[race_prep] Our Hillclimb/sprint 205

[Anthony 1,003]

That's none too shabby, and the power/torque curve looks very good for such peak figures! That from 1997cc, correct?

 

I know you've mentioned them in threads previously, but how does that compare to the TU and EW engines you've done? I know you were getting better results with them, but you mentioned that you put what you learnt from those engines into this XU and - I'm assuming - improved as a result? I vaguely recall you were somewhere around 98lbft/litre from the EW?

 

Do you have any plans to run this engine past 8k given that from the graph it looks like there's still more to come, or have you limited it there for longeivity?

[alexcrosse 124]

Do you calibrate at 500rpm intervals and then interpolate the rest or something?

[Sandy 191]

We steady state test and map every 500rpm for most of the rpm range, but low down smaller intervals are used where spiky changes occur. A well rounded engine like this doesn't need smaller intervals in the main operating range, the dynamic mapping in the car after takes care of other variations. Dyno testing needs to be scientific and steady state is alot more scientific than dynamic testing for comparing values.

 

I'm very pleased with the curve and the progressive throttle behaviour, more important to me than Pub peak figures! The best lbft/litre i've seen to date is the last XU10 I did, comparable with the EW. This engine used a new cam profile, which is a bit of a departure from my usual method; not entirely sure it's a net gain TBH and it's harsher on the valvetrain, but runs cleaner and smoother low down at part throttle. Likewise the exhaust manifold I originally designed for a 2.3, so it's probably not perfect for this engine. My best bhp/litre to date remains a TU, but looking at the way this one was climbing, it may have gone on to challenge that! I still think ultimately the EW will be better, for various reasons in the design, but this had to be XU for regs. I will probably limit it around 8500rpm, see how it feels in the car. But running up there in bursts is a lot less stressful than holding it there for nearly 20 seconds on the dyno!

 

1997cc yes, 85mm bore x 88mm stroke.

Edited August 24, 2012 by Sandy

[alexcrosse 124]

ok - just asking after seeing the power curve plot. It will be good to see the transient curve when you have it done. If power is still climbing at 8500rpm would you consider calmer cams to gain a bit more in your range?

 

try having to hold a v8 single turbo diesel at 1100nm for 10 minutes on an engine dyno - aneurysm spec.

[Sandy 191]

I can imagine! This dyno doesn't like big engines at low revs!

 

My previous cam spec did exactly that, fuller curve 4-8k, but the head and pipe tuning play with that alot too. I'll see what this feels like in the car before I judge it. John made a subtle spec change on his 2.5s last year that made no difference to the dyno figures to speak of, but made them feel alot "fuller" in the car.

[Dj_mini 7]

Looks great sandy must be a bit of pressure building a motor for colin

When is the first event?

[maxirallye 2]

Nice one Sandy, is Colin competing this weekend as planned?

 

Thanks

[Sandy 191]

Yeah, it's alot like that Dan! But big payback for all the help he's given me over the last few years.

 

We were heading for Pentillie today, but that's obviously out, hopefully get it in the rollers to refine the map this week and test perhaps. All going well with that, perhaps Wiscombe next weekend.

Edited August 25, 2012 by Sandy

[alexcrosse 124]

who's rolls do you use out of interest?

[welshpug 1,661]

Alvin Powells in saltash

 

Was funny me and dan trekking down to cornwall to be met by a welshman!

[dcc 855]

Matey boy. Great tea brewererer

[Sandy 191]

It might be Alvin's, might be Mark's, depends which is the most convenient on the day, but neither will be able to properly hold this one at the top end, it won't be for figures, just to enable me to refine the dynamic map behaviour against a load in the car.

 

Colin's put alot more time to it, getting the engine in and despite all the dry builds done before, there was still some fettling needed to get the subframe in place around it. I got the loom done yesterday (even at Saturday pace!) and it's not looking too far away now.

 

Colin and Paul getting the engine/exhaust in:

 

 

Dean (Cyb3r) tries the seat for size with TIGger Dave looking on. We blamed Dave for all the fitting issues ("road wheels" fitted for trailer/rollers, not the proper ones):

[calvinhorse 870]

Christ that engine is low! What's the driveshaft angle like?

[Sandy 191]

Not bad, better than the old car. Part of the re-location plan was to rotate the engine/box to bring the diff up.

[Cameron 16]

Does that shift the CG of the engine forwards much, or were you also able to move the engine back a bit?

[Sandy 191]

It is back a bit and engine/box CG is probably very marginally further forward, but alot lower too, any imagined detriment to the turn in is more than likely compensated by reduced roll moment at the front and traction off the line. Let alone the benefits it brought to other areas of the package, that are far reaching.

[Cameron 16]

Yeah I imagine the trade-off would be very much in favour of the lower CG.

[calvinhorse 870]

So the engine is tilted forwards more to raise the diff?

Sorry if this has already been covered! I'm pretty sure I've read it all tho

[Sandy 191]

The whole unit is "rotated" and lowered, engine almost upright, the engine mounts are entirely fabricated.

[kyepan 291]

Looking good sandy, would be great to see some in car when it goes up the hill.

[Sandy 191]

Colin's just bought a Gopro kit, so that's very much on.

[kyepan 291]

did you guys end up doing a flat bottom and diffuser?

[welshpug 1,661]

did you guys end up doing a flat bottom and diffuser?

 

 

Diffuser and floor panels:

 

[kyepan 291]

ah good, would be good to see an underbody shot of the rear including exhaust routing!

[dcc 855]

what and let the man give away all his secrets?

 

some things should be left to the fairies to allow our imagination!