Rr Results Xu7j4rs

[28CRAIG 2]

Engine spec

Standard XU7 bottom end, XU10J4RS head standard except 3angle valve's with 1.2mm of lift at TDC on the inlet cam and 1.0mm lift on exhaust cam. It's got the standard RS manifold and inlet, engine management is dta e48.

 

[pip470 61]

So glad someone has results for this, can you post up the peaks and rpms please as id be just guesing from the pics. Torque looks fairly consistant accross the rev range which is really nice. Looks impressive though, well done. A really good hike it looks like.

[Batfink 201]

125ish at the wheels. Not to be sniffed at

How is the low down performance. Is the gti-6 head not too big a ports for the lower capacity engine?

[James_R 3]

Looks like a nice graph, and 160BHP from 4-7krpm looks like a touch of retard on the cam timing is needed but bet that drives awesome!!

[welshpug 1,661]

Nice result, only 4 bhp less than the 200cc bigger iron block, though the torque is a fair amount lower, there is a decent spread

[JeffR 51]

I had an RS inlet cam measured a while back-0.047" @ TDC, so that (inlet) cam timing looks about standard(?)

 

Good result 'tho compared to my standard GTi6 which made 123hp (92Kw) at the wheels.

[Baz 421]

 

Nice power and torque, without the heavy block!

 

What does it drive like, similar delivery/characteristics as a std '6 Craig?

Edited September 22, 2009 by Baz

[Batfink 201]

I had an RS inlet cam measured a while back-0.047" @ TDC, so that (inlet) cam timing looks about standard(?)

 

Good result 'tho compared to my standard GTi6 which made 123hp (92Kw) at the wheels.

 

is your gti-6 sick? you should have around 140 at the wheels for that engine!

 

Kev

[welshpug 1,661]

if you look at the graph above you'll see a similar loss between the fly and wheel figures to JeffR's presumably standard engine, this is common with this type of RR setup, I've spoken to a few operators and they say its because of the double roller setup, the figures look far more realistic if you halve the loss figure.

 

i.e Jeff's @ wheels figure is much the same as Craig's, which would be around the 140 mark if you halve the losses.

[Galifrey 1]

if you look at the graph above you'll see a similar loss between the fly and wheel figures to JeffR's presumably standard engine, this is common with this type of RR setup, I've spoken to a few operators and they say its because of the double roller setup, the figures look far more realistic if you halve the loss figure.

 

i.e Jeff's @ wheels figure is much the same as Craig's, which would be around the 140 mark if you halve the losses.

 

I agree, this type of dyno gives BS figures at the wheel, typically 30% TL as opposed to the more realistic 15% for transmission loss.

 

However, the software seems to be able to adjust for it, and get a similar "flywheel" result to others.

 

It has always appeared to me, that looking at these graphs, there is a lot of inherrent loss in the rollers which shows up on the rolldown test as transmission loss.

 

Its annoying when you want to see a more accurate WHP figure, but as Welshpug says, halve the loss and add it to the wheel figure and it is pretty much spot on compared to other dynos.

[28CRAIG 2]

125ish at the wheels. Not to be sniffed at

How is the low down performance. Is the gti-6 head not too big a ports for the lower capacity engine?

 

Low down performance seems o.k not really had a chance to drive it i had a issue with a rear wheel falling off on the way home. Every says the ports are too big but i guess they are o.k just not ideal definitly better than the standard xu7 ports

 

Looks like a nice graph, and 160BHP from 4-7krpm looks like a touch of retard on the cam timing is needed but bet that drives awesome!!

 

He did say he put a extra bit of advance on and the the power was alot better the original map was from Sandy's old xu7 on bodies.

 

Nice power and torque, without the heavy block!

 

What does it drive like, similar delivery/characteristics as a std '6 Craig?

 

More like a Mi16 than a gti6 just seems very responsive even with the 1.9 box you will have to take it out when i sort a few of the issues out there is a bit more torque and power to come from it.

 

Not sure if it's worth looking at cams and sticking the 42mm bodies on aswell.

[Baz 421]

Not sure if it's worth looking at cams and sticking the 42mm bodies on aswell.

 

Of course it is!!

[Alastairh 47]

Nice result. Its good to see you finally got away from that 8v

 

Just replying to your pm...

 

Al

[28CRAIG 2]

Of course it is!!

 

I think i will fit my ATB first and get some new rear shocks. We will see about the bodies and cams, it would be cool to run 8 injectors and i think i could get around 108bhp per litre with the right inlet lengths

[tom_m 0]

nice!

[pablo 0]

howcome the torque and bhp dont cross at 5250? The scales are the same for torque and bhp

 

(curiosity not having a dig)

[welshpug 1,661]

because it was measured in Nm not LBFT.

[pablo 0]

thatll be it then cheers

[Galifrey 1]

because it was measured in Nm not LBFT.

 

A pet hate of mine...

 

Mixing metric and imperial on same graph (so to speak)

 

BHP and lb/ft

 

KW and KG/M

 

Nm is so random!

 

[jackherer 543]

Nm is so random!

 

If anything is correct its Nm, thats the SI unit after all.

[Galifrey 1]

If anything is correct its Nm, thats the SI unit after all.

 

I dont mean random in terms of its figure, I mean random in terms of amongst its peer group.

 

We talk BHP and lbs/ft you dont mix BHP and NM as its almost impossible to compare the 2 figures on a graph in terms of their interaction. Couple that with the dynos grossly innacurate transmission loss figure and whp, and the whole dyno run becomes even more meaningless than a typical dyno run

 

Powerstation use this type of dyno, and for a dyno that estimates fwHP I would at least expect an accurate wT and wBHP not another derived figure and mixed metric/imperial printouts.

 

I guess I expect too much

 

[Revant01 0]

Engine spec

Standard XU7 bottom end, XU10J4RS head standard except 3angle valve's with 1.2mm of lift at TDC on the inlet cam and 1.0mm lift on exhaust cam. It's got the standard RS manifold and inlet, engine management is dta e48.

 

Thats a very positive outcome, better than I was expecting for this setup. How do you think this would compare to the same setup with a ported xu7 head. Would the smaller inlets give a bit more torque down low (and less on top) or do you think it would supress it right across the board?

 

Alex.

Edited September 23, 2009 by Revant01

[petert 588]

We talk BHP and lbs/ft you dont mix BHP and NM as its almost impossible to compare the 2 figures on a graph in terms of their interaction.

 

Why? It's just units. The shape of the torque curve will be the same whether a factor of 1.34 has been applied or not. Even think of the vertical axis. Imagine how the shape of the curve would alter if the range was 0-250Nm or 50-200Nm or even 0-500Nm? The dyno operator can make it what he wants, then we think wow, how flat is flat? Or gee, isn't that a disappointingly pointy torque curve? must be a bugger to drive.

[Galifrey 1]

Why? It's just units. The shape of the torque curve will be the same whether a factor of 1.34 has been applied or not. Even think of the vertical axis. Imagine how the shape of the curve would alter if the range was 0-250Nm or 50-200Nm or even 0-500Nm? The dyno operator can make it what he wants, then we think wow, how flat is flat? Or gee, isn't that a disappointingly pointy torque curve? must be a bugger to drive.

 

Units is exactly the point.. sure you can see it, but its a lot easier to spot an "operator adjusment" and a BS dyno when they use the same units, thats why I dont like it.

 

Anyway, not going to hijack this thread anymore, read my signature if you dont agree with me

 

 

(Signature applies to me and everyone)

[28CRAIG 2]

Thats a very positive outcome, better than I was expecting for this setup. How do you think this would compare to the same setup with a ported xu7 head. Would the smaller inlets give a bit more torque down low (and less on top) or do you think it would supress it right across the board?

 

Alex.

 

I guess if the xu7 head was ported to suit the spec of the engine it would be better but it all comes down to budget, my engine with the rebuilt head, belts and gaskets cost less than to get the xu7 head ported

 

Have you seen Dixon's build topic that will give you an idea of what can be achieved with a bigger budget.