I want to increase boost to about 10-11 psi. Right now I'm at 8-9 psi with a 3.25" pulley and V1 blower.

Obviously, I could go with a smaller pulley, but I'm also considering having my ECU sent in to have the rev limit raised. Raising the rev limit to 7000 rpm gives a blower speed almost equivalent to a 3" pulley at 6500 rpm.

Smaller pulley:

pros
1. more boost throughout rpm range
2. cheaper by almost an order of magnitude

cons
1. more labor involved

Raised redline:

pros
1. raised redline enhances mevi performance
2. almost no labor involved
3. can have ECU programmed for 370 cc/min injectors at the same time

cons
1. not cheap
2. boost level up to 6500 rpm stays the same

The added expense of raising the rev limit is an important factor to me right now, but I really like the idea of taking advantage of the mevi.

What would you do?

 

Both!






Honestly, if you can justify the cost of the ECU/injector option, I think it makes more sense. I would think the raised rev-limiter would make the car more fun to drive. Also it would eliminate some of the fuel headaches that you could run into.

 

I'm definitely putting in the larger injectors - they're sitting in my garage right now. Matt has demonstrated that you don't have to go with a reprogrammed ECU to do it, so that saves ~$550.

I don't want to do both right now because any more than about 10-11 psi gets me into the detonation danger zone with substantial additional expense, e.g. J&S, intercooler, etc. I'd rather play it safe for now (if 11 psi can be considered safe).

 

But, if you're considering $300 for the SFMU, I would think the ECU makes more sense. Not only will the ECU control the fuel, but it will simplify the fuel system (no need for a FMU, etc). In addition you get the higher redline and a better "tuned" program.

However, you'd have to get it re-programmed when you change pullies, correct?

 

Very good point. I forgot to consider that. So the ECU route would only be about $250 more expensive. Does that mean that my safc wouldn't be needed? I guess I could sell it.

I don't know, I'm thinking that is true. But that would only be another $100 if that ever happened. Or use the safc to retune.

 

I guess the need for the SAFC would depend on how well JWT programmed the ECU to begin with. Have they actcually done a supercharger program for a car with 370cc injectors?

Well, you'll loose any "boost referenced" fuel management. So, if you went to 13psi or something higher, you'd still be getting the 11psi fuel map, as that's the only thing the car (ECU) knows to do.

But, $100 is reasonable, espescially if they know what they're doing and no dyno-tuning will be necessary.

 

Yes, they have. Basically they take their turbo program, which is based on 370's and apply it (according to what Loren said in a recent thread), maybe with some modifications to account for reduced low end and midrange boost.

 

The JWT ECU SC/Turbo program is essentially the same thing. It is basically ran off the maf voltage so it is boost referenced. As long as your not seeing more than the maf can handle the program will handle fuel/timing with no problem. The sampling per second that the ecu recieves from the maf and other sensors makes specific tuning for different pulley sizes unnecessary. Basically if you are around 350bhp or less then the 370cc and the stock maf will do fine. If your looking for significantly more hp then a maf upgrade would be needed.

What the guys running the JWT ecu will notice is that the torque will be lower due to the ecu pulling timing based on boost and it will be apparent. I know a guy here that ran Jay25 and the JWT setup had a good bit of lag due to the lower torque but as they say better safe then sorry. Stock timing of 15 btdc is conservative enough for boost levels less than ~12 psi as long as you keep it rich ie 12.5 or lower. I thing with a sc less than 12psi the safc and fmu is the way but if a turbo was what you were wanting then I would say get the JWT. Again back to the 7000 rev limit theres no arguing that would go great with a mevi. I would rather change injectors and ecu than a pullie.

 

I agree with the thoughts here about getting the ECU. From what I've personally seen Jim is good about setting up the ECU to your injectors, mods, etc. If you are going to exceedithe Maxima MAF just get a 300ZX MAF, splice it into your harness, and have the ECU programmed for a 300ZX MAF and the 370cc (or whatever) injectors. The SAFC may still be useful for fine tuning since the ECU probably won't be perfect.
-hype

 

350 hp at the crank is only about 300 fwhp, which I expect to exceed, maybe not by a lot, but at least by 20 hp. So maybe instead of upgrading the maf I could just bump up the fuel pressure a bit with a rising rate fpr. But if I'm going to do that, why bother with the ECU upgrade?


Do you know what boost pressure he was running?


Torque will be lower with the SC program? No thanks.

Based on what you're saying, what I would really like is for JWT to just raise the rev limit and make no other changes. I'll handle the fuel delivery with fmu and safc. I asked them about this (just raising rev limit, that is) via email and they haven't responded yet.

 

Stephen, if you could get just the raised rev limit for a reasonable amt ~$200 it would be cool. Jim/Clark and the boys are into making specific changes for small amounts they want the whole $595. With 11psi I would just do the 8:1 disc, 1 step colder, no cat, full exhaust, mevi opening at 5300, 3.12 pulley, 255lph walbro, safc I cant remember my settings, cai for the sc and you will be easily 320fwhp I know I was. I never saw egt exceed 800 and my a/f was a flat 12.5 so you will be happy and not need a j&s.

 

That sounds like the setup I'm after. Thanks, Dave, for the good information.

 

Just got off the phone with JWT. They want $595 just to raise the rev limit, no other changes.

 

I could have told you that. Do the stock ecu with the other necessary stuff and you will make more power than the jwt ecu with the exact same mods.