Trumpet base and trumpet length... why are they not similar?

[TVR Beaver]

v8 racing said:

Smaller the plenum the better for me!

Rob.. why?.. does it result in a more direct feed?.. how would it benefit??

This one looks the works.. anyone know what happened to it?.. may be setting the two up would be a problem?..

Edited by TVR Beaver on Tuesday 15th March 21:15

[eliot]

domV8 said:

eliot said:

Yes I guess so, but it would need to be 2" thick. Not sure the bonnet would close?
Seems more trouble than its worth considering trumpets do the job better.

The thicker the machined plastic insert, the more you are reducing the plenum volume.

So surely you would also have to compensate for the reduced plenum volume by adding a plenum spacer in between plenum top/bottom to regain the lost internal volume - thereby increasing the height of the assembly even further..?

Dom

I think (assumed) he was refering to inserting a spacer between the trumpet base and manifold to regain the length.

[Alexdaredevilz]

eliot said:

I think (assumed) he was refering to inserting a spacer between the trumpet base and manifold to regain the length.

Yup I was,

IMO if you blend you could get up to 50mm? and space to get the length the trumpets would of been, would be the best way to go


Can you any issues with doing it that way apart from bonnet clearance?

[Pasco]

TVR Beaver said:

Rob.. why?.. does it result in a more direct feed?.. how would it benefit??

This one looks the works.. anyone know what happened to it?.. may be setting the two up would be a problem?..

Edited by TVR Beaver on Tuesday 15th March 21:15

Ahh the Millennium Falcon Created by The Jedi Master Cliff and fitted to the Dark Lord Blades car and returning numbers good young Jedi

[TVR Beaver]

Paul... Only 'Blades' I can find is Kevin Finney... Is this the guy?

Looks a piece of work anyway.. what did it do?.... any info on it... as I would love to make one

[domV8]

Alexdaredevilz said:

eliot said:

I think (assumed) he was refering to inserting a spacer between the trumpet base and manifold to regain the length.

Yup I was

Yes - no mis-understanding there...

I was referring to the fact that if you need to keep the plenum volume - you would find the assembly got even taller, as you may not only need the manifold spacer, but also a plenum spacer if using a plastic insert...

Dom

[Pasco]

TVR Beaver said:

Paul... Only 'Blades' I can find is Kevin Finney... Is this the guy?

Looks a piece of work anyway.. what did it do?.... any info on it... as I would love to make one

Ok Seriously now

The twin plenum was made by Clivef Clive Ford must be four years ago and is on DNB's, Dave Blades motor now.

Im sure Clive or Dave will be happy to point you in the right direction.

HTH

[TVR Beaver]

DNB.. so that's what it stands for

As in Harry Potter fame

This also may go someway to answer a question I asked here about the LCD in the dash http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Mmmm.. may be worth a word.... I do indeed like to look...

Edited by TVR Beaver on Wednesday 16th March 15:13

[domV8]

TVR Beaver said:

DNB.. so that's what it stands for

...and there was I thinking it was Drum 'N' Bass

[Pasco]

I think you will find its David Norman Blade



Or is it Nigel

[clive f]

it is dave`s design, I made it for him a while ago now, it all derived from a few cornflakes boxes and masking tape.

daves car gives very good numbers and is very smooth to drive with amazing pick up, but it is a very advanced griff, and in the process of being developed even further.

I`m sure dave will pop up here shortly with some facts and info.


I`m none the wiser for what the N stands for either?

[dbv8]

Nitrous?

[v8 racing]

TVR Beaver said:

Rob.. why?.. does it result in a more direct feed?.. how would it benefit??

This one looks the works.. anyone know what happened to it?.. may be setting the two up would be a problem?..

Edited by TVR Beaver on Tuesday 15th March 21:15

Hi John, the downside to large plenum chambers is the lack of throttle response, obviously the bigger the volume between the valve and intake butterfly will reduce throttle response, an engine doesn't need a chamber to breathe it hust needs an adequate air entry, the dnb/clive intake system is a good system and i talked to tim at act about doing something similar about 15 years ago, but it wasn't really marketable due to costs and having to run after market ecu's etc,

[Wotland]

TVR Beaver said:

Rob.. why?.. does it result in a more direct feed?.. how would it benefit??

This one looks the works.. anyone know what happened to it?.. may be setting the two up would be a problem?..

Edited by TVR Beaver on Tuesday 15th March 21:15

Design is pretty similar than Thor Manifold excepted Bosch injection uses single throttle which joins both inlet sides.

[TVR Beaver]

v8 racing said:

Hi John, the downside to large plenum chambers is the lack of throttle response, obviously the bigger the volume between the valve and intake butterfly will reduce throttle response, an engine doesn't need a chamber to breathe it just needs an adequate air entry, the dnb/clive intake system is a good system and i talked to tim at act about doing something similar about 15 years ago, but it wasn't really marketable due to costs and having to run after market ecu's etc,

I suppose more air in the existing plenum system helps with things like reverse flow on overlap so helps to smooth out the intake a bit... So this is why people add spacers and say it helps with shunting and the like... Reduce the volume you'll get better responce but the shudders and shakes that come with it?

But as you say with the more dirrect feed of the set up in the pic... it's a win / win..
Does look interesting for sure.. More along the Cerby style

[dnb]

I have to say that throttle response isn't a problem with the "millenium falcon" inlet. Rather the opposite problem - it's a bit too keen, so I rely heavily on the eccentric cams on the throttle butterflies to keep the throttle response smooth.

I did the original design after the 2007 Growl when I saw a 12+ PSI drop in plenum air pressure at high RPM. This was making it like operating the car half way up a mountain in the Himalayas. The new scheme sees a drop of less than 2 PSI.

I also didn't like the idea of the TVR straight trumpets - my other performance car didn't seem to need trumpets to perform well, instead it had long runner manifolds and a relatively large plenum chamber (and a large turbo, but that's beside the point).

As Clive says, I talked to him and made some models out of cerial boxes and Guiness cans and we came up with something that fits in the car.

First time on the rollers it gave a 60bhp increase, and transformed the way the car drove at low RPM. Nic (the wife) didn't like driving the car with the wild cam until this inlet was fitted.

As Wotland points out, it is a similar idea to the Thor manifold (I have one of these on my other car) but somewhat optimised for fitting in a Griff - leading to something much more Cerbera like.

The inlets are set up such that there is 180 crank degrees between firing events for each plenum, so charge robbing is significantly reduced. The larger than standard plenums do seem to smooth out flow issues too. And there is no loss of torque - the before and after performance curves for torque show at least small gains everywhere.

The down side is the expense - it was not a cheap thing to make! Both Clive and I spent a lot of hours making it work. For instance, I had 11 attempts at making a throttle cable that didn't work like something from a Lotus Esprit v8 (those that have driven one will know what I mean)

Balancing the throttles isn't too bad - just like balancing carbs. The balance pipe at the back helps, but is not a complete solution.

It works OK if you have an aftermarket ECU, but has little chance of working with a Lucas system.

Power wise it's around 320bhp 350ftlbs on 95 RON fuel with an 88 degree thermostat so that it passes the BET emissions test without cats.

This year, I aim to fit cats (boring and normal, I know, but it's preparation for potential MOT rule tighening) and run with a more optimal thermostat - 78 degrees or so - for extracting power to see what happens.
I might even make a 97 RON fuel map - I know the car is detonation limited above 5000 RPM at full throttle - maybe more octane will let me achieve MBT.

N isn't for nitrous. That would be against the wife's car modding rules, and would land me in a heap of trouble.

Hope I answered everyone's questions.

[TVR Beaver]

Sure have!.. Thanks for that.. very interesting indeed... and I can imagine the time taken to get it set up etc... the SS fabrication would not be too much of an issue for me, but the ECU and that side of it would all be very new.
But I'd love to give something like this a go... There must be better ways to feed these units than the original Plenum and it's associated problems and this looks like a good one..... and as it's fabricated, relativley cheap in comparison with casings / machining etc....;)
Will continue to look around this season.. and may be have a go next winter.... I like these projects rather than doing up wishbones / painting outriggers etc

[TVR Beaver]

eliot said:

Alexdaredevilz said:

But with blending you could get say 50mm hole?

But with trumpets you cant really get more than 45 ID

Indeed - but do you need a 50mm hole. Only guessing, but you probably need a 5L + engine reving north of 7k rpm to justify it - which is into high end wildcat teritory and therefore ££££££££.

I think this is the best solution:

Long runners and individual throttle bodies.

Edited by eliot on Sunday 13th March 08:44

Just seen this pic.. added after we went over the page I think... Like this a lot.... Who's is the manifold.. any ideas??..

[350Matt]

Think that's from JE engineering - should work rather well I'd say

What is this MOT / emissions rules tightening up? Dave referred to it earlier?

[eliot]

TVR Beaver said:

eliot said:

Alexdaredevilz said:

But with blending you could get say 50mm hole?

But with trumpets you cant really get more than 45 ID

Indeed - but do you need a 50mm hole. Only guessing, but you probably need a 5L + engine reving north of 7k rpm to justify it - which is into high end wildcat teritory and therefore ££££££££.

I think this is the best solution:

Long runners and individual throttle bodies.

Edited by eliot on Sunday 13th March 08:44

Just seen this pic.. added after we went over the page I think... Like this a lot.... Who's is the manifold.. any ideas??..

I posted on a sunday morning when my provider decided to upgrade his server - so people missed it.

Its from my manifold archive, Its a John Eales Manifold:
http://www.rover-v8.com/jeales/web.nsf/pages/used
£2770 !

Which is firmly in my "why bother - buy an LS3" department.

Edited by eliot on Tuesday 29th March 20:39