EA81 with SPFI question

[[HTi]Johnson]

How much of a difference in horsepower is the EA81 with the SPFI mod than an EA82 spfi?

[mikeshoup]

Consider this:

EA81 Carb has 73 horsepower.

EA82 Carb has 84 horsepower.

EA82 SPFI has 90 horsepower, but also has different cams from the carb version.

 

The EA81 with SPFI will have lower horsepower than an EA82 SPFI. How much, well that's not easy to guess at.

[ScottG]

I checked the specifications under "80s", & found an 84 GL Wagon (EA81), has 73 HP@4800RPM, normally aspirated and 95 HP@4800RPM with FI and a turbocharger. Don't know if that FI is SPFI or multiport. Didn't see any specs on EA81 with FI only & no turbo.

 

Go through the Specifications section carefully to see if there might be some more examples. My quick check saw none.

 

ScottG

[hatchsub]

EA81T was a multiport model not a SPFI. If i had to guess for you id say you would gain a few horses over stock but nothing more than if you threw a weber on it. The main advantage of FI is no cold running problems like a carb. I love my weber dont get me wrong but FI is so much better. Gas milage will be about the same as a weber but maybe a bit better by like a mpg or so.

[SuperNova]

Im running a CCR EA81 with SPFI pistons and .030'' decked off the heads. I did an SPFI swap as well as GM alt swap, open element air cleaner, MSD ignition coil.... And on average i get about 28 mpg. It would probably be in the 30mpg range if i kept my foot out of it. I might be able to get a few more mpg out of it if i got a D/R 5 speed, but the d/r 4 speed as served me well on and off road. Ive asked before about what the estimated HP is but could never get a straight forward answer. Im guessing im pushing around 100hp range. The only way for a positive answer would be to get it to a dyno, but i dont think im gonna waste cash on that. All i know is that the butt-dyno tells me that the car has a whole lot more power over stock.

[GeneralDisorder]

The thing about the SPFI is that it's got specific fuel maps that it adheres to. It will not, under normal circumstances, run rich or lean. It differs from the Weber in that respect as changing the fueling is easy on the Weber, and basically impossible on the SPFI.

 

Now that you understand that, what you have to grasp is that the SPFI is going to correctly fuel for the DEMAND of the engine. That's what it's sensors tell it - demand for air-flow, coolant temp, throttle posistion, and mixture control (O2 sensor). The Weber fuels based on what YOU want the engine to have, not what the engine tells the computer it needs.

 

So you can drive a Weber at a higher fueling rate - gaining performance but decreaseing mileage. The SPFI cannot do that without swapping the ECU for something like MegaSquirt.

 

But the SPFI has other benefits:

 

1. It's designed to flow for a 90 HP engine - so there's room for improvement. 16 HP over stock for the EA81.

 

2. It's capable of better mileage than ANY carb. Although this depends on many factors.

 

3. It runs at any angle allowed by the fuel pickup in the tank. No cornering problems at high speed, and no off-angle power loss when off-roading.

 

4. Cold starting is always perfect.

 

5. It adjusts itself to the demands of the engine. If you install a different cam, it's now the cam that tells the fuel system how it wants to perform. There is nothing to "retune" as there would be in a carb. If more demand is present (IE: more air is flowing) then more fuel will be added by the ECU. It's that simple.

 

6. It can still be retuned for even higher loads by using MegaSquirt and by modifying the fuel pressure, etc. Just like other injection systems. It's up to you though to learn how to do this. It's definately more expensive than tuneing a carb, but also more accurate, and (IMO) more fun. What's not fun about a laptop in the passenger seat?

 

So the question you are asking is very hard to answer. Will the performance improve? To some extent it will. But the performance is more accurately described as "different" rather than "more" or "better". The driveability is much better, but it doesn't have the "snap" of the Weber's progressive linkage, nor does it have the sound of the Weber's air filter. It's comparable, but if you are looking for something that is going to be radically different from the performance of a Weber then you are looking in the wrong place. The performance overall I would characterize as "less torquey on the low end, similar on the high end, and better driveability overall".

 

An SPFI swap has more potential than the Weber, but it quickly becomes more expensive and more time consuming as well. Still I would take it any day over the Weber for both street and off-road. It's quite often I've found that when you NEED the power off-road the Weber is having difficulty with either the angle I'm at or gets contaminated and won't idle right from all the dust and debris. This makes the SPFI superior in any situation where the Weber can't keep itself in-tune due to these non-optimal conditions that don't affect the SPFI at all. I would much rather have the same power consistantly than slightly better power inconsistently. But that's just one man's opinion.

 

GD