ledslinger

i've been doing homework on Injection and I got a serious desire to cast my own log style injection manifold. Im using Solidworks to make a 3D model to be printed out in ABS plastic, then make a mold and casting.

Is there any books about designing an intake?
any good books or threads on building your own injection system?
How do you determine runner length, and throttle body diameter, etc.?

I want to design it to function with or without forced induction, and the first one I make will be going on my 396.


this is the Idea that I'm goin with. I'm still getting dimensions off a factory intake, but want to know as much as I can through this project.

<a href="http://s22.photobucket.com/albums/b347/Factory4Speed/?action=view&current=IMG_20101015_133135.jpg" target="_blank"><img src="http://i22.photobucket.com/albums/b347/Factory4Speed/IMG_20101015_133135.jpg" border="0" alt="Photobucket"></a>

any input and advice is much appreciated.

Thanks
-Matt

The_Punisher454

From the camera angle its hard to tell just how long your runners are. I like the parallel pipe plenum, but I'd Siamese the two plenum tubes, your computer will be a lot happier. there is no power advantage at all to having separate plenums. You'll want to tune the runner length:cross section to the torque peak rpm you are looking for. Then you will want a large plenum volume upstream of the runners. On EFI too small a plenum will hurt power, while a large pleunum is good. Going "too big" is not nearly as much a problem as it is with carbs.
Also consider that your manifold breathes one cylinder at a time, this is very important. For an extreme example of this look at IR carb setups (one venturi isolated to each runner), on a V8 IR setup those 8 venturis would be WAY overcarbed if they all fed into a common plenum, but with the individual runners breathing through just one venturi each, you cant hardly make the venturi's big enough. Thats because only runner draws air at a time.
Anyhow, I like the two parallel plenum tubes, infact I have a 6 foot long piece of 4" diameter aluminum pipe saved for just such a thing. But I'd Siamese the two with about one or two inches of overlap.

For runner length, I'd start at about 10 inches for oval ports and a bit longer for rectangulars. I use "engine analyzer pro" from performance trends to test out ideas like this. It will allow you to do "chain" calculations of different runner length/diameter/plenum volume combination's(or most any other engine design parameter). Then you can look at the various HP/Torque curves and pick the one that suits you best. You'll quickly see that most of the time trying to optimize peak horsepower will result in major losses throughout the whole rest of the curve. What you really want is to have a lot of "area under the curve".

EApro software runs about $250.00 or so, but if you plan on doing this sort of thing very often then it would be a good investment. Dont make the mistake of confusing "Desktop Dyno" programs with "Engine Analyzer Pro", one is a seriously powerfull and detailed simulation tool, the other...not so much.

Orr89RocZ

iTrader: (20)

Most boosted style front fed intakes have a tapered plenum to even out distribution when under boost. Air comes in dense and fast so its hard to turn it right after the TB's. Plenum tapers down as it hits the rear cylinders. Suppose to help out distribution issues commonly seen in front feed TB applications like our cars, LT1's, etc.

If you would use that for both designs, i'd probably have a slight taper

vetteoz

iTrader: (13)

The definitive text
Dated in relation to modern intakes ( not much on EFI ) but same principles/ physics still apply

http://cgi.ebay.com/NEW-Scientific-D...item5d271ac746

Description: Over nearly fifty years, three editions and 20 impressions, this book has held its own as one of the best sellers in its field. This authoritative book will lead you through the complex theory to an understanding of how to design high-performance exhaust and intake systems for your own particular application. Join the many engineers, engine designers, high-performance tuners and racers who have depended on this book to develop the maximum potential from their engines.

Jacket notes:
Dr. John C. Morrison is one of the foremost authorities on the analysis of the induction and exhaust dynamics of high-speed engines. Together with Philip Smith, he gives a thorough explanation of the physics that govern the behavior of gases as they pass through an engine, and the theories and practical research methods used in designing more efficient induction manifolds and exhaust systems, for both competition and street use.

Chapter topics range from Simple Flow Problems and Sound and its Energy to Designing a System for Racing. This authoritative book will lead you through the complex theory to an understanding of how to design high-performance exhaust and intake systems for your own particular application.

Contents:

1. Basic Intentions
2. Simple Flow Problems
3. Sound and its Energy
4. Pressure Measurement Apparatus
5. Pressure Phenomena and their Application
6. Silencer Design
7. Designing a System with a Silencer
8. Designing a System for Racing
9. Induction System Design
10. Cylinder Filling
11. Modern Induction Practice
12. Valve Timing
13. An Analysis of the Induction Process
14. Exhaust Pollution Control

The_Punisher454

Awesome book! I've looked through it many times, but unfortunately I dont have a copy in my performance library (yet). Since I'm all about shortcuts, I usually use computer programs to calculate intake and exhaust runner length tuning. But that book has so much more than just the mathematical formulas, it really goes deep into theory.