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Flat Plane V8 Race Engine - Single Exit Exhaust Question

General engine tech -- Drag Racing to Circle Track

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RevTheory
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by RevTheory »

Hey Calvin, it's nice to see you lurking again.

Edit: You threw a boulder in my pool of tranquility on pairing up both banks using Pipemax lengths :lol:
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by englertracing »

exhausted wrote: Sun Dec 08, 2019 8:30 am
englertracing wrote: Sun Dec 08, 2019 6:28 am
exhausted wrote: Sat Dec 07, 2019 9:46 pm So this is a 250 inch V8, two banks and each bank header is using a 2.5" collector choke?
What is the port area? IMO you are way off somewhere. :shock:

If I read 400 hp than 2.5 OD is good enough for a tail pipe and you can always step up a bit with some AR valves.
There is no problem running any engine through a single tailpipe. You do have to get both banks exactly equal length into the final merge though, that is critical. Even two 2.5" tubes going into one 2.5" tailpipe would be fine as the 2.5 is way too big already... :D
So
1. Is 1.625 off the head too large if it matches the port?
1.1 Could necking down to 1.5 after the flange benefit this engine as its quite small.

2. What might be an appropriate choke size for the collector?
2.1 could probably be quite small on a flat plane right? Perhaps.
even as tight as 1.5x primary area?

For a 1.625" header that would be a 2" choke

3. What would be a good diameter for the secondaries? 2.250"?
3.1 Do you cone up to that? Or is it effective to use for example
a few inches of 2", then a few inches of 2.125, then the 2.250
3.2 would it be good to run some length of the choke diameter to an AR and out with the ideal secondary size

4. What size tailpipe?
4.1 any choke in the 2-1?
Well I've stuck my finger in a hornets nest... You should just call me. Please email or pm me and I would be happy to talk.
Calvin


Well it isn't mine, i was just pondering it..
You know for fun/refrence
Personally Im going to be sorting an exhaust for a 13,000 rpm 450cc twin next week in a PITA tight chassis for someone.

Perhaps the OP should contact you, but i would be curious to hear what the doctor perscribes.
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by exhausted »

Ok, I got ya. No problem. Sounds like a SB chevrolet maybe?
Anyway, Another story.

I once talked Ernie Elliott into shortening a oil pan so I could run two tubes under the engine. I built a 421 setup and ran the PS secondary under the pan and right into a 4into1 collector. The DS was sort of scrunched up and circled around to get those secondaries into the 4into1 collector on the DS.
Talk about screaming... This was for a plate motor back in the day. I was told it took off like a rocket but top speed wasn't any better. The sound was so bad they really didn't want to play with chokes or anything. It would drive you crazy and shatter tailpipes... :D

I would love to talk a GT-40 owner or anyone else with something like that into a 8-into-4-into-1 system instead of a 8-into-2 system. They are missing some torque.
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by oneaves2005 »

Thanks for everyone's input, will PM you Calvin
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by englertracing »

exhausted wrote: Sun Dec 08, 2019 9:05 pm Ok, I got ya. No problem. Sounds like a SB chevrolet maybe?
Anyway, Another story.

I once talked Ernie Elliott into shortening a oil pan so I could run two tubes under the engine. I built a 421 setup and ran the PS secondary under the pan and right into a 4into1 collector. The DS was sort of scrunched up and circled around to get those secondaries into the 4into1 collector on the DS.
Talk about screaming... This was for a plate motor back in the day. I was told it took off like a rocket but top speed wasn't any better. The sound was so bad they really didn't want to play with chokes or anything. It would drive you crazy and shatter tailpipes... :D
So it was a 8-4-1 exhaust?
It sounded bad like how?
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by exhausted »

englertracing wrote: Mon Dec 09, 2019 4:32 am
exhausted wrote: Sun Dec 08, 2019 9:05 pm Ok, I got ya. No problem. Sounds like a SB chevrolet maybe?
Anyway, Another story.

I once talked Ernie Elliott into shortening a oil pan so I could run two tubes under the engine. I built a 421 setup and ran the PS secondary under the pan and right into a 4into1 collector. The DS was sort of scrunched up and circled around to get those secondaries into the 4into1 collector on the DS.
Talk about screaming... This was for a plate motor back in the day. I was told it took off like a rocket but top speed wasn't any better. The sound was so bad they really didn't want to play with chokes or anything. It would drive you crazy and shatter tailpipes... :D
So it was a 8-4-1 exhaust?
It sounded bad like how?
Really high pitch, it is a true 90 degree but one pipe. Those boys were used to two pipes and unbalanced. Even the fans hated the V6 Busch cars...
Calvin Elston
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704-443-8088
Web: www.elstonheaders.com
Blog: www.exhausting101.com
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by oneaves2005 »

Hi All,

So I have purchased pipemax and inputted my specs. The specs come out with the following primary/collector dimensions - I am fairly happy with the recommended header dimensions at that is roughly what I expected, but the collector sizes seem a little on the large size to me. should I consider a tri-Y exhaust for my application??? Discuss.......

Exhaust Header Type = --- Primary Tube Specs : Race Header • Multiple Steps ---
--- 2-Step Primary Pipe Specs --- ( Total Length= 26.500 to 28.877 inches )
1st Step Diameter inches= 1.509 Length= 13.250 to 14.438 inches
2nd Step Diameter inches= 1.634 Length= 13.250 to 14.438 inches

--- 2-Step Primary Pipe Specs --- ( possibly higher RPM HP )
1st Step Diameter inches= 1.509 Length= 6.625 to 7.219 inches
2nd Step Diameter inches= 1.634 Length= 19.875 to 21.658 inches

--- 3-Step Primary Pipe Specs --- ( possibly higher RPM HP than 2-Step Headers )
1st Step Diameter inches= 1.509 Length= 13.250 to 14.438 inches
2nd Step Diameter inches= 1.634 Length= 6.625 to 7.219 inches
3rd Step Diameter inches= 1.759 Length= 6.625 to 7.219 inches

--- 3-Step Primary Pipe Specs --- ( possibly higher RPM HP than 2-Step Headers )
1st Step Diameter inches= 1.509 Length= 6.625 to 7.219 inches
2nd Step Diameter inches= 1.634 Length= 6.625 to 7.219 inches
3rd Step Diameter inches= 1.759 Length= 13.250 to 14.438 inches

--- 4-Step Primary Pipe Specs --- ( possibly higher RPM HP than 3-Step Headers )
1st Step Diameter inches= 1.509 Length= 6.625 to 7.219 inches
2nd Step Diameter inches= 1.634 Length= 6.625 to 7.219 inches
3rd Step Diameter inches= 1.759 Length= 6.625 to 7.219 inches
4th Step Diameter inches= 1.884 Length= 6.625 to 7.219 inches

--- Primary Tube Harmonics --- ( One-End-Closed Tube = Odd Numbered Harmonics )
1st Harmonic = 85.099 to 87.476 inches long ... typically never used ( too long to fit any Vehicle )
3rd Harmonic = 26.500 to 28.877 inches long ... highly recommended , best Torque and HP Curve
5th Harmonic = 14.780 to 17.157 inches long ... shortest recommended ( Shorty or very Hi-RPM Header )
7th Harmonic = 9.757 to 12.134 inches long ... shortest recommended ( Shorty, Hugger, or Log Style )
9th Harmonic = 6.967 to 9.344 inches long ... shortest recommended ( Log Style or Cast-Manifold )
11th Harmonic = 5.191 to 7.568 inches long ... shortest recommended ( Log Style or Cast-Manifold )

--- Collector Specs : Straight Tube Collector • or Straight with a more Merge shape ---
Peak TQ Diameter Range = 2.775 -to- 2.900 Best Length= 18.468 -or- 36.936 inches
Best Mid-Range Diameter = 2.900 Best Length= 18.468 -or- 36.936 inches
Peak HP Diameter Range = 2.900 -to- 3.025 Best Length= 18.468 -or- 9.234 inches

H-Pipe Location= 18.468 or 9.234 inches X-Pipe Location= 73.873 or 36.936 inches
( both H-Pipe and X-Pipe locations are measured from Primary Tube ends inside the Collector )

Dual-Exhaust System Diameter = 2.775 to 3.025 inches Dual-Exhaust's each Muffler CFM = 453
Single-Exhaust System Diameter = 3.896 to 4.021 inches Single-Exhaust's one Muffler CFM = 905

--- Collector's Harmonics --- ( Both-Ends-Open Tube = Odd and Even Numbered Harmonics )
1st Harmonic = 147.746 inches long ... longest recommended with Mufflers and TailPipes
2nd Harmonic = 73.873 inches long ... longest recommended with Mufflers and TailPipes
3rd Harmonic = 36.936 inches long ... greater Low RPM Torque -to- Peak Torque RPM
4th Harmonic = 18.468 inches long ... highly recommended , best Torque and HP Curve combination
5th Harmonic = 9.234 inches long ... reduced Peak Torque , higher RPM HP gains possible
6th Harmonic = 4.617 inches long ... reduced Low RPM Torque , even though Tuned Length
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by Juho_ »

I found the same thing (collector diameters)
Just got the new version of pipemax.

A lot different compared to 3.98.

Any thoughts?

I'll do some more testing later with more time on the new pipemax and see if I've just had inaccurate value(s).
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by englertracing »

If there is no option for flat plane in pipe max it is likely giving you 90* collector specs.
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by oneaves2005 »

Good point, will try running as a 4cylinder to see what that gives
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by exhausted »

oneaves2005 wrote: Wed Dec 11, 2019 3:25 pm Good point, will try running as a 4cylinder to see what that gives
Or a 3 cylinder...
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by exhausted »

Self GM ecotech 6 banger. Didn't go to final collector, didn't need the bottom end...
1.75@6", big step to 2.12and then to 2.25 @ 20"?
2.5" chokes
Self Racing 6 CYL 07-2008 007.jpg
Self Racing 6 CYL 07-2008 006.jpg
Self Racing 6 CYL 07-2008 002.jpg
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by exhausted »

KEA factory 4 cylinder road racing.
12-13"" primaries and the secondaries were over 24", hello?
:D
Kin-Sunbelt KIA (16).JPG
Kin-Sunbelt KIA (15).JPG
Kin-Sunbelt KIA (14).JPG
Kin-Sunbelt KIA (13).JPG
feb92007 002.jpg
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by exhausted »

Nahan Cleveland head comp.
This was before I learned that the primaries need to be short...
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188200212@23 (2).jpg
188200212@23 (1).jpg
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Re: Flat Plane V8 Race Engine - Single Exit Exhaust Question

Post by hoffman900 »

Calvin,

That Kia header seems to be a 180* on the Burns style of designing Tri-ys, which seems to result in half length secondaries (as compared to the primaries). Thoughts on why to do it that way?
-Bob
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