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Single Plane MPFI throttle body question

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Old 07-21-2009, 03:46 PM   #1
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Single Plane MPFI throttle body question

I have a single plane victor jr MPFI on my 383 11:1 compression 195cc AFR headed engine with a healthy camshaft (intake 230* + and exhaust 240*+). I'm trying to decide on a throttle body. I'm looking at Accel and I see they have a 1200 cfm and 1550 cfm ratings. Which one would be the best fit for me with a 2" spacer on top of the intake?

Its used as a weekend driver and see some track time.
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Old 07-21-2009, 11:11 PM   #2
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Re: Single Plane MPFI throttle body question

Well...I'm going with the 1550....we shall see how it does.
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Old 07-23-2009, 08:17 AM   #3
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Re: Single Plane MPFI throttle body question

I'm running a MiniRam on my 406 but am very intrigued with the single plane intake. Are you converting from HSR?

The 1550 cfm throttle body is really healthy. Hopefully it doesn't kill your low rpm response. Make sure you post when you get it on the road.

BTW - What are you using for ecm?
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Old 07-24-2009, 03:12 AM   #4
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Re: Single Plane MPFI throttle body question

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Originally Posted by HiTech5 View Post
I'm running a MiniRam on my 406 but am very intrigued with the single plane intake. Are you converting from HSR?

The 1550 cfm throttle body is really healthy. Hopefully it doesn't kill your low rpm response. Make sure you post when you get it on the road.

BTW - What are you using for ecm?
I'm using the 7730 ecm.

1550 cfm throttle body is healthy but we shall see. I'm hoping the combinatino will like the extra air in the engine.

Yes, I converted to single plane from HSR.
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Old 07-24-2009, 08:25 AM   #5
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Re: Single Plane MPFI throttle body question

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I'm using the 7730 ecm.
How is that working with the big cam?

I imagine you have it ground on 112* ?

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Old 07-24-2009, 11:28 AM   #6
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Re: Single Plane MPFI throttle body question

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How is that working with the big cam?

I imagine you have it ground on 112* ?

-- Joe
Yes...its ground on a 112 lsa.

Lift is around the .550 area....I want to put 1.6 rockers on it to increase the lift a little bit but need to check PTV clearance first and put my new headers on it....upgraded from my 1 5/8" LTs with only a 1 1/4" flange opening (the AFR port is 1 9/16" wide so I'm about to gain some cfm through the new headers....new headers are 1 7/16" wide at the exhaust port.
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Old 07-24-2009, 12:59 PM   #7
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Re: Single Plane MPFI throttle body question

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Yes...its ground on a 112 lsa.

Lift is around the .550 area....I want to put 1.6 rockers on it to increase the lift a little bit but need to check PTV clearance first and put my new headers on it....upgraded from my 1 5/8" LTs with only a 1 1/4" flange opening (the AFR port is 1 9/16" wide so I'm about to gain some cfm through the new headers....new headers are 1 7/16" wide at the exhaust port.
Sounds good!

I'm running a 106/106 cam so. A '730 won't run that

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Old 07-25-2009, 10:25 AM   #8
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Re: Single Plane MPFI throttle body question

What headers are you using?
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Old 07-25-2009, 10:55 AM   #9
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Re: Single Plane MPFI throttle body question

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What headers are you using?
This is a truck so.....

I had Hedman and now I have a brand that I forgot the name but it was a set for a 1967-1969 Camaro that I got to work on the truck. Ceramic coated, etc.
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Old 07-25-2009, 11:01 AM   #10
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Re: Single Plane MPFI throttle body question

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Sounds good!

I'm running a 106/106 cam so. A '730 won't run that

-- Joe
Don't know how much to expect from the headers with the new opening but I know they are going to flow more.

Nice LSA for sure on your camshaft.

I'm thinking about switching to the 411 setup or to a 7427 ecm with the MPFI so I can run a 4L60e or 4L80e transmission.
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Old 07-25-2009, 04:56 PM   #11
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Re: Single Plane MPFI throttle body question

Quote:
Originally Posted by YenkoST View Post
Don't know how much to expect from the headers with the new opening but I know they are going to flow more.

Nice LSA for sure on your camshaft.

I'm thinking about switching to the 411 setup or to a 7427 ecm with the MPFI so I can run a 4L60e or 4L80e transmission.
That the vortec truck ECM?

I like the idea of the vortec/ls1 MAF. You can get away with a lot more camshaft by reading airflow directly, rather than vac. Or lack of. I tried a really big cam (like 80 degrees of overlap) and the thing idled within like 20kpa or WOT. Not much tuning resolution.

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Old 07-25-2009, 05:42 PM   #12
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Re: Single Plane MPFI throttle body question

Why cant you just run open loop? you can get some pretty nasty cams to run ok on 730 in open loop

FWIW, i got a single plane EFI setup now but i'm using an elbow with LS1 throttlebody instead of the carb style MPFI setups. I would think 1200 cfm would feed that motor but 1550 cant hurt too much with a high compression 383. Just gotta play with the tune to allow such large changes in fueling with mild throttle inputs, since slight change in TPS position will mean much larger amount of air going thru the motor than a stocker TPI 52-58 mm unit which only flows 900cfm or so
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Old 07-25-2009, 11:07 PM   #13
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Re: Single Plane MPFI throttle body question

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Originally Posted by Orr89RocZ View Post
Why cant you just run open loop? you can get some pretty nasty cams to run ok on 730 in open loop
That has nothing to do with it. Running open loop is a given on a moderate cam. But on a big cam, your idling way on the end of the map spectrum. You have hardly any vac, so you have no tuning ability. Remember, VE fueling is based on MAP. If you only are working in two columns you can't really tune the entire operating range.

Quote:
Originally Posted by Orr89RocZ View Post
FWIW, i got a single plane EFI setup now but i'm using an elbow with LS1 throttlebody instead of the carb style MPFI setups. I would think 1200 cfm would feed that motor but 1550 cant hurt too much with a high compression 383. Just gotta play with the tune to allow such large changes in fueling with mild throttle inputs, since slight change in TPS position will mean much larger amount of air going thru the motor than a stocker TPI 52-58 mm unit which only flows 900cfm or so
I've never run into a situation where the throttle body was too big, but I've never tried anything larger than like an 80MM monoblade, or twin 58.

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Old 07-26-2009, 02:33 AM   #14
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Re: Single Plane MPFI throttle body question

Dont they have an updated bin/xdf file that offers alot more resolution based across a broader rpm range for the 730? I dont follow to much on the speed density stuff since I was MAF, but i've read the posts about big cams at idle and seems like even the big cams for street/strip cars dont idle too much over 70KPA...if your too much over that then is it really street car? Its just weird to me because 87TA on this board has a solid roller on his 406 that does go high 10's and its running fine on the 730... his total overlap was as much as my cam in my 383 which did have alot of overlap. He may have had more i dont remember

I aggree resolution disappears but cant you just use PE mode to help fine tune fuel where its needed, if you dont have the adjustability in the VE tables due to high KPA idle values?
How did your CC306 cam idle in that 350? (Think that was you who had that setup) To me thats about as big of a cam you'd want in a street motor so if you need to go larger than that then somethings wrong
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Old 07-26-2009, 09:52 AM   #15
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Re: Single Plane MPFI throttle body question

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Originally Posted by Orr89RocZ View Post
Dont they have an updated bin/xdf file that offers alot more resolution based across a broader rpm range for the 730?
Yes, but RPM doesn't matter. VE does. The '730 calculates fuel based on MAP. So let's talk numbers.

Say on a smallish performance cam, something in the 220* range on 112lsa, you may idle at around 55-60kpa. Cruise might be in the 40s, and WOT in the high 90s. This is ideal for MAP because you have a broad range that can be tuned in. This is not taking WOT into account.

Now lets switch to a big solid cam, something with 250* at .050", on 106lsa.
You might idle at 95kpa, cruise might be 85-90kpa. WOT high 90s, 100kpa.
You have almost no range to tune. All you can really do tune in 2-3 columns,
and increase VE with RPM. But that is not reliable either. (see attached)


Quote:
Originally Posted by Orr89RocZ View Post
I dont follow to much on the speed density stuff since I was MAF, but i've read the posts about big cams at idle and seems like even the big cams for street/strip cars dont idle too much over 70KPA...
A "big" cam to these guys is 236* on 112 lsa.

Quote:
Originally Posted by Orr89RocZ View Post
if your too much over that then is it really street car?
Yes. Building a 5k engine and throwing a little cam at it is a waste of money and potential. I've always gone by the notion of putting a smallish cam in a motor, and making power with boost. But to make crazy power naturally aspirated, you need more cam. A 400 for example, with a large solid cam on 106 degrees makes over 500 foot lbs of torque at 2000rpm.. That is a street car.

Quote:
Originally Posted by Orr89RocZ View Post
Its just weird to me because 87TA on this board has a solid roller on his 406 that does go high 10's and its running fine on the 730... his total overlap was as much as my cam in my 383 which did have alot of overlap. He may have had more i dont remember
What is his cam specs? I'd be curious to see datalog of his car running.

Quote:
Originally Posted by Orr89RocZ View Post
I aggree resolution disappears but cant you just use PE mode to help fine tune fuel where its needed, if you dont have the adjustability in the VE tables due to high KPA idle values?
Yep, but PE is wot. What do you do about part throttle cruise, decel, etc.

Quote:
Originally Posted by Orr89RocZ View Post
How did your CC306 cam idle in that 350? (Think that was you who had that setup) To me thats about as big of a cam you'd want in a street motor so if you need to go larger than that then somethings wrong
Like crap. 80kpa idle. Part throttle surges.

Lot of guys running CC306 is on LT1s, which are like what 10.8:1 compression. I ran it on a 10:1 motor. More compression, or more cubes will tame a cam.

And, a lot of LT1 guys run MAF - which makes tuning easier.

The problem with MAF on a thirdgen is you have a limit to reading airflow. The concept is better for a big cam, since you know at idle and part throttle a large cam passes hardly any air. So your midrange will be spot on. But at WOT, you will most likely peg the sensor by 4,000rpm.

-- Joe
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Last edited by anesthes; 07-26-2009 at 09:56 AM.
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Old 07-26-2009, 12:00 PM   #16
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Re: Single Plane MPFI throttle body question

Yeah what i ment was I thought they had a updated bin/xdf that not only had more rpm to work with but also had a broader MAP scale. I guess not which is disappointing. I can see that being a problem with a larger cam.

My MAF did well at idle and part throttle but yes, it did max out the sensor by 4000-4500 rpm I do believe.

87TA's cam i dont think was huge for a solid roller. I think its a TPIS grind... 242/242 on a 112 with .572 lift each lobe. 278 advertised so its overlap wasnt as much as my cam. I think he had another setup tho that did have some overlap to it and he got it to idle/drive well, but I'm not sure how much kpa at idle it had.
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Old 07-26-2009, 12:10 PM   #17
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Re: Single Plane MPFI throttle body question

Quote:
Originally Posted by Orr89RocZ View Post
Yeah what i ment was I thought they had a updated bin/xdf that not only had more rpm to work with but also had a broader MAP scale. I guess not which is disappointing. I can see that being a problem with a larger cam.
Yep. No matter what changes you do to the bin, you can't escape the fact that the VAC range is limited due to the camshaft.

I really like MAP you know. For most of my combos it has been great, especially forced induction. I have a lot of respect for the Vortec and LSx MAF setups as well, because I think you can do more with them as they directly measure airflow.

Quote:
Originally Posted by Orr89RocZ View Post
My MAF did well at idle and part throttle but yes, it did max out the sensor by 4000-4500 rpm I do believe.

87TA's cam i dont think was huge for a solid roller. I think its a TPIS grind... 242/242 on a 112 with .572 lift each lobe. 278 advertised so its overlap wasnt as much as my cam. I think he had another setup tho that did have some overlap to it and he got it to idle/drive well, but I'm not sure how much kpa at idle it had.

He has a carbed track car too, doesn't he? I thought I remember looking his specs up a few years ago, and one car was EFI and the other carb.

That TPIS grind is going to be fairly computer friendly, probably similar to a cc306 but with more lift and faster ramps. (i.e, superior to) but fairly similar in regards to tuning.



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Old 07-26-2009, 01:36 PM   #18
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Re: Single Plane MPFI throttle body question

Yeah for some reason i thought it was abit more aggressive than that but that motor makes serious power. My 383 needed a 150 shot just to hang with his motor's all motor performance and my motor was no slouch. Yet his was just as streetable as mine was.

He does have a carbed track car,now a vega instead of a 82 camaro. Other car is miniram'd running 730 ecm.

I didnt mean to get off topic with this. As far as throttle body size goes, you really cant go too big on the air flow side because you want to see 100KPA or so at WOT. Anything less is a slight restriction. 1550 cfm should do ok in that regard and i dont think it will hurt throttle response too much due to the cubes and compression of that motor
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Old 07-27-2009, 03:19 PM   #19
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Re: Single Plane MPFI throttle body question

Quote:
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That the vortec truck ECM?

I like the idea of the vortec/ls1 MAF. You can get away with a lot more camshaft by reading airflow directly, rather than vac. Or lack of. I tried a really big cam (like 80 degrees of overlap) and the thing idled within like 20kpa or WOT. Not much tuning resolution.

-- Joe
Yes...the 411 is the Vortec PCM. But I will probably run SD with it as well do to the open filter I'm running. If I go turbo or S/C then I can see myself with a Lingenfelter 100mm MAF.

I love my SD setup but I really don't like changing the governor on teh 700r4 and esp. making 10 spring adjustments to get it to shift perfect when I can do it from a push of a button.

The Camshaft I'm running is the GM847 just the Crane version (which is the same as the GM unit).

I found a dyno of them test a 1000, 1200, 1500, and 2000 cfm throttle body on a 406 EFI engine....each throttle body needed more fuel but from 1000 cfm to 2000 cfm....there was a 20hp gain I believe and they also increased torque from the starting rpm of the pull which was 2500rpm I believe.

I didn't want to go with teh 2000 but I figured the 1500 would give me room to grow and I have enough injector...I'm running 38 lbs.
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Old 07-29-2009, 08:22 PM   #20
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Re: Single Plane MPFI throttle body question

Orr-

How would you compare the single plane to the HSR? I'm really thinking of converting. What size TB are you using?
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Old 07-29-2009, 09:51 PM   #21
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Re: Single Plane MPFI throttle body question

Well i had the HSR with a mild port job and a Holley twin 58mm throttlebody. I now have a Victor E EFI manifold that is supposively good to 8500 rpm and i'm running stock LS1 75-76mm throttle body. I have a custom made 90 degree intakeelbows.com intake elbow. It sits very high but thats the way I spec'd it out. I thought i needed 3" rise from manifold flange to bottom of throttlebody flange but really only needed about 2 to clear the waterneck. I also made it extend outward about 9 inches to make the throttle body sit around where the HSR TB was..if not a touch further out.

It stands taller than the HSR this way but would be closer to the same size if elbow was 2" rise instead of my 3". I got a 4 inch cowl hood now and it clears the elbow by about .75 to 1". I cant remember exactly how much clearance i had but definately too tall for stock hoods or even mild cowls. 3" may clear, but 4" definately works and leaves room to spare.

If you run a TB like Yenko is doing, the one that looks like a carb sorta, then you wont have to worry too much about height issue.

FWIW, LS1 guys have been seeing good gains with MPFI style TB's over intake elbows, but it depends on the design of the intake elbow. Some tight radius elbows are restrictive while others flow much more. But some guys have seen over 50-60whp in just an throttle body swap from some 90 degree type elbows

Compared to the HSR, i think the HSR and single plane would be similar to 4500-5000 rpm and there the single plane will act more like a miniram and take it on the top end. Runners are big and do flow good but my manifold needed ported to 1205 gasket. It was much smaller out the box so thats not good Match to your heads and it will work nicely.

Anesthes has tried alot of the manifolds out there. He's sticking with single planes. They are good intakes as they are proven on carb race applications, they will do good on EFI street strip motors for sure. The reason i converted was I wanted to be sure that air distribution was as even as possible and single planes seem to do a better job of that when compared to front throttle body type intakes like miniram/lt1/HSR. I had a clear problem with air distribution on my HSR motor, back cylinders were richer for some reason. Number 7 was the richest. My turbo application needs even air flow and from most guys i talked to about their single plane setups, they see fairly close distribution across all cylinders
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Old 07-31-2009, 10:39 PM   #22
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Re: Single Plane MPFI throttle body question

To elborate a little bit more on Orr...I actually had the engine up and running with a 1000 cfm throttle body once but had issue with the throttle body and sent it back.

The Single plane off idle throttle response is 10x better it seems like with the 2" spacer I'm using even with the bigger cam. Idle is much chirsper and hte A/F ratio according to my wideband doesn't jump around as much....I believe the HSR has a condition that doesn't force the same equal air into #7/#8 as the rest of the cylinders....those cylinders were always richer on the spark plugs than the rest N/A. However, FI I feel would be the opposite....1 and 2 would be richer as air would go past them in a forceful manner.
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Old 08-12-2009, 03:41 PM   #23
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Re: Single Plane MPFI throttle body question

Yenko - Get the 1550 on yet?

I bought a Victor EFI manifold today. I'm torn between the 1350 TB 1550 TB.
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Old 08-12-2009, 07:06 PM   #24
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Re: Single Plane MPFI throttle body question

I also saw the rich 7/8 cylinders. I would think that would be due to a part throttle/idle condition since airspeed is slower across the plenum. Rears dont get as much so its richer. WOT would probly show slightly rich fronts because of the opposite, but its hard to say. Things may even out at WOT or it still may be slightly rich on the rear
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Old 08-12-2009, 09:19 PM   #25
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Re: Single Plane MPFI throttle body question

I wouldnt worry about being off-topic...lots of great information in this thread.
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Old 08-20-2009, 05:57 PM   #26
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Re: Single Plane MPFI throttle body question

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Yenko - Get the 1550 on yet?

I bought a Victor EFI manifold today. I'm torn between the 1350 TB 1550 TB.
Yep...I have it but haven't got it running yet...I'm trying to finish buttoning up the exhaust which should be this weekend and then we shall see where it goes.

Still looking for the right throttle stud for the throttle body. I got the correct TV cable stud though. Also need a throttle closed spring just to help with the pedal feel a little bit firmer.

Here is a good read though.

http://www.carcraft.com/techarticles...ech/index.html
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Old 08-21-2009, 11:23 AM   #27
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Re: Single Plane MPFI throttle body question

That 1550 is giving me a Woody!

My one concern is part throttle acceleration and idle quality so Yenko, hurry up and get your car going.
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Old 08-21-2009, 02:15 PM   #28
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Re: Single Plane MPFI throttle body question

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That 1550 is giving me a Woody!

My one concern is part throttle acceleration and idle quality so Yenko, hurry up and get your car going.
I'm working on it...I think it will be fine...I got the IAC and TPS wiring diagram so I'm making up the adapters as we speak and then finish up the exhaust...mount the throttle body and see what happens.

The only thing I have to work on is making an air foil or something for the 2 bolt air cleaner bolt to a 1 stud for my air cleaner. I was think of just putting a plate across and connecting but and air foil sounds a lot better.
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Old 09-03-2009, 11:14 PM   #29
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Re: Single Plane MPFI throttle body question

Well...its official....the engine is running....got it running without the IAC. Tomorrow I begin the procedure to get the IAC working. The IAC seems like it wasn't extending all the way but I'll work on it more tomorrow.
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Old 09-04-2009, 05:22 AM   #30
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Re: Single Plane MPFI throttle body question

Thats a lot of air. I assume by looking at it that both of the throttle blades open at once? Have you had a chance to drive it yet? Curious to see how something like that is on the road.
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Old 09-04-2009, 05:35 AM   #31
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Re: Single Plane MPFI throttle body question

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Originally Posted by anesthes View Post


And, a lot of LT1 guys run MAF - which makes tuning easier.
I can attest to that. With the MAF, theres no tuning needed. The PCM was already calibrated for the MAF, so the tuning was mainly confined to disabling closed loop, setting up the AFRs, and dialing in the SA. The MAF itself holds the AFRs within +/- 2% of whats desired even though its set for full open loop.
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Old 09-04-2009, 03:54 PM   #32
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Re: Single Plane MPFI throttle body question

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Thats a lot of air. I assume by looking at it that both of the throttle blades open at once? Have you had a chance to drive it yet? Curious to see how something like that is on the road.
No...just got it running last night...its not a double action throttle opening system...its a progressive link...one opens up about 30% throttle then the 2nd one kicks in. Hope to drive it in the morning if I can get it running tonight with the IAC....having a little bit of a problem with it but still working out the bugs.
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Old 09-05-2009, 04:33 AM   #33
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Re: Single Plane MPFI throttle body question

Oh, ok. So it is progressive. Im using a 1000 CFM edelbrock TB, mainly because its one of the only ones that has the late model high-res IAC used by the SFI PCMs.

I dont know how the 7730 handles the IAC, but on some of the computers, they can give you fits when you replace the IAC as the desired and actual pintle positions are not the same until the ECM resets the IAC. If you haven't tried it yet, you might want to leave the IAC plugged in for a full start-up, run, and shut-down cycle so it can be reset to the correct park position.
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Old 09-05-2009, 01:04 PM   #34
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Re: Single Plane MPFI throttle body question

I haven't tired yet.....just been running on min. air setting....the IAC at first start did rev to like 2500 rpms and stayed there. Even when I grounded the IAC...it didn't extend all the way to close the hole. So, I'm wondering if I need to set it to the proper length and then start it up that way. I heard the IAC growling so I know it was extending or should have been extending.
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Old 09-06-2009, 03:21 AM   #35
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Re: Single Plane MPFI throttle body question

That almost sounds like there is something wrong with the IAC itself if the stepper energizes but doesnt move the pintle. Do you have a spare one you could try (assuming the pintle size is standard)? From teh pic it looks like it uses a standard aftermarket IAC. Could also try moving it by hand. Some of the aftermarket IACs such as the one made by BWD have pintles that can easily be moved/removed.
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Old 09-06-2009, 01:18 PM   #36
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Re: Single Plane MPFI throttle body question

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That almost sounds like there is something wrong with the IAC itself if the stepper energizes but doesnt move the pintle. Do you have a spare one you could try (assuming the pintle size is standard)? From teh pic it looks like it uses a standard aftermarket IAC. Could also try moving it by hand. Some of the aftermarket IACs such as the one made by BWD have pintles that can easily be moved/removed.
I did move it by hand to close it up so we shall see. I don't have a spare one but it looks like the IAC style being used on the LT1 or 96-up trucks. But, I'm going to hook it back up and ground it so I can set my min. air settings and disconnect the computer timing line. So, hopefully I can get that done and get the IAC to working....if not....I'll probably go and retrieve an LT1 unit from a 94 year Camaro.

I had to work on a custom return spring, etc for it yesterday.
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Old 09-07-2009, 03:01 AM   #37
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Re: Single Plane MPFI throttle body question

If its a 96+ IAC with the flat straight 4-pin connecter (a pic will tell for sure), then there may be some issues with running it. The new delphi IACs have half the step size of the old IACs. To sweep the IAC from fully open to fully closed takes close to 400 steps vs the 160 for the old IACs. The problem is that the ECMs can only register from 0-255 IAC steps. This leads to the potential issues of the IAC not working properly because the computer may not be able to sweep the IAC over its full range, depending on how the idle control logic works. I would suspect that most of the older idle control routines may have issues trying to operate that IAC.
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Old 09-07-2009, 01:53 PM   #38
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Re: Single Plane MPFI throttle body question

I have that problem. LS1 IAC with LS1 TB with 730 ecm using code 59. IAC doesnt function right because its sweep range is more than older ecm's. Probly could correct that in the tune for 730/8D and 165/6E type setups but i dont see a table to adjust the range of the IAC in code 59
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Old 09-12-2009, 03:14 PM   #39
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Re: Single Plane MPFI throttle body question

Just an update....the IAC wiring from Accel is incorrect for the IAC...when you ground the IAC it opens up....not closed so with teh help of zz17iroc who has the 1200cfm Accel throttle body....he suggest another wiring diagram so I'm going to try that way.
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Old 09-12-2009, 08:58 PM   #40
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Re: Single Plane MPFI throttle body question

Its alive and on the streets. Tuning is going ok...VE needs some adjustments from the HSR and 32 lb/hr injectors.

Its much more fun than the HSR system I had. The gain of low end power with the bigger cam that was added is very nice!
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Old 09-15-2009, 09:07 PM   #41
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Re: Single Plane MPFI throttle body question

Little bit more info. The 1550 cfm throttle body definately needs a return springs to help it close fully at idle. Other than that, the 1550 is very sensitive. Light throttle transitions need a little tweaking but heavy throttle transitions need even more. So far, the TPS gain in the tune looks linear with heavy increases in the 18% up area but that could be a part of my combination as well.
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Old 09-18-2009, 03:05 AM   #42
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Re: Single Plane MPFI throttle body question

So the IAC is working OK, I assume?

I would expect that to need a lot of momentary TPS AE on tip in, due to the sudden transients that you will have when slamming the throttle open. Its also not very linear with change in TPS, as you not only have the throttle opening, but the secondary plate opening up after 30% or so.

Have you actually tried a full throttle slam with that thing yet? Even with just a 1000 CFM, I found that to be the hardest thing to tune for. Even with a PCM that calculates the fueling in real time there is enough lag in the MAP when its in SD mode to cause it to bang out the intake if it doesnt have AE.

Another thing that Ive found out with my vic jr is that since the injectors point straight down, it needs a good deal of MAP AE as well when the engine is cold. The fuel basically hits the floor of the intake and stays there.

Also, just out of curiosity, how much overlap does your cam have? Ive found that with a decent ammount of overlap, once the throttle opens, the exhaust pulses will pull a good deal of the fuel out into the headers. That makes the engine appear to run lean at low speeds. Im still playing with the injector timing to find the right time to fire each injector. Has to be delayed enough that the cam wont steal the fuel, but not so much that the intake valve closes before the injector finishes firing.

Last edited by dimented24x7; 09-18-2009 at 03:12 AM.
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Old 09-18-2009, 05:43 PM   #43
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Re: Single Plane MPFI throttle body question

The IAC is working....not as strong as the TPI IAC worked but its working. I need some more cold start up fuel as its a little bit lean. I haven't done any WOT pulls yet but at low speeds I'm seeing a rich condition according to my wideband. However, up top, it seems to lean itself out and runs a nice 14:1 during acceleration.
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Old 09-27-2009, 10:42 PM   #44
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Re: Single Plane MPFI throttle body question

Figured y'all would like to see some pics.





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Old 09-27-2009, 10:53 PM   #45
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Re: Single Plane MPFI throttle body question

What kind of hood do you have? Will this set-up clear a stock hood?
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Old 09-28-2009, 09:31 PM   #46
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Re: Single Plane MPFI throttle body question

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What kind of hood do you have? Will this set-up clear a stock hood?
This is in a C1500 truck....not a Camaro. I only have about 3/4" to clear this when my Stealthram had about 3" to clear...so...I don't think this would fit a stock camaro hood.
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Old 09-29-2009, 12:38 PM   #47
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Re: Single Plane MPFI throttle body question

FWIW - I'm in the process of installing a Victor Jr EFI on my 86 ta. I placed everything on the motor, manifold, 1" spacer, throttle body and 3 inch air filter. I'm happy to report that it fits well and only barely touches the hood insulation. However, I will not be able to use a wingnut to hold the air cleaner. It will require a bolt for better clearance.
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Old 09-29-2009, 07:12 PM   #48
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Re: Single Plane MPFI throttle body question

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FWIW - I'm in the process of installing a Victor Jr EFI on my 86 ta. I placed everything on the motor, manifold, 1" spacer, throttle body and 3 inch air filter. I'm happy to report that it fits well and only barely touches the hood insulation. However, I will not be able to use a wingnut to hold the air cleaner. It will require a bolt for better clearance.
Thanks...with my 2" spacer...I have a little bit less room.
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Old 10-05-2009, 11:55 AM   #49
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Re: Single Plane MPFI throttle body question

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Figured y'all would like to see some pics.





That's beautiful!
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Old 10-07-2009, 02:58 AM   #50
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Re: Single Plane MPFI throttle body question

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What kind of hood do you have? Will this set-up clear a stock hood?
Im running a vic-e, and it does get close to the underside of the hood. I have a carb hat and 3.5" LS1 MAF, and I have only around 1/8" of clearance between the hat/MAF and hood. In order to get that, I had to raise the hood stops to get a little more clearance. With a drop base air cleaner and no spacer, though, it will likely be OK. Most of my clearance issues came up when I swapped out my sagging motor mounts. The stock motor mounts will give you about an extra inch of clearance.
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