JMC's 1.9l G60

Thats impressive how he found extra grunt throughout the whole range.Just goes to show ho w a bad map can undo all someones hard work/cash/time/will to live.



What injectors are you currently running?

Yes, it does show how a bad map can really screw things up. To be fair, there are 2 other things going on i) the previous runs were done in summer with much higher ambient temperature and ii) they were done on a different rolling road, so absolute comparison may be slightly off.
But even so, it's a big improvement.

Hmm, just checked on the injectors. I thought I was getting red tops, but on the invoice, they are down as 315's. What's the flow of red tops supposed to be?

315 @ 3bar.They will be maxing out for your app.

Glad you've got it sorted. Much better numbers! You'll be able to compare your figures to others that have used stealth's rollers, which is helpful. My 315's @ 3 bar are also maxed. Time for some 420cc lucas items for later in the year when the new head is paid for.

Good to see progress being made on another project over the winter.

Finally a good map Jonathan Getting some good power now. How does it feel on the butt dyno?

It feels good Stu. Finally I feel as though it's been set up properly. I have actually got half an hour with Surrey Rolling Road tomorrow, so I can get a direct comparison with my old readings. Be interesting to see how theirs compares to Stealths.

Just remembered something guys - Vince suggested changing the fuel pressure reg in stead of changing the injectors, going to a 4 bar one. Does the flow of the injectors increase proportionally to the pressure?

jmc wrote:Just remembered something guys - Vince suggested changing the fuel pressure reg in stead of changing the injectors, going to a 4 bar one. Does the flow of the injectors increase proportionally to the pressure?

just think of it as increasing fuel flow rate.
Thats why I said your reds flow 315cc of fuel at 3bar.
@ a higher or lower rail pressure they will flow more or less.
However it is not directly proportional with relatively large increases in rail pressure giving relatively smaller increases in fuel flow rate.

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I think you want to be thinking about 440 cc injectors and possibly uprating the rest of your fuel delivery system.
Anyway..
enjoy.

Found the fuel pump info for a mate

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Cool, thanks Simon

Hmm, just had an interesting session at Surrey Rolling Road. Given that's where all my work has been done in the past I wanted to see how their numbers compared to Stealths now my system has been tuned. We set up the runs as closely as possible (bonnet up), and got the following numbers.

Surrey Rolling Road
195.7 bhp wheels (233.3 bhp flywheel) at 6300rpm
172 lbft wheels (203 lbft flywheel) at 5500rpm

Stealth numbers
203 bhp wheels (246 bhp flywheel) at 6121rpm
196 lbft wheels (222 lbft flywheel) at 5350rpm

Now I've not refuelled, tyres pressures were the same, and the temperature was similar, so it's food for thought...

Scarily thats the same values for the new Schrick cam (run on a nice cold day today) that I got for the Piper cam in the middle of summer, so I feel somewhat gutted now . Still c'est la vie, and there are is no doubt it is a fun car

It does explain why when I've compared my setups with others, I've always felt a bit down on numbers.

Although the numbers are the same the drive is very different, shows how its alot more than just a number thats important, Also your car may have different tyre pressures on the same rolling road plus loads of other stuff, good to have a comparison from the same place though and as you say so long as its fun then thats the main thing.

So have you thought of getting the Piper back in and a stealth map again, all just for comparison of course.

This is why I use Awesome-GTi for comparison of my engine changes. It's expensive at £65 a pop but you can get an idea of how your engine power compares to other cars that have been on the rollers through the website's rolling road day section. My flywheel bhp at chipwizards was something like 230bhp but at awesome it was a more believable 216bhp.

The Piper has gone Simon - I sold it as I was assured that 'the Schrick is a much better cam'. Hopefully next time I wont be so gullible.

One thing Charlie mentioned today as well - 'your injectors are maxing out'. I really really am going to have to do something about that next.

And yes, it's very easy to fall into a comparison trap CTW - thats why I wanted to try it at SRR. Glad I did really. Definately been a bit of an eyeopener for me has this whole train of events.

There is something very weird about those numbers though. whp difference is 8bhp which I'd say is a believable difference between 2 RR but 24lbft!

When I get the data from Charlie I'll plot them on the same graphs. I think it may have something to do with how they do the runs, as the torque curves (even with the bonnet up) are quite different shapes to one another.

jmc wrote:I think it may have something to do with how they do the runs, as the torque curves (even with the bonnet up) are quite different shapes to one another.

yes I think you are right. I'd go with the stealth wheel figures as a reference for any future changes.

At least now I have a comparison dataset so I can see how runs from the 2 places compare. Now all I have to start doing is saving for the next round of work

Like pringle crisps once you start..............!

It's hard to say which dyno is telling the truth really. Short of removing the engine and fitting it to an engine dyno, you'll never know the truth!

Personally I'd put the numbers down to be somewhere between the two. Agreed with CTWG60, that 24lb ft difference is curious.

It's not unusual to get very different readings from different rollers. You've got pretty chunky torque there, so simple things like tyre slip will affect the readings. Your bum dyno never lies though. If the car feels faster / better on the road, then it is, simple as

Yeah I would try pushing the reds up to 4 bar first. You'll get ~ 15% more flow, so around 360cc. It's always preferable to use the smallest injector possible for the job and atomisation gets better as pressure increases too, especially at low engine load. I think the G Lader is a fairly linear booster, so there shouldn't be large, sudden fuelling demands like a turbo.

Agree also that 440cc @ 3 bar will give you more scope for future tuning.

ctwg60 wrote:This is why I use Awesome-GTi for comparison of my engine changes. It's expensive at £65 a pop but you can get an idea of how your engine power compares to other cars that have been on the rollers through the website's rolling road day section. My flywheel bhp at chipwizards was something like 230bhp but at awesome it was a more believable 216bhp.

Dude there flucking miles away 4 us.
Or are you offering free lodging for Awesome rolling road days?



@ the end of the day a rolling road is just a tuning aid.
We shouldn't get too caught up with the numbers.
Your car is putting out very healthy figures for the set J.
Santa-pod has opened up again.Maybe try another performance measurement.
The good ol 1/4 mile?!!
You said you felt happy with its road performance,no?

kevhaywire wrote:It's hard to say which dyno is telling the truth really. Short of removing the engine and fitting it to an engine dyno, you'll never know the truth!

Personally I'd put the numbers down to be somewhere between the two. Agreed with CTWG60, that 24lb ft difference is curious.

It's not unusual to get very different readings from different rollers. You've got pretty chunky torque there, so simple things like tyre slip will affect the readings. Your bum dyno never lies though. If the car feels faster / better on the road, then it is, simple as

Yeah I would try pushing the reds up to 4 bar first. You'll get ~ 15% more flow, so around 360cc. It's always preferable to use the smallest injector possible for the job and atomisation gets better as pressure increases too, especially at low engine load. I think the G Lader is a fairly linear booster, so there shouldn't be large, sudden fuelling demands like a turbo.

Agree also that 440cc @ 3 bar will give you more scope for future tuning.

Yeah, I know what you mean - that difference of over 20 lbft does seem like a lot. When I get the raw data through from Charlie, I can plot it all up properly and see how they compare.

I tend not to trust the bum dyno (conversations I thought I would never have ) given that it has misled me before. However it is definately better than when I took it to Stealth which is the main thing.

Thanks for the advice on the fuelling - I will be back for more when I get round to doing anything about it

I seem to recall an article in a magazine regarding rolling road accuracies - Surrey Rolling Road came out as one of the few that were pretty much spot on, with a lot of the others over reading. Can't for the life of me remember where I saw it though now

I know what you mean about the bum dyno being misleading at times. When I first shoved on the GT35R and Schimmel head + a bit of bum dyno tuning on the road, I was adamant the power was roughly 350 crank power. But on the Stealth dyno day, I was amazed to see it was actually 392 crank power. Exceeded my expectations completely.

This supports my argument that once you're over 250hp, you need a SHED load more power to get the same night / day difference you get when going from 100hp to 200hp, because despite having almost 400hp, it still takes a lof of effort to get past tuned up 1.8Ts with approx 270hp. It's like Stereos. A £100 stereo sounds reasonable, but a £1000 stereo is massively better, but a £5000 stereo is only marginally better than the £1000 stereo.

Sorry if that's twaddle, it's just what I've noticed over the years in my own warped reality

Anyway, yep, I've heard the same RE: Surrey. People tend to believe the lower readings as being realistic, but that's not to say Surrey's is actually truthful though. I know Vince did a lot of research and testing when he first installed his rollers as he's also sceptical about some RR figures.

When my 16V Turbo was built, Stealth didn't have a dyno then, so AMD down the road dyno'd it and it made 221hp with 210lb ft on their rollers @ 10.5 psi. But when Stealth got their own rollers, same boost etc, the figure reduced to 205hp with 199lb ft. We all know AMD's rollers are known to be far fetched and I'd tend to agree based on that.

Out of interest, DTA now have hub dynos. You remove the road wheels and bolt on these special jigs with dyno's built in. The advantage is they can handle 1000hp per hub and they remove all the inaccuracies caused by rolling resistance and tyre slip.

if you want a definitive reading, I'd say that's probably a good bet!

Little bit of an update. Went and got my carbon fibre bonnet fitted today down at Performance Trim. Great guys by the way, and can thoroughly recommend them. The bonnet is fab, and it does make the front of the car feel lighter. Having done it I can see why people go down the route of lightening now... Anyway, enough chat, pic...

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I used Mk4 golf washer jets and mounted them under the trailing edge of the bonnet to keep it uncluttered and work better than the original ones. No pics of that at the moment, too cold and dark outside