XDI High Pressure Fuel Pump upgrade

engineermike

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I had been interested in upgrading the HPFP on my Whipple 2018 GT for some time, but I could find very little information on it or anyone outside of a shop who’s installed one. I recently purchased one from 5 Star Tuning and installed it, so I thought I would put this out there in case anyone else was interested.

First off, the point of gdi is to reduce knock as a result of charge cooling from vaporization of fuel. Port injection mainly cools the metal surfaces but gdi cools the air more. This is what allows the gen3’s 1 number compression increase over gen2. The stock gen3 calibration runs 90% gdi and 10% port at wot and the stock High Pressure Fuel Pump is not far from max capacity. So, when boost is added, while you need MORE knock suppression, the capacity isn’t there and you wind up running only 60-65% gdi. The xdi HPFP45 has 45% more capacity than the stock pump so at 10-11 psi you can get back to the 90% gdi range like stock. Keep in mind that at 60% gdi you are still getting decent benefit from the gdi, just not all of it. Note that the benefits of running gdi over port are even more pronounced on e85 than gasoline, but there also isn’t as much need.

Installation: My kit didn’t come with instructions. I thought there just wasn’t any because the install seemed straight forward enough. I was wrong on both counts. It’s more complicated than it seemed at first. I contacted xdi and they emailed me instructions which are critical. You have to swap the #2 coil-on-plug with #3 coil-near-plug to make room for the pump. This also involves re-pinning the coil connectors and reversing polarity, which isn’t as hard as it sounds. I found it interesting that the #3 coil uses a different plug and polarity than the rest. If I could do it over I believe I would buy an additional coil-near-plug coil/wire and run that on both 2 and 3, which would take a little trimming with an xacto. As it’s installed, I don’t think you can remove the #3 coil without first removing the high pressure fuel line from the pump. ***Edit: see post #9 below***

Tuning: Understand that there are two aspects to the tuning. One is making the pump work, and the other is how you take advantage of it. If you use a tuner, my bet is that someone like Lund will handle both aspects. For mine, prior to the pump install, I had disabled knock advance for reasons that would take much longer to explain. I set it up such that the spark timing ramped up and it had knock retard in the middle of the power range. I could repeatably get 1.2-1.4 deg of knock retard right around 5000 rpm at 65% gdi blend on the stock pump.

Results: I made no other changes to the tune other those required and increasing gdi blend from 65% to 90%. It started and ran perfectly on the first try. I logged several full-throttle pulls and the duty cycle of the new fuel pump never exceeded 80%. I also got zero knock retard on any of the pulls, not even on any individual cylinder, so there is a definite improvement in knock suppression.

The next step will be to start adding spark timing (or boost) to find the new limit.

 
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gixxersixxerman

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Well I’ll be watching this...
 

markmurfie

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Interesting. Are you just purely looking at knock and timing, no before and after dyno numbers, draggy street runs, or other metric to compare before and after? I think IIRC they made right at 1k on pump gas, with this kit, using a built engine and turbo kit.
 

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Interesting. Are you just purely looking at knock and timing, no before and after dyno numbers, draggy street runs, or other metric to compare before and after? I think IIRC they made right at 1k on pump gas, with this kit, using a built engine and turbo kit.
I think what you are getting at is this a mod to improve the health of the power being made or is it to make more power.
 

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If I read the OPs post correctly. The cooling benefit of the fuel being directly injected into the cylinder helps keep detonation at bay. More demand of the fuel system under boost, decreases the amount of DI fuel, due to the limits of the stock pump. Adding a higher volume pump eliminates that and keeps the ignition timing from retarding and thereby making more power. I think that's what the OPs trying to convey.
 


markmurfie

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If I read the OPs post correctly. The cooling benefit of the fuel being directly injected into the cylinder helps keep detonation at bay. More demand of the fuel system under boost, decreases the amount of DI fuel, due to the limits of the stock pump. Adding a higher volume pump eliminates that and keeps the ignition timing from retarding and thereby making more power. I think that's what the OPs trying to convey.
More timing doesnt always mean more power, Is what i'm getting at.

Detonation has different levels of intensity. a 5 hp engine can have audible detonation with little risk of damage. a 500hp engine detonation has enough energy before its detectable by the human ear to cause major damage. At 800hp, even relying on a very sensitive knock sensor, its very dangerous.
 
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engineermike

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I thought it was understood and accepted that forced-induction stock-compression gen3 coyotes on pump gas were all running well below MBT and, therefore, increases in spark timing advance would yield torque and power gains. This can be verified by many, including Dustin Whipple and 3rd party calibrators.
 
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engineermike

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UPDATE: I wasn’t super-happy with the fitment of the #3 coil-on-plug because it appeared you had to remove the high pressure fuel line from the pump to remove the coil. However, I tried and you can actually snake the coil out of there without removing the line or pump. The same is true for #2. Also, the connector you would need to install two coil-near-plugs *the right way* doesn’t appear to be readily available. The connectors for all the coil-on-plugs is WPT-1502 but the coil-near-plug connector is different. You *could* use an XActo to trim the coil-side of the connectors to fit either but I wouldn’t on my car.
 

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I think MBT timing on high compression engines with forced induction is a lot lower than people think. MP25 near peak torque RPM. How do you know if you are not measuring the torque output of the engine in any way?

HC MBT.PNG
 

Slopoke

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Quick question, if I were to install a higher volume HPFP, can the Whipple tune support it? Or, should I say, will there be any upside? Not looking for massive HP, just want to get the benefit of not having the DI percentage go down and keep the evil detonation gremlins at bay.

Also, if a higher volume HPFP will benefit me, could I use a lower volume pump than you have? I've come across a -25 for $1599.00. That price I can do, I can't fork out $2500.00 for the -45 pump.
 
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engineermike

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@Slopoke the Whipple tune as supplied will not support this upgrade. The cal has to be changed to a) run the pump properly and b) take advantage of it. You have 2 options: 1) get HPTuners, work with XDI to get the pump to work, and make your own changes to take advantage of it (pretty easy and I can help), or 2) pay someone like Lund or 5 Star to make all the changes for you. As for the size, you are right that the price is high and the difference is significant. The smaller one is only 22% over stock, as opposed to 47%. First, understand that I set mine up such that there's enough overhead in the pump size to handle 0.71 lambda (cat protect) and 20 deg ambient temp. Based on that, on a typical WOT pull, I might only see 80% duty cycle and consider that a good limit because I know it can handle more extreme conditions. Many people in the EB world push the GDI fueling until they see 100% duty cycle and the rail pressure starts falling off. That said, if you are running 65% GDI now, which is generally safe with overhead on a 10-11 psi Coyote, then 65 x 1.22 = 80%. I personally wouldn't be happy spending $1600 and still not being able to run 90% blend like stock. My guess is you could command 90% and it would handle it most of the time, just without overhead. I am told that the PCM will either automatically supplement with port or cut throttle when this happens, depending on how the cal is set up, but I haven't verified this myself.

@markmurfie I had long technical response written up, but decided to try a different approach. I'm not trying to convince you or anyone to buy this product, nor trying to prove I gained power. Myself and most, if not all, others running a boosted pump-gas stock-compression gen3 Coyote are convinced, for many reasons, that we are well below MBT when encountering knock. As a result, I am certain that I gained power and will be pushing the spark higher to see if more is there. If you don't believe me, that's fine. I've shared what I know and posted significantly more information on the matter than what was previously available, so I think I've achieved my goal of helping anyone who is in my prior position.

Disclaimer: If you believe you are already running at or near MBT spark timing without knock, then this modification probably isn’t for you. If you require before/after dyno results to be convinced that I gained power, then disregard this entire thread.
 

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I had been interested in upgrading the HPFP on my Whipple 2018 GT for some time, but I could find very little information on it or anyone outside of a shop who’s installed one. I recently purchased one from 5 Star Tuning and installed it, so I thought I would put this out there in case anyone else was interested.

First off, the point of gdi is to reduce knock as a result of charge cooling from vaporization of fuel. Port injection mainly cools the metal surfaces but gdi cools the air more. This is what allows the gen3’s 1 number compression increase over gen2. The stock gen3 calibration runs 90% gdi and 10% port at wot and the stock High Pressure Fuel Pump is not far from max capacity. So, when boost is added, while you need MORE knock suppression, the capacity isn’t there and you wind up running only 60-65% gdi. The xdi HPFP45 has 45% more capacity than the stock pump so at 10-11 psi you can get back to the 90% gdi range like stock. Keep in mind that at 60% gdi you are still getting decent benefit from the gdi, just not all of it. Note that the benefits of running gdi over port are even more pronounced on e85 than gasoline, but there also isn’t as much need.

Installation: My kit didn’t come with instructions. I thought there just wasn’t any because the install seemed straight forward enough. I was wrong on both counts. It’s more complicated than it seemed at first. I contacted xdi and they emailed me instructions which are critical. You have to swap the #2 coil-on-plug with #3 coil-near-plug to make room for the pump. This also involves re-pinning the coil connectors and reversing polarity, which isn’t as hard as it sounds. I found it interesting that the #3 coil uses a different plug and polarity than the rest. If I could do it over I believe I would buy an additional coil-near-plug coil/wire and run that on both 2 and 3, which would take a little trimming with an xacto. As it’s installed, I don’t think you can remove the #3 coil without first removing the high pressure fuel line from the pump. ***Edit: see post #9 below***

Tuning: Understand that there are two aspects to the tuning. One is making the pump work, and the other is how you take advantage of it. If you use a tuner, my bet is that someone like Lund will handle both aspects. For mine, prior to the pump install, I had disabled knock advance for reasons that would take much longer to explain. I set it up such that the spark timing ramped up and it had knock retard in the middle of the power range. I could repeatably get 1.2-1.4 deg of knock retard right around 5000 rpm at 65% gdi blend on the stock pump.

Results: I made no other changes to the tune other those required and increasing gdi blend from 65% to 90%. It started and ran perfectly on the first try. I logged several full-throttle pulls and the duty cycle of the new fuel pump never exceeded 80%. I also got zero knock retard on any of the pulls, not even on any individual cylinder, so there is a definite improvement in knock suppression.

The next step will be to start adding spark timing (or boost) to find the new limit.
Did you do the camshaft with the larger lobe as well? I thought that was part of the complete “kit” or are you seeing these results with just the pump being swapped out? DI has great potential for power increases.
 
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engineermike

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Did you do the camshaft with the larger lobe as well? I thought that was part of the complete “kit” or are you seeing these results with just the pump being swapped out? DI has great potential for power increases.
I did not do the camshaft or the injector upgrade. As of now, I am not limited By the GDI system.
 

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Big DI injectors and Pumps = Big power gains.

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Discussion

They just hurt the wallet. (Ive made 1,216 rwhp on DI only... its awesome)
 

 
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