Cams vs manifolds

[Hazz]

I promise you now, anthing with the OEM back box and a silencer in the B pipe will be quiet.

I ran a DC5 4-2, Spoon Decat and Spoon B pipe with a OEM back box and it sounded sweeeeeeeeeet.

OEM but with a serious rasp at about 5K, just didn't make the power though due to the DC5 4-2 (216bhp IIRC).

Ripped it off and put a TODA on there and bang, 240bhp 180ft/lb torque.

I've been out in one with a similar set up, toda mani, spoon silenced B-pipe, ITG intake and OEM backbox and I thought that sounded a fair bit louder than mine (AEM CAI & supersprint unsilenced)

 

[Suits]

No one appeared to have experiance of cams on stock manifolds, whilst I got some useful info I didn't actually get the answer I was looking for.

Again dude, it's not something people do, you'd not be able to get the best out of a set of cams without the gases being able to get out quick enough.

It's like buying pads before a skateboard, yeah it's cool and that and you can wear them about, but they won't do want they're designed to properly do until you get a skateboard.

 

[Suits]

I've been out in one with a similar set up, toda mani, spoon silenced B-pipe, ITG intake and OEM backbox and I thought that sounded a fair bit louder than mine (AEM CAI & supersprint unsilenced)

Well I'm shocked then.

Stay OEM man.

 

[Hazz]

I come from the world of minis where you don't get the best out of your manifolds and carbs without getting the right cam :lol:

There's more than one way to skin a cat.

 

[pulpmelon_R]

Hi Hazz

Without a race header I don't think aftermarket cams will make very much power at all. But good luck if you go that route, will look out for your dyno results.

 

[Hazz]

Will be a couple of months probably. I'll do chain and tensioner whilst I'm at it for peice of mind.

Going back to basic principles here, increased lift and duration will change the firing characteristics of the engine, shifting the natural powerband. The aftermarket manifolds act as an overall reduction of airflow friction to and from the valves (controlled by cams) so by my thinking (using visards power principles) the cams should make roughly 80% of the power they would with a free flowing exhaust manifold.

 

[Hazz]

Ps, that's visards a-series principles... Not necessarily applicable to the k20. But im willing to take the gamble.

 

[mikerj]

It's not just the physical restriction of the manifolds (which is very small anyway), the critical parameter is the tuned length of the primaries and secondaries. These lengths are designed to return negative pressure waves to the cylinders at the appropriate time to aid scavenging, and since this timing also depends on the cam timing it's obvious that the cam and exhaust must be matched to get the best results. Sticking a manifold designed for a full race spec. engine onto one running standard cams can easily lose you power and torque.

 

[devil84]

It's not just the physical restriction of the manifolds (which is very small anyway), the critical parameter is the tuned length of the primaries and secondaries. These lengths are designed to return negative pressure waves to the cylinders at the appropriate time to aid scavenging, and since this timing also depends on the cam timing it's obvious that the cam and exhaust must be matched to get the best results. Sticking a manifold designed for a full race spec. engine onto one running standard cams can easily lose you power and torque.

But we have seen that sticking on a 4-2-1 mani with a tune increases 10 to 15 bhp and increase in torque, with standard cams.

The standard defacto stage 1 mods are header, intake, intake mani and catback. Once you done this with a tune, then you go on to stage 2 mods such as cams and throttle body.? Bang for bucks get the stage one mods first, then move on to stage 2.

 

[Hazz]

Stage one and stage 2 are BULLSH1T, it's a pigeonhole which people put mods into. Nothing more.

A high duration cam will extract almost exactly the same amount of power with an OEM mani to any aftermarket cam. High lift cams will see less gains with a standard manifold but the fact remains that the valve is opening more and ldrawing more air in, making more power. As said, the OEM manifold isn't really that bad, not when you compare it to some other OEM manifolds from other models/manufacturers anyway. I honestly beleive that I will make decent figures if I pick the right cam, as said something with duration rather than lift would be best.

 

[pulpmelon_R]

Stage one and stage 2 are BULLSH1T, it's a pigeonhole which people put mods into. Nothing more.

A high duration cam will extract almost exactly the same amount of power with an OEM mani to any aftermarket cam. High lift cams will see less gains with a standard manifold but the fact remains that the valve is opening more and ldrawing more air in, making more power. As said, the OEM manifold isn't really that bad, not when you compare it to some other OEM manifolds from other models/manufacturers anyway. I honestly beleive that I will make decent figures if I pick the right cam, as said something with duration rather than lift would be best.

About 6 months ago everyone on here was telling me I was a dumb ass for wanting to fit a 3" exhaust to a NASP Honda. After I made 15hp extra in the midrange and 7hp at peak, the same armchair engine builders were pretty quiet...

I would say go for it, see if it works!

 

[dotty]

If you must stick with an oem header then get a DC5 one

 

[Hazz]

Not a bad idea Mr Dott.

 

[Suits]

Not a bad idea Mr Dott.

I had one on my EP3.

But binned it for a TODA.

These were it with a Gruppe 'M, 4-2 (DC5 header) 2-1 Spoon decat (you won't have) Spoon B pipe and OEM back box.

This is flywheel by the way.

 

[Hazz]

So, on the same dyno, only a header change from DC5 to Toda (and a re-map) got you from 217 to 240bhp?

 

[Suits]

So, on the same dyno, only a header change from DC5 to Toda (and a re-map) got you from 217 to 240bhp?

No, that read out there, is at SRR.

Romain then mapped the car again a few months later but used the one at his co-owned premises at Eurospec and got this....

If you look at the first run, you can see that's the original run (old map ) with the header and exhaust were chnaged for something more free flowing.