tri-y headers and smaller exhaust system

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Re: tri-y headers and smaller exhaust system

Post by 77cruiser » Mon Apr 15, 2019 10:37 pm

Gaskets for track 1 heads by Felpro are close & the holes need to be slotted on them. I put mine back on with Hi Temp RTV.
These.
https://www.summitracing.com/parts/fel- ... /chevrolet
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Re: tri-y headers and smaller exhaust system

Post by steve cowan » Tue Apr 16, 2019 3:51 am

i scraped the flange plate idea.
i cut some 1'' x 1'' x 5/16'' flat plate and welded into floor of header,i have left the square edge into the pipe as a AR ?? comments
these headers seem to be centered in the middle of the port height wise,i slotted holes so roof and sides line up pretty close.
the photos are not pretty but i think it will work,the Dart 178 cc i have on the moment is a 1444 felpro opening size as standard 1.38'' x 1.38''.
i will need to fabricate a new gearbox cross member as well,i want to keep the collectors running true and straight.
i have done 2 flat plates only 6 to go. :D
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Re: tri-y headers and smaller exhaust system

Post by cjperformance » Tue Apr 16, 2019 4:07 am

The look does not matter , no one will see it ! :lol:
The 'AR' square edge may or may not help,, hows that for a decisive answer?!,, in any case it definitely wont hurt at cruise/lighter throttle loads, most likely wont hurt mid range/tq. Only testing will prove it for your combo , maybe just moving that mismatch down stream that little bit will help it everywhere.
Good work.
Craig.

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Re: tri-y headers and smaller exhaust system

Post by steve cowan » Tue Apr 16, 2019 4:30 am

:D
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Re: tri-y headers and smaller exhaust system

Post by steve cowan » Thu Apr 18, 2019 7:42 pm

tri-y 001.JPG
updates-
finished welding in all plates and hand finished one side.
i am unable to use the flowmaster merge pipes (bummer) the inlet angles are spread to wide.i cut one of my secondary pipes to try and compensate for better transition but makes the pipes to wide and fouls on the starter,front end.
my options were slim so i did the best i could into the merge area.
i welded in some AFR bungs at the merge - the sensors are facing up in the 11 oclock position.
collector length ???
i have slip on extensions i can add later
i am looking for a starting point 15'' ?? maybe having slightly shorter.
if these pipes show potential i would consider getting a copied set made in stainless with corrected CSA at the flanges and merge areas.
comments appreciated.
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Re: tri-y headers and smaller exhaust system

Post by cjperformance » Thu Apr 18, 2019 8:17 pm

Steve, if you want a very easy , quick and cost effective way to play with collector length just cut what you have back to say 6" - 9"
Make up several collectors in different lengths and have an exhaust shop pump out one end to slip over your short collectors.
You can then 'slice and clamp' the slip join or 'hook and spring' the slip joint into place.
This makes a collector length swap a 5 minute job.
Good work.
Craig.

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Re: tri-y headers and smaller exhaust system

Post by steve cowan » Thu Apr 18, 2019 9:58 pm

cjperformance wrote:
Thu Apr 18, 2019 8:17 pm
Steve, if you want a very easy , quick and cost effective way to play with collector length just cut what you have back to say 6" - 9"
Make up several collectors in different lengths and have an exhaust shop pump out one end to slip over your short collectors.
You can then 'slice and clamp' the slip join or 'hook and spring' the slip joint into place.
This makes a collector length swap a 5 minute job.
Good work.
thanks Craig,
if i cut the collector back to 9'',what would you recommend as a good extension length 6''-8''-10 ? 6''-10''-14''
probably answering my own question here lol- have as many different lengths as possible and test them all :D
i have a local guy who is helpful - exhaust shop
i figure test with short and then change to a long extension and see the differences,
what does make me leery on this is because i am track testing only -there are so many variables - i have to be careful i dont chase my tail on collector extension tuning for 6 months :lol:
appreciate your help mate.
steve c

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Re: tri-y headers and smaller exhaust system

Post by MadBill » Thu Apr 18, 2019 10:16 pm

You're not limited to a single extension; with the right lengths, you can easily stack up several as required to get virtually any length +/- 1".
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Re: tri-y headers and smaller exhaust system

Post by cjperformance » Fri Apr 19, 2019 2:04 am

Good point Bill ! That cuts down on the ammount of test pieces you need.
Yes Steve you could endlessly play with collectors. Dont go nuts. Just cut yours at lets say 6". Take a 12 , 6 and 3" extension with you. Or pipemax some collector options as some baselines, your pipes wont match exactly what pipemax says but you'll be close enough to experiment.
If the car is consistent already just do a quick and dirty test,, 1 clean run on each length. Pick the best looking mix of 60'(indication of TQ/response) & e/t (indication of average mph/hp) then tune for the best on that collector. Then try the lengths again maybe just to 're average' it. You will see a trend quickly. Basically after 5 or 6 clean runs you will have a pretty good idea what the car and pipe combo likes. Then do a few runs and usual tune checks etc to test consistency. Its hard sometimes when you dont get many in a given meeting. Or find a nice backroad and have some fun!!
Craig.

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Re: tri-y headers and smaller exhaust system

Post by steve cowan » Sat Apr 20, 2019 7:09 pm

bill and Craig,
thanks for your comments always appreciated,in the process of doing a gearbox cross member at the moment,pipes are done.
i have a Nostalgia meeting today week that i have entered.i will get three qualifying runs and then 3 x eliminations (Chicago shootout deal)
i want to run with full exhaust system for that meeting to get a sort of baseline to work off.i hope my carb tune does not go down the toilet with the header and exhaust change,i just hope the mph shows a decent change (positive or negative)
i dont want the changes coming from just different weather conditions.
there are so many variables but thats the position i am in and i just have to accept it for what it is.
will keep you posted with results :D
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Re: tri-y headers and smaller exhaust system

Post by KnightEngines » Wed Apr 24, 2019 10:04 am

More fuel to the fire, did some testing today with a couple of sets of tri y pipes & left with results contrary to what everyone in the room was betting on, including me.

Motor was a 383 Holden street & occasional strip.
Pump fuel (our 98, equivalent to US 93), solid flat cam, 268/272 on 109 centres, in on 105icl, lift around .630/.610 with 1.65 rockers.
12:1 comp, 850 carb.
This motor wore alloy heads rather than the ported iron I favour for this sort of build, roughly 300/208cfm at lift used & a chamber I did not like (soft & shallow).
Made 500lb @ 6100, 570hp @ 6300 as a baseline.
Baseline headers were 1.75/2/2.5 choke, 3" collector tri y.
Then we tried 1.75/2.25/2.5 choke, 3" collector - much nicer choke & collector.
It lost power bad, 10lb & 10hp before 5500rpm & dropping hard with rpm, aborted run at 5500, it was nose diving & down from the hit at 4500.
Faffed around for 2x more aborted runs & only dropped more power.
Put the crappy looking pipes back on and it mirrored the last run with them.
So it didn't like more header, which begged the question is it over exhausting?
So, despite the consensus in the room saying it was a waste of time I took exhaust lash from .018 to .024".
It picked up from the hit too 1000rpm past peak, 7lb & 5hp.
We finished up at 507lb at 5100, 575hp at 6300, holding 560hp to 7100.

I was right to dislike the chambers, it was timing insensitive, 28/30/32 deg, very little change - a good chamber will see significant loss 2 deg either side of the sweet spot, this did not.

If I was to grind another cam for it I'd take out 4 deg ex duration & .020" of lift, bump compression to 12.3 or so & I think it could make 590hp.

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Re: tri-y headers and smaller exhaust system

Post by CGT » Wed Apr 24, 2019 12:28 pm

KnightEngines wrote:
Wed Apr 24, 2019 10:04 am
So, despite the consensus in the room saying it was a waste of time I took exhaust lash from .018 to .024".
Or did it just like the exhaust valve coming off the seat a little faster?....depending on lash ramp.
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Re: tri-y headers and smaller exhaust system

Post by tenxal » Wed Apr 24, 2019 5:13 pm

KnightEngines wrote:
Wed Apr 24, 2019 10:04 am
If I was to grind another cam for it I'd take out 4 deg ex duration & .020" of lift, bump compression to 12.3 or so & I think it could make 590hp.
You also found out something about the lobe separation angle.

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Re: tri-y headers and smaller exhaust system

Post by Rick360 » Wed Apr 24, 2019 6:11 pm

KnightEngines wrote:
Wed Apr 24, 2019 10:04 am
More fuel to the fire, did some testing today with a couple of sets of tri y pipes & left with results contrary to what everyone in the room was betting on, including me.

Motor was a 383 Holden street & occasional strip.
Pump fuel (our 98, equivalent to US 93), solid flat cam, 268/272 on 109 centres, in on 105icl, lift around .630/.610 with 1.65 rockers.
12:1 comp, 850 carb.
This motor wore alloy heads rather than the ported iron I favour for this sort of build, roughly 300/208cfm at lift used & a chamber I did not like (soft & shallow).
Made 500lb @ 6100, 570hp @ 6300 as a baseline.
Baseline headers were 1.75/2/2.5 choke, 3" collector tri y.
Then we tried 1.75/2.25/2.5 choke, 3" collector - much nicer choke & collector.
It lost power bad, 10lb & 10hp before 5500rpm & dropping hard with rpm, aborted run at 5500, it was nose diving & down from the hit at 4500.
Faffed around for 2x more aborted runs & only dropped more power.
Put the crappy looking pipes back on and it mirrored the last run with them.
So it didn't like more header, which begged the question is it over exhausting?
So, despite the consensus in the room saying it was a waste of time I took exhaust lash from .018 to .024".
It picked up from the hit too 1000rpm past peak, 7lb & 5hp.
We finished up at 507lb at 5100, 575hp at 6300, holding 560hp to 7100.

I was right to dislike the chambers, it was timing insensitive, 28/30/32 deg, very little change - a good chamber will see significant loss 2 deg either side of the sweet spot, this did not.

If I was to grind another cam for it I'd take out 4 deg ex duration & .020" of lift, bump compression to 12.3 or so & I think it could make 590hp.
What did the O2 readings do with the 2nd set of headers? I've seen exhaust have a significant effect on O2 and sometimes have an initial HP/TQ loss and need re-jetted, ending up with more power after the re-jet.

Headers, collectors and/or exhaust system seem to affect the mixture that ends up in the cylinder after the valves are closed.

Rick

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Re: tri-y headers and smaller exhaust system

Post by KnightEngines » Wed Apr 24, 2019 7:35 pm

Lambda went lean with the bigger pipes, jetted up & lost more power, straight away it was clear the pipes did not suit the combo.
1st time I've used these particular heads, looks like slightly wider lobe sep, a bit less exhaust lift & a bit more compression would be closer to optimal for them.

Would have been nice to have more time to play, even with the smaller pipes it made best power at .90-.91 lambda, leaner than usual, vac under carb was just touching 1" at 6500rpm, but carb signal was still good, 72/76 jets with front power valve & still looking a little rich on the plugs, but didn't dare run leaner!

We hit our power & tq goals with change, but it's clear there is more there to be had with r&d. When things don't go 100% your way is when you learn stuff!

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