VX Power?>

[Peter T]

Now i no there are afew of you boys running VX 16 V units with good HP, but i need to know at what hp can i reliably get on carbs? Toying with the idea to building a steel unit, to arround 280+bhp, only trouble is tractability with 50/55 DCOE carbs is not suited to road use.Fuel injection is the way forward i have been told, now i like good old fashioned sidedraughts, but i think that drivability will be compremised. Any thoughts? Looks like i will have to go this route as building a new BD will be financial suicide. What about the new Duratec, good or no go?

 

C7 PWT X-Flow all Steel

 

[Peter T]

PS- this does not mean that X- Flows are dead!

 

C7 PWT X-Flow all Steel

 

[Paul Ranson]

280BHP is extreme. I don't think you have a chance of that on carbs, especially if it has to cold start and idle at less than 3000rpm.

 

235BHP is a practical carb output, but I've never driven one, I don't know how driveable it would be.

 

FWIW I don't see what's wrong with injection. It makes all the right noises... At 280BHP you'll be thinking about running an 8 injector setup.

 

Paul

[Swiss_Tony]

Peter

 

Carbs are much better than that horrible injection 😬 😬 😬 😬 😬

You can get decent power from them!

 

The Duratec looks good for power and reliability. There are a few companies doing stuff for them now SBD etc.The only thing I dont like the idea of is the exhaust on the O/S.

 

James

 

 

P17HPC The K2RUM Eater

K2RUMEATER@hotmail.com

[Swiss_Tony]

I heard a rumour that the K2RUM EATER uses carbs but I could be wrong 😬

 

James

 

 

P17HPC The K2RUM Eater

K2RUMEATER@hotmail.com

[Swiss_Tony]

😳

 

 

 

P17HPC The K2RUM Eater

K2RUMEATER@hotmail.com

 

Edited by - james on 31 Oct 2002 23:59:31

[AMMO]

Carbs are great for the Third World. For those of us fortunate enough to live in the Second World, fuel injection is a viable alternative. Just bought an MBE 967 ECU today, so I'd have to say that.

 

Anyroadup. Carbs tend to rely more on the venturi effect so there is a limit to what choke size you can run. I'm afraid fuel injection, with it's larger throttle bodies and better air gulping abilities will always give better power.

 

Crossflow with carbs. Ai caramba, que disastro!

 

AMMO

[Trevor Phillips]

A true 280bhp on carbs - probably undriveable at low revs. BTCC Production spec cars on TB's reached around 300bhp but had some reliability issues and most ran around 285bhp with all their expensive trick bits. There are two 320bhp engines for sale currently in SA for big money. Also rumour says that Jade Motorsport may be selling a high-spec VX but it won't be cheap if they do part with it.

 

IMHO 275bhp on TB's is about the most you could reliably get. Put an alloy block on c. £3k and you can build a better and equally as light engine as the Duratech for a lot less. I was recently quoted £17k for a Duratech 270bhp engine from a well-respected tuner. Then there was around £3k for the ancillaries and conversion. Fell over laughing - not my sort of budget. Serious money when a VX is a tried and tested route and can be done for £7k less.

 

Racing pics and items for sale here

[EFA]

Trevor,

 

The Swindon BTTC engies were capable of producing "over 330bhp" but regulation imposed a maxRPM ofb 8500rpm, and this is why the power dropped - the later Cavaliers were still producing 310bhp+

 

Paul,

 

You do not need 8 injectors to produce 280bhp, this is an overly simplistic view. You might attain 280bhp more easily (i.e less modifications elsewhere) with 8 injectors as an additional set of injectors will allow the fueling to be more optimal in terms of atomisation at high RPM. Obviously the same performance could be gained by running a 4 injector setup with the injectors positioned more remotely from the combsution chamber, but low end performance would suffer terribly. The second set of injectors purely addresses this low end issue.

 

I am not telling anyone why I run beige injectors on my engine, but there are only four, and the reason is very much connetced with the overcoming the above issue whichb is how I achive 280bhp without loss of bottom end tractability (150cc's extra given.....)

 

280bhp is achievable on carbs, but in order to do so, the choke sizes will be so enormous, throttle response at lower RPM (<5000) will be severly compromised.

 

Building a good engine is not about peak power, but is all about the way in which such power is delivered, the ideal being progressively across the entire rev range.

 

Even DCOE style throttle bodies so not address this problem, taper bodies(irrespective of brand) being the ideal way to adress this issue.

 

If someone marketed taper carbs, the disparity between carburettors and injection would be far less.

 

There is only one snag with injetcion. Up front cost - if you plan using the car on the road, you will see dramatic imporvements in economy, so over time this cost is recoverable.

 

Fat Arn

Visit the K2 RUM website

See the Lotus Seven Club 4 Counties Area Website here

 

 

Edited by - fat arnie on 1 Nov 2002 10:03:24

[Trevor Phillips]

Arnie,

 

I agree. TB's smooth a race engine out and for most circuits high torque can be equally as useful as power at high revs. In the wet torque really helps on the circuit.

 

Racing pics and items for sale here

[cdg]

If you really have to have carbs I suggest you bin the Webers and go to a set of large bore flatslides. They incorporate accelerator pumps, but more importantly have a variable venturi, so airflow throughthe carb is always at it's optimum (after a little practice). In effect you have a variable choke going from just a couple of mms to 48mm+ so when wide open they give the same throttle area as a 48mm body (more actually as there is no butterfly getting in the way).

 

The Americans have been using these for years in performance car applications, but as always we tend to conservatively lag behind and stick to our "traditional" old Webers.

 

Chris.

[Paul Ranson]

You do not need 8 injectors to produce 280bhp, this is an overly simplistic view.

I didn't suggest you did. I suggested you'd be looking at 8.

 

I have a 92 Swindon BTCC spec engine. 4 injectors. This would be road driveable, (in fact I have driven it on the road)

 

for most circuits high torque can be equally as useful as power at high revs.

I think I'll leave that alone.

 

Paul

 

Edited by - Paul Ranson on 1 Nov 2002 15:10:16

[Joost M]

Arnie

 

Quote:

The Swindon BTTC engies were capable of producing "over 330bhp" but regulation imposed a maxRPM ofb 8500rpm, and this is why the power dropped - the later Cavaliers were still producing 310bhp+

 

 

The Swindon BTTC engines never made more then 285hp@8500. Inn Germany (STW) the same engine from Spiess made 335hp@8500. That is why they changed from Swindon to Spiess in the BTCC.

 

Regards,

 

Joost

[rjc]

When I upgraded my engine (VX 16 valve) I talked to SBD QED and Swindon. I can vouch for Eric Pasteur at Swindon 'cos he spent quite some time helping me.

 

There are upgrade kits availalble for VX engines which go up in series, all of them approximately the same in cost terms when you take into account the differences between them (some include more items as standard).

 

Starting from 175 BHP for the standard engine on carbs up to 215 can be realised with just cam. piston porting and timing mods. Above that and you will need conversion to solid lifters, some head work and pistons. Usually at this point the carbs are ditched for fuel injection which allows the most to be made of the mechanical upgrades.

 

These kits are worked out by the experts and if you go different the liklihood is that it don't work as well. There is no reason why a fuel injection rig with K&N filters can't be done. This would be practically indistinguishable from carbs. But most people fit a one piece foam jobbie so as to maximise breathing potential.

 

talk to the experts Eric can be reached on 01793 531321.

[Paul Ranson]

Inn Germany (STW) the same engine from Spiess made 335hp@8500.

And if you believe that....

 

Paul

[Marius]

>Inn Germany (STW) the same engine from Spiess made 335hp@8500. That is why they changed from Swindon to Spiess in the BTCC.

 

A 2 litre real 335hp engine would be an absolute one-way engine, I doubt you could do a whole training session or even get to the end of the pitlane without blowing it.

 

Ssshhh, Joost, keep calm. Have you ever been to Spiess ? They´ve got quite a few Swindon-parcels lying around there.....

 

Marius

 

 

 

[Swiss_Tony]

Paul Ranson and Arnie

 

Please could you give a few more details of your back to back testing with carbs and injection?

I think it would be very helpful to quite a few poeple as well as myself.

 

James

 

 

P17HPC The K2RUM Eater

K2RUMEATER@hotmail.com

[edmandsd]

There appears to be two power claims on this thread that are absolute tosh and one's from a race of sunlounge hoarders....

 

Home of BDR700

[Joost M]

@ Paul Ranson

 

Quote:

And if you believe that....

 

I don't have to! I know it! I discussed this matter with my brother last week. He is a race-engineer for Holzer (Opel Performance Center). They were responable for some STW cars. He engineerd Uwe Alzen, Manuel Reuter and Roland Asch. They are selling the STW stock at the moment. He gets a discout of 80%!!!!!. (Still very expensive. So I was thinking of buying some parts for my engine). They used to use Swindon in 96 and changed to Spiess in 97. In 99, the last year of the STW they had 2 engines. One with a MTB of 100 miles and 335hp and one with MTB 900 miles and 320hp both at 8500. MTB meens in this case it needs a major rework after that milage. The first one was only used to qualify.

In 98 L. Lacroix changed his job. He went from SMS to Triple P (Germany to the UK). 97 was a a problematic year for VX in the UK. The reason was that they were down on power. So they had to drive a low downforce configuration and that is killing with the circuits in the UK.

 

@Marius

 

See above + believe me if they change from Swindon to Spiess in the UK it has a reason. If there is one company who knows how to tune the old VX16 than it is Spiess. They did their 180th!!!!!! victory in the F3 this year with that engine.

If you don't believe me. I will invite you to a DTM-race and you can see the whole development from Spiess at their best (at work). And believe me there is a whole lot of difference between a STW VX16v and the one you are using. For example they use a mapping for the engine that is specific for every corner of the circuit with all possible wether types.

 

@Trevor

 

I think this is one of the engines you mean. It is one from Spiess.

Spiess engine in SA

 

Edited by - Joost M on 2 Nov 2002 19:02:03

[EFA]

I think Joost is a little confused as to what is an Ecotec and what is an XE - Sure it took some time to get XE power levels from the Ecotec. I dont think any of them ever got near 335bhp with the 8500rpm regulation.

 

In 1996 the BTTC cars were not Cavaliers but Vectras, and they of course used the Ecotec.

 

 

James, The carb vs Injection theory is based upon several engines as perceived fron the drivers seat, before and after conversion. Carbs can gives as much power as injection, its just that in doing so the drivability of the engine is destroyed. Caterham had the same issue with the JPE - its DCOE sytle TB's being the main cause of its problems.

 

Fat Arn

Visit the K2 RUM website

See the Lotus Seven Club 4 Counties Area Website here

 

[edmandsd]

It's the 8500 rpm limit that makes it unbelievable Joost. If you said they'd somehow managed to allow it to rev to 11,000rpm it would be more believable (Like the Esslinger 2lt Zetec with 295bhp at over 10,000 rpm). Other thing to consider is that with a switch to these engines from what was already a competitive car, they'd have outrun the opposition by miles and they didn't did they.......unless everyone else suddenly found an extra 50 bhp all of a sudden.

 

A proper Hart 2lt giving max power at 9,750 doesn't show anywhere near this amount of power and it's designed to give power with a big bore/short stroke design and huge valves, induction and exhaust compared to a vx. However efficient you make a vx within the confines of an 8,500 rpm threshold you are never going to achieve this short of peak power output.

 

I was only recently privileged enough to witness an ex works 4 cylinder 2.5lt BMW on Powerstation's rolling road in Cheltenham and that showed 318bhp with an 8,500rpm limit....which is enormous power for this particular rolling road and the engine had been built with an unlimited budget.

 

 

 

 

 

Home of BDR700

[Paul Ranson]

Please could you give a few more details of your back to back testing with carbs and injection?

Please could you explain why you are asking?

 

I think it would be very helpful to quite a few poeple as well as myself.

First, do you understand how a carburettor works? I think there are some good web sites around that might help you.

 

Paul

 

[edmandsd]

James - A well set up pair of 48 Dco'sp will give bloody good power but a proper sequential 4/8 injector set up should outperform them due to the increased flexibility.

 

Only thing I would suggest is that you pick a proper management system and get it set up by someone who knows that system inside out. I put a wasted spark lumenition system on my car with the Cosworth slide and it was dreadful - worse than on 48's - The fuel stand off was a joke. I therefore moved to a fully sequential Motec system which is a lot dearer but it's superb and has enabled me to really get the best out of my BD.

 

Home of BDR700

[DaveK]

Thanks Dave

 

I was just about to point out the same thing re Hart race engines.

 

A lot of figures were bandied about in the touring car era which were no more than mines bigger than yours statements for advertising purposes.

 

Any thing over a genuine 275 bhp will cost a in excess of 10k for parts alone with out the necessary expertise to build it.

 

I think the best thing to do is to beg to differ and let results do the talking.

 

FWIW If you take the curborough speed trap figures into consideration and the claimed Bhp figures for the cars then this does not make any more sense than argueing over which company boasts the highest power figures

 

Dave

[Swiss_Tony]

Paul

 

I do know how a carb works!

I was curious as to the difference between a top spec carb and injection engine.

I have not tried injection on mine and I dont want to spend over £2000 to find no real power advantage. I am very happy with the driveability of my engine so this is not an issue for me.

 

James

 

 

P17HPC The K2RUM Eater

K2RUMEATER@hotmail.com