The Great Trumpets vs Blended Base Debate...
Discussion
... and yes, I did search the Chim & Griff forums. 
A recap from what I found, trying to sense a general consensus:
A recap from what I found, trying to sense a general consensus:
- In terms of outright top end bhp, there's nothing between a carbon trumpet upgrade and a trumpetless blended base
- However, the trumpets offer a torque advantage compared to standard TVR trumpets all across the rpm range - I guess the blended base will mainly/only be advantageous at/near the top end?
- The gains using the carbon trumpets would be consistent and repeatable unless your handiwork is so dodgy that you can't even glue them in straight - however, achieving the right kind of 'flare' consistently across all intakes at home with a dremel tool may be a bit more of an issue; wouldn't this make the results utterly variable/unpredictable?
In my experience there's nothing to pick between them. The most powerful cars on my dyno have had blended bases (nearly 370hp with a blended base from a 5 litre? you betcha!) but they've also been in a higher spec as regards the rest of the engine too .. I've never seen any of the supposed midrange/driveability increases from using trumpets either, I personally suspsect it's one of those myths just like keeping your airflow meter gains you midrange. No doubt the people selling trumpets will have a different perspective, but at least you can then make your own mind up
As for blending the base yourself : you don't have to be skilled or consistent at all .. the only thing you need is to get as generous a radius on the base as possible but it doesnt have to be consistent, though it looks nice if it is and shows a pride in your work.
As for blending the base yourself : you don't have to be skilled or consistent at all .. the only thing you need is to get as generous a radius on the base as possible but it doesnt have to be consistent, though it looks nice if it is and shows a pride in your work.
If you are uning a high lift and long duration cam then I would think having blended bases as opposed to trumpets will allow most cross contamination of exhaust gases.. and you will notice this as less torque low down.. high revs may see slightly more power but as the gap between the top of the plemum and the blended base is greater than with trumpets - you miss out on the exhaust pulse reverberation - so the peak power may well actually be very sililar..
900T-R said:
Hmmm, interesting... cam is a Piper item bespoke to this engine... according to the builder it's actually got less overlap than the 214 that came out, but a fair bit more lift.
Below is a table that shows some Rover V8 cam specs :http://www.btinternet.com/~jon.wolfe/kentcamdata.h...
H214 Sports 1500 - 5000 11.90mm Inlet 12.44mm Exhaust 284 298 Degrees
H218 Sports 1500 - 5000 11.38mm Inlet 11.78mm Exhaust
278 284 Degrees
(SImilar to V8 dev's 404) .. I believe..
M248 Supersports 3500 - 8000 13.40mm Ex 12.85mm Inlet 300 Degrees
Hope that helps .. sounds like you cam is a sporty cam but not too wild..
rev-erend said:
L33 said:
My trumpets have blended bases and were part of the TVR Power "Taraka" upgrade.
Car goes like stink but I've never had carbon trumpets in to compare.
Surely you either have trumpets or blended bases .. you cannot have both..Car goes like stink but I've never had carbon trumpets in to compare.
Perhaps the guy meant blended bases?
L33 said:
rev-erend said:
L33 said:
My trumpets have blended bases and were part of the TVR Power "Taraka" upgrade.
Car goes like stink but I've never had carbon trumpets in to compare.
Surely you either have trumpets or blended bases .. you cannot have both..Car goes like stink but I've never had carbon trumpets in to compare.
Perhaps the guy meant blended bases?
"Blended trumpet-base", maybe .... 
I asked a similar question a few weeks ago then searched the said forums. I couldnt find a reason not to just shorten the existing trumpets when comparing price to power gains. at the minute ive taken the base out and am waiting for the good lady to go shopping for a few hours before I get use of her oven. So unless someone can convince me otherwise ill just shorten the original trumpets.
Reviving my old thread here... got a spare base and plenum (the latter of which Eliot will be hogging out to 72 mm 
) ... there's recesses of a larger diameter cast into the base around the outer four trumpets, so unless I have the intake manifold taken out and the holes machined out to 44 or 45 mm or so (on the 'other' side there's been some extensive proting to match the intakes on the heads so it's not just a case of swapping manifolds), I can't actually blend those without sleeving them first with some very thick walled tubing (in which case I'd as well take the easy route and shell out for some carbon trumpets)??
Anyone actually blended a 38 mm base?
) ... there's recesses of a larger diameter cast into the base around the outer four trumpets, so unless I have the intake manifold taken out and the holes machined out to 44 or 45 mm or so (on the 'other' side there's been some extensive proting to match the intakes on the heads so it's not just a case of swapping manifolds), I can't actually blend those without sleeving them first with some very thick walled tubing (in which case I'd as well take the easy route and shell out for some carbon trumpets)??Anyone actually blended a 38 mm base?
The outer 4 cross over, leaving them with a greater radius would seem sensible to me. Basically pipes with bigger diameter (st or curved) have less resistance, short small duct = long big duct in my simplistic understanding Trying to even out flow in the V8 is a black art (hence the unequal length trumpets), you can still try this with the blended base - just look at the uneveness of the manifold and try to balance it out. Apparently the Thor manifolds are different BTW.
Dave
Trying to even out flow in the V8 is a black art (hence the unequal length trumpets), you can still try this with the blended base - just look at the uneveness of the manifold and try to balance it out. Apparently the Thor manifolds are different BTW.Dave
OK, no going back now... roughly done one of the outer ports yesterday evening. My first impression is that like me you only have a Dremel tool rather than some kind or air grinder and - unlike me - you do have a life, just shell out the cash for the carbon trumpets.
I fully expect this to take a while and some grinding bits while it's at it - the one I used yesterday has run full with aluminium particles bakes solid into it already - will post pics later on.
Still not sure whether this was such a clever idea...
I fully expect this to take a while and some grinding bits while it's at it - the one I used yesterday has run full with aluminium particles bakes solid into it already - will post pics later on.
Still not sure whether this was such a clever idea...
900T-R said:
OK, no going back now... roughly done one of the outer ports yesterday evening. My first impression is that like me you only have a Dremel tool rather than some kind or air grinder and - unlike me - you do have a life, just shell out the cash for the carbon trumpets.
I fully expect this to take a while and some grinding bits while it's at it - the one I used yesterday has run full with aluminium particles bakes solid into it already - will post pics later on.
Still not sure whether this was such a clever idea...
Are you trying to grind the ally away with a grindstone? that won't work well , but you can ease the job by using lots of wd40 or similar to try and prevent it clogging .. I fully expect this to take a while and some grinding bits while it's at it - the one I used yesterday has run full with aluminium particles bakes solid into it already - will post pics later on.
Still not sure whether this was such a clever idea...
you really need to buy a proper carbide cutter and then you can do it with an electric drill or better still a drill with a flexi shaft attachment. Carbide cutters are about 30 pounds to buy and you'll be amazed how fast the ally comes off then!
If you do a nice job you could make some money doing blended bases for your mates at the car club? It should take you no more than an hour to do a complete blended base.
You can finish with stones,but keep dunking them in auto transmission oil to stop said stones from clogging(my porting 2 stroke days
)air die grinders with the burring ends remove the initial excess really well,and no i have not done my own yet
)air die grinders with the burring ends remove the initial excess really well,and no i have not done my own yetEdited by That Daddy on Friday 1st February 09:25
That Daddy said:
You can finish with stones,but keep dunking them in auto transmission oil to stop said stones from clogging(my porting 2 stroke days)air die grinders with the burring ends remove the initial excess really well,and no i have not done my own yet
Air grinders? Pah, in my two-stroke days it was rifler files )air die grinders with the burring ends remove the initial excess really well,and no i have not done my own yetEdited by That Daddy on Friday 1st February 09:25
Gassing Station | Chimaera | Top of Page | What's New | My Stuff