To MPI or to not MPI

[PowerDemon]

Hello all,

It’s about time for a carbon clean at 85k. I’ve experienced some bumpy cold starts and ever decreasing fuel economy. So I figure while the manifold is off getting the valves cleaned, why not throw on a Euro manifold and install MPI.

Here’s the catch. I don’t plan on running ethanol yet, but I like the idea of having the additional fueling headroom and a backup set of injectors so if one of the DI’s get stuck at WOT it doesn’t toast the whole motor immediately. Can I expect any power gain with MPI on just 93 pump gas? If so how much? I plan to eventually run full E85 but I’m going to need a PM4 as well and that’s not in the cards right now. Normally I would wait and do it all at once, but I want to get this carbon cleaning done and kill two birds with one stone. Is it worth it? What do you guys think?

 

[jimlloyd40]

It's worth it just to eliminate future carbon cleaning but I don't think it would add any power without also adding ethanol.

 

[JerseyDrew77]

You'll only get the cleaning affect but no additional power using 93.

 

[jay745]

You'll only get the cleaning affect but no additional power using 93.

Well that's just not true. There's a significant power increase using meth on a 93 tune. Absolutely worth it

 

[jimlloyd40]

Well that's just not true. There's a significant power increase using meth on a 93 tune. Absolutely worth it

He didn't ask about meth. But good point.

 

[jay745]

He didn't ask about meth. But good point.

Not enough coffee! I read mpi as wmi

Carry on

 

[JerseyDrew77]

Well that's just not true. There's a significant power increase using meth on a 93 tune. Absolutely worth it

Bro, I think you're on Meth right now. He wasn't asking about meth.

 

[jay745]

Bro, I think you're on Meth right now. He wasn't asking about meth.

I am

 

[El_bigote_AJ]

Better question is are you still only at 28psi? And how much head room do you have in your current fueling to go up to 32/33 psi?

 

[PowerDemon]

Better question is are you still only at 28psi? And how much head room do you have in your current fueling to go up to 32/33 psi?

Actually the tune is only running 27psi right now. We had to turn it down for the Massachusetts winter gas. I haven’t bothered to turn it back up since I’ve been home in Virginia with much better fuel. We have had the car up to 31psi before on (Virginia) 93 but had to back off once I went back to Mass for the winter. Supposedly we were at the knock threshold for 93. So I guess additional fuel wouldn’t help…?

 

[El_bigote_AJ]

In that case, depending on how far down the line you plan to go ethanol…. I would suggest water/meth, then you can stick with 93 - have the ability to have nick turn up the timing a significant amount and it will cost less than a euro manifold and aftermarket fuel rail and injectors. Also you’ll get the cleaning benefits.

I just looked at the log from when you ran some mid 9 sec 60-130 and at that psi that turbos actual gate was below 60s - that V1s got lots more potential in it.

 

[Mk7Matt]

I'm doing the same thing. I'm at almost 100k miles and thought it would be a good time to go MPI since I'll have the manifold off and clean valves to start with...

 

[Subliminal]

Just to make sure I understand it correctly: MPI is basically the same as what Toyota uses in their DI engines, correct?

 

[PowerDemon]

In that case, depending on how far down the line you plan to go ethanol…. I would suggest water/meth, then you can stick with 93 - have the ability to have nick turn up the timing a significant amount and it will cost less than a euro manifold and aftermarket fuel rail and injectors. Also you’ll get the cleaning benefits.

I just looked at the log from when you ran some mid 9 sec 60-130 and at that psi that turbos actual gate was below 60s - that V1s got lots more potential in it.

I’d like to run E40 with no PM4 or E85 with the PM4. I just need to try blending ethanol myself to see if it’s gonna be as bad as I think. It’s really the hassle of blending that is keeping me away from this whole thing lol
Yeah it does. I’ve been pretty pleased with the turbo so far.

I would rather stay away from water meth for now. I don’t like the idea of the well being of my motor relying on a glorified windshield washer pump.

Yeah it does. I’ve been pretty pleased with the turbo so far.

 

[El_bigote_AJ]

Just to make sure I understand it correctly: MPI is basically the same as what Toyota uses in their DI engines, correct?

maybe... without googling it - if they add extra injectors before the intake valves then the basic mechanics of it are the same. for also does it for their DI motors too.