Intake manifold and porting...

Intake manifold and porting...

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Discussion

Chuffmeister

Original Poster:

3,597 posts

136 months

Wednesday 10th December 2014
quotequote all
How far down did TVR port the intake manifold? My 500 is the standard 44mm, however, i'd like to know how far down the ports the ACT/ V8D 45mm versions are actually ported in comparison; or; how far the 500 44mm intake is ported in comparison to the standard 400 intake? Is it just the apertures of the ports that have been opened or have they been ported all the way down?

What would I need to do to my 44mm intake to make it the same as the V8D/ ACT intakes? earsscratchchin

Alexdaredevils

5,697 posts

178 months

Wednesday 10th December 2014
quotequote all
Can't answer the above

But my advice is don't do it you're self, I was covered in fillings for days it takes ages, you need to buy the proper tools

In this case I'd suggest buying one

Chuffmeister

Original Poster:

3,597 posts

136 months

Wednesday 10th December 2014
quotequote all
Cheers Alex. I've had an offer to open the ports to 45mm via CNC. I have a die grinder with tungsten carbide bits. Just wondered how much is CNC port opening and how much actual porting. If the ACT and V8D only have the ports opened and the rest as standard, then it is an easy enough job.

QBee

20,904 posts

143 months

Wednesday 10th December 2014
quotequote all
I was told that porting was two things:

1. Intensely boring and time taking and
2. A black art requiring years of practice.

Buy one ready done.

Alexdaredevils

5,697 posts

178 months

Wednesday 10th December 2014
quotequote all
Carbide bits will clog up after 30 seconds
You need the proper alloy ones
I got one you can borrow

I had mine opened up to 48mm but it was a one off, I got the video some where

phazed

21,844 posts

203 months

Wednesday 10th December 2014
quotequote all
I have an ACT one now and a V8D one on the old 4.6, both really good.

For the price, get a professional to do it, it's peanuts really.

Chuffmeister

Original Poster:

3,597 posts

136 months

Wednesday 10th December 2014
quotequote all
Thanks for the offer Alex. Is there any difference between the ACT ones and the V8D apart from the price?

I was considering having the 44mm CNC'd out to 45mm, but if it also needs porting to meet the same spec as the V8D/ACT ones, then its maybe too much grief. I did my own trumpet base and it took me a couple of afternoons, but if the intake needs loads of porting, then I may give it a wide birth.

phazed

21,844 posts

203 months

Wednesday 10th December 2014
quotequote all
Thinking about it, I believe the 5.5 is a V8D one as well.

Have a word with Rob, prices aren't too bad iirc.

Chuffmeister

Original Poster:

3,597 posts

136 months

Thursday 11th December 2014
quotequote all
Just sent him an e-mail.

spend

12,581 posts

250 months

Thursday 11th December 2014
quotequote all
All I have seen done is porting of each end of the manifold ~ not sure how a cnc would get on with tooling for the innards of the curly outer ports). That way they will only be @38mm with cast st (if the outers are opened correctly you can get long burrs & flap wheels in to smooth).

With regard to flow bench ~ did you look at the different flows on the different ports... you should be trying to equalize them (makes a bit of a mockery of cc'ing heads if the inlet is delivering different air ~ hence fuel proportions). This IMHO is most of the work involved in porting the manifold ~ trying to get the outer ports less restrictive & little done on the inner straight ports. After that you are just trying to get the CSA tapering down gradually to the valve ie minimize any sudden changes in direction/csa so it flows well.

When I've tried excessively ported manifolds I have been quite shocked how well they idle (the area where you think they might cause problems). I don't think having 42+mm (ALL the way with seriously lots of weld & grinding ~ work measured in years not hours!) has any negative effects apart from you may have to take more care with sealing to the heads and trumpet base (don't bother if not blended as you need the blend to get away from round and use oval/ovoid shapes to get into the manifold for big orifices!).

Sardonicus

18,928 posts

220 months

Thursday 11th December 2014
quotequote all
spend said:
All I have seen done is porting of each end of the manifold ~ not sure how a cnc would get on with tooling for the innards of the curly outer ports). That way they will only be @38mm with cast st (if the outers are opened correctly you can get long burrs & flap wheels in to smooth).

With regard to flow bench ~ did you look at the different flows on the different ports... you should be trying to equalize them (makes a bit of a mockery of cc'ing heads if the inlet is delivering different air ~ hence fuel proportions). This IMHO is most of the work involved in porting the manifold ~ trying to get the outer ports less restrictive & little done on the inner straight ports. After that you are just trying to get the CSA tapering down gradually to the valve ie minimize any sudden changes in direction/csa so it flows well.

When I've tried excessively ported manifolds I have been quite shocked how well they idle (the area where you think they might cause problems). I don't think having 42+mm (ALL the way with seriously lots of weld & grinding ~ work measured in years not hours!) has any negative effects apart from you may have to take more care with sealing to the heads and trumpet base (don't bother if not blended as you need the blend to get away from round and use oval/ovoid shapes to get into the manifold for big orifices!).
All of above really cool the end runners IMO are a bollo*ks to blend from a round to squarish transition and semi straighten I broke through the casting twice with the burr rolleyes the four inner runners are easy in comparison its all a big compromise to be honest, I have a 48mm blended base and intake all funneling down into the valve throats as best I could nerd I may be looking at running throttle bodies next winter purely for the better air distribution and road manners wink right now I just want my car functioning for spring whistle

Chuffmeister

Original Poster:

3,597 posts

136 months

Thursday 11th December 2014
quotequote all
Thanks spend/ Bobby. This is the type of technical stuff I'm after. Spend, in your opinion, what are the advantages of the standard 38mm, against the 44mm, against the 45mm? Is there any advantage of having the 45mm intake over the 44mm and what sort of power/ torque increase could you expect? Is there any advantage of either the 44/45mm over the 38mm if the porting is only done at each end?

Goaty Bill 2

3,393 posts

118 months

Thursday 11th December 2014
quotequote all
Tremendously good advice from all here I think.
I did a set of heads for my BBC many years ago. Granted they were cast iron, and a bit smile harder material, but it was a pig of a job taking days and days of 2-3 hours / day, and as spend has so correctly pointed out; it's as much about balanced flow, as more flow.
Experience in this area counts for far more than enthusiasm smile

The V8D offering looks good value for money to me.

spend

12,581 posts

250 months

Thursday 11th December 2014
quotequote all
Chuffmeister said:
Thanks spend/ Bobby. This is the type of technical stuff I'm after. Spend, in your opinion, what are the advantages of the standard 38mm, against the 44mm, against the 45mm? Is there any advantage of having the 45mm intake over the 44mm and what sort of power/ torque increase could you expect? Is there any advantage of either the 44/45mm over the 38mm if the porting is only done at each end?
Yes they probably remove 50% of the restrictive part... but lose efficiency where the air has to speed up to get through the (38mm) middle and slow down again where the port opens to the heads... As I tried to explain what you really want is a gradually accelerating air flow down to the head to get the maximum momentum behind the valve (vizzards 5'th stroke or whatever he calls it). Trying to do that whilst attempting to make all 8 cylinders fill equally is impossible IMHO so its a fine line... ~ yet folks still claim sequential injector control is only for economy confused - wink

Much depends on what spec the engine and its management is really...

Sardonicus

18,928 posts

220 months

Thursday 11th December 2014
quotequote all
~ yet folks still claim sequential injector control is only for economy confused - wink



[/quote] And emissions Dave hehe ................. but in my case essential wear for TB's scratchchin

spitfire4v8

3,990 posts

180 months

Thursday 11th December 2014
quotequote all
sequential injection doesn't really help here does it unless you have load/rev based individual trimming to go with it .. you need to fuel for the individual cylinder filling. Not that I think it would make enough difference to make it worthwhile.

Sardonicus

18,928 posts

220 months

Thursday 11th December 2014
quotequote all
spitfire4v8 said:
sequential injection doesn't really help here does it unless you have load/rev based individual trimming to go with it .. you need to fuel for the individual cylinder filling. Not that I think it would make enough difference to make it worthwhile.
Thing is you have un-timed injection with batch fire not exactly ideal especially running cams with long duration where you need all the help you can get scratchchin have that little squirt of fuel synced with cam duration/valve opening can only be a good thing, we are trying to keep cylinder firing/condition equal are we not? well best we can anyway frown

carsy

3,018 posts

164 months

Thursday 11th December 2014
quotequote all
Excellent thread and spot on info from Spend i reckon.

In relation to the outer ports not flowing as well as the inner ports, i have seen first hand evidence of this and up until reading spends post was scratching my head a little thinking maybe my injectors were not quite flowing equally but eventually dismissed this as both heads were the same. The ex valves on the inner two chambers were a slightly different colour than the outers, was the same on both heads. Evidence as spend says of the manifold runners not flowing equally.

I`m just about to have a go at a little inlet manifold blending. I`m going to use one of Jools`s 45mm blended bases as its a proven piece of kit, and my idea is to just open the top of the inlet manifold from 38mm to match this, blending it in the best i can. Not going to touch middle or head end of the manifold apart from checking port alignment. The idea being as spend says, start as big as possible and narrowing as it goes along. This in theory should speed up the airflow.

spitfire4v8

3,990 posts

180 months

Thursday 11th December 2014
quotequote all
Thing is you'd need very large injectors or very high rail pressures to get all your fuel into the chamber within the inlet open period (not even that, within the inwards gas flow direction period ..).
It's easy to do that on light throttle/low rev situations, but on full load (where inlet manifold flow rates become the factor we are discussing) you'd have to do the usual trick of setting the injector end point and increase the opening duration forwards from that, meaning the first part of the injected period will be well before the inlet valve has opened on high power cars. Most of the people I speak to who are in the aftermarket (ie not OE emissions / economy spec side of the industry) say it's not worth it. (You could run two sets of injectors (phased) near the head face I guess to shorten the injection period to something like what you need?).
Sounds a lot of work.

Chuffmeister

Original Poster:

3,597 posts

136 months

Thursday 11th December 2014
quotequote all
Very interesting info here and thanks for your replies.

Okay, so porting myself is over ambitious! So would upgrading my 44mm to a 45mm intake really make a difference to airflow? If you recall, I made my own trumpet base (see below). The trumpets have a 46.5ID and the base tapers to 44mm to match the mouth of the intake manifold. So would this help increase air speed or would the 44mm taper reduce air flow?confused

I'm planning on upgrading to MS. I have the larger bore induction stuff and a 72mm plenum on its way. I have made my own flared trumpets.

-With this in mind and for bang for buck, is it worth me upgrading my 44mm intake manifold to a 45mm?
-What gains would I likely see?
-The cylinder head port end of my manifold is already opened to stage 3 (being a 500). Would a wider mouth at the trumpet base end by 1mm make a big difference?
- Would my tapered trumpets not already increase the air speed in the same way as the large diameter intake mouth?

I appreciate that a lot of these questions may be difficult to quantify without a bench test/ dyno, but your collective experience is of a great benefit. I don't want to splash out £230 for a 1hp gain.