Fit your own trumpets...
Discussion
I'd though I'd start a new post now as they're almost finished. It may be useful to a few who are thinking of doing their own trumpets. Anybody got any ideas what glue would be best to glue them in?
Anyway, the trumpets were for a 48mm plenum base. Mine was from a Chimaera 500, so had a 44mm base as standard and therefore need boring out a little. As I wasn't boring out the intake manifold, I blended the internal diameter of the individual ports in the plenum base to retain the standard 44mm diameter at the bottom, but match the trumpet at the top. A kind of 'inverse flare' if you will.
Here's how I did it:
Firstly, get yourself a set of tungsten carbide bits and some grinding stones. The tungsten bits chew through the soft alloy and will do most of the work, whereas the finer bringing stones will help you remove the chamfered edges etc. I also used course and fine sand paper, together with metal polish to smooth down the surfaces. The shape of the tungsten bits are quite important. The flat topped cylindrical bit was idea grinding up to the lip in the plenum base where the trumpets sit. The chamfered bit allowed me blend the lip to the inner diameter of the trumpet. I tried with the arrowhead shaped bit a well. It cuts hard, but will also leave a rough finish. I would just stick to the two cylindrical bits if I was doing it again.
Once I had cut the base with the tungsten bits, I tried a single trumpet in each port and made fine adjustments. I then finished each port with a couple of grinding stones and a flapper wheel, before moving to sandpaper and polish. They're not 'factory' smooth, but pretty decent. Obviously, the smoother the better!
As for the trumpets, I stuck with the tungsten bits and the grinding stones to begin with. If I did it again, I would make straight and simple diagonal cuts between the centre four trumpets, not like the picture. The straight edge of the tungsten bit is very good for this and you can get quite a good edge on it. I think a rotary grinding wheel/ sharpener would also be good for achieving a uniform straight edge. As the trumpets are very thin and soft alloy, it is definitely worth taking it slowly and using grinding stones to remove the fine and smaller bits.
I began by removing a small amount and then marking where I wanted to cut, before trying for fit and grinding several times again. As with the plenum base, I sander and polished to remove as many marks as possible. I did this until I eventually got all the trumpets to fit. I then made a few adjustments to get them as close as possible and leave few gaps. It is quite time consuming, but also rewarding work and I would recommend anybody with some DIY skills to have a go themselves. The lower trumpet need to be fitted before the upper trumpets.
Before you fit, ensure you rinse everything several times to ensure you remove any fine bits of metal. The last thing you want is this being dragged into your engine! Remoember, before you glue them in, fit the plenum over the top to ensure they all fit!!!
I purchased the trumpets from here: http://www.ebay.co.uk/itm/261131985908?ssPageName=...
The tungsten bits I bought from here: http://www.amazon.co.uk/gp/product/B004WGJ5V8/ref=...
I used an air compressor and die grinder; however a decent Dremmel would probably do it, if not a little slower.
I have no idea how this will improve performance, but it must be better than the standard pipes. These were also 20mm shorter than the standard pipes. Something to bare in mind if you're concerned about low down torque. As the 500 has plenty, I wasn't too concerned and am under the impression that this moves the torque further up the rev range.
Hope his helps someone!
Standard trumpets (ram pipes)
Modified trumpets and base
Anyway, the trumpets were for a 48mm plenum base. Mine was from a Chimaera 500, so had a 44mm base as standard and therefore need boring out a little. As I wasn't boring out the intake manifold, I blended the internal diameter of the individual ports in the plenum base to retain the standard 44mm diameter at the bottom, but match the trumpet at the top. A kind of 'inverse flare' if you will.
Here's how I did it:
Firstly, get yourself a set of tungsten carbide bits and some grinding stones. The tungsten bits chew through the soft alloy and will do most of the work, whereas the finer bringing stones will help you remove the chamfered edges etc. I also used course and fine sand paper, together with metal polish to smooth down the surfaces. The shape of the tungsten bits are quite important. The flat topped cylindrical bit was idea grinding up to the lip in the plenum base where the trumpets sit. The chamfered bit allowed me blend the lip to the inner diameter of the trumpet. I tried with the arrowhead shaped bit a well. It cuts hard, but will also leave a rough finish. I would just stick to the two cylindrical bits if I was doing it again.
Once I had cut the base with the tungsten bits, I tried a single trumpet in each port and made fine adjustments. I then finished each port with a couple of grinding stones and a flapper wheel, before moving to sandpaper and polish. They're not 'factory' smooth, but pretty decent. Obviously, the smoother the better!
As for the trumpets, I stuck with the tungsten bits and the grinding stones to begin with. If I did it again, I would make straight and simple diagonal cuts between the centre four trumpets, not like the picture. The straight edge of the tungsten bit is very good for this and you can get quite a good edge on it. I think a rotary grinding wheel/ sharpener would also be good for achieving a uniform straight edge. As the trumpets are very thin and soft alloy, it is definitely worth taking it slowly and using grinding stones to remove the fine and smaller bits.
I began by removing a small amount and then marking where I wanted to cut, before trying for fit and grinding several times again. As with the plenum base, I sander and polished to remove as many marks as possible. I did this until I eventually got all the trumpets to fit. I then made a few adjustments to get them as close as possible and leave few gaps. It is quite time consuming, but also rewarding work and I would recommend anybody with some DIY skills to have a go themselves. The lower trumpet need to be fitted before the upper trumpets.
Before you fit, ensure you rinse everything several times to ensure you remove any fine bits of metal. The last thing you want is this being dragged into your engine! Remoember, before you glue them in, fit the plenum over the top to ensure they all fit!!!
I purchased the trumpets from here: http://www.ebay.co.uk/itm/261131985908?ssPageName=...
The tungsten bits I bought from here: http://www.amazon.co.uk/gp/product/B004WGJ5V8/ref=...
I used an air compressor and die grinder; however a decent Dremmel would probably do it, if not a little slower.
I have no idea how this will improve performance, but it must be better than the standard pipes. These were also 20mm shorter than the standard pipes. Something to bare in mind if you're concerned about low down torque. As the 500 has plenty, I wasn't too concerned and am under the impression that this moves the torque further up the rev range.
Hope his helps someone!
Standard trumpets (ram pipes)
Modified trumpets and base
They look very nice. Lets hope they have the desired effect.
When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
carsy said:
They look very nice. Lets hope they have the desired effect.
When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
What ECU are you running ..When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
They can't be any worse than the old TVR ones.carsy said:
They look very nice. Lets hope they have the desired effect.
When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
There was a web site that covered loads of different intake mods, one of which was a cutting board blended into the base (almost like a raised base that had been blended). Mixed results from it from what I recall. Would like to see some results from the one you've seen. Sounds interesting.When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
SILICONEKID350HP said:
carsy said:
They look very nice. Lets hope they have the desired effect.
When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
What ECU are you running ..When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
Sardonicus said:
o way on earth will you not notice an improvement the stock 500 pipes are bloody awful 
well done for doing your own thing 
Fingers crossed! I glued them in today and then realised that I hadn't put the bolts in!!! well done for doing your own thing 
I had to order a set of M8 manifold studs of Ebay.Either way, I picked up a riveter and put some new heat shield on the inner wings. Will hopefully get the exhaust manifolds back in tomorrow.
carsy said:
They look very nice. Lets hope they have the desired effect.
When i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
Here's the web site I was talking about (got mixed up between this and Blitz's G33 web). Loads of different intake mods on this page: http://www.mez.co.uk/ms12.htmlWhen i was at Jools Spitfire4v8 for mapping the other day he had a gorgeous looking blended base which he'd had manufactured. Although perfectly blended It was slightly taller than a standard base so had the effect of very short trumpets. Think he is going to start producing these. Wish i had taken a picture now. Maybe he will post one up.
yep this is the base. the trick is the radius on the inlet and not to let the length get too short as on a traditional blended base with two-pack araldite or chemical metal type stuff in the holes :shudder: . The gain is a clear 10hp at the top end with no losses low down compared to trumpets which is the important thing. other short inlets have lost lower down but not if you're careful about your design. also I was mindful of a comment about a plenum explosion that might have been due to puddling in the plenum on a nitrous RV8 drag car and wanted to make sure there were no voids such as with blending a std trumpet base. even after all these years with the RV8 there's still things to learn 
I have them made for me by a local firm. if youve already got short trumpets eg act ones then there's no point changing as they already flow loads of air, but if you're on std trumpets and want something that's really quick and easy to change over then a blended base like this makes perfect sense. You can make your own of course if you want to with chemical metal and a carbide burr in a drill but it's a bit of a faff unless you really like making lots of dust for a day and don't mind incurring the wrath of your wife as you stick your trumpet base in the oven.. 
That looks very cool indeed! C'est combien?
One thing I wanted to ask about blended bases is how does the change in the height of the middle four trumpets effect things? I assumed that the centre four trumpets were slightly taller, to compensate for the increased distances the air has to flow in the intake at cylinders 1,2,7 & 8?
One thing I wanted to ask about blended bases is how does the change in the height of the middle four trumpets effect things? I assumed that the centre four trumpets were slightly taller, to compensate for the increased distances the air has to flow in the intake at cylinders 1,2,7 & 8?
Edited by chris1972 on Tuesday 14th May 10:49
chris1972 said:
One thing I wanted to ask about blended bases is how does the change in the height of the middle four trumpets effect things? I assumed that the centre four trumpets were slightly taller, to compensate for the increased distances the air has to flow in the intake at cylinders 1,2,7 & 8?
I think that is a complete misconception. Just as the outer 4 manifold ports are obviously different from the inner 4, the outer ports are QUITE different 1 is nothing like 2 in the crossover (L vs SS IYSWIM) same for 7+8. The more constant rational that probably applies is the height of the inside of the plenum and throttle location. Edited by chris1972 on Tuesday 14th May 10:38
I think LR just used the long trumpets to maximize torque in a landcrawler, and whilst playing around (developing) / developing (playing around) added a quick'n'dirty shortening of the outside trumpets to try & accomodate the longer lengths in the inlet manifold; the bad air distribution in the plenum (central throttle); the domed heights within the plenum.
I've carefully measured runner lengths & volumes, height above trumpets to plenum in the past, and there is no correlation, they are all just designed as best effort then tweaked in testing IMHO. Ideas that some finite maths was applied to their design are probably just myth IMO.
phazed said:
It's all a bit of an art or pot luck!
To confuse matters more the Rover butterfly opens up bottom first iyswim.
When I reversed this with 2x54mm throttle bodies, I achieved 40 bhp less!
Thats largely the characteristic? of the upside down swan neck profile from the throttle sweeping up into the plenum.To confuse matters more the Rover butterfly opens up bottom first iyswim.
When I reversed this with 2x54mm throttle bodies, I achieved 40 bhp less!
As I've mentioned many times before in the past major gains from the ACT plenums are quite likely to come because they don't have to work with that oddball feature of the Rover plenum and have a much clearer path from butterfly into their plenums.
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