Just wondering what would one could expect on a third gen tpi 350 in terms of power gains. how much better are shorty headers compared to stock exhaust manifolds? how much better are the long tubes compared to the shorty style?

shorty headers over stock manifolds. big deal. do that. long tubes are my preferred header choice if I can get them to fit. they have better overall power numbers. if you can get them and fit them i'd go for them for sure.

first off shorty headers are nothing more than free flowing manifolds long tube headers are great for low end torque thats about all i can tell u so good luck .....

yup free flowing manifolds that weigh less. Long tube's are better for all around performance.

Yup--I just put Hedman shorties on my 305 and saw about a 10% increase in power and mileage. Check out the EBay long tubes on another exhaust thread.

As said before. A good set of Shorties are worth a 20hp on a L98 compared to the factory manifolds.

But Long Tubes are where its at. LT's will give you a BIG gain, more so the higher the engine speed.

LT1's gain a good 40hp easy with LTs.

For what its worth my B-body LT1 is rated at 260hp factory. I have CAI, Tune, Hooker 2055 shortie's and a SLP 2otL cat-back. The HP estimators say that at a race weight of 3770lbs (yes its that heavy, I weighed it at the track) I was trapping 103mph.

The estimators say I'm making 320hp or so at the crank. Some say 330h, others a little less.

320hp compared to 260hp stock, thats a 60hp gain from CAI, Tune, full exhaust. I'd expect an L98 to gain a similar amount with full bolt-ons when shorties are used.

I'd really like to see those numbers in my car. When I talk about a gain in power, I'm hoping to see maybe 200 hp out of the stock 305. It's enough to have a little fun but as long as that 305 is in there the car will look faster than it is, not a good situation. For now it gets really excellent mileage but it's not going to beat anybody.
They say making an LT4 out of an LT1 is just the cam and valve springs--have you done this? You already have the exhaust--what intake is it?

To make an LT1 into a LT4 you need to change to LT4 heads, LT4 intake, and the LT4 cam. The LT1 intake and heads have raised intake ports and are physically incompatible with each-there without serious work.

Its easier to simply port what you have. Which i've done (paid someone to do).
http://gallery.me.com/thirdgen89gta#...lack&view=grid

Heads flow almost 290cfm intake, intake has been seriously ported, matched to 1205. And I have a mild Lloyd Elliot cam 226/232 on a 110LSA to go with it. Numbers say 400rwhp+, which I pray for.

Friend of mine has similar stuff, LE2.2 setup with roughly the same cam, but bigger 112LSA, he made 408rwhp n/a through a 3.70 9". If I can get anywhere near that I'll be ecstatic.

I also have Long Tubes for the swap compared to my shorties. I'll be selling my shorties mid-june. Ceramic coated Hooker 2055's if anyone is interested.

https://www.thirdgen.org/forums/exha...e-headers.html

I don't think long tube headers are all they're made out to be. Stick with shorties.

No matter the exhaust, Thirdgen89GTA's porting is a work of art. What they did with the valve guide bosses is beautiful--no wonder they flow 290 cfm. Port matched to a ported intake and exhaust he thinks is right means very little restriction=power. Very, very nice. I haven't heard of Lloyd Elliot cams but it's making great power. I ran Iskendarian cams for years, now Crane because of the tech backup. At some point, length and diameter of primaries has got to count--I'm just not there yet, doing very well with 1.5" primaries in shorties.
Those coated Hooker 2055's will go fast--they get high marks on this site.
I'm building a '78 350 with flat tops, Patriot small port aluminum heads, mild Lunati Voodoo cam and Weiand Street Warrior intake to fit under the stock hood. FAST Fuel is burning a chip for the original computer and tuning the Qjet to match so it will be stock appearing. I might even paint the aluminum black. Planning for 325-350 hp at the motor, enough to have some fun but not too much for the WC T5.
I drive this car to the Rockies and the Ozarks, or the East and West coasts, every year so mileage matters.

Much thanks, I will pass your comments on to the porter. When I saw the pics I got chills and later giddy. I had this slightly maniacal laugh, kind of mad scientist like. Still need to put it all together. These heads are going to really come alive at higher engine speeds. He went much further with the heads than I anticipated. I was expecting something like a LE1 setup which is about 260cfm on the intake. He went MUCH further on the heads than I expected, then he further offered to port the intake and the throttle body out for me as well. I got a smokin deal on them.

As for LT vs Shorties? With the LT1 crowd comparing Shorties to LT's the LTs win every time. But then again, unlike the L98, the LT1 engines LIKE to be spun to 6k. And once you start getting into cams that work with the factory casting heads and lt1 intake its no wonder that long tubes are the only way to go.

The 2055's are 1 5/8" primaries. The Hooker 2210's I have are 1 3/4" primaries and are considered the better choices for headers.

A real custom set is better ofcourse, but where am I gonna pick up a set like that for what I paid for these 2210's used.

Just for general interest there is a thread comparing long tube headers with short tube headers on an L98. This was on an engine dyno.

https://www.thirdgen.org/forums/exha...long-tube.html

There's a lot of information in there--very interesting. After installing these Hedman 1 1/2" shorties I can appreciate installing 1 5/8" or 1 3/4" primaries, then snaking pipes underneath and still having ground clearance. Good grief--but it's obviously worth it; that's serious power.

Its my opinion on a street car that sees little track time, shorty headers will be well worth it. Long tube headers have fitment issues, are lower to the ground, and I think they're also harder to change spark plugs. If you have a race car, or a car that spends more time at the track than the street, and you want every little bit of power and torque you can get, and you're willing to put up with the hassle of scraping over every speed bump and driveway, and the routing issues of getting the y-pipe around your transmission, then long tubes are for you.

Hooker 2055's are JUST as hard to change the plugs on.

And my car will see PLENTY of track time when its done ready for it.

We here in Southern California are making good power using Dyno Don's short tube headers. They also clear the spark plugs quite well and they are 1 3/4". We are talking 400+rwhp cars.

Do the 400 rwhp cars meet California emissions? I moved to West Texas from SoCal largely to get away from the CARB but they're gradually catching up with me anyway--might have to learn your technology.

"Do the 400 rwhp cars meet California emissions? "

Yes they do. They pass the visual and the sniffer. All smog equipment is present and accounted for.

well i have long tube headers and custom 3 inch y pipe that goes under the transmission pan and i rarely scrape unless i go over speed bumps.... the only place to put my exhaust is under the pan anyways because my alston and bmr subframe connectors are in the way of the stock exhaust routing.. so even if i did you shorty headers it would still have to be under the pan so i said minus well go with long tube headers...im glad i did.. the low end power was alot better than the stock manifolds and they made my car sound alot better and more distinct...

That's amazing you can get that kind of power and meet Calif. smog--excellent. Is it some type of super efficient EFI? Naturally aspirated? Apparently the long tube headers make a difference at that level. I doubt I'll ever do that with my car, use it to visit friends in Calif. and the East Coast every year, finding new windy roads. Still, that level of power, if dependable and gets reasonable mileage, would make a heck of a road car.

Are dyno don's Long tubes?

No

I thought so and kind of knew that. But the guy before me was acting as if they were so I was more implying that they were not. Very nice header. When I upgrade their deffinately going to be the option Don.

I just ran a 11.57 @ 115.73 on Dyno Dons headers. This is a fully loaded GTA that passes California emissions. They are a very good set of headers and exhaust system.

that's a stout number! GREAT WORK! someday I will be upgrading my small edelbrocks and Don's will be in the running for sure

Holy mackeral! In the 11's in a street driven, emissions compliant door slammer. Hot rodding is alive again in California. Is it naturally aspirated?

"Is it naturally aspirated?"

Good question. The answer is yes it is naturally aspirated. In fact at the track today I had N/A on the car to prove the point along with "Tuned Port Injection" just to let people know.

Man, I need to study up on that. Is this car driveable in traffic? Would you drive it to Las Vegas? There's something going on here, and I don't know what it is...

I know.... this is an old thread but, the answer has always been the same from an engineering stand point here it is.

All other things being equal, shorter tubes produce less torque at low rpm. This is because the pulse of the hot expanding gasses don't have enough time to help pull the exhaust pulse out. They also don't have as much of a gain in HP at low RPM's.

Think of it this way look at a top fuel dragster. Individual short tube headers. This is because modern slip clutch designs allow crew chiefs like me to tune the engine to a specific RPM where the clutch is going to hold the motor. And the RPM's are going to be high. Individual pipes with no collector are very "peaky" a very short HP range. Add a collector and you smooth out the peak.

The best rule of thumb is this, for lower RPM gains street ability and a broad HP and Torque range longer tubes work much better.

For High RPM's nothing works as good as "shorty's but you lose quite a bit of the bottom.

This is exactly the opposite of what you will find on all the Internet posts around. We have all heard be careful of information on the Internet. This one is definitely one of those cases. Before you ban me for blasphemy I suggest an old book that will help understand and sort this all out in great detail. I suggest you read Chapter two of STREET POWER by Jay Storer published by S-A design copy written a long time ago 1988 to be exact.

Bob

Interesting--Here's a crude observation: those cheap Hedman headers and Y-pipe have been in my car since May and I'm really happy with them. They might be mass produced and dipped in tar for shipment, but shorty or long tube they deliver a real mid-range punch to the butt dynometer, a great street header for stock or mildly modified small blocks.
They were relatively easy to install, have good ground clearance and after checking the bolts through a few heat cycles they remain nice, tight and leak free.
If I were building this car for a competitive edge, cost no object, I'd try Dyno Don shorties against a set of stainless long tubes and be more knowledgeable as to results, but I'm not.
Nonetheless, I love reading people's thoughts on this, agreeing with you about keeping the motor in its power band through clutch technology. In '63, I hung on the chicken wire in the pits at Lions Drag Strip, looking down into the individual pipes of AA fuel dragsters as they staged, the nitro bubbling on the rims of the pipes. When they took off they blasted that liquid nitro into our faces, undoubtedly changing the chemistry of our brains.

Your right on the money High Ranger! Those were the day's. I still remember that first (and last) blast of "stuff" in the face when they fired up those fuelers.

I believe you that your system works.... mine does too! I have the same system you mentioned. Absolutely anything that eliminates pressure in an exhaust system is a step in the right direction especially when you have a "cam" in it and other go fast goodies. The best thing you can do for a "cammed up" motor is isolate the cylinders. Dumping everything into a log type stock manifold forces burned hot gas into any cylinders that may have an intake valve open.

My car had a best et of 13.889@99.57mph with factory cast iron manifolds and factory dual cats. It did that time with a 2.037 60ft time. I bolted on jet Hot coated Hedman long tubes, and dynomax high flow 3" cats. Then the car went 13.710@101.42mph, with a 2.063 60ft time. My math puts that at about a .18 tenth gain, and 1.9mph faster. I expected a lot more than this, but my car is evil and it hates me. *shrugs*