any performance in P6 exhaust manifolds ?

#1
Hello everybody.
I have these P6 exhaust manifolds . ( see pickture) I really like the look of them but i understand that they are a bad choice in a performance perspective.
But where are the limit? does any have some experience with them in a high performance matter? is possible to port them to better performance or are they just plain hopeless?
any dyno sheets out there :)
Best regards multi
 

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Penguin

Active Member
#2
with exhaust manifolds a lot depends on cam, with standard or fairly mild cams they are not that critical.

that manifold looks like an auto one to me, manual "s" ones are bigger bore and worth having
 

colnerov

Well-Known Member
#3
Hi, They are not ideal compared to tuned length or extractor manifolds but because of the space constraints in the bay they are a good compromise. As said try and get hold of the bigger (exit) bore ones.

Colin
 

cobraboy

Well-Known Member
#6
2" from the manifold, 2 x 90 deg bends, 1 1/2" connecting balance pipe between, 2 x 2"onward to two straight through cans which are 4" x 18 " then 45 deg out to side in front of rear wheels all in 2".
I did not fit the cam, it was in the motor when I purchased it. I was told it was a Kent 224 that had been re profiled and had had one dyno pull on a development engine.
 

Penguin

Active Member
#7
2" from the manifold, 2 x 90 deg bends, 1 1/2" connecting balance pipe between, 2 x 2"onward to two straight through cans which are 4" x 18 " then 45 deg out to side in front of rear wheels all in 2".
I did not fit the cam, it was in the motor when I purchased it. I was told it was a Kent 224 that had been re profiled and had had one dyno pull on a development engine.

cool thanks for the info
 

ghce

Well-Known Member
#8
There a good article called "Improving the P6" which goes thru performance gains of a flowed header, used to be on this site.
Also some rather good work backed up by rolling road tests done by a few regular contributors here on this forum.


Graeme
 

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#9
Thank you. that was the answer i was looking for. you see aim planning to make a 200-220hp engine so now i know that those 3500S manifold will not be the restriction on that :thumb:
Cobraboy: i really like the dyno graph. must be a lot of fun to drive. lots of torque from 1400rpm. but what is the rest of that engine? how many ccm.
intake manifold. carburetor. cylinder heads . compression ratio. and how is idle?
Again thank you all. this is very helpfull to me.
Cheers.
PS. is there any of those S manifolds lying around for sale and will any have the trouble sending them to Denmark.
 

cobraboy

Well-Known Member
#10
I would tidy up any 3500 s manifolds you get, the more you do to them the better they will be.
I think there are before and after overlays on that graph, the trouble is being colour blind I just have to read the numbers, if it says blah de blah hp or blah de blah torque, I just think either OK or o dear. I cannot actually see which line is which, although I could figure it out, but that would take up drinking time.
4.6 litre
Offenhauser 360 intake
Autolite 4100 1.12 carb
Ported and polished SD1 heads
Kent 224 cam
10.0 : 1 CR
Idle is good, not too lumpy

Anything can be posted to anywhere, you just need to fund it.
 
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