Discussion
Hi, I have a Morris Marina 1800TC (BL B Series lump as found in MG B) which breathes using twin SU's at present.
Unfortunately I'm not able to mount any air-filters on directly due to the position of the body work and someone mentioned I'm loosing hp because of this - how?
I'm thinking of adding some air filters, the RAM Air look the easiest but what if I squash them to make them fit - will this matter?
If I manage to make a scoop to get cool, outside air into the SU's will this have any benefit? At the moment the SU's are mounted directly about the exhaust header.
Thanks.
Unfortunately I'm not able to mount any air-filters on directly due to the position of the body work and someone mentioned I'm loosing hp because of this - how?
I'm thinking of adding some air filters, the RAM Air look the easiest but what if I squash them to make them fit - will this matter?
If I manage to make a scoop to get cool, outside air into the SU's will this have any benefit? At the moment the SU's are mounted directly about the exhaust header.
Thanks.
Dont squash the filters mate! Itll reduce their ability to pass air, which is what youre attempting to improve upon.
Can you not have some sort of ducting that feeds to a remote air filter rather than having them directly on the side of the carbs? Or possibly modify the bonnet so that it has a bulge/vents maybe to accomodate the filters?
HTH.
Can you not have some sort of ducting that feeds to a remote air filter rather than having them directly on the side of the carbs? Or possibly modify the bonnet so that it has a bulge/vents maybe to accomodate the filters?
HTH. the restriction caused buy the air filter will alter the rate in which the piston in the SU carb rises and falls, as the draw from the engine increases this in turn will change your air fule ratio as the jet is fixed to the bottom of the piston. If the air fuel ratio is incorrect at certain revs you will not get max power.
docevi1 said:
Hi, I have a Morris Marina 1800TC (BL B Series lump as found in MG B) which breathes using twin SU's at present.
Unfortunately I'm not able to mount any air-filters on directly due to the position of the body work and someone mentioned I'm loosing hp because of this - how?
I'm thinking of adding some air filters, the RAM Air look the easiest but what if I squash them to make them fit - will this matter?
If I manage to make a scoop to get cool, outside air into the SU's will this have any benefit? At the moment the SU's are mounted directly about the exhaust header.
Thanks.
In most cases engines such as yours benefit far more by having been set up reliably than having 'uprated' air filters fitted.
I recommend that you fit a Piranha ignition system and make the carbs work better by fitting Grose jets in the fuel bowls.
Having the engine tuned on a rolling road will make it perform reliably to the best of it's ability and pick up power everywhere.
It may be possible for you to use a modified airbox and well fitting ducting to a large airfilter at the front of the car. But it is not a project for the inexperienced, and really as the filters will only give you power at the top end I'd look at improving the performance where you are driving 90% of the time.
thanks for the replies, so no air-filters at all (currently its running fine mesh across the front of the SU's) isn't something to worry about?
I'd figured squashing an air-filter would be a bad idea, but had to ask anyway.
I'd been looking at the air box idea, and there is no-where I can move it to. I can't mod the body work (insurance will go up again plus I can't do it myself). How long can the pipes be to the air-box be? I've just had an idea!
Why do you say adding Electronic ignition would be a good idea? Why is it that much better than the existing points?
I'd figured squashing an air-filter would be a bad idea, but had to ask anyway.
I'd been looking at the air box idea, and there is no-where I can move it to. I can't mod the body work (insurance will go up again plus I can't do it myself). How long can the pipes be to the air-box be? I've just had an idea!
Why do you say adding Electronic ignition would be a good idea? Why is it that much better than the existing points?
docevi1 said:
I'd been looking at the air box idea, and there is no-where I can move it to...... How long can the pipes be to the air-box be?
If you keep the pipe sizes as large as possible you can place the filter anywhere.
docevi1 said:
Why do you say adding Electronic ignition would be a good idea? Why is it that much better than the existing points?
Electronic ignition produces mutilple, fatter, sparks than your points. It also produces the spark much faster so can cope better with high revs.
Steve
deltaf said:
Arggh! No filters at all? Itll die the death from sandy particles! You Must put a filter on, its like you trying to breath in a dusty atmosphere; ie, youll eventually pack up! 
It hasn't had any on for 8k miles now
but I've had an idea which might just work. This is the engine bay at the moment:
I can only see two solutions:
1) Cut the body work. I don't want to do this due to the insurance rising & it takes away from the looks (although I go for function over form). I have thought maybe two bright silver pipes leading to an air box hidden elsewhere could look decent however.
2) Move the coolant resivour and put the air box there with pipes - it's directly above the exhaust so gets damned hot in there. Will this be a problem, is it better to get as cool air as possible in to the engine (Intercooler's work as they put much cooler air in, one presumes the air is superheated by the turbo?). This would be awkward in that the pipes to the carbs would be unequal length.
3) Get rid of the spacers on the heat sheild and put "normal" air filters on - this will result in vapour lock problems again tho.
Can anyone else see a potential solution? There is an electric petrol pump to be added...
You can get foam filters from places i think ITG and/or pipercross - check out Merlin Motorsport at Castle Coombe (i think) as they sent me a catalogue recently and there are some advertised. Useful for just your situation and they are advertised just for that purpose (and caterhams etc). A caterham solutioin actually is to cut the side panel there just big enough to stick the filters out - the Merlin Motorsport catalogue has such a picture. Worth looking at?
Ram air in its strictest sense isn't worth much for your set up because you are in danger of stuffing up ar flow into both carbs using only one air box, but it can work in principle. Roger Parker (MG technical guru) wrote a very good article on the B series, where it has been calculated that individual radial filters on the SUs (think the K&N type you would see on a B engine) are good for about a 3BHP increase over a type where the air would be sucked in straight in the throotle mouth. I can copy this article, if interested - provided i can find it!
If you went K&N or pipercross style, they are better flowing than normal paper types so are generally classed to give about 5bhp max over the normal MGB type filters. The best thing to do would be to get some ducting hose and point it at the carbs from the outside of the bay, but you really must put filters on before you do this or could power shoot dust, bugs etc into carb mouth!
I have just fitted elec ign when i supercharged my BGT and it is ok, but i am still somewhat jittery over relaibility. My theory on this however, is that brand new dizzy plus elec ign is a good combination, elec ign on a worn dizzy seems more likely to result in elec ign module failing . Unfortunately most people seems to sell elec ign modules as a "cure-all" for worn dizzies - and i don't think that is correct (most units i have heard of failing were on worn distributors!). I shall shortly be looking for a new dizzy!
FWIW also, i have been reading reports that grosse jets are having a poor reliability run and that are resulting in heavily over rich settings. Maybe just one batch though....
Finally do Marlin themselves not offer a solution? Surely they must have thought of this when the kit was designed...?
>> Edited by Buffalo on Friday 6th August 14:30
Ram air in its strictest sense isn't worth much for your set up because you are in danger of stuffing up ar flow into both carbs using only one air box, but it can work in principle. Roger Parker (MG technical guru) wrote a very good article on the B series, where it has been calculated that individual radial filters on the SUs (think the K&N type you would see on a B engine) are good for about a 3BHP increase over a type where the air would be sucked in straight in the throotle mouth. I can copy this article, if interested - provided i can find it!
If you went K&N or pipercross style, they are better flowing than normal paper types so are generally classed to give about 5bhp max over the normal MGB type filters. The best thing to do would be to get some ducting hose and point it at the carbs from the outside of the bay, but you really must put filters on before you do this or could power shoot dust, bugs etc into carb mouth!
I have just fitted elec ign when i supercharged my BGT and it is ok, but i am still somewhat jittery over relaibility. My theory on this however, is that brand new dizzy plus elec ign is a good combination, elec ign on a worn dizzy seems more likely to result in elec ign module failing . Unfortunately most people seems to sell elec ign modules as a "cure-all" for worn dizzies - and i don't think that is correct (most units i have heard of failing were on worn distributors!). I shall shortly be looking for a new dizzy!
FWIW also, i have been reading reports that grosse jets are having a poor reliability run and that are resulting in heavily over rich settings. Maybe just one batch though....
Finally do Marlin themselves not offer a solution? Surely they must have thought of this when the kit was designed...?
>> Edited by Buffalo on Friday 6th August 14:30
thanks Buffalo, the Marlin was designed before unleaded conversions were about (hence the higher running temps & spacers on the carbs) so I doubt they have a solution.
I'll give Merlin a call, if they sell Foam that'll have me very happy indeed
As for electronic ignition, that might be a winter improvement - it's working well as it is and I don't believe in fixing an unbroken thing
Thanks for the advice!
I'll give Merlin a call, if they sell Foam that'll have me very happy indeed
As for electronic ignition, that might be a winter improvement - it's working well as it is and I don't believe in fixing an unbroken thing
Thanks for the advice!
Was trying to post a pic of my s/c conversion because you could try having the a filter elsewhere and ducted to the carb as i have had to do for the reason of underbonnet temps....
Its poor quality because it was dark but also the only i have taken as yet. Might help though...
www.xpower-mg.com/gallery/showphoto.php?photo=9827
Its poor quality because it was dark but also the only i have taken as yet. Might help though...
www.xpower-mg.com/gallery/showphoto.php?photo=9827
I've just rang Merlin and they are sending me a catalogue, the version they have online looks as if it's going to be too big however.
here is a close up of the carbs
here When it comes to ducting, how big would it need to be? As you can see from the picture above there is very little space and I wouldn't get a wide pipe like yours in (nice engine bay!).
When I was across at a MOC event I saw this Would that work? I reckon I get someone to build something like that quite easily...
On another note, if I do cut a hole in the body work, will it not need to be significantly larger than the filter to account for the engine rocking or do the SU's not move about all that much?
Never thought to call Marlin, off to do that now.
>> Edited by docevi1 on Friday 6th August 14:43
here is a close up of the carbs
here When it comes to ducting, how big would it need to be? As you can see from the picture above there is very little space and I wouldn't get a wide pipe like yours in (nice engine bay!).
When I was across at a MOC event I saw this Would that work? I reckon I get someone to build something like that quite easily...
On another note, if I do cut a hole in the body work, will it not need to be significantly larger than the filter to account for the engine rocking or do the SU's not move about all that much?
Never thought to call Marlin, off to do that now.
>> Edited by docevi1 on Friday 6th August 14:43
In reality i suppose the pipe would be big enough to cover the throttle mouth. I have a little ram pipe thing attached to the carb mouth on mine which speeds the air up (supposedly) into the mouth and that is wide (90mm) hence size of my duct. The duct fully covers this mouth and the filter is down at the grille.
Its not ideal because of the length of pipe and the 180' bend at the top, but it runs cooler, so that is a good thing!
The pic you show there of the Marlin solution is good, but yours is far superior with the twin carb set up! It would be better to have the filter closer to the bonnet vents though, but again space may be your downfall here...
Its not ideal because of the length of pipe and the 180' bend at the top, but it runs cooler, so that is a good thing!
The pic you show there of the Marlin solution is good, but yours is far superior with the twin carb set up!
It would be better to have the filter closer to the bonnet vents though, but again space may be your downfall here... I'd be inclined to knock up a box similar to the Marlin one but bigger, more or less filling the gap between the front carb and the body, then run a length of Buffalo-style ducting either over the top of or round the back of the engine, to a large filter on the spark plug side where you've got plenty of room.
Hi Stefan.
Just had a look at your pictures.
A couple of things spring to mind, one of which is a different, shorter intake manifold. It may be possible to fabricate your own individual "runners" to mount the carbs on which would save some space.
The other thing you could do, if funds allow, would be an injection system, it dosent even have to be a new one. Just find something similarly sized and do a transplant.
You could even go the whole hog and swap the engine out for something a little more fruity, like a Vtec, a Zetec, Rs Turbo possibly....etc etc.
It seems that your having a lot of difficulty with space constraints and not really getting that much out of the current engine unit and thats why a swap/transplant could be the solution...just something to consider.
HTH.
Just had a look at your pictures.
A couple of things spring to mind, one of which is a different, shorter intake manifold. It may be possible to fabricate your own individual "runners" to mount the carbs on which would save some space.
The other thing you could do, if funds allow, would be an injection system, it dosent even have to be a new one. Just find something similarly sized and do a transplant.
You could even go the whole hog and swap the engine out for something a little more fruity, like a Vtec, a Zetec, Rs Turbo possibly....etc etc.
It seems that your having a lot of difficulty with space constraints and not really getting that much out of the current engine unit and thats why a swap/transplant could be the solution...just something to consider.
HTH.
First of some good news, I found a guy who used to fix mini's and what MGB's, popped up to see him and his response solved all my problems He suggested that I'm not having problems with "vapour lock" at all, but more that the needle inside the SU's are probably not the right ones. He also said he's got some short Spacer's which will give about 1/2" more space, which should be adequate to get Cone K&N's in. I'm heading up tommorrow for him to fiddle with and to see what solution he can come up with.
Deltaf I like that idea, I like it alot. Indeed I've thought about getting a RV8 in there but that'd be silly power IMO (at 70mph it's a little too fast already). Much more likely will be a MGB 2000 or 2100. The other engine designed for the chassis is the Alfa Twin Cam, but I quite like the MGB ties so will stick with that I think.
the problem with that is that I'll have to upgrade the drive-train, the rear axle, gearbox, prop-tunnel, brakes... (Assuming I go to a different engine, I'll need a new rear axle, 'box & better brakes for MG stuff I reckon) Ive just fitted a new prop so am loathed to buy another new one immediatly.
It's also the main reason I don't wish to start modifying the body as a new engine may be on the cards - I bought the car to learn, so rebuilding an engine to put in could be a great way to learn about that. It won't be for some years yet so getting the current setup right now is important.
He suggested that I'm not having problems with "vapour lock" at all, but more that the needle inside the SU's are probably not the right ones. He also said he's got some short Spacer's which will give about 1/2" more space, which should be adequate to get Cone K&N's in. I'm heading up tommorrow for him to fiddle with and to see what solution he can come up with. Deltaf I like that idea, I like it alot. Indeed I've thought about getting a RV8 in there
but that'd be silly power IMO (at 70mph it's a little too fast already). Much more likely will be a MGB 2000 or 2100. The other engine designed for the chassis is the Alfa Twin Cam, but I quite like the MGB ties so will stick with that I think. the problem with that is that I'll have to upgrade the drive-train, the rear axle, gearbox, prop-tunnel, brakes... (Assuming I go to a different engine, I'll need a new rear axle, 'box & better brakes for MG stuff I reckon) Ive just fitted a new prop so am loathed to buy another new one immediatly.
It's also the main reason I don't wish to start modifying the body as a new engine may be on the cards - I bought the car to learn, so rebuilding an engine to put in could be a great way to learn about that. It won't be for some years yet so getting the current setup right now is important.
Another little comment - when I squeezed pancake K&Ns onto the SUs on my Marcos I also got some stubby little ram stacks to help the air flow into the mouth of the carb - these little things fitted within the air filters. From your piccy, it looks like you have no trumpets or radiused stacks on the inlets. That sharp edge at the inlet IS NOT GOOD for the airflow. Your mini/MGB man should be able to advise you.
Best of luck
Best of luck
thank you very much for your advice. PH is once again top trumps!
www.moss-europe.co.uk sell most of the stuff I need as does mini spares
www.moss-europe.co.uk sell most of the stuff I need as does mini spares
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff