Differences in VX power with similar set up.

[kenny.]

I,m not a BHP waffler but thought I'd ask for comments on this point anyway out of interest.

The first engine mods I did on my HPC were to fit QED 42H cams, DTA 3D box with throttle pot(car on standard 45 webbers) steel oil pump gear, rod bolts etc. for safety....car gave 180 bhp at wheels on reputable and very well known rolling road.....I thought maybe this was a touch high, but what the hell as the car was certainly livlier.

 

Anyway I've just de-mothballed my Banks Europa and done virtually the same mods to it with a couple of differences.....QED42H cams again but 48mm Jenvey/Luminition throttle bodies/MBE box..the engines are both XE motors but the Europa was the later distributerless one with the drive peg bolted to the exhaust cam(not used on this car).

 

Point is after a couple of hours of driving and setting up with Lambda probe in exhaust by the guys...the car showed 190 and just a tad over on rollers and felt very sharp indeed on road.

 

As I said, figures mean nothing to me in reality but what is the feeling here regarding the difference in power output from two very similar setups.......both engines by the way are less than 5000 miles old and very fresh......10 bhp seems a lot of difference and I can't see where that comes from.....thanks.

 

Kenny HPC

 

PS Probably not, but does anyone know of gear kits/sequential boxes for VX F20 box as first gear in Europa is now redundant..much the same as first gear in HPC was with standard ratios......cheers

 

 

 

[Alex Wong1697456877]

TB's vs Webers and a different drivetrain could easily account for 10 BHP.

[Roger King]

I'll second Alex on this, plus are both exhausts identical?

 

It's not uncommon to find 4bhp difference between engines that are identical anyway. If anyone knows why, I'd like to know.

[EFA]

Kenny,

 

FI vs carbs aside there are many things which could make a difference....

 

Choke sizes, Trumpet lengths, Gearing, Tyre compound etc. all will make a difference on the rollers. But then I am a real sceptic of accuracy of the rolling road anyway.

 

Once you add FI the issue of fuel pressure, better mapping etc all make a big difference.

 

On DCOE bodies the differences would be smaller compared to taper bodies or slide/roller barrel types, but I still do nto think 10bhp is a huge differnence at all. I would not be surprised to see much more.

 

Think about Dave Edmunds car - achieved a 15% (correct me if I am wrong) increase going to FI from carbs. That would be 25 -30 bhp on a std VX!

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[kenny.]

Thanks for replies with some cracking points made. I just assumed that a well mapped set-up with either carbs/FI would give very similar figures. Obviously the point on exhausts is a good point...on the 7 I have the 4 into 1 2" primary side exit and on the Europa it's a 1 5/8" primary with a very short run (engine is transverse). Gearbox in 7 is Quaiffe pro box with 2.01 first Europa is bog standard F20. I know very little about mapping and don't profess to, but the MBE system on the Lotus seemed a lot more complex than the DTA I put on 7....there seemed to be a lot more mapping points to sort where the DTA seemed quite straight forward. I agree with comments about power outputs on rolling roads....I just use the figures as comparisons. The only other point I'd make and don't know if it's relevent is that the Europa tends to put all its power down through the wheels(no LSD) where the 7 must lose some on rollers (Suretrack fitted) because of spin..might be wrong there though.

 

Anyway it's just reaffirmed my belief what a cracker the VX is to get decent power for not a divorce causing amount of money....I'm going to get the 2 cars on the track together shortly with timing gear...a couple of the lads think Europa will get the better of the 7..but even though as I've said I'm not 100% happy with 7's characteristics I still think it will come out on top (Just need a decent driver to do this for me!!!!)...thanks again for input.

 

Kenny HPC

 

 

[I reply to every thread]

"Engine is transverse" ? Huh. When was the last time you looked under your Europa Lid Kenny?

 

Edited by - AVES on 24 Nov 2001 13:36:25

[kenny.]

When I cammed it yesterday Matthew!!!!......It was the first of the transverse cars chassis no19 and has what I believe to be a better weight distribution than the inline car I had first with NG3 box. I will email a pic of engine bay which you may find of interest as I know a pal of yours has one. Richard also looks after barristers race car.is this one of your mates Matthew?.he has chambers in Liverpool.

 

Kenny HPC

 

 

[I reply to every thread]

Sorry Kenny - I take it back. I'm struggling to imagine it so I'd like to see a pic.

The guy I know was about 10th to have the conversion done at all.

 

He's a surveyor so no-one you know. I'm sure Richard will remember him though!

[Ben Willis]

I have had a similar experience. My car was bought with what was reported as a bog standard Caterham Weber 45 Vx - 175bhp. At one of the 7 list Dave Walker days it made 184 (as reported in CCC). This is about the same as a certain carbon bodied pretender made on the same day (even after it had its throttle linkage fixed) and mine made quite a bit more torque too. The other car had cams (mild-ish QED ones Q...) and 48s I think.

 

The explanation I got was that the heads are hand finshed in the factory and I probably got a Monday morning rather than Friday afternoon one. Plausible?

 

I now want more power and was thinking of dropping in QED's starter cams to get me going nice and cheaply, but I hear lots of people with this set up that make less than mine already. Is mine already modded? Will swapping cams downgrade me. Should I just leave it alone? Does any of this make sense?

 

Ben

[gee_fin]

Pah, carbon-bodied pretender tongue.gif

 

I've was running either Q32Hs or Q38Hs at that event, can't remember off the top of my head I'm afraid. I swapped the head to test another one at the second Se7ens list meeting and it saw 7bhp and 8ft/lbs more on what was meant to be a standard head. (first head 181bhp, second one 188bhp) - just twin 48s and mildish cams. *shrugs* I guess their castings were not that unifrom.

 

Time to get polishing the other head I think....

 

________________________________________________________

graeme finlayson / tyre warmer / fluke motorsport

graeme.finlayson@vicorp.com / www.fluke-motorsport.co.uk

 

Carbon-fibre sale bonanza!

[EFA]

Graham,

 

Cam timing tolerences could cause this.

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[stevefoster]

Ben,

My standard HPC on 45's made 184 at a rolling road and 184 with the AP-22 test device on the road.

 

When I 3d mapped, it needed a Formula Vauxhall engine map to prevent pinking which suggests it has a slightly higher compression ratio I think.

 

Mine is a 1997 car with engine supplied new by Caterham.

[Ben Willis]

Steve,

 

Wow, so do Caterham make habit of supplying better than spec engines? Sounds good to me. The Emerald day had an R500 making more than it should too. Mind you I hear that the JPE was under 250bhp usually?

 

Luck of the draw I guess - and we both got lucky! It sounds like you had the same starting point as I have - would you recommend whatever you did as a route to making it go faster?

 

Ben

[stevefoster]

Ben,

I am sticking at the power I have for the moment.

I intend to spend some money on myself instead.....

[EFA]

Steve,

 

Sorry to dampen the enthusiasm, but nmy Caterham 235 only made 196 with a ported head and hi lift cams. Think this would have accounted for more than a 12bhp gain.....

 

Its generally accepted that a well built VX on weber 45's will give 175bhp, and on 48's it'll give 180bhp.

 

Asa reference the R500 press car was delivered with 230bhp, and all customer cars have been in the low 225's to preserve reliability. This is not hearsay, but is from a very informed source within Caterham.

 

JPE lost loads of power because of inlet manifold and exhaust design.

 

Sort these out and 250bhp is obtainable. This was achieved at max rpm. Reliability with the JPE engine running 8200rpm on std rods is somewhat questionable. Several all steel JPE's were also built.

 

 

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

 

Edited by - Fat Arnie on 26 Nov 2001 23:12:13

[Ben Willis]

Arnie,

 

Very interesting. I had thought that 175 was it for a Vx on 45s too, so I was very surprised to see 184. One of two things are happening here:

DW's road reads high (by quite a lot). This conflicts with many many other accounts of it being within 1 or 2 bhp of reputable dynos. My understanding is that he has done lots of work calibrating it in this way and it is now pretty much spot on.

or

my engine isn't standard sad.gif

 

That fact that Jason Krebs' R500 made 243 on the day also points to the rollers over reading (by nearly 20bhp) or the quoted source being rather pessimistic.

 

Hmm.... Nope I must stop pretending to understand this engine tuning stuff - it clearly defies simple logic. I'll stick to driving, talking of which, I need some thicker gloves.

Ben

[edmandsd]

I wrote to CCC on this very point stating that I believed the 243bhp flywheel figure to be optimistic based upon the graph showing about 185/190 at the wheels.

 

Arnie - My 2lt BDX showed 229 at the wheels on 48DCOE's and 258 at the wheels on 44mm efi Motec slide injection - 12 1/2% increase Only other change was to increase primary size from 2 to 2 1/8th inches and reduce primary pipe length to give same volume. I think the increased power was mainly down to the Motec/slide although I think the increase in primary size assisted the top end power characteristics.