The V8 Owners Forum -

The intake plenum on a Thor RV8 is a "bannana" style with each side joined at the front with a cross pipe with the throttle body on on end.
This pic shows the cross pipe with the throttle body on the right.
You will note that the cross pipe has a larger diameter on the right and a smaller diameter to the left. I would have thought the cross pipe would have had the same diameter all the way across. Does anyone know why in theory air would be restricted a little to one side of the engine.

The reason I ask is that in my 101 engine bay there is very limited room on the passenger side and it would be good to have the throttle body on the left (drivers side) and putting it on the left (cutting the end off and welding on a throttle body mounting plate) but the inlet will be reduced in diameter.

As an alternative I could cut the right hand side of the cross pipe about 3" to the left of the throttle body and mount the throttle body there but I am not sure on what impact this would have with a shortened cross pipe.

Any throughts from the engine induction specialists?

This is a pic of my engine bay and you can see the right hand side has much less clutter. Thanks

Garry

No one with knowledge of a Thor RV8 on here?

garry

Educated guess, but I'd think it is to maintain velocity of the flow after the air for the right hand cylinders has been consumed.

Not actually an answer to the original question but if the basic issue is space on the passenger side of the engine bay, could you swap to a GEMS inlet and then rotate the top throttle body casting 180 degrees so it's on the drivers side. I'm pretty sure the bolt spacing will allow this.

garrycol wrote: ↑

Thu Mar 12, 2020 12:24 pm

No one with knowledge of a Thor RV8 on here?

garry

IMHO it's pretty good at what it sets out to achieve - a nice flat torque curve - out of the box, so not the same scope to tailor it for other things.

scudderfish wrote: ↑

Fri Mar 13, 2020 7:54 am

Educated guess, but I'd think it is to maintain velocity of the flow after the air for the right hand cylinders has been consumed.

Thanks for that - makes a lot of sense - I appeciate the thought.

richyb66 wrote: ↑

Fri Mar 13, 2020 8:10 am

Not actually an answer to the original question but if the basic issue is space on the passenger side of the engine bay, could you swap to a GEMS inlet and then rotate the top throttle body casting 180 degrees so it's on the drivers side. I'm pretty sure the bolt spacing will allow this.

Yes I had thought of that but GEMS is a rare beast in my country - with the exception of a few early P38s Range Rovers we did not get Gems here and have not seen any advertised for a long time. The other aspect is that I have two sets of Thor manifolds

DaveEFI wrote: ↑

Fri Mar 13, 2020 9:48 am

IMHO it's pretty good at what it sets out to achieve - a nice flat torque curve - out of the box, so not the same scope to tailor it for other things.

Yes I agree, and that is why I want to use it if possible - I have options concerning modifying the body but looking at alternatives with respect to the cross pipe but I do not have the knowledge to understand the ramifications of modifying or putting on a different cross plenum.

Thanks for all the comments - very helpful

Garry

thor manifold would be the best bet in a 101, gives more torque than the gems and previous hotwire plenums.
is it not possible to rotate the the thor plenum 180?

or get an elbow fabricated to rotate the throttle body 90'?

Easiest option as Eliot pointed out is to put a 90 degree elbow between the manifold and throttle body. It still on the same cluttered side but has more room.

If you need more space, cut the manifold flange off and weld a 90 degree elbow on the manifold. This moves the elbow towards the center.

Eliot wrote: ↑

Sun Mar 15, 2020 4:55 pm

is it not possible to rotate the the thor plenum 180?

or get an elbow fabricated to rotate the throttle body 90'?

No it is not possible to turn the intake runners around 180 as the runners will not line up with the holes in the lower inlet manifold.

However I had not considered taking off the throttle body and putting in a 90 degree bend - good thinking I will look at that

Thanks - great input

Garry

minorv8 wrote: ↑

Mon Mar 16, 2020 5:36 am

If you need more space, cut the manifold flange off and weld a 90 degree elbow on the manifold. This moves the elbow towards the center.

Like this - removing the blue shaded area?? Yes - thinking about it but a 90 bend might be a good option

Again thanks for the great contribution.

Garry

not sure you even need to cut the manifold up - there seems to be enough space to bolt the elbow to the end of the existing one?.
Jetex sell a very tight 90' in steel - you could weld flate plate to the ends and make it a bolt on.

https://jetex.co.uk/custom-exhaust-parts/products

The do them in 3" and 3.5" id.

I think you said you are non-uk, search google for "weld els" (welded elbows)
https://www.metals4u.co.uk/stainless-st ... gK9SPD_BwE

Used to make industrial pipework (and turbo manifolds)

Or SU elbows:
https://www.ebay.co.uk/i/254392218463?c ... gIbavD_BwE

Eliot.......how nice to see you

Hi - yep still alive!

Eliot wrote: ↑

Mon Mar 16, 2020 2:43 pm

not sure you even need to cut the manifold up - there seems to be enough space to bolt the elbow to the end of the existing one?.
Jetex sell a very tight 90' in steel - you could weld flate plate to the ends and make it a bolt on.

Thanks for that Eliot - no I am not in the UK - am in Australia so it is not cost effective to get the bends you linked but I am sure I will be able to source similar here.

Thanks

Garry

well you post me an LS3 from a Clubsport and i'll send a box of bends over...