purpose of C1 exhaust crossover pipes

[William F.]

Someone in past replaced exhaust system on my '62 340 hp without the crossover pipes that should be on this car's exhaust. What is their purpose? I have read they give a better sound to a FI car due to no side to side connection of fuelie intake runners, but what about cars with carbs? Do they improve performance? Lower backpressure??
Thanks

[William C.]

Re: purpose of C1 exhaust crossover pipes

Yes and Yes.

[Steven B.]

Re: purpose of C1 exhaust crossover pipes

Mr. Clupper is correct. Crossovers, "H" or "X" design, increase scavenging, balance exhaust pressure between the two sides, increase torque at low and mid range on most designs, and minimize pulsing. Looking at the firing pattern of V-8's you can see how the imbalance occurs and a crossover device is of value. Crossovers benefit all indiction types and does add to the sound, too.

Steve

[Tom P.]

Re: purpose of C1 exhaust crossover pipes

Soooooooooooooooooooo, if that's the case, then beginning with 63-later models, why was there no crossover on any engine (Vette, pass car, whatever)? Plus, none of the other V8 powered cars used a crossover, regardless of GM, Ford, Mopar, etc, etc.

[Joe M.]

Re: purpose of C1 exhaust crossover pipes

The 1961 GM P&A book shows that 2 GM vehicles had crossover pipes: 57 passenger car with dual 4BC and FI, 58 passenger car with 283 or 348 and dual exhaust

[Steven B.]

Re: purpose of C1 exhaust crossover pipes

Soooooooooooooooooooo, if that's the case, then beginning with 63-later models, why was there no crossover on any engine (Vette, pass car, whatever)? Plus, none of the other V8 powered cars used a crossover, regardless of GM, Ford, Mopar, etc, etc.

Dunno Tom. Maybe cost, parts and assembly standardization, didn't return the performance worth the cost or effort, or---???

[Stuart F.]

Re: purpose of C1 exhaust crossover pipes

As I recall, the exhaust sound was less with the cross over, specially if you had glass packs or smitty's.

Stu fox

[Steven B.]

Re: purpose of C1 exhaust crossover pipes

W

As I recall, the exhaust sound was less with the cross over, specially if you had glass packs or smitty's.

Stu fox

Stu, when I added the crossover to my 283 I noticed a little quieter and little deeper tone. Once in awhile I just pull the factory round mufflers off for "old times sake". I never had anything but the factory round mufflers on it but a fellow I knew who had a '57 327 with dual AFB's and Cherry Bombs used to make it scream at 6500+ and then back off with a beautiful popping. Steve

[William F.]

Re: purpose of C1 exhaust crossover pipes

Thanks to thr replys to my questions. To stir the pot a little, a friend of mine who keeps up with such things says that current opinion is that crossovers don't help performance. Anything to this?

[John H.]

Re: purpose of C1 exhaust crossover pipes

Thanks to thr replys to my questions. To stir the pot a little, a friend of mine who keeps up with such things says that current opinion is that crossovers don't help performance. Anything to this?

William -

If you'll do a search in the archives, look for this thread:

Title: "Re: 290 HP FI car exhaust crosstie pipe", posted by Duke Williams #22045 on Thursday, 7 June, 2001, at 12:16 PM. It's the best one-page explanation of the benefits of the crossover pipe you're likely to find anywhere.

[William C.]

Re: purpose of C1 exhaust crossover pipes

And Like John, having worked for GM for a number of years and lived with guys who worked in "CEC" (Chevrolet Engineering Center) I would have serious reservations about a claim that that there was "no benefit" to anything performance related that Chevy spent money on.

[William F.]

Re: purpose of C1 exhaust crossover pipes

Why did Chevy quit installing crossover pipe on hiperf engines from mid 60's on if there was a benefit? What I'm talking about is while crossover pipes have been advised and used on hiperf engines, Chevy and others, some say thinking has recently changed and are no longer recommending crossover pipe as a performance enhancer. Anything to it?

[William C.]

Re: purpose of C1 exhaust crossover pipes

For one thing, today at least at the oem level, you have to contend with Cat converters, which as one of my co-workers explained when they were first designed "is like putting a cork into the exhaust pipe" The option of the 2 1/2 inch exhaust system on the midyears would also have reduced the need for the crossover in normal applications.

[Duke W.]

Re: purpose of C1 exhaust crossover pipes

William -

If you'll do a search in the archives, look for this thread:

Title: "Re: 290 HP FI car exhaust crosstie pipe", posted by Duke Williams #22045 on Thursday, 7 June, 2001, at 12:16 PM. It's the best one-page explanation of the benefits of the crossover pipe you're likely to find anywhere.

I was going to copy and paste that response here, but I couldn't find it.

All modern Corvettes going back at least as far as the first C5 have crossover pipes. I think the C4s also have one in the form of a center resonator that allows co-mingling of exhaust pressure waves and flow from both banks.

The crossover pipe primarily benefits sound quality because both sides of the exhaust have eight evenly spaced primary pulses rather than four unevenly spaced primary pulses. The higher frequency is considered more pleasant to the human ear. That's why Formula 1 engines sound better than lawnmower engines.

And since flow in separate pipes is non-steady, a crossover effectively reduces backpressure by providing two flow paths for cylinders that exhaust only 90 degrees apart. Cross over pipes are less common on flat crank V8s where each bank exhausts at equal 180 degree intervals, so there is no interference between two cylinders firing 90 degrees apart on each bank as is the case with cruciform crank V8s.

The elimination of the crossover on C2s may have had several reasons - cost, space, heat transfer to the oil pan and chassis componet considerations, larger pipes, and larger mufflers that provided better sound attenuation without excessive back pressure.

System engineering decisions rarely have a single answer, so it becomes a matter of engineering judgment after weighing all the relevent technical and cost issues.

Duke

[William C.]

Re: purpose of C1 exhaust crossover pipes

I would not disagree with that at all...Different questions, different answers, and in many cases tremendously improved knowledge base and computer modeling capabilities than the late 50's early 60's that we started the discussion with (I think)