Opinions on this dyno print out please

[Worzel]

Evening all,

I recently posted about options for building a new engine for my Caterham as a project. To throw a spanner in the works I've been offered a recently built engine which appeals as I can use it as a base to upgrade further and cost wise it works out much cheaper.

Spec of the engine is:

160 VVC as a starting point
VVC mechanism blanked off and Piper BP285H cams fitted
Jenvey throttle bodies
4-1 R300 exhaust
DTA S40 Pro ECU

I've been sent through a copy of the dyno plot, the shape of the torque curve and overall figures were less than I was expecting.






Could you take a look and offer any wisdom as to whether this seems like a decent set of figures and torque curve?

Thanks,

Jon

[DVandrews]

In my experience an engine of that spec. should make 185BHP+ and 140lb/ft+, the last half a dozen I have done to that spec? have certainly been around those figures. The torque is the telling factor.

Dave

[Worzel]

Thanks Dave. I've no reason to doubt the chap selling it regarding the spec of the parts fitted. Could the timing (it has. Verniers fitted) or mapping be less than optimal causing it to be down on torque?

When you say the torque is the telling factor, could you expand further?

Thanks,

Jon

[sjmmarsh]

It looks like the mapping has been done by the two Steves. They know Caterhams well and normally tune it to driveability rather than outright horsepower - a flat torque curve is normally preferable to a peaky one unless you need to extract the best race performance and redline it all the time.

Give track n road a call - they may be able to tell you what they tuned it for.

Steve

[DVandrews]

Either the map is right or it isn't, knowing the two Steves the map will be right. The 4-1 probably isn't helping the torque, it tends to kill the mid range and favour the very top, hence the peaky torque curve.

Dave

[Worzel]

Thanks guys, I'll give track 'n' road a call tomorrow.

If it's the 4-1 that's killing the bottom end should that not result in better figures further up?

Apologies if that's a bit of a simplistic view, currently trying getting up to speed on the topic!

Thanks,

Jon

[Worzel]

Evening, the chap has just got back to me with answers to some of the questions I asked him, he's just mentioned that he has retained the std VVC exh cam and has just replaced the inlet with a BP285H cam, hadn't read anything regarding this approach before. Does this help explain the shape of the curve? Is this approach an issue?

Thanks,

Jon

[DCL]

For what it is worth, I just built a Duratec that ended up with a similar shape (if not more exaggerated). It was all down to the exhaust, and, in my case, a 4-2-1 transformed the graph (blue) and is the only difference between the two graphs.



IMHO the cams are really designed as a pair and do need to be matched to the correct type of exhaust to obtain the optimum result. That's not to say one type of exhaust is better than the other, just that the subject is complex and it is usually easier to use tried and tested setups that others have had success with.

Edited by DCL on Thursday 3rd July 09:48

[V7SLR]

Worzel said:

I can use it as a base to upgrade further and cost wise it works out much cheaper

I assume the pistons are the VVC "160" items, if you want to go for much more power you'll need to investigate whether you should change to forged items and what it's going to cost you, dependent upon your plans.

[DVandrews]

The stock exhaust cam is hopeless, 252 degrees with 9.3mm lift. BP285H cams have 2 mm more lift and 14 degrees more duration, a massive difference. If he is using BP285H cams on the stock springs then it isn't safe, similarly the caps are at their limits as will the pistons be if they are not forged.

Dave

[curley]

If it's recently built why is the date on the dyno plot 2011 ?

[Worzel]

Blimey, that is a substantial difference just down to the exhaust, I didn't realise that it could have such a profound effect on the torque curve shape and absolute figures.

I'm due to speak to him again tomorrow so will ask him exactly what was fitted when he added the piper cam, he did say it was a kit but will specifically ask what was done. He did state that he checked that the pistons had 160 stamped on them so that's at least something.

Hadn't noticed the date on the print out, good spot!

My current thinking that this isn't an ideal route based on some of the points raised here. Sounded like a good opportunity to start with but not so much now

Thanks,

Jon