stereomandan

So the dyno proven 30 ft. lbs. of torque you get from MAC mids with 1 5/8" primaries sucks huh? Even after PROVEn gains, people still say LT's are SO much better. I disagree, based on data, not SOTP differences. Of coarse there are cases where LT's are more useful if the engine is large enough, with a big enough cam where they are beneficial.

The more I keep reading how much better LT's are then Mids, the more it makes me want to spend the cash to dyno before and after. Then again, it's already been PROVEN that mids are a great increase in TQ and HP.

Did you look at the link from 94formulabz that showed 1 5/8" primaries to be better than 1 3/4" primaries up to 5500 RPM? It promotes better exhaust speed and, thus better scavenging.

Dan

12SCNDZ

...Um...I can't say I'm "real disappointed" with my 12.0 @ 112 MPH at all.
Let's see, you've got the same cam as I do, but you're running LTs...Wanna volunteer any quarter mile times?
I know..I know. I've got ported heads, and you don't. Well the extra 50 HP you guys "claim" your LTs make should offset that, right?
Feel free to bookmark this thread, so you can let us know what it runs when you get the ported heads on.

Frank

Cmr0z28

I'm with Frank here....

Guy I know running Mac mid length's in a '97 Z28, absolutely bone stock engine - never had the valve covers off...full exhaust, CAI, 125 shot, M6 + traction, and ran an 11.3. Oh, and they were the "useless" 96-97 style.

baron4406

I guess I'll weigh in here. I have a '95 Z that I put Hooker LT's on, at the same time I put on a CSI elec. waterpump. Before the swap my car ran 13.8's at 102 MPH mostly stock with just a Flowmaster catback and a homemade CAI. After the swap it ran 13.6's at 102. What was bizarre is that I didn't pick up ANY MPH which means I got ZERO hp increase from LT's. The faster ET was most likely from the dimished low end torque and better 60 foot times. I posted this last year and was blasted by the LT crown. There had to be SOMETHING wrong with my car. Most blamed my "Crappy Flowmaster". So I put a cutout on. With the cutout open the car ran the same. So much for the "experts" trashing my Flowmaster. So you see some guys think LT's are the bomb, and some think they are junk. I think I know why and I can assure you this is true. LT's were WAY too big for my combination-meaning a mostly stock A4, 2.73 geared setup. Yes I actually gained .2 in ET, however the lack of MPH increse is telling. Take that same LT swap and put it on a mostly stock 6 speed,3,54 geared LT1 and the owner will see huge gains. Lets say I waited to swap in my LT's until I put 3.73 gears in, and a 2800 stall converter. I'd bet I'd see the .3 ET, 3 MPH gains people associate with LT's. So yes they are coming off this year, mainly since PA implemented emissions and I need a set of emnissions headers. So match the headers to your combo. If you have a high geared (low numerically) car then LT's may not be much of a help. If you have lower gears and a manual trans, then LT's may be the bomb. Hmmmmm, this is what held true for older musclecars too. How things change, but how they stay the same!!

Zepp

Don't you think that I would have tried to justify the heads instead of the long tubes since they cost me almost 3 times as much?

There are reasons why you will see many of us without dyno numbers and times listed here. Think about it for a minute....

There are a lot of people here that race for money. Why don't you come on down to Houston and find out what that 350 of yours will do? We will bring you out for a night on the town. Just bring a lot of money because there are several guys here that will gladly race you for it. 12 second cars in Houston are just average. You want to find out what the stroker will do, come on down and get yourself some.

I am sure you have a nice car. But remember there is always someone faster than you. Pick your fights wisely.

12SCNDZ

You went from manifolds to LT's and only picked up .2? Thanks for the confirmation to my theory. I've seen better gains than that going from manifolds to MACs.
As for all those guys bashing our Flowmasters? I run 12.2 through it, and 12.0 with my cut-out open.
Intersting thoughts about the "more car needing LT's"? I've got a tiny CC305 cam, and ported heads, and my MACs are working for me.

BTW, 13.6's are pretty impressive for a car with 2.73 gears.

Frank

12SCNDZ

How did this turn into a "My buddys got a car that'll outrun ya" post? Use whatever excuses you'd like. The fact is you're either scared or ashamed to post any times.
You're right...12.0 is still kinda slow...but, doesn't that make you feel foolish...because you KNOW it's faster than you?
I never claimed to be the quickest. I just claimed to be quicker than you. Have you ever even SEEN a dragstrip?
Street racing for money? I aint skeert. If the 12.0 isn't enough, I've got a little white bottle too.

Frank

Zepp

Yeah, that must be it, i'm scared. BTW, we have one the fastest tracks on the NHRA circuit right here in Houston. Why don't you come on down and get yourself some.

To get back on topic. Anything has got to be better than stock manifolds. But you can't go wrong with either mids or LTs for best performance.

Fastbird93

How about we get this thread back on track and the point of it and quit the "I'm scared" and "my friends-friend has a friend whose car is faster than yours" BS before this good thread gets locked.

If you want longtubes, go for it. I just personally don't put as much stock as the masses seem to. I've seen plenty of cars with shorties and mid-length, BOTH 1 5/8 and 1 3/4, put down just as much power as a long tube car, and vice versa. There have been dyno proven facts that the shorties and mid-length designs help up high, and that the LT helps down low.

Power is power, and no two products are alike. Instead of everyone constantly sayins "this" is better than "that", maily because the "this" product is on said persons car, why not just own up to the fact that different cars WILL respond differently to the exact same thing.

That said, why not just weigh what people have gained from their specific combinations and instead of asking what to go with, make an educated unbaised descision?

stereomandan

Agreed.

I see VERY similar dyno numbers for guys with LT's and those with Mids. Just go with what works best for the other components you have, such as cam, intake, cubic inches...

For me with stock heads, and a mild cam in the future(CC502, CC305...), the Mid's will actually be better than LT's. Plus, the install will be much easier and is less expensive.

Dan

juiced_lt1

Sorry about that stupid post I gave earlier I love making dumb comments... I have a little time today so I wrote a paper for yall.

Well, I've gotta find the dyno sheets, they are around here somewhere...I'll post em soon.

Shorties shift the torque curve over to the upper RPMs where as LTs shift the torque curve to lower RPM's. Remember that horsepower is a function of torque when you read this:

(Torque x RPMs)
--------------------- = Horsepower
5252

Also, your cam/heads is a BIG factor. Large cams like the cc306 coupled with ported heads also shift the torque curve to the higher rpms, where as a stock cam keeps the torque curve in the lower rpm's.

If you run shorty headers with a cc306 and ported heads, your torque curve will be so far into the upper rpms that you will have to be hitting 4k-5k rpms to get into your powerband. Whereas if you run a stock cam with LT's, your powerband will be in the lower rpms and drop off some in the higher rpms.

The reason people FEEL like there car runs better with LT's is because they get a significant torque increase down low, as well as a lot more low end horsepower.

If you have a big cam like the cc306 and ported heads, your power band is already going to be way into your RPM's. So, if you plan on staying WAY into the red, get shorty's with 1.75" primaries for breathing purposes cause you'll be moving so much air, but remember that your bottom end ( <3000rpm ) is going to suffer. However, if you don't want to sacrifice any more low end power than what you already have by going with a big cam and ported heads w/ larger valves, go with longtubes because it will move your torque curve back 500-1000rpms, and possibly help flatten it out, giving it more average torque and horsepower, depending on what cam/heads combo you have.

As for stock heads and cam, going with LT's will help you down low, but not really any on the top end. Yes, they flow better than stock, so that free's up a little horsepower, but since it the torque curve drops off sooner in the rpms, it cancels out any free'd up power that the extra flow got you. Your 60' and E.T. will be lower as long as you can hook up, but your trap speed won't be much better. Shorties will move your torque curve to higher rpms, where a stock LT1 normally suffers, so you will gain a good amount of top end power because the torque is moved to the higher RPM's AND they flow better than stock manifolds. On the track, since shorties flow better but move the torque curve to higher rpms, it cancels out any low end gain, so your launch won't be helped any, but your trap speed and ET should improve a good bit.

As an example, I'm running nitrous and a stock cam/heads, so I went with shorties with 1.75" primaries. Since nitrous really needs a good flowing exhaust, I went with the big primaries, and a cutout. The short primary tubes will also help move the power I get from the nitrous into the higher rpms for an extra increase in top end when I'm on the bottle.

FastWhiteTA

When you said "...Um...I can't say I'm "real disappointed" with my 12.0 @ 112 MPH at all.
Let's see, you've got the same cam as I do, but you're running LTs...Wanna volunteer any quarter mile times?
I know..I know. I've got ported heads, and you don't. Well the extra 50 HP you guys "claim" your LTs make should offset that, right?
Feel free to bookmark this thread, so you can let us know what it runs when you get the ported heads on.

Frank"

So...you're wanting me to post times so you can say your car is faster than mine.

And you're 50 hp statement was pretty damn stupid. Find one post where I said 50 hp. Did you find it yet?



Yet?



YET??

Guess not huh?

But you know what, If you like the midlengths good, I didn't like my Hooker shorties that's for sure compared to the jet hots. AND, 12.0 w/ a CC305, that is impressive, good job.

stereomandan

juiced_lt1, good reading, and I agree with you about the times when LT's are better, and when are be better.

It's nice to see that the blanket statement "Get LT's" is starting to go away. I have been so tired of seeing that on this board with no good data to back it up.

Like you said, it depends on the setup.

Dan

baron4406

Well Frank don't forget the LT's killed my bottom end, that's why I went .2 faster in the 1/4. When you do a mod and get no MPH increase that's all you need to know right there. LT's gave my combination very little HP increase-in fact the increase I got could have come from the electric waterpump. BTW thanks for the kudo's on my 2.73 geared car. It kinda made me laugh that guys were telling me I had problems with my car. Uh right, name me another A4/2.73 combo that hit 101 MPH and 13.8's with a crappy Flowmaster and a $15 homemade CAI........in 90 deg heat no less!! Like I said before, all the old time hot rod rules still apply. For a mild combination 1 3/4 full length headers may be too much, look at my car. If I end up keeping the thing (its for sale) I'm getting Mac's and prepare for another can of worms opening when I post my first times of the year.

juiced_lt1

You got that right...I met a guy who just got LT's on his lt1 at the track last friday w/ a catback and cold air intake. He had 3.23 gears, and an A4. He went 13.8@102, with a 1.9 60ft. He couldn't understand how he spent $700 on the coated jet-hots and y-pipe and bettered his 60ft time by .2 but his car actually didn't pull as hard up top as it did with his uncoated shorties.