Slant Six Forum :: New Slant EFI intake....

I too, have read in books about the benefits of longer runners for low rpm torque. But I remember when Lou had his triple webers on one of his cars, and he raved about the throttle response it had with those short runners. It might have been the combination of short runners with the triple carbs. Hopefully Lou will chime in with his thoughts and experience!

Brian

Going to throw this out and I could be off base but one thing I hear a lot of is how when you have everything right 1 and 6 are lean 2 and 5 and good and 3 and 4 are rich. Wouldn't having the throttle body at the front of the engine cause as similar issue with the rear cylinders?

Quote:

I think this is more of an issue with a wet manifold system i.e. throttle body Injection or Carburetors.. With Port EFI that issue can / should be solved as I understand it.

Greg

Author:	CNC-Dude [ Sun Sep 08, 2013 5:07 pm ]
Post subject:	New Slant EFI intake....
Some of the East Coast racers already know from discussions that were had back in the winter at the Slant 6 Awards banquet with me about offering a new line of products for the Slant, more specifically an EFI intake manifold. So this weekend I finally got around to putting some dimensions together and got some 3D modeling done in Solidworks to get the ball rolling on this project. First, is the throttle bore placement that big of an issue for the slant guys. Many high HP EFI inline racers make sheetmetal intakes with their TB in a front mount location, while many OEM EFI engines like BMW and others opt for the side mount location. Maybe its fitment into the engine compartments or just outside the box thinking, but either location seems to have really good results either way, so maybe its just preference....what do you think? I plan to cast 2 different intakes, one for the mild street and race guys and then one for the all out racer with bigger TB capability and suitable also for blown apps.

Author:	Greg Ondayko [ Sun Sep 08, 2013 5:57 pm ]
Post subject:	Prototype EFI Slant 6 Street Manifold 9/8/13
Hello Folks, Scott, (CNC-Dude) and I are collaborating on a New EFI Log type Runner Manifold for the Slant 6. - It will be able to house a 65MM Throttle Body, Has radiused inside corners from the Log to the runners. - It will have Bosses for Throttle Body Mountings and for Linkages etc.. Not on these renderings. - It will have Provisions for the Triangle washers - Not on the rendering yet. Here are Some Renderings that Scott Has Come up with so far.. Feel Free to Share your thoughts on this - As all input is welcome - You will have a different viewpoint and thoughts on how best apply the design to your application. We will consider all suggestions and inquiries. Greg

Author:	Joshie225 [ Sun Sep 08, 2013 6:35 pm ]
Post subject:
The runners look really short. I had designed a manifold with two plenums to maximize acoustic tuning, but that requires two throttle bodies. Of course if the throttles come from a wrecking yard they are cheap and it's quite easy to get large enough ones. I should dig up the drawing and post a picture.

Author:	emsvitil [ Sun Sep 08, 2013 6:40 pm ]
Post subject:
Thoughts: longer runners (could fold over itself for if needed) TB on rear end Plenum perpendicular to head

Author:	Sam Powell [ Sun Sep 08, 2013 6:51 pm ]
Post subject:
The slant is a long engine with limited front space. There is more room on the side. Ed's design has potential to save space. Short runners are for high rpm. Long runners are for low rpm torque. This according to Brit literature, folks who know a thing or two about inline engines. Sam

Slant Six Forum https://slantsix.org/forum/

New Slant EFI intake.... https://slantsix.org/forum/viewtopic.php?t=53276	Page 1 of 11

Author:	CNC-Dude [ Sun Sep 08, 2013 7:09 pm ]
Post subject:
In the current drawing, the runners are 6" long, and the plenum is 4" square, so it will stick out from the head 10", plus the width of the TB and filter/airbox setup. I also think that once I began putting some dimension to this part that the plenum needs to be a little longer because the rear runner is shrouded against the rear plenum wall. As I mentioned, a side mount location is doable with no problem, and there have been many successful manifolds done for racing in this configuration as well as at the front. But given the engine is slanted, there is a ton of room on the side to do this, and may be the best spot for one on the Slant.

Author:	bmimken [ Sun Sep 08, 2013 7:37 pm ]
Post subject:
The street guys might wish for it to allow room for A/C compressors in the front. Might be better to have the TB opening on the side? I too, have read in books about the benefits of longer runners for low rpm torque. But I remember when Lou had his triple webers on one of his cars, and he raved about the throttle response it had with those short runners. It might have been the combination of short runners with the triple carbs. Hopefully Lou will chime in with his thoughts and experience! Brian P.S.- What are the plans for the runners' inside dimensions? Similar to the Offy runners, or more similar to the Clifford runners? I believe there is a difference between the two, although I do not know the details. Maybe I am wrong.

Author:	CNC-Dude [ Sun Sep 08, 2013 8:03 pm ]
Post subject:
I had planned to keep the runner size toward the small side on the street version, since air velocity is going to be of concern to those looking to have good street manners in such a setup. But again, its just a prototype and subject to change once a few get cast and tried out to see if theory and "real world" elements clash or are in sync with each other.

Author:	ceej [ Sun Sep 08, 2013 8:09 pm ]
Post subject:
Sounds like the right path forward! I'd like to see one set up for GMC blown applications. But I'm standing amongst a field of very few. At present count, three. That's OK, I massacred a Hyperpak last month. It should do the trick! CJ

Author:	Tom Drake [ Sun Sep 08, 2013 8:15 pm ]
Post subject:
Put two sets of bungs in it? The more distance between the injector and valve you give the better the atomization you will get. With an end inlet taper the diameter of the plenum to keep up velocity towards the rear cylinders. Change it to center inlet for better distribution. Could even put in deflectors to channel airflow.

Author:	CNC-Dude [ Sun Sep 08, 2013 9:06 pm ]
Post subject:
I like that design Tom, how long are the runners. Also, is the plenum flat on the bottom just as on top. Also, in my second drawing that shows a look into the plenum thru the TB, you can see that the #3 & 4 runners cant have as big of a radius at the port entry as the other ports, so I was thinking to actually move them farther apart at the plenum end so a more equal sized radius could be placed on all of them at this end.

Author:	emsvitil [ Sun Sep 08, 2013 11:20 pm ]
Post subject:
Quote: I too, have read in books about the benefits of longer runners for low rpm torque. But I remember when Lou had his triple webers on one of his cars, and he raved about the throttle response it had with those short runners. It might have been the combination of short runners with the triple carbs. Hopefully Lou will chime in with his thoughts and experience! Brian I assume you're talking about dual-bodied webers, so you have a carb body per cylinder....... Anyway when you have a carb per cylinder, the intake runner length acts as if it's the short runner from head to carb PLUS the length of the carb PLUS the velocity stack............

Author:	jhdeval [ Mon Sep 09, 2013 4:17 am ]
Post subject:
Going to throw this out and I could be off base but one thing I hear a lot of is how when you have everything right 1 and 6 are lean 2 and 5 and good and 3 and 4 are rich. Wouldn't having the throttle body at the front of the engine cause as similar issue with the rear cylinders? I am not sure how to fix it but I have an idea. What if the first 3 and last 3 were grouped together and fed by say a 40mm entry passage and then from the passenger side of the motor fed from the larger throttle body that split the intake air to both the front and back half. I think this could potentially shorten the runners and provide more air at the same time. I am not a designer just shooting from the hip.

Author:	Greg Ondayko [ Mon Sep 09, 2013 7:12 am ]
Post subject:
Quote: Going to throw this out and I could be off base but one thing I hear a lot of is how when you have everything right 1 and 6 are lean 2 and 5 and good and 3 and 4 are rich. Wouldn't having the throttle body at the front of the engine cause as similar issue with the rear cylinders? I think this is more of an issue with a wet manifold system i.e. throttle body Injection or Carburetors.. With Port EFI that issue can / should be solved as I understand it. Greg

Page 1 of 11	All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/

Author:	jhdeval [ Mon Sep 09, 2013 7:36 am ]
Post subject:
Quote: Quote: Going to throw this out and I could be off base but one thing I hear a lot of is how when you have everything right 1 and 6 are lean 2 and 5 and good and 3 and 4 are rich. Wouldn't having the throttle body at the front of the engine cause as similar issue with the rear cylinders? I think this is more of an issue with a wet manifold system i.e. throttle body Injection or Carburetors.. With Port EFI that issue can / should be solved as I understand it. Greg My main concern was more of if the air comes in from the front how much of that is moved to the back of the intake. It may be a moot point. Let me give an example if you bring in 60 cfm is each cylinder going to only take 10cfm or will they take what they can and leave the rest starving. On the flip side of this can there be to much air? How would it be dealt with if that does happen. Again I may just be waxing on but the main point of an intake is to provide air.