Trumpets VS Blended base

Alexchim · Post by **Alexchim** » Mon Sep 26, 2011 4:34 pm

What is the truth?

I have 45mm trumpets at the moment, and I just cant see how they would be better than a good smooth blended base like this http://www.mez.co.uk/rovermanifolds/DSCF3587.JPG

Surely the air coming in would just hit the trumpets making the air rough inside?

Oppose to air coming in and straight to the required hole .

I know the theory is they give more torque but does any one have proof of this?

I have seen the dyno prints from ACT but you have to remember there selling them so it will be biased.

Thanks

Alex

Post by **katanaman** » Mon Sep 26, 2011 4:53 pm

Yes trumpets work but it all depends on the state of tune of your engine. In general the longer the intake the lower and higher the torque will be. The length of the trumpets should ideally be worked out for the requirements of the engine. Having a blended base might be an advantage on some engines (high revving) but a disadvantage on others. Landrover took it further with long cast tracks on the thor manifolds but then the engines were for large low revving engines in heavy cars.

Its not just about getting air in, its also about keeping the fuel air charge where it should be and the longer trumpets are better at holding the reverse pulses in.

Make any sense? Google tuned induction for better descriptions than I could ever give.

Eliot · Post by **Eliot** » Mon Sep 26, 2011 5:00 pm

I've got a graph somewhere showing that ACT 45mm trumpets performed slightly better than my blended base. Both of which are better than the stock TVR straight pipes, which is better than the stock 37mm effort.

Alexchim · Post by **Alexchim** » Mon Sep 26, 2011 5:44 pm

Its a 4.6 with all the goodies 305ish dur mechanical cam

I will be going megasquirt or some thing else in a few months and i have a LT1 throttle body(2x52mm) to be welded on my plenum soon

Am I wasting my time going blended? im not that bothered about torque i want it to rev to 6500 well with max bhp

daxtojeiro · Post by **daxtojeiro** » Tue Sep 27, 2011 6:14 am

I blended my old 5.0L TVR engine and noticed no difference what so ever. According to V8D the larger trumpet base is the best option, I have that on my new engine.
I've also done a lot of tests on the 74mm plenum and that gives a restriction of 5% to my 5.4L engine. I plan on making a larger plenum and a triple inlet (triumph bike throttles) similar to the ACT plenum but bigger
Phil

kokkolanpoika · Post by **kokkolanpoika** » Tue Sep 27, 2011 11:42 am

http://mez.co.uk/ms12.html

Update: Testing has shown that the blended base isn't as effective as the short carbon ACT trumpets (~10 bhp down).

I think siamesed plenum has got same effect..

Eliot · Post by **Eliot** » Tue Sep 27, 2011 8:14 pm

kokkolanpoika wrote:http://mez.co.uk/ms12.html

Update: Testing has shown that the blended base isn't as effective as the short carbon ACT trumpets (~10 bhp down).

I think siamesed plenum has got same effect..

Thats right. A guy called clive had them dyno'd back to back, i have a copy of the dyno sheet somewhere.

POAH · Post by **POAH** » Wed Sep 28, 2011 10:13 am

is that a peak gain or is it through out the rev range?

kokkolanpoika wrote:http://mez.co.uk/ms12.html

Update: Testing has shown that the blended base isn't as effective as the short carbon ACT trumpets (~10 bhp down).

I think siamesed plenum has got same effect..

Wotland · Post by **Wotland** » Wed Sep 28, 2011 1:57 pm

MK1 blended base was made for me but in my case for SC engine.

spend · Post by **spend** » Wed Sep 28, 2011 4:21 pm

Eliot wrote:
kokkolanpoika wrote:http://mez.co.uk/ms12.html

Update: Testing has shown that the blended base isn't as effective as the short carbon ACT trumpets (~10 bhp down).

I think siamesed plenum has got same effect..
Thats right. A guy called clive had them dyno'd back to back, i have a copy of the dyno sheet somewhere.

That dyno test was of your plastic insert version vs ACT trumpets, and didn't impress the tester very much at all as I recall. I wouldn't take it as being necessarily indicative of all blended bases as the said dyno owner subsequently fitted a blended base in his own 500 engine?

Eliot · Post by **Eliot** » Thu Sep 29, 2011 8:52 am

spend wrote:
Eliot wrote:
kokkolanpoika wrote:http://mez.co.uk/ms12.html

Update: Testing has shown that the blended base isn't as effective as the short carbon ACT trumpets (~10 bhp down).

I think siamesed plenum has got same effect..
Thats right. A guy called clive had them dyno'd back to back, i have a copy of the dyno sheet somewhere.
That dyno test was of your plastic insert version vs ACT trumpets, and didn't impress the tester very much at all as I recall. I wouldn't take it as being necessarily indicative of all blended bases as the said dyno owner subsequently fitted a blended base in his own 500 engine?

Ended up in a moaning session as CF wanted his money back (£80) - as it didn't work as well as they expected. At the time I had no idea if they worked, so no guarantees were made - so i said no.
Here's the graph for the plastic blended base againt act carbon trumpets - not that bad, when compared to the price of carbon trumpets imo.

And no i'm not making any more, i've done them for the pure interest - not for comercial gain. They take me hours to make, as its all done by hand on the milling machine. Someone with a CNC could pump them out in seconds.

spend · Post by **spend** » Thu Sep 29, 2011 9:10 am

It was a kind of nice idea for an easy bolt in mod... but assuming it to be equivalent to a properly flared base & inlet manifold (ie with a nice flare - not just a radius on the mouth) is not at all representative IMHO.

With your ability to port a base & inlet I'm sure you wouldn't expect the insert to perform as well would you Eliot? ie I'd be very surprised if you equated all blended trumpet bases to that one trial development as it appears this thread has suggested.

kiwicar · Post by **kiwicar** » Thu Sep 29, 2011 9:13 am

Hi
I take it that was on a rolling road dyno not an engine dynamomiter. I think I would have trouble arguing I could accuratly measure less than 3% differance in OP on a RR with the figures taken atleast 30 minutes apart . . . . I certainly would want barometric pressure engine, 'box and axel temperatures ambiant humidity readings for each run. I would still argue that 3% was within measurment error unless I had half a dozen runs on each set up.
What makes me even more skeptical is that I cannot concieve changing inlet tract length by about 40mm would make 3% differance in output of an engine producing about 65 BHP per litre, there is no way that engine is in that delicate state of tune, 165bhp per litre I might just accept it but 65. . .

Sorry but I think the reality is that the radiused set up is pretty well as good as a set of fancy carbon fibre trumpets, just they don't have the bragging rights.
Best regards
Mike

Eliot · Post by **Eliot** » Thu Sep 29, 2011 10:11 am

spend wrote:It was a kind of nice idea for an easy bolt in mod... but assuming it to be equivalent to a properly flared base & inlet manifold (ie with a nice flare - not just a radius on the mouth) is not at all representative IMHO.

With your ability to port a base & inlet I'm sure you wouldn't expect the insert to perform as well would you Eliot? ie I'd be very surprised if you equated all blended trumpet bases to that one trial development as it appears this thread has suggested.

Not quite following what you are saying. But the upshot (and i think we are agreeing) is that proper flared trumpets perform the best.

spend · Post by **spend** » Thu Sep 29, 2011 12:17 pm

I don't think we are agreeing at all?

Your plastic piece WAS NOT a flared base IMO. The sides were parallel and aligned with the existing trumpet base + inlet manifold standard runners, with simply a radius turned in the plastic at the top. A gradual cross section change by flaring down the inlet tract (just about similar to what the superflare trumpets do above) is quite possible when you grind the base out carefully, with welding it can be improved even more to quite extreme flares 'in the base' as well as removing the limitations of a round bore.. What I am saying is that your particular plastic invention cannot be taken as an accurate evaluation of flared + blended base designs, which should all defined by the fact they have a 'flare' as distinct to just a radius at the entry?

Jamie at CRE made a flared manifold & base for a mate which out-performed nearly every other base on Joos dyno.. Subsequent evaluation has led me to believe that the extra work flaring way down into the inlet manifold was the key to that power advantage (alongside a solid cam..) I should come clean that I have both sets of manifolds & bases from both Clive & Paul sat in my garage for posterity, and they have both been improved upon. Equally clear in my mind from personally seeing Joo test your 'interesting idea' of a drop in base is that it has no relevance to flared & blended bases at all and was just a 'thinking out of the box' innovation that more importantly highlighted that simply rounding the base mouths was pretty much a waste of time?

Hence I think it is of absolute importance to distinguish whether the blended bases have been flared or not, and that only rounding the entry is a complete waste of time, money & effort?