Are Longtubes bad for DOHC engines?

[KBR]

Ummmmm, might have been the 4# of additional boost...

Out of curiosity what size upper?

3.0 upper...I should have added that I was at 16.8 lbs before 4lb lower and LT headers

 

[Black02GT]

3.0 upper...I should have added that I was at 16.8 lbs before 4lb lower and LT headers

Cool, that seems to be the sweet spot for the TVS before really over spinning it. I have to pick up a 3.0. I have the 4# lower laying around just kills me dropping $100 for the upper ring which feels like a $20 part.

Anyway, your car looks and performs great man.

 

[GodStang]

Correct and that’s why the gains are from pulleying it back. Run 18psi then add LTs and what not it drops the boost to ~16-16.5psi and then you Pulley it back to ~18psi. No it’s not massive gains but still are gains.

So, the amount of power an engine makes is purely a function of how much air flows through it. Thing is, a PD blower is Positive Displacement - once the throttle is wide open, every rotation of the compressor moves the same amount of air. The only way to change how much air it moves is to change the pulley. That means that adding higher flow manifolds or LT headers won't have a material impact on power because the blower keeps pushing the same amount of air.

What these parts might affect is back-pressure - the thing we all know as "boost". The better the engine flows air, the lower the back-pressure, the cooler it runs. "Boost" goes down, power stays the same, engine runs cooler. So, unless your engine has serious problems, all LT's might give you is lower back-pressure and substantially the same power. If back-pressure isn't lower, then you wasted your money on headers because the manifold you had before wasn't blocking exhaust flow.

 

[Bdubbs]

I dropped about 1 psi of boost adding ARH headers. Would I do it all over again? Probably not, but the sound is nothing short of awesome.

I have a lot of money stuck into them for minimal hp gains.

I'd like to think now that I'm spinning the blower up to 21 psi and E85 compared to the previous 17 psi and 91 fuel they are helping out. But I have zero data to back that up.

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[Nervouswreck]

Ummmmm, might have been the 4# of additional boost...

Out of curiosity what size upper?

2.7


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[BOOGIE MAN]

The sound alone is worth every penny

Posts are mine and do not represent my employer. Actually, my posts are riddled with humor and sarcasm and are not to be taken as a representation of my thoughts, feelings, or ideas. Same goes for my "likes"

 

[Albatross]

The sound alone is worth every penny

^^Agreed!

 

[SVTdreamin04]

I pulled my motor from the top with the macs and it wasn’t too bad. Put the new motor in with the kooks and it was a little tougher. Kooks are a tad longer than the macs.

Pulling wasn’t as bad as putting it back in with the headers. I don’t know if the tubular k member made it harder or easier. The k member was in the car when I pulled the engine as well.


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[c6zhombre]

View attachment 1643903



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Bwahaha

 

[c6zhombre]

Aren't the 700's on corn with a 2.3 VMP or Whiple the norm these days? I know Timspony did, possibly BDubs. I'm thinking I'll hit over 750 with a lower making 725 with only a 2.8 upper, stock lower. Switch to a 3.0/4# steup don't think 25hp with an extra 2-3psi isn't out an out of this world expectation. Also cheating though (flat tops).

For sure there are many. I only mentioned it because there are several new members that might not be aware of the potential that can be reached on a 2.3 + E85. On a totally factory 03/04 motor.

 

[Black02GT]

For sure there are many. I only mentioned it because there are several new members that might not be aware of the potential that can be reached on a 2.3 + E85. On a totally factory 03/04 motor.

Indeed, the corn really raised the bar.

 

[SVTdreamin04]

Indeed, the corn really raised the bar.

It woke my car up.


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[04screamingvert]

I finally scored a set of MAC Longtubes for my Cobra and after doing some research on Stangnet and Some other places , and I’m reading some people are saying that Longtubes “suck the valve seals out” and are bad for our motors ????? Has anyone else heard this ????


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Never heard that one sucking the valve seals out that’s a new one for me. I’ve had Kooks headers and an off-road X pipe on my 04 cobra for a number of years. I saw a 30 hp increase and 71 foot pound increase at the wheels and I really like the sound of it through my SLP2. I think Kenny Bell has really good article on header size And benefits on their website.