Camshafts and Superchargers

Post by **Coops** » Sun Jul 26, 2015 4:33 pm

I know im meant to be leaving things alone for a bit but its still playing around in my head lol,

Cam recommendations with a charger????
currently running a Crower cam.

stevieturbo · Post by **stevieturbo** » Tue Jul 28, 2015 5:42 pm

Coops wrote:I know im meant to be leaving things alone for a bit but its still playing around in my head lol,

Cam recommendations with a charger????
currently running a Crower cam.

Unless you're looking to change either idle manners or upper rpm range...save your money.

I think you mentioned cam details before, and it really didnt look too bad at all.

cammmy · Post by **cammmy** » Wed Jul 29, 2015 12:21 pm

Also, what style of charger? Makes a difference as to what you would choose.

Post by **Coops** » Fri Jul 31, 2015 5:44 am

Sorry for late reply been busy at work.

Rotrex C38-91 centrifugal supercharger

And current cam specs http://www.v8forum.co.uk/50233.htm

Post by **Coops** » Thu Aug 06, 2015 4:11 pm

is the piper BP300 a better cam to use?
as im needing a new cam and lifters now I may aswell use a more suited cam if there is one over the current crower cam,

stevieturbo · Post by **stevieturbo** » Thu Aug 06, 2015 5:04 pm

IMO 300 just sounds like too much.

Unless you know someone who has a similar size engine and can give you an idea of how it feels, I'd tread carefully.

I'm not even using that much duration and my engine is around 6.3

The easiest mistake to make is to go too big, and all it will do is kill the lower rpm's and move the powerband up, but not actually add any power.
So it just makes it less user friendly for almost no gain.

I'm not saying it will definitely happen, but it's happened on other engines I've worked on.

But the blower will be more forgiving in that respect and to a degree maybe band aid a poor cam choice.

It is a difficult decision, but around 285 duration really isnt a bad number, and keep the valve timings with either low, or no overlap.

But there are few negatives to playing a little safe and picking the cam below what you think you might want.

Post by **Coops** » Thu Aug 06, 2015 5:40 pm

hI Stevie,
im no cam expert that's why I thought I would throw it out there for advice,
as want to make sure the new engine build is right and don't get no I told you so comments lol

unstable load · Post by **unstable load** » Fri Aug 07, 2015 5:28 am

Coops wrote:want to make sure the new engine build is right and don't get no I told you so comments lol

You'll probably still get those, regardless. Hindsight always makes some people experts, particularly if it's someone else's misfortune.

stevieturbo · Post by **stevieturbo** » Fri Aug 07, 2015 5:52 am

Play it safe and let the blower do most of the work.

If you were happy with the previous cam in terms of idle, driving, power band etc, leave it as is.

If you need a little more power then let the blower make up the difference.

However if you are seeking more rpm's etc, then stepping up with the cam may be required.

SuperV8 · Post by **SuperV8** » Fri Aug 07, 2015 11:31 am

I'm using Piper 270 for my 4.6 centrifugally supercharged engine. Standard heads and bottom end.
Works great for me, pulls like a train, really starts going above 2500.
Maybe a 285 or 300 would be better? maybe they would be worse? who knows unless you can test each in your engine!
The majority of my driving is on the road and i'm never realistically going to spend much time above 5000rpm so I don't think a longer duration cam would help me.
Personally if I had flowed heads and 6500 rev limit I would probably think about an 285.

Tom.

Blown v8 · Post by **Blown v8** » Fri Aug 07, 2015 3:26 pm

Mines on 114* lobe centres,over 520" lift,with more duration on the exhaust side ! Mines a Rootes style blower,
Centrifugal blowers tend to like a cam with more overlap,
To throw something else into the mix,Steve Wells's rover engined pop pick-up that has run 8.3, has 110* lobe centres,(Rootes blower)
But he runs on methanol,
The trouble is,the Internet has opened up so much more information,when I chose my cam,I just had good old books to help guide me,
good luck

stevieturbo · Post by **stevieturbo** » Fri Aug 07, 2015 6:07 pm

The other problem is comparing full race/drag cars, to what is still a road car.

Also factor in emissions for MOT, go too big and that can become more awkward.

IMO even though Rover heads dont flow that well, I see no reason to encourage lots of overlap...keep it down to very small amounts, if any at all.

bigaldart · Post by **bigaldart** » Sat Aug 08, 2015 3:39 pm

You can't really go wrong with the Real Steel blower cam, not too much lift, very little overlap. We have run just about everything available at one time or another and this cam just flat out works. Valve train is happy and stable, we have seen well over 8000 rpm when the driver messed with the limiter settings

Let the blower do the work, but watch the compression, with little overlap the dynamic compression will be higher than a more racey type cam. Running petrol I would not want more than 9 : 1 and personally would look for 8.5 : 1 as a maximum.

Alan

Blown v8 · Post by **Blown v8** » Sat Aug 08, 2015 4:00 pm

Just looked at the specs of the real steel blower cam,specs are not bad,
But I personally prefer a mechanical cam !
Just my 2p

bigaldart · Post by **bigaldart** » Sat Aug 08, 2015 5:55 pm

Just take the specs and have a solid lifter grind done, we did have one to solid lifter spec, again it was a great grind and made good power, we even ran it at one time with hydraulics on the exhaust and solid on the intake. I cannot say we have ever made more power with a bigger cam, timeslips are the only clue I have and the blower cam has always made the best numbers. Things evolve so quickly on a race engine so other changes can have an effect. Personally I live and die by the time slip.

Alan

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