4722 replies to this topic

[cnrandall]

Great results Nev, can't wait to see this beastie in the flesh. What sort of boost levels did you end up with in the end?

[NickB787]

Fantastic results I will also be glad when yours is fully mapped as I will then be able to get mine on the dyno finally all the hard work which you have put in has paid results, well done

[Nev]

I think Mark said it was producing just under 1.5 bar of boost to get that power, which is not much more than a 'stage 4' engine produces. If I were going to race the car (ie high sustained speeds) I'm fairly sure that building a new exhuast manifold with approx 40mm I/D primaries would make a lot more power at the top end. I reckon doing that would yield another 20 or 30 BHP once over about 6500 revs. Also, I think the inlet manifold needs to be a bit different for over 500 BHP too. Yesterday just handed over my design/ideas to a VX owner who is a welder with a couple of stubs to see what he can make up. I suggested 4 inch long fat tapered runners leading to the ports from a 2 Ltr side entry tapered plenum. This is much the same design that Wayne at Pro-Alloy has on his elise. 400 ft/lb is going to be great fun on the road, am looking forward to that lovely 'pinned in the seat' feeling. I just hope my gearbox can cope, though I doubt it will in the long term. I have a search on eBay for F23s and will keep 1 or more as a spares in my garage as 'disposable items' ! Thanks for the kind words Nick. Maybe we will meet in 'battle' on the track one day

Edited by Nev, 06 August 2011 - 10:10 AM.

[Nev]

Nipper is ready for collection - hoorah !

Mark has kindly emailed me the dyno plot which I have attempted to paste below. It looks good to me, fairly flat torque line, though it does drop off a bit more than I was hoping in the higher revs. I suspect this is due to the restriction of the exhaust manifold and perhaps the inlet manifold. There is also a noticable blip at 7300 revs, probably some sort of resonance issue in the breathing, once again possibly exhaust manifold related.



[mod edit to rehost image]

[Duncan VXR]

Nev mail us a copy cant see anything Let us know how it goes collecting, hope its dry! DG

[VXT Tim]

Great news, can't see the graph.

[techieboy]

Now that's a journey to North Walsham you won't mind making.

[StealthVXT]

Great news, can't see the graph.

Right click on the little icon (where the image should be) and click open in new tab. and bobs your mothers brother

Nev, looks awesome! That is going to be some beast!

Ignore my comments now as the mods have fixed it...

Edited by StealthVXT, 10 August 2011 - 08:21 AM.

[Duncan VXR]

Nev looks good!!!!, def drop at the top end which is a shame but sure some further playing will smooth it out, you will have wet your pants by 6k anyway Got to be happy with outcome and sure Steve will be happy to see the engine he built did what was required of it Cant wait to get some feedback from you on how it drives DG

[spuk87]

Good news . Looks like lag city until 4-4.5k revs though, but with 8k rev limit you should be able to keep out of that area when you are actually going for it.

[StealthVXT]

Good news .

Looks like lag city until 4-4.5k revs though, but with 8k rev limit you should be able to keep out of that area when you are actually going for it.

Look at the graph and even his lag is producing more than a standard VXT on full power! WOW

[VXT Tim]

torque jumps 150 lbft in 500 revs You are going to need to be awake (and with all 4 wheels pointing in the same direction )

[NickB787]

well done thats a pretty good looking line, think dry driving for a while to get used to it, take it easy. About that drag some time, no problem but you must promise not to go over 4500rpm

[Judderman]

Great news Nev, cant wait to hear about the drive home (make sure you take it easy with all those horses to foot)

does this conclude your epic blog or is this just the beginning

[VXT Tim]

Sure the blog will continue with aero parts...... wheelie bars

[Seb.F]

Bloody hell that's an insane onset of power! You're going to need to be caffeine fuelled every time you drive it!!

[steveboyslim]

Good news .

Looks like lag city until 4-4.5k revs though, but with 8k rev limit you should be able to keep out of that area when you are actually going for it.

Given that there is not much to compare power curves for this turbo with, it is similar to the graph shown at http://www.vauxhall-...rbo-t16029.html

Steve

[alanoo]

I respect the build a lot, but I must say I do not like this kind of power delivery at all. Considering the torque is still gigantic at the rev limit, wouldn't playing with the cam timing a bit move the torque curve earlier in the rpm range ? Ultimately, I wonder how much you could make it better with a GTX or an EFR ...

[steveboyslim]

I respect the build a lot, but I must say I do not like this kind of power delivery at all.

Considering the torque is still gigantic at the rev limit, wouldn't playing with the cam timing a bit move the torque curve earlier in the rpm range ?

Ultimately, I wonder how much you could make it better with a GTX or an EFR ...

That engine uses a GTX turbo.
Cam timming may help, but at the time of the build suitable vernier cam pulleys were not available to trigger the cam sensor.
There was also a limit in the mapping cost so no timming adjustments were tried (I am sure Nev would test your theory if you are willing to pay for the mapping time)
The torque and power curves are very similar to the graph shown from a Mitsubishi evo using the same GTX turbo (the vauxsport iink)

Steve

PS there has been rumors of problems with EFR tubos

[alanoo]

Arf, I feel sorry, I thought it was a normal GT3071 but I realise I was wrong when I look at the excellent Nev's build blog. I can understand the map/dyno time/cost limit too, as I only know too much how these can be costly