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Designing your own TB's.

6K views 107 replies 29 participants last post by  Animal 
#1 ·
Designing you own TB's.

evenin' all.

Having aquired a (soon to be un-mullered) 3.0L v6, I'm having a stab at building some tapered tb's for it. Sounds ambitious? Well it would be, except for a couple of key things.

the heads are basically the same as the 1.6 16v, except for having 3 cylinders per head.
the cylinder cc is the same as the XE (bore is 86mm, stroke is 85mm)

The main problems are that there's **** all space, as you've got to try and fit 6 tb's in the space 3.5 tb's normally fit in, and that the bonnet is going to have to be extended up so that the induction system will be long enough.

The basic paramaters are:

45mm throttles (sourced from heavily chopped varijet2 carbs)
throttle plate will be approximately 200mm from the inlet valves
overall length will be 35-40cm in length
each cylinder will have 2 injectors, one in the trumpet, one in just past the throttle plate. It'll use either all XE cream injectors or bottom ones V6 upper ones XE Cream)

I'm prototyping it using plastic (white chopping boards) as it's easy to cut and very cheap. Final system will be a mixture of aluminum and fibreglass.

It'll be controlled by an emerald ecu, as it's much cheaper than the alternatives, and can do everything that's needed.

The exhaust manifolds will need to be fabricated, as the std headers are dire (the 3 exhaust ports each side are connected together with a cast iron box). Which will be fun. again, the XE and 1.6 manifold design are available, and coupled with a few informative books on exhaust design, I'll have a field day with it!

The rev limit of the v6 can be approx 7750, as the stroke is similar to the XE, and ARP rod bolts will fit.

If the 1.6 16v can make 164bhp on TB's with std cams, i should be able to get 280-300 bhp if i can get the TB design correct and the manifolds effective.

I've looked into getting some cams made for it, and i'll need to get them cut from billet as blanks aren't available, so it'll end up costing about a grand :eek: for a set of 4 cams.... still, if the 1.6 can make 190 from the 284/278 cams, then the v6 could make 320 - 330 Bhp ish with 240ish ft/lb.

Understand that these figures are very ball park, and were obtained by dividing bhp by cc, then multiplying by the new cc then taking some off, to try and take into account the valve areas (The 1.6 has much more valve area which will help it at higher rpm).

Photo's to follow..........
 
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#53 ·
update

measured it all up.

dist from back of valve to ports 85mm
dist from ports to butterfly 115mm
dist from butterfly to start of trumpet 100mm
trumpet length 100mm

total 400mm ish which is exactly was wanted.

and best of all, it all fits (according to a quality cardboard mockup i prepared earlier), and i won't need to curve before the butterfly.

so it'll look like this!

 
#56 ·
if possible, i'm going to make it out of aluminum, and where possible, i'll do the machining, as there isn't much of it, mainly gasflowing of the internals. I'll probably get a local engineering place to weld what i need.

if aluminum proves to be a problem, then i'm gonna resort to either fibreglass or mild steel
 
#61 ·
:D Interested in any information people have about about converting DCOE's ;)

Secondly, I found lumenition to be fairly cheap for their programmable ECUs. I've been mucking about with their software and it seems pretty good.

Trouble is they charge seperately for the software to program it :(
 
#62 ·
#63 ·
the engine in the chevette i think is a chevy as the morosos rocker covers are fairly common for chevys, also there is a bigger following for chevy engines and parts are therefore cheaper.

the longer the intake runners the better for torque but harder to set up. chevy did do a V8 that had 30 inch intake runners (the carbs actually sat above the rocker covers/ex headers area) although it was dropped after a year as the mechanics had so much trouble setting it up right, but when right it gave huge gobs of torque low down.

from the pics it looks like your going for a cross ram set up. shame it's not going into a manta then all you need is a cowl vent, probably a chopped up one from a corvette to cover it all up
 
#64 ·
the emerald ecu is about 600ish inc vat s/w cable etc, then it's 120+vat flat rate to get it mapped, regardless of how long it takes.

why did i ever buy a mbe?

cheers for the articles, I'll have a good read.
 
#65 ·
Cool thread....:cool:
Animal: Be interesting to see how u get on with ur manifold. Got some math somewhere for designing intakes if ur interested.

Ghost_Walker: Yeah, that's a chevy small block. Looks like its got a Lingenfelter SuperRam intake on there with the old 1000 cfm throttle body job. Turbos look huge too. These sort of twin turboed setups on small blocks can easily make 1000hp+ and are often seen powering salt flat racers for top end runs. Would be frightening to have that sort of power in a shovette.:eek:
 
#66 ·
em i'm not a anorak!! just a tefal head!!hehe, just pure guess work really

Lingenfelter = stupid power from standard looking cars. saw a program on him once. his work is amazing, he actuall had a corvette that put out double the power of a standard one all through the rev range and used less fuel. apprently it all comes down to the map and how well the cylinder head is designed
 
#67 ·
I've been called an anorak before.... and I guess it's true.

what was worrying though, was it was Gary calling me an anorak. Man, that's serious anorak territory!
 
#69 ·
Having just returned from the scene of some incredible goings on, i.e. the loft Mr. Animal all I can say is.... Oh My God, this thing is gonna be mental!

Matt talked through the plans and although there is a lot of one-off work to be done his enthusiasm is going to see this through and if it doesn't then he's going to get a kick up the arse!! ;) lmao
 
#70 ·
Just one quick question.........

Ya know that Astra with the V6 and TB's.... if (ignoring the physical limitations) it had much longer trumpets.... would it perform much better????

If so..... what sort of difference would we be talking???? :D

Also...... how much do Wrecked Omega V6's go for these days?? :D :D ;) :rolleyes:
 
#71 ·
I've seen what matts enthusiasm + a drill big enough for British petroleum, can do to a poor 1.8 head ;)

scary stuff when he gets going - he's an amalgam of me, Tom stickland, the embittered spirit of Genghis Khan, and Kato (of inspector clueso fame) lmao

btw matt, I'm waiting for delivery of Dave Walker engine management book, courtesy of a CCC subscription - it comes with the Emerald mapping software on CD (hehe...jewelleryjewellery) - you want me to copy you off one ? :cool:
 
#75 ·
oh, you can download the software from emerald's site, but the cd one has a 'virtual engine' built in.

i reckon you'll be sorely tempted to upgrade to emerald.....
 
#76 ·
Ya know that Astra with the V6 and TB's.... if (ignoring the physical limitations) it had much longer trumpets.... would it perform much better????
Total induction length dictates the power curve on an engine. If you stick long ones on it should produce more torque, shorter and it will produce more bhp. Forumlar one cars can extend theirs comming out of corners for more low down power. The Omega V6 lump is built to produce lots of low down torque so naturaly would benifit a lot more from a long induction length than a revvy four-pot would. However if the plan is to start camming the V6 to rev a lot then you can bring the induction length down.

It really comes down to how you wish to drive the car, TB's such as the SBD ones are tailored to the kit car racing scene therefore are designed to produce lots of bhp and the power band is all at the top end as when racing on a track you spend most of your time at high revs.

For a 'streetable' engine you would get more 'performance' from longer trumpets, especialy on a V6.
 
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