Shortest ITB trumpet length?
Thread Starter
10 Second Club
Joined: Nov 2007
Posts: 458
Likes: 2
From: Birmingham UK
Shortest ITB trumpet length? I am in the process of fitting Kinsler ITB's, i am restricted on space above them. I really need to run a trumpet straight out of the body just over an inch long.
Has anyone tried trumpets this short? The trumpets that come with them are around 4" long.
Has anyone tried trumpets this short? The trumpets that come with them are around 4" long.
Yikes!!! 30mm is really short! While the better breathing from the ITB stack will help as compared to a carb style intake, you're going to leave some torque on the table with the short stack length. The upper rpm range will work well though.....
Good luck,
Richard
Good luck,
Richard
Thread Starter
10 Second Club
Joined: Nov 2007
Posts: 458
Likes: 2
From: Birmingham UK
Here is an idea of what i am talking, the guy at Kinsler said i need 3 qtr's of the throat diameter as minimum clearance, throats are 55mm, so i need 41.25mm above the trumpet, i will try longer length when on the rolling road, just incase there are massive differences, but this length is easier to package. This is at the cardboard template stage, the base is now cut and box under construction.
The box volume will be in 12 ltrs plus, with two 4" cold air intakes.
With just the bodies on with no trumpets at all, this will idle down to 500rpms!!
Smooooth!
The box volume will be in 12 ltrs plus, with two 4" cold air intakes.
With just the bodies on with no trumpets at all, this will idle down to 500rpms!!
Smooooth!
Last edited by lstvr; May 30, 2010 at 05:11 AM.
Launching!
Joined: Feb 2004
Posts: 271
Likes: 0
From: California
Remember that your runner length is calculated from your intake valve, so what you are proposing may not be as bad as it seems (heck, what other choice do you have). Yes it is not ideal, but making them longer and then shrouding from the plenum is probably going to be just as bad. There are calculators/formulas on the web that can give you an idea of what RPMs are going to benefit from the pressure pulses for given runner lengths.
I would recommend the following course of action:
1. Dyno with the longer, or test a combination of runner lengths
2. Test your ideal packaged length and if you can live with the results then button it up.
3. If you cant live with the results, then either drop the motor (added benefit of lower center of gravity) or use a hood with more clearance (easier).
BTW. If you want to test how close you can put the plenum wall on top of the trumpets, use an aluminium plate with some adjustment screws and then adjust it down between dyno runs until you see a drop in peak HP.
I would recommend the following course of action:
1. Dyno with the longer, or test a combination of runner lengths
2. Test your ideal packaged length and if you can live with the results then button it up.
3. If you cant live with the results, then either drop the motor (added benefit of lower center of gravity) or use a hood with more clearance (easier).
BTW. If you want to test how close you can put the plenum wall on top of the trumpets, use an aluminium plate with some adjustment screws and then adjust it down between dyno runs until you see a drop in peak HP.
Trending Topics
Thread Starter
10 Second Club
Joined: Nov 2007
Posts: 458
Likes: 2
From: Birmingham UK
I have come to the conclusion i am going to have to power buldge it, so i will try the trumpets at around 60mm too, any more than this and the buldge will look a bit too hairy chest wig for my liking, plus the skuttle will need serious mods above this, i will try some plate and adjust it on some all thread, just to see if there is an optimum for plenum wall pulsing.
I will post my findings, will be in the next couple of weeks or so..
I will post my findings, will be in the next couple of weeks or so..
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
10 Second Club
Joined: Nov 2007
Posts: 458
Likes: 2
From: Birmingham UK
It sort of run out of puff at just over 6k, and the mid range was outrageous from 3-4K, so shoving peak power to nearer 7 would be desirable, but cam shunt was pissing me off, so was the main reason i bought these, if i get more power then thats a bonus too!
On The Tree
Joined: Mar 2010
Posts: 114
Likes: 0
From: Florida
itb stacks Why did you not use a cross over set up ? this would have give you more room to play with on your runners or stacks .If you take a look at what BMW did there air box this might help you sort out what you need to do with this .
Thread Starter
10 Second Club
Joined: Nov 2007
Posts: 458
Likes: 2
From: Birmingham UK
Heres the progress so far, the top will not be completed until dyno testing, but this will be straight forward. I just have to decide how long i can go on the trumpets and still package.
