LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently November 19, 2017, 11:44 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: January 18, 2017, 10:13 pm 
Offline

Joined: January 5, 2010, 12:13 pm
Posts: 18
Location: Little Rock, AR
I was on the site looking for other information, and after looking around, thought a project that I did a few years ago may be of benefit to those that want a unique LS fuel injection option that would be more affordable than the typical aftermarket offerings. My goal was an 8-stack EFI that would fit on my LS2 mid-engine project, but be low cost. Seeing $4k and above for most set-ups, I set out to fabricate my own, but without the benefit of a machine shop. All I had was a heavy-duty drill press, and lots of hand tools.
What I ended up with was this:

Image

Major parts used were;
1) A cut up and re-welded Idelbrock Pro-Flow intake manifold.
2) 8 Chrysler LHS 3.5L throttle bodies (they are Holley 48mm bodies with one vacuum port, and a throttle shaft...very simple) from the salvage yard.
3) Various pieces of plate aluminum for mounting plates and adapter plates.
4) Hardware bits and pieces from McMaster Carr.

In the end I had about $800 in the actual intake system, and then additional money for the fuel management and aluminum ram-tubes. A photo sequence of the work, and captions explaining the photo are located at:

http://toxandale.fototime.com/Manta%20ITBs

_________________
Terry
Cardomain photos

BlueOvalZ photo documentation
Image


Last edited by blueovalz on January 19, 2017, 12:23 pm, edited 2 times in total.

Top
 Profile  
Reply with quote  
PostPosted: January 18, 2017, 11:02 pm 
Offline

Joined: September 22, 2005, 10:29 am
Posts: 398
Very interesting. How does it perform?


Top
 Profile  
Reply with quote  
PostPosted: January 18, 2017, 11:11 pm 
Offline
Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
Posts: 5747
Location: SoCal
kreb wrote:
Very interesting. How does it perform?

This. A back-to-back comparison to the OEM LS3 intake manifold and throttle body would be very informative.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Top
 Profile  
Reply with quote  
PostPosted: January 18, 2017, 11:26 pm 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 2869
Location: Under the weather. (Seattle)
I love it! :cheers:

In my opinion: As long as it's not massively down on power, if it provides the right look, feel, and sound to go with the car, then it serves its purpose...And if it does happen to offer some gains, all the better.

_________________
-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)


Top
 Profile  
Reply with quote  
PostPosted: January 19, 2017, 9:10 am 
Offline

Joined: February 8, 2014, 10:47 pm
Posts: 427
Location: Cornholio OR "Where the magic happens"
Too many detractors on ITBs.

Synchronization
Idle quality
Idle control
Throttle response
Power loss

The biggest being power loss due to the disturbance of airflow by the butterfly.
The science behind induction systems is to accelerate the air smoothly from the entrance of the tract to the valve.
Air should be admitted at a larger diameter and steered towards it's destination smoothly,
on it's way it should be gently squeezed and accelerated so a column of air is rammed into the cylinder.
Given this the cross sectional volume of a runner should be gradually reduced without any variation that might take away the energy of the mass of moving air in the column.
A butterfly valve placed at the bottom of the column disrupts this flow and dramatically reduces air speed.
During my time helping with the R&D on a patented 2 roller air valve, I have seen on a flow bench as much as a 20% loss in flow caused by a butterfly valve.
This results in the need for oversized runners and TBs to make up for the flow loss,
however velocity is permanently lost and velocity is the key to ramming in more air than the piston can suck.

The rest of the issues with ITB's make tuning and driving difficult.
It is very difficult to modulate ITBs, they feel like more of an On Off switch.
A consistent idle speed is next to impossible to maintain.
With that Idle AFRs will be all over the place.

I could go on but the first point is easily proven on a flow bench or Dyno and results in a thumbs down for the ITB.
If this was a good idea it would be found on most all production motors.

Many equate ITBs "performance" due to ITBs almost uncontrollable tip in.
Their butt dyno pegs from the hit and they are so impressed they completely miss the missing power part.
The inrush flow on a butterfly valve is huge and when you have 4 6 or 8 of them (usually oversized to make up for flow loss)
the inrush is so big you are at 1/2 total airflow at 1/8 butterfly rotation.
This is the same effect as installing a Super E Carb on an Ironhead, the carb is way too big and by the time your arms snap back into their sockets
you don't realize that from 3/4 to full throttle there is no difference in power.
But your butt dyno is happy even though Im going to beat you in a race with a tiny 38mm round slide carb.

But for eye candy there is nothing better!

_________________
Feels like I'm on the last train,
rolling on cracked wheels,
and Hillary is the engineer!


Last edited by Bent Wrench on January 19, 2017, 10:10 am, edited 3 times in total.

Top
 Profile  
Reply with quote  
PostPosted: January 19, 2017, 9:45 am 
Offline
User avatar

Joined: September 22, 2005, 8:12 am
Posts: 1347
Location: 4AGE in S.E. Michigan
Terry
Thanks for sharing. You differntly have one hell of a project going there.
Dave W


Top
 Profile  
Reply with quote  
PostPosted: January 19, 2017, 10:24 am 
Offline

Joined: January 5, 2010, 12:13 pm
Posts: 18
Location: Little Rock, AR
Bent Wrench wrote:
Too many detractors on ITBs.

Synchronization
Idle quality
Idle control
Throttle response
Power loss


Sychronization - is very good here, but it took some work for that. I'm not sure slight differences in castings of intake manifolds or a/f distribution would be any better in a non-ITB set-up.

Idle quality - as good as any OEM intake or program. The fuel management system has more to do with this than the ITBs do. Current day fuel management systems offer a large variety of inputs. Idle quality and control are as good as the OEM idle once this is figured out. Self learning systems are great.

Idle control - I have nothing on the motor that is on/off, so no IAC. Idle control is RPM/temperature/pressure/TP based.

Throttle response - is excellent. I specifically designed it for maximum progressiveness on the throttle wheel. Again, it has an OEM responsiveness and feel.

Power loss - a purposefully designed system with tuned runners and injectors well separated from the throttle plates provides excellent VE.

My guess is that these "detractors" are based on systems from 20 years ago, under-developed electronic or simple mechanical ITBs, poor understanding of how they work and hence poor application, and based on power at an application not associated with any street use. I'm also inclined to believe ITBs are not used on OEM high performance cars for the reason of cost, packaging, and complexity, than performance or anything that fuel mapping can't overcome. Considering the nature of this project, the OEM intake was a no-go. I have not observed the "detractors" noted above, and have good reason to believe I've lost nothing with this set-up except for the occasional maintenance, set-up time, and under-hood clearance (not applicable), but it's not a daily driver either.

_________________
Terry
Cardomain photos

BlueOvalZ photo documentation
Image


Last edited by blueovalz on January 19, 2017, 12:25 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
PostPosted: January 19, 2017, 11:34 am 
Offline
User avatar

Joined: October 24, 2008, 2:13 pm
Posts: 3181
Location: Carlsbad, California, USA
I'd say you've done a pretty impressive job of coming up with a low cost solution. I love the "CanAm" look to the system too. I'd love to see a video with sound of your engine running.

Congratulations!

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


Top
 Profile  
Reply with quote  
PostPosted: January 19, 2017, 4:04 pm 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7379
Location: Massachusetts
I think the subject of modifying intake manifolds to make things we want is well worth exploring. I'd be happy with a single throttle, but I sure would like to see lower profile manifolds for our little cars. Especially for Ford 302...

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
Reply with quote  
PostPosted: January 20, 2017, 4:05 am 
Offline

Joined: November 11, 2013, 4:47 am
Posts: 617
Location: No. Nevada
Just sold my Edelbrock SBC Pro Flo FI setup.
Currently working on adapters for ITB's to varied Weber intakes.

To respond to a post above, BMW uses ITB's on some models.
in fact I may be using BMW ITB's for some of my conversions as they are simple to work out linkage for.

_________________
If I must be a one-man PC free zone, so be it!


Top
 Profile  
Reply with quote  
PostPosted: January 21, 2017, 3:50 pm 
Offline

Joined: July 6, 2009, 11:50 pm
Posts: 144
Bent Wrench wrote:
Too many detractors on ITBs.

If this was a good idea it would be found on most all production motors.



It certainly is in motorcycles. The throttle response on my ZX6R is incredible, and the power is very easily modulated. It's hard to argue with an engine producing over 200hp/L naturally aspirated.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY