Induction manifold design

virgil · Post by **virgil** » Mon Apr 18, 2011 1:02 pm

Hello all. new here, so be gentle please

Looking to do some work on a TVR 500HC engine...new cam, new induction and after market EFI/Ingition

Looking to fabricate a less restrictive intake manifold with individual throttle bodies and plenum for feeding the engine 'cool' air piped from the front of the car. Not sure yet if short and near vertical stack (similar to existing manifold and trumpet base) or longer cross over with seperate plenums (similar to Cerbera AJP V8 ), but two main considerations with ITBs:

Air by pass for Idle Air Control - keep throttle butterfiles slightly open at idle, or incorporate a bypass valve with fully shut butterflies?

Vacuum for MAP and brake servo. 8 combiled pipes (V8 engine)

On OEM ITB installations I presume there is a 'collector' piped from the vacuum side of the ITBs for Vacuum for MAP and Brakes. Does anyone know what size the pipework is...I presume too small and reliable MAP signal is affected, too big and it must detract from the reason for using ITBs in the first place??

Cheers,

Virgil.

Eliot · Post by **Eliot** » Mon Apr 18, 2011 6:07 pm

Rover V8 induction has been done to death !
I have a large collection of photos on my Manifold page here:
http://www.mez.co.uk/ms12.html

The TVR Griff 500 systems work quite well once you use the ACT carbon trumpets and a 72mm throttle, along with removing the maf.

We recorded a minimal pressure drop inside the plenum at WOT - so we knew that there were no restrictions leading into the plenum - where as in stock trim you do loose about 5+ %

ChrisJC · Post by **ChrisJC** » Mon Apr 18, 2011 7:58 pm

You'll want to look at the heads too to be sure they are ported as far as you can go.

Chris.

virgil · Post by **virgil** » Tue Apr 19, 2011 10:23 am

Hi Eliot. Yep. Drooled over some of the pictures on your site many many times....great articles and collection of intakes you've put together.

The one regular thing that crops up (also on your site) seems to the restrictive inlet manifold (as well as crappy heads). I'm stuck with the heads (obviously can get them ported) but intake should be fairly easy to play with, no?

Pressure drop in the plenum at WOT is surely not measuring any restriction incurred at the manifold side...only upstream at the MAF, elbow etc?

A much less restictive inlet with a goodish head and a V8D H404 cam should give me what I'm looking for with a nice snappy throttle responce.

A choice between the very nice (but hideously expensive) JE cross over inlet (good for torque?) or a Wildcat near vertical, 20degree TB set up (good for ultimate BHP)...

The other option was to put the throttles on the intake under the trumpets (think one of the ones you had on your site was like this) but want to replace the inlet MF..unless someone tells me I;m absolutely wasting my time...

....and I'm itching to make something in composites!!!!!

virgil · Post by **virgil** » Tue Apr 19, 2011 2:22 pm

ChrisJC wrote:You'll want to look at the heads too to be sure they are ported as far as you can go.

Chris.

Are there any 'bibles' or guides out there for porting or is this really only a send off to a trusted party option?

ChrisJC · Post by **ChrisJC** » Tue Apr 19, 2011 3:15 pm

The hardest part is that the heads are ali, so finding a suitable burr is not easy.
I just cut up some heads to see where to remove material from. But there's nothing special.

I shortened the valve guides. You should also check that the port alignment between manifolds & head is good too, i.e. not a ferking great step!

Chris.

virgil · Post by **virgil** » Tue Apr 19, 2011 8:25 pm

ChrisJC wrote:The hardest part is that the heads are ali, so finding a suitable burr is not easy.
I just cut up some heads to see where to remove material from. But there's nothing special.

I shortened the valve guides. You should also check that the port alignment between manifolds & head is good too, i.e. not a ferking great step!

Chris.

like what you did there! not much material to remove then and shows perfectly how restrictive the port layout is...

Are these SD1 heads or 4.6?

spend · Post by **spend** » Tue Apr 19, 2011 9:04 pm

TVR 500 heads will already be heavily ported. Later versions just need the guides bulleting, many benefit from some extra valve de-shrouding, most have decent seat and blending.

You can grind near the flanges to blend into any manifold shape / direction you desire (even have the flanges built up with weld?) I think you need to be very careful changing the angle of delivery to the heads as there is a very cunning trapezoid shape + hump on the short side to promote swirl and it is very difficult to improve as well as being potentially made worse if the delivery at the flange is changed much?

Pete Burgess wrote a book on head porting and is well worth a visit if you need any work doing. Your heads would probably cost the best part of £2k to replace so if you aren't competent it would be a bit silly to mess them up.

ChrisJC · Post by **ChrisJC** » Wed Apr 20, 2011 6:51 am

virgil wrote:
Are these SD1 heads or 4.6?

They were either SD1 or Range Rover 3.5, I can't recall now. Definitely not 4.6 though!

Chris.

virgil · Post by **virgil** » Wed Apr 20, 2011 7:52 am

spend wrote:TVR 500 heads will already be heavily ported. Later versions just need the guides bulleting, many benefit from some extra valve de-shrouding, most have decent seat and blending.

You can grind near the flanges to blend into any manifold shape / direction you desire (even have the flanges built up with weld?) I think you need to be very careful changing the angle of delivery to the heads as there is a very cunning trapezoid shape + hump on the short side to promote swirl and it is very difficult to improve as well as being potentially made worse if the delivery at the flange is changed much?

Pete Burgess wrote a book on head porting and is well worth a visit if you need any work doing. Your heads would probably cost the best part of £2k to replace so if you aren't competent it would be a bit silly to mess them up.

What I thought...think i'll leave well alone...

virgil · Post by **virgil** » Wed Apr 20, 2011 7:53 am

ChrisJC wrote:
virgil wrote:
Are these SD1 heads or 4.6?
They were either SD1 or Range Rover 3.5, I can't recall now. Definitely not 4.6 though!

Chris.

Ok, cheers.

spend · Post by **spend** » Wed Apr 20, 2011 8:03 am

Pipe size to the 'collector' is only 1/8" on my Wildcats, remember as well that the hosetail is an even smaller restriction anyway. Idle air is also piped through that collector BTW. Map is better than in a plenum I would say, the plenum reading gets distorted by how close the sensor is to a particular trumpet.

I also have the purge valve plumbed into the 'collector', but mine works, no tank pops or extra stress on the fuel pump

:

virgil · Post by **virgil** » Tue Apr 26, 2011 4:04 pm

spend wrote:Pipe size to the 'collector' is only 1/8" on my Wildcats, remember as well that the hosetail is an even smaller restriction anyway. Idle air is also piped through that collector BTW. Map is better than in a plenum I would say, the plenum reading gets distorted by how close the sensor is to a particular trumpet.

I also have the purge valve plumbed into the 'collector', but mine works, no tank pops or extra stress on the fuel pump :

Great stuff. Thanks.
And the colelctor is just that...a box all the pipes come back into? Nothing fancy or clever??

spend · Post by **spend** » Wed Apr 27, 2011 9:27 am

Just a hollow 'box' with lots of hose tails, 14 on mine but I suppose teeing some opposing (by cycle) ports might be more sensible ?

virgil · Post by **virgil** » Thu Apr 28, 2011 9:49 am

spend wrote:Just a hollow 'box' with lots of hose tails, 14 on mine but I suppose teeing some opposing (by cycle) ports might be more sensible ?

Thanks.

Just out of interest, why 14? 8 for TBs Fuel reg, Map, servo...can't think of any more...