Alfa Romeo Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
601 Posts
Discussion Starter #1
I am getting ready to purchase a GTA style header (possibly two sets as you will see) on my 65 Sprint GT race car.

I have two engines for the car, a 2-liter (in the car now) and a 1600 (being built). I'd lean toward a GTA replica system for the 1600 and a more typical "performance header" for the 2 liter. Both are race motors so performance is an issue.

The car has the original floor-mounted pedals.

Here are the systems I know of that would be of interest (some of this info boiled down from previous BB threads):

- Alfaholics stainless steel "sports" exhaust including header. Seems to be oriented toward a 2-L application, not strictly a replica of a GTA system.

- Centerline offers both a "performance header" and a "GTA replica" system.

- Similarly IMASAF in Europe offers both types of systems.

- Spruell offers a 4-into-one header that I think is what is on the car now (the one on the car is rather worn out so I want to replace it). I could get another of these, but besides the price, I don't think it offers any performance advantage over the GTA style system.

- Finally, from what I hear the Centerline system is better quality than the one IAP offers.

- Has anyone compared these various systems head to head for quality? Taking them one at a time:

- Who would you say offers the best GTA replica system?
- Who would you say offers the best system for a 2-liter race application?

Doug Bender
 

·
Supporting Vendor
Joined
·
4,406 Posts
Doug,

I hope I can clear up a few things:

The "GTA Replica" system we sell at Centerline is the IMASAF system.

It can be made to fit with a 2 liter engine with some work - you need to fit spacers to move the headers away from the block and do a little bending where the headers come out underneath the car. This is due to the fact that a 2 liter is ~2in taller than a 1600.

From the headers, you can fit either a Stradale or Corsa (side dump) exhaust.

George Willet has told me the standard Centerline Performance Headers make better power than the GTA Repro on a 2 liter.

A fellow racer on the BB is currently comparing GTA Repro and Spruell systems on the dyno and has promised me results soon, that I will of course share with all of you.

Joe
 

·
Premium Member
Joined
·
1,114 Posts
I was not impressed with quality of the IAP headers I once owned... didn't even put them on the car.
Dunno about the others.
 

·
Registered
Joined
·
1,817 Posts
Joecab, will ph109 and ph110 fit the factory header? I'm concerned about the heat the after market headers produce and I would prefer to keep the original header in place.
 

·
Registered
Joined
·
601 Posts
Discussion Starter #5
I can answer that! The GTA front section (PH109) doesn't even come close to fitting the stock cast iron manifolds. Look in the Centerline catalog at the picture marked "105/115 downpipe" on page 49. You can see that the stock system has downpipes to mate to the cast iron manifold, while headers include the down pipes.

Doug Bender
 

·
Registered
Joined
·
1,085 Posts
I recommend using the stock cast headers for the street in all applications, tube headers for the track.
 
  • Like
Reactions: 1978alfa

·
Registered
Joined
·
1,085 Posts
Exhaust header choices, and why: IMO.

It is hard to believe, but the same header works well for each of the Alfa engines; 1570, 1779, 1962cc. The reason appears to be the velocity of the exhaust, and the velocity of the gasses created by the piston speed in feet-per-minute. Each of the engines reaches volumetric efficiency at about the same piston speed. (Due to many factors: bore/stroke ratio; windage; port angles; combustion chamber shape; etc)

Of course, a lot depends on the porting of the engine, cam timing, venturi (choke) size, and so on. But for 99% of the engines built today, smaller tube sizes, IE: 1 1/2" OD, will give the best torque, and, Alfa is a torque engine! If you have ported much larger than normal, and are trying for high horsepower at the expense of torque, and are using well designed pistons in the 12.5 to 13:1 CR that purge the residue gassses from the combustion chamber,then larger (1 ¾” OD) headers appear to work in those applications

I use the Centerline headers PH 118, and modify the collector to 2 ¼” for the 1570 and 1779 engines and to 2 ½’ for the 2 liter engines, and then continue that size to the muffler. They fit the hydraulic clutch chassis with no problems, but it is necessary to extend the clutch shaft to the left to clear the headers for the mechanical clutch set-up.

Of course the original GTA headers work well on the mechanical clutch chassis, but are getting rare. None of the current after market GTA headers is the same as the original, (larger tube diameters).

We have worked this out on the dyno, (with mufflers, as nearly all the venues call for reduced sound decibels), and on the track, with different gear ratios, car weights, engine sizes, etc.

Others may have build “recipes” different than ours, and so have different thoughts. There are only a few engine builders, in my experience, that have the knowledge, money and experience to reliably turn more than 7500 rpm on a 1570, and 7/7300 rpm on the 1779/2liter engines. More exhaust diameter helps those engines, but smaller is better for us.

Remember: torque wins races, horsepower sells cars.
 

·
Registered
Joined
·
601 Posts
Discussion Starter #8
George

Couple of quick questions:

- Why do you take the catalytic converter headers (PH118) in preference to the non-cat headers (PH115)? is there a difference in the headers themselves?
- When you talk about modifying the diameter of the collector, are you talking about the part where all four tubes have converged (i.e. the "1" of 4-2-1)? How do you modify the diameter, use a pipe expander?

Doug Bender
 

·
Registered
Joined
·
1,085 Posts
Centerline Header Collector differences

The headers are the same, the collectors are different.

The PH 118 collector has a shorter length to the third wye than the other collector, by about 12"(?). The longer ones are out of the length for higher rpm tuning, while the shorter length is very close to optimum tuning.

Modifing the collector: I take the pipe (of the diameter that I will use) and squeeze it in the vise to make it oval, and to match the oval portion of the collector, (which is 2"OD; cut off the flange first, so you can slip the new diameter pipe over). After the new pipe matches the oval shape of the collector, mark the collector where the larger pipe makes contact. If done right, when you use a band saw to cut on the line, the pipes will now butt together, and you can "stich weld" the seam and now have a larger diameter exit pipe. I leave the new pipe about 6" long, and then take a length of the same diameter pipe, enlarge the end to just slip over the 6" length so it can be a slip joint, run it under the seat, mount the muffler in the stock location with two hangers to keep the muffler from twisting, and use a short down pipe, (or run a tail pipe UNDER the axle and out the rear. Even on the street. Shorten the limit straps).

I use the 2 1/2" Magnaflow mufflers, the 2 1/4" have a 2" reduced inner tube construction. They are quiet for the street and on the track, and they last.

The replica GTA headers sold all appear to be from the same fabrication company. The pipe diameter is 1 3/4" (origional GTA pipes are 1 1/2"); the pipes are welded onto the flanges so that the gasses have to make a sharp turn as they exit the port; and the last set I tried to put on a '65 GTA would not clear the pedal box/clutch linkage. The "bread and butter PH 118 are the best headers I have found; I have never had to do any port matching on them; they clear everything (except mechanical linkage); don't crack; and are a consistant high quality; not to mention a very good price; and they do an excellant job of extracting residual gasses. The pistons are generally cleaner on teardown rather than carboned on the crown.

Again, the above applies to 99% of the engines: all-out 13:1 CR/very large D shaped ports/8000 rpm is a whole different approach.
 

·
Premium Member
Joined
·
635 Posts
Alfaholics Headers/Exhaust System

Back to Doug's original question, Has anyone had experience with Alfaholics full Stainless Steel System? It appears to do away with the front resonator, and I wonder how that is for noise on the street? It is expensive, but it should be the last system you would have to buy.

Stu
 

·
Premium Member
Joined
·
201 Posts
Tube headers on GTV with 2 liter engine

Unfortunately, I ordered headers from IAP before this thread was started. And to compound my misery, I had IAP ship the headers directly to Swaintech Coatings for treatment, thereby eliminating the possibility of returning them to IAP.

As someone mentioned previously, they are not as good as Centerline's headers. (I picked IAP's because they were cheaper. I know I deserve it, but please save me the lecture. I feel dumb enough already.)

I will be specific about the problems:
1) Several of the the nuts at the mounting flanges are so close to the tubing that you can't get a socket or box wrench on it. An open end wrench is the only way. Frustration Factor: Level 3.
2) I couldn't get the 1-4 section down in there without dropping the steering drag link. Frustration Factor: Level 4.
3) On both 1-4 and 2-3 sections, the flanges were not aligned, so it was a chore getting them to slip on the studs. I got the 2-3 section forced on by myself, but it took a helper to get the 1-4 section on. Then they would not slide on up to the head, so I attempted to move the flanges on up to the head by tightening the bolts. I always prefer to use the OEM brass nuts because, being a softer material than the studs, the threads on them will fail before the threads on the studs. But it took so much torque to thread the nuts on (and move the flanges closer to the head) that it pulled the threads out of the brass nuts. So I had to use steel nuts. No big deal. At least I got the headers all the way on. Frustration Factor: Level 6.
4) But the big problem is that the flange on #1 cylinder is warped, causing an exhaust leak. Frustration Factor: Level 10. This is where I need help. What is the best (easiest) course to take? Stack multiple copper gaskets in there? Remove the 1-4 section and resurface the flange? What I don't want to do is spend a major portion of my remaining time on this planet removing and re-installing these headers trying to find out how to make them fit and seal.

I called IAP to see what they would say. I talked to James. He said that they do see a slight misalignment of the flanges from time to time as the materials cool from welding. Probably the amount of misalignent I see on the 2-3 section. But I think the 1-4 section is worse than that caused by welding and cooling. And he said he had never heard of a warped flange on an IAP header. He would have been able to exchange them for another set, but of course that is not an option because I have had mine alreaday coated.

I welcome any suggestions on how to proceed.

Thanks.

OldAlfaGuy
 

·
Registered
Joined
·
776 Posts
OldAlfaGuy said:
He said that they do see a slight misalignment of the flanges from time to time as the materials cool from welding.
OldAlfaGuy
That's nothing but defective workmanship! Why don't they weld them more carefully? Why aren't they jigged to a heatsink while welding/cooling?
 

·
Registered
Joined
·
2,457 Posts
Contact RMR in London +44(0)20 8994 0554. Chris Robinson there does a GTA manifold which is excellent. I have one on my 2000 spyder (yes it fits OK[well just]) and one on a 1600 SZ. On starting the SZ the manufold touched the upright alongside the spring. The engine is now in a Giulietta and allowance has been made for this and the manifold is back in action. Give him a call
 

·
Premium Member
Joined
·
201 Posts
Update on GTV with a 2 liter engine

I did not mean to look like I was hijacking this thread, but I felt my current situation with IAP headers fit the topic.

By reaming out the holes in the flanges with the next larger drill bit, and by truing the flanges on a belt sander, the IAP headers now fit like a dream.

I still need to drop the steering drag link to get the 1-4 section to drop in, but I don't think that is uncommon. I know that GTA headers will go in and out without doing that. But it seems to me that a GTV vintage race car I had eight or so years ago required that step to get the headers on and off. I was never sure what brand headers they were - Shankle was my guess.

OldAlfaGuy
 

·
Registered
Joined
·
148 Posts
Dear Alfisti,

I have fitted a stainless steel exhaust system on my 1966 Giulia sprint GT Veloce.

My car has a 1750 engine.

The system I fitted is from the UK 105 specialists, Alfaholics.

www.alfaholics.com

I am very pleased indeed with the system. It fitted like a well tailored glove and makes a nice sound.

The system is very well made and clears the engine and body very comfortably.

I did however spend about 7 weeks polishing the complete system!! My car has been fully restored from a bare metal strip. The polished system looks stunning especially from underneath when the car is on a garage hoist.

A photo of my engine bay with the exhaust headers is in the International Auto customers cars gallery.

see http://www.international-auto.com/fi...acid=4&naid=25

Best Regards

Targa Florio

Adelaide Australia

1966 Giulia sprint GT Veloce
 

·
Registered
Joined
·
1,198 Posts
George:

Would you happen to have the exact specs of the original GTA header. I am looking for inlet and outlet measurements as well as length and size of each pipe. After re-reading Jim K's book he has some optimal flow numbers for the headers and I wanted to compare those to the original GTA headers. Any help would be much appreciated!

The headers are the same, the collectors are different.

The PH 118 collector has a shorter length to the third wye than the other collector, by about 12"(?). The longer ones are out of the length for higher rpm tuning, while the shorter length is very close to optimum tuning.

Modifing the collector: I take the pipe (of the diameter that I will use) and squeeze it in the vise to make it oval, and to match the oval portion of the collector, (which is 2"OD; cut off the flange first, so you can slip the new diameter pipe over). After the new pipe matches the oval shape of the collector, mark the collector where the larger pipe makes contact. If done right, when you use a band saw to cut on the line, the pipes will now butt together, and you can "stich weld" the seam and now have a larger diameter exit pipe. I leave the new pipe about 6" long, and then take a length of the same diameter pipe, enlarge the end to just slip over the 6" length so it can be a slip joint, run it under the seat, mount the muffler in the stock location with two hangers to keep the muffler from twisting, and use a short down pipe, (or run a tail pipe UNDER the axle and out the rear. Even on the street. Shorten the limit straps).

I use the 2 1/2" Magnaflow mufflers, the 2 1/4" have a 2" reduced inner tube construction. They are quiet for the street and on the track, and they last.

The replica GTA headers sold all appear to be from the same fabrication company. The pipe diameter is 1 3/4" (origional GTA pipes are 1 1/2"); the pipes are welded onto the flanges so that the gasses have to make a sharp turn as they exit the port; and the last set I tried to put on a '65 GTA would not clear the pedal box/clutch linkage. The "bread and butter PH 118 are the best headers I have found; I have never had to do any port matching on them; they clear everything (except mechanical linkage); don't crack; and are a consistant high quality; not to mention a very good price; and they do an excellant job of extracting residual gasses. The pistons are generally cleaner on teardown rather than carboned on the crown.

Again, the above applies to 99% of the engines: all-out 13:1 CR/very large D shaped ports/8000 rpm is a whole different approach.
 

·
Registered
Joined
·
1,290 Posts
Doing some research for my 2L GTV street engine.
Euro cams, Motronic 10:1 pistons and some porting will be done to the head & intake manifold.
Mechanic was asking what I wanted to do for the headers.
This will be a street engine so tube headers probably aren't really needed.
Centerline's GTA headers and mid section were being considered.
I currently have the factory cast iron headers, an Abarth front section with small resonator, Centerline's Magnaflow center muffler and a stinger.
I absolutely LOVE the way it sounds and I don't want to change anything.
This conversation was helpful reading.
 
1 - 19 of 19 Posts
Top