Centre exhaust X pipe modification
- Thread starter mjheathcote
- Start date
Fat Arnie
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I have spent much time deliberating X pipes as I wish to make the V8 in my P4 replica sound more like a V12.
In essence X and H pipes only work if you have exhaust pulses crossing the X from opposing sides every 90 degrees of engine rotation.
If you have ever wondered why a Ferrari V8 of 348/355/360/430/358 sounds the way it does, it is for this reason. BUT each of these cars has a flat plane crank.
The X pipe gives an aural benefit on an engine with 90 degree exhaust pluses as as the number of effective pulses in a single pipe is doubled. The flat plane crank is also much lighter as it has less counterweights and hence reciprocating mass.These engine respond well to an X-pipe as these tend to create a draw on the exhaust primaries, improving gas flow, hence power.
The sound is not really louder, but the pitch is much higher due to the extra pulses in a common outlet. Hence the exhaust pulse frequency is giving the impression of higher revs or more cylinders. (take your pick!)
On overrun X pipes have a tendency to introduce harmonics which do a good job of giving that whine only a V12 has.
None of the above will work on the 3200 and the 4200 as they have a conventional (like Ford and Chevy) cross plane crank.
The only car with a cross plane to come close is a GT40 iwth a "bag of snakes exhaust" The engine pitch changes dramatically in the GT40 compared to other cars using the 289ci Ford motor.
So where does this leave you with a Masser?
With the X pipe there will be no signifcant increase in noise if all other variables stay the same. What people are doing here is changing silencers at the same time. That is where the noise increase comes from.
On my P4 rep I am designing rear boxes (actually these will be the only silencers on the car
) so they have two inlets and outlets. One is straight through (not even perf tube) and allows the engine to run completely unsilenced so the car sounds like a proper 60's endurance car, the second pipe has a perf baffle which will cut the noise for MOT/road use.
The trick part is a valve in the exhaust (quite a few cars have these these days) controlled by a pneumatic or 12v actuator - I'm getting mine made, but they are commercially available.
Pic here
So you can then adjust the noise of your 3200/4200 depending upon situation.
In essence X and H pipes only work if you have exhaust pulses crossing the X from opposing sides every 90 degrees of engine rotation.
If you have ever wondered why a Ferrari V8 of 348/355/360/430/358 sounds the way it does, it is for this reason. BUT each of these cars has a flat plane crank.
The X pipe gives an aural benefit on an engine with 90 degree exhaust pluses as as the number of effective pulses in a single pipe is doubled. The flat plane crank is also much lighter as it has less counterweights and hence reciprocating mass.These engine respond well to an X-pipe as these tend to create a draw on the exhaust primaries, improving gas flow, hence power.
The sound is not really louder, but the pitch is much higher due to the extra pulses in a common outlet. Hence the exhaust pulse frequency is giving the impression of higher revs or more cylinders. (take your pick!)
On overrun X pipes have a tendency to introduce harmonics which do a good job of giving that whine only a V12 has.
None of the above will work on the 3200 and the 4200 as they have a conventional (like Ford and Chevy) cross plane crank.
The only car with a cross plane to come close is a GT40 iwth a "bag of snakes exhaust" The engine pitch changes dramatically in the GT40 compared to other cars using the 289ci Ford motor.
So where does this leave you with a Masser?
With the X pipe there will be no signifcant increase in noise if all other variables stay the same. What people are doing here is changing silencers at the same time. That is where the noise increase comes from.
On my P4 rep I am designing rear boxes (actually these will be the only silencers on the car
) so they have two inlets and outlets. One is straight through (not even perf tube) and allows the engine to run completely unsilenced so the car sounds like a proper 60's endurance car, the second pipe has a perf baffle which will cut the noise for MOT/road use. The trick part is a valve in the exhaust (quite a few cars have these these days) controlled by a pneumatic or 12v actuator - I'm getting mine made, but they are commercially available.
Pic here
So you can then adjust the noise of your 3200/4200 depending upon situation.
Emtee
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mjheathcote
Centenary Club
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Are Autoshield straight through rears only £200 then?
mjheathcote
Centenary Club
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Nah, £1500 new
http://www.performanceitalia.co.uk/... Spyder&part=MAS-4200-LARINIBB&cat_id=4#parts
I wish the sports cat replacement pipes where cheaper! £2,500...far too much!
hodroyd
Member
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- 14,150
OK so we are talking big bucks whichever way I look at it. She is going in for a grands worth of body tart up and detailing in a couple of weeks, so I will look at the exhaust situation after that. Unless of course we have a member who is itching to offload a Larini for biscuit money???