Shorty & LT Comparison Pulls

[reddy351]

What we have here is Grady doing the "driving it everywhere I possibly can" and 5sp GT talking about ONLY the track. 5spd ir right. At the drag strip, you get to redline and shift, back to what, 4500rpm? When you drive on the street, you get to see 700 rpm to 6000 rpm and everything in between. So, in that respect Grady is "spot on". In fact, both are correct, with their respective "arguements".

The problem is, they are trying to compare one's apple to the other's oranges. They are two totally different circumstances. I gather (from their points) that if you want a nice powerful "stoplight to stoplight" combo, go with longtubes. If you are concerned with "redline and shift" you can use either one, with the same result either way.

Am I right?

 

[wytstang]

reddy351 I agree with your assessment. Grady thank you for sorta doing the homework and showing the class so we can all copy your work for an easy A+

 

[final5-0]

Well

It was not but a few days ago David and myself made mention in some
thread or the other about the peak hp difference between shortys and
LT's was not enough to fuss about

Sure ... its always about application
and
If we would admit it ..........
Our personal likes and dislikes drive the application

I have no problems what so ever
giving up a bit of peak high range power
for a stronger low & mid range :Word:

Torque is so much fun when cruising around town

Now ... in my younger days when I lived at my local 1/4 strip
That kind of thinking would not have been as important to me

O Yeah ... about the tko trans ... I gotta throw in with David
They do sap a bit of power

Hummm 3% ... On a 300rwhp combo ... about 9rwhp less than a t-5

I would have thought around 5rwhp but that is just a guess.

I really have no factual data but the tendencies are there .......
I usually deduct 5 more if I see a tko trans is listed

Grady

 

[Pokageek]

Don't forget if you have an auto, the long tubes should make a huge difference. The auto can spool up much faster with more tq down low...at the very least round town.

TAke for example 2 cars. The old 300ZTT with AUTO and the 285HP LT1 AUTO I had:

STICK ->300Z Twin Turbo 300HP 0-60 of around 5.5 seconds.
STICK ->Z28 5.7LT1 285HP 0-60 around 5.6-5.8 seconds.

AUTO-> 300Z Twin Turbo AUTOMATIC 0-60 roughly 8.0 seconds.
AUTO-> Z28 5.7LT1 285HP AUTOMATIC 0-60 around 6.2 seconds. *WINNER LOW END TQ

Then put a load of sandbags in the nack of each and watch the 300Z REALLY lose.
Drive them up a hill...you get the point.

 

[Killercanary]

5spd_GT touched one exactly what I was going to say in that on the track, I think there would be little difference between the two combos because in the RPM range that the car would be in going down the track, the difference in power is very little. Look at 4250 and up and you will see what I mean.

I had considered swapping to LT's for a long time, what made me decide against it was the results that GMKILLR had when he swapped his shorties for LT's way back when he was NA. It just didn't pick up enough IMO to make the swap worthwhile.

On the street however, the long tubes would definitely be more fun to drive while just cruising around town. Assuming that is my curve with the shorties, I no doubt would have liked the low end gain in a way... and in a way I may not have. I mean my car was pretty deadly on the street because it would hook and go 100% of the time in 2nd gear and up, and in 1st gear it'd stick about 50% of the time. If I had an extra 50ftlbs of TQ down low I doubt I would have had the same results. Its really a non-issue anyway since I don't street race, but I can tell you that my new combo doesn't have a prayer of hooking in 1st and 50% of the time it'll howl the 315 DR's right off in 2nd.

 

[final5-0]

Yes Paul

That is your Vert

I didn't think you would mind but I omitted the owners names anyway

We all know that difference didn't hold Paul back at the strip :Word:

I only picked those two combos because I happened to notice how
similar they were as I was poking around in my files looking
for other data.

Grady

 

[Grn92LX]

I did the shorty to LT swap on my old 302 combo 4 years ago. It definatly pulled better down low and made more power down there.

Another thing people need to look at is the cheaper LT's vs the good LT's like hookers, kooks ect. The better (more money) lt's are equal length design and have a MUCH better non restrictive collector and will make more power through out the rpm band. The bbk's are good enough for most due to cost and they drop right in.

 

[final5-0]

I did the shorty to LT swap on my old 302 combo 4 years ago. It definatly pulled better down low and made more power down there.

Another thing people need to look at is the cheaper LT's vs the good LT's like hookers, kooks ect. The better (more money) lt's are equal length design and have a MUCH better non restrictive collector and will make more power through out the rpm band. The bbk's are good enough for most due to cost and they drop right in.

Mike has lots of good stuff to say here

Just to show you a bit more about how headers can pull the exhaust
pulses of each other for more power.

Here is an old drag racers trick ...
which I've used on more than one occasion

btw ... this is in a race only application when running open headers

With race style headers ... you can bolt on collector extensions.
You paint them with some cheap spray paint
The point of where you see the color change ... you cut them there

The idea is to make the gas exit at the perfect place
thus increasing the scavenging effectiveness

That little trick can be good for an easy tenth in the 1/4

Grady

 

[5spd GT]

I did the shorty to LT swap on my old 302 combo 4 years ago. It definatly pulled better down low and made more power down there.

Another thing people need to look at is the cheaper LT's vs the good LT's like hookers, kooks ect. The better (more money) lt's are equal length design and have a MUCH better non restrictive collector and will make more power through out the rpm band. The bbk's are good enough for most due to cost and they drop right in.

It's hard to base things off of seat of the pants.

I read all the time how equal vs. non-equal length is an extremely small difference.

Those type headers are for the guys that want to get everything they can. And on top of that, would it not be fair to compare a good quality shorty header to a good quality longtube header like you mentioned. Not, a Mac to a Hooker Seems like the test wouldn't be so bias afterall...

The 2.33" collector isn't restrictive on a 302, believe it or not. It provides a nice seal and is just under the size of the 2.5" midpipe. I would look at the collector being a 1-2hp restriction in a 450+hp car.

Longtube and the matching H-pipe are heavier, I know that much, so for the extremely weight conscious...

Oh, an extra tidbit The old runs I was had where I gained 1.3mph on the new ones. Well the old mph numbers had a crushed H-pipe, it crushed into half of the H-pipe, therefore making it a 1.25+ pipe at one point. I swapped on NEW LONGTUBES/OFFROAD HPipe, and gained 1.3mph with the other stuff. So I'd venture to say the collector isn't a restriction at 2.33", if my Hpipe wasn't a restriction at 1.25", believe it or not. I sold that pipe anyways

 

[WhiteDevil]

This thread is killing my hope of makign more power with my long tubes. Im hoping that my 1 5/8 shorties were a restriction to my 347 and with my 1 3/4 long tubes i can pick up 5-10hp. I am very happy with the sound though my freeway drone is GONE, i can actually talk to someone in my car on the freeway now. Its a little quieter all around and real crisp!

 

[Grn92LX]

The 2.33" collector isn't restrictive on a 302, believe it or not. It provides a nice seal and is just under the size of the 2.5" midpipe. I would look at the collector being a 1-2hp restriction in a 450+hp car.

To quote my custom cam grinder, Ed Curtis, 4 years ago when I asked him about the bbk LT swap.."Be sure to open up the collector, its tiny down there"

 

[5spd GT]

To quote my custom cam grinder, Ed Curtis, 4 years ago when I asked him about the bbk LT swap.."Be sure to open up the collector, its tiny down there"

I have not seen a dyno or track gain. Do you think 1/10th of an inch is going to blow the tires off

I recall you saying that about the 347 and your 1 3/4" headers. Not the 1 5/8".

WhiteDevil - On the 347 you very well could...but it depends on what your cam was ground for and the valve timing associated with it - sooner or later opening/closing events.

There was a thread not to long ago where a guy lost 13-14rwhp by swapping from 1 5/8 to 1 3/4" longtubes on his 347. But again, it depends on how the cam was ground...

 

[Pokageek]

"Do you think 1/10th of an inch is going to blow the tires off"