Jenvey's or RB's.

[Billy.Whizz]

What's the best, the reason I ask is that a very well known tuner known to the club has said RB's  are only any good if you upgrade the cams and other stuff otherwise you'll get no increase in power so for £4500.00 for RBTB's from CC it's a lot of money for very little gain. This upgrade would be for my 420R. This person said that the Jenvey's are a much better choice, and also a fair bit cheaper.

[wiltsathome]

I'd agree with the info that you have been given for sure

[ScottR400D]

The Jenveys have a very good reputation and I believe there are pros and concerns for the options. 

I opted for a set of Titan RBs with carbon trumpets installed and mapped by Luke Stevens and Steve Greenald. The upgrade included a better TPS, and injectors etc, everything needed and was less than buying the kit from CC  

My R400 is identical to a 420 and I had a power increase from 210 to 220bhp. (Which is what CC claim) More importantly the torque went from 150 lb ft to 175. It made a huge difference to the sound too. 

The car runs very smoothly and I remember noticing a significant difference in performance when it was done. I'm used to it now but it's still pretty impressive; pulls from very low revs, hits the limiter easily if you want to and sounds great. They've also stayed in tune very impressively. 

I have no experience of Jenveys but they have a good rep, I'm sure someone will give you a review of them. 

 

[ScottR400D]

To add; the 420 already has 'upgraded cams and other stuff' compared with a standard 2.0 Duratec or a 360. 

[ChrisC]

Oh just one point the R400 has a better engine spec compared to the 420, they ditched the ARP rod bolts on the 420 :-(

[ScottR400D]

Really, Chris? I didn't know that. 

Presumably the cams, flywheel etc are the same? 

[ChrisC]

Yes as far as I know, the plenum has undergone a few versions, but since we are taking about throttle bodies here it doesn't seem relevant.  I would imagine they where removed from spec because the % of warranty failure didn't justify the cost.  
Kit builders get the full list of all parts, either fitted or to be fitted, it covers things like the sump and the cams, but no ARP rod bolts, that's how I found out. 

[ScottR400D]

Interesting. When I got my kit at the end of 2014, as far as the engine was concerned I was given a copy of the invoice from the builder to Caterham for a batch of engines, I don't recall  any other details.

So, anyone got any experience to recall of Jenveys?

[Nigel Blandin]

I have had both RBs and Jenvey on my Cosworth BD car.

I loved the Titans, but they were rather heavy and caused cracking on the manifold. They do wear rather a lot and I need to refurbish the linkages and such after a few years.

When the motor was redone we fitted Jenveys. They seem somewhat ...flimsy next to the Titans, but have not given any problems. The two Steves' set up both configurations and didn't express a preference really.

I would say the RBs are better flat out, the Jenveys are more progressive. I know that's a mapping thing, but it seems to poin5 to what is possible. 
I do know one thing though...The RBs sound better!

  I think really, that unless you are racing, the Jenveys are probably a more useable day to day.

Oh, and with my cams, it was a bu**er getting the RBs to close at the end of a long straight! BD motors suck hard and you need a good pair of springs to shut them down. 

[Billy.Whizz]

I was hoping for a bit more information on this from members and their experiences, it's not the cost I'm bothered about, I just want to fit what's best for my car (420R), I will be doing some track days but mostly road use. Thanks.

[Geoff Brown]

From memory the RBTB upgrade does include green injectors & a different TPS with loom, sausage filter, bonnet cut out, ECU programme & labour. If that is all in the quoted £4500 then you could say 'value for money' ?  

A lot of ££££ for 10BHP but the difference is night & day.  Better behaviour on start, good tickover when warm, sharp but 'progressive' throttle response & the noise !! Better with cat bypass. In fact by pass essential as the pops & bangs create flames which will destroy the cat in nothing flat.

Beware loss of creditable MPG when nailing it........

Back in the mists of time (2012) I talked CC around to fitting the package before I received the kit. Was not easy but saved me £230 against a retro fit. The upgrade was much cheaper then obviously.

[Benton]

No experience of Jenveys but had Caterham 420R RBTB done.

Positives:- sound, better mapping/pickup/cold starts, more mid range torque (through seat of pants measurement), pops and bangs!

Negatives:-  slightly heavier throttle action (soon got used to it), needed to buy a decat pipe to avoid destroying  catalytic converter, cost!

Would probably do it again if I had a 420

[ScottR400D]

#10 What exactly do you want to know? 

[7Up]

off topic, but I see nose cone paint seems to suffer in the same areas where the bonnet fits. Any solutions out there?

[ScottR400D]

I've not found one though I haven't tried too hard. 

[Billy.Whizz]

#13. Scott, I'm asking for info regarding members experiences with both systems and the for's and against's before I decide which one to go for myself. Thanks.

[Nigel B]

I had a set of RBTBs fitted to my 420R 12 months ago by Luke Stevens, along with a custom remap by Steve Greenald.

They’re Cosworth roller barrels, as opposed to the Caterham ones, but I believe they have damn near identical characteristics to the Titan/Caterham version.

My last Caterham had twin webers & although I prefer the 420R in most respects, I found I really was missing the induction roar & the general character that comes with carbs.

I think I’m echoing a lot of posters on this thread when I say that the roller barrels have certainly improved matters in that respect! 

The car has a deeper burble at idle & a ferocious howl at high revs. To my ear, it also sounds warmer & sweeter throughout the rev range. I found, with the standard set up, there was a point at around 4000rpm where I was getting what I’d describe as a slightly metallic, harsh sounding, resonant note from the exhaust. That has completely gone since I had the RBTBs fitted. It does have more of a tendency to pop & bang when you lift off, although dipping the clutch immediately stops that, if you need to be discreet. 

I was expecting a few down sides to the conversion. Perhaps worse fuel consumption & more noise whilst cruising on the motorway, but it doesn’t seem to be noticeably worse in either respect.

Previously, from cold, the engine would turn over on the starter motor for quite a while before firing & it had a tendency to cut out for the first five minutes or so, before it warmed up. It now starts almost instantly & idles very smoothly from cold, with no tendency to cut out. I believe the cold running problems can be cured while retaining the standard intake set up, but getting rid of those tendencies was a nice bonus.

It’s often said that roller barrels are better for track use, as they’re at their best at full throttle, but for more precise part throttle response, butterfly throttles are better. I’ve actually found the roller barrels are fine, whilst burbling around town on light throttle openings. It was probably the main thing that worried me before I had them fitted, but if anything, it’s better than the standard set up in that regard.

I have heard that roller barrels are more prone to wear & that it’s important to ensure your air filter is in good condition with roller barrels because if small pieces of grit get trapped in the barrels it can cause problems. I haven’t had any problems in that regard so far, but perhaps it’s something to bear in mind. 

One advantage to Jenveys, of course, is they’re quite a bit cheaper. I suspect parts availability might be better with Jenveys too, as they’re a popular choice. I did seriously consider them, but I found myself drawn to the roller barrels, in part because of their historical association with Caterhams, the R500 K, etc. 

I don’t regret my decision, I’ve been really pleased with them. They’re the icing on the cake, for me.

Gratuitous photo!

[mph]

#3 Did you keep the stock Caterham engine management (MBE?) with your upgrade Scott?

[Billy.Whizz]

Thanks to all for your input, I'm starting to lean towards the RB's, I'll probably go for factory fitted one's as the car is only a year old so still under warranty.

[ScottR400D]

#16 we'll Nigel and I have given our view of the RBTBs, but there isn't much from the user point of view on the Jenveys to be fair. 

[ScottR400D]

#18 I kept the same MBE but it was fully remapped by Steve G. 

[Billy.Whizz]

#20, Scott that's why I'm now considering RBTB's  as most seem to favour them (including a few in my area club), and no one has said anything great about Jenvey's.

[david nelson]

I think I the real world there is not too much difference. Both do the job in a slightly different way. As will all things Caterham it often comes down to you. if the seven is only a yr old and your thinking warranty the CC kit is for you.

resale ask which would you buy? Some will not mind others will not.

why has there been no comments on Jenvey's well likely due to the fact we all follow the majority as its a safe option. 

You know you want the RB is now which ones and does a name mean something?

good luck  

[SLR No.77]

I've had both Jenveys and Rollerbarrels on my K-Series. The Jenveys are easier to set up at small throttle openings for smooth running (and the throttle is lighter at those openings), the rollerbarrels can be set to be as smooth but it takes much more time and effort.  Mid throttle and wide open there's no real difference and the running/performance then becomes influenced by too many other variables, intake length etc. rather than the throttle bodies.  Noise-wise I think there's more influence from the trumpets fitted than the type of throttle body, carbon trumpets sound amazingly! 

The main deciding factor for me was that when I had the car valued (due to impending divorce) Caterham really knocked the value due to non-factory-specification modifications, in their words "it's been too messed with" and was a car they wouldn't take in for sale. Subsequently I have steadily returned the car to factory spec or modifications that would be factory sanctioned. Boring I know, but it can have a big effect on value which is relevant if you don't have money to burn.

Stu.

[Billy.Whizz]

#23/#24. Thanks David and Stu for the comments and good advice.

Bill.