Is there any noticeable difference in performance or sound when comparing either on a 1977 L48 4spd that is basically stock but with a 2.5" true dual exhaust system? I have read VERY conflicting reviews online. Some say there is virtually no difference between a shorty header and a stock ramhorn and others say there is at least a 20hp difference that you can feel and hear immediately.

 

Shorty headers are like low restriction exhaust manifolds. Because of the short tube length, they aren't able to "tune", unlike a full header.

I wouldn't expect more than maybe 10 hp.

 

For not much more money you could find some full length headers that with minimal cutting should match up to your pipes.

 

Times 2!

 

I've run both shorty and full length headers on my 80 but after years or plug wires failing due to header heat and other wires, hoses, and steering coupler failing due to header heat I went with a cast iron solution. Don't have a problems with headers but the long term heat problems were not worth it.

You might be able to find earlier 2.5 exhaust rams horns but might be hard to find. If one has a cast in bracket you may have to grind it off.

I ended up going with Sanderson (sp?) cast iron headers ceramic coated. I run these to my Hooker side pipe tubes. More expensive but I have a lot less heat in the engine compartment and for track days it get enough performance out of them. Oh and never had an exhaust gasket failure.

Dave

 

I agree with everything said. There is a difference. Shorty headers flow a little better than the rams horns and full length headers flow better than the shorties. Those 2.5" rams horns are a rare breed as mentioned above. A lot of that has to do with street stock type racing classes like I run in that mandate a "stock" exhaust manifold.

 

My manifolds are stock. Are they the 2.5" ram horns? If so.. maybe I should just keep them and just order the 2.5" true dual exhaust kit from Corvette Central.

 

I finally got tired of fighting Header Heat problems also,
The corvette manifolds are some of the best flowing cast manifold made, use them.
keep the Manifolds, say good by to the hassles of headers.
I like the OEM manifolds and the side pipes myself.
good luck on your choice,

 

I'm not sure which ones you have and I don't have the part # handy of the 2 1/2" manifolds. You could Google the manifold number and see what comes up. If they're the 2 1/2" I'd keep 'em and just add the exhaust kit.

 

I have long tubes on my 73. They've been on for 12 years. Never had any of the stated heat issues. Just lucky I guess

 

Speedway motors has ramshorn manifolds but they are different than factory, but are probably a better design. I vote for ceramic coated long tubes. I've never been convinced that headers are any hotter running.

 

running headers - no burnt plug wires ? no mystery misses? no blown gaskets? no headers dragging the ground ?
if you have gone 12 years with none of these issues you are Lucky !

 

Rams Horns are good into the 350 HP or so range...but definitely need to be 2.5". You can get import versions that work great for low $$$.

Smallblocks have more challenges to gaskets due to the center ports being sealed by only two bolts vs 4. Big blocks have 2 bolts on each port so no issues. The trick is to get decent headers with a thick flange and use good gaskets. Good headers don't hang too low. I had some Hedman's on a small block that were terrible. Hung low, bad access to plugs etc. No excuse for that. I've used some nice Hookers that were much better. (don't go there!!)

Coated header help the heat situation a lot...and carefully routing plug wires and using insulator boots takes care of them. Routing them in from underneath takes longer...but usually works great and looks cleaner to me. I've even got them coming from underneath on my twin turbo big block.


JIM

 

That's the difference between cheap headers and quality made headers.

My American Racing Headers have no issues. And they are 1 7/8ths tube size.

 

The G. M. factory shorty headers, the restoration book said; came on 1980, CA. cars, & all 1981-82 cars, were Stainless steel. The factory headers, the book said; Added 7 to 14 horse power. They have 2 " outlets. If you want the full 2.5 outlet in the same shorty, buy a set of used 84 up model headers. I had no trouble in feeling the added horse-power with the 2 outlets, I did buy a set of the 2.5 off an 86 for my 77 project. Aren't these cars a lot of fun. Gene

 

I'm using Mid-Year Ramhorns and like them very much. The exhaust manifolds have the same casting numbers on both sides, #3797942. Also the casting seams were ground smooth and a high temperature coating was applied inside and out to keep them from rusting. I'm using a stainless steel chambered exhaust, no mufflers, no cats.

 

Shorty vs manifold stock engine noticeable no, more HP shorty yes. Long tube style would be maybe 15-20hp. The low end torque is the SOP that people talk about with long tubes or the noticeable gain.

 

Shorties versus Ram horns versus LTH?

In just about any application on a stockish type motor, up to about 350 Gross HP, the shorties are better than the ram horns, and the LTH's better than both but not by much. Those that say Shorties are not better than the ram horns on stockish motors less than 350 Gross HP, I disagree. Why do I say this? Personal experience with all of these types of exhaust manifolds.

I have found over 35 years of playing with cars that the biggest HP gains by far can be found with going with a 2.5 inch dual exhaust over a single exhaust, not so much the headers on a stock motor. Do they help? Yes but the headers are not the major contributor to HP gains-Its the 2.5 duals. I had a 73 Nova with a single exhaust on a stock motor and went to LTH's and 2.5 inch exhaust...big HP gain. Can't be sure about what was really responsible for the gains-2.5 duals or LTH's or both.

Recently added a magna flow cat back system 2.5 semi duals to a 2001 Pontiac GP along with U bend delete in the single front pipe (stock GM cat), no headers from the stock 2 1/4 inch single exhaust...noticeable gain in power.

1994 Mustang GT (stock)-added a magna flow cat back 2.5 inch duals versus stock duals first..no much difference in power. Later replaced Ford Shorty headers with VERY small primaries with BBK shorties with 1 5/8 inch primaries...engine was noticeably louder..more airflow.Then later replaced Ford H pipe (4 cats) with magna flow X pipe with 4 high flow cats...Louder again and more HP. Noticeable difference. No LTH's.

On the stock 78 L-82, originally added cat test pipe in place of the GM cat-some difference in power..Then added 2.5 duals and Monza Turbo Mufflers-GM ram horns...BIG difference in power...later added 1 5/8 inch shorties to the 2.5 duals...noticeable difference in power...Motor louder in all RPM ranges. Lastly, planning on added ARH LTH's since the new rebuilt L-82 355 now makes over 425 Gross HP and the shorties are probably hurting some mid to top end power...key word 425 Gross HP.

Forum member Karol added 2.5 magna flow duals to his stock L-82 with a mild cam of unknown origin and 882 heads with ram horns and he had a BIG increase in power-248 RWHP versus my stock L-82 with shorties and 2.5 inch duals of 233 RWHP. I doubt he would see much more HP with LTH versus shorties on his combo for a street engine with that type of HP.

Lastly, my engine builder who built my L-82 short block sees 40 HP with LTH on C6Z06's with NO OTHER CHANGES but LTH's and new different exhaust from the stock exhaust versus the Stock Z06 shorties/exhaust BUT the LS7 is making 505 NET HP stock.

Conclusion, The biggest HP gains possible from LTH's are from engines with big HP. Shorties are very good on stock type motors with 2.5 inch duals and both are better than RamHorns. The biggest bang for the buck on stock type motors are 2.5 inch duals with free flowing mufflers, headers or not. Just my experience.

 

When I rebuilt, I went with after-market 2.5" ram horns in conjunction with my dual 2.5" exhaust. I paid $90 for both and had to do a little work (grind off the accessory brackets and port match). The reason: I wanted a stock look, didn't want the heat from uncoated headers, didn't want to loose any more low end power (that happened when I switched to 2.5" dual exhaust) and didn't want to pay the price tag for the shorties. I don't have anything to compare it to aside from some other forum members who went the same route, but I can tell you I have been more than happy with the results.

 

The ramhorns on my 77 are the small ones. I can't see the casting numbers but they are stock and they look small. I am not really looking for more power. The car has plenty of power for me. The L48 is fresh and the 4spd is completely rebuilt. I am more interested in the sound and the cosmetic look of a clean header based exhaust system. I may still go the side pipe route. I think there is a cheap way to do it. I just haven't figured it out completely.