Standard V Modified 8v And 16v Graphs

[smckeown 1]

Well one of us bored in Frankfurt....

 

I have been meaning to do this for a while, but we have the opportunity to compare these combinations on the same rollers.

 

Here are the comparisons:

1 - Factory figures for the XU9JA

2 - Factory figures for the XU9J4

3 - Modified XU9JA (mine) - mods are freshly rebuilt, BVH, 45mm TBS, ECU, 11:25, 287deg cam, GrpA exh.)

4 - Modified XU9J4 (Mattsav's & same rollers as 3) - mods are freshly rebuilt, 48mm TBs, ECU, 283deg cam, GrpN exh.)

 

 

 

Edited December 6, 2006 by smckeown

[B1ack_Mi16 67]

How come mattsav got more power than your's in the lower revs while the torque graphs indicate you got more torque?

 

Are some of the graphs switched by accident?

[smckeown 1]

yeah someone on psooc pointed out that the power and torque figures don't match..i'm just sorting it out...

 

** ok now I have generated the power figures from the torque figures, hopefully that makes them consistent

Edited December 6, 2006 by smckeown

[28CRAIG 2]

Its is good to see the comparison in torque between your engine and a modified mi there is so much more torque from your engine but then the mi makes more power high up.

 

And it shows that a std mi has as much torque as a std 8v at low revs but much more at high rpm the 8v is flat from 2k

[dee205 3]

It looks as though the standard Mi makes more power and torque than one with tb's and management.. until past 5500rpm..

This can't be right surely?

Why go to all the time, efford and thousands if you have to rev the nuts off it or face a less responsive than standard car?

 

 

Is there something wrong here?

 

 

Damien

[smckeown 1]

It looks as though the standard Mi makes more power and torque than one with tb's and management.. until past 5500rpm..

This can't be right surely?

Why go to all the time, efford and thousands if you have to rev the nuts off it or face a less responsive than standard car?

Is there something wrong here?

Damien

 

The 48mm TBs are killing low and mid range torque, because the gas speed is too high, matt knows this. So it's not truly representtaive of a tuned mi, but the only one I have on the same rollers as me

[Sandy 191]

Gas speed to low*

[smckeown 1]

ah yes, why on earth did i type high...doughnut!

[Sandy 191]

Nice work sean, but a shame you've left the XU9J2 off, because that's the interesting one!

[B1ack_Mi16 67]

Nice work sean, but a shame you've left the XU9J2 off, because that's the interesting one!

 

When I was 18 my dad had a 1988 405 GRi with the XU9J2 engine.

 

It was a pretty amazing engine, it felt so fast and responsive compared to my DFW 405 Mi16 I was almost jealous. The GRi was faster than the Mi16 from standstill and to somewhere up to 60-70km/h I believe.

 

Instant throttleresponse and very good torque at least up to about 4500-5000rpm if I remember correctly.

 

Think this must be a "better" engine than the XU9JA in may ways.

[smckeown 1]

Nice work sean, but a shame you've left the XU9J2 off, because that's the interesting one!

 

 

I'd happily add it in a jiffy if I could find the official torque graph

[Sandy 191]

The figures are on that XU PDF

[smckeown 1]

ah this PDF

 

Right I have updated the graphs to include it. Man how much low down torque has that got, wow that thing pulls like a train! Pity it runs out of puff so early.

 

So there you have the 2 extremes, the XU9J4 and the XU9J2. Any the best compsomise ? That will the the XU9JA BVH on TBS

 

Sean

[Sandy 191]

The main reason it runs out of puff is probably the tiny TB and small bore tracts. I know a 1.8 205 with this head giving 155bhp at the wheels on the same rollers that Huxley's 2 litre Mi16 gave 170 at the wheels.

[Robsbc 0 1 Cars]

Huxley's 2 litre Mi16 gave 170 at the wheels? Is he happy about that? With 20% transmission loss his mi16 is producing around 204BHP...He was hoping for 220ish.

Edited December 7, 2006 by Robsbc

[KRISKARRERA 2 1 Cars]

These are official - from that pdf:

(Courtesy of Grim.badger)

 

Looks like the XU9J2 is best as a daily driver!

Edited December 8, 2006 by KRISKARRERA

[Sandy 191]

Huxley's 2 litre Mi16 gave 170 at the wheels? Is he happy about that? With 20% transmission loss his mi16 is producing around 204BHP...He was hoping for 220ish.

Those rollers read slightly lower than most, for example, Colin Satchell's 1.93 Mi16 gave 183bhp at the wheels there, but 200bhp at the wheels at Emerald previously. On some rollers I expect Huxley would see nearer that!

 

Looks like the XU9J2 is best as a daily driver!

It's a much better head than most people think

Edited December 8, 2006 by sandy309

[Grim.Badger 15]

I should point out that those graphs are bodged a bit see

 

In defence of the XU9JA that super flat torque curve has got to count for something, plus it's a much closer match to the MI16 than I thought until about 5000/5500 rpm. As a daily drive I'd say the XU9JA has the crown as the graphs suggest a much smoother drive.

 

Sean, would you still say yours is technically an XU9JA as surely by changing the valve size and camshaft its not an XU9JA in the same way the valve sizes and camshaft distinguish the XU9J2 from the XU9JA (I think)? Maybe an XU9McKeown as it was built specifically for you?

[Sandy 191]

In defence of the XU9JA that super flat torque curve has got to count for something, plus it's a much closer match to the MI16 than I thought until about 5000/5500 rpm. As a daily drive I'd say the XU9JA has the crown as the graphs suggest a much smoother drive.

So let me get this right, you'd prefer less torque over most of the rpm range for a flatter curve? Strange boy.

 

The XU9J2 has the same valve sizes as the XU9JA and the cam has less lift on overlap, but the basic inlet port design is much better, using making good use more of the valve curtain area.

[smckeown 1]

I have updated the graphs slightly, just to get more graph and less blank space in the area, it's worked particularly well on the torque graph.

 

I have dave's standard BV head, i think it's more of a rally oriented design rather than race, but that's what I prefer to be honest.

 

I'd be interested to see a graph for a similar spec car on a longman's head. As I believe the port for more top end; just wondering if they still get a reasonable mid range at the same time ?

Edited December 8, 2006 by smckeown

[Grim.Badger 15]

So let me get this right, you'd prefer less torque over most of the rpm range for a flatter curve? Strange boy.

 

The XU9J2 has the same valve sizes as the XU9JA and the cam has less lift on overlap, but the basic inlet port design is much better, using making good use more of the valve curtain area.

 

As a daily drive (pottering about town and motorways) I think it would be better, but I've not driven either of the Mi's so I can't really comment on the fun factor. I think I've driven the XU9J2 that was in a Xantia and found it annoying as the power wasn't consistent through the range and had flat spots. Thinking about it the engine probably wasn't in the best condition if it was doing this as it felt nothing like my XU9JA. Also having to pull a Xantia won't have helped

I would like an MI, at least for a while, but I think I'd start collecting points if I got one

 

So it's just really the inlet and cam that's different on the XU9J2?

[Anthony 1,003]

I think I've driven the XU9J2 that was in a Xantia and found it annoying as the power wasn't consistent through the range and had flat spots. Thinking about it the engine probably wasn't in the best condition if it was doing this as it felt nothing like my XU9JA

Wouldn't have been an XU9J2 in an Xantia - would have either been an XU7JP or XU10J2 (1.8 and 2.0 8v respectively). XU9J2's were only in BX's and Phase 1 405's that I'm aware of.

 

So let me get this right, you'd prefer less torque over most of the rpm range for a flatter curve? Strange boy.

Main issue I have with the XU9J2 engine is that whilst it's torquey and good for pulling a 405 up the motorway, its complete lack of top end renders the engine as dull as dishwater to drive - it always feels like its throwing in the towel about 500rpm too early and becomes frustrating. Maybe in a fettled format with a hotter cam and a better inlet then it'd be good, but in standard form it reminds me of a diesel.

 

So yes, oddly I'm saying that in this instance I'd prefer less torque low down in exchange for shifting the powerband up a few hundred rpm. Usually I'd be looking towards doing the opposite, but in my opinion the XU9J2 is just too strangled at top end - to the point of being frustrating frankly.

[Sandy 191]

Perceived value eh!

[jackherer 543]

Main issue I have with the XU9J2 engine is that whilst it's torquey and good for pulling a 405 up the motorway, its complete lack of top end renders the engine as dull as dishwater to drive - it always feels like its throwing in the towel about 500rpm too early and becomes frustrating.

 

I've never driven a 405 but I've had several 8v GTI BXs with the XU9J2 engine and I think they are brilliant, if I wasn't addicted to Mi16s I would definitely try one in a 205. The BXs run the same gear ratios as a 205 1.9 and IIRC 405 SRIs have considerably longer gearing which may have influenced your opinion if you've only driven a 405 with one of these engines?

[smckeown 1]

I've tracked down the official figures for the gti6 and added them to the graphs on the first page. Impressive mid range torque