Recently, i had my MOT which flagged up an issue with my 'V' Band adapter. The adapter was loose, meaning there was quite a sizeable gap, where exhaust gasses could escape/air get sucked in. I have since fixed this, but as the hole was so close to the lambda i thought it may be wise to get the car rolling roaded to make sure everything is tickety boo before i spank it round Spa next weekend.

I went to this place, http://www.motoscope.co.uk/ , which is in Northallerton, N. Yorkshire.

It was a Dastek Rolling Road, and i was very impressed with the setup at the place, and the service was excellent.

Also cheap, only £45 for the 4 power runs i got, he said it was only £35 a car for club days, if anyone is interested in future?

Anyway, here are the results;



Interestingly it made more power at low boost - 305bhp at about 1.2bar.
301 bhp at 1.4bar but with a load more torque.

I'm not totally convinced by the boost graph he has given, its a lot higher than what my Apexi reads, however there seemed to be a lot of load on the rollers, taking a good 20-30 secs to go through the revs.

Interested to hear peoples comments

Thank you

I want 300bhp, what mods mate

After 5000 rpm the boost falls very fast. Is that normal APEXi behaviour

No it isn't normal Apexi behaviour, looking at my last Rolling road ;
Which was about a month ago, the boost profile is completely different. I wonder if it could have anything to do with the 'V' Band being loose?

My engine mods are;

FMIC
SIP
Forge dv006
Apexi boost controller
GT28R turbo
Aquamist - which i dont think works

Well you are back in the 300 club, like I said a different set of rollers on a different day

The boost drop is very odd indeed, I assume you haven't observed this behaviour on the road? The last rolling road boost profile was normal and the same as on the road. I am guessing you haven't changed anything since I setup the Apexi, if so then there is absolutely no reason for it to drop like that, an anomaly perhaps. It's a shame as I think it would have made more power if it had held the boost and tailed off naturally.

Anyway, you are all set for Spa, stick it on the higher boost and have some fun as it's all looking good

No not changed anything Leighton. I wouldn't know how to do it anyway! Feels just like it always has. I'm really enjoying the car at the moment, lets hope it stays that way. Cheers for your help, matt

good peak figures for a GT28R running the V-band and standard head.

The higher boost run not making any more power would indicate your setup can't flow any more than a shade over 300bhp - which is typical of that turbo.

Dont over analyse the graphs too much - if it feels good on the road and is fuelling well then go and enjoy Spa.

the boost tailing could be losing you upto 10bhp though.

Ive had issues with apexi's in the past where the spring in the solenoid opens up too large, and causing them to drop boost very early.

You can flip the spring around and it solves it, until the other end does the same thing.

Is it possible to order a new spring if this is the case?

I think the thing to do, is record the boost profile with the Apexi. If the boost curve looks ok on there, i'll be happy and just put it down to a spurious reading.

Just got to work out how to do it!

Thanks all

Apexi are no longer, they folded last year i believe, hence the sheer lack of AVCR's for sale on ebay.

You can buy a new spring from most fastener/fixing shops. undothe 2 screws and see if one end has enlarged. If so just flip it over.

Blinding, cheers Rog. Might be able to nick one out of my Biro eh?

How does the v-band adaptor look like?

A bit like this ; http://www.aptuning.net/V_Band_Adapter_GT25_GT28_GT307X_WG_Series_p/atp-vvw-023.htm

Basically it is a plate with a hole in it, that bolts to the exhaust side of the turbo, and allows you to connect to the downpipe with the original clamp

Done a couple of runs recording the boost profile on the Apexi, everything looks alright to me.
Must have been a dicky sensor on the Rolling Road's boost thingy.
Video

You forgot the decat om you list of mods Matt!

How did you find the fella's there? I tried to arrange a rr day there a couple of years back but had zero interest.

Took a trip myself anyway and they had alot of interesting rallying machinery.

You can tell that the boost did actually drop as the torque drops sharply at the same time loosing you power. Why it happened is another question but as long as it's fine on the road then that's what counts.

Phil, he was a top guy actually, seemed keen to get a RR day. He didn't strike me as particually computer competent, which may be why he didn't get back to you.
I sent an email which he didn't reply to, but when i rang he was more than helpful.

Leighton, just looking at the graphs again, do you think the boost anomoly (spelling?) could be to do with the RR having more load on it than the car would see on the road, hence the boost going right up to about 1.5bar, then sorting itself out, and levelling to around 1.2 bar at redline?

there is more load on the road (I'm a poet and I know it )

It can be adjusted though can't it? on a rolling road i mean. So if he had it on the highest load setting, it may be more than road?
Reason i ask is because, the run took considerably longer than any of the other rollers i have been on.
I have been on a rolling road, which didn't have enough load on and the run took about 6 seconds, and i created less peak boost.
So i was guessing that, because these runs lasted about 30secs, there would be more load, which might mean more boost.
Just clutching at straws really, correct me if i'm wrong

i'm not an expert on RR's. but maybe they used a higher gear. it shows on your printout they used 4th. what gear was used for other runs you've had?

Usually 4th gear. I'm not really concerned about this issue because it works fine on road, just interested as to why?

A power run won't normally load the car the same as the road. If you think about how long it would take to go from 1500rpm to 7000rpm in 4th on the road, well it would be a long time! Some dynos will provide no load except the rolling mass of the drum i.e. inertia, others will set a ramp rate which will load it enough to simulate road conditions better. You can load the dyno beyond the road i.e. full throttle at 4000rpms and it will simply hold it there which is often usefull for mapping certain load/rpm sites. It can't do it indefinately i.e. seconds or a minute, as the heat generated in the retarders is immense and of course it depends on how much torque it is fighting against.