91 replies to this topic

[Rosssco]

The idea of the V8 is very nice, but the compact V6 would be so much easier to do and there is scope for a huge amount of tuning beyond the easy to achieve 380Bhp. If it was felt that it was needed.

Rich, if V6 is an optional route (although V8 is still the Daddy..), I've looked at the Nissan VQ35 engines (primarily used in the 350Z in this country), and although probably considered a bit of a left-field choice over here, they have a relatively large aftermarket following in the US, so quite a few FI options available. N/A form they chuck out between 270-310 bhp / 265 lb/ft standard (dependant on version), and are a 160-170kg engine in the spec you'd looking to use them. There is N/A tuning potential also, but this can get very expensive for relatively little gain. It wouldn't really be an 'upgrade' for a stage 2+ tubby owner as such, in pure performance terms, but it does sound very sweet...

Just another option I suppose..

[Nev]

The H1 V8 is a cracker.............but it is so overpriced. Not because it is so great, but because there are so few.
I have been quoted £45K for one....ha h ah a.......
Too rich for my wallet.

I know where you can get them for £21k . Still that is a LOT for an engine that will likely need major refreshes quite regularily, too much for a road car

Edited by Nev, 14 June 2012 - 10:24 AM.

[14500rpm]

On the engine front what about a 1UZFE Toyota/Lexus engine? These can be had for relative peanuts and are pretty strong. The Audi lump is great I'm sure but how many of those were ever made and they ain't going to be cheap - I'm assuming here that they are different from the standard A6/A8 4.2's?

[Ormes]

If you want a V6 enginge... how about a BMW 335i TT? Sound nice and assume plenty of scope to turn up the boost?

[14500rpm]

If you want a V6 enginge... how about a BMW 335i TT? Sound nice and assume plenty of scope to turn up the boost?

335 is an inline six.

[Korkey]

Firstly. Thank you all so much for your time and input with what I was trying to do. This forum is a great place to be and many of you are very knowlegable and free with your time and help. Right...............here are my thoughts so far......this may be a bit jumping around and not a,b,c. I use my VX for touring in Europe. I am recently back from a 3000 mile trip in Spain and Portugal. This trip had the boot stuffed to capacity and an original VX boot rack and every little nook in the VX. That is the reality of travelling with a lady companion. I can not loose the boot capacity. The Audi V8 looks on early measuring as though I would loose some of the boot depth.....front to back. This would render it almost useless. To fit the Audi V8 in a transverse attitude I need to find about 75 + mm of space, front to back. Other V8's might fit better. Look at that beautiful Rover V8 instillation.....such a great job there. But I and my friend Ray Webb and Rob at what is now V8 Developments ( formerly Rovertec ) have spent many many years tuning and developing the Rover V8 for serious power output........well the reality is that to do that to a level that gets close to the Audi is in the region of £7 to £8K and it still will not rev. So that engine, for me, is a no. Now that I have learnt more about the VW Audi V6 engines it seems that to get them to 350 Hp + is also very expensive could run up to £10K with forced induction. If an engine swap is on the cards for me then my first choice would be a V8. truth is, the more I look into it the more the validy of Nev's monster creation comes to the fore. And also the comments of Winstar and cnrandall. Nev, I know for sure. Spent simply ages looking at all sorts of options before he embarked upon his quest for ultimate power. To swap out the VX turbo engine for another 2.0Lt is beyond me. That is to say. I can not see the point. Also when we look in depth at the VX turbo it becomes obvious just what a great serious power plant that engine is. Talking about that engine, as I am. Speaking with Nev, he is my point of reference because I admire and respect what he has achieved with that engine. It would seem that to take it to say 340Bhp + then a change of some internal components is required. ( Also referencing Liam here who has taken his to 350Bhp with no internal changes, but since dialled it back to 320Bhp. ) Here in then lays the next issue. My original idea was for say 340/350 Bhp. Now this seems to be the very edge of power with standard internals. So does once chance it and if it goes bang, well, then it goes bang. If we change some of the internals, rods and pistons then we may as well go for 380/400 bhp and then change the cams, as we now have good rods and pistons we can rev harder and quicker and longer. Obviously there are a lot of external works to do......turbo, inlet, exhaust, etc etc. What I found with my stage 2 VX at Guadix race circuit was this. I needed some more revs that where also producing power, not just revving. I needed some more power.......maybe 320Bhp would be enough when coupled with more torque sooner and lasting for longer than my stage 2 has. The Audi V8 engine looked as though it would of done all of that..........but for me it just will not fit in as I need. Oh yes, it will fit, just not how I want it to. So you guys. How would we build a 2.0Lt turbo with standard internals at 320 + Bhp with a bigger torque curve than the stage 2 starting to build torque faster, revving harder up to around 6500Rpm and producing torque beyond 5000rpm ? Any thoughts? As always. Thank you for your time. Korkey.

[Duncan VXR]

TFSI K04 VAG Standalone conversion for the LET / LEH setup will help with the power delivery / control As always it's budget controlled as there are a lot of things that can be done to the LET / LEH to meet your requirments. All adds up mind and your going to need to change turbo application for sure imo DG

[Rosssco]

Rich, maybe you should look at the Z28NET/L engine, which is a single turbo-charged 2.8L V6 engine, that has some compatability with existing gearbox options, and would provide you with ~350bhp and similar torque without internal modifications. They are relatively compactly packaged, and you probably wouldn't have to reduce your boot space to fit one.. This engine also lends itself (IMHO) to production of a 'kit'..

There's a bit about tuning them on Courtenays website:

http://www.courtenay...ng/info_87.html

Sorry if I keep harking on about +4 cylinder engines, its probably just that I don't have the means, but you do, and would be good to see such conversions becoming popular..

Ross

[Nev]

You can just realistically get the OEM engine to 330/340 BHP using the Astra VXR turbo (assuming the rods dont fail), but you'd need to get all the breathing pipework + inlet + TB spot on. You won't really get the torque to kick in lower as the OEM turbo governs that mainly, however there will be more of it (approx 370 ft/lb at peak). The bugbear of this is that you will start running out of puff by approx 6100 RPM (ie power dropping away), this too is limited by the OEM turbo which only pushes out 16 lb of flow per min. Ultimately max revs and bhp is always governed by turbo size, if you stick to the Astra VXR turbo this will run out of puff at circa 6100 RPM or 330 BHP. Thats the bottom line for the OEM setup. For B-roads this is plenty, but you want to track so you face the dilema of deciding if you want more... The problem with wanting more than circa 330 BHP in the Z20LEx is you have to pay for and do the following. 1. Necessity to change rods + bolts (or you face a BIG risk). 2. Turbo size increase. 3. New exhaust manifold. 4. Remap. 5. 3" exhaust advisable. 6. Good charge cooling. 7. Pipework enlargement everywhere, TB enlargement. 8. New inlet manifold. 9. New injectors. 10. Lots of other smaller bits and bobs. 11. Camshafts. Suddenly with that lot you are looking at a big build and quite a lot of money. This is why exceeeding 'stage 4' is such a costly excercise and why so few people do it. In practice it makes little cost difference if you want 360 BHP or 460 BHP, all the same components need swapping Once you are looking for 450+ BHP mods you should start to think about approx £2000 worth of head mods.

[Korkey]

Duncan and Ross. Thank you both for that information. I will go take a look and see if I teach myself anything. Pease, keep going on about anything.........I am open to ideas and to do something different is always good. Hi Nev. I agree with you. It will be standard internal unit up to the figures you have put forward, or then an engine change. As you say............it all adds up. It is not that I am against going beyond those figures, or even spendinmg the money. It is that you have already set the bench mark......and it's bloody high! Regards. Korkey.

[Nev]

Rich, maybe you should look at the Z28NET/L engine, which is a single turbo-charged 2.8L V6 engine, that has some compatability with existing gearbox options, and would provide you with ~350bhp and similar torque without internal modifications. They are relatively compactly packaged, and you probably wouldn't have to reduce your boot space to fit one.. This engine also lends itself (IMHO) to production of a 'kit'..

There's a bit about tuning them on Courtenays website:

http://www.courtenay...ng/info_87.html

Sorry if I keep harking on about +4 cylinder engines, its probably just that I don't have the means, but you do, and would be good to see such conversions becoming popular..

Ross

Unfortunately, that engine seems like a good idea until you see how much torque it makes, 430 ft/lb for just 340 BHP. Ideally those numbers need to be the other way round for a light-weight track car. The problem of turbocharging V6s or V8s is excessive torque and not enough power due to lack of ability to rev . Turbocharged american muscle cars suffer from this a general rule, which is why Americans have a propensity (in general) to supercharge them.

[Rosssco]

Take a quick look at the link below, where the same BASIC engine (i.e. same basic block size / fitment, but different capacity, aspiration etc.) as the 2.8 Turbo Vauxhall engine. It appears to be dimensionally quite a good fit, and using a twin scroll, single turbo (in the case of the Vauxhall engine) over the gearbox, makes things easier from and exhaust packaging perspective... I

http://www.lotustalk...-2x-fun-102052/

[Korkey]

Ross..............crikey! That is one impressive motor. And it is a Vauxhall. I upset a lot of people many years ago by being the first to fit the sbc and LS chevrolet into the TVR Speed Six Tuscan........don't want to there again really. I have yet to read up on Duncans idea, but I will do. Korkey.

[Korkey]

Doh.............Nev!

[Rosssco]

Rich, maybe you should look at the Z28NET/L engine, which is a single turbo-charged 2.8L V6 engine, that has some compatability with existing gearbox options, and would provide you with ~350bhp and similar torque without internal modifications. They are relatively compactly packaged, and you probably wouldn't have to reduce your boot space to fit one.. This engine also lends itself (IMHO) to production of a 'kit'..

There's a bit about tuning them on Courtenays website:

http://www.courtenay...ng/info_87.html

Sorry if I keep harking on about +4 cylinder engines, its probably just that I don't have the means, but you do, and would be good to see such conversions becoming popular..

Ross

Unfortunately, that engine seems like a good idea until you see how much torque it makes, 430 ft/lb for just 340 BHP. Ideally those numbers need to be the other way round for a light-weight track car. The problem of turbocharging V6s or V8s is excessive torque and not enough power due to lack of ability to rev . Turbocharged american muscle cars suffer from this a general rule, which is why Americans have a propensity (in general) to supercharge them.

I agree Nev, and in the link posted, the guys using the more robust F40 gearbox, but we know that doesn't fit our cars without subframe mods.. Is there not a way of limiting peak torque, without limiting bhp? I presume increasing revs is the answer, but may not be reliable on this particular engine, and of course bhp is a product of engine torque..

[Korkey]

Ross....that looks amazing. Are the subframe modifications required for our cars possible does anyone know? Korkey.

Edited by Korkey, 15 June 2012 - 10:08 AM.

[Nev]

You can go round and round in circles with this dilema, I know I did for approx a year. It's such a tough decission. Finding an exsiting 4 pot engine like Duncan has with the Audi engine that naturally fits into the 350 to 400 BHP area is quite sensible, it's just that you then face fitting/installation/loom/ECU/driveshaft issues. Which ever way you try to skin the cat, it will be hard or expensive and will likely be both of those with risk management to consider too.

Edited by Nev, 15 June 2012 - 10:09 AM.

[Nev]

Theoretically for a propper track car I think a medium big NA engine with short stroke and high revs is the way forward. Something like a 4 Litre engine with an under-square bore to stroke ratio would be best. I know the BMW V8 M3 engines fill this 'slot', maybe look at one of those (there must be plenty of crashed ones available second-hand)? You'd also get a semi sequential box with them too, which really helps with fast driving, though they have remote transaxles, so you'd once again have to fit the engine in longitudinally with a hell of a light front end as the transaxle would hang out of the back :/ My brother has a new generation M3 ATM and took me out for a scarey ride. It revs like crazy and is nice and smooth, but a bit feeble for a 1.7 Ton car. In a 900 KG VX though it would be a different story. On this note I think Atom-X was/is developing an engine on this basis for his track car, maybe contact him? Car Eh, they do my head in with all the combinations of confiurations! Whats your genuine spend budget?

Edited by Nev, 15 June 2012 - 10:28 AM.

[Rosssco]

The majority of the OHC V8 engines are just too long to fit in the space available. The Audi V8 is a go'er in this respect because it was designed to be as short as possible, but consequently suffers in width as all the tranditionally arranged components / systems (e.g. water pump, oil pump, alternator, cam drive) are located to the sides of the engine. Groundeffect just got away with his RV8, but he had to relocate the coolant pump and other stuff, and just squeezed it in.. V6's are a better fit, and larger capacity (+3L), more modern units like the VQ35, VR37, Toyota 2GR, VAG R32/36 units produce similar outputs to the older V8 designs, as they are designed to used in cars that also come with transverse 4-cylinder engine variants. I guess the OP has to decide what he wants from the new power plant, and what the ultimate use of the car will be - if its just alot more power / torque output, then a modified 4-cylinder FI engine is easier (maybe not on the wallet) and more efficient. If its to do something different, with a potentialy more exciting sound / feel, and more of a standard engine, then a larger displacment / greater cylinder count engine may be the best approach. For a track car, I'd go for the former, for a road car I'd prefer the latter.

Edited by Rosssco, 15 June 2012 - 10:33 AM.

[siztenboots]

Ross....that looks amazing.
Are the subframe modifications required for our cars possible does anyone know?

Korkey.

this gives you some idea, bear in mind same vauxhall/opel engine bay has to support 2L and 2.8L there will be similar