Velocity stacks lenght question

[LAC99]

I want to buy the toda straight trumpets (air horns, velocity stacks or whatever you want to call them) but I don´t really know which length I should get. They have 30 and 55 mm for the silvertop 4ag.
I have standard camshafts, custom 4-2-1 header, 11:1 compression and a port & polish job. Blacktop ECU and MAP. Everything else stock.

When I tried 63mm trumpets I felt more medium range torque but less high end power than with the stock parts so I want to shorter ones but I don´t want to lose to much medium range torque if I go with the 30mm

Do you know if there´s any dyno chart or something I can check out to compare the power/torque curve with different trumpet lengths? what experience do you have with different lengths? Is it best to use the horns with or without the air box?

thanks,

Luis

[Ozone]

I doubt you'll find Dyno plots with different length trumpets.
Other parts fitted to the engine will have an effect so every engine with these trumpets fitted will have a different effect.
I don't know how much they are but you could buy a set of each, try them both and sell on the ones you don't want.

The airbox should make a big different to induction noise but litte/no difference to power.
However you might find aftermarket trumpets do not fit in the airbox anyway.

BTW do you know the length of the standard trumpets?

[gon]

the only way to actually know is to test both with YOUR engine in the dyno.

But from what I have read the 20v likes short trumpets in almost all RPM's .... (due to the fact that the distance from the itb end to the valve is quite long already.)

[Project D]

short trumpet -> power (high rev)
long trompet -> torque (less power)
depend of how you drive

[Celica RA45]

i have a mate who races with me and his ram tubes in his black top 20 v are about 75mm long ,his engine is std and with a ae86 exhaust manifold attached to the engine as well .with his own mandrell secondary header pipes
this motor idles and makes max power at 7800 and rev cut at 8200 rpm
so i would start with a longer 1 and go from there

[byd1380]

Where can you buy them from? I run mine with no trumpets and just a pipercross filter fitted, I don't have room for the standard ones.

[Eircamae86]

@ last post http://www.technotoytuning.com very good, quick postage to Ireland

[LAC99]

those are 75mm long!! toda´s longest trumpets for silver top are 55mm. I think I´ll stay with the TODA lengths.
I´ve found a guy here that makes trumpets for a much lower price though so i´m getting the 30mm and 55mm and then straight to the dyno to end this discussion.

this is the page with all the TODA trumpets specs

http://www.toda-racing.co.jp/en/product/...4ag-3.html

[LAC99]

byd1380 Wrote:Where can you buy them from? I run mine with no trumpets and just a pipercross filter fitted, I don't have room for the standard ones.

take a look at this link, they have distributors in england

http://www.toda-racing.co.jp/en/link/link.html

[jondee86]

Quote:I´ve found a guy here that makes trumpets for a much lower price
though so i´m getting the 30mm and 55mm and then straight to the
dyno to end this discussion.

Ha !!! The best length for trumpets is a never ending discussion As
soon as you fix the length, it means that the effect will be most felt at
a certain rpm due to the tuned effect of the inlet tract. A different length
will be more effective at some other rpm range. And each person has
a different goal for their engine.

For this reason there is a lot of development on variable length trumpets
that change length while driving, according to the rpm and load on the
engine (like VVTi). Also, there are some people who say that the BT and
even the ST throttles are too big for a 1600cc engine. This results in an
engine that is biased towards high rpm, and does not produce much
power down low.

I will be interested to see the curves you get on the dyno... good luck

Cheers... jondee86