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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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#77 · (Edited)
the thing about that astra, is that the trumpets look like they have a sharp s bend in, and the total length looks like 20-25 cm, which is suited for 14,000 - 15,000 rpm.

not at all ideal for the engine's charactistics
 
#79 ·
plus the m3d'll do 4 extra injectors, which'll give you a nice top end boost.

oh, and they'll fully map it for 120+vat when you buy the ecu.

downside is you'll have to make your own loom. though i can see your eyes light up from here when you think about that ;) lmao
 
#81 ·
he's started pinking.... quick, wave some octane booster under his nose.

*waft*


that's better.

"Gary.... Gary.... Come back to us......"
 
#85 ·
just to clarify something fro,m my reply, the throttles on the astra are what loks like downdraught style ones. this means that the air has to go through a sharpish kink in order to get into the chamber. couple this with the overall length being about half of what it should be, and the engine won't make the kind of power it should. It'll still be strong, as it's a v6, but it will die off at high revs when compared to more suitably designed inlet tract (read longer and straighter).

one problem with fwd cars is that the engine sticking up through the bonnet doesn't look as good as on a rwd car, but that's just my opinion :p lmao
 
#86 ·
Animal said:
as it's a v6, but it will die off at high revs when compared to more suitably designed inlet tract (read longer and straighter).
Shoudn't it be shorter and straighter ?

I always thought:
The shorter the inlet tract, the more the max.torque goes up the rev band. :confused:
Shorter inlet tract, easyer breathing at high revs :confused:
 
#88 ·
OMG in a manta, you bloody loony!!

can just see the tech spec now

ENGINE
3 litre omega engine
gas flowed and ported heads
homemade manifold to run 6 throttle bodies
home brewed exhaust

SUSPENSION
quaife ATB diff

GEARBOX
quaife straight cut

INTERIOR
stripped and caged
2 buckets seats
ECU
battery
toilet paper for passenger!



















can i get a ride when your done? please??
 
#89 ·
Photo's

hmmm... i'm not sure about the suspension, tbh.

But on to other things.

Photo's.


1. Pistons

on the left, we have an early XE Piston, a forged Mahle jobbie. the v6 one is cast, heavier, has much bigger valve pockets, and is slightly dished.





 
#90 · (Edited)
next on the bench, we have the exhaust headers.

what a crap design, well for power. Ditch the recirculation, and drop on some less restrictive tubular manifolds, and some cams with a load more overlap than the std efforts, and it'll be a much happier engine.



 
#91 ·
Totally Blocktastic Mate

Here is the beast. It doesn't feel much heavier than the std 2.0L block, but when it's built up, it'll be at least 30-40 kg's heavier.

 
#92 ·
Now the interesting bit.

This is the 2 heads connected together by part of the original induction system. It's not too evident from the photo that the ports aren't a uniform distance apart from each other, so each of the Throttle Bodies is going to have to be angled away from each other.



This is the std induction. looks about ripe for modification, until you measure it and find out that the diameter is about 35mm, whish is way too small. bugger.



Not very useful, i was trying to show the difference in heads, but i'll clean em up next time....

 
#96 ·
Yeah but Emerald can make you a "it'll just about work" startup map if you give them some engine info. And there's little point in going custom ECU unless you get it optimised on rolling road.
Know what you mean though.
 
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