264/256 vs 256/264

[MartinS]

I was looking for this topic for a long time but couldn't find any dyno proven data.

Has anyone input which IN/EX setup would perform better and why?

IMHO it's the 256/264 as the exhaust is more restrictive in our heads, but dyno numbers and some pro input would be cool.

Thanks guys!
Martin

[tolisspi]

thre are something here:
http://www.aeu86.org/viewtopic/tuned-4ag...light=dyno
http://www.aeu86.org/viewtopic/cams-for-...light=dyno

[MartinS]

No one could answer me the question. Not on C4ag, here nor hr.net. So I did my own little research over the internet.

Stock compared to 256-264 and 264-256:



Don't take this as 100% it's just based on numbers and a few calculations.
Stock engine peaks at 124hp here and the 256-264 / 264-256 combo at around 141 or 144hp. But I think its clear that the 264-256 setup looses more HP in lowend then gives advantage in top end.

--> 256-264 is the way to go!

[Uzelac]

And 272/272 ?

[MartinS]

I didn't try this one. But I would say between 6000-Redline you'll outperform the 256-264 setup maybe by 5hp. But from 0 - 6000 you'll lose massive overall. The 272 setup needs more than 8000RPM imho.

I did my calc's and I'll hit for 256-264 a decent ported head and 10:1 - 10.2:1 comp ratio on a fresh bottom end.

Edit:

Stock head, 9.4:1 cr

[tolisspi]

where did you find this software?
can you calc 272-272 10,3 lift and 13,2CR?

[Uzelac]

MartinS Wrote:I didn't try this one. But I would say between 6000-Redline you'll outperform the 256-264 setup maybe by 5hp. But from 0 - 6000 you'll lose massive overall. The 272 setup needs more than 8000RPM imho.

Sounds weird, that looks like great disadvantage for allmost nothing.
Around the net people are talking with 160 hp with 272 duration, even more with hicomp pistons and some more with tvis removed and standalone ECU.

Are you thinking all this or just changing cams when you say +5hp over 256/264 ?

[PatrickAE86]

maybe it sounds a bit nooby.. but can you run these numbers with a stock ecu? and those cams?..

isn't the engine running lean @ the higher rpm's then..?

what i would know:

are cams like these plug and play on a stock engine, and give you noticeable gain without adjusting the management.. (with no harsh becouse of crappy afr values..)

[MartinS]

No I made just:

Original 9.4 compression, stock head, stock header.
As I said it's just to compare one pair of cams to the other one.

[tolisspi]

software plz