Porting Induction side (45mm) - BUT with standard Heads
Discussion
Sorry if this has been answered before - but as usual the search is giving me nothing of use!
My questions is about porting and in particular what gain (if any) do you get if you do the following...
1. Ported Inlet manifold to 45mm on both ends.
2. Ported Trumpet Base to 45mm with either alloy or carbon trumpets.
3. Install a 72mm plenum or ACT carbon plenum.
BUT without changing anything to do with the heads.
I have a 3.9 standard engine with ACT induction kit to the AFM and then smooth bore elbow to plenum and also superflare trumpets.
Will the fact that the heads being standard make the above installation pointless?
The reality for me is I'd like to do induction side now in preparation of going to Stage III heads later on.
Thanks
Mark
My questions is about porting and in particular what gain (if any) do you get if you do the following...
1. Ported Inlet manifold to 45mm on both ends.
2. Ported Trumpet Base to 45mm with either alloy or carbon trumpets.
3. Install a 72mm plenum or ACT carbon plenum.
BUT without changing anything to do with the heads.
I have a 3.9 standard engine with ACT induction kit to the AFM and then smooth bore elbow to plenum and also superflare trumpets.
Will the fact that the heads being standard make the above installation pointless?
The reality for me is I'd like to do induction side now in preparation of going to Stage III heads later on.
Thanks
Mark
OK,
to put this in perspective..:
I did exactly what you have mentioned - but I have the benefit of having TVR BV heads on a tuned 4.6.
My overlaid graph is below (red/before - blue/after)..:
As you can see it made very little difference - moved the torque curve up the RPM scale slightly, and increased torque marginally, to create an improvement of about ~10BHP
And this is with TVR BV heads..!
The problem is that I have hit the max flow of the heads, and making these changes does very little, as you will not be addressing the bottleneck itself.
I am upgrading my heads even further to remove this bottleneck and get the full benefit of the upgraded intake components - my gut feel is that your heads will be the biggest bottleneck too, and the money may well be better spent on the heads first, with small incremental improvements to the intake components upstream in the future...
AIMO - HTH,
Dom
to put this in perspective..:
I did exactly what you have mentioned - but I have the benefit of having TVR BV heads on a tuned 4.6.
My overlaid graph is below (red/before - blue/after)..:
As you can see it made very little difference - moved the torque curve up the RPM scale slightly, and increased torque marginally, to create an improvement of about ~10BHP
And this is with TVR BV heads..!
The problem is that I have hit the max flow of the heads, and making these changes does very little, as you will not be addressing the bottleneck itself.
I am upgrading my heads even further to remove this bottleneck and get the full benefit of the upgraded intake components - my gut feel is that your heads will be the biggest bottleneck too, and the money may well be better spent on the heads first, with small incremental improvements to the intake components upstream in the future...
AIMO - HTH,
Dom
please explain to me?
are we talking cylinder heads?
i know im thick, but if we are talking cylinder heads, what do they have to do with a ported inlet manifold which is not near the cylinder heads, i realise i could do my credibility irreversible damage, but i dont understand.
i have a set of ported inlet manifolds plenum sandwich and insulator ready to go on one day, and i thought i knew what the point of that was, now im not so sure.
i already have the larger plenum and afm fitted
Lester
are we talking cylinder heads?
i know im thick, but if we are talking cylinder heads, what do they have to do with a ported inlet manifold which is not near the cylinder heads, i realise i could do my credibility irreversible damage, but i dont understand.
i have a set of ported inlet manifolds plenum sandwich and insulator ready to go on one day, and i thought i knew what the point of that was, now im not so sure.
i already have the larger plenum and afm fitted
Lester
OK, erm...
The intake manifold is the thing that sits in the vee between the cylinder banks.
The ports on the cylinder head side need to match up with the intake ports on the head.
The ports on the other side need to match up with the trumpet base on top of it.
Those are the basics.
Then, you want the ports big enough to not pose a restriction at the maximum air flow rate the engine manages to pull through them (= max power), but not so big that the air speed into the engine drops below the point where the fuel starts to (literally) drop out of the air fuel mix. There is a balance to be struck there, and unsuprisingly the amount of air your heads will flow is at the start of the decision path about what to put on top/in front of the engine.
The intake manifold is the thing that sits in the vee between the cylinder banks.
The ports on the cylinder head side need to match up with the intake ports on the head.
The ports on the other side need to match up with the trumpet base on top of it.
Those are the basics.
Then, you want the ports big enough to not pose a restriction at the maximum air flow rate the engine manages to pull through them (= max power), but not so big that the air speed into the engine drops below the point where the fuel starts to (literally) drop out of the air fuel mix. There is a balance to be struck there, and unsuprisingly the amount of air your heads will flow is at the start of the decision path about what to put on top/in front of the engine.
Eric, i hear what you are saying, but i think i will have another look under the bonnet before i try and understand, i dont quite see how the plenum sits on top of the heads in between the Vee, it seems much too large. i will see if i can find an exploded view somewhere. Thanks for trying
Lester
Lester
spooky, ive just seen this advert on pistonheads
its very pretty and it looks like it means business and would do the business
but i am no nearer understanding :-)
http://www.pistonheads.com/sales/4034181.htm
think i understand now,
i have the parts in pictures 7 + 8 and a loom and a new fuel rail with new injectors that have been "matched for flow?"
i now see where it sits in relationship to the V, are the heads we are talking about under the big silver bit, or is the big silver bit the heads?
Lester , ace mechanic
its very pretty and it looks like it means business and would do the business
but i am no nearer understanding :-)
http://www.pistonheads.com/sales/4034181.htm
think i understand now,
i have the parts in pictures 7 + 8 and a loom and a new fuel rail with new injectors that have been "matched for flow?"
i now see where it sits in relationship to the V, are the heads we are talking about under the big silver bit, or is the big silver bit the heads?
Lester , ace mechanic
Edited by lestershaw on Wednesday 4th July 08:09
yes thats what i have ,
does that mean the heads are underneath that lot and that something has to be done to the heads to make it go better, or is all the work done on the parts in the photo you just posted?
i hope so because the parts i have are already ported, polished etc and ready to go ( thanks Eric)
does that mean the heads are underneath that lot and that something has to be done to the heads to make it go better, or is all the work done on the parts in the photo you just posted?
i hope so because the parts i have are already ported, polished etc and ready to go ( thanks Eric)
Best way to see is to take an intake gasket and see how it matches up on either side (heads and manifold).
My guess would be that the modded intake manifold would be ported to match the intake gasket, but the heads wouldn't - which would mean a step from the big ports in the manifold to the smaller ones in the head would be in the way of airflow and bugger things up. Which would be no good.
In that case, the only option is to take off the heads and match the ports to the ones in the manifold (again using the gasket as a template) - but really, then you'd be better off having the heads professionally ported/upgraded, or buy a pair of upgraded exchange heads from one of the usual suspects.
If the head ports are bigger than the ones in the manifold, that's not so bad - roll on with the install.
My guess would be that the modded intake manifold would be ported to match the intake gasket, but the heads wouldn't - which would mean a step from the big ports in the manifold to the smaller ones in the head would be in the way of airflow and bugger things up. Which would be no good.
In that case, the only option is to take off the heads and match the ports to the ones in the manifold (again using the gasket as a template) - but really, then you'd be better off having the heads professionally ported/upgraded, or buy a pair of upgraded exchange heads from one of the usual suspects.
If the head ports are bigger than the ones in the manifold, that's not so bad - roll on with the install.
haircutmike said:
Lester, this conversation has me very worried and concerned for your car.
loli wouldnt do anything myself
my son in law is Tom from track classic sports cars (tcs birchanger, check his portfolio) and has his own rolling road, and i take my car to snibs at hilton and moss who are less than a mile away from where i live. i wouldnt dream of doing anything to it myself, the kit i have came off a 5.0 chimaera engine, but mine is a healthy 290 bhp at the moment and i wont be contemplating doing anything while its running well. im just trying to understand how it all works, rather than just get in and press the loud pedal
haircutmike said:
Dom, your 10 BHP increase, did you change the cam?
On my 4.6, when I changed to Stage 4 heads, and all that you have done + a Typhoon cam, (that was already fitted) I got about a 50 BHP increase and loads more revability!
No - no cam change (although the cam had been replaced about 5000miles prior to the upgraded inlet components going on).On my 4.6, when I changed to Stage 4 heads, and all that you have done + a Typhoon cam, (that was already fitted) I got about a 50 BHP increase and loads more revability!
My TVR BV heads have the big valves, inlet porting, and some exhaust porting - but apparently not as much exhaust porting as the 500 BV heads. I am wondering whether I have the BV heads off a 4.3..?
I have a set of Pete Burgess-ported BV heads going on now, which have noticeably more porting on the exhaust ports (unsure about inlet) - so I'm hoping that will enable more flow and extend the torque curve further up the rev range, as the torque drops off very quickly at the moment...
Dom
Gassing Station | Chimaera | Top of Page | What's New | My Stuff