Fuel Injection Options and Advice Options

[bkrantz]

Decision time soon (preferably only once). Later this month I will pick up my refurbished case, crank, and heads from Competition Engineering in Phoenix. I want to build this up to 2056 and use fuel injection.

So, do I keep the stock D-jet that was on the car? I have no idea if it works. And I expect that I will spend time and money tracking down rebuilt/replacement components. Plus modify the system for the increased displacement.

Or do I go aftermarket, spend more time and money, but hope for better results? And maybe some sexy twin intakes?

[Gint]

I’m planning aftermarket FI my 2056. And I thought I wanted ITBs, but I don’t want to have to sync anything. That's one of my reasons to convert from carbs to FI.

So here’s a question... Is there any reason to think the stock djet runners, plenum, throttle body won’t flow enough air for a 2056?

Discuss - I’m riding down the highway through Planet Utah.

[JamesM]

So here’s a question... Is there any reason to think the stock djet runners, plenum, throttle body won’t flow enough air for a 2056?

I think you would need a pretty extreme 2056 before it becomes an issue to consider. I dont recall the exact figures but i did the math on it before and I think it doesn't become an issue until you start getting above ~140HP at which point you also need to be thinking about exhaust (headers) as well.

Mine is a bit of a screamer (spins to 7k) and im running it through a modified 1.8 l-jet Plenum with 50mm Vanagon TB. I suspect where you are at the stock 2.0 plenum and runners would be preferred from a drivability standpoint as it gives a better vacuum signal, and in theory probably better midrange torque.

[Mark Henry]

So here’s a question... Is there any reason to think the stock djet runners, plenum, throttle body won’t flow enough air for a 2056?

I think you would need a pretty extreme 2056 before it becomes an issue to consider. I dont recall the exact figures but i did the math on it before and I think it doesn't become an issue until you start getting above ~140HP at which point you also need to be thinking about exhaust (headers) as well.

Mine is a bit of a screamer (spins to 7k) and im running it through a modified 1.8 l-jet Plenum with 50mm Vanagon TB. I suspect where you are at the stock 2.0 plenum and runners would be preferred from a drivability standpoint as it gives a better vacuum signal, and in theory probably better midrange torque.

(IMG:style_emoticons/default/smile.gif)

With Djet intake and SSI's there's no way in hell you can get 140hp, at least not without fudging the dyno numbers, even 130 would be a stretch. That said the stock d-jet intake and SSI's will work fine for a 2056.

Spins to 7K? Is this a full race engine? What are you doing about valve float? What cam?

[JamesM]

(IMG:style_emoticons/default/smile.gif)

With Djet intake and SSI's there's no way in hell you can get 140hp, at least not without fudging the dyno numbers, even 130 would be a stretch. That said the stock d-jet intake and SSI's will work fine for a 2056.

Spins to 7K? Is this a full race engine? What are you doing about valve float? What cam?

Thats what i am saying, you will run out of exhaust before you run out of intake with the stock plumbing.

As for my motor, its used in my dedicated autocross car but I have no idea exactly what is in it as I bought it as a fresh long block from Bruce Stone. It was a motor his son had European Motor Werks build but he changed directions on his project before ever installing it. I was looking to build a new motor for my autocross car at the time it came up for sale at a price to good to pass on. Im pretty sure the cam is one of EMWs but no idea which one. Things i do know about it from external observation, It has reworked AMC heads, some pretty massive stainless valves, dual valve springs, solid rocker spacers, 911 adjusters, and the flywheel was seriously lightened. They told me EMW had also done some custom combustion chamber work but that I cant confirm as I have never pulled the heads. It comes on cam noticeably around 3800rpm, and pings pretty bad with anything less than 91 octane even at my 4500ft elevation. and yes its running the 4-1 Eurorace headers

Was told it has AA pistons in it so yea... i don't normally run it up to 7k out of an abundance of caution, but it does get there without much fuss. When i was initially tuning the fuel map I pretty much just let the motor run to where it wanted to run to and found power didn't start dropping until after ~6500 rpm, I was a little shocked when i checked the logs after and found I was hitting 7k+. since tuning it I usually run it with a limiter set at 6500 (depending on the course) that I am pretty frequently bouncing off of when autocrossing. Not sure how i didn't blow those AA pistons (if thats what they actually are) to pieces, perhaps they are better than people tend to imply?

Honestly this motor feels more aggressive to me over 5k than my buddies Rabby cam'd 2270 with ITBs that i tuned MS on. Havent had it on a dyno yet but one of the local shops that does air cooled cars recently got one, so I hope to get over there come spring to see what she has left in her after 4 seasons of abuse. I can say that with my setup I am seeing slight increasing manifold vacuum at the top end while WOT so I suspect I am starting to run up on the limit of what the intake can handle.

Ill have to see if I still have the datalogs on those 7k pulls, they were a beautiful thing.