285 Vs 404

[yeti]

I currently have a 285 cam installed on an RPi 4.6. Twin Jenvey throttle bodies, ACT twin carbon plenum, lightened and balanced this-that-and-the-other, what looks on paper to be a good engine but has had problem after problem. However, that's not for here...

The car is currently in having the plenum resealed as it was leaking air all round through the cork gasket, new leads as one had split and I've been recommended to go for a 404 cam. This should liberate about 320bhp+ compared to the 280 it produces at the moment according to my new-best-friend.

My question is, what will a 404 do to driveability at low revs? How does the car idle? I'm not a cafe-racer or pub-cruiser but inevitably I'll be stuck in traffic/a town somewhere (Le Mans anyone?) and will have to spoend an hour in stop-start traffic. It's a Marcos Mantula by the way.

Cheers for any advice!

[rev-erend]

Unless your 285 (piper ?) has a problem then I would be very skeptical that changing to a 404 (mechanical or hydraulic) would ever increase the BHP by 40 bhp..

320 bhp is 69 bhp / litre which go be a very good figure if you got it. I would think you would need to be fully mapped (fuel and ignition) to get this.

Would the 404 give good driving manners - well I have a 404 Mechanical and mine drives well at slow speed but I have a 73mm single plenum .. which may be less induction area than you have.

What size inlets do you have - having a large inlet area can affect drivability but with careful mapping - I believe much of this can be dialed out.

[combemarshal]

>>>>>>>>>>>320 bhp is 69 bhp / litre which go be a very good figure if you got it. I would think you would need to be fully mapped (fuel and ignition) to get this.

It ain't that good! (the bhp/litre figure, Even my lowly very lightly modified Xantia is 101bhp/litre!)

[stevieturbo]

combemarshal said:

>>>>>>>>>>>320 bhp is 69 bhp / litre which go be a very good figure if you got it. I would think you would need to be fully mapped (fuel and ignition) to get this.

It ain't that good! (the bhp/litre figure, Even my lowly very lightly modified Xantia is 101bhp/litre!)

This is a rover V8 here.....

And how much torque does your Xantia have ? The Rover V8 is far from a modern design. Power outputs per litre generally are quite tame compared to modern stuff.

[rev-erend]

101 bhp / litre .. not something that a RV8 is capable of..

OK - the odd drag race engined car or with lots of tubro boost or blower..

But convention normally aspirated . that is not achievable.

Not that I know of.

[wildoliver]

Yes but your 101BHP is not from a N/A engine is it!

(makes mental note must buy xantia as they are clearly the most amazing car ever.)

[yeti]

Well I kept the 285, air leak/misfire fixed, new and improved leads were put in and a lot of mapping was done, predominantly on ignition timing settings.

Net result... a dyno print for 343bhp!! Not bad out of a 4.6 RV8, 74bhp/litre, it's up there with a few far more modern engines. The chap thought he could have squeezed 350bhp with the 404 but the bang-for-buck ratio was waaaay too low.

No, not quite up there with my old Integra Type-R either, but for a 50s V8 2 valve single cam pushrod engine I ain't complaining.

See you at Le Mans...

[rev-erend]

yeti said:

Well I kept the 285, air leak/misfire fixed, new and improved leads were put in and a lot of mapping was done, predominantly on ignition timing settings.

Net result... a dyno print for 343bhp!! Not bad out of a 4.6 RV8, 74bhp/litre, it's up there with a few far more modern engines. The chap thought he could have squeezed 350bhp with the 404 but the bang-for-buck ratio was waaaay too low.

No, not quite up there with my old Integra Type-R either, but for a 50s V8 2 valve single cam pushrod engine I ain't complaining.

See you at Le Mans...

That is really very good - the 404 has 300 degrees duration and a little more lift..

Hope your engine is nice and driveable.

I presume you have twin 54mm or 55mm throttle bodies..