New Header Dyno Results

[AnthonyG]

Really enjoyed coming across this old post.

Maybe we can revive and revisit it a bit.

Unless I'm mistaken, Mark's header's dramatic twist to the left is to accommodate those with an A/C compressor, and it's somewhat shorter length leaves room to accommodate a cat in addition to the muffler, if desired or necessary.

At this point, it's a rare design that I don't think is available elsewhere. A Euro 4:2 exhaust manifold, with a short Euro/Yugo 2:1 down pipe would be the next closest thing. Those are increasingly hard to source stateside, AND there would likely be some PITA fabricating to line up (or make room for) a muffler and/or cat.

As a CA guy with an 86 FI X who has to pass pretty strict smog, a better flowing performance header/exhaust WITH the option/space for a cat, that would enable me to likely still pass smog, is pretty fantastic and rare, especially 10+ years later.. I think he designed it so we wouldn't be left out, and I appreciate that.

Mark, word is you're semi-retired.. Are you still making these?

Would be great to hear from you here, and let's us know the latest.

There may be a new generation of Xers on Xweb interested in your stuff, if you're still game.

anytime you're going to compare apples to oranges and try to decide which one tastes better, the discussion will get complicated. Besides straight dollar costs, you should compare the task of doing internal engine work vs an hour for bolt-ons, short-term and long-term reliability, whether there is any cost due to operating costs.
As I mentioned earlier, I'd suggest you do both mods; an improved cylinder head and exhaust. We picked up 2 hp with a tweaked afm and cold air intake. Without the header, would the afm have provided an increase? Would Matt's head improvement net 12 or 15 more hp with our exhaust? All questions begging for answers.
Dyno testing is pretty expensive though and I'm more than satisfied with our results. We've netted a 15% hp increase and nearly 20% torque increase at an rpm that is very usable and those are unheard of numbers for a header, especially with a catalyst. Our system scavenges so well, that other modifications will be enhanced.
So the head gives 10hp and our exhaust gives 7hp but the two together might produce 20 or more. The afm tweak shows the engine likes more air and fuel, so put in some overtime and adjust the budget a little higher

 

[AnthonyG]

Came across these pages.

Would be great if Mark is still making them.

Allison's Automotive | FIAT 500, 124 & X1/9 performance

allisonsautomotive.com

Headers and Exhaust

State of the Art Header for 124 Spider and 124 Coupe The 124 header is ideal for engines that need more low end torque without sacrificing top end power. The stepper design has been proven on all Fiat twin-cam engines, from stock motors to full road-race versions, providing amazing mid-range...

allisonsautomotive.com

Search: 6 results found for "x 1/9 header"

Auto Ricambi And Allison Automotive Join Forces

allisonsautomotive.com

anytime you're going to compare apples to oranges and try to decide which one tastes better, the discussion will get complicated. Besides straight dollar costs, you should compare the task of doing internal engine work vs an hour for bolt-ons, short-term and long-term reliability, whether there is any cost due to operating costs.
As I mentioned earlier, I'd suggest you do both mods; an improved cylinder head and exhaust. We picked up 2 hp with a tweaked afm and cold air intake. Without the header, would the afm have provided an increase? Would Matt's head improvement net 12 or 15 more hp with our exhaust? All questions begging for answers.
Dyno testing is pretty expensive though and I'm more than satisfied with our results. We've netted a 15% hp increase and nearly 20% torque increase at an rpm that is very usable and those are unheard of numbers for a header, especially with a catalyst. Our system scavenges so well, that other modifications will be enhanced.
So the head gives 10hp and our exhaust gives 7hp but the two together might produce 20 or more. The afm tweak shows the engine likes more air and fuel, so put in some overtime and adjust the budget a little higher

 

[fiatfactory]

If you really want to put these results into perspective (and then they don't look quite as impressive) is to compare identical engines fitted to standard Fiat models with the only change being the exhaust manifold and front pipe... all other engine parameters i.e. compression ratio, cylinder head type / valve sizes / combustion chamber shape/ caburettor etc etc ae the same, the ONE difference being te exhaust manifold/front pipe...fortunately for us an example exists.

A 128 1300 coupe (european or australian spec) is rated to 75hp.

A 128 rally uses an absolutely identical engine, the one and only difference is that it uses a single out exhaust manifold and front pipe, even the rest of the exhaust system is the same pipe size / mufflers etc so he only difference in the two setups is the exhaust manifold and front pipe... a european 1300128 Rally is rated at 67hp

that's 8hp difference right there, no other changes.

as for the parts being hard to find, you're just not looking very hard, brand new Tipo 1600 genuine Fiat exhaust manifolds are available ex Germany for 69 euro plus shipping.

SteveC

 

[AnthonyG]

Heard!

Great stuff. I have more perspective now. Thank you!

I'm leaning towards the 4:2 exhaust manifold. Will search for a Tipo 1600.

I sent you a PM earlier.

What do you think about the Euro 1500 X1/9 exhaust manifold vs. the 1600 Tipo? The Tipo ports are a touch bigger, right?

I think you said in your "Ultimate" opus that the 1600 would just require some fabricating on the 2:1 down pipe end?

I think the lower flange on it left leaning, which matches the U.S. 1500 FI X.

From what I've read, a center flange may be problematic. Though I could be wrong.

I need to be able to fit a cat with the muffler as well (CA smog test), so I gather it could be tricky.

If you really want to put these results into perspective (and then they don't look quite as impressive) is to compare identical engines fitted to standard Fiat models with the only change being the exhaust manifold and front pipe... all other engine parameters i.e. compression ratio, cylinder head type / valve sizes / combustion chamber shape/ caburettor etc etc ae the same, the ONE difference being te exhaust manifold/front pipe...fortunately for us an example exists.

A 128 1300 coupe (european or australian spec) is rated to 75hp.

A 128 rally uses an absolutely identical engine, the one and only difference is that it uses a single out exhaust manifold and front pipe, even the rest of the exhaust system is the same pipe size / mufflers etc so he only difference in the two setups is the exhaust manifold and front pipe... a european 1300128 Rally is rated at 67hp

that's 8hp difference right there, no other changes.

as for the parts being hard to find, you're just not looking very hard, brand new Tipo 1600 genuine Fiat exhaust manifolds are available ex Germany for 69 euro plus shipping.

SteveC

 

[AnthonyG]

The few Tipo 1600s I'm finding are much more than $69.

Searched Google and Ebay with "7691880 exhaust manifold" and "Tipo 1600 exhaust manifold".

The closest I get are a few European sites that are sold out of them, and a few on Ebay, but all are listed for ~ $250 and up + $100 shipping.

I guess the market for them has spiked.

If anyone knows where to sources the $69 ones, please let me know.

 

[fiatfactory]

69.50 euro from Bielstein in Germany

Manifold

Manifold: Exaust manifold Fiat X1/9 - Bolt set Exaust manifold Fiat X1/9

www.bielstein.com

if you use the carby model muffler it positions the CC a little further to the left side of the car (the inlet to the muffler is shorter) so that may help to package the CC in there as well.

SteveC

 

[AnthonyG]

Ahhhh! This is the Euro 1500 model (#4392487). I was searching for the Tipo 1600 (#7691880).

But this is just fine with me!

From what I've gathered, They're nearly the same --the Tipo having just slightly wider ports.

This is great! Thank you!

Next I gotta figure out what to use for the 2:1 down pipe (and it's length and direction) (maybe the Yugo?), and how fit and run both the cat and muffler.

I think I understand what you're suggesting with the shorter muffler inlet.

It will probably help when I can see/visualize it.

Thanks for the responses, Steve. Appreciated!

69.50 euro from Bielstein in Germany

Manifold

Manifold: Exaust manifold Fiat X1/9 - Bolt set Exaust manifold Fiat X1/9

www.bielstein.com

if you use the carby model muffler it positions the CC a little further to the left side of the car (the inlet to the muffler is shorter) so that may help to package the CC in there as well.

SteveC

 

[AnthonyG]

Carb 1500 muffler (short inlet tube = more room for cat and 2:1 down pipe):

FI 1500 muffler (longer inlet tube = less room for cat and 2:1 down pipe by a few inches):

Yugo 2:1 down pipe:

 

[fiatfactory]

No, that's a 7691880 tipo exhaust manifold shown in the Bielstein picture...

SteveC

 

[AnthonyG]

No, that's a 7691880 tipo exhaust manifold shown in the Bielstein picture...

SteveC

Hmm. The description and the photo don’t match. That’s why it didn’t turn up when I searched for it. Description says part #4392487, 1500 Carb X1/9. Guess I’ll have to ask them which one they’re selling.

 

[Dr.Jeff]

First let me define how I use certain terms. The "manifold" is only the part that bolts to the head. The "downpipe" is the section that begins at the manifold and drops down toward the rear area where the muffler and remaining system exist. Exactly where that point is can vary a lot. The "exhaust system" is the pipes, muffler, cat, tip, and anything else beyond the downpipe.

For the most part, the ability to include a cat in the exhaust is not really determined by the manifold itself. But by the downpipe and exhaust system. Pretty much any manifold can utilize a cat, as the cat is a part of the exhaust system beyond the manifold. And the position of the manifold outlet (left, center, or right) will not make any difference. The location of where the downpipe ends and how the rest of the system is designed will. To be clear I am not referring to any of the stock factory exhaust systems, they are not worth using due to their excessive weight and restrictive design.

I think the best approach for using any of the Fiat cast iron dual-outlet manifolds is to custom fabricate the downpipe and the exhaust system. There really isn't any existing downpipe that will directly mate any factory manifold and a decent cat/exhaust system. And starting with any of the existing downpipes leaves little to be desired in terms of optimal dimensions. So making one from scratch (either yourself or have a muffler shop do it) will allow a better design and the ability to include a cat and any muffler you prefer. Same for the rest of the exhaust system, a custom fabricated one will allow for better packaging, design, performance, sound and appearance.

Several have reported problems with the aftermarket header you mentioned earlier. Mostly clearance issues. And although shipping a cast iron manifold from Europe is quite expensive, it is still considerably less than that header. Between those two options I'd agree with Steve and go with a factory cast iron manifold. Less prone to leaks and cracks, more durable, better heat and noise control, and better fitting, but it is heavier. Speaking of the factory manifolds, are you sure about the tipo one having larger ports? I don't recall reading that before.

 

[AnthonyG]

Thanks, Dr. J. I agree with all you said, now that I'm connecting all the dots.

I believe the Tipo 1600 (#7691880) has slightly larger openings than the Euro carb 1500 X1/9 (#4392487), but only by a millimeter or two. There are several post mentioning the differences between them. I'll see if I can find them again.

Here we go:

X1/9 exhaust manifold differences

A couple of recent threads here have once again raised the questions of the various exhaust manifolds available for our engines. It seems info here is quite scattered and at times incorrect. Thought I would try to do some research and consolidate it into one thread. Special thanks to Andrew...

xwebforums.com

Here in Australia the 128 coupe manifold is a good choice, even better is the 1500 x19 manifold as the ports are a little larger, then there is the regata 1500 85s manifold that can work well but it has a threaded hole to blank off (or use for an O2 or A/F sensor). The Yugo 4 into 2 manifold is similar to this with a threaded fitting cast into it. Similar to these would be the 1974 X19 manifold. The most easily and current twin out manifold suits Fiat Punto , Tipo 1.6 litre variants, this has the largest port size and noticeably larger holes at the manifold outlet. These are all very similar but the offset between the head and the outlet is a little different, though if your fabricating your own front pipe this isn't a big deal.

Ultimate SOHC engine.

Fiat SOHC Performance Tuning. 1. Introduction. Despite having very humble origins as a power-plant for the 1969 front drive revolution Fiat 128, in my opinion the SOHC is quite a spectacular engine and Aurelio Lampredi's finest mass produced work. Notwithstanding it's 'inferior' design non...

xwebforums.com

I haven't done much research yet on exhaust tuning for a FI street car to maintain low-mid range torque, but so far I'm getting the impression some length in the 2:1 down pipe (AKA front pipe) is desirable, so Steve's recommendation in the "Exhaust" section of his "Ultimate" post, to run the 2:1 down pipe low and then 90 degrees left (and in MY case squeeze in a cat there), then up 180 degrees up on the left and turning right into a muffler, in much the way the stock cat and muffler are arranged, would logically be the most efficient solution.

But I have more studying to do.

The down pipe from a 128 could work with a OE muffler, but I doubt I'd be able to squeeze in the cat where the flex tube is in Steve's examples below. And I take your point about going full custom anyway.

Euro twin exhaust manifold wanted

in the recent thread on Performance Head options, SteveC commented that changing to the euro four into two manifold is a great way to improve performance and gain about 8 hp. Anyone have one they want to part with? Know where to find one? Are they the same as the US ‘74 exhaust manifold?

xwebforums.com

Converting: Cali Carb Exhaust to 4-2 manifold

Greeting all, My next project consists of converting my original California emissions style exhaust to something using the 4-2 manifold. My car came with a 4-1 manifold, cat, and muffler. I have since replaced the cat and would actually like to keep it (tree hugger at heart). I purchased a 4-2...

xwebforums.com

 

[kmead]

You might consider coming down with the down pipe and turn to the right, then 180 to the cat and then into the OE FI muffler or the carb muffler to gain the extra room. The carb muffler would like require a different version of the mount to reach a few inches to the left.

 

[AnthonyG]

So Karl.. I think Dom tried to do that and had trouble making it work..

Custom Exhaust

Hi all, I'm attempting to build a semi-custom exhaust with stick parts. My idea is to use a 4:2 manifold off a European car and somehow get it connected into a standard FI exhaust system (retaining the cat!). Here is what I have so far: The manifold (as stated) is simply a 1500...

xwebforums.com

But theoretically.. I could use a 128 2:1 down pipe, shape it (possible?), OR just use the flange and fabricate a whole new 2:1 pipe, to take the place of the stock single pipe, and run it to the stock FI cat and muffler as the absolutely "poorest man's" performance exhaust until doing a custom cat and muffler upgrade later.

If I turn right from the 2:1, then immediately 180 back left, you think I'd have enough room to match it / fit it to the stock cat?

Hmmm.


Stock FI 1500 exhaust:

Stock FI 1500 downpipe:

128 2:1 downpipe:

You might consider coming down with the down pipe and turn to the right, then 180 to the cat and then into the OE FI muffler or the carb muffler to gain the extra room. The carb muffler would like require a different version of the mount to reach a few inches to the left.

 

[Dr.Jeff]

Unfortunately the 128 downpipe will be too long to do that. Remember it is for a FWD car so they could make the runners longer for more torque (good, but won't fit the X). However you could make a downpipe to do exactly what you describe - to utilize the stock exhaust. Depending on which cast iron manifold you end up with, the actual position of the outlet (flange with dual openings) will differ. So the downpipe will need to connect from wherever that is to wherever the FI inlet pipe is. That will end up shorter than is ideal (for the secondary tubes), but can still be made much longer than the Yugo downpipe. Also keep in mind some of the exhaust systems go through the rear firewall over the crossmember while others go under the crossmember. That puts everything in a different place.

 

[Dr.Jeff]

Just a quick sketch why the 128 downpipe is too long. Not accurate nor to scale, but trying to explain the point:

 

[AnthonyG]

Gotchya. I do understand that the pipe's too long as is.

I was thinking of the 128 pipe primary for convenience of the flange on the top end and the taper on the other. And then cutting however much I'd need to out of the middle and rewelding it there, and then shaping it. Then I'd just have to add a flange to bottom end to meet the cat.

This is assuming of course 1) it could even be shaped that much (by a pro, not me), and 2) I could source one at a price that would make it sensible to do that rather than just start from scratch with all new tubing components.

If I could hand the 128 pipe to someone and tell them to do that, then I'd only have to source the lower flange to connect to the cat.

But yeah, I may be over complicating it.

Maybe I just show a picture of the 128 tube, and say "make me a 2:1 pipe like this one with flanges that runs from the manifold to the cat".

One the plus side, if I cold do that somewhat cheaply, seems like I would be set up nicely for upgrading the cat and muffler pretty much right in their stock positions in the future.

 

[fiatfactory]

Tipo (7691880) manifold sets the outlet flange a little further across to the transmission side of the car than the X19 1500 manifold (4392487) but only by a few mm.

If you put a std 128 coupe front pipe into the car with an X19 1500 or a 128 coupe / X19 1300 exhaust manifold attached, the pipe will clear all the bodywork, if you use a Tipo manifold the standard 128 downpipe will foul against the engine cross-member, like so

and that's without the manifold flange nuts done up tight, it's hard against the cross member

A front pipe from a Tipo on the other hand, routes a little differently, and the front pipe positions itself much further to the right of the car, like so... you can see the folded over lip on the transverse piece of bodywork.... that's where the standard single front pipe passes thru the bodywork.

Anthony... don't overthink this. Sure you can spend days and weeks thinking and talking about the "best" theoretical pipe sizes and lengths, but the bottom line will always be what will fit, and for a lot of people what will fit easily. Buy an exhaust manifold, take it to a good exhaust shop and have them make a part that fits the car.

Plus you need to remember how much gain you're thinking about overall, it's a small percentage compared to the numbers possible if you "built" an engine with only performance in mind.... honestly, going from 75hp at the flywheel to anywhere south of 100 hp at the crank then the stock large suspended on springs muffler will work just fine. If you were aiming for 100hp at the wheels then it's a different story and the stock muffler simply wont allow the engine to move enough air thru it quickly enough...but you're not aiming there... so be realistic.

These days cat convertors are much more efficient and smaller than something from the 1980's, some able to offer almost no drop in performance, so I would be thinking a new cat long before I thought about a new muffler... the muffler will not be a restriction to performance up to around the 100 crank hp mark, which is the very most you're likely to get with any mods you're likely to do and retain the stock ignition/EFI

SteveC

 

[Dr.Jeff]

Gotchya. I do understand that the pipe's too long as is.

I was thinking of the 128 pipe primary for convenience of the flange on the top end and the taper on the other. And then cutting however much I'd need to out of the middle and rewelding it there, and then shaping it. Then I'd just have to add a flange to bottom end to meet the cat.

This is assuming of course 1) it could even be shaped that much (by a pro, not me), and 2) I could source one at a price that would make it sensible to do that rather than just start from scratch with all new tubing components.

If I could hand the 128 pipe to someone and tell them to do that, then I'd only have to source the lower flange to connect to the cat.

But yeah, I may be over complicating it.

Maybe I just show a picture of the 128 tube, and say "make me a 2:1 pipe like this one with flanges that runs from the manifold to the cat".

One the plus side, if I cold do that somewhat cheaply, seems like I would be set up nicely for upgrading the cat and muffler pretty much right in their stock positions in the future.

That's true, it would help in building a custom fitted one. The flange at the top (that mates to the manifold) might even be worth it, provided the 128 part has the proper diameter ports and pipes (I don't recall if it does). And that's if you can find one at a decent price; I haven't looked so not sure how common they are or at what cost. I have a feeling you might do as well with everything mounted on the car and taking it to a shop to have it made. The "Y" merge at the bottom is very common and easy to get in any size. As are the pipes. It will just be a matter of getting the flanges made. If you are going to start with a stock exhaust system, the lower flange from the old one could be repurposed:

If you take the gasket for the Euro manifold to a shop that has a waterjet or laser cutter they can scan it and make the upper flange.

 

[Dr.Jeff]

Tipo (7691880) manifold sets the outlet flange a little further across to the transmission side of the car than the X19 1500 manifold (4392487) but only by a few mm.

If you put a std 128 coupe front pipe into the car with an X19 1500 or a 128 coupe / X19 1300 exhaust manifold attached, the pipe will clear all the bodywork, if you use a Tipo manifold the standard 128 downpipe will foul against the engine cross-member, like so
View attachment 53089
View attachment 53090
and that's without the manifold flange nuts done up tight, it's hard against the cross member

A front pipe from a Tipo on the other hand, routes a little differently, and the front pipe positions itself much further to the right of the car, like so... you can see the folded over lip on the transverse piece of bodywork.... that's where the standard single front pipe passes thru the bodywork.

View attachment 53091
Anthony... don't overthink this. Sure you can spend days and weeks thinking and talking about the "best" theoretical pipe sizes and lengths, but the bottom line will always be what will fit, and for a lot of people what will fit easily. Buy an exhaust manifold, take it to a good exhaust shop and have them make a part that fits the car.

Plus you need to remember how much gain you're thinking about overall, it's a small percentage compared to the numbers possible if you "built" an engine with only performance in mind.... honestly, going from 75hp at the flywheel to anywhere south of 100 hp at the crank then the stock large suspended on springs muffler will work just fine. If you were aiming for 100hp at the wheels then it's a different story and the stock muffler simply wont allow the engine to move enough air thru it quickly enough...but you're not aiming there... so be realistic.

These days cat convertors are much more efficient and smaller than something from the 1980's, some able to offer almost no drop in performance, so I would be thinking a new cat long before I thought about a new muffler... the muffler will not be a restriction to performance up to around the 100 crank hp mark, which is the very most you're likely to get with any mods you're likely to do and retain the stock ignition/EFI

SteveC

Steve, how do the diameters of the 128 or Tipo downpipes compare to the outlet diameters of the Euro 1500 manifold?


Anthony, this pic shows the location of the stock system as Steve said. That is where the FI exhaust is located. You can see how different it is from the downpipes that go under the cross member, like in this pic:

So that is where the pipes will need to mate up if you use the stock exhaust.