45mm inlet and Plenum base inc 72 mm throttle pot.
Discussion
Theory to be dissected. Feel free to comment no matter how bonkers it might seem.
Remembering my engine is a 4.6 With shorter stroke than 5.0so less suck. 400cc less
Is there any merit in making a blended base 38 mm bore into highly polished inlet into ported matched heads so you can move the power higher up but not lose the economy and low torque from the engine around town. By smoothing the line through the inlet your doing the job as much as increasing bore size. There is places of grab and bump points that can be worked on alone. If you smooth a stsndard inlet properly it must flow air far better and more of it. 5% is a lot in my eyes and it could easily be more. Flow bench needed!
It’s very simple in the bigger is better moto being basically true for raw power but I want that power distributed over a large window.
Plenum area is enlarged hugely by removing trumpets so available air is not a problem and charge and velocity should both be increased.
A large throttle body should supply enough air to fill Plenum so negative charge minimalised.
instant reponce should be better.
I have stsndard valves so until I’ve build heads
I don’t need more air than the engine requires but maximising it’s natural charge and flow. Shorter trumpets promote more air at higher revs so combining the blended base with 38/40 mm bore inlet might keep my engine in a good place. I’m reading about roof porting so I’ll try and do all the tricks and there’s no question you’ll get better flow characteristics with less restriction by simply smoothing out the bumps and rough casting marks which are through every port and serious s
t.
I’ve decided to try and make a manifold polished smooth to at least 600 grit. Every race head chamber and port you see is highly polished. Less swirl but far more charge which is what I’m looking for.
This also somehow includes an internally buffed Plenum too. If you reduce the surface bubbles down to micro levels it’s effect is similar to hardening the metal, I want the air to bounce off it and deflect back towards the engine.
This bit of the science seems to divide people. Some say inlets and ports should not be polished, others say polished to mirror. This is air being sucked in and all before fuel is added.
To my mind I want a combination of size better flow but still good velocity.
It’s not just 4000 revs I need the power, I still need it to be useable.
Q
Would a blended base into a 38 mm standard but polished inlet need a re map.
I have a map sensor.
Just thinking aloud and I’ll find out obviously but just thought I’d throw ideas out there.
Now that was wacky
Remembering my engine is a 4.6 With shorter stroke than 5.0so less suck. 400cc less
Is there any merit in making a blended base 38 mm bore into highly polished inlet into ported matched heads so you can move the power higher up but not lose the economy and low torque from the engine around town. By smoothing the line through the inlet your doing the job as much as increasing bore size. There is places of grab and bump points that can be worked on alone. If you smooth a stsndard inlet properly it must flow air far better and more of it. 5% is a lot in my eyes and it could easily be more. Flow bench needed!
It’s very simple in the bigger is better moto being basically true for raw power but I want that power distributed over a large window.
Plenum area is enlarged hugely by removing trumpets so available air is not a problem and charge and velocity should both be increased.
A large throttle body should supply enough air to fill Plenum so negative charge minimalised.
instant reponce should be better.
I have stsndard valves so until I’ve build heads
I don’t need more air than the engine requires but maximising it’s natural charge and flow. Shorter trumpets promote more air at higher revs so combining the blended base with 38/40 mm bore inlet might keep my engine in a good place. I’m reading about roof porting so I’ll try and do all the tricks and there’s no question you’ll get better flow characteristics with less restriction by simply smoothing out the bumps and rough casting marks which are through every port and serious st. I’ve decided to try and make a manifold polished smooth to at least 600 grit. Every race head chamber and port you see is highly polished. Less swirl but far more charge which is what I’m looking for.
This also somehow includes an internally buffed Plenum too. If you reduce the surface bubbles down to micro levels it’s effect is similar to hardening the metal, I want the air to bounce off it and deflect back towards the engine.
This bit of the science seems to divide people. Some say inlets and ports should not be polished, others say polished to mirror. This is air being sucked in and all before fuel is added.
To my mind I want a combination of size better flow but still good velocity.
It’s not just 4000 revs I need the power, I still need it to be useable.
Q
Would a blended base into a 38 mm standard but polished inlet need a re map.
I have a map sensor.
Just thinking aloud and I’ll find out obviously but just thought I’d throw ideas out there.
Now that was wacky
QBee said:
....as for runner length, 2/3rds of the length of your hall is about right, shows off the traditional parquet at the ends and sides just perfectly..... 
Found one for you - a tenner on my local buy and sell sight. Any similarity to a Griff owner’s chest wig is purely coincidental 
Charge and scavenging both work in the engines favour ideally as in the resonance pulsing effect of air going in and out. Faster charge Can build up the air pressure behind the inlet valves making it more dense so all this head bending stuff had to be carefully worked out for maximum power and EFFICIENCY.
I do my best thinking on here 
Sorry!
My peak torque and hp start at
3800 and 5000 revs respectively
This I believe is cam and timing as well as air flow.
I asked for a very torqy engine with good ecomony figures when having Mbe.
After market Ecu gurus
Adding air ( if it works) at the injector point more freely and using a map sensor.
Will the Ecu have the brains enough to compensate both fuelling and timing to suit and keep,AFR good or will it need a mapper too re configure settings.
Only thing being changed will be port matched standard but highly polished inlet with blended 38 mm base.
If at all possible I’d like to do it in stages so If I can do some of it without forking out on rolling road sessions thatbwould be good.
Sorry!
My peak torque and hp start at
3800 and 5000 revs respectively
This I believe is cam and timing as well as air flow.
I asked for a very torqy engine with good ecomony figures when having Mbe.
After market Ecu gurus
Adding air ( if it works) at the injector point more freely and using a map sensor.
Will the Ecu have the brains enough to compensate both fuelling and timing to suit and keep,AFR good or will it need a mapper too re configure settings.
Only thing being changed will be port matched standard but highly polished inlet with blended 38 mm base.
If at all possible I’d like to do it in stages so If I can do some of it without forking out on rolling road sessions thatbwould be good.
Classic Chim said:
I do my best drinking on here
Sorry!
My peak torque and hp start at
3800 and 5000 revs respectively
This I believe is cam and timing as well as air flow.
I asked for a very torqy engine with good ecomony figures when having Mbe.
After market Ecu gurus
Adding air ( if it works) at the injector point more freely and using a map sensor.
Will the Ecu have the brains enough to compensate both fuelling and timing to suit and keep,AFR good or will it need a mapper too re configure settings.
Only thing being changed will be port matched standard but highly polished inlet with blended 38 mm base.
If at all possible I’d like to do it in stages so If I can do some of it without forking out on rolling road sessions thatbwould be good.
EFASorry!
My peak torque and hp start at
3800 and 5000 revs respectively
This I believe is cam and timing as well as air flow.
I asked for a very torqy engine with good ecomony figures when having Mbe.
After market Ecu gurus
Adding air ( if it works) at the injector point more freely and using a map sensor.
Will the Ecu have the brains enough to compensate both fuelling and timing to suit and keep,AFR good or will it need a mapper too re configure settings.
Only thing being changed will be port matched standard but highly polished inlet with blended 38 mm base.
If at all possible I’d like to do it in stages so If I can do some of it without forking out on rolling road sessions thatbwould be good.
Very interesting observation I made.
Cam timing and specifically exhaust valve
Retarding the ign or having a cam with a short opening duration that leave exhaust gases still in the cylinder so when you try to re fill it with fuel and air on the next stroke there’s effectively less space. You reduce the cc available. It makes it more economical so can be a deliberate ploy.
Every theory can be questioned though it seems because what about the fact you’ve got a bad mix of air fuel and burnt gases so,less power!
I assume this is where retarding the ignition quickly when no load is present can help economy figures. Hmmm.
Cam timing and specifically exhaust valve
Retarding the ign or having a cam with a short opening duration that leave exhaust gases still in the cylinder so when you try to re fill it with fuel and air on the next stroke there’s effectively less space. You reduce the cc available. It makes it more economical so can be a deliberate ploy.
Every theory can be questioned though it seems because what about the fact you’ve got a bad mix of air fuel and burnt gases so,less power!
I assume this is where retarding the ignition quickly when no load is present can help economy figures. Hmmm.
Powers inlet manifold ( valley) gasket
Kindly Dom punched out the holes with his very impressive device to make it fit the biggest heads
Got an exhaust gasket for shaping of head ports.
There’s not much point starting with porting the inlet manifold if I haven’t got the heads off to match them.
So because and only because I have really cool Tvr friends and I really want to do this I’m getting some old standard heads so I can make a set of big valve and ported heads.
Or I might destroy them,,, hard to say at this point.
I have a car with Mbe so everything is easier to measure from a testing point of view.
At the risk of repetition it’s the heads that hold the breathing back regardless of inlet porting as it won’t make a jot of difference without better flowing heads.
So I’m after an old alloy head off any old crap to start learning how to dig and shape.
Wish me luck.
If I can gain 10-15 hp taking my car well past 310 possibly 320 hp I’ll be stoked.
I’ll enjoy doing it and I’m not inventing the wheel just more fine tuning a great car.
Velocity science is very interesting when you can see a gain from it.
I’m suprised COG doesn’t come on here and offer his advice.
Cam closed time duration and it’s effects on combustion etc let alone the possible flow rate benefits that are surely a performance and economy gain if done with sympathy.
Heads. First ones will be using biggest or near damn it valves that fit standard seats.
Nigh on what I have in my engine now. But they will also be ported and matched which mine are not.
As I have a standard Plenum and eventually a bored one I could try both back to back.
I’m sure even with heads and inlet opened up that extra air at the Plenum is really important for pressure Inside it.
I’ve yet to work out the flow rate of a standard inlet system to back of inlet valve and if someone knows what it is that would be good seem to,recall it’s about 150/165 ft
I think I have little choice but to get them flow tested if id want accurate before/ after results of CFM. Whatever we do with inlet runner on the o/e manifold it’s marginal gains at best but smoothing the passsge will speed up flow rate. It’s a given. How smooth to make the inside of the pipe is another question though
Kindly Dom punched out the holes with his very impressive device to make it fit the biggest heads
Got an exhaust gasket for shaping of head ports.
There’s not much point starting with porting the inlet manifold if I haven’t got the heads off to match them.
So because and only because I have really cool Tvr friends and I really want to do this I’m getting some old standard heads so I can make a set of big valve and ported heads.
Or I might destroy them,,, hard to say at this point.
I have a car with Mbe so everything is easier to measure from a testing point of view.
At the risk of repetition it’s the heads that hold the breathing back regardless of inlet porting as it won’t make a jot of difference without better flowing heads.
So I’m after an old alloy head off any old crap to start learning how to dig and shape.
Wish me luck.
If I can gain 10-15 hp taking my car well past 310 possibly 320 hp I’ll be stoked.
I’ll enjoy doing it and I’m not inventing the wheel just more fine tuning a great car.
Velocity science is very interesting when you can see a gain from it.
I’m suprised COG doesn’t come on here and offer his advice.
Cam closed time duration and it’s effects on combustion etc let alone the possible flow rate benefits that are surely a performance and economy gain if done with sympathy.
Heads. First ones will be using biggest or near damn it valves that fit standard seats.
Nigh on what I have in my engine now. But they will also be ported and matched which mine are not.
As I have a standard Plenum and eventually a bored one I could try both back to back.
I’m sure even with heads and inlet opened up that extra air at the Plenum is really important for pressure Inside it.
I’ve yet to work out the flow rate of a standard inlet system to back of inlet valve and if someone knows what it is that would be good
seem to,recall it’s about 150/165 ft I think I have little choice but to get them flow tested if id want accurate before/ after results of CFM. Whatever we do with inlet runner on the o/e manifold it’s marginal gains at best but smoothing the passsge will speed up flow rate. It’s a given. How smooth to make the inside of the pipe is another question though
The idea is to go to the inner edge of black lines then maybe another 1/2 mm towards the scribe marks which are the gasket position.
These ports are tiny!
Having looked at tonnes of stuff online these heads and inlet are just sooo small.
Better do a rough cut
I’ve looked at cross sectionals of heads, water gasket runs real close on some to the port short radius.
One move wrong and you’ve fked it..
I taking my time dude
Thing is I haven’t found a cross sectional of the a Rover head so caution
These ports are tiny!
Having looked at tonnes of stuff online these heads and inlet are just sooo small.
Better do a rough cut
I’ve looked at cross sectionals of heads, water gasket runs real close on some to the port short radius.
One move wrong and you’ve f
ked it.. I taking my time dude
Thing is I haven’t found a cross sectional of the a Rover head so caution
Classic Chim said:
I’m suprised COG doesn’t come on here and offer his advice.
It goes without saying if you want to maintain the same air fuel ratio and you introduce more air, you will also always need to introduce more fuel to match that extra air.Are you running closed loop?
If so it'll largely correct itself, well it'll correct itself when closed loop is operational and that is unlikely to be when the car is in the warmup phase, more importantly it'll also unlikely be in closed loop when warm and you're accelerating hard as in these circumstances it will be in open loop so referencing your fuel tables.
Do you have an AFR gauge and or have you got a laptop to plug in Alun?
Ultimately what you need to watch out for is the motor running lean under load (accelerating), that's what kills engines my friend!
If in doubt, get it professionally mapped... or better still learn the process yourself and save a fortune, it'll be a super rewarding process too. While you dont have a rolling road you can still achieve excellent results on the road, but a willing assistant helps a lot here as trying to drive and map the ECU on your own while driving on the public highway can be a very dangerous practice indeed.
Logs help but I tend to use FlashBack Express Recorder which is free screen capture recording software.
Alun whilst your at it your exhaust manifolds will most probably need opening up and matching your exhaust ports. They are a poor match from standard. There’s allegedly another good 10hp getting this right..
And as COG says try the mapping yourself, it’s very rewarding and addictive.. plus you save a few bob.
Good luck.
And as COG says try the mapping yourself, it’s very rewarding and addictive.. plus you save a few bob.
Good luck.
To late I’ve ruined it
Need single cut alloy bits, these are very aggressive.
Dress it up with the stones and a Polish.
Can’t just copy everyone so I’m going for a small shroud at the injector to swirl and flick the air into the centre of the chamber,,, hahahahahahah, just a craic really.
Same with ports, rectangular by design but I’m going to round them more as you might just see here.
Rough as fk but learning fast.
Need single cut alloy bits, these are very aggressive.
Dress it up with the stones and a Polish.
Can’t just copy everyone so I’m going for a small shroud at the injector to swirl and flick the air into the centre of the chamber,,, hahahahahahah, just a craic really.
Same with ports, rectangular by design but I’m going to round them more as you might just see here.
Rough as f
k but learning fast. carsy said:
Alun whilst your at it your exhaust manifolds will most probably need opening up and matching your exhaust ports. They are a poor match from standard. There’s allegedly another good 10hp getting this right..
And as COG says try the mapping yourself, it’s very rewarding and addictive.. plus you save a few bob.
Good luck.
Thanks guys, really appreciate it. And as COG says try the mapping yourself, it’s very rewarding and addictive.. plus you save a few bob.
Good luck.
Exhaust ports are at the end of the list
Thanks as I’ve been wondering about this.
I’ll be taking the whole car apart again,,, oh goodie. So I need manifolds off to bolt onto heads to work out where to blend better or do I just open and smooth out manifolds to be slightly bigger than head ports and be done with it.
I’ll tell you I’m addicted already. It’s damn physical work too!
Thanks for replying Dave and yes I’ll be looking much closer at the software side nearer the time.
Mostly I run closed loop but open WOT
So needs mapping.
I was watching Jason put a brand new 10 year old AJP crank in today, luckily I think they secretly approve and gave me lots of good advice.
I’m very lucky as an old friend runs his own machine shop too and he’s offered to show me and let me cut some valve seats in etc.
Got the machining sorted one way or another.
10 hp,,,,, from properly Flowing aligned exhausts.
No wonder we blow gaskets then!
Classic Chim said:
Late into the evening.
I’ll see you all next spring!!!
I haven’t got small enough stones so I’ll get more supplies.
Taking shape there Alun nice work I’ll see you all next spring!!!
I haven’t got small enough stones so I’ll get more supplies.
Edited by Classic Chim on Tuesday 20th March 13:54
OH Yeh here is that V8D manifold for you to screw at yep cobwebs and all 
been in storage , and note the satin/matt finish just what your after , polishing only for ex ports and not essential there either IMO 
Edited by Sardonicus on Tuesday 20th March 15:08
That’s quality work or what.
I’m never going to reach that level of accuracy but with a little practice and diligence I might still make a faster flowing pipe than what I’ve got.
No work
So did my chores and got on with some rough cuts.
Takes a very long time and I’m no where near but once I get some decent sanding discs in appropriate grits I should start to get them all evened up.
It’s ok with headphones on listening to your band practice recording
I’m never going to reach that level of accuracy but with a little practice and diligence I might still make a faster flowing pipe than what I’ve got.
No work
So did my chores and got on with some rough cuts.
Takes a very long time and I’m no where near but once I get some decent sanding discs in appropriate grits I should start to get them all evened up.
It’s ok with headphones on listening to your band practice recording
Edited by Classic Chim on Tuesday 20th March 16:35
Edited by Classic Chim on Tuesday 20th March 16:43
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