More on Edelbrock 3500 EFI
Discussion
OK guys,
I have fought with this system since the day I put it in car. I just want anyone contempating this system to be aware of the issues and the solution I had to go to...
Firstly, the system was installed and "pre-tuned" by the engine builder. Great guys, and know race engines. This is on no way reflective of thier work, as they have gone above and beyond to make things right.
On the engine dyno, the system worked well, but in real application, the system was less than perfect. I took it to a EFI tuner with a chassis dyno that the engine builder recomended and had worked with before. The tuner spent a LOT of time on the car, and after a new set of bigger injectors, a new chip, a upgraded ignition system and too much time on the chassis dyno (read $$$) it still would not pass emissions (a rather lax idle test at that). There were also drivability issues on the low end. It was jerky and loped quite a bit. Switching gears helped, but it was not the way I wanted the car to be.
To make a long and rather frustrating and expensive story short, the engine came back out of the car and taken to the engine builder for evaluation. We were looking to see if there was a problem with the cam or valvetrain or something else? In the end, the EFI system was the culprit.
Solution? Pull the damn thing out, and replace with a new intake manifold and carb. The engine builder is making it right by buying and installing a Vortech supercharger, along with the new Demon carb. I had the engine built with a supercharger in mind (forged pistons, appropriate compressions etc.)
The factory recommended not installing the 3500 system, but I had already purchased it. Evidently they had problems (or heard of the problems) before.
I know there are other systems out there. I can't speak for Accel, Holley and the other "affordable" systems, but I can SAFELY say the Edelbrock system is NOT the best option. For the additional money I sunk into this, I could have purchased a Kinsler EFI. Sad but true.
Anybody want to buy a gently used Edelbrock 3500 EFI system? :rolleyes:
Allen
I have fought with this system since the day I put it in car. I just want anyone contempating this system to be aware of the issues and the solution I had to go to...
Firstly, the system was installed and "pre-tuned" by the engine builder. Great guys, and know race engines. This is on no way reflective of thier work, as they have gone above and beyond to make things right.
On the engine dyno, the system worked well, but in real application, the system was less than perfect. I took it to a EFI tuner with a chassis dyno that the engine builder recomended and had worked with before. The tuner spent a LOT of time on the car, and after a new set of bigger injectors, a new chip, a upgraded ignition system and too much time on the chassis dyno (read $$$) it still would not pass emissions (a rather lax idle test at that). There were also drivability issues on the low end. It was jerky and loped quite a bit. Switching gears helped, but it was not the way I wanted the car to be.
To make a long and rather frustrating and expensive story short, the engine came back out of the car and taken to the engine builder for evaluation. We were looking to see if there was a problem with the cam or valvetrain or something else? In the end, the EFI system was the culprit.
Solution? Pull the damn thing out, and replace with a new intake manifold and carb. The engine builder is making it right by buying and installing a Vortech supercharger, along with the new Demon carb. I had the engine built with a supercharger in mind (forged pistons, appropriate compressions etc.)
The factory recommended not installing the 3500 system, but I had already purchased it. Evidently they had problems (or heard of the problems) before.
I know there are other systems out there. I can't speak for Accel, Holley and the other "affordable" systems, but I can SAFELY say the Edelbrock system is NOT the best option. For the additional money I sunk into this, I could have purchased a Kinsler EFI. Sad but true.
Anybody want to buy a gently used Edelbrock 3500 EFI system? :rolleyes:
Allen
Just looking on their site www.edelbrock.com/automotive/mpfi_sbchevy.html
says "comes with 27lb injectors for up to 450bhp"
I was running 26lb on my 350, with a very moderate 300bhp (lots of torque though) and quickly got to the limit of them.
>> Edited by eliot on Wednesday 13th July 16:26
says "comes with 27lb injectors for up to 450bhp"
I was running 26lb on my 350, with a very moderate 300bhp (lots of torque though) and quickly got to the limit of them.
>> Edited by eliot on Wednesday 13th July 16:26
when it was on the dyno was the rear of the car on or off the car?
When I did the inital dyno tunning on my canam the rear of the car was off. With the rear on the car wouldn't even idle do to the increased air restriction the rear deck put on the air box. When I go back for additional tunning it's going to be done on the street.
mark
When I did the inital dyno tunning on my canam the rear of the car was off. With the rear on the car wouldn't even idle do to the increased air restriction the rear deck put on the air box. When I go back for additional tunning it's going to be done on the street.
mark
Well, I am not exactly sure how they figure it, but in a real world application, 27 lb. injectors will not support 450 hp (mine is 550+/-). I went to 40 lb injectors with lower fuel pressure. Either way, the system is inadequate for a hi-po engine. (IMHO). It does not handle idle/just off idle well, and with a lightweight car, exacerbates the low-end drivability issues inherent with the system.
Perhaps on a less demanding engine and heavier weight vehicle, it might suffice? Either way, I don't feel like the fuel delivery system and tunability of this sytem is worth the money, the modifications or the headache.
I will admit I am a bit cranky about it. Its beautiful here, the roads are calling, and my engine is in the shop. Thats bad enough, but after spending $2,300 on the system, $400 on new injectors, $1,800 in tune/dyno time, my time pulling the engine back out, having to put it back in when its fixed, and tossing the entire sytem in the end after all that, I am a less than a pleased customer. The bottom line here I guess, is that I am sharing my experience so that others can either budget for a real EFI system and not one made by Playschool, or go with the carb and save the money, downtime and frustration.
Edited to add - It was dyno'd with the rear clip on and off. Airflow wasn't the issue... I had a 6" tall Kool Blue air filter on it. It was not starved for air, and the AFR meter showed the same mix with clip on or off. Mine is a GTR, so possibly the volume of air under the bonnet makes a difference?
Allen
>> Edited by Allen-GTR on Wednesday 13th July 17:02
Perhaps on a less demanding engine and heavier weight vehicle, it might suffice? Either way, I don't feel like the fuel delivery system and tunability of this sytem is worth the money, the modifications or the headache.
I will admit I am a bit cranky about it. Its beautiful here, the roads are calling, and my engine is in the shop. Thats bad enough, but after spending $2,300 on the system, $400 on new injectors, $1,800 in tune/dyno time, my time pulling the engine back out, having to put it back in when its fixed, and tossing the entire sytem in the end after all that, I am a less than a pleased customer. The bottom line here I guess, is that I am sharing my experience so that others can either budget for a real EFI system and not one made by Playschool, or go with the carb and save the money, downtime and frustration.
Edited to add - It was dyno'd with the rear clip on and off. Airflow wasn't the issue... I had a 6" tall Kool Blue air filter on it. It was not starved for air, and the AFR meter showed the same mix with clip on or off. Mine is a GTR, so possibly the volume of air under the bonnet makes a difference?
Allen
>> Edited by Allen-GTR on Wednesday 13th July 17:02
stig said:
Hey guys, out of curiosity, what injector size would you recommend for a 400hp engine?
I'm fitting 36lb/hr injectors to my 456 bhp AS engine (only dynoed at 400 at the crank so far but I think that was timing related and it had a low rev limit). I calculated this using my original dyno sheet's BSFC numbers as well as by the seat of the pants calculator here: www.msefi.com/msinfo/manual/minj.htm
I'd figure that 32 lb/hr would be fine for 400 bhp.
The Edelbrock system doesn't seem very flexible and comes over as pretty crude (replacement chips! - this is 2005). Does it let you adjust the number of squirts per rev or choose between alternating squirts or all-at-once. These settings can make quite a difference to idle smoothness. If you have a lumpy idle then you can fit a fuel filter in the MAP pickup line with a MIG welding tip to provide an accurately controlled restriction ( www.msefi.com/msinfo/manual/mig.gif ). It's sort of like a low-pass filter only for air. There's a lot of good generic tuning advice here: www.msefi.com/msinfo/manual/mtune.htm
Well, Based on my experience and talking to a couple of guys that make their living with this stuff, 400 hp would requre a minimum of 32 lbs. However, you can go slightly bigger and use less fuel pressure.
There is a formula for this, though I do not know what it is. I am basing this on their responses to my questions. (answers were quite consistent).
Allen
There is a formula for this, though I do not know what it is. I am basing this on their responses to my questions. (answers were quite consistent).
Allen
Allen-GTR said:
There is a formula for this
The math is on the msefi. Just err on the larger sizes if between two std sizes. I think the sizing is done for stoich mixtures (14.7), wheras you'll want to run around 12 or less under load.
As others have said, you can always drop the fuel pressure, but it only reduces the effective rating a little bit.
i.e. I made my 26lb injectors look like 29's by raising from 42 psi to 60 psi. I didn't want to raise it any further, as under [my low] boost they would see 65psi which was about as much as i wanted to put through them.
Allen-GTR said:
There is a formula for this, though I do not know what it is.
It's on the site I linked to. As Eliot says you will need to scale from stoich i.e. multiply by 12.9/14.7 assuming a target AFR of 12.9.
I was lucky when running my sizing calcs to have the actual Brake Specific Fuel Consuption(BSFC) values from when the engine was run on the dyno under max load. This means I know pretty accurately just how much my engine is going to need, worst case. Course this needed a carb...
The site I linked to also has a calculator for figuring out just how much flow you'll get for a set of injectors running under or over their rated pressure.
As I mentioned a while back on a previous post, we'll be working with Chris Richards, using my CanAm as a test bed to replace the 3500 which I after over 10,000 miles, and absolutley hate.
Chris says I can keep my intake manifold, and he'll rework the throttlebody. Replace the distributor, computer and harness. Will be cheaper than a whole new system. He's been swamped creating a similar system for the Cobras with Ford engines, but he'd like to get into the SB Chevvys.
As an incentive to Chris, would like to know who would be interested in this new system, and I'll pass it on to him.
Jack
Chris says I can keep my intake manifold, and he'll rework the throttlebody. Replace the distributor, computer and harness. Will be cheaper than a whole new system. He's been swamped creating a similar system for the Cobras with Ford engines, but he'd like to get into the SB Chevvys.
As an incentive to Chris, would like to know who would be interested in this new system, and I'll pass it on to him.
Jack
In my case, I will chalk this one up to bad timing. I would have looked into the upgrade a month ago, but I needed to do something to get my car on the road. Is there anything more torturous than having an Ultima in the garage and NOT be able to drive it during the best weather of the season?!?!? 
Jack, Let me know how that goes... I hope you are able to get it performing correctly. If he wants a test system to work with before handing yours to him, let me know. I have a complete system on the shelf I'd make him a deal on!
I originally went with the EFI system to avoid changing out jets when going from Denver altitude to sea level (and back), but realistically, if I do it twice a year, and it takes 30 minutes, I can afford the time...
I went to talk to my engine builder yesterday afternoon. I should have the engine back in a couple of weeks. He's ordering the supercharger this morning and will have it in a week. He said he'd need a week to install, dyno and tune. Hopefully I will be ready for the Reno trip!
Allen
Jack, Let me know how that goes... I hope you are able to get it performing correctly. If he wants a test system to work with before handing yours to him, let me know. I have a complete system on the shelf I'd make him a deal on!
I originally went with the EFI system to avoid changing out jets when going from Denver altitude to sea level (and back), but realistically, if I do it twice a year, and it takes 30 minutes, I can afford the time...
I went to talk to my engine builder yesterday afternoon. I should have the engine back in a couple of weeks. He's ordering the supercharger this morning and will have it in a week. He said he'd need a week to install, dyno and tune. Hopefully I will be ready for the Reno trip!
Allen
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