Are Longtubes bad for DOHC engines?

Hef

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Damn, that hp with a 2.3? You on the corn?
I'm at 714/680 with factory manifolds so I've been very impressed with how well the factory piece performs. I have had people guesstimate I'd pick up "30-40hp" by adding LTs.....so that would be possibly 754/720 with a 22psi gen 2 2.3 whipple.....I laughed. No way.

I have no doubt the sound change would be awesome tho.

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c6zhombre

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I am just a NA 99 cobra guy...but it seems to me that the only way to really measure the gain from LTs is to get the psi up to where it was before the LTs were installed, then compare RWHP gain....?

That's the true way to compare.....unless you are already at the max operating rpm the blower can spin. Pretty much where I'm at. I'm already spinning this blower max (I think). I guess if I added long tubes I could try a 2lb lower....but I'm probably already pressing my luck with current blower rpm.

If I added long tubes......I'd be adding a new gen4 2.9 or gen5 3.0 as well. And then head studs. Built T56. Solid rear. Holycrap.....ya, I'm not going down that rabbit hole lol. I'm pleased as is.
 

stangfreak

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I remember the legend of the Mac "engine destroyer" longtubes from way back in the day, but I know people run them on the 03/04's with no issues. The stock manifolds aren't as restrictive as most will say. Longtubes are only good for about 10 rwhp on these cars even into the 700 rear wheel range. If you like the sound that much go for it. Not worth the hassles they present IMO.

you are just looking at hp numbers. That magical screen that people obsess over. The stock manifolds are good. On certain setups. Once you start going with a big blower, built motor, the long tubes will help. Long tubes dissipate heat much better than the stock manifolds. Now add more boost, everything gets hotter. Its a more efficient setup. And, you were around since late 02 into 03, jimmy vaccaro, the god father of mustangs we call used to call him, did long tubes on his ported eaton. He wasn't concerened on the HP numbers. BC he knew on the eaton, nothing would be gained. when he did the long tubes, the same month, he brought the car to the track. His car was on consistent car. On the dyno and the track. His car was perfect. with the long tubes installed, his car did MPH more. was it a fluke? I don't know. My other buddy johns cobra also MPH more when he installed long tubes but saw minimal hp gains. did the car become more efficient? again were they flukes? if your pumping out a lot of power, have a big build, have a big blower, IMO, long tubes are the way to go. I am not saying go isntall 1 7/8 long tubes. I have mac long tubes 1 5/8. and I did feel a difference in the car after we installed them. and without dropping names, a famous company actually copied macs design for fitment purposes.
 

c6zhombre

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you are just looking at hp numbers. That magical screen that people obsess over. The stock manifolds are good. On certain setups. Once you start going with a big blower, built motor, the long tubes will help. Long tubes dissipate heat much better than the stock manifolds. Now add more boost, everything gets hotter. Its a more efficient setup. And, you were around since late 02 into 03, jimmy vaccaro, the god father of mustangs we call used to call him, did long tubes on his ported eaton. He wasn't concerened on the HP numbers. BC he knew on the eaton, nothing would be gained. when he did the long tubes, the same month, he brought the car to the track. His car was on consistent car. On the dyno and the track. His car was perfect. with the long tubes installed, his car did MPH more. was it a fluke? I don't know. My other buddy johns cobra also MPH more when he installed long tubes but saw minimal hp gains. did the car become more efficient? again were they flukes? if your pumping out a lot of power, have a big build, have a big blower, IMO, long tubes are the way to go. I am not saying go isntall 1 7/8 long tubes. I have mac long tubes 1 5/8. and I did feel a difference in the car after we installed them. and without dropping names, a famous company actually copied macs design for fitment purposes.

You won't get any disagreement from me.....I have no doubt LT will trap a bit more. Drag racers are looking for every last bit of potential....even when the bang for buck$ is not very good. But a couple more mph might very well be worth it to them. That could be the difference in win/loss.
 

stangfreak

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I guess when the cobra came out, we all got jaded. we saw how much power they made, how easy it was to make power back then, built motor from ford, that everyone just wanted to squeeze out as much hp as possible lol. so they started with the throttle bodies, long tubes. I guess for the weekend guy, adding long tubes may not be a mod for them. I honestly just liked the fact that they can move air out quickly, dissipate the heat, and make a more efficient motor. I know on my setup with the 2.3 whipple I did pick up a lot of tq. The throttle response was better as well. But the stock manifolds like you said will still do the job to a certain degree.

I remember when hellion created the turbo kit for the cobra some guys backed off bc they still used the stock manifolds. But you didn't have to worry about the notorious header cracks when going turbo. John was pretty smart with that. I know a few of my friends asked hellion if they would do headers but at that time I believe they said no.
 

ITSTOCK

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Definitely not bad, but they are expensive for a quality set that doesn't leak and they are a bitch to install if you don't have an engine support bar. If you are doing long tubes, just do the k member at the same time. Long tubes aren't worth it on an eaton car unless you are going for some kind of old school max effort eaton to prove whatever point it is.

Yes and yes.

This isn't the only 2.3 whipple car on the forum that has made past 700. Some have even run in the 9s.

I've been in the 9's at full weight and the 2.3....but I have long tubes :p
 

Rambro

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you are just looking at hp numbers. That magical screen that people obsess over. The stock manifolds are good. On certain setups. Once you start going with a big blower, built motor, the long tubes will help. Long tubes dissipate heat much better than the stock manifolds. Now add more boost, everything gets hotter. Its a more efficient setup. And, you were around since late 02 into 03, jimmy vaccaro, the god father of mustangs we call used to call him, did long tubes on his ported eaton. He wasn't concerened on the HP numbers. BC he knew on the eaton, nothing would be gained. when he did the long tubes, the same month, he brought the car to the track. His car was on consistent car. On the dyno and the track. His car was perfect. with the long tubes installed, his car did MPH more. was it a fluke? I don't know. My other buddy johns cobra also MPH more when he installed long tubes but saw minimal hp gains. did the car become more efficient? again were they flukes? if your pumping out a lot of power, have a big build, have a big blower, IMO, long tubes are the way to go. I am not saying go isntall 1 7/8 long tubes. I have mac long tubes 1 5/8. and I did feel a difference in the car after we installed them. and without dropping names, a famous company actually copied macs design for fitment purposes.
Yeah, I really shouldn't look too hard into dyno numbers. I've never questioned the sound, and they do drop boost so you can spin the blower harder. A friend of mine has kooks and they sound amazing and fit well on his car.
 

BlckBox04

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When I first did headers I went with Mac. Fit and sounded good but rusted. When I did my teksid build I bought some kooks. Love my kooks setup.

When I bought my car it already had bbk and just like you it fits and sounds good but they rusted also. All the guys I knew who had kooks had the best sounding cars.
 

Black02GT

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Yes and yes.

This isn't the only 2.3 whipple car on the forum that has made past 700. Some have even run in the 9s.

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).
 

SVTdreamin04

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I have MAC long tubes on my car... when putting the engine back in from the top, I no longer wanted MAC long tubes or any long tube headers. It sucked, sucked so bad. Lol.

But it sounds amazing!!!


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holiks03cobra

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I have MAC long tubes on my car... when putting the engine back in from the top, I no longer wanted MAC long tubes or any long tube headers. It sucked, sucked so bad. Lol.

But it sounds amazing!!!


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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.
 

roy_1031

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That's the true way to compare.....unless you are already at the max operating rpm the blower can spin. Pretty much where I'm at. I'm already spinning this blower max (I think). I guess if I added long tubes I could try a 2lb lower....but I'm probably already pressing my luck with current blower rpm.

If I added long tubes......I'd be adding a new gen4 2.9 or gen5 3.0 as well. And then head studs. Built T56. Solid rear. Holycrap.....ya, I'm not going down that rabbit hole lol. I'm pleased as is.

24d61f8f1fafd1fd37b7abaa59c71bfc.jpg




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KBR

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I gained 13hp and 71tq by adding Mac LT headers and 4lb lower. It was on the same dyno, but completely different weather on the 2 runs about a year apart. Tuner said it was
101600467_10158446411547427_7188730648738136064_o.jpg
not a good day for numbers. VMP 2.3 670hp/654tq 20.4 lbs boost 93 and torco.
 

Black02GT

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I gained 13hp and 71tq by adding Mac LT headers and 4lb lower. It was on the same dyno, but completely different weather on the 2 runs about a year apart. Tuner said it was View attachment 1643940 not a good day for numbers. VMP 2.3 670hp/654tq 20.4 lbs boost 93 and torco.

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

Out of curiosity what size upper?
 

JAJ

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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.
 

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