2025: DI vs PI

[tenkyouken]

So I've been looking at threads and most people just seem to talk so badly about DI because of price.

Ignoring price, is DI truly "worse" than PI? Is DI more reliable than PI?

Just seems to be a lot of differing views, opinions, thoughts, just trying to get some clarification on 2025!

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[AJRMKV]

It depends on oil viscosity.

 

[alfi.mke]

So I've been looking at threads and most people just seem to talk so badly about DI because of price.

Ignoring price, is DI truly "worse" than PI? Is DI more reliable than PI?

Just seems to be a lot of differing views, opinions, thoughts, just trying to get some clarification on 2025!

not being rude but there’s a whole DI convo thread where a lot of good can be found my friend

 

[tenkyouken]

not being rude but there’s a whole DI convo thread where a lot of good can be found my friend

The thread isn't helpful. Lots of "might as well do PI" or clowning on going DI. Some people have gone DI and have said it's been good. I just want to be well informed on both sides of it.

 

[alfi.mke]

The thread isn't helpful. Lots of "might as well do PI" or clowning on going DI. Some people have gone DI and have said it's been good. I just want to be well informed on both sides of it.

im not an expert by any means but

i mean it seems like you already have an idea.
DI injectors and pump upgrades are more plug and play, simpler setup, but is very pricey and has less power potential.

PI: more power, cheaper, but may be a little more complicated to setup. Also if you’re running bm3 there’s no full integration like with MHD.

not sure what is more reliable, and I don’t know if there is a real answer to that. Personally I’ve had the same thoughts of what to go with. Ultimately decided to go PI for more power

not sure what is more reliable

 

[AJRMKV]

The thread isn't helpful. Lots of "might as well do PI" or clowning on going DI. Some people have gone DI and have said it's been good. I just want to be well informed on both sides of it.

As someone who's done all the basic DI mods I can give you some pointers.

We'll start with the strongest argument against DI first, it is WAY more expensive per HP than DI and it has a lower ceiling if you're aiming for 750 whp+ . There is no way around that.

Based on MSRP prices:

DI Cost for 750whp support:

Injectors: $2100
HPFP: $2500
LPFP: $900

Total: $5400 - Limit (theoretically 800+ whp, but not reliably)

Total PI Cost for 800whp+: $2400


Case for DI made by DI tuners: It stays within engine design parameters, fewer points of failure, less complexity.

Case for PI: Cheaper, more power, reliable enough.

If you want in depth answers on the pros and cons and science behind it, reach out to David Shoup he goes into great deal about this on his Instagram live streams regularly

 

[tenkyouken]

im not an expert by any means but

i mean it seems like you already have an idea.
DI injectors and pump upgrades are more plug and play, simpler setup, but is very pricey and has less power potential.

PI: more power, cheaper, but may be a little more complicated to setup. Also if you’re running bm3 there’s no full integration like with MHD.

not sure what is more reliable, and I don’t know if there is a real answer to that. Personally I’ve had the same thoughts of what to go with. Ultimately decided to go PI for more power

not sure what is more reliable

As someone who's done all the basic DI mods I can give you some pointers.

We'll start with the strongest argument against DI first, it is WAY more expensive per HP than DI and it has a lower ceiling if you're aiming for 750 whp+ . There is no way around that.

Based on MSRP prices:

DI Cost for 750whp support:

Injectors: $2100
HPFP: $2500
LPFP: $900

Total: $4500 - Limit (theoretically 800+ whp, but not reliably)

Total PI Cost for 800whp+: $2400


Case for DI made by DI tuners: It stays within engine design parameters, fewer points of failure, less complexity.

Case for PI: Cheaper, more power, reliable enough.

If you want in depth answers on the pros and cons and science behind it, reach out to David Shoup he goes into great deal about this on his Instagram live streams regularly

Great info. Appreciate the explanations guys.

So how is PI cheaper? If you do go PI, even with the plate, I am under the impression you are still going to want to upgrade the fuel pumps.

what additional things are needed for DI?

 

[AJRMKV]

Great info. Appreciate the explanation!

So how is PI cheaper? If you do go PI, even with the plate, I am under the impression you are still going to want to upgrade the fuel pumps.

what additional things are needed for DI?

You only need to upgrade the LPFP. So let’s say $3300 total. But you’re not limited to 750-800 whp.

In any case, my opinion is that if you want to get the car to that level, it’s a very expensive game to do it right and the price comparison of PI vs DI becomes a much smaller issue.

Shoup, Marin, Sameh have all said that PI should be done properly with an intake manifold. For example Remnant sells a single pass manifold with integrated PI that seems to be a good design. EOS and CSF are some of the expensive options.

You should set and objective and plan around it.

 

[razorlab]

I agree pretty much with @AJRMKV, although his DI prices listed are a bit inflated, and his PI prices are a bit understated.

However, you really need to figure out what your goals are because that is another vector in the decision making here.

Don't want to plunk down $6,000+ to build your transmission? DI would probably be the best route. You can get right up to maxing out the transmission with upgrading just the HPFP and Injectors and that costs right around $3300.

To really utilize PI for 700+ you need to build the transmission.

It's a slippery slope.

 

[tenkyouken]

However, you really need to figure out what your goals are because that is another vector in the decision making here.

Don't want to plunk down $6,000+ to build your transmission? DI would probably be the best route. You can get right up to maxing out the transmission with upgrading just the HPFP and Injectors and that costs right around $3300.

To really utilize PI for 700+ you need to build the transmission.

It's a slippery slope.

Shoup, Marin, Sameh have all said that PI should be done properly with an intake manifold. For example Remnant sells a single pass manifold with integrated PI that seems to be a good design. EOS and CSF are some of the expensive options.

You should set and objective and plan around it.

Yeah, I am trying to set and plan, which is why I'm trying to learn and understand, objectively speaking.

More hp isn't my primary goal and I honestly think of hp as a secondary benefit. I am on flex fuel because CA 91 is ass. I hate mixing, so I want the build to be able to run e85 without sacrificing boost. I also want to take the path that is most reliable (even if it does cost more).

From me looking through the threads to reach my goal with PI, I need to upgrade fuel pumps, intake manifold, motiv+, and turbo.

Am I incorrect?

Is there a way to go down do full e85 path with DI? Am I chasing a pipe dream?

Keeping engine parameters seem more reliable to me. But I'm no expert if that's actually the case.

I don't plan to build the trans, but I am not trying to push it past that point.

 

[AJRMKV]

Yeah, I am trying to set and plan, which is why I'm trying to learn and understand, objectively speaking.

More hp isn't my primary goal and I honestly think of hp as a secondary benefit. I am on flex fuel because CA 91 is ass. I hate mixing, so I want the build to be able to run e85 without sacrificing boost. I also want to take the path that is most reliable (even if it does cost more).

From me looking through the threads to reach my goal with PI, I need to upgrade fuel pumps, intake manifold, motiv+, and turbo.

Am I incorrect?

Is there a way to go down do full e85 path with DI? Am I chasing a pipe dream?

Keeping engine parameters seem more reliable to me. But I'm no expert if that's actually the case.

I don't plan to build the trans, but I am not trying to push it past that point.

If your not planning to build the trans, go with DI. A remnant omega 65 turbo would be ideal for your goals and sounds awesome. You could do S58 injectors and a Fx400X or equivalent HPFP and call it a day.

if you do go that route I’m selling my S58 injectors in April since I upgraded to the nostrum set. I’m upgrading because I have a manual trans that doesn’t have the same limits so I can push the car a lot more with just an upgraded clutch

Shoup would also be the go to guy for DI tuning

 

[tenkyouken]

If your not planning to build the trans, go with DI. A remnant omega 65 turbo would be ideal for your goals and sounds awesome. You could do S58 injectors and a Fx400X or equivalent HPFP and call it a day.

if you do go that route I’m selling my S58 injectors in April since I upgraded to the nostrum set. I’m upgrading because I have a manual trans that doesn’t have the same limits so I can push the car a lot more with just an upgraded clutch

Shoup would also be the go to guy for DI tuning

Is there a reason to go remnant omega versus something like a pure 800 or a CTS?

 

[AJRMKV]

Is there a reason to go remnant omega versus something like a pure 800?

Lots of reasons:

1. It’s a stock location full frame dual ceramic ball bearing turbo. Whereas the pure 800 is a journal bearing hybrid
2. It comes with the charge pipe and intake.
3. Service is epic, and the owner is super responsive
4. It has a T51R mod so turbo sounds much louder

5. It has a much higher ceiling than the pure 800 and is capable of low 4s 60-130. ( not that it matters if you don’t build the trans)
6. It’s $3500

I’ve had mine for 6000 hard miles with no issues. However, if budget is important, you can definitely find a cheaper used pure 800.

just saw that you mentioned CTS. If you use that turbo it take different fuel, seemingly USD only and it burns it FAST.

you can read through the forums for more details on that one

 

[tenkyouken]

Lots of reasons:

2. It comes with the charge pipe and intake.

Currently have a charge pipe and intake already ? So idk if that's the route for me.

 

[AJRMKV]

Currently have a charge pipe and intake already ? So idk if that's the route for me.

DAW is also a solid option, specifically the 6769.

You can use standard aftermarket intake and charge pipe with both iirc

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