Ex works Vauxhall Astra BTCC track car

[VX BlackRat]

It’s been a while - sorry for the slow updates but I’ve been carefully considering all the engine options for use as a track car.
It makes sense to keep the original engine architecture (GM L850) so that it installs with the original mounts & is compatible with the Xtrac sequential gearbox. With this in mind I found 4 options….

1. Use the existing Sodemo 2.0NA unit, I spoke with Swindon engines (they can fully support this engine) they reckon £15k to refresh the engine and it’s will last approx 500 race mls before rebuild.

2. Use a current BTCC 2.0 turbo engine, these are about 370 bhp & only need refreshing each season and start at £6k for a used unit.

3. Use a Saab B207 2.0 turbo and 'off the shelf' performance parts, engines are only £1k new!!

4. Build myself a 2.4NA engine raiding the Vauxhall parts bin & use aftermarket tuning parts.

Option 1 – No way, too expensive for a track car. I will save the original so that it meets historic touring car technical regs should I want to race it in the future.

Options 2&3 – Although they will mount to gearbox, the rev limit is lower (7k) and the torque is much higher (400NM) than the original. The max speed for longest available Xtrac ratio @7k is only 125mph & the gearbox is only rated to 300NM.

Option 4 – Reasonable build cost (£3-4k), estimated power similar to Sodemo original, gearbox will handle the torque and it should rev to 8k. So should be similar to drive to the original with hopefully much more life. It will have the same head design therefore will mount to the original exhaust / intake / fuel / ECU systems. If it ever goes bang, I can fix it.

So decided on option 4 and am now sourcing parts to build myself a 2.4NA engine 

Gearbox is going to a specialist to be stripped & checked next week.

Any recommendations for somebody to service the shocks?

[VX BlackRat]

Yep, this isn't going anywhere other than under the bench until needed. i.e. when tech regs require it.


Perhaps this one day...... http://www.supertcc.com/2-litre-touring--st4.html

Walk around vid of the PT on the subframe (dullest thing on youtube according to my 10yr old daughter)

https://www.youtube.com/watch?v=OsfqZyZY6ns

[VX BlackRat]

poppopbangbang said:

If you put some less aggresive cams in that (i.e. ones where the lobe stays in contact with what it's driving for the full rotation - S2000 only specified the max lift at the cam not the max lift that the valve ended up at) and turned the revs down a touch it would do WAY more than 500 miles and still make 250bhp odd.

Is this on the Sodemo ECU or a Pectel? I might still have some of the configs and maps for it somewhere......

It's a BTC-T spec with a EFI type ECU as per TOCA regs at the time. You wouldn't have maps for this would you??? That would be awesome.
I'm told that the cams are very aggressive (square) I've got newman cams lined up to measure the profiles and make me something less so. The 2.4 bottom end I'm getting from the states will marry to any L850 head including original (lost foam cast) and the saab B207 (sand cast). Only cost buttons too.

[VX BlackRat]

poppopbangbang said:

The reason for the square cams is to get around the maximum valve lift specified in the regulations. If the regs say 12mm lift and you grind your cam so when measured it has a lift of 11.99mm then you're legal, however if you design this cam with a hugely aggresive ramp angle and pair it with a valve spring of a suitable rate (this is the bit which takes a lot of work) then during valve opening events the valve and it's associated valve train bits leave the end of the cam due to the very high ramp angle which gets you precious extra valve lift over and above what the cam measures at. The downside is you have fairly large wear on cam and followers and likely valve life and valve seat life is reduced as the valve can clatter back into the seat rather than being returned back to the seat by the cam lobe in a controlled way in extreme cases (although really your ramp out wouldn't be that harsh in practice). If you have a series with spec max revs and valve lift but OEM budgets then it's a good option to explore and many used it in BTCC at various points.

I won't have the EFI maps unfortunately but it's likely you can read the maps that are in there off the chip if the current ECU isn't on an open developer and then with a bit of work get these into a standard spec open EFI ecu so you have an ECU that plugs right in but you can access. If it's the one with a big red TOCA on the front and a single Amphenol connector then it's a Euro 6 - have you tried talking to it with just the boggo EFI CAN interface to see if it's open?

Fantastic info. thanks! Love finding out about the work-around tricks of the day.

You put up a really strong argument for running the Sodemo but I think I’m going to stick with the 2.4NA build, I currently don’t have anywhere near the funds for the initial engine refresh of the Sodemo and if I did it would still carry some risk running it….I’d hate to blow something so valuable just doing track days. I’ve already got some parts for the 2.4 build too.

I’m essentially building a replica Sodemo head for my 2.4NA build with less aggressive cams using a better cast Saab head. This will be skimmed & ported by a specialist (not decided who yet), can’t see why I shouldn’t see similar flow rates? The std valves are just shy (-0.15mm) of the tech reg sizes so will probably leave them alone or consider custom later. Up the spring rates to allow extra rpm. Bolt up a forged & balanced 2.4 bottom end.

The ECU is a Euro 6, I don’t have a cable, they are quite pricy so was looking for a tuner to sort all of that when it goes for set up on a dyno. Do you know somebody local (I’m in Beds too) who could do this?

Cheers!

[VX BlackRat]

Thanks for the recommendations Tim, I've got Steve @ SGS Transmissions just outside Aylesbury lined up to inspect the Xtrac.They can also make any ratios should I need to adjust due to engine running a lower (8k vs 8.5k) RPM.

The engine swap will be completely reversible - future value / going racing in original spec will be preserved.

Hit a bit of a snag on the crank to flywheel compatibility though. The Sodemo has a 8 bolt fixing, the 2.4NA crank I'm planning to use has a 6, so mulling over potential solutions, currently thinking custom flywheel will be best option.

[VX BlackRat]

Cheers Mickey, just sent them a email.
Was yours a custom fly? What was the cost?

[VX BlackRat]

Cheers mate, Helix can reverse engineer me a flywheel, just waiting on a price.

Meanwhile SGS have just opened up the Xtrac, initial look at the internals seem to be in good nick.

[VX BlackRat]

Hooked up with the Xtrac lads at the last BTCC meet at Silverstone, they were really helpful. I've got the Xtrac 406 manual with all the exploded views & TSB's - but not sure they will be happy if I post them here.

Table below shows component life in Km's, apparently the components were too good and they didn't sell anywhere near the volume needed from a business POV supporting TOCA. Good news for me though.

[VX BlackRat]

Awesome! - you must have deep pockets keeping the Sodemo running!!!
How much do you use it? Where are you getting replacement parts?

[VX BlackRat]

Chuffing cold in the garage ATM so not too much physical activity but I’ve been specifying and getting custom engine parts made. There’s a quite a few tuning company’s in the states that are suppling parts. Luckly I’ve got access to the original engineering drawings for the OEM stuff so it’s been quite easy to customize these for my 2.4 NA race engine. Main spec….

Molnar forged con rods
Wiseco lightweight forged pistons – 12:1CR so should be OK for super unleaded
Bottom end will be balanced
Supertech o/s valves and uprated valve springs
Cylinder head port and polish - I’m going to give this ago myself.
Haven’t decided on the final camshaft profile yet, there are quite a few to choose from e.g. comp cams but could also get a custom grind. The inlet cam also needs to interface with the cam position sensor & drive the power steering pump so it’s not too straight forward.
Custom flywheel has been fabricated by TTV Racing and I’m really impressed by their work, hopefully I’ve measured the timing lobes to TDC correctly!….








Gearbox is having a new 6th gear made to suit the lower rev range. Should be ready later this month.
Clutch is at AP getting a refurb
ECU is going to OBR to get new internal battery and ‘safe’ base map.

All being well I’m targeting June for initial shakedown

[VX BlackRat]

AP have just condemned the clutch, apparently beyond economic repair. It’s a sintered twin plate 140mm unit rather than a carbon / carbon (£5k ouch!) that some of the engines were running.
Full replacement from AP is just shy of £1k. 6-8 weeks lead time, these things may be quick on track but getting parts is anything but....

[VX BlackRat]

.......should have measured the engine installation properly!



Still waiting for pistons - any day now....come on Wiesco!!

[VX BlackRat]

snowen250 said:

andy97 said:

Is this a sister car?

https://www.racecarsdirect.com/Advert/Details/8558...

I believe that to be this car here:

http://www.touringcarregister.com/register/200/

and here it is before in happier days:

http://www.touringcarregister.com/register/254/

Simon

The roll cage is a different design so I doubt it's a Triple eight built chassis..

[VX BlackRat]

Forged pistons are ready. I'm surprised that the weight would be more than 50gr more than the cast OEM pistons.
Extra mass for the higher CR design & deeper valve pockets depth I guess?

[VX BlackRat]

Sorry it’s been a while there’s been a few delays on this and that but I now have a running car with the 2.4NA engine build

Pistons and rods all balanced to 0.1g with rings gapped for application.....


Installed into block....


New AP twin plate BTCC spec clutch....


Engine build complete......


The most horse power this trailer has ever had in it......


Ready to load into car.....


Loaded in the car first fire of the engine, this was scary - like being at birth of children scary....
https://www.youtube.com/edit?ar=1&o=U&vide...

and a little test run - nice driving bro ......
https://www.youtube.com/edit?ar=1&o=U&vide...

[VX BlackRat]

Oops! Yes these are the links.....

playalistic said:

https://www.youtube.com/watch?v=e44poFpDo3I
https://www.youtube.com/watch?v=mzidQXjQcAo
https://www.youtube.com/watch?v=UYQ5UAwbtZ0

[VX BlackRat]

I'd love to think ive built a race engine but really it's a modified road engine. Hope I haven't done any damage? It's run for about 30mins with 2 real heat cycles, upto 85c water temp. Oil pressure good.
I kept all the oil clearances oem, I've retained the hydraulic lifters for now, hoping this will help bed in cams. The bores didn't need honing but the rings are new but aren't too racy.

It's running a safe map for now until I've done a full shakedown / running in on track, then plan rolling road session to optimise map with solid lifters and adjustable cam gears.

[VX BlackRat]

Thurbs said:

It is not about damage and I am sure there is no damage done. Race engine running in is about trying to maximise the power and longevity of the engine in a race situation. This is especially important with the piston rings where you want a nice seal with the cylinder and you only really achieve this by placing load on them (hence the not idle rule).

When you need to warm it up, progressively rev it until warm but again when you do leave the pits remember the diff and gearbox is cold (this is why you see teams put a car on stands and warm up the car in gear).

When on track or the rolling road (the best way to run in a engine) then start of with light load and don't labour, progressively moving up to full power after about an hour. If your car hasn't been mapped, I would get the mappers to run it in for you and then map the car. It will be much easier for you and it is what I have done in the past.

Your engine builder will be able to advise you the best and should have given you strict instructions on how to run the engine in when they delivered it to you.

Finally, the only difference between road and race is how expensive the bits are. The run in process should be the same just with different chances of seeing the bits inside again anytime soon!

OK thanks, not too concerned about loosing a few bhp as not racing anyone, main objective is to have a useable solution I.e no long winded warm up procedure, get to track and get going with minimum bother. Good point about warming up the gearbox though.

I am the engine builder so I'll give myself a good talking too regarding run in

Edited by VX BlackRat on Wednesday 21st November 21:04

[VX BlackRat]

Bright Halo said:

This is all coming together nicely!
What sort of power are you expecting out of it?

Cheers!
I hear that the original 2.0l engines were putting out 270-280 bhp @ 8.5k rpm.
with the extra 20% capacity of the new 2.4l build but with lower 7.5k rpm limit and less aggressive cams but larger valves I hope to be near the original.

[VX BlackRat]

scottos said:

Wow, what an awesome thread!

The competition engine builders i assist at sometimes does quite a lot of those engines, normally for drag racing where the guys using them are doing 1000+hp, this tends to mean fitting darton sleeves, or for lower power applications, machining out the water ways at the top and pressing in a machined deck plate.

They also run some old touring cars, Mazda 323 super tourer, old group a 635csi etc.

They are quite overlooked engines considering the base engine can be found in a Frontera! Im glad there's people buying and running cars like this, keep it up!

Thanks guys, yeah this is a much overlooked engine – Swindon Engines still supply a turbo version to some of the current BTCC race teams. Mine is a hybrid of 2 engines; a Antara 2.4 bottom end with Saab B207 top end. It’s been my first ever engine build and I’ve learnt a heck of a lot about performance engines in a year, did most of it myself except the head machine work so was really pleased when it fired up for the very first time…..

https://www.youtube.com/watch?v=kdZg9ubWKHo

I’m a sponge for any more info you have on them…I’m already thinking of a Gen 2 with titanium internals short stroke Darton sleeve version.