JMC's 1.9l G60

nice, im liking your front bumper idea, not seen that before

Do you think there is less understeer with the lighter bonnet or does it feel different in some other way? Any chance of a pic on the underside and the fixtures and fittings?

I'll get some pics of the underside sorted later mate CTW. Fixtures and fittings were all transfered over from the standard VAG bonnet.

I was driving back yesterday and it definately felt like there was less weight out over the front. It felt more responsive on the steering, and braking. Now I'm sure some of that will be because of the grin factor, but I am now a firm believer in the 'add lightness' philosophy.

EDIT - now with a pic of the underside....

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Looks good! Did they make holes to refit the little twist-in rubber feet at the front of the bonnet. good to hear there is a performance advantage that you can notice on the road. Something for me to spend money on in the future, maybe

Is it any more noisy without the bonnet insulation?

The bonnet was made with fittings in it for anything that needs screwing back into it. Not sure about the little rubber feet though - don't remember seeing those??

I haven't noticed any extra noise within the car, but then mine is pretty noisy anyway

the twist in rubbers go on the slam panel, not the bonnet

Flusted wrote:the twist in rubbers go on the slam panel, not the bonnet

That might be why I don't remember seeing them in the bonnet then

Flusted wrote:the twist in rubbers go on the slam panel, not the bonnet

Oh yeah!

I'm all for lightness too, so long as it's removed from the right areas and the front end is one of them

After gutting out the rear of my car and moving all the chargecooler tank, battery etc between the axles, I was a bit dissapointed to be honest. Barely felt any different at all, despite shedding ~100kg.

I'm pretty sure a VR6 would benefit from a carbon bonnet, but I can't justify £500+ on one at the moment, especially when more acceleration and better handling are all but a couple of thumbwheel turns away

Did the MK4 washers fit under the bonnet OK? I'm not sure how they fit on tbh. I might just put some on the metal bonnet anyway as the Corrado squirters are a bit piss poor

Yeah, the mk4 washers actually fit like a dream Kev. Mike wasn't too sure when I brought them out of the bag. It require some cutting of the support section on the underside - on mines thats just fibre glass so I'm not too bothered about that.

Here's how they look....
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Mike (well Lee actually) cut squares in the fibreglass so they'd be a really tight fit. Basically once they were in there, one of them needed a thin shim to make sure it was pointing in the right direction. Other than that, nothing to it. I have kept my old washers as I wanted the electrical connections off them (the new ones are heated too, but different connectors).

Good work Jonathan. So you can feel the difference on the road then? I'd imagine that the centre of gravity at the front has probably lowered a little with the loss of that weight up top. Does it a feel any more nimble into the corners and do you get less body roll? Does it feel any quicker through the gears as well?

Questions questions questions

It feels better on the twisty stuff (easier to turn in, and just, wel sprightlier). I haven't noticed less body roll though, or through the gears.

Just fitted a 3.5bar fuel pressure reg today. Car runs fine, but I think I'll have to get it dyno'd again to see whether it's helped with the fuelling at the top end.

Just got back from being home (up norf). While I was up there I went to JP Exhausts in Macclesfield and had a 2.5 system with 3 boxes made up . Looks fab, sounds great - not much lowder than my old one, and actually if anything a little quieter on the motorway. I got the usual H&S spiel while there about not being allowed in the workshop while they made it, but they took pity on me as I was bored in waiting room, and they showed me round their laser cutting system. Which by the way if you want anything doing is excellent, an they are looking for small one off jobs to fit in around their other work. Anyway, enough chat - pics.
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Nice. Whens the RR Day!

I think for the RR I'll put my 3 bar fuel pressure reg and opened out air box back on - that way I'll be able to see a 'like for like' comparison with my old exhaust system (at the moment I am running 3.5bar fuel pressure reg and an original uncut airbox). I'll see if I can get some time with Charlie next week.

Looks good Jonathan. Welds look neat too! How does it feel? Do you think it's made a difference?

Yes it does feel to have made a difference - although my 'butt' dyno has been misled before. They did a really neat job on it, and it should be so much freer flowing than the old one.

Hmmmm, interesting. Just got back from SRR and the dyno. The new exhaust is making less power than the old restrictive one, and not just 1 or 2 bhp less but about 10-12. To be fair the previous dyno runs were in the dead of winter when it was 1 degree C as opposed to a warm sticky afternoon which it was today, but even so a bit depressing. I suppose I have to think of it in terms of 'the new exhaust will allow it to be set up better' rather than just a 'swap it and expect it to work' mentality.

Also did a stock vs cut airbox run on the G60 so I'll get that sorted out and up later when I have time. Basic conclusion stock air box - poor breathing, cut airbox - good breathing.

blimey.
Makes you wonder just how much air does an engine have to pump b4 a standard exhaust becomes a restriction...

Hmmm.
I wonder if more people did what you did after fitting a new exhaust if they wouldn't get similar results.Shows how hard it is for the average joe to match components so they all work together.
Well I applaud the way you are testing everything and not just deluding yourself.

Sorry you were depressed at the results, Jonathan. You will know that the pressure difference of the intake is quite large when comparing winter to a spring day in the late teens! So, chin up I say

did u gain/loose torque Jonathan?

Cheers guys. I'll have to wait until Charlie sends through the results by email before I can check properly against the old results, especially for the torque curve.

It is a bit however I can understand why - the system was mapped when it was really really cold weather, and the last runs were done then too. Now it is warmer and with less boost its running rich. Just goes to show how setups can be so dependant on conditions. Also it was setup with a specific gas flow from the previous exhaust, expecting a certain back pressure - the mapping even for this exhaust alone is probably very different than the old one. I get the feeling that the new exhaust will be a godsend when I go for the 65mm pulley, and eventually the nitrous.

The bigger shock for me was the difference between my cut air box and the original box. I was concerned with the original box that the very small air gap between the opening in the airbox and back of the headlight would restrict the flow hugely. It turns out it does - when I get home tomorrow I'll scan the printouts and let you know those. I can understand the big differences JezzaG60 was seeing between the different air intake systems now.

Here you go folks the Dyno plots. Bit difficult to read as everything is close together, however 054 is the cut air box and 056 is the original airbox (same filter). Quite a large change across the board, but especially from 4500 onwards.
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Interestingly 061 was a run I did with and ISV I bought of eBay (along with my cut airbox) as mine is leaking slightly. Made more up to about 5200 then suddenly flattened out and bled boost. I think I need to understand more about ISVs work and what they are doing at different points in the RPM/throttle position sequence as this puzzles me .

roughly guesstimating on that scale, looks like the new intake is gaining 10ish lbft at 6000rpm! Sounds good to me!

Probably unclear from my post - the cut air box is what have been running for a while now. I included the uncut original airbox in the test as well as I wanted to see what benefits (if any) I was getting over using an uncut box. As you can see the cut box I'm running gives a big benefit over the original setup. Very similar to what JezzaG60 was seeing with his test from memory.

More intrigued by the ISV now - wonder what is going on there. Very tempted to just put an ISV reroute in and just not worry about it venting.