Dyno results on the 328

Hi All,

We have a very unique opportunity here at Fabspeed, as we have in house right now 4 generations of Ferrari 300 series cars. The latest to come in is a 328 GTS, owned by John R who is a contributor here on F-Chat. John responded to my earlier thread where we were looking for a 328 car for development.

The first results I have to share with you all are the power gains from installation of one of our 200 Cell Sport Catalytic converters. This is a great upgrade for those who wish to keep the stock mufflers, but want a little more sound and performance. We saw gains of over 10hp to the rear wheels with the installation of the Fabspeed 200 cell catalytic converter, with gains across the entire rpm band. Torque was up 8 ft. lbs through most of the rpm range, with a gain of 6 at the torque peak.

Next up is testing of a rear muffler system that will hopefully increase power a little more. We are toying with the idea of a valved muffler - quiet for cruising and loud when you want it to be. Having a 328 and a 348 for development at the same time is really great, since I get to see how the changes Ferrari made between series translates in what type of exhaust setup each car is happiest with.

Below are some preliminary dyno results:
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Nice! I have your HFC+xpipe on my e92 m3 and am very pleased with it. I have a tubi waiting to go on the 308 though : )

Good luck with your development! Great to see this kind of work and innovation taking place in PA!

 

Thank you for the work you folks do!!

I love the updates on things like this.



PDG

sent from Io, innermost moon of Jupiter

 

Chris, Let me know when you want to do some dev on a 79 carb 308.

Bob

 

Any video of the Dyno runs for sound comparisons?

 

Chris this is a great thread, awesome work.

I have a straight pipe set up that came with my old black 328 that was squashed and totaled.

I swear when I slip this straight pipe on my current 86 328, the car gains power and a lot of throttle response. Some places need cats, everyone has to have mufflers for the street.

Why would a straight pipe add more power than a muffler? Back pressure?

Thank you. Awesome work. Great thread.

 

Mufflers get a lot of grief that they don't deserve re power. A muffler can be quiet and have virtually no effect on power and a muffler can be loud and reduce power. I have seen/dynoed both. One of the most popular mufflers around for performance use - one that you can look through from one end to the other, actually reduced power compared to a stock muffler.

It's all about the design of the muffler and the specific characteristics of the engine. A muffler that works well on one engine can subtract power on another.

It's actually easy to make a very quiet muffler with no adverse affect on power. The problem is…it needs to be large. Modern motorcycles are doing this quite well - 200HP sport bikes are rather quiet because the mufflers are quite large. People assume a small, loud muffler makes more power but there is no direct correlation; louder, in itself, is not faster. Many of the HD motorcycles you see on the road have been modified with straight pipes in lieu of muffs and many of them are making less power than they were with the oem mufflers. (I'd say "all" of them but surely a few actually have straight pipes of the correct length for the engine)

"back pressure" is a term that is often misused. Yes, a clogged system could be described as having "back pressure" but the actual property that affects exhaust tuning, and which is often called back pressure, is the reversion wave. All systems have a reversion wave; it can be used or misused. The frequency of the wave determines whether it will enhance or de-enhance power. Any exhaust system has a reversion wave (as does an intake system). How this wave interacts with the engine affects power output.

The mufflers that I referred to earlier, the ones you could see through and that reduce power, were/are typically described as having no back pressure. How can they have back pressure, you can see right through them? The problem is two-fold - their reversion wave characteristics do not compliment the engine AND their pipe design creates a lot of turbulence which actually impedes the exhaust flow.

We dynode one of the mufflers I am referring to on a 350HP us V8 and LOST HP compared to the stock mufflers on the car. Yet the company making the muffler showed a 13 HP increase for the same engine in their ads for the muffler in the popular magazines at the time. How'd they get away with such false advertising? Simple, they compared their muffler with a clapped out/rusted oem muffler and got the 13 HP gain. The ad said something like, "replace your old muffler with our XYZ and feel the power!" So they weren't exactly lying, but they weren't exactly truthin' either... a new oem muffler got nearly 20HP over the clapped out muff! They simply left that part out…

How do I know? I was one of the dyno testers for the ads…

There is a lot more to making a useful exhaust system than is often realized and just because a new system is loud doesn't mean you are getting more power than stock; it could mean the opposite.

The above is JUST an explanation and some personal experience. Do not take it as any sort of question re Fabspeed. I worked with Joe at Fabspeed in 2000-2002 on their Porsche 996 mufflers, their air box, and their add-on computer system. The mufflers and computer added 27 HP to my 996 - I was present for all the dyno testing and subsequent road testing with laptop tweaking of the add-on computer done while driving the car at speeds/loads from idle in traffic to WOT acceleration up to 130+ mph.

 

You guys started out with a pretty strong 328 going in. Most I've seen dyno at around 215 at the wheels. Good stuff, glad someone is doing this sort of thing for these cars.

 

Awesome post.

 

This 328 has had the heads off for a head gasket replacement, so I am assuming it is either the non-factory valve job, the shaved heads, or both, that give this car the stronger numbers.

Later today I will be dyno'ing a muffler delete pipe, not for sound, but this will tell me if the 328 engine likes virtually no backpressure at all - this will help me in my design direction for the valved rear muffler setup we will go with.

 

"but this will tell me if the 328 engine likes virtually no backpressure at all "

Essentially the pipe acts as a collector extension (whether it's a Cat or a pipe) and the length/volume of that pipe determines how the reversion wave affects cylinder evacuation. You can change the torque/power characteristics on any fixed-management engine by changing the collector length. Modern engines are able to adjust cam timing, intake volume, and exhaust volume to suit the RPM range which is why they can make much more power - they can optimize everything throughout the engine's RPM range. Old engines - like ours - have to rely on tuning the engine for max power in a specific, limited RPM range or, reduced power/better response in a wide range (better for street use).

It is possible to actually pull fuel/air right out out of the cylinder before it is burned if the reversion wave is 180-out with what you want. Mopar Hemis were (are) well know for their ability to do that with mismanaged mods with wrong cams/header design/intake systems, etc.

 

Yes this is what I want to test. I know the cam specs of the 328 engine and judging by the amount of valve overlap and the high redline of the engine, I think a free flow exhaust with little backpressure is what the USA F105 engine will like for best mid range and top end power. We can control low rpm cylinder filling with the valve planned for the exhaust.

 

GREAT post...I have been thinking about going with a euro header system (true dual exhaust) with the twin cats...or maybe just test pipes just to get away from the factory single cat the 328 currently has..
Have You done any testing on the dual (Euro w/cats) vs the single w/cat set up?

 

My 86 328 has a test pipe and a polished Tubi. Its too quiet and raspy for me. I intend to get a Magnaflow set up made for the car. I ran the straight pipe and test pie briefly. Its " a bit" loud, but not loud enough for LEO's to bother me about it. No idea what the big to-do is over Tubi mufflers. This is the second Ferrari I have had with one and they do not sound that great.

The car pulls harder and has way better throttle response with the straight pipe and a K&N filter. But its too loud to drive around all the time with it, so a tuned muffler would be ideal, which is what Chris is going for I think.

 

The stock US headers are plenty good for power. The restriction on US 328's comes from the exhaust after the headers - the US cats and rear muffler.

Today I tested a muffler bypass pipe, coming off the 200 cell sport cat, and picked up an additional 12rwhp! I have the 328 making 243rwhp, which is +21hp over stock! The gains are across the entire torque curve as well. See the below dyno chart.
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Interesting. What does this setup look like?

 

Are those two curves from the same car/engine? I'm curious about the difference in the cutoff portion of the power curve - which is so abrupt that it appears to be the rev limiter cutting in but there wouldn't be any difference in the rev limiter cutoff on the same engine.

I deleted what was here previously regarding the curves not crossing at the correct spot (5200 RPM) - it was totally my error in reading the dyno chart on my iPad because the display was rather small. I see on my computer that the curves are as they should be. I apologize for any confusion that may have occurred for those who may have read the post prior to my deleting the erroneous part.

Still wonder about the sigh-off rpm difference of the two runs

 

Very cool! Did you do a run with no cat and just a test pipe and muffler bypass pipe?

Great thread. How much are the muffler bypass pipes going to cost?

 

the 328 had a single cat, shared with the TR. a bypass pipe would be about the easiest thing to make. it's the goofy single in muffler that needs to go, the euro version is twin in.

 

Just a simple 90 degree bend off the cat. 2.5" tubing.
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The power curve is typical of dynojet operation. I could eliminate the dip at the end if I pushed the green "stop run record" before I let off the gas. Same exact car is being used. The Ferrari tach is a little off and I don't want to bounce the thing off the rev limiter, so that is why the graphs do not end in the exact same spot, however I am stopping the run hundreds of rpm's after peak power, so whether I go to 7400 or 7700, I don't really care.

 

I am not sure that we plan to offer just a muffler bypass pipe - in order for us to build a product we must build a fixture for it, and I don't see the demand for something like this. It doesn't sound good until above 5500. Ironically the drone isn't bad at all (with the sport cat installed). It's loud and farty sounding below 5500 though.

The purpose of the dyno was to give a design direction for the rear exhaust we plan to offer.

 

"it's the goofy single in muffler that needs to go, the euro version is twin in."

If that is the difference re HP between US/Euro, there would be a lot more than 10 HP difference between the euro/US 328. Some of that 10 HP is timing since the Euro has a more advanced curve.

But, of course, the design of the oem euro exhaust could add a bit of HP at top RPM due to the (apparent) increased volume of the system. There is nothing inherently bad about a single exhaust system and a properly designed single can produce the same HP as a properly designed dual - current motorcycles are doing this with great results. However, WHETHER either of the Ferrari 328 exh systems (US or Euro) are optimally designed, I have no idea. Based on the info Chris has posted, It appears neither of them are very good as far as power is concerned but whether they could make good power AND meet noise/emission requirements was the issue for the factory. There's not much room for large muffs/cats in a 3x8 which can be both quiet and powerful...

The only caution I would advise re the testing showing increased power based on exh changes is to be sure that the ONLY changes to the car are whatever exhaust changes. Of course, Fabspeed might want to further investigate work re ignition/fueling but that's much more involved on these cars as opposed to just bolting on exh parts.

Definitely interesting stuff though I have to admit it seems like an awful lot of lost factory HP if there really is a 21HP improvement with just an exh system mod. Makes me wonder about Ferrari's R&D - at least for their street cars. The Fabspeed data would seem to show that the factory made no attempt at all to REALLY design a decent exhaust (for Euro or US), they just stuck some stuff on there that would do the noise/emissions job. Either that of their just wasn't space to accommodate a system that could provide the power AND meet the other requirements.

"however I am stopping the run hundreds of rpm's after peak power, so whether I go to 7400 or 7700, I don't really care."

Right, gotcha! No need to run to that RPM power-wise. I was just curious since they were different. Thanks Chris!

 

Thought I'd add this

Since I was involved in some of the earliest Fabspeed products - Porsche 996 mufflers/computers/airboxes, I'll be very interested in whatever they come up with for the 328..

However, whether I will be able to afford a Ferrari system is a different issue! Chris, will be you offering the identical system for a "Fiat?"

 

Alex Traverso was telling me that back when he was tuning a bunch of spec racers (348s, IIRC), he researched the timing issue and settled on a 6-degree advance (IIRC) which accounted for a big wallop of HP gain (I think he said 30 rwhp). Can't remember if this was the euro-spec, or slightly more advanced than that. He was suggested that as something to consider for some "free" hp at the next major. Of course, once you go there, youi need gas with more octane than is available here in AZ to prevent predetonation.