328/TUBI/TESTPIPE

none.

 

Maybe no Horse power gain but a donkey or two

 

Not much HP but your car will sound better, run cooler, and love you for getting that effing cat off from around its neck.

 

I put a Stebro and test pipe on my Mondial 3.2, and it feels like 25 or 30 more HP. I know I will get blasted for that estimate, but it feels that much different. (By the way, there were no other changes made at the same time; no tune up, no new air filter, no new injectors, etc.) The car is significantly faster now w/ 2 aboard than it used to be with only me driving. Scoff if you will, but I would do it!@

 

Good to hear you had that experience David. I also put a stebro and test pipe on my mondi 3.2 and the butt dyno tells me it made absolutely no difference. However, great to get the cat out of the engine bay - running temps seem to be down meaningfully.

 

"I put a Stebro and test pipe on my Mondial 3.2, and it feels like 25 or 30 more HP."

"The car is significantly faster now w/ 2 aboard than it used to be with only me driving."

It is impossible for an exhaust test pipe to add more than an HP or two over a modern Cat in an engine in this power range - if that. Now IF your cat was clogged/rotted and restricting the exhaust, THEN you would get BACK the hP that was lost by the bad cat. SO perhaps there was a major improvement but if so, it was because there was a problem with the old cat.

Recently John Lingenfelter (noted hi performance chevy guru) conducted dyno tests on one of his 700+ RWHP engines and found that removing the cats and installing straight pipes added up to 9 HP and even at that he noted that there were inconsistencies from run to run within the error of the dyno itself at that HP level so that he could not be sure that the 9HP was really there. So basically there is really nothing to be gained performance-wise on these cars by removing a cat that is in good condition. Removing them for other reasons - perceived fire hazard, etc is a different issue.

Frankly, I think there ought to be an informal internet law against stating engine power increases without some sort of measured data to support it!

 

Without making ay other changes your top Ferrari tuner is correct, at almost 2 HP.

 

no increase in power without tuning

as you decrease restriction or increase exhaust volume, you will also need to retune the engine or you will lose back pressure and lose useable power in the midrange where you need it most. the car will feel slower and you'll have to give the car more gas in part throttle situations
re tune the vehicle and you willl see/feel the increases in power to support the mod.

 

After reading all of these comments, I am almost willing to conclude that I had a stuffed up cat and that's why I noticed a large increase in power and driveability.

 

magic

probably less heat as well

 

Just a question...a Euro 328 puts out 270 hp while the US 260. From what I understood it is because of emission requirement on the US version. If the latter is right, it just makes sense that "unrestricting" the exhaust (plus tuning) should achieve that 10-horsepower gain, right? If not, why? Any other factors for the 10-hp difference?

Ron

 

Compression was a little higher on the Euro cars as well..Pistons are different for US version vs Euro

 

The compression (as I've just recently learned) is higher on the euro; there is an actual "dual exhaust" instead of both headers feeding to a single pipe/cat; and the timing is advanced over the US version. So there's the 10 hp.

The compression change is worth around 4 HP and it's reasonable to assume that the timing and exhaust could manage another 6 between them - I'd tend to think the timing would be worth more than the exhaust difference but whatever. The timing is easy to set to Euro specs but the other two are way too expensive to bother with for such a minimal HP gain unless you are already into the engine for other reasons. A supercharger would be a far easier and waaaay more effective method to boost HP.

Interestingly, even though the euro has more power, European road tests I read did not produce acceleration figures comparable to US road tests. As an example, I saw road test from Europe that showed a 1/4 mile time of 15 and change; Car and Driver managed a 14.2. That's a really big difference and I assume that the Euro tester(s) treated the car with kid gloves while C&D drove it like they stole it!

 

Thanks, Maurice and Mike. Makes sense.

 

And while we're at it,there is the weigh difference.When I was buying my car I was able to test back to back my Euro car against a local Aussie car which I believe to be based on US spec,,well it had cats as well as the flagship mirrors.Anyway I felt a noticeable seat of the pants difference.I dont know if it was the 10hp difference,the weight difference or the other car wasn't tuned as well(although it didn't have any apparent stumble).

 

You and your friend should have just put ''em side by side and WOTted them! Then there wouldn't be any speculation about which one "felt" faster; one of them would have been in front at the next stoplight, telephone pole, road sign, cactus, whatever!"

 

I lived with a test pipe in front of my Tubi for about 5 years. Unless you are dead on with the CO (and even a little if you are not) you may find a really strong exhaust odor that's too much to deal with long term.

The answer is a Hyperflow cat. I cannot tell a single bit of performance difference between one of those or a straight pipe but it will eliminate the stink.

Just something to keep in mind.

 

Just running cooler and not worrying about dumping fuel in the cats is all the reason to get a test pipe. Plus it sounds so much better!

Ace

 

No HP increase, but a little cooler running.

 

Anybody have a sound clip of stock exhaust plus Hyperflow cat? Does it resonate at highway speeds?

 

Mike sorry maybe I wasnt clear in my post..The place where I bought the car from had both cars and I was able to test them in that way one after another.I chose the one I got based on a few minor things as well.Mileage was 17k on the euro and about 55k on the local delivered car.The mirrors was something I really disliked about the local car as well.

 

I put a hyperflow cat on my 328, replacing the oem Cat. If there was any difference in the sound, I couldn't tell when driving the car. Note re that - I looked carefully at the oem Cat after removing it - it appears to have more flow-area than the hyperflow does just by looking through it. The cat area is much larger so frankly it is my opinion that an oem cat in good condition will flow as well (maybe better) as the HF cat.

I replaced the orem just based on it's age but had I pulled the oem first and looked at it (a much smarter method), I would have saved the money and left the oem in place. OTOH the HF is shiny and weighs less!

 

Tommy cosgrove is right, the Hyperflow will eliminate the odours but there is not much HP to be gained. Your engine will run cooler, with better scavenging of exhaust gases you may gain 2-4HP but not more than that.

I'm attaching a sound clip of my 308 with Hyperflow and Stebro exhaust (with tips in).
Image Unavailable, Please Login

 

" Your engine will run cooler, with better scavenging of exhaust gases you may gain 2-4HP but not more than that."

I would not expect any of that unless your existing cat is clogged.