019, 09:58 AM
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You should be satisfied with a 383 CI engine with 400 HP at the flywheel measured with a butt-dyno at 4,000 RPM. That will need 12:1 CR and 100% VP 108 octane racing fuel.
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Old 06-10-2019, 11:34 AM
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Originally Posted by MouseFink View Post
You should be satisfied with a 383 CI engine with 400 HP at the flywheel measured with a butt-dyno at 4,000 RPM. That will need 12:1 CR and 100% VP 108 octane racing fuel.
This is a true statement it is a rather ridiculous premise.....400 Hp @ 4000 rpm does require that high compression figure because you need to be making 520 Ft.lbs torque @ 4000 rom to get that HP.....but if you just push that to the same 400 HP just 500 rpm higher @ 4500 rpm you only need 466 ft.lbs to get there.....easily doable on pump gas.

The figures 400 HP/466Ft.lbs Torque @4500 rpm is characteristic of a 500 HP peak 480FT.Lbs torque peak engine.....and that can be done with 385 cubes on pump gas, quite easily with off the shelf parts.

Just trying to say you need 400 Hp at exactly 4000 rpm is what makes the high compression a requirement....that's a very low RPM to expect to get 400 HP unless it is a much bigger engine than 385 cubes.....a 496 BBC would have no problem getting 400 HP at this low 3000 RPM point, on pump gas.

Talking about HP below the engine torque peak is a meaningless conversation anyway....torque is what should be the focus.....HP doesn't become the prime focus until you get above peak torque rpm.
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Old 06-10-2019, 11:57 AM
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Cameronluster...I take it since you are using the 200cc Edelbrock head and having a header port smaller than the port opening that you are using the 1-1/2" primary/2-1/2" collector Patriot "Clipster" header??

You won't get anywhere near 500 Hp with that small a header pipe. 430 HP is going to be a miracle.

Those are a "convenience header", made for under 350 HP applications for ease of fit.....not made for a build shooting for near 500HP and TQ.
It's more of a stock 305/350" 300 Hp header than it is anything else.

If you are serious about those power numbers you want to hit, you need at minimum Hedman #69490, full length 1-5/8" primary headers. This will get you to right close to 500HP before they startr to become a restriction.

If you are REALLY serious about actually getting 500+HP, then you need to be looking at Hedman #65853 1-3/4" full length fenderwell exit headers, as that is about the only thing big enough that isn't a custom built header.
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Old 06-10-2019, 02:58 PM
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Quote:
Originally Posted by ericnova72 View Post
Cameronluster...I take it since you are using the 200cc Edelbrock head and having a header port smaller than the port opening that you are using the 1-1/2" primary/2-1/2" collector Patriot "Clipster" header??

You won't get anywhere near 500 Hp with that small a header pipe. 430 HP is going to be a miracle.

Those are a "convenience header", made for under 350 HP applications for ease of fit.....not made for a build shooting for near 500HP and TQ.
It's more of a stock 305/350" 300 Hp header than it is anything else.

If you are serious about those power numbers you want to hit, you need at minimum Hedman #69490, full length 1-5/8" primary headers. This will get you to right close to 500HP before they startr to become a restriction.

If you are REALLY serious about actually getting 500+HP, then you need to be looking at Hedman #65853 1-3/4" full length fenderwell exit headers, as that is about the only thing big enough that isn't a custom built header.
Yes that’s exactly what I was thinking. I purchased the heads like over a year ago when I was shopping for everything. They have just sat in a box wrapped up till last night when I finally decided to get them out and check them out. I deff got them because of the ease of installation. Since I’ve used them before. I will most definitely go with something else now. There was a loud cuss word yelled when I noticed the shape. Yeah I’ll just have to do some modification to get some headman’s To fit. It’ll sound better saying I have those on my engine anyway.
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Old 06-10-2019, 06:44 PM
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Quote:
Originally Posted by Cameronluster View Post
Yes that’s exactly what I was thinking. I purchased the heads like over a year ago when I was shopping for everything. They have just sat in a box wrapped up till last night when I finally decided to get them out and check them out. I deff got them because of the ease of installation. Since I’ve used them before. I will most definitely go with something else now. There was a loud cuss word yelled when I noticed the shape. Yeah I’ll just have to do some modification to get some headman’s To fit. It’ll sound better saying I have those on my engine anyway.
Space the final frontier! While the universe has plenty and then some, S10 engne rooms don't.

Bogie
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Old 06-10-2019, 06:57 PM
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Quote:
Originally Posted by BogiesAnnex1 View Post
Quote:
Originally Posted by Cameronluster View Post
Yes that’s exactly what I was thinking. I purchased the heads like over a year ago when I was shopping for everything. They have just sat in a box wrapped up till last night when I finally decided to get them out and check them out. I deff got them because of the ease of installation. Since I’ve used them before. I will most definitely go with something else now. There was a loud cuss word yelled when I noticed the shape. Yeah I’ll just have to do some modification to get some headman’s To fit. It’ll sound better saying I have those on my engine anyway.
Space the final frontier! While the universe has plenty and then some, S10 engne rooms don't.

Bogie
can’t you do some modifications in a few areas in the engine bay to get other headers to fit?
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Old 06-10-2019, 10:12 PM
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Originally Posted by Cameronluster View Post
cant you do some modifications in a few areas in the engine bay to get other headers to fit?
For the street or strickly track?

For the street you're more likely to retain the inner fenders which eat a lot of space. Wheelwell exits have been tried but tire clearance is an issue approaching full lock, so you can go that route but you have to give up some turning radius which isn't all that great in these to start with. The drivers side you can open up some space if you reroute the brake lines and electrical wiring that go on to under that side of the firewall and forward floor pan. The passenger side is harder because of the starter even Sanderson inch and a half tube shorties are hard pressed to fit even with a mini starter. The forward floor and lower firewall on that side requires considerable modification, on my personal one which was the first one I built, I cut a section of floor out replacing it with a hammer to shape and beat to fit panel. This is to get the engine as far aft as possible for weight transfer and handling so there is a need to move the engine back about an inch and a half to two inches. I also run a small cap distributor on these swaps, you need to plumb for the back of the block oil pressue tap before installation it is nearly impossible to work on that once the engine is in. It's so tight in there that even mine with the battery in the bed, no AC, no power steering that when the fans are running at vehicle stand still air blows out of the engine compartment around the headlight bezels. A rear facing hood scoop would help vent the engine compartment and if you're race only removal of the inner fenders would provide more room for headers and venting. Mine is a daily driver in the coastal northwest where rain and snow are the overriding considerations requiring the engine stay dry on the top end and I wanted it to be a sleeper so no untoward modifications to the body profile was a rule.

Bogie
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Old 06-11-2019, 03:02 AM
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Originally Posted by ericnova72 View Post
Cameronluster...I take it since you are using the 200cc Edelbrock head and having a header port smaller than the port opening that you are using the 1-1/2" primary/2-1/2" collector Patriot "Clipster" header??

You won't get anywhere near 500 Hp with that small a header pipe. 430 HP is going to be a miracle.

Those are a "convenience header", made for under 350 HP applications for ease of fit.....not made for a build shooting for near 500HP and TQ.
It's more of a stock 305/350" 300 Hp header than it is anything else.

If you are serious about those power numbers you want to hit, you need at minimum Hedman #69490, full length 1-5/8" primary headers. This will get you to right close to 500HP before they startr to become a restriction.

If you are REALLY serious about actually getting 500+HP, then you need to be looking at Hedman #65853 1-3/4" full length fenderwell exit headers, as that is about the only thing big enough that isn't a custom built header.
here is a picture of the headers you suggested and in the same picture is another set that seems like it would work for me. What do you think? Also if I’m looking at it right the ones you suggested seem to also have a round port unlike the square/oval port my heads have. That could be a stock photo and not the the same exact i would receive but it doesn’t state anything is the details. (Not that summit is riddle with errors anyway ya know)
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Old 06-11-2019, 11:52 AM
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If you can't do the long tube or fenderwell headers, that 1-3/4" shorty is at least better than your 1-1/2" you've got now.

Hedmans web site search sucks, I didn't find the 1-3/4" shorty like that when I searched.
You don't have to match the square port opening in the head, most headers rarely do, ...you just want the round or oval tube opening big enough to not overhang and block some of the opening out of the head. 1-5/8" usually will on most any SBC 23 head, 1-3/4" definitely will clear even on the biggest 23 head..
If you look at that #69560 shorty at Hedmans site, it is a rectangular port opening.
https://www.hedman.com/product-detail/69560

You can make that 1-3/4 shorty better if you add about 16-18" of 3" collector length to it before necking down to 2-1/2" if you are going to use a smaller exhaust that 3" all the way out. Look for a mandrel bent large truck/school bus 3" x 45 bend, it'll be about right for making an extension.

The shorty will hurt some low end torque(that is where the long tube is better) because of the short primaries. That might nelp you depending on what size tire you have....help keep from just blowing them off all the time.
If you were going to race it, the fenderwells would be the only choice.

I'm really surprised no one else has much in the way of long tube choices for this swap, it is about the most popular swap of all out there.
I don't know why someone doesn't take that 1-3/4 shorty design, and instead of putting the collector flange here they do continue all four pipes tight together down at that same angle for 12" or so with abend at the bottom to get them level and then put the collector on it? If Hedman just made #69030 in 1-3/4" tube it would be perfect.
https://www.hedman.com/product-detail/69030
Similar to how these are grouped(I know these won't fit, just an example of tube routed together:
https://www.ebay.com/itm/EXHAUST-MAN...AAAOSwAutc~p8w

There are a ton of stainless shorty's on Ebay, you might search "SBC stainless headers" there and compare tube routing and location to those 1-3/4 Hedman shorty's....you may find a match for 1/3 of Hedman price, and their STAINLESS. There is only about 5-6 different tube routes to those shorty's, and everyone is copying everybody else on most of them.

I've bought a couple of the long tube sets from Ebay….quality is really very good, arguably better than most American header companies. Good thick 9 or 10mm flange and TIG welds.

Last edited by ericnova72; 06-11-2019 at 12:02 PM.
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Old 06-11-2019, 05:59 PM
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Originally Posted by ericnova72 View Post
If you can't do the long tube or fenderwell headers, that 1-3/4" shorty is at least better than your 1-1/2" you've got now.

Hedmans web site search sucks, I didn't find the 1-3/4" shorty like that when I searched.
You don't have to match the square port opening in the head, most headers rarely do, ...you just want the round or oval tube opening big enough to not overhang and block some of the opening out of the head. 1-5/8" usually will on most any SBC 23 head, 1-3/4" definitely will clear even on the biggest 23 head..
If you look at that #69560 shorty at Hedmans site, it is a rectangular port opening.
https://www.hedman.com/product-detail/69560

You can make that 1-3/4 shorty better if you add about 16-18" of 3" collector length to it before necking down to 2-1/2" if you are going to use a smaller exhaust that 3" all the way out. Look for a mandrel bent large truck/school bus 3" x 45 bend, it'll be about right for making an extension.

The shorty will hurt some low end torque(that is where the long tube is better) because of the short primaries. That might nelp you depending on what size tire you have....help keep from just blowing them off all the time.
If you were going to race it, the fenderwells would be the only choice.

I'm really surprised no one else has much in the way of long tube choices for this swap, it is about the most popular swap of all out there.
I don't know why someone doesn't take that 1-3/4 shorty design, and instead of putting the collector flange here they do continue all four pipes tight together down at that same angle for 12" or so with abend at the bottom to get them level and then put the collector on it? If Hedman just made #69030 in 1-3/4" tube it would be perfect.
https://www.hedman.com/product-detail/69030
Similar to how these are grouped(I know these won't fit, just an example of tube routed together:
https://www.ebay.com/itm/EXHAUST-MAN...AAAOSwAutc~p8w

There are a ton of stainless shorty's on Ebay, you might search "SBC stainless headers" there and compare tube routing and location to those 1-3/4 Hedman shorty's....you may find a match for 1/3 of Hedman price, and their STAINLESS. There is only about 5-6 different tube routes to those shorty's, and everyone is copying everybody else on most of them.

I've bought a couple of the long tube sets from Ebay….quality is really very good, arguably better than most American header companies. Good thick 9 or 10mm flange and TIG welds.
So The 69490 Headers. Do you think I will be able to squeeze them in my engine bay since they are longer? The main reason I used the shortys are because they just clear so much easier. But if I can make the long ones fit I’ll use them since the primaries are the perfect size for my heads. Im not going to race it. If anything I may run it for fun but it’ll mostly be for street use and whatever fun I can I can have in a parking lot. So I deff don’t want to use the fender well headers. I kinda want an in between I guess you can say. Like I can drive it when I want and if I ever want to run it I can do that to and have enough power to have some fun.
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Old 06-11-2019, 09:02 PM
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The #69490 is listed as a S-10 SBC swap header, so I don't know why it wouldn't fit??

My Dad had a 327 powered S-10 about 15 years ago that had a very similar header, but since he bought it already done I don't have any idea what brand the headers were. IIRC one tube on each side was separate and was a slip fit into the collector, it went out over the frame rail into the wheel well and then under the rail back inboard to go to the collector. Builder had to put a hole in the inner wheel wells at their back corner of the engine bay for that pipe to go through. I have never seen another pair like it except on a couple other S-10 swaps at car shows.

There are also Hooker #2837HKR 1-5/8 long tube Super Competition header, after looking at the catalog pics I think that is what my Dad's truck had, that driver side rear tube being slip fit and looks like it will go out over the frame rail.
If it is they fit really well, but needed shorty Accel sparkplugs in one cylinder with stock heads on it.
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