82 replies to this topic

[manus]

Might go for the Hewland dogbox option inside F23 housing. Was is a one-off project or is it a product you can still order?

[manus]

First twin scroll Z20?

Turbo needed to go up that high because the dry-sump oil-pump will be taking its 'normal' place.
(And the pump is there because a drive shaft is on the other side.)

This gives new options for a chargecooler above the gearbox and having a reduced-length intake tube

Edited by manus, 02 January 2013 - 04:36 PM.

[siztenboots]

1+4 on the first , 2+3 on the second I know the theory of twins is to have a matched manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy.

[siztenboots]

from a thread, a while back http://www.vx220.org...s-tial-garrett/

[manus]

1+4 on the first , 2+3 on the second

I know the theory of twins is to have a matched manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy.

Yes, that's the concept.....However fuel economy was not on my list

from a thread, a while back

http://www.vx220.org...s-tial-garrett/

Interesting discussion. Is there a running Z20 twin scroll engine somewhere (with Dyno graph)? I'll start mine in 2 to 8 weeks, pending gearbox and other works.
The small connector at the turbo is an RPM sensor. That will give a nice idea about spool-up times on the graphs.

Edited by manus, 02 January 2013 - 04:51 PM.

[Nev]

I don't know of a Z20LET with a twin scroll turbo myself, I think you might well be the first person to try. From what I understand, the gains from twin scrolling are hard to get right, but best of luck to you. If you want smooth scrolling, then try eliminating the Pierburg valve and run a direct vacuum signal pipe from the manifold to the wastegate. Then you can either install a wastegate spring to set the max boost pressure, or install a MBC in the middle of the vac pipe and allow yourself to adjust it from inside the cabin. I've done this and it's one of the best (and cheapest mods) you can do for the car IMO. Dry sumping is nice and serious, so I gues you plan to race/track the car a lot.

Edited by Nev, 11 January 2013 - 02:35 PM.

[manus]

Update. Hewland dogbox is in the car now. Top speed will be limited to 286km/hr but I can live with that. Freno carbon brakes will be mounted soon (2kg including bell). But first we focus on getting the car on the road for a 1/8 mile sprint end of this month....

 

Below some images of the progress made.

 

Without the rear clam. Geo setup yet to be done.

 

The intake manifold came from a Subaru but is heavily modified. Chargecooler now on the left to make a nice short route from turbo to cylinders. Throttle body comes from BMW or MB, not sure. Injectors 850ccm.

 

Dash will have a lot of displays. Work in progress...

New aggressive cams

Nitron uplinks and 4130 lightweight wishbones. (And some Porsche part, to get some cool air to the brakes.)

Fronts

Nice small (but strong) altenator

Airbox. The 2 curves between LMM and turbo in the pipe are there deliberate, to protect the LMM.

Oil filter and cooler now on the right

Cut-off switch and battery mounting. This 3.4kg unit is strong enough to do the job.

 

Edited by manus, 15 May 2013 - 08:44 PM.

[manus]

Nice and short and not too many corners in there.

 

 

[manus]

[font="calibri;"]Some other info[/font]

 

[font="calibri;"]Unsprung weight will be almost lowest possible.[/font]

[font="calibri;"]The wishbones weights are as follows[/font]

[font="calibri;"]Standard VX / Exige Upper Wishbone with balljoint and inner bushes 3586g  - 4130 wishbone with inner and outer bearings - 1878g[/font]

[font="calibri;"]Standard VX / Exige Lower 1557g - 4130 wishbone with inner and outer bearings 902g[/font]

[font="calibri;"]Standard VX / Exige Toe-link  1063g - 4130 tube with inserts and two rod ends 288g[/font]

[font="calibri;"]Total weight of rear arms before 12.4kg now 6.1kg.[/font]

 

[font="calibri;"]Disks will go down from 5.5kg to 2.08 kg (incl. bells)[/font]

 

[font="calibri;"]Uprights I forgot, think it was 4.8kg in total for all wheels.[/font]

 

 

[font="calibri;"]Number of pony's we'll find out next week on the Dyno. (target is 560bhp)[/font]

[font="calibri;"]Total weight we'll measure when all is done. (target is below 850kg)[/font]

[font="calibri;"]First gear will go to 108km/hr (at 8500rpm). [/font]

[font="calibri;"]Default choice of tires will be Yokohama 048's 225/45 R17  295/30 R18[/font]

[font="calibri;"]Sprintrace will be done on Mickey Thompson drag tires or super-soft slicks. But main purpose for this car remains proper LOT lap times with lousy driver [/font] 

 

 

[font="calibri;"]More details and pictures (Dutch text, sorry for that) on: [/font][font="calibri;"][color=rgb(0,0,255);]http://www.speedsterclub.nl/forum/viewtopic.php?f=10&t=2619&start=1185[/color][/font]

 

[font="arial, helvetica, sans-serif;"] [/font]

[font="arial, helvetica, sans-serif;"] [/font]

[font="arial, helvetica, sans-serif;"] [/font]

 

[jameso]

Awesome build

[rob999]

Top top stuff. How long til it's all back together?

[manus]

Top top stuff. How long til it's all back together?

About 3 weeks from now. Fingers crossed...

 

We're almost at the final phase of the project. Hoping to get some basic engine-set-up and the car on its wheels end of next week. Then the car needs its yearly APK (MOT) to keep it road-legal and insured. If it passes, some on-road fine-tuning of the engine. The workshop (V-max.de) will take her to the Oscherleben 1/8 mile sprintrace end of the month. When all that is done the carbon brakes are to be installed and I'll take her to a track to see if the car needs more adjustments.

[manus]

Dry sumping is nice and serious, so I gues you plan to race/track the car a lot.

[color=rgb(34,34,34);font-family:Arial, 'sans-serif';font-size:10.5pt;]Yes, track days, track days and more track days![/color]

[color=rgb(34,34,34);font-family:Arial, 'sans-serif';font-size:10.5pt;]I was not so much worried for oil starvation in corners. The problem for this engine would be that the (small) crankshaft bearings need more bars to keep a steady oil-film in place, given the projected workload. The dry sump is expected to give 8.5bar, which should be enough. (That would be too much for the valve-lifters but we've changed those to fixed ones.) And there are other advantages (weight distribution, engine vacuum and crankshaft not having to plow through a pool of oil)[/color]

[color=rgb(34,34,34);font-family:Arial, 'sans-serif';font-size:10.5pt;]The engine as we build it should be fit to run up to 750bhp. But I do not want to go that far....[/color]

[Nev]

I reckon 750 BHP in a lotus chassis would be mostly unsuable. Even real 560 BHP is a hell of a lot.

 

Amazing build BTW. Who is doing the work ?

[smiley]

Amazing build BTW. Who is doing the work ?

 

http://www.vmax.de/

 

Edited by smiley, 16 May 2013 - 03:38 PM.

[manus]

A bit of a set-back last week. One of the (brand new) valves cracked and fell in the combustion room.... destroyed the engine .... We need to rebuild completely.  

Still working out how this could have happened, need test/check all other valves and inspect for collateral damages.... Will take couple of weeks to get back to where we were

[techieboy]

 

Ouch. Can't imagine how soul destroying that would be.

[chris_uk]

I reckon 750 BHP in a lotus chassis would be mostly unsuable. Even real 560 BHP is a hell of a lot.   Amazing build BTW. Who is doing the work ?

Aslong as you have adequate downforce, tyre width and compounds, traction control etc etc i see no issue. Scuffs manages ok and they play in that reigion of power.. Ill just add the more the power delivery is linear the more useable ot will be.

Edited by chris_uk, 22 May 2013 - 08:58 AM.

[Nev]

Jesus, terrible news. Was it a manufacturing defect? Usually valves are made in 2 pieces and I suppose the poppet end may have detached from the stem due to poor fusion of the 2 parts? Those cams you have really do have long lobes, very visible from the pics. I have to say it again, that looks like one of the most impressive VX220/Elise chassis build I've ever seen. Dare I ask how much you've spent on the upgrades please?

Edited by Nev, 22 May 2013 - 09:21 AM.

[Scuffers]

 

I reckon 750 BHP in a lotus chassis would be mostly unsuable. Even real 560 BHP is a hell of a lot.   Amazing build BTW. Who is doing the work ?

Aslong as you have adequate downforce, tyre width and compounds, traction control etc etc i see no issue. Scuffs manages ok and they play in that reigion of power.. Ill just add the more the power delivery is linear the more useable ot will be.

 

this.

 

power is only scary when it's un-manageable...

 

the primary reason for going to compound charged route with Jamie's car was to be able to keep it drive-able, something that plonking a huge turbo on a small engine is never going to be great at.

 

the results are better than I expected in terms of drive-ability, it really is a pussycat to drive, all be it a bloody fast pussycat!