Correctable flaw in the 20v intake design?

[-GT-]

As said previously i think it's an application specific thing, ie if it's stock and just getting a tidy up, it probably makes no difference as it flows sufficiently well anyway, it's not the restriction in the system.

If you're going after 230hp though...

[SRacin]

Old thread. Still a good Topic. Still relevant to a couple of hp IMO. Threaded Rod with a bend re pictures above....? Im going to try just machine the crap outta the manifold and weld some new mounting lugs on. Should be ok.

[Sam_Q]

Still relevant indeed, apparently there is enough meat to machine the original manifold and bolt it up with slotted holes and angled washers.

[SRacin]

Definitely not as it pretty much needs a 20deg correction, but I figure 5deg is easily achievable without too much harm. My spare manifold is getting 5degs hacked off it at the moment. If it look like its going to be too much work to increase the machining angle and weld new tabs on, at least its 5degs less a wedge needs to be made to.

I think threaded rod bent into studs would be fine for clamping the thing up to the head.

[MorGo]

Anyone noticed that the "Silvertop" throttles open to something like 70º instead 90º?
The throttle linkage just hit the manifold and there is no way they will deliver the air they should be!
Plain desing flaw and probably the reason why Silvertops never did the promised power..

[Sam_Q]

Anyone noticed that the "Silvertop" throttles open to something like 70º instead 90º?
The throttle linkage just hit the manifold and there is no way they will deliver the air they should be!
Plain desing flaw and probably the reason why Silvertops never did the promised power..

I have only seen this when people have had the linkages mixed up, I have seen many throttles before and I don't think any had this problem.

[Sam_Q]

Definitely not as it pretty much needs a 20deg correction, but I figure 5deg is easily achievable without too much harm. My spare manifold is getting 5degs hacked off it at the moment. If it look like its going to be too much work to increase the machining angle and weld new tabs on, at least its 5degs less a wedge needs to be made to.

I think threaded rod bent into studs would be fine for clamping the thing up to the head.

correct me if I am wrong but up to a 7 degree angle change doesn't cause eddies or too much turbulence. I measured the angle change of the 20v intake to be 15 degrees. Now assuming all the above to be true you only need to take off 8 degrees.

[oldeskewltoy]

interesting topic... didn't see it back in 09.

I've recently seen a smallport(16V) head machined so the mounting points remain, yet about 1" of the port has been removed... custom made insert changes the flow to mimic a late F head or 20V head.... I'll try and get pics... if they let me

[Sam_Q]

I would be really interested in seeing pictures of that, it would be a bit limited on how much it could be corrected though.

Perviously I forgot to mention that I was reading in a book many years ago about people racing some old european engines with a very curved port. By chopping into the head and making it go straight they picked up a clear 15% gain with no other mods.

[e30-323ti]

I would be really interested in seeing pictures of that, it would be a bit limited on how much it could be corrected though.

Perviously I forgot to mention that I was reading in a book many years ago about people racing some old european engines with a very curved port. By chopping into the head and making it go straight they picked up a clear 15% gain with no other mods.

It wasn't this article re: Volvo BTCC cyl heads, which were significantly modified, but still considered 'standard'

Interestng reading...
page 1
page 2
page 3

[Sam_Q]

I don't quite understand how they managed to optimise the included valve angle but other than that they sure where sneaky. What a great read!

[MorGo]

I noticed the linkage misfit when adapting the Silvertop ITB's to customers 4A-FE.At first I think that I messed up something but it was clear that the throttle link hit the manifold way before the full throttle! Grinding about 5 mm from manifold and some from link the blades turn to 90º
Other solution would be thick spacers between throttle bodys and manifold but thats a lot of work.
This is factory stock intake so no modded parts..

Can't be that I am only one to find this!?

[Sam_Q]

can you take a picture of it for us?

[MorGo]

Ehh... I have to take the pic and then find how to get it in here.. Intake is still separate from engine so good pictures are possible.

[SRacin]

great article on the volvo. the factory black plastic gasket block thing has angle cut into it.