modified fuel injection

dirtnap · Post by **dirtnap** » Thu Jun 17, 2004 3:15 am

I am presently building a motor for a local sprint car racer. It is a big bore(4.185)short stroke(3.270) 360 cu.It has 21 degree Alan Johnson heads presently it has an Isky cam 260/268 at .050,106, .645 lift I have 1.65/1.6 rockers .Although I am looking at another cam that is shorter duration with a tad more lift.The motor has 2 1/2 inch injection with 2 3/16 restrictors.I have a second set of injectors that we were toying with by moving the butterflies up .We have already made the modifications now we are making a new section to hold the butterflies we have raised them 1 inch now I want to make a plate to lower them too.What do think will be the advantages of either move?We have also made provisions for 2 different nozzle locations .

speedtalk · Post by **speedtalk** » Fri Jun 18, 2004 3:01 pm

Hey dirtnap, thanks for joining the board. I'll see if I can find someone to answer this question.

user-z68766209 · Post by **user-z68766209** » Mon Jun 21, 2004 10:01 am

What is the intake runner CC of those heads?
Brian B.

dirtnap · Post by **dirtnap** » Mon Jun 21, 2004 10:21 pm

Heads have 250cc runners 2.150 /1.550 supposedly flow around 328 at 700 lift

user-z68766209 · Post by **user-z68766209** » Wed Jun 23, 2004 4:18 pm

Man that is a lot of head for a 360ci.
Lots of RPM
Brian B.

SW · Post by SW » Wed Jun 23, 2004 5:05 pm

Are the restrictors mandated by where you race?What rpm range do you run the motor in?
shawn

dirtnap · Post by **dirtnap** » Thu Jun 24, 2004 1:16 am

2 3/16 restrictors required iron block 23 degree heads + or - 2 degrees .We have had to work this combination harder than our long stroke motors but it just seems to explode off the corner when the car is locked down.The heads do seem to like alot of fuel.The heads are supposed to flow 338 not 328 like i said before.If you havent seen them before the heads have oval intake ports and the transition from round butterfly to round valve is very smooth they have 54 cc chambers.

SW · Post by SW » Mon Jun 28, 2004 1:08 pm

Where do the restricters go in relation to everything else? Are they at the top of the injector, before the butterflies? Or after them? The best advice I ever got on restricter plate stuff came from a tv interview. One of the big Cup engine guys was talking about them and said "I wish they would give me a bunch of these things to stack up, but I only get one". After doing about a zillion hours of dyno work, I found out what he was talking about.

Shawn

dirtnap · Post by **dirtnap** » Tue Jun 29, 2004 1:25 am

The restrictors slide in the stacks above the butterflies have to be 3 inches long .Most people have been leaning toward bigger and bigger injectors even though they have to be restricted .Do you think it would be better to change the relationship between restrictor and butterfly than the butterfly and valve or injector location?

SW · Post by SW » Wed Jun 30, 2004 2:14 pm

I have never worked with a restricter like that, so I'm just going to guess on this. It would seem to me that you would want the butterfly as far away from the bottom of the restricter as you could get it. Reason is that I would want as long a period as i could get for that column of air to "expand" after it leaves the bottom of the restricter and the butterfly may affect or disturb that.Of course I thought I had a good idea of what to do with a standard plate restricter, too before we started, and boy was I wrong. lol.
Shawn