Titan Roller Barrels vs Jenvy DTH

[Kal-El]

I'm at just about to place an order for a set of throttle bodies for my car, and I can either purchase the Titan RB's or a set of Jenvey DTH bodies. Both are about the same cost. I'm leaning towards the Titan's as they are fitted by Caterham but wanted to get some feedback from users of both. The general consensus is that the Jenvey's are better at part throttle, but I'd like your opinions?

If anyone has the roller barrels, and is in the Kings Langley / Hemel area and is willing to take me out for a spin I'd be very grateful.

 

Thanks

 

P

[BBL]

I am a bit far away from the Kings Langley/Hemel area, but I do have the roller barrel throttle body on my car, and (after mapping) partial throttle is as smooth as any other car I have driven. It had been initially "kangaroo-ing" at part-throttle, but mapping sorted that. I would think that you would be pleased with the performance of either Titan roller or Jenvey butterfly, but know going in that any changes of this type will benefit greatly from mapping after the change.

[7 wonders of the world]

You just need to look how many race teams use butterfly's over barrels or slides, absolute performance *may* be slightly higher on rollers however transition and driveability is better due to the gas speed and induced turbulence in the air stream on butterflys.

 

In order to get the best out of either you will more than likely need to cut the bonnet even on an SV they can be marginal.

 

There's more info on both Jenvey and Emeralds sites

[Ads7]

RB's are designed for flat out driving like racing with cars that have a high tick over so don't really need to worry about partial throttle. They are very Gucci hence in part people like them. Butterfly's are more forgiving as on partial throttle the air is taking a smoother route into the cylinder unlike the RBTB's.

 

Personally I went for the Jenvey DTHTB's as they were simple and easier to use for road driving.

 

Adam

 

Orange caged 7 at the squirrel pub on Saturday. Great to me you

 

 

 

Edited by - Ads7 on 4 Sep 2014 22:19:21

[BBL]

Just to qualify my comments, my engine came with RBs from new, and I have never driven a Seven with an engine that did not have RBs. Just saying, partial throttle is not that much of an issue in my experience.

[oilyhands]

In addition to the comments I made on PH and those made here, the RTBs have very large runners which are much larger then the inlet ports on a stock head, this will cause a large step in the inlet tract at the manifold face which is very bad for airflow. If the head is on the engine then sorting this out is anything but straightforward. The Jenveys are a much better fit and will follow the shape of the inlet port almost exactly.

 

Oily

[Pete - W.Sussex]

Just to confuse, I had Titan RBs fitted on my R400 Duratec with a standard Caterham remap and they are great. No problem on part throttle and the car picks up better with more breath at the top end - the cool air it now gets from the hole in the bonnet may be helping too.

[Kal-El]

Thanks for the responses everyone.

 

I don't know anything about the std Caterham cars on RB's, but I've been talking to a friend of mine who has suggested I run the ECU in a hybrid alpha N setup. What this mean (I think) is that the ECU will use MAP at part throttle openings and then auto switch to TPS after a certain threshold. Do your RB's have holes tapped into them with tubes for the MAP signal, or are they running alpha N?

 

P

[oilyhands]

Why you want to do that? Alpha-N is a better way when you have more cam duration and TBs as a stable map signal is very hard to find.

 

Oily

[Kal-El]

The ECU is using Alpha N, what the hybrid mode does is uses MAP for pressures of 0 - 90 kpa, then above this threshold it switches to alpha N. The reason for this is lets say you are driving in traffic and move the throttle position from 4.7 to 6.2 percent for example. On the 16x16 map there's not enough resolution for the ecu to compensate the fueling requirement. Using MAP however the kpa may go from 45 to 90 which is almost doubling the requirement for fuel and the ECU can compensate for this. Above 90 kpa it then automatically switches to alpha N. We're only talking small differences, but I am hoping that this will make driving in traffic a little easier. Has anyone had any experience with this setup?

[oilyhands]

There is plenty of resolution with the right ECU, the Emerald for example has relocatable speed and load sites with all of the granularity you need. If you wished you could pack in the load sites twice or three times as close as they are as a default and the speed sites at 100RPM intervals for the first 6 or seven sites above idle.

 

MAP/Alpha was the cause of the terrible running of the early VHPD engines, many of the ECUs were replaced with Emeralds or similar running an Alpha-N strategy with fantastic improvements in drivability as a result.

 

Oily

 

Edited by - oilyhands on 5 Sep 2014 14:27:52

[Kal-El]

Hi Oily,

 

You'll have to excuse my ignorance but I'm hoping you can explain a few things for me as I am still learning a lot here.

 

With regards to the VHPD, how did having hybrid alpha cause poor running over just an alpha setup, it doesn't make sense? I was under the impression it was down to cam timing and simply poor mapping, rather than the technology.

 

Also, the Emerald has 32 speed sites adjustable to a resolution to 1 rpm which is great, but how does that solve the fuelling issue of load vs small throttle angles at low revs?

[oilyhands]

The engine Is mapped at each of the load speed/sites, this ensures the fuelling and timing is spot on for any given load and given engine speed, other than that I don't understand your question. Interpolation between the sites provides transients. And if the load/speed sites are close together I just can't see the problem. The fuelling and timing requirements will always be the same for any speed/load condition(ambient adjustments not withstanding).

 

Oily

 

Edited by - oilyhands on 5 Sep 2014 17:58:26

[Kal-El]

Oilyhands, so interpolation is filling in the gaps? If we are half way between two throttle sites will the interpolation make the fuel half way between?

[oilyhands]

That will depend on the previous load site as the fuel slope has progressed,  but it won't be far from halfway.

 

Oily

[Kal-El]

Ok I think I understand, so if I had 10 fuel at idle, 0% throttle, and that had a perfect afr, and I had 20 fuel at 2% throttle with perfect afr (let's say on the 1000rpm column) the ecu would interpolate 1% throttle to be a fuel value of 15? Assuming my throttle spacing was 0,2,4... At the bottom?

[oilyhands]

It's never that simple as the throttle and speed change at the same time, the engines progression through the is generally on a diagonal trajectory so there are usually a few more load/speed sites involved in the interpolation.

 

Oily

[Kal-El]

I was asking about the way the algorithms inside the ecu firmware functions rather than the resultant dynamic of actually running an engine. Assume for this question a braked rolling road holding steady state rpm so we can change throttle angle without rpm changing. I am really interested to fully understand how this works.

[oilyhands]

Well pardon me, I thought you were interested in how well the engine would run when actually using it rather than the contrived and artificial situation when mapping. If you peg the RPM then naturally the interpolation works in just one dimension. However you are unlikely to be in that situation at any time when actually using the engine. I think you could probably work that out for yourself.

 

Dave

[Red SLR]

Previosuly had both.  Cant say as I noticed a huge difference myself.  Perhaps the RBs felt and sounded a bit smoother - but that could have been very much to do with the map.

[Kal-El]

My apologies if you thought my response to be rude, it certainly wasn't my intention. I was just trying to make my question clear. I was simply asking how the algorithm within the ECU functions, which was the reason behind my "contrived" scenario. Your response however does answer my question, but also highlights the flaw in alpha-n mapping at low Rev and throttle openings due to the large change in air flow against a tiny change in the throttle pot. How we can map around this using throttle enrichment transients and closely packed load sites is an interesting one. This is why I questioned using a 'hybrid' strategy which uses the MAP signal below a set threshold and the TPS above it. Since the map signal responds with high resolution at low throttle openings it's advantageous to use it and since map signal has low resolution above 90kpa it is advantageous to then switch to TPS. In your previous post you mentioned that this caused problems on the VHPD engine, and I am keen to understand why that's all. You mentioned about how the engine actually runs on alpha-n, and my own limited experience has seen that on a car with throttle bodies, and cams is that there is a lean off at tip in which means the engine stalls. This means that I have to then drive around the problem. I suspect many people on the forum may have a similar issue, and I thought a sensible debate about alternative solutions would be healthy.

[Golf Juliet Tango]

D you need to read this?

http://www.haynes.co.uk/Press/HaynesJackets/RGBhr_4199.jpg

[oilyhands]

There is an article on my website that has been paraphrased on Emeralds website about engine management, it doesn't go into detail about the actual algorithms or heuristics used to implement the interpolation but Knuths fundamental algorithms would probably allow you to work out what strategy is used.

 

Accelerator clamp is used to cover lean fuelling over transients, you will experience this on any system be it MAP based or Alpha N.

 

The EMS article is accessible from my home website www.dvandrews.co.uk.

 

Oily

[21jigsaw]

 Interesting, I am just going from throttle body's  to rollers due to low speed drivability issue. Lack of control from idle to 2500 / 3000 - its either on or off. Rollers on my other car are far more progressive and controllable. Both engines are the same spec - 1800 VVC running the  mems ignition ECU. The original tune was with the rollers. 

Looking at the throttle opening it can be seen that the area around the butterfly's is greater and less progressive than the orifice on the rollers. 

I think which ever way you go, the end result will depend on the vehicle/engine spec. and set up / tune. It will be  very difficult to quantify whether you made the right decision.

[oilyhands]

If the map was made with the rollers then the calibration will reflect the rate of change in airflow per degree with the rollers, rather than the TBS and vice versa. I have had around 250 engines mapped with regular TBs and Alpha-n load mapping and haven't experienced any problems.

 

Oily