302 Hp Na Gti6 205

[Toddy 7]

More credibility for me personally would be if you addressed some of Sandy's questions/statements.

 

Facetious comment - So a difference of (302 -283) 19 bhp equates to a difference in terminal speed for the quarter mile of (119 - 111) 8mph? what are the other differences between the cars weight/Gearing/Traction control etc?

 

I personally struggle to see how transmission losses are applied consistently, surely the 205 platform is well known, therefore you should be able to apply an x% to wheel losses within a narrow band, i.e 14-16%.

For example a group of 306 gti6's go to the same rolling road on the same day and have transmission losses varying between 13 - 21%, that appears illogical to me.

 

On a side note I did enjoy reading your blog http://www.pug1off.c..._brackley/blog/

[welshpug 1,626]

varying losses are quite logical, condition of transmission bearings, gears cv joints, weight of wheels and tyres, construction of tyres and their condition.

camber and toe settings etc!

 

plus increased torque means more friction.

 

i dont remember the exact figures, but i saw gwynnespeeds saxo on a rr same day as nick charles's original 106 race engine.

 

the saxo's transmission lost about the same in bhp as the standard ma, but at 70bhp more, 211 to 150 bhp that day iirc.

[dav1 7]

This thread could get interesting.

[Sandy 189]

This is interesting. I stand by what I always say, that rolling roads produce estimated results and there are alot of holes in the data from that engine, as I said, even if you add the wheels figures to the losses shown, you don't get near the claimed flywheel figures. Most of the info and qualification to back that up is already written. I won't be having any rolling road shoot outs, too many variables at work to make absolute comparisons. If you want to dyno one of your top engines on the same dyno I use (fully geared up for TU and XU/EW), privately or publicly, then I'll gladly pay the fees to satisfy my own curiosity.

 

The engine shown of mine is same bore and stroke as yours Matt, Matt Saville told me what yours was, no titanium valvetrain or steel crank, not even slipper pistons. The cams are my own profiles and probably not as mild you'd imagine, gentle ramp/flank for durable and reliable performance. The high BMEP comes from very careful pipe tuning and refinement of the overall package. Several of my engines have dyno'd in the region of 230-240psi BMEP and several armchair experts have questioned those results, but I've had plenty chances to compare with other highly regarded builders on the same dyno and we calibrate regularly, especially if we see something unusual. I don't play games with results, I do anything I can to dial out potential errors and make the fairest possible comparisons, but the best verification is track performance; I've got a few championships to back that up.

[dav1 7]

Well good points by both ,Matt could answer some of sandys points about that run? Plus sandy could have a little rr shoot out with matts best engine an sandys best engine. Rr would be easyist as there engines are proberly in cars. ppl would love that. It's about Wat the people want aswell as they both show there skills. Come on lads would be good plus it's harmless.

[Batfink 201]

seems too much like d*ck waving. Both are producing championship winning engines which speaks volumes. Certainly more than a rolling road shootout will prove.

[Anthony 1,000]

seems too much like d*ck waving. Both are producing championship winning engines which speaks volumes. Certainly more than a rolling road shootout will prove.

This, absolutely.

 

Besides, how do you determine which engine would "win" on the rollers? The one with the highest peak figure? The one with the widest power band / torque spread? The one that's most tractable low down? Depending on what the engine in question has been designed with in mind, each of those could be the most important factor for a given application.

 

The graphs at the top of this page - assuming for a moment they're correct - should give a pretty good indication that there are two very different approaches being employed here.

[dav1 7]

Yes but this whole topic is questioning the 302bhp so that's what will be in question?

[pug1off 3]

I think people are getting confused between the green car and the blue. The blue car has the titanium valve gear and steel crank, hence the rpm, no doubt i'm imagining that aswell!

 

Look I'm at the rollers tomorrow so I'll get a copy of the plot with losses, wheel power and wheel speed all included which should answer everyones questions.

[wicked 103 3 Cars]

Interesting topic!

 

Isn't there a RR available with Dynapack equipment?

http://www.dynapack.com/

 

They don't have rollers to average the measured torque and would cancel out diff's in wheels, tires, camber etc...

[Sandy 189]

Hub dynos are really good for taking tyres out of the equation and we like them for incar setting up with the powerful and light cars that have grip problems. However they still have a few big variables in the transmission and just yesterday I was looking at some Dynapack hub dyno graphs we were sent for a Vauxhall 2 litre we'd just engine dyno'd, showing 312bhp and 207lbft, rather more than we saw! The 2 and 2.5 litre Vauxhalls we do are extremely consistent on the dyno, but show hugely varied results when they go out to rolling roads and hub dynos. I'd love to have faith in rolling road results, even it was one holy grail rolling road (as several claim to be); but the evidence is too strong against I'm afraid.

Edited May 3, 2012 by Sandy

[pug1off 3]

Apologies for the delay, we've had 4 cars on the rollers the last two days so its been a bit flat out.

 

Below are two graphs for you from Northampton Motorsport's very up-to-date Superflo Chassis Dyno, the first graph shows the flywheel power, wheel power, road speed and losses of the 205 in question. Take note of how losses increase in an exponential manner, especially noticable after 120mph. This is purely down to increased friction in the drivetrain, the gear oil, gears, cv joints, wheel bearings and most importantly - tyres. Imagine moving your hand slowly through a liquid, like a paddle, now move it as fast as you can and what happens?

 

Most cars would usually be done by 8000rpm so lets take that point as an example. As you can see the losses are around 40bhp, and the wheel speed - about 135mph. That sounds abit more like what you'd expect - right? I think the point here is that if you've never built an engine that can make 9700rpm and happens to reach 162mph when driven on the dyno in the most direct drive gear available, then you wouldn't necessarily know how losses behave at high speed.

 

So what would happen if the car was run in a lower gear to reduce wheel speed? - Simple, the wheel power would be higher due to increased torque and the losses would be reduced due to reduced friction, giving - you guessed it - THE SAME RESULT AT THE FLYWHEEL!

 

And thats why any rolling road you attend should, in my opinion measure losses, to be considered accurate. It's worth noting that this dyno produces almost identical figures to Emerald's Sun RAM 12 and Track "n" Road's TAT dynos.

 

[welshpug 1,626]

where's the torque reading ?

[pug1off 3]

Now here's another question...are the losses on this car particularly high? Could they suggest that the rpm was calculated incorrectly with wheel speed? Well here's an example of losses from an Mi16 that we mapped yesterday on the same size tyres vs the 205 in question. The graph show wheel power, losses and road speed.

 

As you can see the 302bhp car actually has lower losses, (very slightly) than the Mi16 race car but notice how these losses overtake that of the Mi16 at 7000rpm, why? Because the wheel speed of the 302bhp car at this point begins to exceed the critical 120mph.

 

The Mi16 at the end of its test is making roughly 130mph, now look at where the gti6 losses at the same wheel speed - THEY'RE LESS! This is probably due to the fact that the Racer is on slicks so has a slightly better patch on the rollers.

 

 

As I mentioned before I am very busy and find it difficult to post all the time but try to consider the facts presented here by a calibrated tool in a dyno cell worth over £100k vs a home-made Excel spreadsheet showing torque figures from a 2 litre n/a engine that are laughable to any expert engine builder, expecially at such low rpm.

 

My challenge remains in place and we'd also be more than happy to bring our cars along to a dyno day, (somewhere that measures losses) within a reasonable distance from our Brackley base and look forward to meeting some of you 205 enthusiasts.

 

[pug1off 3]

where's the torque reading ?

 

Torque?... no problem, If you put too much on a plot it gets a bit confusing!

 

I really have to leave it there or the wife will divorce me!

 

[Mad Scientist 106]

Difficult to understand without seeing the torque curves too, but from the graphs above it looks to the lamen like the mi16 would be the better car to drive anywhere except a drag strip. How would you describe the driveability of the 302bhp car? Was it designed for a specific purpose, or just as a demonstration?

 

There's no need for hostility from either side though IMO. Let's all stay friends on here!

[welshpug 1,626]

There's no need for hostility from either side though IMO. Let's all stay friends on here!

 

quite agree Pete, whichbegs the question why such a silly comment like the one below?

 

facts presented here by a calibrated tool in a dyno cell worth over £100k vs a home-made Excel spreadsheet showing torque figures from a 2 litre n/a engine that are laughable to any expert engine builder, expecially at such low rpm.

 

I wouldn't call Sandy's championship winning engines laughable

[wracing 19]

Can some one please explain how you measure losses?

[Mad Scientist 106]

Precisely why I said it! I may be wrong Matt, but I suspect the excel spreadsheet was populated by data from the calibrated and DIN corrected engine dyno used by Sandy.

[welshpug 1,626]

Can some one please explain how you measure losses?

 

 

 

 

though to answer it specifically...

 

Compare the engine dyno results with a RR wheel output

[Mad Scientist 106]

Bit of interesting reading here about coast down losses:

 

http://www.max-boost.co.uk/max-boost/internet_articles/Puma%20Race%20Engines%20Technical%20Guide%20-%20Measuring%20Engine%20power%20-%20engine%20dynos%20and%20rolling%20road%20dynos.htm

 

Can't pretend to agree with everything Puma racing write, but this fits with other books I've read.

 

 

[wracing 19]

Thanks welshpug for clearing that up for me

 

Can someone explain the conflicting information.

 

" losses are exponential and increase dramatically with high road speeds"

Yet

Peak wheel power is made according to the vid at 239.6hp@8200rpm

Yet

The 'flywheel' power graph shows 301.4@9600

 

And the comment its still climbing well it really isnt and had not been since 8200rpm

 

The graphs further up this page show the numbers don't tally, Why don't they?

 

Please explain?

 

James

Edited May 4, 2012 by wracing

[Mad Scientist 106]

Playing Devil's advocate, a quick dab of the brakes on coast down could easily exaggerate transmission losses. Imagine if that could make the "flywheel power" a touch over 300bhp. Would be quite a coup for YouTube wouldn't it?

 

There's no doubt that's a special engine though, with god only knows how much time and money in it. Titanium valve trains aren't cheap!

[stefan 4]

This is advertising at play here, and whose co'k is bigger. As said above, people want a showdown, but I’m afraid they can't get that. Advertising is a cold war game, no transparent and honest matchups here. It’s just a cloak and dagger fight for every customer and buck. The people want a ‘Pacquiao-Mayweather’(for boxing fans ) fight, which could very well never happen, both have too much to lose, and business is good as is.

[petert 554]

Could you please elaborate on how much of the valve train was titanium?

Edited May 5, 2012 by petert