'00 Coldside E85 Results

[Bill @ Fast Forward]

Well, I am quite pleased with our results in testing my '00 Miata which is now running E85. The conversion entails replacing the stock injectors with 420cc injectors from the RX8. I picked up a used set for around $150 on Ebay and then took them to AZ TPI to get them flow checked. These are the correct sized injectors as they are slightly large for the 50% increase in fuel needed for E85 (stoich AFR of 9.8:1 vs. 14.7:1 for gasoline), however the stock ECU had no problem with the fuel trim, which was -16% and no check engine light. Secondly though, this size injector is necessary to ensure we have enough fuel from the main injectors under full boost with the 125mm or 130mm pulleys (bigger pulleys is the whole point of E85 :)). The theoretical correct size of 370cc would be too small. Also, based on my testing, I think the EGTs for the 125mm pulley look better and with a freeflowing exhaust it would make nearly the same output as the 130mm pulley.

Here is a summary of the parts and settings used for the E85 Coldside:

Pulley Ratio: 125/65
Fuel Injectors: 420cc
Extra Injectors: 750cc/310cc Combo
Main PC Pro File: Main_9900_Ver004
Main PC Pro Settings: 2.5-5-6 (GB-YB-RB)
ECool File: EC_Ver002
ECool Settings: 3 (GB)
Timing Card File: TC_Ver002
Tming Card Settings: 0 (GB)
Max Boost: 14.5-15.5psi (higher number with stock exhaust)

Pulley Ratio: 130/65
Fuel Injectors: 420cc
Extra Injectors: 750cc/310cc Combo
Main PC Pro File: Main_9900_Ver004
Main PC Pro Settings: 2.5-5-6 (GB-YB-RB)
ECool File: EC_Ver002
ECool Settings: 3 (GB)
Timing Card File: TC_Ver002
Tming Card Settings: 0 (GB)
Max Boost: 16-17psi (higher number with stock exhaust)

Attached are the dyno results for the 125mm pulley and the 130mm pulley. The blue line is with an open header, which is to test for the max possible output with a highflow exhaust, and the red line is with a stock midpipe and muffler. Note that the 125mm pulley gained considerably more output with the open header vs. the 130mm pulley. I believe this illustrates the bottleneck we are running into with the 130mm pulley. Thus I recommend that for those of you running E85 to use the 125mm pulley if you are running a non-ported stock head. My engine has a stock unported head with the only modification being 9:1 pistons from a '94-'97.

I have also included the EGTs for the the 125mm pulley and also the 130mm pulley. I think they did very well.

[Steve in VC]

Very nice numbers! And, 0 timing pulled! E85, race gas for the masses.....

The engine dyno'ed, using 100 octane, at Robello's put out 270BHP, which I expect translates to about 240WHP. Do you think Robello's head porting and cam are worth 10HP?

You are running 9:1 pistons. In your opinion, what pulley would be safe with 9.5:1?

Are you looking at a fuel pressure regulator for E85/gasoline on the '00? Would it be the same 25lb/60lb?

Have you managed to stay out of boost enough to see the MPG with E85?

[Bill @ Fast Forward]

Actually, I believe the headwork would be worth closer to 15rwhp based on the Rebello engine results. This is because, on gasoline, I got 225rwhp with the freeflow catless exhaust with the 130mm pulley on my engine. The Rebello engine was running very similar exhaust, with the only real difference being the headwork and intake cam change and made 270hp at the crank, which I estimate would be 240rwhp. On E85, with the same 130mm pulley as before, my car picked up 5rwhp and 10ft-lb compared to its previous gasoline runs.

I am definitely looking into using an adjustable fuel pressure regulator in my car. This would allow me to easily switch between E85 and gasoline and everything in between. At the moment, the only way to do it is to swap the stock injectors and the RX8 420's. Granted I can do it now in under 10 minutes :). Yes, I would expect a similar pressure ratio change as the '90.

I have put enough miles on it that I am getting exactly 2/3 the mpg as with Gasoline. This makes sense because, at stoich, the AFR for E85 is 2/3 that of gasoline... i.e., you need 50% more fuel. I have measured just over 20mpg on the street with E85, though this does include "testing" :). However, I would get a fuzz over 30mpg on the street with gasoline which also included "testing". My car gets particularly good gas mileage because it runs a 3.636 diff with the 5-speed. Revs at only 3200rpm at 75mph. That combined with the stock exhaust makes for a very quiet yet fast ride.

I think with 9.5:1 pistons, the 125mm pulley is the way to go. In fact, I think the 125mm pulley and a freeflow exhaust is the best choice from the results I got even with 9:1 compression. You can run the 130mm pulley, but it will be more on the edge.

[Steve in VC]

Do I smell a non-CARB E85 kit, 225+WHP?

Customer buys RX8 injectors, FFS provides a modified kit

1. 125mm pulley (in place of the 105mm), larger belt
2. A timing card (just in case)

Any plans for an upgrade kit for the single injector kit?

[Rdrcr]

my car picked up 5rwhp and 10ft-lb compared to its previous gasoline runs.

Overall, impressive results with a simple injector and fuel swap but, I was expecting more with E85...what am I missing?

It's nice to know that the PC-Pro can handle these modifications!

Mike

[Rdrcr]

Any plans for an upgrade kit for the single injector kit?

I'll take one please! :)

Mike